Dinoflagellate

The dinoflagellates (Greek δῖνος "dinos" "whirling" and Latin "flagellum" "whip, scourge") are single-celled eukaryotes constituting the phylum Dinoflagellata. Usually considered algae, dinoflagellates are mostly marine plankton, but they also are common in freshwater habitats. Their populations are distributed depending on sea surface temperature, salinity, or depth. Many dinoflagellates are known to be photosynthetic, but a large fraction of these are in fact mixotrophic, combining photosynthesis with ingestion of prey (phagotrophy and myzocytosis).
In terms of number of species, dinoflagellates are one of the largest groups of marine eukaryotes, although this group is substantially smaller than diatoms. Some species are endosymbionts of marine animals and play an important part in the biology of coral reefs. Other dinoflagellates are unpigmented predators on other protozoa, and a few forms are parasitic (for example, "Oodinium" and "Pfiesteria"). Some dinoflagellates produce resting stages, called dinoflagellate cysts or dinocysts, as part of their lifecycles, and is known from 84 of the 350 described freshwater species, and from a little more than 10% of the known marine species. Dinoflagellates are alveolates possessing two flagella, the ancestral condition of bikonts.
About 1,555 species of free-living marine dinoflagellates are currently described. Another estimate suggests about 2,000 living species, of which more than 1,700 are marine (free-living, as well as benthic) and about 220 are from fresh water. The latest estimates suggest a total of 2,294 living dinoflagellate species, which includes marine, freshwater, and parasitic dinoflagellates.
A rapid accumulation of certain dinoflagellates can result in a visible coloration of the water, colloquially known as red tide (a harmful algal bloom), which can cause shellfish poisoning if humans eat contaminated shellfish. Some dinoflagellates also exhibit bioluminescence—primarily emitting blue-green light. Thus, some parts of the Indian Ocean light up at night giving blue-green light.
History.
In 1753, the first modern dinoflagellates were described by Henry Baker as "Animalcules which cause the Sparkling Light in Sea Water", and named by Otto Friedrich Müller in 1773. The term derives from the Greek word δῖνος ("dinos"), meaning whirling, and Latin "flagellum", a diminutive term for a whip or scourge.
In the 1830s, the German microscopist Christian Gottfried Ehrenberg examined many water and plankton samples and proposed several dinoflagellate genera that are still used today including "Peridinium, Prorocentrum", and "Dinophysis".
These same dinoflagellates were first defined by Otto Bütschli in 1885 as the flagellate order Dinoflagellida. Botanists treated them as a division of algae, named Pyrrophyta or Pyrrhophyta ("fire algae"; Greek "pyrr(h)os", fire) after the bioluminescent forms, or Dinophyta. At various times, the cryptomonads, ebriids, and ellobiopsids have been included here, but only the last are now considered close relatives. Dinoflagellates have a known ability to transform from noncyst to cyst-forming strategies, which makes recreating their evolutionary history extremely difficult.
Morphology.
Dinoflagellates are unicellular and possess two dissimilar flagella arising from the ventral cell side (dinokont flagellation). They have a ribbon-like transverse flagellum with multiple waves that beats to the cell's left, and a more conventional one, the longitudinal flagellum, that beats posteriorly. The transverse flagellum is a wavy ribbon in which only the outer edge undulates from base to tip, due to the action of the axoneme which runs along it. The axonemal edge has simple hairs that can be of varying lengths. The flagellar movement produces forward propulsion and also a turning force. The longitudinal flagellum is relatively conventional in appearance, with few or no hairs. It beats with only one or two periods to its wave. The flagella lie in surface grooves: the transverse one in the cingulum and the longitudinal one in the sulcus, although its distal portion projects freely behind the cell. In dinoflagellate species with desmokont flagellation (e.g., "Prorocentrum"), the two flagella are differentiated as in dinokonts, but they are not associated with grooves.
Dinoflagellates have a complex cell covering called an amphiesma or cortex, composed of a series of membranes, flattened vesicles called alveolae (= amphiesmal vesicles) and related structures. In armoured dinoflagellates, these support overlapping cellulose plates to create a sort of armor called the theca or lorica, as opposed to athecate dinoflagellates. These occur in various shapes and arrangements, depending on the species and sometimes on the stage of the dinoflagellate. Conventionally, the term tabulation has been used to refer to this arrangement of thecal plates. The plate configuration can be denoted with the plate formula or tabulation formula. Fibrous extrusomes are also found in many forms. Together with various other structural and genetic details, this organization indicates a close relationship between the dinoflagellates, the Apicomplexa, and ciliates, collectively referred to as the alveolates.
Dinoflagellate tabulations can be grouped into six "tabulation types": gymnodinoid, suessoid, gonyaulacoid–peridinioid, nannoceratopsioid, dinophysioid, and prorocentroid.
The chloroplasts in most photosynthetic dinoflagellates are bound by three membranes, suggesting they were probably derived from some ingested algae. Most photosynthetic species contain chlorophylls "a" and c2, the carotenoid beta-carotene, and a group of xanthophylls that appears to be unique to dinoflagellates, typically peridinin, dinoxanthin, and diadinoxanthin. These pigments give many dinoflagellates their typical golden brown color. However, the dinoflagellates "Karenia brevis, Karenia mikimotoi," and "Karlodinium micrum" have acquired other pigments through endosymbiosis, including fucoxanthin.
This suggests their chloroplasts were incorporated by several endosymbiotic events involving already colored or secondarily colorless forms. The discovery of plastids in the Apicomplexa has led some to suggest they were inherited from an ancestor common to the two groups, but none of the more basal lines has them.
All the same, the dinoflagellate cell consists of the more common organelles such as rough and smooth endoplasmic reticulum, Golgi apparatus, mitochondria, lipid and starch grains, and food vacuoles. Some have even been found with a light-sensitive organelle, the eyespot or stigma, or a larger nucleus containing a prominent nucleolus. The dinoflagellate "Erythropsidium" has the smallest known eye.
Some athecate species have an internal skeleton consisting of two star-like siliceous elements that has an unknown function, and can be found as microfossils. Tappan gave a survey of dinoflagellates with internal skeletons. This included the first detailed description of the pentasters in "Actiniscus pentasterias", based on scanning electron microscopy. They are placed within the order Gymnodiniales, suborder Actiniscineae.
Theca structure and formation.
The formation of thecal plates has been studied in detail through ultrastructural studies.
The dinoflagellate nucleus: dinokaryon.
'Core dinoflagellates' (dinokaryotes) have a peculiar form of nucleus, called a dinokaryon, in which the chromosomes are attached to the nuclear membrane. These carry reduced number of histones. In place of histones, dinoflagellate nuclei contain a novel, dominant family of nuclear proteins that appear to be of viral origin, thus are called Dinoflagellate viral nucleoproteins (DVNPs) which are highly basic, bind DNA with similar affinity to histones, and occur in multiple posttranslationally modified forms. Dinoflagellate nuclei remain condensed throughout interphase rather than just during mitosis, which is closed and involves a uniquely extranuclear mitotic spindle. This sort of nucleus was once considered to be an intermediate between the nucleoid region of prokaryotes and the true nuclei of eukaryotes, so were termed mesokaryotic, but now are considered derived rather than primitive traits (i.e. ancestors of dinoflagellates had typical eukaryotic nuclei). In addition to dinokaryotes, DVNPs can be found in a group of basal dinoflagellates (known as Marine Alveolates, "MALVs") that branch as sister to dinokaryotes (Syndiniales).
Classification.
Dinoflagellates are protists which have been classified using both the International Code of Botanical Nomenclature (ICBN, now renamed as ICN) and the International Code of Zoological Nomenclature (ICZN). About half of living dinoflagellate species are autotrophs possessing chloroplasts and half are nonphotosynthesising heterotrophs.
The peridinin dinoflagellates, named after their peridinin plastids, appears to be ancestral for the dinoflagellate lineage. Almost half of all known species have chloroplasts, which are either the original peridinin plastids or new plastids acquired from other lineages of unicellular algae through endosymbiosis. The remaining species have lost their photosynthetic abilities and have adapted to a heterotrophic, parasitic or kleptoplastic lifestyle.
Most (but not all) dinoflagellates have a dinokaryon, described below (see: Life cycle, below). Dinoflagellates with a dinokaryon are classified under Dinokaryota, while dinoflagellates without a dinokaryon are classified under Syndiniales.
Although classified as eukaryotes, the dinoflagellate nuclei are not characteristically eukaryotic, as some of them lack histones and nucleosomes, and maintain continually condensed chromosomes during mitosis. The dinoflagellate nucleus was termed ‘mesokaryotic’ by Dodge (1966), due to its possession of intermediate characteristics between the coiled DNA areas of prokaryotic bacteria and the well-defined eukaryotic nucleus. This group, however, does contain typically eukaryotic organelles, such as Golgi bodies, mitochondria, and chloroplasts.
Jakob Schiller (1931–1937) provided a description of all the species, both marine and freshwater, known at that time. Later, Alain Sournia (1973, 1978, 1982, 1990, 1993) listed the new taxonomic entries published after Schiller (1931–1937). Sournia (1986) gave descriptions and illustrations of the marine genera of dinoflagellates, excluding information at the species level. The latest index is written by Gómez.
Identification.
English-language taxonomic monographs covering large numbers of species are published for the Gulf of Mexico, the Indian Ocean, the British Isles, the Mediterranean and the North Sea.
The main source for identification of freshwater dinoflagellates is the "Süsswasser Flora".
Calcofluor-white can be used to stain thecal plates in armoured dinoflagellates.
Ecology and physiology.
Habitats.
Dinoflagellates can occur in all aquatic environments: marine, brackish, and fresh water, including in snow or ice. They are also common in benthic environments and sea ice.
Endosymbionts.
All Zooxanthellae are dinoflagellates and most of them are members within Symbiodiniaceae (e.g. the genus "Symbiodinium"). The association between "Symbiodinium" and reef-building corals is widely known. However, endosymbiontic Zooxanthellae inhabit a great number of other invertebrates and protists, for example many sea anemones, jellyfish, nudibranchs, the giant clam "Tridacna", and several species of radiolarians and foraminiferans. Many extant dinoflagellates are parasites (here defined as organisms that eat their prey from the inside, i.e. endoparasites, or that remain attached to their prey for longer periods of time, i.e. ectoparasites). They can parasitize animal or protist hosts. "Protoodinium, Crepidoodinium, Piscinoodinium", and "Blastodinium" retain their plastids while feeding on their zooplanktonic or fish hosts. In most parasitic dinoflagellates, the infective stage resembles a typical motile dinoflagellate cell.
Nutritional strategies.
Three nutritional strategies are seen in dinoflagellates: phototrophy, mixotrophy, and heterotrophy. Phototrophs can be photoautotrophs or auxotrophs. Mixotrophic dinoflagellates are photosynthetically active, but are also heterotrophic. Facultative mixotrophs, in which autotrophy or heterotrophy is sufficient for nutrition, are classified as amphitrophic. If both forms are required, the organisms are mixotrophic "sensu stricto". Some free-living dinoflagellates do not have chloroplasts, but host a phototrophic endosymbiont. A few dinoflagellates may use alien chloroplasts (cleptochloroplasts), obtained from food (kleptoplasty). Some dinoflagellates may feed on other organisms as predators or parasites.
Food inclusions contain bacteria, bluegreen algae, small dinoflagellates, diatoms, ciliates, and other dinoflagellates.
Mechanisms of capture and ingestion in dinoflagellates are quite diverse. Several dinoflagellates, both thecate (e.g. "Ceratium hirundinella", "Peridinium globulus") and nonthecate (e.g. "Oxyrrhis marina", "Gymnodinium" sp. and "Kofoidinium" spp.), draw prey to the sulcal region of the cell (either via water currents set up by the flagella or via pseudopodial extensions) and ingest the prey through the sulcus. In several "Protoperidinium" spp., e.g. "P. conicum", a large feeding veil — a pseudopod called the pallium — is extruded to capture prey which is subsequently digested extracellularly (= pallium-feeding). "Oblea", "Zygabikodinium", and "Diplopsalis" are the only other dinoflagellate genera known to use this particular feeding mechanism.
"Katodinium (Gymnodinium) fungiforme", commonly found as a contaminant in algal or ciliate cultures, feeds by attaching to its prey and ingesting prey cytoplasm through an extensible peduncle. Two related species, polykrikos kofoidii and neatodinium, shoots out a harpoon-like organelle to capture prey. The feeding mechanisms of the oceanic dinoflagellates remain unknown, although pseudopodial extensions were observed in "Podolampas bipes".
Blooms.
Dinoflagellate blooms are generally unpredictable, short, with low species diversity, and with little species succession. The low species diversity can be due to multiple factors. One way a lack of diversity may occur in a bloom is through a reduction in predation and a decreased competition. The first may be achieved by having predators reject the dinoflagellate, by, for example, decreasing the amount of food it can eat. This additionally helps prevent a future increase in predation pressure by cause predators that reject it to lack the energy to breed. A species can then inhibit the growth of its competitors, thus achieving dominance.
Harmful algal blooms.
