Review Article – Article Example
Circadian photoreceptors- cells and molecules Brief summary The 1998 article by Yasuhide Miyamoto and Aziz Sancar discusses circadian rhythm with a special focus on photoreceptors. It reviews the day light – dark cycles in all living organisms from bacteria to mammals with emphasis on the latter. It looks at studies that have been made to advance the understanding of clock genes, that respond to light and establishes their molecular basis in circadian rhythm. Studies have revealed that the light –responsive genes in question have a 24 hour interlude for oscillatory transcription with auto-regulatory loops. Two blue light -light photoreceptors known as cryptochromes 1 and 2(CRY1 and CRY2) discovered in mammals have been closely studied in the article to shed more light into the circadian rhythm (Miyamoto and Aziz, Pg 1). To provide evidence to this, a Northern blot analysis has been undertaken to with mCRY1 and mCRY2mRNA from diverse tissues subjected to laboratory processes.
From the lab process, a conclusion is drawn that cryptochromes are circadian rhythm (clock) photoreceptors in mammals in as much as the result is regarded as provisional due to the absence of mammalian cryptochrome that shows sign of envisaged circadian rhythm defects.
The article content corresponds with its title given the pre-Northern blot analysis, the lab process and conclusions drawn thereafter. It samples tissues from diverse mammalian organs to test the circadian rhythm phenomenon and therefore, lives up to its heading.
The goal of this work is to establish that photic entrainment is exhibited by mammals that have a visual impairment and those that do not. Knowledge of the existence of a photoactive pigment in the nonrod noncone has been instrumental in meeting this objective.
The authors have identified, from the lab report in the Northern blot analysis that photoactive pigment is the mammalian homolog of the cryptochrome in plants that are blue light photoreceptors.
1. Can it therefore, be concluded that circadian rhythm in mammals is similar to that of plants?
2. Does visual impairment play no role whatsoever in circadian rhythm and that this clock works in visually capable mammals in similar ways as the incapable?
Miyamoto , Yasuhide , and Aziz Sancar. "Vitamin B2-based blue-light photoreceptors in the retinohypothalamic tract as the photoactive pigments for setting the circadian clock in mammals". Proceedings of the National Academy of Sciences . N.p., 9 Mar. 1998. Web. 11 Mar. 2013. .