Near-field visual acuity of pigeons: effects of head location and stimulus luminance.

Two pigeons were trained to discriminate a grating stimulus from a blank stimulus of equivalent luminance in a three-key chamber. The stimuli and blanks were presented behind a transparent center key. The procedure was a conditional discrimination in which pecks on the left key were reinforced if the blank had been present behind the center key and pecks on the right key were reinforced if the grating had been present behind the center key. The spatial frequency of the stimuli was varied in each session from four to 29.5 lines per millimeter in accordance with a variation of the method of constant stimuli. The number of lines per millimeter that the subjects could discriminate at threshold was determined from psychometric functions. Data were collected at five values of stimulus luminance ranging from--0.07 to 3.29 log cd/m2. The distance from the stimulus to the anterior nodal point of the eye, which was determined from measurements taken from high-speed motion-picture photographs of three additional pigeons and published intraocular measurements, was 62.0 mm. This distance and the grating detection thresholds were used to calculate the visual acuity of the birds at each level of luminance. Acuity improved with increasing luminance to a peak value of 0.52, which corresponds to a visual angle of 1.92 min, at a luminance of 2.33 log cd/m2. Further increase in luminance produced a small decline in acuity.


Detection of the velocity of movement of visual stimuli by pigeons?

Nine pigeons were trained to discriminate a moving stimulus from a stationary stimulus. In one experiment, the stimulus was a rotating disc with radial stripes. In a second experiment, the stimulus was a vertically moving film strip with horizontal bars. Several psychophysical procedures were used to determine the minimal detectable velocity of movement. The detection thresholds for most of the pigeons fell in the range of 4.4 to 6.5 millimeters per second, corresponding to a retinal velocity of 4.1 to 6.01 degrees per second. A signal detection analysis of the psychophysical data indicated systematic changes in response bias that were related to the ordinal position of the stimulus velocity in the sequence.


Control by the auditory or the visual element of a compound discriminative stimulus: effects of feedback.

Groups of pigeons were trained to depress a treadle in the presence of a compound stimulus consisting of a tone and a red houselight (a) to avoid electric shock, or (b) to obtain grain. Immediate, exteroceptive feedback was equated for avoidance and appetitive groups within an experiment, but varied across experiments from elevation of a nonilluminated feeder to darkening of the chamber, termination of the tone, and elevation of an illuminated feeder. Responding in the absence of the compound stimulus postponed its next occurrence. After performance had stabilized, the degree to which each element controlled treadle pressing was determined. Generally, in the appetitive tests, the red light controlled much more responding than did the tone, but in the avoidance tests, the tone controlled more responding than did the red light.


Excretion of alkaloids by malpighian tubules of insects.

Nicotine is transported at high rates by Malpighian tubules of larvae of Manduca sexta, Pieris brassicae and Rhodnius prolixus and the transport persists in the absence of alkaloid from the diet. In the fluid-secreting portion of Rhodnius tubules this transport is not coupled to ion transport, nor is it dependent on the physiological state of the animal. The transport, which can occur against a steep electrochemical gradient, shows saturation kinetics with a maximal rate of 700 pmol. min-1 per tubule and is half saturated at 2-3 mM. Nicotine transport independent of ion movements also occurs in the lower resorptive parts of Rhodnius tubules. Both portions of Rhodnius tubules can transport morphine and atropine. These alkaloids and nicotine compete with one naother and are presumed to be carried by the smae transport system. Nicotine transport in Rhodnius was unaffected by organic anions, such as amaranth and benzyl penicillin, or by the organic anion transport inhibitor, probenecid. Fluid secretion in 5-HT-stimulated tubules was reduced by atropine and nicotine, probably by blocking the 5-HT receptors. The Malpighian tubules of adult Calliphora erythrocephala and Musca domestica remove nicotine from bathing solutions, an unknown metabolic accumulating in the tubules. Adult P. brassicae and M. sexta do not exhibit transport of nicotine by their Malpighian tubules.


Ciliary propulsion of objects in tubes: wall drag on swimming Tetrahymena (Ciliata) in the presence of mucin and other long-chain polymers.

The lubrication effect of three long-chain polymers - mucin, methylcellulose and Ficoll - on ciliary propulsion in tubes is measured by plotting the relative velocities of swimming cilitates as a function of the tube bore diameter. Mucin shows the most unequivocal lubrication, which is found at concentrations between 0% and 9.1% (w/v). This observation, coupled with viscometric measurements which show that ciliary tip shear rates are sufficient to solate mucin, serve as  the groundwork for a model of mucin lubrication which explains the optimized lubrication behaviour of thixotropic gelating polymers as an expression of the response to shear by the various stages of polymer clustering during the gelatin process. In addition to the lubricative effect, another wall drag reduction effect by mucin was measured in the clearance region beyond the lubrication layer. This apparent viscosity reduction is optimized in the concentration range between I.7% and 4.I% mucin and may also be explained in terms of the properties of gel clustering.


Horomonal control of larval diapause and metamorphosis of the southwestern corn borer Diatraea grandiosella.

Changes in haemolymph juvenile hormone (JH) concentrations of larvae of the southwestern corn borer, Diatraea grandiosella, were used to estimate the activity of the corpora allata. The haemolymph of penultimate nondiapause instars contained a maximum JH titre of 3000 Galleria units (GU)/ml, whereas the titre in the final instar had dropped to 140 GU/ml within 6 h of the ecdysis and continued to remain low. Corpora allata of last-stage non-diapause larvae therefore remain inactive. Some signal other than a rapidly declining JH titre in mid-instar triggers the release of ecdysiotropin because the pupal moulting cyclic did not become independent of the brain and ecdvsial glands until 4-25 and 4-75 days after the final larval ecdysis, respectively. Newly diapaused immaculate larvae had a haemolymph JH titre of ca. 1500 GU/ml. Three JH mimics applied to early last stage non-dispause larvae induced the formation of the immaculate dispause morph. The mimics did not activate the recipient's corpora allata, but elevated the function JH concentration, each having a different intrinsic hormonal activity. Threshold JH concentrations which control larval ecdyses, dispause maintenance, and metamorphosis are presented.


Studies on the mechanism of fluid secretion by isolated salivary glands of Calliphora.

1. Potassium is the major cation in the secretion of the salivary glands of Calliphora and is necessary for full secretory rates. 2. Other ions (rubidium and sodium) can support secretion in the absence of potassium. 39. During stimulation with 5-HT a Nernst plot of the basal membrane potential has a slope of 53 mV for a tenfold change in external potassium concentration and the slope at rest deviates from this over the range I-20 mM external potassium. 4. Hyperpolarization of the basal membrane by 5-HT is abolished if the chloride in the bathing medium is replaced by isethionate. 5. The diuretic agent amiloride inhibits fluid secretion by a mechanism which may include a reduction in calcium entry in addition to its recognized effect on sodium permeability. 6. A model is proposed in which fluid secretion is driven by the active transport of potassium across the apical membrane with chloride following passively.


Neural regulation of the heart muscle in an isopod crustacean: acceleration and peripheral inhibition.

1. In the neurogenic heart of the isopod crustacean Porcellio dilatatus, repetitive electrical stimulation of the cardiac nerves elicted either cardio-acceleratory or cardio-inhibitory effects depending on the stimulation parameters. 2. Acceleratory effects were accompanied by a decrease of membrane potential and by changes in the contour of the spontaneous electrical responses: increase in the speed of the rising phase and enhancement of the plateau phase. 3. Inhibitory stimulation acted on rhytjmicity and/or contour of spontaneous responses. At stimulation pulse frequencies beyond 25/s a hyperpolarization appeared after the cessation of the inhibitory train. 4. Inhibitory stimulation elicted IJPs in the myocardium. Their reversal potential was found to be close to the value of the resting membrane potential. During inhibitory stimulation, the membrane resistance of the heart muscle was frequently decreased. 5. The effects of changing the external chloride content, and of adding GABA and picrotoxin support the hypothesis that the inhibitory impulses increased the myocardium permeability to CL-. 6. On the basis of these findings it is assumed that cardio-inhibitory fibres act on both cardiac ganglion and myocardium. 7. Comparisons are established between the wood-louse's heart and the skeletal or heart muscle of some arthropods. The functional significance of peripheral inhibition is further discussed in relation to the nature of the spontaneous electrical responses and to contraction.


The unreliability of mammalian glomerular markers in teleostean renal studies.

1. The assumption that (3H) methoxy inulin, (14C) polyethylene glycol (PEG) and (125) iothalamate (glofil) are reliable volume and glomerular markers in teleosts was tested. 2. PEG occupied smaller volumes than inulin and glofil in sea-water-adapted Salmo gairdneri. Ureteral clearances of PEG were about 22% higher than those of inulin and glofil, and urine-to-plasma ratios were significantly greater for PEG than for the other two markers. 3. After introduction into the urinary bladder the three macro-molecules appeared in the plasma, PEG at the lowest rates. 4. These observations indicate that mammalian glomerular markers can penetrate the bladder and possibly the ureters and renal tubules. Therefore, their clearances may not give a true measure of glomerular filtration rates in teleosts.


A method for recording the respiratory and hatching movements of the chick embryo.

1. An artificial air space was made in the narrow end of the pipped egg by separating the shell membranes from the shell. The respiratory and hatching movements of the embryo set up pressure changes within the artificial air space and these were recorded up until the moment when the chick emerged from the shell. 3. Random movements appeared to be inhibited during the period of hatching. 4. The ways in which the presence of the artificial air space might affect the embryo have been discussed.


Analysis of burst activity of the buccal ganglion of Aplysia depilans.

1. Certain nonlinear properties of molluscan neurones suggest that network activity could be described in relation to nonlinear relaxation oscillators. 2. A specific example is fitted by the Van der Pol equation with an exponentially decaying damping coefficient, and changes in the associated energy and sensitivity are considered. 3. More precise details of the interaction pattern determined by analysis of a single cycle of burst activity, and it is shown that there are two states of activity, depending on the balance of presumed inhibitory components. 4. Previous results are discussed in relation to an overall decaying oscillation. 5. Changes in subcomponents of a cycle are described for decaying sequences and the constancy of synaptic interaction is demonstrated. The results are briefly discussed in relation to catastrophe theory and learning.