Dinoflagellates sometimes bloom in concentrations of more than a million cells per millilitre. Under such circumstances, they can produce toxins (generally called dinotoxins) in quantities capable of killing fish and accumulating in filter feeders such as shellfish, which in turn may be passed on to people who eat them. This phenomenon is called a red tide, from the color the bloom imparts to the water. Some colorless dinoflagellates may also form toxic blooms, such as "Pfiesteria". Some dinoflagellate blooms are not dangerous. Bluish flickers visible in ocean water at night often come from blooms of bioluminescent dinoflagellates, which emit short flashes of light when disturbed.
The same red tide mentioned above is more specifically produced when dinoflagellates are able to reproduce rapidly and copiously on account of the abundant nutrients in the water. Although the resulting red waves are an unusual sight, they contain toxins that not only affect all marine life in the ocean, but the people who consume them, as well. A specific carrier is shellfish. This can introduce both nonfatal and fatal illnesses. One such poison is saxitoxin, a powerful paralytic neurotoxin. Human inputs of phosphate further encourage these red tides, so strong interest exists in learning more about dinoflagellates, from both medical and economic perspectives. Dinoflagellates are known to be particularly capable of scavenging dissolved organic phosphorus for P-nutrient, several HAS species have been found to be highly versatile and mechanistically diversified in utilizing different types of DOPs. The ecology of harmful algal blooms is extensively studied.
Bioluminescence.
At night, water can have an appearance of sparkling light due to the bioluminescence of dinoflagellates. More than 18 genera of dinoflagellates are bioluminescent, and the majority of them emit a blue-green light. These species contain scintillons, individual cytoplasmic bodies (about 0.5 µm in diameter) distributed mainly in the cortical region of the cell, outpockets of the main cell vacuole. They contain dinoflagellate luciferase, the main enzyme involved in dinoflagellate bioluminescence, and luciferin, a chlorophyll-derived tetrapyrrole ring that acts as the substrate to the light-producing reaction. The luminescence occurs as a brief (0.1 sec) blue flash (max 476 nm) when stimulated, usually by mechanical disturbance. Therefore, when mechanically stimulated—by boat, swimming, or waves, for example—a blue sparkling light can be seen emanating from the sea surface.
Dinoflagellate bioluminescence is controlled by a circadian clock and only occurs at night. Luminescent and nonluminescent strains can occur in the same species. The number of scintillons is higher during night than during day, and breaks down during the end of the night, at the time of maximal bioluminescence.
The luciferin-luciferase reaction responsible for the bioluminescence is pH sensitive. When the pH drops, luciferase changes its shape, allowing luciferin, more specifically tetrapyrrole, to bind. Dinoflagellates can use bioluminescence as a defense mechanism. They can startle their predators by their flashing light or they can ward off potential predators by an indirect effect such as the "burglar alarm". The bioluminescence attracts attention to the dinoflagellate and its attacker, making the predator more vulnerable to predation from higher trophic levels.
Bioluminescent dinoflagellate ecosystem bays are among the rarest and most fragile, with the most famous ones being the Bioluminescent Bay in La Parguera, Lajas, Puerto Rico; Mosquito Bay in Vieques, Puerto Rico; and Las Cabezas de San Juan Reserva Natural Fajardo, Puerto Rico. Also, a bioluminescent lagoon is near Montego Bay, Jamaica, and bioluminescent harbors surround Castine, Maine. Within the United States, Central Florida is home to the Indian River Lagoon which is abundant with dinoflagellates in the summer and bioluminescent ctenophore in the winter.
Lipid and sterol production.
Dinoflagellates produce characteristic lipids and sterols. One of these sterols is typical of dinoflagellates and is called dinosterol.
Transport.
Dinoflagellate theca can sink rapidly to the seafloor in marine snow.
Life cycle.
Dinoflagellates have a haplontic life cycle, with the possible exception of "Noctiluca" and its relatives.
The life cycle usually involves asexual reproduction by means of mitosis, either through desmoschisis or eleuteroschisis. More complex life cycles occur, more particularly with parasitic dinoflagellates. Sexual reproduction also occurs, though this mode of reproduction is only known in a small percentage of dinoflagellates. This takes place by fusion of two individuals to form a zygote, which may remain mobile in typical dinoflagellate fashion and is then called a planozygote. This zygote may later form a resting stage or hypnozygote, which is called a dinoflagellate cyst or dinocyst. After (or before) germination of the cyst, the hatchling undergoes meiosis to produce new haploid cells. Dinoflagellates appear to be capable of carrying out several DNA repair processes that can deal with different types of DNA damage
Dinoflagellate cysts.
The life cycle of many dinoflagellates includes at least one nonflagellated benthic stage as a cyst). Different types of dinoflagellate cysts are mainly defined based on morphological (number and type of layers in the cell wall) and functional (long- or short-term endurance) differences. These characteristics were initially thought to clearly distinguish pellicle (thin-walled) cysts from resting (double-walled) dinoflagellate cysts. The former were considered short-term (temporal) and the latter long-term (resting) cysts. However, during the last two decades further knowledge has highlighted the great intricacy of dinoflagellate life histories.
More than 10% of the approximately 2000 known marine dinoflagellate species produce cysts as part of their life cycle (see diagram on the right). These benthic phases play an important role in the ecology of the species, as part of a planktonic-benthic link in which the cysts remain in the sediment layer during conditions unfavorable for vegetative growth and, from there, reinoculate the water column when favorable conditions are restored.
Indeed, during dinoflagellate evolution the need to adapt to fluctuating environments and/or to seasonality is thought to have driven the development of this life cycle stage. Most protists form dormant cysts in order to withstand starvation and UV damage. However, there are enormous differences in the main phenotypic, physiological and resistance properties of each dinoflagellate species cysts. Unlike in higher plants most of this variability, for example in dormancy periods, has not been proven yet to be attributed to latitude adaptation or to depend on other life cycle traits. Thus, despite recent advances in the understanding of the life histories of many dinoflagellate species, including the role of cyst stages, many gaps remain in knowledge about their origin and functionality.
Recognition of the capacity of dinoflagellates to encyst dates back to the early 20th century, in biostratigraphic studies of fossil dinoflagellate cysts. Paul Reinsch was the first to identify cysts as the fossilized remains of dinoflagellates. Later, cyst formation from gamete fusion was reported, which led to the conclusion that encystment is associated with sexual reproduction. These observations also gave credence to the idea that microalgal encystment is essentially a process whereby zygotes prepare themselves for a dormant period. Because the resting cysts studied until that time came from sexual processes, dormancy was associated with sexuality, a presumption that was maintained for many years. This attribution was coincident with evolutionary theories about the origin of eukaryotic cell fusion and sexuality, which postulated advantages for species with diploid resting stages, in their ability to withstand nutrient stress and mutational UV radiation through recombinational repair, and for those with haploid vegetative stages, as asexual division doubles the number of cells. Nonetheless, certain environmental conditions may limit the advantages of recombination and sexuality, such that in fungi, for example, complex combinations of haploid and diploid cycles have evolved that include asexual and sexual resting stages.
However, in the general life cycle of cyst-producing dinoflagellates as outlined in the 1960s and 1970s, resting cysts were assumed to be the fate of sexuality, which itself was regarded as a response to stress or unfavorable conditions. Sexuality involves the fusion of haploid gametes from motile planktonic vegetative stages to produce diploid planozygotes that eventually form cysts, or hypnozygotes, whose germination is subject to both endogenous and exogenous controls. Endogenously, a species-specific physiological maturation minimum period (dormancy) is mandatory before germination can occur. Thus, hypnozygotes were also referred to as “resting” or “resistant” cysts, in reference to this physiological trait and their capacity following dormancy to remain viable in the sediments for long periods of time. Exogenously, germination is only possible within a window of favorable environmental conditions.
Yet, with the discovery that planozygotes were also able to divide it became apparent that the complexity of dinoflagellate life cycles was greater than originally thought. Following corroboration of this behavior in several species, the capacity of dinoflagellate sexual phases to restore the vegetative phase, bypassing cyst formation, became well accepted. Further, in 2006 Kremp and Parrow showed the dormant resting cysts of the Baltic cold water dinoflagellates "Scrippsiella hangoei" and "Gymnodinium" sp. were formed by the direct encystment of haploid vegetative cells, i.e., asexually. In addition, for the zygotic cysts of "Pfiesteria piscicida" dormancy was not essential.
Genomics.
One of their most striking features is the large amount of cellular DNA that dinoflagellates contain. Most eukaryotic algae contain on average about 0.54 pg DNA/cell, whereas estimates of dinoflagellate DNA content range from 3–250 pg/cell, corresponding to roughly 3000–215 000 Mb (in comparison, the haploid human genome is 3180 Mb and hexaploid "Triticum" wheat is 16 000 Mb). Polyploidy or polyteny may account for this large cellular DNA content, but earlier studies of DNA reassociation kinetics and recent genome analyses do not support this hypothesis. Rather, this has been attributed, hypothetically, to the rampant retroposition found in dinoflagellate genomes.
In addition to their disproportionately large genomes, dinoflagellate nuclei are unique in their morphology, regulation, and composition. Their DNA is so tightly packed it is still uncertain exactly how many chromosomes they have.
The dinoflagellates share an unusual mitochondrial genome organisation with their relatives, the Apicomplexa. Both groups have very reduced mitochondrial genomes (around 6 kilobases (kb) in the Apicomplexa vs ~16kb for human mitochondria). One species, "Amoebophrya ceratii", has lost its mitochondrial genome completely, yet still has functional mitochondria. The genes on the dinoflagellate genomes have undergone a number of reorganisations, including massive genome amplification and recombination which have resulted in multiple copies of each gene and gene fragments linked in numerous combinations. Loss of the standard stop codons, trans-splicing of mRNAs for the mRNA of cox3, and extensive RNA editing recoding of most genes has occurred. The reasons for this transformation are unknown. In a small group of dinoflagellates, called ‘dinotoms’ (Durinskia
and Kryptoperidinium), the endosymbionts (diatoms) still have mitochondria, making them the only organisms with two evolutionarily distinct mitochondria.
In most of the species, the plastid genome consist of just 14 genes.
The DNA of the plastid in the peridinin-containing dinoflagellates is contained in a series of small circles. Each circle contains one or two polypeptide genes. The genes for these polypeptides are chloroplast-specific because their homologs from other photosynthetic eukaryotes are exclusively encoded in the chloroplast genome. Within each circle is a distinguishable 'core' region. Genes are always in the same orientation with respect to this core region.
In terms of DNA barcoding, ITS sequences can be used to identify species, where a genetic distance of p≥0.04 can be used to delimit species, which has been successfully applied to resolve long-standing taxonomic confusion as in the case of resolving the Alexandrium tamarense complex into five species. A recent study revealed a substantial proportion of dinoflagellate genes encode for unknown functions, and that these genes could be conserved and lineage-specific.
Evolutionary history.
Dinoflagellates are mainly represented as fossils by fossil dinocysts, which have a long geological record with lowest occurrences during the mid-Triassic, whilst geochemical markers suggest a presence to the Early Cambrian.
Some evidence indicates dinosteroids in many Paleozoic and Precambrian rocks might be the product of ancestral dinoflagellates (protodinoflagellates).
Molecular phylogenetics show that dinoflagellates are grouped with ciliates and apicomplexans (=Sporozoa) in a well-supported clade, the alveolates. The closest relatives to dinokaryotic dinoflagellates appear to be apicomplexans, "Perkinsus, Parvilucifera", syndinians, and "Oxyrrhis". Molecular phylogenies are similar to phylogenies based on morphology.
The earliest stages of dinoflagellate evolution appear to be dominated by parasitic lineages, such as perkinsids and syndinians (e.g. "Amoebophrya" and "Hematodinium").
All dinoflagellates contain red algal plastids or remnant (nonphotosynthetic) organelles of red algal origin. The parasitic dinoflagellate "Hematodinium" however lacks a plastid entirely. Some groups that have lost the photosynthetic properties of their original red algae plastids has obtained new photosynthetic plastids (chloroplasts) through so-called serial endosymbiosis, both secondary and tertiary. Like their original plastids, the new chloroplasts in these groups can be traced back to red algae, except from those in the members of the genus Lepidodinium, which possess plastids derived from green algae, possibly Trebouxiophyceae or Ulvophyceae. Lineages with tertiary endosymbiosis are Dinophysis, with plastids from a cryptomonad, the Karenia, Karlodinium, and Takayama, which possess plastids of haptophyte origin, and the Peridiniaceae, Durinskia and Kryptoperidinium, which has plastids derived from diatoms Some species also perform kleptoplasty.
Dinoflagellate evolution has been summarized into five principal organizational types: prorocentroid, dinophysoid, gonyaulacoid, peridinioid, and gymnodinoid.
The transitions of marine species into fresh water have been infrequent events during the diversification of dinoflagellates and in most cases have not occurred recently, possibly as late as the Cretaceous.
Recently, the "living fossil" "Dapsilidinium pastielsii" was found inhabiting the Indo-Pacific Warm Pool, which served as a refugium for thermophilic dinoflagellates.


