Sleep-Wake Cycles: Magnanimity of Magnesium

All of us know how the sleep-wake cycles work in us: behind our eyes, just below where the optic nerve from the eyes cross, there is the pituitary gland that has melatonin which increases and decreases in response to light and makes us sleepy or awake. Right?

Wrong. Circadian rhythms are found even in plants that do not have eyes or pituitary. Circa means about, dian refers to day. The clock that is inbuilt in living creatures has fascinated biologists and in the last few years we have seen discoveries of a large number of clock genes. So it is not the nervous system that is responsible for the daily cycles, but the clock genes, right?

Wrong. Says a paper in yesterday's Nature. Behind the evolution of clock genes, behind the evolution of pituitary, is the magic of magnesium.

The daily pendulum of human and algal cells, separated by more than a billion years of evolution, swing in response to intracellular magnesium. The element is needed in modest and meagre amounts, and is critical for life: magnesium is a cofactor in all ATP dependent processes. In other words, metabolic energy yo-yos with magnesium. And that sets the pattern for the evolution of clock genes, the evolution of the nervous system with a pituitary that releases melatonin...

The magnanimity of the modest magnesium!

Nature 532, 375–379 (21 April 2016)

Risk Takers Turn Risk Aversive:

We do not normally take risks. Yet, at times, we do. Scientists in Stanford University tell us why, in the recent issue of Nature. They have succeeded in turning risk taking rats into risk aversive ones by timely stimulation of dopamine type 2 receptors in some specific cells of the Nucleus accumbens.

The nucleus accumbens is generally considered the reward centre in the brain and is implicated in addiction. But given the results that are pouring in about the nucleus, perhaps it is more involved in decision making than in addiction.

Nature 531,642–646 (31 March 2016)