The discovery of the circadian photoreceptor Assignment

The discovery of the circadian photoreceptor - Assignment Example mid-1990s to the discovery of a new molecule known as the Cryptochrome that showed a close relation to photolyases in the bacteria cells (Nicolas and Sassone-Corsi, 60). Cryptochrome genes cry1 and cry2 coded for universal proteins, CRY 1 and CRY 2 found in almost all the kingdoms of the living organisms (Nicolas and Sassone-Corsi, 60). These proteins activated the light sensitive cofactors and cells that make the photoreceptor cells to detect light in rhythmic manner. They also act as DNA repair enzymes in case of any damage from light related radiations such as the UV light (Robert , Lucas et al, 505). The unearthing of the molecules would then give clue to the discovery of the cells of the circadian photoreceptors. Consequently, this followed the exhumation of most of the photoreceptive cells that respond to the 24- hour clock in the first quarter of 1900s (Martha , Spoelstra and Roenneberg, 931). These special cells, found to be containing a pigment known as melanopsin, would lat er acquire different names including intrinsically photosensitive Retinal Ganglion Cells (ipRGC) (Howard, Herbin and Nevo, 156). This was many decades later after the discovery of the rods and cons in the mammalian eye, making the ipRGC a new element at the time. Much of the changes in the findings into these cells did not accrue until around the year 1990s, the same time that research on the circadian molecules was very active. However slow in their activities, they were solely responsible for the change in the rhythmic day and light cycles (Martha , Spoelstra and Roenneberg, 932). In addition, the pigments have recently been active even without the presence of cones and rods thereby helping the individual to detect the slightest changes of light and darkness. Actually, the detection of... The discovery of the circadian photoreceptor The gene coding for these photoreceptors were detected by breeding of bean plant under two different conditions, of long periods and short periods. Unfortunately, the light and dark periods were not considered, therefore the experiment would prove disastrous to deal with especially in conducting the genetic analysis. Following a long struggle over many decades’ scientists in due course were able to detect some of the genes responsible for coding of these circadian rhythmic proteins. At around 1970s, the knowledge of mutagenesis would act as the focal point to the first discovery of these genes, which later would attain the name ‘clock genes’ in the Drosophila melanogaster fly.This improved the prospects of the eventual discovery of the photoreceptor cells and their molecular make up. Later on, there was an increase in the discovery of many other genes coding for the circadian rhythm from several plant as well as animal families. At around 1980s, scientists discove red a gene called HY4 that they thought was solely responsible for the blue light detection in Arabidopsis thaliana plant. More experiments conducted found out its homology in mammals and their effects attributed to the functions of photolyases. The discovery towards circadian photoreceptor proved to be challenging and deceptive over a long period. Scientists would stumble at many molecules and pigments such as the HY4 genes and the cones and rods before coming into the right conclusions. Earlier on, the cones and rods were thought to be the only cells in control for the photo-transduction in the retina of the eye.