Project description:Our aims in this study were: 1) to identify the miRNAs of the bumble bees Bombus terrestris and B. impatiens; 2) to compare the total numbers of miRNAs between both bumble bee species and between them and the honey bee, Apis mellifera; and 3) to test whether the sequences and expression patterns of miRNAs were conserved between species. To investigate each of these aims we used miRNA-seq (deep sequencing of miRNA-enriched libraries) in B. terrestris, and bioinformatics prediction programs to identify miRNAs in both Bombus species. We identified 131 miRNAs in B. terrestris, and 114 in B. impatiens; of these, 17 were new miRNAs that had not previously been sequenced in any species. We found a striking level of difference in the miRNAs present between Bombus and A. mellifera, with 103 miRNAs in A. mellifera not being present in the genomes of the two bumble bees. miRNA profiles of Bombus terrestris at two developmental stages in larvae. This submission represents 'Bombus terrestris' component of study.
Project description:During the nest-founding phase of the bumble bee colony cycle, queens undergo striking changes in maternal care behavior. Early in the founding phase, prior to the emergence of workers in the nest, queens are reproductive and also provision and feed their offspring. However, later in the founding phase, queens cease feeding offspring and become specialized on reproduction. This transition is synchronized with the emergence of workers in the colony, who assume the task of feeding their siblings. Using a social manipulation experiment, we tested the hypothesis that workers socially regulate the transition from feeding brood to specialization on reproduction in nest-founding bumble bee queens. Consistent with this hypothesis, we found that early-stage queens with workers prematurely added to their nests reduce their brood-feeding behavior and increase egg-laying, and likewise, late-stage queens increase their brood-feeding behavior and decrease egg-laying when workers are removed from their nests. Further, brood-feeding and egg-laying behavior were negatively correlated in these queens. We used an Agilent brain EST-based microarray to explore a second hypothesis, that workers alter brain gene expression in nest-founding queens. We found evidence that brain gene expression in nest-founding queens is altered by the presence of workers, with the effect much stronger in late-stage founding queens. Additionally, expression levels of some genes were correlated with quantitative differences in brood-feeding and egg-laying behavior. This study provides new insights into how the transition from feeding brood to specialization on reproduction in bumble bee queens is regulated during the nest initiation phase of the colony cycle.