Turkeys: Differential gene expression is nutrient-dependent
November 28, 2013 | James Kohl
Happy Thanksgiving from folks at “The Scientist” who thought it was cute to again note comments from Nov 1, about a nutrient source some of us may consume today, Nov 28.
Differential gene expression between dominant and subordinate male turkeys could help evolutionary biologists deconstruct the roots of sexual dimorphism.
By Tracy Vence | November 1, 2013
Excerpt: “This is a great example of how differences among individuals are not exclusively determined by differences in DNA sequence,” says Alan Krakauer, a biologist at the University of California, Davis, who was not involved in the work. “Behavior and the social environment are probably responsible for the transcriptome differences they found. It’s not all ‘inside, out’—there’s a lot of feedback between what’s going on outside the organism and what’s going on under the skin.”
My comment: At the evolutionary advent of sexual reproduction in yeasts, increased nutrient uptake determines “male” morphogenesis and the pheromone-controlled physiology of reproduction. See for example: Signaling Crosstalk: Integrating Nutrient Availability and Sex and our 1996 review for information on the molecular epigenetics of sexual orientation and sex differences in behavior.
“Molecular epigenetics” Yet another kind of epigenetic imprinting occurs in species as diverse as yeast, Drosophila, mice, and humans and is based upon small DNA-binding proteins called “chromo domain” proteins, e.g., polycomb. These proteins affect chromatin structure, often in telomeric regions, and thereby affect transcription and silencing of various genes…. Small intranuclear proteins also participate in generating alternative splicing techniques of pre-mRNA and, by this mechanism, contribute to sexual differentiation in at least two species, Drosophila melanogaster and Caenorhabditis elegans… That similar proteins perform functions in humans suggests the possibility that some human sex differences may arise from alternative splicings of otherwise identical genes.”
The molecular mechanisms of sex determination via nutrient-dependent alternative splicings do not change in species from microbes to man, which means that sexual dimorphism is also nutrient-dependent and pheromone-controlled (See Bird odour predicts reproductive success) in turkeys.