Activities of antennal and ocellar interneurones in the protocerebrum of the honey-bee.

1. Unit responses to olfactory and mechanical stimuli of the antennae, and illumination of the ocelli, were recorded extracellularly in the protocerebrum of the honey-bee. 2. Bimodal units responded both to antennal and to ocellar stimuli; antennal units responded to the former and the ocellar units to the latter. Some antennal units responded to olfactory stimuli (olfactory units), and others responded to mechanical stimuli (mechanical units). 3. Ocellar units in the brain showed phasic responses at the start and/or cessation of illumination. Six types of responses were found. 4. About two-thirds of the bimodal units showed the same type of response to stimulation of the antennae as to stimulation of the ocelli. Most of them showed excitation by each stimulus. 5. Bimodal units were distributed around the alpha-lobe in the protocerebral lobe, whereas the antennal and the ocellar units were widely distributed.  6. By turning off the ocellar illumination, background discharge frequency, and the pattern and magnitude of responses to antennal stimuli, were changed. The activities of the ocellar units were altered by inputs from the antenna. 7. It was postulated that antennal and ocellar inputs converge and interact with each other in the protocerebral lobe of the honey-bee.


Morphometric study of trout gills: a light-microscopic method suitable for the evaluation of pollutant action.

1. Methods are described for the morphometric estimation of parameters of the gill system of trout which are relevant to its function in gas exchange. The methods have been used with 1 mum sections viewed under the light microscope. 2. In particular the diffusion distances between water and blood are measured, which together with determinations of gill area, provide figures for the morphometrically estimated diffusing capacity. 3. The methods have been used to compare the diffusing capacity of gills from control fish and those treated in polluted waters. The concept of relative diffusing capacity (Drel) is introduced which enables comparisons to be made without the need to determine the absolute diffusing capacity. 4. Quantitative estimation of changes in relative volumes and surface areas of components of the secondary lamellae were determined, and employed to explain the possible anatomical causes of changes in Drel. 5. It is suggested that these methods can be of value in the comparison of the gills of fish treated in different waters.


The effects of transecting the IXth and Xth cranial nerves on hydromineral balance in the eel Anguilla anguilla.

The IXth and the Xth cranial nerves in Anguilla anguilla were transected, and the effects upon ion and water balance were studied in fresh water and sea water, and during transfer from fresh water and vice versa. In fresh water there is a slow demineralization due to an excess loss of Na and Cl ions. During freshwater to seawater transfer the eel survives only for 4-5 days. The fish do not drink and Na efflux does not increase enough to extrude excess ions. In sea water the glossopharyngeal and vagus nerves are necessary for the maintenance of the hydromineral balance. Denervation is followed by an increase in plasma ion concentrations. Na fluxes are not modified and increased water loss is not compensated by drinking. The rapid reduction of Na efflux during transfer from sea water to fresh water is not modified by denervation.


The different actions of chloride and potassium on postsynaptic inhibition of an isolated neurone.

Isolated  stretch receptor neurones from freshwater crayfish were examined in solutions containing different concentrations of chloride and potassium. In normal solution the inhibitory reversal potential (Eipsp) of this preparation was strictly negative with respect to the resting potential and even to the reversal potential of spike after-hyperpolarization. The time courses of resting potential and Eipsp following rapid solution change suggest that the current generating the IPSP is mainly carried by chloride ions and that the participation of potassium is very small. This has also been confirmed by the calculated conductances of the activated inhibitory membrane in the different solutions. The results add further evidence for an outwardly directed pumping of chloride ions which keeps the intracellular concentration of this anion at the low level necessary for hyperpolarizing inhibition.


The series elastic component and the force-velocity relation in the anterior byssal retractor muscle of Mytilus edulis during active and catch contractions.

1. The length changes of the anterior byssal retractor muscle (ABRM) of Mytilus edulis, following step changes in load, were studied at various phases of active and catch contractions produced by acetylcholine. 2. The load-extension curves of the series elastic component (SEC) were found to be scaled down in proportion to the isometric tension immediately before step changes in load, but remain unchanged irrespective of whether the ABRM was in active or in catch contraction. 3. In hypertonic solutions the compliance of the SEC was reduced in the same manner as that of the SEC in frog skeletal muscle. 4. These results seem to favour the linkage hypothesis for the catch mechanism, though the SEC in the ABRM is suggested to be composed not only of the cross-linkages, but also of the compliance of the myofilaments.


Flight energetics of sphinx moths: power input during hovering flight.

The energetic cost of hovering flight was measured in sphinx moths from five species. Mean power input per unit mass (Pi/M) varied from 237-2 W kg-1 in Manduca sexta (Subfamily:Sphinginae), mean body mass 1-2 X 10(-3) kg, to 327-9 W kg-1 in Deilephila elpenor (Subfamily: Macroglossinae) mean body mass 7-3 X 10(-4) kg. Mean Pi/M for the five species was inversely proportional to mean body mass and directly proportional to mean wing loading. For any given body mass, Pi/M was greater in Hyles lineata than in M. sexta. This difference is correlated with higher wing loading at any given mass in H. lineata. Energy expenditure per unit mass of thorax was 1018 W kg-1 in H. lineata and 694 W kg-1 in M. sexta. Within each of these species, Pi per unit mass of thorax does not vary with body mass. Power input data are compared with calculated power requirements based on momentum theory and blade-element theory of helicopter aerodynamics. Absolute efficiency, the ratio between calculated power requirements and measured energy expenditure, appears to vary directly with body mass. These data provide an energetic basis for observed correlates between thoracic temperature and flight effort in flying sphinx moths.


Flight energetics in sphinx moths: heat production and heat loss in Hyles lineata during free flight.

1. Mean thoracic temperature of free-flying H. lineata in the field and in the laboratory increased from about 40 degrees C at Ta=16 degrees C to 42-5 degrees C at Ta=32 degrees C. At a given Ta, thoracic temperature was independent of body weight and weakly correlated with wing loading. 2. The difference between abdominal temperature and air temperature increased from 2 degrees C at low Ta to 4-2 degrees C at high Ta. At a given Ta, the difference between Tab and Ta was positively correlated with thoracic temperature. 3. Oxygen consumption per unit weight did not appear to vary with Ta from 15 to 30 degrees C and was inversely proportional to body weight. 4. Thermal conductance of the abdomen (Cab) was greater than thermal conductance of the thorax (Cth) in still air and at wind velocities up to 2-5 m/s. In moving air at speeds approximating flight, Cth was twice as high as in still air. Under the same conditions Cab was 3-4 times as high as in still air. 5. Thoracic and abdominal conductance are inversely proportional to their respective weights. 6. These data are consistent with the hypothesis that thoracic temperature is controlled by regulation of heat loss. However, a heat budget derived from these data suggests that heat dissipation may not be sufficient to offset the decrease in passive cooling of the thorax at high ambient temperatures.


Osmotic and ionic regulation in different populations of the new zealand freshwater crayfish Paranephrops zealandicus.

1. Some features of the osmoregulatory mechanism are compared in four populations of Paranephrops zeal andicus White collected form freshwaters of different ionic concentrations. 2. Crayfish from freshwaters of ca, 2-0 mM-NaCl concentration show a sustained decrease in blood concentration of ca. 8% when placed in 0-2 mM-NaCl. 3. Populations from freshwaters of ca. 0-2-0-4 mM-NaCl show lower rates of net salt loss in distilled water and higher rates of net salt uptake form dilute NaCl solutions than do populations from freshwaters of ca. 0-8-2-0 mM-NaCl. 4. Renal salt losses over the first 24 h in distilled water account for ca. 18% of the total salt loss. 5. It is suggested that P. zealandicus from environments of lowest concentration shows a similar degree of adaptation to freshwater as do crayfish of the northern hemisphere. It differs in possessing a substantially higher blood concentration.


Elastic energy storage in primary feather shafts.

It is proposed that the kinetic energy of a pigeon's wing, in hovering or slow forward flight, is transferred to the air at the end of the downstroke by a mechanism involving temporary storage of additional energy in bent primary feather shafts. Estimates of the amounts of energy which can be stored and recovered in this way are compared with the requirements of the theory. The hypothesis is not rejected, as far as present evidence goes. If is is correct, high-velocity pulses of calculable magnitude should be detectable in the wake.


Electrical activity of the proventriculus of the polychaete worm Syllis spongiphila.

The straited myoepithelial cells of the proventriculus of Syllis spongiphila are composed of only one or two sarcomeres that may reach 40 mum in length. Experiments were performed to study some of their electrophysiological properties and their synaptic control. The mean resting potentials recorded in two different bathing media were 59-1 +/- 5-5 mV (S.D., n=91) and 62-5 +/- 6-3 mV (S.D., n=98). At rest the membrane potential is determined largely by permeability of the membrane to K+ ions, but the membrane is also permeable to other ions. On a semilogarithmic plot of membrane potential v. [K]o the mean slope of the data points from 9 to 90 mM-[K]o was 48 +/- 3 mV for a 10-fold change in [K]o. The anterior end of the animal was stimulated with a suction electrode to elicit activity of nerve fibres that innervate the proventriculus. Single indirect stimuli usually evoked hyperpolarizing or biphasic responses, and occasionally depolarizing responses, from the myoepithelial cells. The depolarizing synaptic potentials exhibited a faster time course than the hyperpolarizing ones. The rise time to peak ranged from 20 to 35 ms for simple depolarizations (n=32) and 25-75 ms for simple hyperpolarizations (n=103). Time to decay to half amplitude ranged from 20 to 55 ms for depolarizations (n=29) and 62-135 ms for hyperpolarizations (n=87). Low frequency (is less than or equal to 4 Hz) trains of indirectly applied stimuli elicited mainly hyperpolarizing responses; higher frequency (5-40 Hz) trains elicited complex responses composed of hyperpolarizations and depolarizations. Hyperpolarizations were selectively and reversibly abolished in chloride-free solutions. The reversal potential of the hyperpolarizing synaptic potential was -104 +/- 3 mV (S.D., n=8, 2 preparations). In calcium-free solution both hyperpolarizations and depolarizations were almost completely abolished. 4 mM-Mn2+ added to the bath almost completely abolished the depolarization but not the hyperpolarization. It was not clear whether Mn2+ acted at the presynaptic membrane, the postsynaptic membrane or both. The myoepithelial cells are electrically coupled. The mean space constant of five preparations was 0-52 mm (range 0-40-0-66 mm).


