Tuesday, 22 May 2012

Timekeeper Genes

Timekeeper Gene Regulates Plants’ Body Clocks

 What makes plants have slowed growth in the winter, but flower in the spring? How do plants become active in the day time and inactive at night? These are the sorts of questions that plague scientists from the University of Edinburgh, who have recently shown that the TOC1 protein in plants is the catalyst responsible for slowing their activity at nightfall. This discovery has further enhanced our knowledge of the circadian clocks of plants. Timing of Cab Expression 1 (TOC1) is one of twelve genes that regulate the 24 hour clock controlling the activity of plants.
The twelve gene intricate timing system that governs the studied plants’ systems, as modelled by new computer programming, was revealed to restart the clock at dawn and dusk daily (Millar, 2012). A separate study by Spanish scientists found the same result, verifying the findings. Up until this point, the general scientific consensus was that the TOC1 protein had in fact the opposite effect; they believed it “woke” the plants in the morning. This particular protein is responsible for making genes in the plant work slower when triggered, meaning that during the night the plants use less energy.
Not only does the circadian rhythm control day to day alterations such as reactions due to temperature and sunlight and so on, but it also controls major adaptations in changing seasons. To control gene activity, the body clock of the plants uses negative feedback loops. Negative feedback is a regulatory feature frequently used in biological systems to slow down the production of enzymes. A negative feedback loop works to slow a process by having the output loop back to the beginning and affect an enzyme at the start of the sequence (Reece et al, 2012, p. 10). In plants, the TOC1 interacts with a promoter, CCA1 (Circadian Clock-Associated 1), to inhibit the transcription process, in effect slowing down the processes of the plant. TOC1 forms a larger group of pseudo-response regulators totalling five proteins in all, which all make specific alterations.
This process is extremely complicated, but worth understanding. Circadian clocks affect all biological systems and although they are different in plants and animals, have profound effects on various functions. A few of the main functions this affects are sleep and metabolism. This research is a small step in a much greater search for the knowledge of circadian clocks. It is important to understand these rhythms for a number of reasons. All the factors that affect circadian are not known. Once identified, these factors can then be controlled to influence the maturing of crops and breeding habits of animals in ways that would benefit humans. Having familiarity of how the body clocks of plants run, ought to also highlight when something is wrong and they aren’t running properly. Knowing how body clocks act when they are disrupted is very important when the earth is undergoing rapid climate change, and the understanding of circadian rhythms will give some indication of how plants will be affected by such changes.

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