Job swapping makes its mark on honeybee DNA Switching roles within the hive is reflected in reversible epigenetic changes.by Nicky Guttridge
Excerpt: Gene Robinson… says that although the paper does not necessarily prove that epigenetic mechanisms cause behavioural differences, “it demonstrates for the first time that if behaviour is reversible so is the methylation”.
But Amdam says that the fact that honeybees can revert to a previous role indicates that there is a kind of ‘epigenetic roadmap’. “Brain cells can rely on shifts between these roadmaps to control different behaviours correctly,” she says.
A greater understanding of how epigenetics affects behaviour may lead to insights into human biology, Feinberg says, noting that epigenetic effects on human behaviour might express themselves in addiction, learning and memory. If the link between behaviour and methylation patterns “is true in a bee, it is likely to also be true in us”, he says.
My Comment: Epigenetics can only affect brain-directed behavior by effects on hormones. Moving from the honeybee model organism to vertebrates will be a matter of linking juvenile hormone to luteinizing hormone (LH) secretion that is altered by gonadotropin releasing hormone (GnRH), the biological core of mammalian reproduction. Since the epigenetic effects of nutrient chemicals and pheromones in vertebrates result in changes in intracellular signaling and stochastic gene expression in GnRH neurons; GnRH secretion, and LH secretion, they can be linked to the diversity of genomic interactions that are required in the context of the recently released ENCODE data. However, this is not confabulation!
Gene activation in GnRH neurosecretory neurons of brain tissue in the hypothalamus, for example, links the epigenetic effects of food odors and pheromones to a genetically predisposed and organized GnRH neuronal system and its hormone-driven downstream effects on the development of every other neuronal system linked to differences in behavior via the hypothalamic-pituitary-gonadal and the hypothalamic-pituitary-adrenal axes as is required for the involvement of both the neuroendocrine and neuroimmune systems in behaviors that ensure species survival.
How else are we going to get from the sensory environment to the diversity of its effects on nutrient chemical-driven behavior and pheromone-controlled mammalian reproduction if not via the diversity of nutrient chemical choices that include heterospecific DNA uptake in microbes, and also include species-specific pheromonal regulation of GnRH via the same molecular mechanisms responsible for nutrient-dependent, pheromone-controlled reproduction and speciation of all organisms? The reciprocity of the epigenetically altered vertebrate gene, cell, tissue, organ, organ system pathway is clear, as is its role in adaptive evolution via ecological, social, neurogenic, and socio-cognitive niche construction.
As we’ve now seen in invertebrate species, it is olfaction and odor receptors that provide a clear evolutionary trail that can be followed from unicellular organisms to insects to humans. Of course that trail includes transgenerational epigenetic inheritance of nutrient chemical-dependent and pheromone-controlled behaviors, as these authors have indicated. Kudos to them for moving us forward and away from random mutations theory to an era where geneticists and neuroscientists can examine sensory cause and effect in the proper perspective of an epigenetic continuum of unconscious affects on genomic interactions that already include gene duplication as a mechanism of genomic adaptation for behavior that is required in a changing environment of epigenetic effects.
“The concept that is extended is the epigenetic tweaking of immense gene networks in ‘superorganisms’ (Lockett, Kucharski, & Maleszka, 2012) that ‘solve problems through the exchange and the selective cancellation and modification of signals (Bear, 2004, p. 330)’. It is now clearer how an environmental drive probably evolved from that of food ingestion in unicellular organisms to that of socialization in insects. It is also clear that, in mammals, food odors and pheromones cause changes in hormones such as LH, which has developmental affects on sexual behavior in nutrient-dependent, reproductively fit individuals across species of vertebrates.”
See for review: Kohl, J.V. (2012) Human pheromones and food odors: epigenetic influences on the socioaffective nature of evolved behaviors. Socioaffective Neuroscience & Psychology, 2: 17338. DOI: 10.3402/snp.v2i0.17338.