Genes encoding putative Takeout/juvenile hormone binding proteins in the honeybee (Apis mellifera) and modulation by age and juvenile hormone of the takeout-like gene GB19811

We identified and characterized eight genes encoding putative Takeout/juvenile hormone binding proteins (To/JHBP) in the honeybee genome. Phylogenetic analyses revealed nine distinct lineages within this gene family, including those containing Takeout (To) and JHBP for which there are no honeybee homologs. Their diversity and ubiquitous expression suggest that To/JHBP proteins are involved in diverse and important processes in insects. We further characterized the expression of one of these genes, GB19811 that is ubiquitously expressed. GB19811 transcript levels in the abdomen increased, and decreased in the head with worker age. There was no influence of colony environment or brood care behavior on GB19811 expression in young bees. Young bees treated with juvenile hormone (JH) showed a decrease in head GB19811 mRNA levels. This finding is consistent with the premise that JH, for which titers typically increase with age, is involved in age-related modulation of GB19811 expression. In contrast to Drosophila Takeout, the expression of GB19811 did not vary with diurnal or circadian rhythms. Taken together, these findings suggest that GB19811 is not an ortholog of Takeout, and is involved in JH-mediated regulation of adult honeybee worker development.