Mycobacterium pinnipedii

Mycobacterium pinnipedii is a member of the Mycobacterium tuberculosis complex which primarily infects seals. It is a slowly growing Mycobacterium. The species is named after the Pinnipeds, the organisms from which "M. pinnipedii" was first isolated.
In 2014, a genetic study showed that Peruvian human skeleton dating to 1000 CE had been infected with a form of tuberculosis most closely related to "M. pinnipedii", suggesting that seals had served as a vector for transmission of tuberculosis from the Old World to the New.


Journal of Biological Systems

The Journal of Biological Systems was founded in 1993 and is published quarterly by World Scientific.
The journal aims to "promote interdisciplinary approaches in Biology and in Medicine, and the study of biological situations with a variety of tools, including mathematical and general systems methods." It includes articles on complex systems studies, interdisciplinary approaches in biology and medicine, environmental studies, evolutionary biology, medical systems, numerical simulations and computations, and epidemiology.
Abstracting and indexing.
The journal is abstracted and indexed in:


Cribrospora

Cribrospora is a genus of fungus in the order Agaricales. It is "incertae sedis" with respect to familial placement within the order. The genus is monotypic, containing the single species Cribrospora tulostomoides, found in Europe.


Mycobacterium fluoranthenivorans

Mycobacterium fluoranthenivorans is a species of the phylum Actinobacteria (gram-positive bacteria with high guanine and cytosine content, one of the dominant phyla of all bacteria), belonging to the genus "Mycobacterium".
Etymology: fluoranthenivorans, digesting fluoranthene.
Type strain.
First isolated from contaminated soil of a former coal gas plant.
Strain FA4 = DSM 44556 = CIP 108203.


Ishigeaceae


Pacisporaceae

The Pacisporaceae are a family of fungi in the order Diversisporales. The family contains the single genus Pacispora. Species in this genus are widespread in distribution, and form arbuscular mycorrhiza and vesicles in roots.


Knoellia subterranea

Knoellia subterranea is a species of Gram positive, nonmotile, non-sporeforming bacteria. The bacteria are aerobic and mesophilic, and the cells can be irregular rods or coccoid. It was originally isolated from an air sample from cave soil from Reed Flute Cave in Guilin, China. "K. sinensis" was one of the first described species of "Knoellia", being discovered along with the type strain "K. sinensis". The species name refers to its subterranean isolation location.
The optimum growth temperature for "K. subterranea" is 28-37 °C, but cannot grow at 42 °C. The optimum pH is 5.0-9.0.


Blastobotrys

Blastobotrys is a genus of fungi belonging to the family Trichomonascaceae.
The genus has cosmopolitan distribution.
Species.
Species:


Astraeus smithii

Astraeus smithii is a species of false earthstar in the family Diplocystaceae. It was described as new to science in 2013. The specific epithet honors American mycologist Alexander H. Smith. The fungus is found in the central and northern United States, where it grows on the ground at forest edges and open areas.