The cardiac responses to shell opening and closure in the bivalve Arctica islandica (L.).

Shell closure in Arctica islandica is followed by an exponential decrease in the oxygen tension of the mantle cavity water and is accompanied by an initial increase in heart rate which is followed at lower oxygen tensions by a bradycardia. Prior to shell opening there is a slight increase in heart rate before any movement of the shell valves can be detected. However, once the shell opens and pumping activity recommences there is a rapid increase in heart rate, often to levels above normal. Perfusion of the mantle cavity with water of high and low oxygen tension resulted in the cardiac responses normally associated with shell opening and closure. Recordings of the PO2 of the blood in the ventricle, made simultaneously with cardiac recordings, showed that the changes in heart rate were recorded only after the PO2 of the blood had changed. These experiments suggest that changes in the PO2 of the mantle cavity water may be primarily responsible for the cardiac responses to shell closure in Arctica.


Anatomy and development of the somatic musculature of the nematode Ascaris.

The musculature of the nematode Ascaris has been studied by the examination of serial sections by light and electron microscopy. The muscle cells of nematodes are unusual in that they send branches to the neurones in contrast to the more usual situation in other animals where neurones send processes to the muscles. The neuromuscular synapses are made at the ends of the arms. Muscle cells receive multiple innervations and perform integration of the combined inputs. The action potentials are initiated near the ends of the arms so each arm acts as an integrative centre. It is shown that it is common for a muscle cell to have several arms, raising the possibility that each arm may integrate different combinations of neuronal inputs. In the second larval stage the total number of muscle cells is 83. The adult has approximately 5 X 10(4) muscle cells. The very striking increase in cell numbers of the musculature is not matched by a corresponding increase in the number of cells in the nervous system. A model for the way in which a small number of neurones can co-ordinate the activity of an increasing population of muscle cells is presented.


The effect of caffeine on excitation-contraction coupling in skeletal and smooth muscle.

1. For cockroach skeletal muscle, 2 mM caffeine considerably lowered the mechanical threshold without affecting the membrane potential. Constractures were induced by 8-10 mM caffeine. 2. In rat ileal smooth muscle, 1-10 mM caffeine inhibited spontaneous contractile behaviour, abolished spike activity and reduced KCl-induced contracture tension. 3. Enhanced spike activity associated with the KCl-induced phasic contraction was abolished by caffeine, the degree of caffeine-induced relaxation being proportional to the concentration employed. These relaxations were not accompanied by membrane hyperpolarization. 4. The present results accord with previous work which has shown that caffeine increases myoplasmic free calcium in the skeletal muscle and lowers it in the smooth muscle. It is suggested that caffiene releases bound calcium in the former muscle and promotes binding in the latter. 5. It is further suggested that in the smooth muscle caffeine may reduce the membrane permeability to calcium.


Immunologic characterization of the membrane-bound collagen in normal human fibroblasts: identification of a distinct membrane collagen.

Collagen, the major extracellular matrix protein, is also a membrane protein. Two types of collagen are detected on the normal human fibroblast membrane in culture, type I collagen and a new immunologically and chemically distinct collagen, type M (membrane) collagen. Antibodies to type M collagen elicited complement-mediated cytotoxicity, which could be blocked by pretreatment of the cells with bacterial collagenase or the antibody with type M collagen. Pretreatment of the cells with other proteolytic enzymes or the antibody with type I collagen or type III collagen had no effect on this complement-mediated cytotoxicity. Although type I collagen is the major collagen synthesized by normal human fibroblasts type M collagen may be the major cell membrane collagen and may be a major cell membrane component.


Variation and control of specific antigen-binding cell populations in individual fetal mice.

To determine the extent and nature of individual variation in the development of specific antigen-binding cells, the numbers of cells specific for each of two antigens in the spleens of individual random-bred Swiss-L and inbred CBA/J and BALB/c fetal mice were measured as a function of spleen size. For Swiss-L fetuses, the ratio of antigen-binding cells to nucleateated cells varied more than would arise from sampling fluctuation. For each inbred strain, however, the number of cells specific for a given antigen was a constant proportion of the total number of nucleated cells within sampling error. These proportions varied from antigen to antigen, and from strain to strain. The ratio of the proportions of cells specific for the two antigens, however, differed no more from CBA/J to BALB/c mice than would be expected in repeated samples of cells from the spleen of a single fetus. These results confirm at the level of the individual fetus the uniform pattern of development seen for populations of fetuses. They reveal a surprising precision in the proliferation of specific antigen-binding cell populations and suggest that the development of these cells may be subject to strong genetic controls.


Genetic control of specific immune suppression. III. Mapping of H-2 complex complementing genes controlling immune suppression by the random copolymer L-glutamic acid50-L-tyrosine50 (GT).

Earlier studies from our laboratory demonstrated that the terpolymer of L-glutamic acid, L-alanine, and L-tyrpsine (GAT) stimulated the development of T cells capable of specifically suppressing the antibody responses in vivo and in vitro of nonresponder strains (bearing the H-2(s), H-2(q), and H-2(p) haplotypes) to GAT complexed with an immunogenic carrier, methylated bovine serum albumin, MBSA (1,2). We then extended these findings to another antigen, the copolymer of L-glutamic acid and L-tyrosine (GT). None of 19 inbred or congenic resistant mouse strains developed antibody responses to GT after immunization with this synthetic polypeptide in adjuvants. All the strains investigated, however, developed IgG plaque-forming cells (PFC) primary responses to GT complexed with MBSA (3). This permitted us to determine that: (a) preimmunization with GT suppressed the response to GT-MBSA in certain but not in all strains; (b) the suppression could be transferred by thymocytes and spleen cells from GT-primed animals; (c) the development of GT-specific suppressor cells is under dominant control of H-2- linked gene(s) which have been designated specific immune suppressor genes (Is genes); (d) the Is genes are antigen specific since GAT-MBSA responses are suppressed by GAT in strains carrying the H-2(q) haplotype, while GT-MBSA responses are not suppressed by the related polymer GT in these same strains (3,4). The experiments reported in this study map the Is genes responsible for GT-specific suppression within the H-2 complex. The data indicate that the K and D loci are not concerned with GT-specific suppression, and that this phenomenon is controlled by complementing or interacting genes which map on either side of cross-over events between the IB and IC subregions.


[Clinical-chemical diagnosis of poisoning].

There is a disparity between the number of reported cases of poisoning and the number of chemical analyses performed for the identification and quantitative determination of a particular poison. The aim of the workshop conference was to clarify the extent to which different clinics possess or require the necessary facilities for the investigation of poisons. The following summary of 16 lectures and accompanying discussion puts into perspective the present state of clinical toxicological analysis. Guide lines for the further development of clinical-toxicological analysis are formulated in the final discussion, where a plan is proposed for the incorporation of toxicological analysis into clinical chemistry.


The use of aldehyde dehydrogenase to determine H2O2 -producing reactions. I. The determination of the uric acid concentration.

The sequence of reactions catalyzed by uricase, catalase and aldehyde dehydrogenase for determination of the uric acid concentration was evaluated for human serum and urine samples. More than 60 substances were tested for possible interferences. Alcohol dehydrogenase, formaldehyde and homogentistic acid can disturb the proposed assay, but at concentrations which are not usually encountered in human serum or urine. In the presence of protein at least 99% of the uric acid was recovered.


[The feigned release of cell enzymes. Distribution and transport of cell enzymes within the extracellular space. I (author's transl)].

A sudden increase of enzyme activities in plasma is not necessarily due to a release of enzymes from damaged cells. Three experimental models were used to demonstrate that acute alterations of enzyme activities, as much as +/- 15%, can be caused by fluid-shifts between the intra- and extravascular compartments. Venous occlusion of the forearm by tourniquet produces an increase of the intravascular hydrostatic pressure and subsequently results in a decrease of the plasma volume distal to the tourniquet. Because enzyme molecules are not freely diffusible across the capillary membrane the enzymatic activity increases proportionally to the decrease of plasma volume. Changes in the body posture are accompanied by changes in plasma volume and similarly by alterations in the concentration of plasma-proteins and by alterations in intravascular enzyme activities. Increased enzyme activities in plasma during strenuous physical effort are due chiefly to a concentration of macromolecules within the intravascular space because of a decrease in plasma volume and not to a release of enzymes from hypoxic muscle cells. During recovery after termination of the exercise there is a second and longer lasting increase in enzyme activities in plasma which could be related to a release of enzymes from injured cells. It is suggested that some of these changes could be due to an increase in lymph flow and thereby an increasing transport of enzymes from the interstitial to the intravascular compartment.


[Cell enzymes in lymph. Distribution and transport of cell enzymes within the extracellular space. II (author's transl)].

Enzyme patterns were measured in the lymph of the thoracic duct of the dog and in the intestinal lymph of the rat. Those patterns were compared to the corresponding activities in blood plasma. From the results it is concluded that under physiological conditions cell enzymes are released into the interstitial space and from there are transported via the lymph into the intravascular space. Only enzymes with a low molecular weight such as myokinase are able to penetrate the capillary membrane, thereby reaching the plasma without being transported exclusively by the lymph. There is a close relationship between the molecular weight of enzymes and their plasma/lymph ratios. In the rat the enzyme patterns in mesenteric lymph nodes and in intestinal mucosa and muscularis (duodenum as well as ileum) were also determined. No direct correlation between those intracellular patterns and the enzyme patterns in the intestinal lymph could be established. The significance of lymph and lymph flow for clinical enzymology is discussed with respect to physiological and pathological conditions. High sensitivity of diagnosis by means of enzyme measurements in plasma can be achieved only if the capillary permeability in the injured organ is high and/or the lymph flow from the organ is not restricted by the injury.


