What has colour fluctuation in certain leaves got to do with the change of seasons? More than meets the eye and mind. The changes are collectively called biological rhythms — or, behavioural changes that may not be just passive responses to environmental variations. Such changes are driven by ‘endogenous oscillators,’ called biological clocks, or chronometers, located within all living organisms. The pre-eminent facet also is they are smart and highly adaptive.
The existence of the biological clock was first demonstrated by Hans Kalmus and Erwin Bunning in 1935. Their study revealed that there existed a solitary master circadian [circa = about; dies = day] clock, in human beings and all living beings, coupled to a series of ‘subordinate oscillators.’ The fact also is — the pineal gland and its hormone, melatonin, are requisite to maintain the normal phase and amplitude of our different body rhythms, their synchronisation with one another, besides the external environment.
Melatonin is a chemical messenger. It functions as a chronobiotic substance — one having the capacity of resetting desynchronised body rhythms back to normal by permeating through every cell and tissue. One outstanding example of the mechanism is ‘jet-lag,’ which is the inability of the air traveller to resynchronise their body rhythms with the time of their destination. The role of specific nuclei of the hypothalamus is just as important in the context. The nuclei, connected by nervous pathways to the eyes and pineal gland, act as circadian time-keepers — to help our biological clocks keep ticking on ‘auto-pilot,’ as it were.
There’s more to the biological clock than melatonin. When scientists first stumbled upon the plant gene, cab, they found that it was not stimulated by any external factor — sunlight, for instance. It appeared that the gene was activated by the plant’s own internal clock, which ticked without being in any way dependent on its local milieu. The ball was, thus, set rolling.
Our biological clocks’ overall functioning is captivating — this is evident through the process of sleep-wake-wake-sleep-cycle, which, in turn, is closely associated with such fascinating mechanisms as regulation of body temperature, tolerance to pain, sensitivity to drugs, hormonal levels, a variety of emotional deviations at the time of new, or full moon nights — on the basis of which doctors prescribe certain drugs — and, so on. These functions rise and fall with a sort of computerised regularity attuned as they are to the finer mechanics of a ‘natural balance,’ which is just apt and delicate. So fragile is this equilibrium that a clock that goes kaput, not only in its wake-sleep cycle, but also by way of its full day-night pattern, may lead to symptoms of depression. A similar drama takes place in plants in the form of leaves that rise and fall, petals that open and close — of functions that cover chemical changes like the cab gene formation, the process of photosynthesis and reproduction, aside from the mechanism of flowering.
What drives our biological clock was a mystery, right from the time of Aristotle. With the development of science, it was realised that solar energy was not a requirement — the most basic need at that, or so was deduced — for our life. Or, was, likewise, thought by our ancient philosophers — and, that most biological rhythms and events could go on without the sun ‘smiling’ at us.
While the cab gene has become one of the most indispensable components in the running of the biological clock, it is still not considered the ‘key’ in the entire mechanism. The removal of this simple ‘on-off’ switch, for instance, does not make time stand still. When switched off, it may, at best, stop the cab protein, for example, from being formed. This is also one reason why ‘bioclock’ researchers accept the existence of three, or more, different genes which may have a say in the running of our biological clock — independently, or conjointly.
When plant researchers identified a gene, per, in fruit flies, they felt happily ‘hijacked’ to the seventh heaven of science. Reality dawned upon them, soon enough, when they learned that mutations could also cause the biological clock to run haphazardly, go slow, speed up, or lose its sense of time. There was hapless ‘comfort’ too when it was also realised that a central gene like cab, which when mutated, could only knock off one function while allowing the biological clock to run by controlling certain unconnected rhythms.
Plant geneticists have been fascinated, no less, with the tobacco plant, although their line of thought signifies cautious optimism. When they placed — and, this is how it all began — a luciferase gene into the smoker’s plant, they saw a glow. The gene apparently emitted light. Propped by the result, they embarked on making use of the gene and encouraging plants to gleam once in a day like the flash-gun in a camera.
New exciting research suggests that the build-up of oxygen in the atmosphere, 2.5 billion years ago, may have possibly determined the evolution of our circadian rhythms. What’s more, science has recently identified a protein, which has the ‘bandwidth’ to be a strong marker of circadian rhythms, albeit one may not be just as certain as to what explicitly causes natural bio-rhythms to take place.
What adds substance is a novel prospect. When a research team from South Korea stumbled upon and identified the new gene responsible for sustaining our internal biological clock — in a collaborative project with Northwestern University, US — and, experimented with transformed small fruit flies, they found there was an undiscovered gene that ‘deals’ with bio-rhythms in the brain and acts as a sub-atomic biological clock, while regulating the rhythm of life of each cell. This landmark finding is an innovation by itself. It has laid the groundwork to ‘decrypting’ the precise role of the protein produced by the gene in the working of our biological clock.
— First published in The Himalayan Times, Nepal