Brown beech

Brown beech is a common name for several plants and may refer to:


Coagulase

Coagulase is a protein enzyme produced by several microorganisms that enables the conversion of fibrinogen to fibrin. In the laboratory, it is used to distinguish between different types of "Staphylococcus" isolates. Importantly, "S. aureus" is generally coagulase-positive, meaning that a positive coagulase test would indicate the presence of "S. aureus" or any of the other 11 coagulase-positive "Staphylococci". A negative coagulase test would instead show the presence of coagulase-negative organisms such as "S. epidermidis" or "S. saprophyticus". However, it is now known that not all "S. aureus" are coagulase-positive.
It is also produced by "Yersinia pestis".
Coagulase reacts with prothrombin in the blood. The resulting complex is called "staphylothrombin", which enables the enzyme to act as a protease to convert fibrinogen, a plasma protein produced by the liver, to fibrin. This results in clotting of the blood. Coagulase is tightly bound to the surface of the bacterium "S. aureus" and can coat its surface with fibrin upon contact with blood. The fibrin clot may protect the bacterium from phagocytosis and isolate it from other defenses of the host. The fibrin coat can therefore make the bacteria more virulent. Bound coagulase is part of the larger family of MSCRAMM adhesin proteins.
Coagulase test.
The coagulase test has traditionally been used to differentiate "Staphylococcus aureus" from coagulase-negative staphylococci. "S.aureus" produces two forms of coagulase (i.e., bound coagulase and free coagulase). Bound coagulase, otherwise known as "clumping factor", can be detected by carrying out a slide coagulase test, and free coagulase can be detected using a tube coagulase test.
Slide test.
A slide coagulase test is run with a negative control to rule out autoagglutination. Two drops of saline are put onto the slide labeled with sample number, Test (T) and control (C). The two saline drops are emulsified with the test organism using a wire loop, straight wire, or wooden stick. A drop of plasma (rabbit plasma anticoagulated with EDTA is recommended) is placed on the inoculated saline drop corresponding to test, and mixed well, then the slide is rocked gently for about 10 seconds.
If the slide coagulase test is negative, a tube test should follow as a confirmation. Clumping in both drops is an indication of autoagglutination, so a tube test should be carried out. Tube test is not performed each institutions but most of the result depends on blood cultures from lab.
Tube test.
The tube test uses rabbit plasma that has been inoculated with a staphylococcal colony (i.e., Gram-positive cocci which are catalase positive). The tube is then incubated at 37 °C for 1.5 hours. If negative, then incubation is continued up to 18 hours.


Monascus pallens

Monascus pallens is a fungal species in the Monascaceae family. It was found during a survey done on water and sediment of the Shatt al-Arab river in Basra, Iraq. The research was done by Dr. Basil A. Abbas under supervision of SK. Abdullah in 1995.


Natal multimammate mouse

The Natal multimammate mouse ("Mastomys natalensis") is a species of rodent in the family Muridae. It is also known as the Natal multimammate rat, the common African rat, or the African soft-furred mouse.
Range.
It is found in Africa south of the Sahara, that is in Angola, Benin, Botswana, Burkina Faso, Burundi, Cameroon, the Central African Republic, Chad, the Republic of the Congo, the Democratic Republic of the Congo, Ivory Coast, Equatorial Guinea, Ethiopia, Gabon, Ghana, Guinea, Guinea-Bissau, Kenya, Lesotho, Malawi, Mali, Mauritania, Mozambique, Namibia, Niger, Nigeria, Rwanda, Senegal, Sierra Leone, Somalia, South Africa, Sudan, Eswatini, Tanzania, Togo, Uganda, Zambia, and Zimbabwe. Six different genetic groups can be distinguished in different regions: one in western Africa, one in central Africa, one in southern Africa and three in eastern Africa.
Habitat.
Its natural habitats are subtropical or tropical dry forest, subtropical or tropical moist lowland forest, dry savanna, moist savanna, subtropical or tropical dry shrubland, subtropical or tropical moist shrubland, arable land, pastureland, rural gardens, urban areas, irrigated land, and seasonally flooded agricultural land.
These rats associate closely with humans, and are commonly found in and around African villages.
In 1972, the Natal multimammate rat was found to be the natural host of the Lassa fever virus.
Interactions with humans.
The species has been used as a laboratory animal since 1939. It has great value for researchers who focused on stomach cancer and spontaneous tumors. It is also the most important reservoir of Lassa virus.


Dianthovirus

Dianthovirus is a genus of viruses, in the family "Tombusviridae". Dianthoviruses are plant viruses. There are three species in this genus. The virus probably has a worldwide distribution, and can be transmitted via nematodes, by mechanical inoculation, by grafting of plants and by contact between infected hosts with previously uninfected host.
Taxonomy.
The genus contains the following species:
Structure.
Viruses in "Dianthovirus" are non-enveloped, with icosahedral and spherical geometries, a “hexagonal” appearance, and T=3 symmetry. The diameter is around 28-34 nm. Genomes are linear and segmented, bipartite, around 11.3-1.4kb in length. The buoyant density in CsCl of virions is between 1.363-1.366 g cm-3. They have a sedimentation coefficient of 126-132-135 S20w. The pH of their isoelectric point is 4.5. The virions become inactive from about 80-90 °C and are inactive above those temperatures. They are viable in vitro for about 50–70 days. Treatment with ether either decreases or does not alter their infectivity. No lipids have so far been reported.
Life cycle.
Viral replication is cytoplasmic. Entry into the host cell is achieved by penetration into the host cell. Replication follows the positive stranded RNA virus replication model. Positive stranded RNA virus transcription, using the premature termination model of subgenomic RNA transcription is the method of transcription. Translation takes place by -1 ribosomal frameshifting. The virus exits the host cell by tubule-guided viral movement. Plants serve as the natural host. Transmission routes are mechanical, seed borne, and contact.
Genome.
These viruses have segmented, bipartite genomes that are linear, positive-sense, single-stranded RNA (1). These genomes are about 5300 nucleotides in length (1). They have a methylated cap at the 5'-end whose sequence type is m7GpppA (1). The genome also codes for non-structural proteins as well as structural proteins (1). Three non-structural proteins have been found (1).


Knoellia locipacati

Knoellia locipacati is a species of Gram positive, nonmotile, non-sporeforming bacteria. The bacteria are aerobic and mesophilic, and the cells can be irregular rods or coccoid. It was originally isolated from soil from the Korean Demilitarized Zone. The species name is derived from Latin "locus" (a place, country region) and "pacatus" (pacified, peaceful, quiet).
The optimum growth temperature for "K. locipacati" is 30 °C and can grow in the 10-37 °C range. The optimum pH is 7.0-8.0, and can grow in pH 6.0-9.0.


Gomphidius roseus

Gomphidius roseus, commonly known as the rosy spike-cap or pink gomphidius, is a gilled mushroom found in Europe. Although it has gills, it is a member of the order Boletales, along with the boletes. It is a coral pink-capped mushroom which appears in pine forests in autumn, always near the related mushroom "Suillus bovinus", on which it appears to be parasitic.
Taxonomy.
"Gomphidius roseus" was initially described by Swedish mycologist Elias Magnus Fries as "Agaricus glutinosus β roseus" in 1821, before he elevated it to species status and gave its current genus and binomial name in 1838. The genus name is derived from the Greek 'γομφος' "gomphos" meaning "plug" or "large wedge-shaped nail". The specific epithet "roseus" is the Latin adjective "pink".
Description.
The mushroom has a coral-pink cap up to in diameter, though sometimes larger, which is initially convex and later flattens and becomes a more brick-like colour with maturity. Often slimy or sticky as with other members of the genus, its cap lacks the blackish markings of the related "G. glutinosus". The stipe is high and 0.4–1 cm wide and bears an indistinct ring. It is white with a pinkish or wine-coloured tint and often flushed yellow at the base. The whitish flesh may also be tinged pink and has little taste or smell. The decurrent gills are grey, and the spore print is brownish-black.
Distribution and habitat.
An uncommon fungus, "Gomphidius roseus" is found in Europe, but not in North America. A similar pinkish species, "G. subroseus" occurs in North America. It is found in pine woods, particularly "Pinus sylvestris", associated with "Suillus bovinus", and is often hidden in undergrowth. Fruiting bodies sprout in the autumn.
Ecology.
Like other members of the family Gomphidiaceae, "Gomphidius roseus" has been thought to be ectomycorrhizal, forming symbiotic relationship with their host trees. However, it is found exclusively with the related Jersey cow mushroom ("Suillus bovinus"), and is now thought to be parasitic upon its mycelium. This is evidenced by microscopic examination, which shows that "G. roseus" inserts haustoria in plant root cells and does not produce significant mycelium itself. Furthermore, "G. roseus" is never found growing in isolation, only with "S. bovinus" though the latter species is found without the former.
Edibility.
"Gomphidius roseus" is not known to be toxic but is reported to be of poor quality and hence not recommended for picking.