[Distribution of intravenously injected enzymes of heterologous, homologous and autologous origin. Distribution and transport of cell enzymes within the extracellular space. III (author's transl)].

The disappearance rates of intravenously injected enzymes of heterologous, homologous and autologous origin were determined in rats. Within four hours after administration, the activities show an exponential decline, that is either mono- or biphasic. The constant of the exponential function is a measure of the capillary permeability. In the case of biphasic disappearance this holds true only for the first slope, whereas the second one represents the elimination of active enzyme molecules from the extracellular space. If the decline in enzyme activity is monophasic the elimination of those enzymes from the interstitial space is limited by the permeability of the capillary membrane. Enzymes of homologous and autologous origin (extracts of liver or muscle) show a close correlation between their molecular weights and their rates of distribution within the extracellular compartment. For heterologous enzymes (crystallized) such a correlation could not be found. Possible causes for these differences in distribution are discussed. Heterologous and/or crystallized enzymes seem not to be suited for studies on the distribution of cell enzymes within the extracellular space. After enzymes are released from injured cells they undergo the processes of distribution, transport and elimination which are superimposed. The effects of the distribution and transport of enzymes on the results of clinical studies on enzyme elimination are discussed. It seems questionable at this point to assume that from the elimination rate of enzymes and their actual plasma activity one can account for the amount of enzymes originally released from injured cells.


[Plasmapheresis as an experimental model for studies on the extracellular distribution of enzymes. Distribution and transport of cell enzymes within the extracellular space. IV (author's transl)].

The rate of distribution of cell enzymes between the intravascular and extravascular space was studied, following a sudden decrease of enzyme activities in plasma. This rapid decrease of enzyme activities was achieved in rats by a rapid exchange of the blood with a twofold volume of a suspension of homologous erythrocytes in isoosmolar bovine serum albumin solution. After this plasmapheresis, the activities of seven cell enzymes in the plasma were decreased to 14 to 22% of their original values. The subsequent increase in activities showed different kinetics, depending on the enzyme. After 120 min, creatine kinase had reached the starting activity; malate dehydrogenase and aldolase reached their original activities after 180 min. Aspartate aminotransferase, glutamate dehydrogenase, alanine aminotransferase and pyruvate kinase increased more slowly and they had still not reached their starting values after 240 min. Repetition of the plasmapheresis after 90 min had no obvious effect on the kinetics of the subsequent activity increase. During the first minutes after plasmapheresis the adjustment of the activity equilibrium between the interstitial and the intravascular compartments depends mainly on the capillary permeability. It is therefore possible to determine half-life constants for the distribution of enzymes within the extracellular space. The constants for malate dehydrogenase and aldolase are almost identical with those determined by intravenous injection, whereas there are discrepancies in the constants for the remaining enzymes. The constants for pyruvate kinase and glutamate dehydrogenase are significantly lower, while those for aspartate aminotransferase, alanine aminotransferase and creatine kinase are significantly higher, than those determined after intravenous injection. Possible reasons for these differences are disucssed.


[The fecal pigment (author's transl)].

The hypothesis is developed that the fecal pigment constitutes a copolymer of bacterially produced monomers. The possible monomers (oxidation products mainly of urobilinogen and hydrolysis products thereof) and the principles of their polymerization are defined.


The ICSH reference method for serum iron assay: recommendation for a viable automated alternative.

A viable alternative to the ICSH reference method for serum iron assay is proposed where automated batch analysis is required. The introduction of Ferrozene into contemporary automated methodology makes this possible. The Donnan effect on membrane dialysis has been resolved by observing the fate of aqueous and protein matrices inoculated with 59FeCl3 as they leave the system.


[Suitability of the Weidemann test for galactose in mass screening (author's transl)].

With slight practical modification, especially in the preparation of blood samples on filter paper in place of liquid blood samples, it was possible to adapt the determination of galactose dehydrogenase (Weidemann, G. (1971), this Journal 9,527) to mass screening. The technique is described, and the first results are briefly discussed and compared with those obtained over the years in our screening program with proven the Guthrie test (1): The dehydrogenase test is much quicker and shows a higher substrate specificity than the Guthrie test (duration 2 hours compared with 44 hours; false positive results of 16.87 mmol/l galactose or higher 1:42231 compared with 1:3519). It is, however, less sensitive (16.87 mmol/l compared with 1.69 mmol/l galactose), so that a combination of both tests would seem appropriate for the mass screening of new borns.


Structural units and the redintegrative power of picture fragments.

We suppose that line drawings are perceived and represented in memory as a hierarchy of related parts and subparts, as dictated by Gestalt laws like common direction and spatial proximity. Therefore, a figure fragment comprising a natural part of an orginally studied pattern should serve as a strong retrieval cue for redintegrating memory for the pattern, whereas an equally large fragment suggesting either no units of misleading units should lead to poorer recall. This was confirmed in an experiment in which subjects studied 33 nonsense line drawings; recall of each was tested with good, mediocre, or bad (misleading) fragments of the original patterns. Good cues had about five time more redintegrative power than bad cues. A second experiment testing multiple-choice recognition memory showed that subjects confused an originally studied pattern about four times as often with a structurally similar distractor as with a structurally dissimilar distractor (which had an equal-sized change). Thus, memory cuing by fragments and memory confusions with slightly altered distractors indicate the significant constitutents of a figure.


Recognition gradients for random shapes following distinctive or equivalent verbal association training.

The effect of distinctive and equivalent verbal label training on a subsequent test of recognition memory for random shapes were assessed. Shape continua, systematically relating the labeled shapes, were used in the memory test so that gradients of recognition memory were obtained. Distinctive-nonrepresentative-label training produced symmetrical recognition gradients with a single mode at the correct target shape. Equivalent-label training produced symmetrical gradients that were as steep as the distinctive-label gradients, but the mode of the equivalent-label gradients was shifted to a distractor shape that varied from the target in the direction of the equivalent-label shape. The results offered support to a Gestalt/configurational account of the effects of verbal labels on memory for form, but the data were also consistent with an extension of Ellis' conceptual coding hypothesis. It was concluded that, rather than being a competing alternative account, the conceptual coding hypothesis may be viewed as an updated, more analytic statement of the older Gestalt view.


Hormone induction of specific protein synthesis in midpregnant mouse mammary cell culture.

Monolayer primary cell cultures of midpregnant mouse mammary cells were subjected to hormone stimulation under strictly defined conditions. Hormonal response was measured in terms of increase in rate of synthesis of mouse casein, using a double antibody precipitation technique. Cells stimulated by insulin plus prolactin plus cortisol plus estradiol plus progesterone showed a marked increase in rate of mouse casein synthesis over the controls. This specific product synthesis, which remains inducible in these cells for at least ten days, was detected either by labelled phosphoric acid or labelled amino acid incorporation. The mouse casein synthesized was identical, as judged by the identification techniques used, to that of mouse milk. Mouse midpregnant mammary explants in organ culture require insulin plus prolactin plus cortisol to express their full lactogenic capabilities. Nevertheless, when the same cells are dispersed and grown in monolayers they require ovarian steroids to elicit a lactogenic response as shown in this study. Ovarian steroids, therefore, are necessary in lactogenesis, although the fundamental nature of their action remains to be established.


The fine structural development of preimplantation mouse parthenotes.

The normality of the preimplantation development of 2-cell to expanded blastocyst stage mouse parthenotes, derived from oocytes activated in vivo, or in vitro, has been assessed at the fine structural level. Major changes in the organization of the cellular organelles, i.e., nucleoli, mitochondria, ribosomes, RER and junctional complexes, follow the same developmental sequences observed in embryos obtained from normally fertilized oocytes. One difference between parthenotes and controls is the scarcity of crystalloid bodies in parthenotes at the blastocyst stage. Because the embryos examined in this study had been cultured in vitro, in a simple salt and albumin medium in the absence of maternal influences, our observations on parthenotes indicate that developmental, preimplantation changes in the subcellular organization of the embryo do not require the continued presence of "maternal" factors or the participation of the paternal genome.


The effects of acetylcholine, biogenic amines and other vasoactive agents on the cardiovascular functions of the Eel, Anguilla japonica.

The blood pressure in the cardinal vein, cardiac chambers and ventral and dorsal aortae have been recorded from conscious eels in water. At low doses, acetylcholine reduced the heart rate but increased the transbranchial differential blood pressure. The effects were abolished by atropine but not by tubocurarine. At doses in excess of 0.1 mug/kg, a secondary rise in arterial blood pressure was observed which could be abolished by bretylium, phentolamine or phenoxybenzamine. Catecholamines did not affect the heart rate although a transient bradycardia due to reflex inhibition could be observed with adrenaline and noradrenaline. Catecholamines increased the cardiac contractile force through an alpha-adrenergic mechanism which was blocked by phentolamine but not by propranolol. The relative potency was noradrenaline greater than adrenaline greater than isoprenaline. A beta-adrenergic receptor located in the branchial circulation led to vasodilation and decrease in transbranchial differential pressure. Both alpha-(vasoconstriction) and beta-(vasodilation) adrenergic receptors were present in the systemic circulation. Dopamine, 5-HT, GABA and bradykinin caused bradycardia abolishable by vagotomy or atropine treatment. Angiotensin II was hypertensive but did not affect the heart rate nor the transbranchial differential pressure. Tyramine caused release of endogenous catecholamines. With repeated doses, tachyphylaxis to the drug was observed. Histamine was without any obvious cardiovascular effects in the eel.


Sperm concentration dependency in the fertilization and zonae sperm binding properties of mouse eggs inseminated in vitro.

