Thursday, January 10, 2008

Is nitric oxide an archaic communication signal?

Do you think of our primordial language? or, not even a language just an initial communication system…in those early days with groups of cells launching the transition from unicellular to multicellular organisms ~ a giga years ago…
Contemplating for a long time on the nitric oxide (NO) netting system, has led me to suggest that maybe it was compounds like NO which enabled such initial communication. The advantage of a radical NO net as a communication tool is its simplicity and availability, and its drawback is its vulnerability and reactivity.
What triggered this blog was the study published by the Geobiology Research Group of the Virginia Tech. They have discussed the 2 explosive evolutionary events which shaped the early history of multicellular life, and I thought whether it was gases like NO or CO which enabled the communication and organization of multicellularity. Such compounds are major signals at our times and they were even more predominant in the prehistoric days when life forms were simpler and less diverse.
The presence and functions of NO in the animal, vegetative or microbial kingdoms are well documented. In an historical review, it was shown that NO is indeed an archaic molecule, biologically functioning in every living organism. It is not difficult to understand its abundance and essentiality, especially prior to the evolution of the biological nitrogen fixation. Nitrogen is an essential element for life and is often a limiting nutrient. As most nitrogen is locked in the stable form, N2, in the atmosphere, processes that can fix N2 into biologically available forms control the supply of nitrogen for organisms. On the early Earth, nitrogen is thought to have been fixed abiotically, as NO was formed during lightning discharge.
In a recent study, the functions of NO in the developing circulatory system were expanded, NO is also important for vessel formation and tone.
While discussing these issues with Prof. Xiao from the Virginia Tech, he has suggested that the modern analogs for the early multicellular organisms would be sponges and cnidarians, and I guess it would be very illuminating to study the effects of NO on their social behavior. Any suggestions?
If indeed the NO net is so ancient, it was functioning before the evolution of the brain and senses. This opens a novel point of view for a current communication system, operating unrelated to emotions or mind, pls read the Viagra blog. Is it part of what we attribute to alternative communication routes? mysticism? holism?

On nitric oxide signaling, metamorphosis, and the evolution of biphasic life cycles
Evol Dev., 2003 Sep-Oct;5(5):542-50

A hypothesis about cellular signaling with nitric oxide in the earliest life forms in evolution
Free Radic Biol Med. 2009 May 9.