Phosphate solubilizing bacteria

Phosphate solubilizing bacteria (PSB) are beneficial bacteria capable of solubilizing inorganic phosphorus from insoluble compounds. P-solubilization ability of rhizosphere microorganisms is considered to be one of the most important traits associated with plant phosphate nutrition. It is generally accepted that the mechanism of mineral phosphate solubilization by PSB strains is associated with the release of low molecular weight organic acids, through which their hydroxyl and carboxyl groups chelate the cations bound to phosphate, thereby converting it into soluble forms. PSB have been introduced to the Agricultural community as phosphate Biofertilizer. Phosphorus (P) is one of the major essential macronutrients for plants and is applied to soil in the form of phosphate fertilizers. However, a large portion of soluble inorganic phosphate which is applied to the soil as chemical fertilizer is immobilized rapidly and becomes unavailable to plants. Currently, the main purpose in managing soil phosphorus is to optimize crop production and minimize P loss from soils. PSB have attracted the attention of agriculturists as soil inoculums to improve the plant growth and yield. When PSB is used with rock phosphate, it can save about 50% of the crop requirement of phosphatic fertilizer. The use of PSB as inoculants increases P uptake by plants. Simple inoculation of seeds with PSB gives crop yield responses equivalent to 30 kg P2O5 /ha or 50 percent of the need for phosphatic fertilizers. Alternatively, PSB can be applied through fertigation or in hydroponic operations. Many different strains of these bacteria have been identified as PSB, including "Pantoea agglomerans" (P5), "Microbacterium laevaniformans" (P7) and "Pseudomonas putida" (P13) strains are highly efficient insoluble phosphate solubilizers. Recently, researchers at Colorado State University demonstrated that a consortium of four bacteria, synergistically solubilize phosphorus at a much faster rate than any single strain alone. Mahamuni and Patil (2012) isolated four strains of phosphate solubilizing bacteria from sugarcane (VIMP01 and VIMP02) and sugar beet rhizosphere (VIMP03 and VIMP 04). Isolates were strains of "Burkholderia" named as VIMP01, VIMP02, VIMP03 and VIMP04. VIMP (Vasantdada Sugar Institute Isolate by Mahamuni and Patil) cultures were identified as "Burkholderia cenocepacia" strain VIMP01 (JQ867371), "Burkholderia gladioli" strain VIMP02 (JQ811557), "Burkholderia gladioli" strain VIMP03 (JQ867372) and "Burkholderia species" strain VIMP04 (JQ867373)6].
Additionally, phosphate (P) compounds are capable of immobilizing heavy metals, especially Pb, in contaminated environments through phosphate-heavy metal precipitation. However, most P compounds are not readily soluble in soils so it is not readily used for metal immobilization. Phosphate solubilizing bacteria (PSB) have the potential to enhance phosphate-induced immobilization of metals to remediate contaminated soil. However, there is a limit on the amount of phosphate which can be added to the environment due to the issue of eutrophication.
Phosphate is often adsorbed onto the surface of different type of minerals, for example iron containing minerals. Recent data suggest that bacteria growing under phosphorus starvation release iron-chelating molecules. Considering the geochemical interaction between these two elements, the authors suggest that some bacteria can dissolve iron-containing minerals in order to access the adsorbed phosphate.


Mycobacterium diernhoferi

Mycobacterium diernhoferi is a species of the phylum Actinobacteria (Gram-positive bacteria with high guanine and cytosine content, one of the dominant phyla of all bacteria), belonging to the genus "Mycobacterium".
Description.
Gram-positive, nonmotile and acid-fast rods (2-6 µm x 0.5 µm).
Colony characteristics
Physiology
Differential characteristics
Belongs to the "Mycobacterium parafortuitum" complex. Which unifies rapidly growing, scotochromogenic mycobacteria ("M. parafortuitum", "Mycobacterium aurum", "Mycobacterium neoaurum", "M. diernhoferi" and "Mycobacterium austroafricanum").
Type strain.
First isolated from soil in a cattle field (Germany).
Strain 41001 = ATCC 19340 = CIP 105384 = DSM 43524 = HAMBI 2269 = IFO (now NBRC) 14756 = JCM 6371.


Legionella clemsonensis

Legionella clemsonensis was isolated in 2006, but was discovered in 2016 by Clemson University researchers. It is a Gram-negative bacterium.
Taxonomic and phylogenetic description.
“"Legionella"” is named after the American Legion convention where the first outbreak occurred, killing 34 people and sickening 221 individuals in 1976. It occurred in Philadelphia during the convention for the association of the U.S. veterans. The specific name "clemsonensis"” derives from Clemson University, where undergraduates DNA-sequenced this new strain. "Legionella" has a correlation with another genus called "Coxiella". Both cause lung infection that can eventually lead to pneumonia due to the intracellular bacteria in aerosols.
Discovery.
Based on physical characteristics, phylogenetic analysis, and membrane fatty-acid composition, the organism was found to represent a unique lineage within the "Legionella" bacteria. The specific strain for "Legionella clemsonensis" is D5610. It was named in honor of the research group of students from the Clemson’s Creative Inquiry. "Legionella clemsonensis" was first isolated in 2006 from the bronchial wash of a patient diagnosed with pneumonia. Bronchial washing is part of a bronchoscopy procedure. After being isolated and stored, strain D5610 was acquired by the Centers for Disease Control and Prevention (CDC), which sent 68 strains of "Legionella", including strain D5610, for students to analyze at Clemson. When isolated, it was shown to be very similar to bacterial genus "Legionella". Researchers stated "it was identified as "Legionella" based on sequencing, cellular fatty-acid analysis, biochemical reactions, and biofilm characterization." For a physical characterization of "L.a clemsonensis", it was streaked for a single colony isolation using a charcoal yeast extract agar and required cysteine for primary isolation. No growth was shown, which is typical of "Legionella" strains. A characteristic of "L. clemsonensis" is that it has a single, polar flagellum. Researchers also used fatty-acid methyl-ester analyses to distinguish differences between the "Legionella" strains. Cellular fatty-acid composition was analyzed using a Sherlock microbial Identification System.
Preliminary characterization.
"L. clemsonensis" was determined as a special lineage within the genus "Legionella" based on its phylogenetic analysis and physical appearance. It is a Gram-negative bacterium that is rod-shaped with one polar flagellum to help it move around. The strain can grow between 26 and 45 °C, forming biofilms that are similar to "L. pneumophila" Philadelphia 1. The strain D5610 of "L. clemsonensis" shows a distinctive temperature constraint compared to many of the "Legionella" species that do not grow under 26 °C and a restriction of temperatures above 45 °C . Most "Legionella" species have the ability to grow as high as 63 °C and very slowly at temperatures as low as 5 °C. At both 37 and 26 °C, strain D5610 was found to grow more slowly than "L. pneumophila" Philadelphia 1, and it also formed a significant amount of pigment that was less produced. These attributes suggest that this isolation is a standard "Legionella" species, for which the name "Legionella clemsonensis" was used. "Legionella" is considered to be pathogenic in humans and is one of the leading outbreaks found in constructed water systems. Because the biofilms are the source, countless outbreaks that originated from water systems and the ability of a species to form biofilms both can contribute to "L. clemonensis’s" pathogenicity. The process of characterizing and sequencing the strain D5610 is still undergoing investigation. Because this strain is still being investigated, no specific metabolism has been shown for "L. clemsonensis". Yet, "Legionella’s" usual metabolism is a facultative intracellular pathogen that increases in large numbers inside free-living amoebae, as well as macrophages and other protozoa. In water systems, the pathogen lives in low metabolic state in the biofilms. A known strain of Legionella called in vitro "L. pneumophila" does not grow on standard media such as blood agar, because of a pH of 6.9 and certain amino acids such as cysteine being required. Yet when these requirements are met, the growth in the aerobic conditions is still slow. Up to 5 days are needed for colonies to be produced. The genomics have yet to be stated for this particular strain of "Legionella", as well as the habitats.
Importance.
"L. clemsonensis" is pathogenic; most "Legionella" species are commonly known to cause pneumonia. A feature that sets "L. clemsonensis" apart is that under ultraviolet light, it fluoresces green, which differs from other "Legionella" strains because they usually fluoresce blue, red, or yellow.


Bacillales

The Bacillales are an order of Gram-positive bacteria, placed within the Firmicutes. Representative genera include "Bacillus", "Listeria" and "Staphylococcus".


Kribbia dieselivorans

Kribbia dieselivorans is a species of Gram positive, nonmotile, non-sporeforming bacteria. The bacteria are facultatively anaerobic and mesophilic, and the cells can be irregular rods or coccoid. It was originally isolated from tidal flat sediment collected from Kwangyang, South Korea during a survey for diesel-degrading bacteria. The species name refers to its ability to degrade diesel fuel. "K. dieselivorans" is the type species of genus "Kribbia", and is currently the only species in the genus.
The optimum growth temperature for "K. dieselivorans" is 30 °C and can grow in the 8-42 °C range. The optimum pH is 6.5-7.5.


Korarchaeum cryptofilum


Malassezia

Malassezia (formerly known as Pityrosporum) is a genus of fungi. Malassezia is naturally found on the skin surfaces of many animals, including humans. In occasional opportunistic infections, some species can cause hypopigmentation or hyperpigmentation on the trunk and other locations in humans. Allergy tests for this fungus are available.
Nomenclature.
Due to progressive changes in their nomenclature, some confusion exists about the naming and classification of "Malassezia" yeast species. Work on these yeasts has been complicated because they require specific growth media and grow very slowly in laboratory culture.
"Malassezia" were originally identified by the French scientist Louis-Charles Malassez in the late 19th century. Raymond Sabouraud identified a dandruff-causing organism in 1904 and called it "Pityrosporum malassez", honoring Malassez, but at the species level as opposed to the genus level. When it was determined that the organisms were the same, the term "Malassezia" was judged to possess priority.
In the mid-20th century, it was reclassified into two species:
In the mid-1990s, scientists at the Pasteur Institute in Paris, France, discovered additional species.
Species.
, Species Fungorum accepts 22 species of "Malassezia". The following list gives the name of the fungus, the taxonomic authority (those who first described the fungus, or who transferred it into "Malassezia" from another genus; standardized author abbreviations are used), and the name of the organism from which the fungus was isolated, if not human.
Role in human diseases.
Dermatitis and dandruff.
Identification of "Malassezia" on skin has been aided by the application of molecular or DNA-based techniques. These investigations show that the "Malassezia" species causing most skin disease in humans, including the most common cause of dandruff and seborrhoeic dermatitis, is "M. globosa" (though "M. restricta" is also involved). The skin rash of tinea versicolor ("pityriasis versicolor") is also due to infection by this fungus.
As the fungus requires fat to grow, it is most common in areas with many sebaceous glands: on the scalp, face, and upper part of the body. When the fungus grows too rapidly, the natural renewal of cells is disturbed, and dandruff appears with itching (a similar process may also occur with other fungi or bacteria so differential diagnosis should be made).
A project in 2007 has sequenced the genome of dandruff-causing "Malassezia globosa" and found it to have 4,285 genes. "M. globosa" uses eight different types of lipase, along with three phospholipases, to break down the oils on the scalp. Any of these 11 proteins would be a suitable target for dandruff medications.
The number of specimens of "M. globosa" on a human head can be up to ten million.
"M. globosa" has been predicted to have the ability to reproduce sexually, but this has not been observed.
Research.
"Malassezia" is among the many mycobiota undergoing laboratory research to investigate whether it is associated with types of disease.


