Behavioral plasticity involves changes in adult brain function, some of which require changes in gene expression. In honey bees (Apis mellifera), the age-related transition of adult workers from hive work to foraging was associated with changes in mRNA abundance in the brain for more than one-third of genes tested, out of approximately 5500, as determined using bee brain microarrays and statistical analyses (ANOVA and Bayesian). To understand whether these changes were related to behavioral state or advancing age, colony social environment was manipulated to uncouple behavior and age. Clustering and principal component analyses of gene expression in age-matched hive bees and foragers revealed that mRNA changes were primarily associated with behavior rather than age. Using "leave-one-out" cross-validated class prediction, mRNA levels in single dissected brains predicted behavior for 57 out of 60 individual bees tested, indicating that gene expression profiles in individual brains robustly reflected individual behavioral state. Many gene expression differences that were statistically significant and highly predictive of individual behavior were of low magnitude (i.e., less than 3-fold different between hive bee and forager brains on average). Genes that were most "predictive" of individual behavior included putative components of MAP kinase and IP3/DAG signal transduction pathways, genes involved in neurotransmitter secretion and axonogenesis, and several transcription factors. Behavioral plasticity may thus involve wide-spread genomic plasticity in the brain, although gene expression changes may be subtle.
Species 1: Hymenoptera Apidae Apis mellifera (honey bee)
Keywords: neurobiology, caste
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