Textbook knowledge and “canonical” biochemical pathways

Name That Metabolite!

A guided tour through the metabolome

Excerpt: “4. WHAT IF I CAN’T IDENTIFY A METABOLITE?

Join the club. Few metabolites in metabolomics data sets correspond to the “canonical” biochemical pathways found in textbooks, Patti says, and many have never been seen before. This, combined with the fact that metabolites, unlike proteins, do not assemble from a small number of known and easily differentiated building blocks, means researchers can rarely name every molecule they see.”

My comment: Obviously, this is a problem for anyone willing to attempt to isolate a nutrient-dependent human pheromone (i.e., a molecule from a mixture of species-specific pheromones: the metabolites of nutrients that control reproduction in species from microbes to man). However, pheromones have been isolated in some species, which means that despite our omnivorous diet and the complexities of our microbe-dependent metabolome, someone will isolate a human pheromone from a mixture like the androstenol/androsterone mixture that appears to epigenetically affect women’s behavior. This should happen soon.

From the time the term pheromones was defined in 1959, it took until earlier this year to find extraordinary proof of a moth pheromone that controls reproduction. However, some advances like this have been quickly made because they are based on what has been learned about molecular epigenetics and conserved molecular mechanisms across species.

Unfortunately, even though we know that the molecular mechanisms of pheromone production are nutrient-dependent in species from microbes to man, this moth pheromone reportedly resulted from a “mutation.”  That misrepresentation of cause and effect might lead some people to believe that pheromonal communication in ~ 180 000 species of moth and butterfly in the world is due to ~180,000 different mutations. They are likely to think that mutations resulted in species-specific changes in pheromones, because small differences in different moth ‘scents’ enable the males to find females of their own species. In the case reported, it was a small difference caused by substitution of one critical amino acid. How did this substitution become misrepresented as if it were a mutation? I don’t know.

However, I know this erroneous report of mutational cause can be placed into the perspective of Darwin’s ‘conditions of life.‘ Indeed, we can be sure that the adaptive evolution of each species required nutrients — food to sustain life (sans mutations). We can also be sure that the metabolism of nutrients to pheromones, which control reproduction, occurred sans mutations so that the existing supply of nutrients was not exhausted by mutants.

Besides, placed into the context above, a species of mutant moths could not survive if members of the species could not identify each other as nutrient-dependent reproductively fit conspecifics. Thus, if a mutation caused the reported substitution of one critical amino acid, the mutation would also have had to simultaneously occur in both males and females of the species so that they could identify a reproductively fit mate. However, the sex differences in the moths that enable them to recognize the difference between males and females also would have had to be physiologically effected by the mutation.  (The mutation would have to cause sex differences in hormone-dependent organization and activation of behavior).

The entirety of the mutation-driven scenario involving substitution of one critical amino acid seems unlikely, but even more so due to examples in other species that link nutrients, but not mutations, to differences in pheromone production. I’ve detailed those examples in a recent review, and included one from additional studies at Harvard that report their findings in vague terms of mutation-driven evolution in a human population.

My review includes a detailed model of epigenetic effects. The changes in the human population, which are associated with the change in physical features that are species-specific and sexually selected , are nutrient-dependent and pheromone-controlled. That’s consistent with what we have learned from examples of across species comparisons. Mutations theory is not!

See also: Microbes can influence evolution of their hosts. To demonstrate this in invertebrates (i.e., insects), they used three species of Nasonia (wasps). Their results clearly indicate that the microbiome influences adaptive evolution sans random mutations via the microbial metabolism of nutrients to pheromones that control reproduction — as noted in Nutrient-dependent/pheromone-controlled adaptive evolution: a model with the following citation: Niehuis, O., Buellesbach, J., Gibson, J. D., Pothmann, D., Hanner, C., Mutti, N. S., et al. (2013). Behavioural and genetic analyses of Nasonia shed light on the evolution of sex pheromones. Nature, 494, 345–348.