Ancyromonadida

Ancyromonadida or Planomonadida is a small group of biflagellated protists found in the soil and in aquatic habitats, where they feed on bacteria. Includes freshwater or marine organisms, benthic, dorsoventrally compressed and with two unequal flagellae, each emerging from a separate pocket. The apical anterior flagellum can be very thin or end in the cell membrane, while the posterior flagellum is long and is inserted ventrally or laterally. The cell membrane is supported by a thin single layer teak and the mitochondrial crests are discoidal / flat.
The group's placement is doubtful, as it seems to fall outside the five supergroups of Eukarya. Cavalier-Smith considers that they constitute a basal group to Amoebozoa and Opisthokonta and places it together with other related groups in Sulcozoa. However, they appear more basal than Malawimonas, placing them in Loukouzoa, possibly as stem podiates, and depending on the placement of the root position of the Eukaryotes.


Rice ragged stunt virus

Rice ragged stunt virus (RRSV) is a plant pathogenic virus of the family "Reoviridae".
RRSV, vectored by the brown planthopper (BPH) (Delphacidae: "Nilaparvata lugens"), causes ragged stunt disease of rice ("Oryza" spp., especially "Oryza sativa"). The virus, first described by Hibino, Ling and Shikata, is also less commonly known as rice infectious gall virus. RRSV has polyhedral particles about 50 nm in diameter possessing spikes (and perhaps a complete outer shell) to a diameter of 65 nm. The particles contain double-stranded RNA in eight segments. RRSV can only infect plants in the family Gramineae, i.e. grasses including rice. The virus can only be transmitted by BPH and is not mechanically transmitted to plants.
Rice plants infected with RRSV are stunted with whitish spindle-shaped outgrowths. Later the infected leaves become twisted with ragged edges, and may eventually turn brown. Rice plants may survive the infection, but yields are greatly reduced due to delayed flowering, incomplete panicle emergence, and unfilled grains. Symptoms of RRSV infection vary with the variety of rice and stage of growth. Most rice varieties of "Oryza sativa japonica" and "Oryza sativa indica" are susceptible to RRSV though several resistant varieties are available. Attempts to prevent RRSV infections by controlling BPH with insecticides often have the opposite effect of facilitating RRSV outbreaks; this can be due to a disproportionate effect of insecticides on the natural enemies of BPH. Certain types of insecticides (e.g., triazophos) increase the birthrates of BPH through their effects on the reproductive systems of male and female planthoppers. The increase in BPH populations not only increases the incidence of RRSV within a field, but as the BPH become crowded they transform into long-winged migratory forms (known as macropterous forms) and spread RRSV to fields up to hundreds of kilometers away.
During an outbreak it is difficult to distinguish RRSV yield losses from losses caused by BPH feeding. BPH also vectors rice grassy stunt virus (RGSV). It is often not possible to quantify how much of the crop loss was due to RRSV, RGSV, or BPH feeding damage. Field trials in Indonesia indicate that with a rice ragged stunt incidence of 34–76%, grain yields are only 17–47% of healthy plant yields. RRSV has been reported from China, India, Indonesia, Japan, Malaysia, the Philippines, Sri Lanka, Taiwan, Thailand, and Vietnam. Presence of RRSV is suspected, but not confirmed, in Cambodia, Lao PDR (Laos), and Myanmar (Burma). There were major outbreaks of RRSV and RGSV in China and Vietnam in 2006–2007.


Acaulospora scrobiculata

Acaulospora scrobiculata is a species of fungi in the family Acaulosporaceae. It forms arbuscular mycorrhiza and vesicles in roots.


Beta dispersion

Beta dispersion is the phenomenon associated with the ability of a biological cell membrane to filter out low frequency currents and allow high frequency currents to pass through. It was originally hypothesized by Rudolf Höber in 1910 and confirmed through a series of experiments between 1910 and 1913.
Höber observed that living tissue has greater electrical resistance compared to dead tissue and that there could be two reasons for this.His first hypothesis was that ions do not pass freely through the cell surface. This property maintains ions within the cell. Upon cell death, the insulating property of the cell membrane is lost. He also hypothesized that electrolytes within the cell were bound to internal structures and would dissociate from these structures during cell death and would then be able to exit the cell. Höber then performed a series of experiments to test these hypotheses.
Höber used centrifugation to obtain a dense pellet of red blood cells then measured the conductivity of the cell sample at low frequencies (100 – 200 Hz) by using methods developed by Friedrich Kohlrausch. It was determined that the cells had a conductivity equal to 0.02% NaCl solution.
Next, an oscillatory circuit was built to measure the conductivity of the cell samples at high frequencies. NaCl solutions of varying concentrations or cell samples were used as a varying capacitor within the circuit. The dampening effect on the oscillating current was compared in the NaCl solutions and the compacted cell samples to determine the cell conductivity. Through optimization of the circuit and further experimentation with blood cells and frog leg muscle cells, Höber determined that blood cells have a conductivity equal to 0.18% NaCl solution when subjected to high frequencies(1 - 10 MHz).
Hober found that, at high frequencies, the cell conductivity was about five times greater compared to conductivity at low frequencies. This suggested that electrical current would flow around the outer surface of the cell at low frequencies, but at high frequencies, could pass through the cellular envelope and travel through the ion-rich intracellular environment. After inducing pores in the cell membrane and subjecting the cell sample to low frequency current, a much higher conduction was observed compared previousdata. This verified that the conductivity being measured was indeed the conductivity of the fluid within the cell.
This work served as the basis for what is known as beta dispersion and also served as proof that cells have a high internal concentration of free ions, which is maintained by a membrane through which ions can not freely pass.


MycoBank

MycoBank is an online database, documenting new mycological names and combinations, eventually combined with descriptions and illustrations. It is run by the Centraalbureau voor Schimmelcultures fungal biodiversity center in Utrecht.
Each novelty, after being screened by nomenclatural experts and found in accordance with the ICN (International Code of Nomenclature for algae, fungi, and plants), is allocated a unique MycoBank number before the new name has been validly published. This number then can be cited by the naming author in the publication where the new name is being introduced. Only then, this unique number becomes public in the database.
By doing so, this system can help solve the problem of knowing which names have been validly published and in which year.
MycoBank is linked to other important mycological databases such as Index Fungorum, Life Science Identifiers, Global Biodiversity Information Facility (GBIF) and other databases. MycoBank is one of three nomenclatural repositories recognized by the Nomenclature Committee for Fungi; the others are Index Fungorum" and Fungal Names.


