Ant intelligence; chemical controls (Introduction)

by David Turell , Saturday, January 02, 2016, 01:06 (3038 days ago) @ dhw

Individual ants can be re-programed by chemical epigenetic changes to change their role in the societal setup:-http://phys.org/news/2015-12-team-reprograms-social-behavior-carpenter.html-"In a previous study, the authors created the first genome-wide epigenetic maps in ants. This revealed that epigenetic regulation is key to distinguishing majors as the "brawny" soldiers of carpenter ant colonies, compared to minors, their smaller, "brainier" sisters. Major ants have large heads and powerful mandibles that help to defeat enemies and process and transport large food items. Minor ants are much smaller, outnumber majors two to one, and assume the important responsibility of searching for food and recruiting other ants to help with the harvest. Compared to majors, these foraging minors have genes involved in brain development and neurotransmission that are over expressed.-"In the new findings, an interdisciplinary research team led by senior author Shelley Berger, PhD, from the Perelman School of Medicine at the University of Pennsylvania, in collaboration with teams led by Juergen Liebig from Arizona State University and Danny Reinberg from New York University, found that caste-specific foraging behavior can be directly altered, by changing the balance of epigenetic chemicals called acetyl groups attached to histone protein complexes, around which DNA strands are wrapped in a cell nucleus. To reveal this exquisite control, the team demonstrated that foraging behavior could be reprogrammed using compounds that inhibit the addition or removal of these acetyl groups on histones (histone acetylation), in turn changing the expression of nearby genes.-***-"Ants, as well as termites, and some bees and wasps, are eusocial (or "truly social") species. Previous work suggested that histone acetylation could create dramatic differences in gene expression between genetically identical individuals, contributing to the physical differences in body size and reproductive ability between ant castes-***-"In contrast to the dramatic boost in foraging seen in minors, feeding mature major workers these inhibitors caused little to no increase in foraging. However, the team found that directly injecting these epigenetic inhibitors into the brains of very young majors immediately increased foraging, reaching levels normally only observed in minors. Additionally, a single treatment with these inhibitors was sufficient to induce and sustain minor-like foraging in the majors for up to 50 days. These results suggest that there is an "epigenetic window of vulnerability" in young ant brains, which confers increased susceptibility to environmental manipulations, such as with histone-modifying inhibitors.-***-"One important gene implicated in the ant study is CBP, which is an epigenetic "writer" enzyme that alters chromatin by adding acetyl groups to histones. CBP had already been implicated as a critical enzyme facilitating learning and memory in mice and is mutated in certain human cognitive disorders, notably Rubinstein-Taybi syndrome. Hence, the team's findings suggest that CBP-mediated histone acetylation may also facilitate complex social interactions found in vertebrate species.-"The authors suspect that CBP's role as an epigenetic writer enzyme contributes to patterns of histone acetylation that enhance memory pathways related to learned behaviors such as foraging. Differences in CBP activity between minor and major castes may guide unique patterns of gene expression that fine tune neuronal functions for each caste."-Comment: I suspect the colony automatically senses the need to change population dynamics and these chemical changes are also automatic at that point. Note the CBP is an enzyme. Enzymes are giant molecules which raise the issue of 'how did that evolve'?