Sperm penetration of zonae and fertilization of mouse eggs in vitro was studied as a function of sperm concentration over the range 10(3)-10(6) cells/ml. Maximal fertilization was obtained at 10(5) sperm/ml with markedly reduced levels seen at lower concentrations. Eggs inseminated at low sperm concentrations were, however, characterized by the absence of multiple sperm penetrations of their zonae and by the retention of an intact cumulus oophorus during culture. Penetration levels were similar in eggs inseminated with and without an intact cumulus, although increases in supernumerary and supplemental sperm were observed with partly denuded ova. The distribution of sperm found within eggs inseminated in vitro was compared with a distribution predicted by chance alone. The similarity in observed and expected distributions indicated that a functional zona reaction was absent in eggs inseminated in vitro. Sperm binding to zonae of cumulus-free unfertilized mouse eggs was shown to be related to sperm concentration over the range 10(3)-10(6) cells/ml. Zonae sperm binding sites, while too numerous for accurate quantitation, exceeded 100 per zona. The interrelationships between sperm penetration of and sperm binding to the zonae of cumulus-free eggs were examined. At low sperm concentrations, the ratio of sperm/zonae with bound sperm to sperm/penetrated egg approached one, although the total number of bound sperm exceeded the total number of penetrating sperm. That proportion of cells in a preincubated epididymal sperm suspension, capable of binding to the zona was determined and employed in an estimation of the extent of sperm capacitation.


The role of the copulatory plug in reproduction of the guinea pig.

Two methods of artificial insemination and removal of copulatory plugs were used to investigate the role of the plug in the guinea pig. In addition, the effectiveness of the copulatory plug in blocking the passage of spermatozoa from the second mating was tested in albino females, where coat color was used as a genetic marker. Thirteen female guinea pigs that were either in proestrus, estrus, or metestrus, and inseminated with freshly collected copulatory plugs containing living spermatozoa, did not conceive. In a group of six females from which the copulatory plus was immediately removed, five conceived. Of nine estrous females artificially inseminated, five conceived. In five albino females, copulatory plugs from albino males completely blocked spermatozoa deposited by colored males, and 20 offspring, all albino were born. In a second group of four albino females where the plugs of albino males were removed prior to copulation with colored males, resulting litters were sired by either male or a combination of both males.


The influence of the otic capsule in ambystomid skull formation.

In the absence of the otic capsule, or in the presence of capsular materials of varying volume or placement, the bones and cartilages of the contiguous skull showed several sorts of responses. A. The parietal and squamosal bones, and possibly the parasphenoid bone and parachordal cartilage apparently used the capsule as a substrate, spreading over its surface. B. The parietal, squamosal, and exoccipital bones, and the quadrate cartilage were displaced when otic capsule material was absent or oversized. C. The squamosal bone developed at first independently of the capsule but was modified in its shape and size by the capsule in later, possibly inductive, response. D. Stresses resulting from paired otic capsules of unequal size bent the parasphenoid bone and the parachordal cartilage through angles of predictable direction relative to the notochord. E. The paired exoccipital bones developed at different rates when one otic capsule was absent or oversized. The results obtained following manipulation of the otocyst indicate the major role of extrinsic (epigenetic) parameters in normal skeletogenesis and emphasize an apparent discrepancy between the normal and potential expansion of a bone.


Differential gene expression in multilocus isozyme systmes of the developing green sunfish.

The patterns of expression of eight multilocous isozyme systems were investigated in the differentiated adult tissues and the early embryonic stages (0-210 hours after fertilization) of the green sunfish, Lepomis cyanellus. Enzymes encoded by approximately 23 gene loci were resolved by starch-gel electrophoresis and detected by specific histochemical staining. The developmental patterns of these isozyme systems appear to be the result of the diffential expression of the multiple gene loci. Isozymic forms of glucoseophosphate isomerase (GPI-A2), malate dehydrogenase (MDH-A2), and creatine kinase (CK-C2) were present in most differentiated tissues, in the unfertilized eggs, and in all stages of embryonic development. Closely homologous forms of these isozymes (GPI-B2, MDH-B2, and CK-A2) were expressed predominantly in skeletal muscle and were first detected at around the time of hatching (38-42 hours). The similar temporal and spatial patterns of gene expressions for the GPI, LDH, MDH, and CK loci suggest that the duplicates loci encoding enzymes, diverged in their regulation to patterns of differential gene expression which are similar for each enzyme system.


Stages of tail regeneration in the adult newt, Notophthalmus viridescens.

Five distinguishable stages of tail regeneration in the adult newt have been established. The stages are based on external morphological changes and internal histological characteristics rather than chronological age of the regenerate.


Regeneration from different levels along the tail of the newt, Notophthalmus viridescens.

Some aspects of the influence of position on regeneration have been examined by comparing regeneration from different levels along the newt tail. Tails amputated such that either three-fourths one-half or one-fourth of the tail was removed pass through the same morphological and histological stages at the same times after amputation. In tails amputated at these three different levels, the rate of elongation of regenerates from more proximal levels is greater than that of regenerates from more distal levels. The total lengths of regenerates from different levels are proportional to the lengths of tail removed by amputation. Furthermore, the number of vertebrae formed in a tail regenerate is directly proportional to the number of vertebrae removed by amputation. When a tail blastema is transplanted to a more proximal level tail stump, intercalary regeneration between the stump and transplant occurs and the resulting regenerate has a complement of vertabrae appropriate to its new level along the tail. The results indicate that position along the appendage does not influence the developmental sequence of events of regeneration, but that it does influence the rate of growth and the structures to be replaced.


Retention of ova in oviducts of senescent mice and hamsters.

Young (3-5 months of age) and senescent (12-17 months of age depending on the species) female mice, hamsters and rats were mated with young mature males and examined for numbers of degenerating ova. Young female mice, hamsters, rats and senescent rats exhibited normal numbers of ova following ovulation and, in general, normal numbers of blastocysts before implantation. In contrast, on the morning of ovulation some senescent mice and hamsters exhibited degenerating ova in the isthmus or isthmic-utero-tubal region of the oviduct, while normal ova were found in the ampulla. Degenerating ova were also located in the uterine horns of one mouse and hamster before implantation (day 3 of preganacy). Another hamster at the same stage of pregnancy exhibited 24 degenerating ova and nine blastocysts, all of which remained in the oviducts except for one blastocysts recovered from the uterus. In a previous study (Parkening and Soderwall, '75) a histological examination of the number of copora lutea from ovaries removed from senescent female hamsters whose oviducts contained large numbers of degenerating ova indicated the deteriorating ova were not ovulated following mating. Why ova from the previous unmated estrous cycle(s) remain in the oviducts of some senescent mice and hamsters remains to be determined.


Abnormal morphagenesis of feather structure and pattern in the chick embryo integument. I. Macroscopic description.

The development of feathers in embryos from a profusely feathered line derived from a homozygous scaleless mutant stock was compared with that of embryos from a standard White Leghorn stock. The time of appearance of feather primordia, their structure and their arrangement all were altered in mutant embryos. Unit structures ranging in size from hillocks of 300 mu diameter (the size of normal primordia) to ridges 8 mm long were found in varying numbers in the different tracts of the mutant embryos. the hexagonal pattern characterizing feather primordia in normal embryos was disrupted in scaleless high line embryos. Differential growth and morphogenetic sculpting, as evidenced by the appearance of clefts, generate the form of and subdivide the variable shaped unit structures of the mutant as they elongate. Selection for high feather number was successful in dramatically increasing the total amount of feathering but the absence of coordinate controls of pattern and feather structure development led to the aberrant arrangement of tracts and of structures within the tracts. The basic pattern thus appears to have been destroyed by the scaleless mutation, and the alteration of the phenotype accomplished by selection has not apparently restored its control.


Stromal induction and specification of morphogenesis and cytodifferentiation of the epithelia of the Mullerian ducts and urogenital sinus during development of the uterus and vagina in mice.

Homotypic and heterotypic recombinations were preapred with trypsin-separated epithelium and stroma from uterus of 1- to 9-day-old and vagina of 2- to 150-day-old mice. Growth of homotypic recombinants in adult female hosts resulted in normal uterine and vaginal morphogenesis. Heterotypic recombinants composed of uterine stroma and vaginal epithelium (VE) usually formed uterus, while recombinants composed of vaginal stroma and uterine epithelium (UE) usually underwent vaginal morphogenesis. The developmental responses of these heterotypic recombinants was age-dependent. Epithelia (UE and VE) from mice two to five-days old were responsive to stromal induction. However, from days 5 to 9 postpartum a progressive loss in competence was observed in both epithelia, and vaginal epithelium nine or more days old was unresponsive to heterotypic inductors. Inductive activities of uterine stroma were demonstrated in 2- to 7-day-old neonates and of vaginal stroma in 2- to 150-day-old mice. These results indicate that establishment of the regional specification of Mullerian and sinus epithelium during uterine and vaginal morphogenesis is due to inductive activities of the stroma.


Ionophore A23187 induces acrosome reactions in sea urchin and guinea pig spermatozoa.

Ionophore A23187, in the presence of extracellular Ca+2, induces a morphologically normal acrosome reaction in sperm of the sea urchin and precocious acrosome reaction and activation of guinea pig sperm. Increased membrane permeability to Ca+2 is responsible for initiating the acrosome reaction in both sea urchin and guinea pig sperm. In sea urchin sperm, the permeability change is brought about by egg jelly, whereas in the guinea pig sperm it accompanies capacitation.


The effect of hypothalamic thermal stimulation on respiration in the turtle.

Cumulative Oxygen Consumption (VO2) and Oxygen Consumption per Unit Time were measured for fresh water turtles (Pseudemys scripta elegans) as hypothalamic stimulation was applied. Stimulation was provided by means of a thermode at 9-2o C (cold), 27o C (sham), and 55-60 degrees C (HOT). A statistically significant increase in mean cumulative oxygen consumption was noted for hot stimulation as compared to control value. A less dramatic but significant decrease in mean cumulative oxygen consumption was noted for cold stimulation. Both the increase and decrease, for hot and cold application, respectively, were proportional to the temperature of the thermode. Mean cumulative oxygen consumption per unit time did not show any corresponding statistically significant increase or decrease for hot or cold stimulation, respectively. Application of thermode at room temperature (sham) produced no significant change in respiration. This study indicates that reptiles have evolved a neural input mechanism sensitive to temperature change before mammalian and avian endothermy had developed.


Some respiratory characteristics of the blood of four antarctic fishes.

Oxygen equilibrium curves of blood from four antarctic fishes were obtained at subzero temperatures. Oxygen contents were measured directly and the results on two of these fishes agreed favorably with previous studies in which oxygen electrodes were used.