Immunome

The immunome is the set of genes and proteins that constitute the immune system, excluding those that are widespread in other cell types, and not involved in the immune response itself. It is further defined as the set of peptides derived from the proteome that interact with the immune system. There are numerous ongoing efforts to characterize and sequence the immunomes of humans, mice, and elements of non-human primates. Typically, immunomes are studied using immunofluorescence microscopy to determine the presence and activity of immune-related enzymes and pathways.
Practical applications for studying the immunome include vaccines, therapeutic proteins, and further treatment of other diseases. The study of the immunome falls under the field of immunomics.
Etymology.
The word immunome is a portmanteau of the words "immune" and "chromosome." See omics for a further discussion.
Efforts to characterize.
The exact size of the human immunome is currently unknown and has been a topic of study for decades. However, the amount of information it encodes is said to exceed the size of the human genome by several orders of magnitude due to, at least in part, somatic hypermutation and junctional diversity. There are several ongoing efforts to characterize the immunomes of humans and other species.
One major effort, launched in 2016, is a collaborative project between The Human Vaccines Project, Vanderbilt University Medical Center, and Illumina, Inc.. This project is entitled the Human Immunome Program and its goal is to decipher the complete collection of B and T immune cell receptors from the human population. Thousands of individuals will need to be studied in order to meet this goal, and they will need to represent different ages, genders, ethnicities, and geographical origins. Furthermore, people with diseases and people who have undergone vaccination will need to be studied as well. The results of the program will be shared as an open-sourced database. The sequencing project will continue until no new unique sequences occur within the B and T cell receptors and is expected to take ten years.
Similarly, there is a research project called the Immunological Genome Project whose stated goal is to generate "a complete microarray dissection of gene expression and its regulation in the immune system of the mouse". In other words, the project is trying to define and characterize the immunome of the mouse. This project is primarily intended to function as a primary resource and the researchers actively accept suggestions from the community. The project team consists of more than 20 research labs, all working on various aspects of the project, including studying T cells, B cells, and dendritic cells, along with many other types of cells within the mouse immunome. The project has been ongoing since 2008.
Efforts are also being made to characterize aspects of non-human immunomes, particularly non-human primates because of their genetic similarity to humans.
Methods of study.
In order to gain useful knowledge about the immunome and its characteristics, the cells and components of the immune system must be phenotyped in a quick and pragmatic manner. There are hundreds of known cell types within the immune system and the possibility of detecting and characterizing them without the use of recent advances in immunophenotyping technology was remote because large amounts of an individual's blood would have been required. This outdated method is called low-dimensional immunophenotyping. However, high-dimensional immunophenotyping is now a possibility. The types of high-dimensional immunophenotyping can be broadly grouped into two categories: the use of isotopes of lanthanide and the use of fluorophores. These advanced technologies allow for up to 100 parameters to be measured at one time.
Applications.
There are potentially far-reaching applications for studying the immunome. Dr. Anne De Groot believes that knowledge gained from the immunome could lead to discovering differences in the absolute number of T cell epitopes, and could reveal antigenic relationships between different but immunologically similar pathogens. She further states that there are possibilities for autoimmune disease therapies and organ transplantation.
Immunome investigation has proven useful in determining the symptoms and potential causes of pulmonary fibrosis on a molecular level.
The development of vaccines is also an application of immunome study as shown by Carlos F. Suárez and his colleagues. They were able to find components of a malaria vaccine that could be readily used in humans as a result of having characterized the cell surface receptor of an immune cell from an owl monkey. These monkeys have been shown to be highly susceptible to human malaria, so they serve as a good model for the disease. It could also be possible to develop an influenza vaccine that would provide protection from several strains of the virus.
Furthermore, analyzation of the immunomes of non-human primates and other species can reflect the evolutionary history of species as shown by David F. Plaza and his colleagues. This immunome data can also be helpful when testing antibody therapies on non-human primates to ensure they are safe for humans. This can be accomplished by being able to interpret results in the context of the slight differences in ortholog structure between the human and non-human primate immunomes.
Databases.
There are a number of databases corresponding to the different facets of the human immunome and the immunomes of other species.
Immunome Knowledge Base (IKB).
An effort is being made to assemble immunological information into a singular database called the Immunome Knowledge Base(IKB). The two scientists behind the effort, Csaba Ortutay & Mauno Vihinen, have integrated data from three separate databases into IKB. These three databases, Immunome, ImmTree, and ImmunomeBase, all have separate, but related information pertaining to the immunome. Immunome contains entries to official gene names according to the HUGO Gene Nomenclature Committee, alternative names, and locations of genes on the chromosomes. ImmTree contains entries related to the molecular evolution of the immune system, including orthologous genes and phylogenetic trees. Finally, ImmunomeBase is a multi-species database related to immunity. Altogether, as of 2009, IKB has entries for more than 100,000 data items, including 893 entries for genes in the immunome.
Immune Epitope Database (IEDB).
This database serves as a resource for data on antibody and T cell epitopes studied in humans, non-human primates, and other species as it relates to disease, allergies, autoimmunity, and transplantation. The database also has tools to assist in the prediction and analysis of epitopes.
Immunome Database for Marsupials and Monotremes (IDMM).
This database has data for every known marsupial and monotreme immune gene. It serves as a resource for immunologists and researchers studying the evolution of mammalian immunity.
Immunology Database and Analysis Portal (ImmPort).
A database developed for the purpose of promoting the re-use of immunological data. It is a partnership between researchers at the University of California-San Francisco, Stanford University, the University of Buffalo, the Technion - Israel Institute of Technology, and Northrop Grumman. It encompasses results from over 400 studies related to immunology.
Immunological Genome Project (ImmGen).
This database is a public resource containing the data relating to the study of the immune system of the mouse.


Mallomonas pleuriforamen

Mallomonas pleuriforamen is an extinct species of heterokont algae. It was first found in Middle Eocene lacustrine deposits from northwestern Canada. It was a tiny free-living cell, about the width of a human hair. It had ornate scales and bristles, as well as long spines. It was a relatively common part of lake or pond plankton. It differs from its cogenerates by the number, distribution, and size of its base plate pores, the secondary structures on the scale surfaces, together with characteristics of its bristles.


Biomarker (cell)

A biomarker, or biological marker, is defined as a "cellular, biochemical or molecular alteration in cells, tissues or fluids that can be measured and evaluated to indicate normal biological processes, pathogenic processes, or pharmacological responses to a therapeutic intervention."Biomarkers characterize disease progression starting from the earliest natural history of the disease. Biomarkers assess disease susceptibility and severity, which allows one to predict outcomes, determine interventions and evaluate therapeutic responses. From a forensics and epidemiologic perspective, biomarkers offer unique insight about the relationships between environmental risk factors.
Classes of Biomarkers.
Three broad classes of biomarkers are prognostic biomarkers, predictive biomarkers and pharmacodynamic biomarkers.
Prognostic Biomarkers.
Prognostic biomarkers give intervention-independent information on disease status through screening, diagnosis and disease monitoring. Prognostic biomarkers can signify individuals in the latent period of a disease's natural history, allowing optimal therapy and prevention until the disease's termination. Prognostic biomarkers give information on disease status by measuring the internal precursors that increase or decrease the likelihood of attaining a disease. For example, blood pressure and cholesterol are biomarkers for CVD. Prognostic biomarkers can be direct or indirect to the causal pathway of a disease. If a prognostic biomarker is a direct step in the causal pathway, it is one of the factors or products of the disease. A prognostic biomarker could be indirectly associated with a disease if it is related to a change caused by the exposure, or related to an unknown factor connected with the exposure or disease.
Predictive Biomarkers.
Predictive biomarkers measure the effect of a drug and tell if the drug is having its expected activity, but do not offer any direct information on the disease. Predictive biomarkers are highly sensitive and specific; therefore they increase diagnostic validity of a drug or toxin's site-specific effect by eliminating recall bias and subjectivity from those exposed. For example, when an individual is exposed to a drug or toxin, the concentration of that drug or toxin within the body, or the biological effective dose, provides a more accurate prediction for the effect of the drug or toxin compared to an estimation or measurement of the toxin from the origin or external environment.
Pharmacodynamic Biomarkers.
Pharmacodynamic (PD) biomarkers can measure the direct interaction between a drug and its receptor. Pharmacodynamic biomarkers reveal drug mechanisms, if the drug has its intended effect on the biology of the disease, ideal biological dosing concentrations, and physiologic response/resistance mechanisms. Pharmacodynamic biomarkers are particularly relevant in drug mechanisms of tumor cells, where pharmacodynamic endpoints for drug interventions can be assessed directly on tumor tissues. For example, protein phosphorylation biomarkers indicate alterations in target protein kinases and activation of downstream signaling molecules.
Clinical Applications for Biomarkers.
Biomarkers can be classified on their clinical applications as molecular biomarkers, cellular biomarkers or imaging biomarkers.
Molecular Biomarkers.
Four of the main types of molecular biomarkers are genomic biomarkers, transcriptomic biomarkers, proteomic biomarkers and metabolic biomarkers.
Genomic Biomarkers.
Genomic biomarkers analyze DNA by identifying irregular sequences in the genome, typically a single nucleotide polymorphism. Genetic biomarkers are particularly significant in cancer because most cancer cell lines carry somatic mutations. Somatic mutations are distinguishable from hereditary mutations because the mutation is not in every cell; just the tumor cells, making them easy targets.
Transcriptomic Biomarkers.
Transcriptomic biomarkers analyze all RNA molecules, not solely the exome. Transcriptomic biomarkers reveal the molecular identity and concentration of RNA in a specific cell or population. Pattern-based RNA expression analysis provides increased diagnostic and prognostic capability in predicting therapeutic responses for individuals. For example, distinct RNA subtypes in breast cancer patients have different survival rates.
Proteomic Biomarkers.
Proteomics permits the quantitative analysis and detection of changes to proteins or protein biomarkers. Protein biomarkers detect a variety of biological changes, such as protein-protein interactions, post-translational modifications and immunological responses.
Cellular Biomarkers.
Cellular biomarkers allow cells to be isolated, sorted, quantified and characterized by their morphology and physiology. Cellular biomarkers are used in both clinical and laboratory settings, and can discriminate between a large sample of cells based on their antigens. An example of a cellular biomarker sorting technique is Fluorescent-activated cell sorting.
Imaging Biomarkers.
Imaging biomarkers allow earlier detection of disease compared to molecular biomarkers, and streamline translational research in the drug discovery marketplace. For example, one could determine the percent of receptors a drug targets, shortening the time and money of research during the new drug development stage. Imaging biomarkers also are non-invasive, which is a clinical advantage over molecular biomarkers. Some of the image-based biomarkers are X-Ray, Computed Tomography (CT), Positron Emission Tomography (PET), Single Photo Emission Computed Tomography (SPECT) and Magnetic Resonance Imaging (MRI).


Paramastigaceae


Triparma

Triparma is a genus of unicellular algae in the family Triparmaceae in the order Parmales. They form siliceous plates on the cell surface that aid in identification. "Triparma" is distinguished by its possession of three shield plates, three triradiate girdle plates, a triradiate girdle plate with notched ends, and a small ventral plate. It was first described by Booth & Marchant in 1987 and the holotype is "Triparma columacea".
"Triparma" cells have two forms: the motile, naked form and the non-motile siliceous form. The motile cells propelled by two flagella of unequal length, typical of heterokonts. The non-motile forms do not possess flagella but instead have a silicified cell wall with a distinctive plate morphology: three shield plates, three oblong girdle plates, a triradiate dorsal plate with rounded ends, and a large ventral plate. Both forms contain a single, dorsal chloroplast that contains chlorophylls "a" and "c1-3" as well as fucoxanthin. They are typically 1-2 μm in size and generally spherical or heart-shaped.
The genus "Triparma" is actively studied because of their close relationship to the diatoms, and it has been discovered that they have different silica-limitation responses. While diatoms stop growing and cell division is inhibited under low-silica conditions, "Triparma" continues to grow and divide normally even under nanomolar concentrations of silica, although the silica plates are no longer produced.
Photosynthetic pigments present in bolydophyte chloroplasts include chlorophylls a, c1, c2, c3, fucoxanthin, diatoxanthin, diadinoxanthin.
Synonyms.
The genus now includes all species from the non-monophyletic genus "Bolidomonas", according to Ichinomiya "et al" (2016).


