In examining several different histone modifications, the team found a number of distinct differences between the major and minor castes. Simola states that the most notable modification, "both discriminates the two castes from each other and correlates well with the expression levels of different genes between the castes. And if you look at which genes are being expressed between these two castes, these genes correspond very nicely to the brainy versus brawny idea. In the majors we find that genes that are involved in muscle development are expressed at a higher level, whereas in the minors, many genes involved in brain development and neurotransmission are expressed at a higher level."
These changes in histone modifications between ant castes are likely caused by a regulator gene, called CBP, that has "already been implicated in aspects of learning and behavior by genetic studies in mice and in certain human diseases," Berger says. "The idea is that the same CBP regulator and histone modification are involved in a learned behavior in ants foraging mainly in the brainy minor caste, to establish a pattern of gene regulation that leads to neuronal patterning for figuring out where food is and being able to bring the food back to the nest."
Simola notes that "we know from mouse studies that if you inactivate or delete the CBP regulator, it actually leads to significant learning deficits in addition to craniofacial muscular malformations. So from mammalian studies, it's clear this is an important protein involved in learning and memory."
These findings have established the crucial role of genome structure in general, and histone modifications in particular, in determining the acquisition of organism-level characteristics i
|Contact: Karen Kreeger|
University of Pennsylvania School of Medicine