Synaptic organization and ionic basis of on and off channels in mudpuppy retina. I. Intracellular analysis of chloride-sensitive electrogenic properties of receptors, horizontal cells, bipolar cells, and amacrine cells.

Intracellular recordings from receptors, horizontal cells, bipolars, and amacrines have been carried out in the perfused mudpuppy eyecup. The introduction of a chloride-free (c-f) medium results in initial transient potential changes in many cells followed by a slow loss of light-evoked activity of the depolarizing bipolar, the horizontal cell, and the on depolarization of amacrine cells. The hyperpolarizing bipolar remains responsive to light stimulation in a c-f medium, but the antagonistic surround mechanism is abolished. These effects are reversible after returning to a normal ionic medium. The results of this study provide insight into the retinal connections which underlie ganglion cell receptive field organization. It is concluded that the depolarizing bipolar is excitatory to on ganglion cells and is also the pathway for on-excitation of on-off cells. The hyperpolarizing bipolar mediates the off discharge of off and on-off cells. Amacrine cells receive input from both depolarizing and hyperpolarizing bipolar cells. These findings raise the possibility that transmembrane movements of chloride ions are critical for the light responsiveness of horizontal and depolarizing bipolar cell activity.


Synaptic organization and ionic basis of on and off channels in mudpuppy retina. II. Chloride-dependent ganglion cell mechanisms.

Extracellular ganglion cell recordings in the perfused mudpuppy eyecup show that a chloride-free (c-f) perfusate abolishes the center and surround excitation of on-center cells, the surround excitation of off-center cells, and the on discharge of on-off cells. These changes in ganglion cell receptive field organization are anticipated in view of the effects of a c-f environment on the neurons which are presynaptic to the ganglion cells. However, chloride-dependent inhibitory postsynaptic (IPS) responses have been observed in on-off ganglion cells. These inhibitory postsynaptic potentials (IPSP's) are preceeded by (ESPS's) exitatory postsynaptic potentials and are apparently mediated by amacrine cells. The light-activated hyperpolarization of off cells is not the result of a chloride-dependent IPSP and probably results from disfacilitation.


Synaptic organization and ionic basis of on and off channels in mudpuppy retina. III. A model of ganglion cell receptive field organization based on chloride-free experiments.

A chloride-free environment produces selective changes in the retinal network which include a separation of on and off channels. The identification of chloride-sensitive and insensitivie neuronal activity permits identification of some of the connections and intervening polarities of synaptic interactions which are expressed in ganglion cell receptive field organization. These experiments support previous suggestions that surround antagonism is dependent on horizontal cell activity. In addition they suggest a model of the neuronal connections which subserve on-center, off-center, and on-off ganglion cells. Experimental tests of the on-off ganglion cell model favor the idea that this type of ganglion cell receives inhibitory input from amacrine cells and excitatory activation from depolarizing and hyperpolarizing bipolar cells.


Patterns of proteins synthesized in the R15 neuron of Aplysia. Temporal studies and evidence for processing.

The time-course of changes in the pattern of newly synthesized proteins in the R15 neuron of the parietovisceral ganglion of Aplysia californica has been studied at 14 degrees C. 5% polyacrylamide gels containing sodium dodecyl sulfate (SDS) have been used to separate newly synthesized (leucine-labeled) proteins from the neuron. We have demonstrated that the pattern of newly synthesized proteins from the R15 neuron does not change significantly if 5-h pulses of labeled leucine are given during the first 72 h of in vitro incubation of the excised ganglion. However, the level of leucine incorporation begins to decline somewhere between 17 and 43 h after the ganglion is isolated; at 43 and 69 h the levels of incorporation fell to 29 and 10% of the initial level, respectively. A number of conclusions have been drawn from the use of a sequential, double-label type of experiment in the same cell. There is processing of SDS-soluble, 12,000-dalton (12k) material to 6,000-9,000-dalton (6-9k) material. These materials are the two major peaks on gels after long labeling periods and together account for about 35% of all newly synthesized proteins. After synthesis of 12k material, there is a gradual disappearance of 12k (half-life about 8 h) and simultaneous appearance of 6-9k material on the gels, as the postsynthesis "chase" period of ganglia incubation is increased. The processing of 12k to 6-9k material occurs even in the presence of anisomycin, a protein syntehsis inhibitor, during the chase period. While the rate of 12k to 6-9k conversion can vary from cell to cell, it appears to remain consistent within, and is characteristic of, any individual R15. We detect no circadian rhythm in either the rate of 12k synthesis or the rate of 12k to 6-9k processing with 5-h label periods. These results are discussed in relation to the roles of 12k and 6-9k material in the R15 neuron.


Inactivation of monazomycin-induced voltage-dependent conductance in thin lipid membranes. I. Inactivation produced by long chain quaternary ammonium ions.

The voltage-dependent conductance induced in thin lipid membranes by monazomycin undergoes inactivation upon the introduction of quaternary ammonium ions (QA) having a long alkyl chain (e.g. dodecyltrimethylammonium [C12]) to the side containing monazomycin. That is, in response to a step of voltage the conductance rises to a peak and then falls to a much lower steady-state value. We demonstrate that the basis of this phenomenon is the ability of QA to pass through the stimulated membrane and bind to the opposite surface. As a consequence, the surface potential on that side becomes more positive, thus reducing the voltage across the membrane proper and turning off the monazomycin-induced conductance. Because the flux of QA through the membrane increases linearly with conductance, we believe that these ions pass through the monazomycin channels. QA permeability increases with alkyl chain length; remarkably, in spite of its much larger size, C12 is about 150 times more permeant than K+. It appears, therefore, that there is a hydrophobic region of the cahnnel that favors the alkyl chain; we propose that this region is formed by the hydrophobic faces of the monazomycin channels in lipid bilayers to QA inactivation of potassium channels in the squid giant azon, and suggest that there may be a common structural feature for the two channels. It is possible that some of the inactivation phenomena in excitable cells may arise from local field changes not measurable by the recording electrodes.


Inactivation of monazomycin-induced voltage-dependent conductance in thin lipid membranes. II. Inactivation produced by monazomycin transport through the membrane.

At sufficiently large conductances, the voltage-dependent conductance induced in thin lipid membranes by monazomycin undergoes inactivation. This is a consequence of depletion of monazomycin from the membrane solution interface, as monazomycin crosses the membrane to the opposite (trans) side from which it was added. The flux of monazomycin is directly proportional to the monazomycin-induced conductance; at a given conductance it is independent of monazomycin concentration. We conclude that when monazomycin channels break up, some or all of the molecules making up a channel are deposited on the trans side. We present a model for the monazomycin channel: approximately five molecules, each spanning the membrane with its NH3+ on the trans side and an uncharged hydrophilic (probably sugar) group anchored to the cis side, form an aqueous channel lined by--OH groups. The voltage dependence arises from the flipping by the electrical field of molecules lying parallel to the cis surface into the "spanned state;" the subsequent aggregation of these molecules into channels is, to a first approximation, voltage independent. The channel breakup that deposits monomers on the trans side involves the collapsing of the channel in such a way that the uncharged hydrophilic groups remain in contact with the water in the channel as they close the channel from behind. We also discuss the possibility that inactivation of sodium channels in nerve involves the movement from one side of the membrane to the other of the molecules (or molecule) forming the channel.


Damped oscillations in continuous culture of Lactobacillus plantarum.

Lactobacillus plantarum exhibited long-period damped oscillations when grown aerobically with glucose as the rate-limiting substrate. Hydrogen peroxide accumulated in the cultures and its concentration also exhibited damped oscillations. It is suggested that inhibition of growth by hydrogen peroxide is involved in the production of the damped oscillations of microbiol population density.


A morphological mutant of Paracoccidioides brasiliensis strain IVIC Pb9. Isolation and wall characterization.

A morphological mutant of Paracoccidioides brasiliensis strain IVIC Pb9 was isolated after treatment of the yeast-like (Y) form with nitrosoguanidine. Colonies of the mutant grown at room temperature did not show the whitish cotton-like morphology typical of the mycelial form of the parental strain. Y-cells were much smaller than those produced by the parent and grew forming chains of different sizes. The main chemical difference in the wall of the Y-form was the replacement of the alpha-I,3-glucan, typical of the parental strain, by an amorphous I,3-mannan in the mutant.


Heterokaryosis in Fusarium oxysporum f.sp. lycopersici.

Intra-isolate and inter-isolate heterokaryons were synthesized between auxotrophic mutants of Fusarium crown rot, 'purple variant' and the wilt isolates. This is the first report of intra- and inter-isolate heterokaryons in Fusarium oxysporum f.sp. lycopersici. Conidial ratios determined for several heterokaryons between different mutants of the Fusarium crown rot organism showed that the ratio is constant for each heterokaryon and that the ratio usually is in favour of one of the mutants.


Failure of complex supplementation of minimal cultures to elicit a shift-up response in Pseudomonas putida.

The addition of complex supplements (particularly amino acids) to cultures of Pseudomonas putida growing on a good carbon source did not result in a substantial increase in the growth rate. Amino acids entered the cells within 30 s of addition and reached significant internal pool concentrations. Endogenous amino acid biosynthesis was quickly inhibited (about 75%), with a substantial sparing of the original carbon source. Within 20 min of supplementation significant respiration of added amino acids was detected, yet the ATP pool size did not increase and the bacteria did not grow faster. The RNA content of P. putida growing in complex medium differed from that of enteric bacteria in that, although it varied with growth rate, it was not substantially larger than the RNA content of bacteria grown in a minimal medium with a good carbon and energy source. The rate of RNA accumulation on shift-up remained substantially unchanged on supplementation if the minimal medium had a carbon source producing fast growth, and did not increase for about 30 min if the carbon source was relatively poor. In other respects RNA synthesis was similar to that of the enteric bacteria, being stringently controlled, inhibited by trimethoprim and continuing in the presence of chloramphenicol. It is proposed that growth of P. putida in complex media is limited by the rate of synthesis of stable RNA.


The rate of recombination repair and its relationship to the radiation-induced delay in DNA synthesis in Micrococcus radiodurans.