Saccharomycetes

Saccharomycetes belongs to the kingdom of Fungi and the division Ascomycota. It is the only class in the subdivision Saccharomycotina, the budding yeasts. Saccharomycetes contains a single order: Saccharomycetales.
References.
Saccharomycetes are known for being able to comprise a monophyletic lineage with a single order of about 1000 known species. These yeasts live as decomposers, feeding on dead and decaying wood, leaves, litter, and other organic matter. According to the article "Phylogenetics of Saccharomycetales,the ascomycete yeasts" the author states "yeasts are responsible for important industrial and biotechnological processes, including baking, brewing and synthesis of recombinant proteins"(Blackwell M). The author also considers saccharomycetes to be model organisms in research. Asia is likely to be the origin of the source.
Reference
Blackwell, B(2006, NOV 6). Phylogenetics of Saccharomycetales, the ascomycete yeasts. http://apps.webofknowledge.com/full_record.do?product=WOS&search_mode=GeneralSearch&qid=8&SID=6ALbRzMRklbXdk7UQbm&page=1&doc=6


Alphasphaerolipovirus

Alphasphaerolipovirus is a genus of double stranded DNA viruses that infect haloarchaea. There are four species currently recognized in this genus.
Morphology.
Viruses of this genus are tailless icosahedral virions with an internal lipid membrane located between the protein capsid and the linear double stranded DNA genome.
Note.
The name Halosphaerovirus was also proposed for this genus.


Boletinellus

Boletinellus is a genus of fungi in the family Boletinellaceae (suborder Sclerodermatineae of the Boletales). The genus was first described by American mycologist William Alphonso Murrill in 1909.


Yamata no Orochi

, or simply , is a legendary eight-headed and eight-tailed Japanese dragon/serpent.
Mythology.
Yamata no Orochi legends are originally recorded in two ancient texts about Japanese mythology and history. The 680 AD transcribes this dragon name as and the 720 AD writes it as . In both versions of the Orochi myth, the Shinto storm god Susanoo (or "Susa-no-O") is expelled from Heaven for tricking his sister Amaterasu, the sun goddess.
After expulsion from Heaven, Susanoo encounters two near the head of the , now called the , in Izumo Province. They are weeping because they were forced to give the Orochi one of their daughters every year for seven years, and now they must sacrifice their eighth, , who Susanoo transforms into a for safekeeping. The tells the following version:
So, having been expelled, [His-Swift-impetuous-Male-Augustness] descended to a place [called] Tori-kami (, now ) at the head-waters of the River Hi in the Land of Idzumo. At this time some chopsticks came floating down the stream. So His-Swift-Impetuous-Male-Augustness, thinking that there must be people at the head-waters of the river, went up it in quest of them, when he came upon an old man and an old woman, – two of them, – who had a young girl between them, and were weeping. Then he deigned to ask: "Who are ye?" So the old man replied, saying: "I am an Earthly Deity, child of the Deity Great-Mountain-Possessor. I am called by the name of Foot-Stroking-Elder, my wife is called by the name of Hand-Stroking Elder, and my daughter is called by the name of Wondrous-Inada-Princess." Again he asked: What is the cause of your crying?" [The old man answered] saying: "I originally had eight young girls as daughters. But the eight-forked serpent of Koshi has come every year and devoured [one], and it is now its time to come, wherefore we weep." Then he asked him: "What is its form like?" [The old man] answered, saying: "Its eyes are like , it has one body with eight heads and eight tails. Moreover on its body grows moss, and also chamaecyparis and cryptomerias. Its length extends over eight valleys and eight hills, and if one look at its belly, it is all constantly bloody and inflamed." (What is called here is the modern [winter-cherry]) Then His-Swift-Impetuous-Male-Augustness said to the old man: "If this be thy daughter, wilt thou offer her to me?" He replied, saying: "With reverence, but I know not thine august name." Then he replied, saying: "I am elder brother to the Heaven-Shining-Great-August-Deity. So I have now descended from Heaven." Then the Deities Foot-Stroking-Elder and Hand-Stroking-Elder said: "If that be so, with reverence will we offer [her to thee]." So His-Swift-Impetuous-Male-Augustness, at once taking and changing the young girl into a multitudinous and close-toothed comb which he stuck into his august hair-bunch, said to the Deities Foot-Stroking-Elder and Hand-Stroking-Elder: "Do you distill some eight-fold refined liquor. Also make a fence round about, in that fence make eight gates, at each gate tie [together] eight platforms, on each platform put a liquor-vat, and into each vat pour the eight-fold refined liquor, and wait." So as they waited after having thus prepared everything in accordance with his bidding, the eight-forked serpent came truly as [the old man] had said, and immediately dipped a head into each vat, and drank the liquor. Thereupon it was intoxicated with drinking, and all [the heads] lay down and slept. Then His-Swift-Impetuous-Male-Augustness drew the ten-grasp saber, that was augustly girded on him, and cut the serpent in pieces, so that the River Hi flowed on changed into a river of blood. So when he cut the middle tail, the edge of his august sword broke. Then, thinking it strange, he thrust into and split [the flesh] with the point of his august sword and looked, and there was a great sword [within]. So he took this great sword, and, thinking it a strange thing, he respectfully informed the Heaven-Shining-Great-August-Deity. This is the Herb-Quelling Great Sword. (tr. Chamberlain 1919:71–3)
The also describes Yamata no Orochi: "It had an eight-forked head and an eight-forked tail; its eyes were red, like the winter-cherry; and on its back firs and cypresses were growing. As it crawled it extended over a space of eight hills and eight valleys." The botanical names used to describe this Orochi are or (winter cherry or Japanese lantern, "Physalis alkekengi"), (club moss, "Lycopodiopsida"), (Japanese cypress, "Chamaecyparis obtusa"), and (Japanese cedar, "Cryptomeria").
The legendary sword , which came from the tail of Yamata no Orochi, along with the mirror and jewel, became the three sacred Imperial Regalia of Japan.
Etymology.
The Japanese name derives from Old Japanese (with a regular from shift, but its etymology is enigmatic. Besides this ancient reading, the kanji, , are commonly pronounced , "big snake; large serpent".
Carr (1990:169) notes that Japanese scholars have proposed "more than a dozen" < etymologies, while Western linguists have suggested loanwords from Austronesian, Tungusic, and Indo-European languages. The most feasible native etymological proposals are Japanese from , (which is where Susanoo discovered the sacred sword), , or ; and , meaning "god; spirit", cognate with the river-dragon. Benedict (1985:167) originally proposed "large snake" was suffixed from Proto-Austro-Japanese *"(w)oröt-i" acquired from Austronesian *"[q]uḷəj" "snake; worm"; which he later (1990:243) modified to *"(u-)orot-i" from *"[q,ʔ]oḷəj". Miller (1987:647) criticized Benedict for overlooking Old Japanese " 'tail' + suffix "-ti" – as well as an obvious Tungus etymology, [Proto-Tungus] *xürgü-či 'the tailed one'", and notes "this apparently well-traveled has now turned up in the speculation of the [Indo-European] folklorists (Littleton 1981)." Littleton's hypothesis involves the 3-headed monster Trisiras or Viśvarūpa, which has a mythological parallel because Indra killed it after giving it soma, wine, and food, but lacks a phonological connection.
Mythological parallels.
Polycephalic or multi-headed animals are rare in biology, but commonly feature in mythology and heraldry. Multi-headed dragons, like the 8-headed Orochi and 3-headed Trisiras above, are a common motif in comparative mythology. For instance, multi-headed dragons in Greek mythology include the 9-headed Lernaean Hydra and the 100-headed Ladon, both slain by Heracles.
Two other Japanese examples derive from Buddhist importations of Indian dragon myths. Benzaiten, the Japanese name of Saraswati, supposedly killed a 5-headed dragon at Enoshima in 552 AD. Kuzuryū (, "9-headed dragon"), deriving from the Nagaraja snake-kings Vasuki and Shesha, is worshipped at Togakushi Shrine in Nagano Prefecture. (Compare the , "nine-headed bird" in Chinese mythology.)
Comparing folklore about polycephalic dragons and serpents, 8-headed creatures are less common than 7- or 9-headed ones. Among Japanese numerals, or () can mean "many; varied" (e.g., , "greengrocer; jack-of-all-trades"). De Visser (1913:150) says the number 8 is "stereotypical" in legends about kings or gods riding dragons or having their carriages drawn by them. The slaying of the dragon is said to be similar to the legends of Cambodia, India, Persia, Western Asia, East Africa, and the Mediterranean area." Smith (1919:215) identifies the mythic 7- or 8-headed dragons with the 7-spiked Pteria spider shell or 8-tentacled octopus.
The myth of a storm god fighting a sea serpent is itself a popular mythic trope potentially originating with the Proto-Indo-European religion and later transmitted into the religions of the ancient Near East most likely initially through interaction with Hittite speaking peoples into Syria and the Fertile Crescent. This motif, known as (German for "struggle against chaos") represents the clash between order and chaos. Often as these myths evolve from their original source, the role of the storm god (himself often the head of a pantheon) is adopted by culture heroes or a personage symbolizing royalty. In many examples, the serpent god is often seen as multi-headed or multi-tailed.
The fight of a hero (sometimes of extraordinary birth) against a dragon who demands the sacrifice of maidens or princesses is a widespread tale. In folkloristics it falls under the Aarne–Thompson–Uther index type ATU 300, "The Dragonslayer".