Lambda Repressor. The repressor molecule of the Lambda bacteriophage binds not only to the OR1 site to prevent Cro transcription, but also to OR2, where it aids the binding of RNA polymerase to the repressor promoter. In fact a repressor dimer bound to OR1 interacts cooperatively with a second dimer binding to OR2.
Mandevillas grow as tropical perennials in frost-free regions. When looking for an attractive, blooming tropical vine, don't overlook mandevillas (Mandevilla spp.). These lovely climbing vines have abundant and showy blossoms that are produced for a period of several months.n these areas, mandevilla vines can reach a height of 10 to 20 feet, with older stems becoming woody and thick. In parts of zone 8 where winter frosts might occur, mandevillas planted outdoors often die back to the ground but regrow from surviving roots the next spring.
Desert senna (Senna covesii) and Coulter hibiscus (Hibiscus coulteri) flower in response to any warm rain and peak in summer when most such rain occurs. Desert zinnia (Zinnia pumila) is truly biseasonal, flowering well in both rainy seasons. Cacti. Cacti include several summer-flowering species.