The measurement of the time at which normal colony-forming ability returns in irradiated cultures of Micrococcus radiodurans tsI held at 30 degrees C can be used to estimate the time of completion of recombination repair. By comparing the times to complete such repair in populations given increasing radiation doses it is possible to calculate the rate of recombination repair. The rate was independent of the radiation dose; recombination could repair in one minute the damage caused either by 1-2 krad gamma radiation or 4 X 10(-6) J mm-2 u.v. radiation. The time taken for the normal rate of DNA synthesis to return in irradiated M. radiodurans tsI was measured under conditions identical to those used to measure recombination repair. The delay in DNA synthesis was 1-0 min per 1-2 krad gamma radiation and 1-0 min per 5-6 X 10(-6) J mm-2 u.v. radiation. The data suggest that the normal rate of DNA synthesis resumes immediately after the completion of recombination repair of gamma-induced damage, but before the completion of recombination repair of u.v.-induced damage. It is postulated that cell death at the lethal dose of u.v. radiation is caused by a second round of replication of DNA which is still being repaired by recombination.


A biochemical basis for obligate methylotrophy: properties of a mutant of Pseudomonas AM1 lacking 2-oxoglutarate dehydrogenase.

Pseudomonas AMI is a facultative methylotroph which grows on a wide range of carbon compounds. A mutant of Pseudomonas AMI (ICT4I) grew only on C1 compounds and is thus an artificial obligate methylotroph. Measurements of activities of the components of the 2-oxoglutarate dehydrogenase complex suggest that the E2 component (dihydrolipoamide transsuccinylase) is not functional. All other tricarboxylic acid cycle enzymes were present with activities comparable to those in wild-type Pseudomonas AMI and cytochrome levels were unchanged in the mutant. Suspensions of the mutant oxidized pyruvate, lactate, beta-hydroxybutyrate, acetoacetate and 2-oxoglutarate at very low rates. By contrast, C1 compounds were oxidized at the same rate as in wild-type bacteria. Two revertants of ICT4I which regained 2-oxyoglutarate dehydrogenase activity also regained the ability to oxidize and grow on the same substrates as wild-type bacteria. It is concluded that lack of 2-oxoglutarate dehydrogenase may well be the basis of obligate methylotrophy in some bacteria.


Differentiation of Micrococcus luteus and Micrococcus varians on the basis of catalase isoenzymes.

Crude extracts prepared from four Micrococcus varians strains, 11 M. luteus strains and four laboratory isolates subsequently classified with M. luteus were assayed for catalase activity following electrophoresis on polyacrylamide gels. The enzyme patterns produced from the M. varians strains exhibited three catalase isoenzymes which were distinguished into two types of patterns depending upon the location of the major band. The extracts from all the M. luteus strains produced the same pattern, composed of two catalase isoenzymes of similar electrophoretic mobility. For both species the isoenzyme patterns agreed with the differentiation based on biochemical properties. The catalase activity activity staining method was shown to be a restricted yet reliable assay in the intrageneric but not intraspecies differentiation of yellow-pigmented micrococci.


Differentiation of Claviceps purpurea in axenic culture.

The growth form of a strain of Claviceps purpurea in axenic culture has been controlled by the amino nitrogen source. Within the pairs asparagine/aspartic acid or glutamine/glutamic acid the amide promoted sphacelial growth of the colony whereas the acid supported differentiation of plectenchymatic sclerotial tissue and synthesis of ergot alkaloids. Sclerotial colonies showed purple pigmentation. The mycelium had a greater lipid content, rich in ricinoleic acid, and sporulation was much less than in sphacelial colonies. Changes in the relative distribution of amino acids between the free and peptidyl components of the cells was most marked with respect to lysine; growth on asparagine resulted in more than half remaining free, whereas less than 10% remained free on aspartic acid. Lysine supplied exogenously as a nitrogen source did not promote sclerotial differentiation. Frequent transfers to fresh medium of colonies grown on dialysis membrane accentuated the extent of sphacelial or sclerotial growth; four transfers during an 18-day growth period yielded mycelia with an alkaloid content (0-4%, w/w) similar to that of parasitic ergot sclerotia. Asparagine and glutamine were taken up more rapidly from liquid media than their corresponding acids, but each acid exerted a dominant effect over the amide, in a mixture providing equivalent nitrogen, resulting in differentiation from sphacelial to sclerotial growth analogous to that occurring during parasitism. The apparently greater (w/w) proportion of total amino acids in sphacelial mycelia than in sclerotial mycelia mainly reflected the lower lipid content of these tissues, but this factor was insufficient to account for the persistence of a significant proportion of the total lysine amongst the free amino acids. The promotion of sclerotial growth by aspartic and glutamic acids was not confined solely to the experimental strain of the fungus. Although some isolates failed to differentiate into plectenchymatic mycelia on these nitrogen sources, the extent of their sphacelial growth, as indicated by the degree of sporulation, was always much reduced with respect to that promoted by asparagine.


Changes in spores of Clostridium bifermentans caused by treatment with hydrogen peroxide and cations.

Spores of Clostridium bifermentans were treated with hydrogen peroxide until their peripheries had lost refractility. The centres of such spores only retained refractility at acid pH. Adding monovalent cations or increasing the pH caused the treated spores to lose their remaining refractility and decreased the turbidity of spore suspensions. Divalent cations prevented or reversed this loss of central refractility and decreased the fall in turbidity. Calcium ions also prevented but did not reverse the loss of central refractility which occurred on drying or applying pressure. Electron micrographs of spores treated with hydrogen peroxide showed that the cortex was depleted or absent and that the loss of central refractility was accompanied by protoplast swelling. It is suggested that divalent cations make spores resistant to drying and pressure by cross-linking negatively charged groups within the protoplast, and that together with hydrogen ions they neutralize the negatively charged groups, thus preventing the swelling of the protoplast, loss of refractility and fall in extinction which occur when divalent cations are replaced by monovalent cations.


A taxonomic study of the Aeromonas hydrophila-Aeromonas punctata group.

A total of 203 characters has been determined for 68 strains of Aeromonas belonging to the Aeromonas hydrophila-A. punctata group. The results have been subjected to computer analysis using the coefficient of Jaccard-Sneath and the strains clustered by the method of aggregation according to the variance. The 68 strains can be divided into two well-segregated classes on the basis of 59 variable characters, of which seven are of diagnostic value. The two classes are considered as two separate species. The first one (42 strains) is assigned to the type species of the genus, A. hydrophila, and it appears that the species name, A. punctata, is an illegitimate synonym for A. hydrophila. The second (26 strains) constitutes a new species for which the name A. sobria sp. nov. is proposed. The type strain of this new species has been deposited under the reference CIP7433 (our strain 208).


Synchronous growth of Rhodopseudomonas palustris from the swarmer phase.

Rhodopseudomonas palustris was chosen as a model organism for studying bacterial differentiation. Synchronous populations selected by sucrose gradient centrifugation yielded more than 95% swarmer cells. The appearance and disappearance of cell morphological groupings and the doubling of cell numbers in cultures of such swarmer populations were very well defined. Cells were only motile for the first half of the division cycle, but motility was regained before division. Development gave rise to a distinct and characteristic pattern of extinction increase and particle volume distribution. The development of swarmers into mother cells and the dimorphic division of R. palustris are discussed as simple examples of differentiation.


Regulatory properties of an inducible aliphatic amidase in a thermophilic bacillus.

A thermophilic bacillus growing on acetamide as both carbon and nitrogen sources produces an inducible amidase. This amidase hydrolysed the following amides in decreasing order or activity, in comparison with acetamide (1.00): propionamide (0.97), fluoroacetamide (0.84), formamide (0.35) and glycinamide (0.12). Cyanoacetamide, dimethylacetamide, dimethylformamide and urea also induced the synthesis of the amidase, but were not substrates of the enzyme. Studies with protoplasts suggest that the amidase is located in the cytoplasm. Glucose strongly inhibited amidase synthesis; and limiting nitrogen did not release this inhibition. Urea strongly inhibited amidase activity in a competitive manner; but the inhibition caused by iodoacetamide and cyanoacetamide was non-competitive. Both thioacetamide and thiourea were effective inhibitors of enzyme induction. Bacteria grown on a succinate-minimal medium exhibited a lag in amidase synthesis, which could be eliminated by decreasing the concentration of succinate. Acetate- or pyruvate-grown cultures behaved similarly, while those grown on alanine or glutamate exhibited no lag in enzyme induction. In the mutant strain E21, repression of amidase synthesis by glucose was much less evident and no lag for induction was apparent with any of the other carbon sources mentioned.


Chloramphenicol acetylation in Streptomyces.

Twenty-one strains of actinomycetes were screened for the presence of chloramphenicol acetyltransferase, the enzyme responsible for chloramphenicol resistance in many species of bacteria. Only five strains, belonging to three species, yielded mycelial lysates which catalysed the formation of chloramphenicol acetates in the presence of acetyl-coenzyme A: Streptomyces coelicolor Müller, S. acrimycini, and S. griseus. A mutant of S. acrimycini selected for an increase in resistance to chloramphenicol had a higher specific activity for chloramphenicol acetyltransferase than that found in the parental strain; the enzyme was not inducible in the mutant, the parental strain, or any other strain tested. Chloramphenicol was not acetylated by lysates of a strain of S. venezuelae, the organism known to produce it.


Highly specific bacteriophage-associated polysaccharide hydrolases for Klebsiella aerogenes type 8.

Two phage-bound polysaccharide hydrolases specific for Klebsiella aerogenes type 8 exopolysaccharides were isolated. Each enzyme was specific for the polysaccharide produced by the host strain. One enzyme hydrolysed a pyruvylated and acetylated polymer, while the other only acted on the substrate lacking these substituents. Both enzymes were endogalactosidases releasing tetrasaccharides from their substrates which were only hydrolysed to a limited extent.


Adenine nucleotide pool and energy charge during growth of a tyrothricin-producing strain of Bacillus brevis.

The adenine nucleotide levels and derived energy charge value of a tyrothricin-producing strain of Bacillus brevis under aerobic conditions were in good agreement with published values for other bacteria. When growing cultures of B. brevis underwent a transition from aerobic to anaerobic conditions, cyclic variations in the level of adenine nucleotides were observed and the energy charge value oxcillated between 0.87 and 0.70. The significance of these changes is considered in relation to antibiotic production as a possible regulatory mechanism in energy metabolism. It is concluded that tyrothricin is not directly involved in the observed changes in energy charge value.


Preparation and characterization of influenza virus cores.

Lipid-free influenza virus cores have been obtained by a three step procedure consisting of (a) treatment with proteolytic enzyme, (b) fixation with formaldehyde and (c) delipidization with saponin or deoxycholate. Several reagents proved efficient in removing the virus lipids as judged by morphological features and increased buoyant density, but only cores prepared by means of sodium deoxycholate have been characterized closely. Ultrathin sections revealed round bodies (about 65 nm in diam.) delineated by a single dense track and with an internal structure very similar to that of the complete virus particles. They contained both the nucleoprotein and the M-protein and no lipids. It is proposed to call the limiting structure which appears (3 to 4 nm thick in ultrathin sections) the core shell.


Variants of the HR strain of Sindbis virus lethal for mice.

We have selected two similar variants of Sindbis HR virus which are lethal for mice. Consecutive brain to brain passage series were conducted in suckling and weanling mice. Specific anti-Sindbis HR neutralization tests and protection tests demonstrate that these viruses are derived from the parent Sindbis HR.


A genetic approach to studies on the synthesis of the complementary RNA's of fowl plague virus.

The rate of incorporation of 5-fluorouracil into complementary strands of replicating RNA of fowl plague virus (FPV) has been studied. The efficiency of incorporation was estimated by determination of the reversion frequency in s-mutants with known types of base transitions in the RNA of the virus particle. It was established that maximum incorporation of 5-fluorouracil into progeny virus particle RNA took place between 2 and 4 h after infection. The maximum incorporation of the mutagen into complementary RNA (plus strands) occurred when the cells were exposed to 5-fluorouracil from 1 to 2 h after infection.


Defective-interfering particles of Semliki Forest Virus: structural differences between standard virus and defective-interfering particles.

Serial passaging of Semlike Forest virus in BHK cells at a constant input multiplicity of 50 p.f.u./cell resulted in a 4 log10 drop in yield of infectious virus by passage 9. An interference analysis showed that this drop was due to the presence of defective-interfering (DI) particles. Attempts were made to separate the DI particles from standard virus by equilibrium and velocity centrifugation. Only equilbrium centrifugation on CsCl resolved the DI particles (identified by interference analyses) from standard virus. The buoyant density of the DI particles (1.23 g/ml) was higher than that of standard virus (p = 1-20 g/ml). No difference was observed between the structural porteins of standard virus and DI particles. Analysis of the RNA of standard virus and DI particles showed that whereas standard virus contained only 42S RNA (mol. wt. approx. 4-2 X 10(6), DI particles contained two small pieces of RNA of mol. wt. 0.81 and 0-75 X 10(6) respectively. Infectivity assays showed that these low mol. wt. species were not only non-infectious but also interfered with the infectivity of 42S RNA from standard virus. Nucleocapsids derived from purified DI particles had a buoyant density 0-02 g/ml greater than the nucleocapsids from standard virus. Analysis of the RNA from DI nucleocapsids showed it to be entirely of the low mol. wt. class. To account therefore for the density difference not only between DI particles and standard virus but also between their respective nucleocapsids we propose that each SFV DI particle contains several molecules of the low mol. wt. RNA species.


Defective-interfering particles of Semliki Forest virus: intracellular events during interference.

Purified defective-interfering (DI) particles of Semliki Forest virus are unable to carry out any of the steps in virus multiplication except uncoating. Cells co-infected with DI particles and standard virus contain several virus-specified RNA species (DI particle-specific species) absent from cells infected with standard virus alone. Moreover, synthesis of all the virus-specified components distinctive of standard virus-infected cells is reduced. The DI particle-specific RNA species comprise two poly A-containing single-stranded RNAs (DIss1 and DIss2), identical to those found in purified DI particles, two double-stranded RNA'S (RFs) and a new size class of replicative intermediate (RI). Hybridization experiments showed that the nucleotide sequences of DIss1 and DIss2 (i) are present in the 42S genome of standard virus but absent from the 26S RNA- the RNA from standard virus-infected cells which encodes the structural proteins of the virion (Clegg & Kennedy, 1975 a) and (ii) are complementary to the negative strands of the DI paritcle-specific RFs and RI. Oligonucleotide fingerprinting revealed extensive nucleotide sequence homology between DIssI and DIss2. Analysis of the mRNA complement of standard virus-infected, co-infected and uninfected cells strongly indicated that neither DIss1 nor DIss2 can serve as a functional messenger RNA. From these studies we propose a mechanism for the multiplication of and interference by DI particles of Semliki Forest virus.


[Genetic counseling in retinoblastoma].

The author reviews the literature about the inheritance of retinoblastoma and notes an increase of both the frequency of the affection and the chance of survival. He then estimates the genetic risks for the descendency in all cases of sporadic and familial retinoblastoma.


[Polycystic kidney disease of the newborn in two different sibships].

The two only children in two different sibships died soon after birth from polycystic kidney disease. Autopsy disclosed hepatic lesions. The modes of transmission of this disease are discussed.


The importance of determining the mode of inheritance for the estimation of recurrence risks.

Recurrence risks for the generalised single locus model and for the multifactorial model have been derived and compared. First the areas of overlap for the two models were determined and sets of parameters chosen to represent these overlap areas. Certain sets of parameters for the single locus model give recurrence risks in sibships similar to these for multifactorial inheritance. Other sets (representing very low penetrant dominant genes) give markedly lower risks. Similar results hold for more complex family histories. Empiric risks for families with two or more affected individuals are needed so as to indicate the trend of the increase in risk which could then be extrapolated to other families and be used in genetic counseling.


The development of trait inference.

This study charted the increase with age in trait inference and examined the accompanying organizational processes. The Ss, eight males and eight females at each grade level from kindergarten through sixth, were read descriptions of other children. These served as the basis for "spontaneous" and "suggested" inferences which they were then asked to justify. Trait inference appeared as early as kindergarten and increased in frequency up to sixth grade. This increase was explained as evidence of a greater capacity for hierarchical organization. The justifications were classified into five reasoning categories which were interpreted in terms of the social psychological literature and Piaget's (16, 17) "mother structures."


The psychological effects of vasectomy for American men.

Evidence concerning the psychological effects of vasectomy for American men was reviewed. Surveys of postoperative sexual behavior, satisfaction, and/or happiness suggest that the effects of vasectomy are generally positive. Data from studies employing clinical interviews and/or psychological tests, however, support a very different conclusion. These investigations which are generally superior in methodology and measurement techniques to the survey studies indicate that (a) although men in general verbally express satisfaction with vasectomy, many men are probably describing feelings which have been distorted as part of an attempt to cope with their private concerns about the consequences of the operation; and (b) many men experience some difficulty in adjusting to the psychological consequences of vasectomy. Implications for future research are discussed.


Aggressive behavior as a function of age and sex.

The present experiment investigated age and sex differences in aggressive behavior. With the use of an apparatus which delivered differentially noxious noise bursts, 40 male and female Ss of preschool and adolescent age aggressed against a male or female peer. Results indicated that aggression by and toward females was relatively stable over age, while aggression by males toward other males increased markedly (p less than .05). The implication of findings for reinforcement explanations of sex differences in aggression are discussed.


Factors affecting accuracy of perception on a task requiring the ability to identify viewpoints.

A study was undertaken to determine the relative contribution of age, sex, and three stimulus features (board shape, block arrangement, and block shape) to perceptual accuracy on 39 board/block adaptations of Piaget's three-mountain task. The sample consisted of 830 children (420 1st graders and 410 5th graders) and 130 college students. Stimulus features of the board/block task accounted for between 22% and 26% of the explained variability among accuracy scores; however, interactions of other factors with age were nonsignificant. When data from college students were combined with children, a curvilinear developmental relationship between age and perceptual accuracy was obtained. The board/block task has promise as an instrument for longitudinal studies.


An exploratory study of the interaction of cognitive complexity, dogmatism, and repression-sensitization among college students.

Two hundred nineteen male and female college students returned questionnaire measures relating to cognitive complexity, dogmatism, and repression-sensitization. Analyses revealed very complex interactions among the variables. Highly dogmatic repressors were low in cognitive complexity, and open- minded sensitizers were high in cognitive complexity. Ss exhibiting other combinations of dogmatism and repression-sensitization (e.g., highly dogmatic sensitizers, open-minded repressors) were moderate in cognitive complexity. Many of the conclusions about the behavioral correlates of cognitive complexity, dogmatism, and repression-sensitization may be confounded if these variables are not conjointly assessed.


Comparison of aggression and incongruity as factors in children's judgments of humor.

It was hypothesized that both aggression and incongruity are variables that will positively influence preschool children's judgments of humorous incidents. Past research has shown the influence of incongruity on humor only for school-age children, and--with the exception of studies of children's television viewing--the allegedly "antisocial" variable of aggression has been ignored. Two hundred and thirty boys and girls from ages three to eight each made six paired comparison judgments as to which of two brief incidents was funnier. The incidents were produced by the E manipulating either one or two hand puppets with or without accompanying dialogue. At all ages children significantly preferred aggressive and incongruous incidents to neutral incidents. When aggressive and incongruous nonverbal incidents were paired, there was no significant preference. Two major conclusions were reached: (a) Though neglected in the developmental theory of humor, aggression is an early occurring and potent factor in children's humor; (b) The clear-cut results obtained from preschoolers argue for the usefulness of cognitive choice as against such observational measures as smiling and laughing.


Egocentric error and the construct of egocentrism.

It was hypothesized that perception errors on a task requiring Ss to take different viewpoints could be explained in terms of response bias. Four hundred ten first graders, 421 fifth graders, and 260 undergradutaes' error patterns on 39 board/block adaptations of Piaget's three-mountain task were examined with respect to their front, opposite, and reversed choices of camera position. Front choices or egocentric errors were found, overall, to be independent of grade level. Results from this analysis were consistent with the response bias hypothesis: clearly, making an egocentric error is different from behaving in an egocentric manner.