Social evolution. Genomic signatures of evolutionary transitions from solitary to group living.

The evolution of eusociality is one of the major transitions in evolution, but the underlying genomic changes are unknown. We compared the genomes of 10 bee species that vary in social complexity, representing multiple independent transitions in social evolution, and report three major findings. First, many important genes show evidence of neutral evolution as a consequence of relaxed selection with increasing social complexity.

Exoskeleton formation in Apis mellifera: cuticular hydrocarbons profiles and expression of desaturase and elongase genes during pupal and adult development.

Cuticular hydrocarbons (CHCs) are abundant in the superficial cuticular layer (envelope) of insects where they play roles as structural, anti-desiccation and semiochemical compounds. Many studies have investigated the CHC composition in the adult insects. However, studies on the profiles of these compounds during cuticle formation and differentiation are scarce and restrict to specific stages of a few insect species.

Dicer-1 is a key enzyme in the regulation of oogenesis in panoistic ovaries.

Background Information: In insects, the action of microRNAs (miRNAs) on oogenesis has been explored only in dipterans, which possess meroistic ovaries, a highly modified ovarian type. Here we study miRNA function in the most primitive, panoistic type of ovaries using the phylogenetically basal insect Blattella germanica (Dictyoptera, Blattellidae) as model.

Results: Dicer-1 (Dcr1), a key enzyme in miRNA biogenesis, was depleted using RNAi.

Sequence and expression pattern of the germ line marker vasa in honey bees and stingless bees.

Queens and workers of social insects differ in the rates of egg laying. Using genomic information we determined the sequence of vasa, a highly conserved gene specific to the germ line of metazoans, for the honey bee and four stingless bees. The vasa sequence of social bees differed from that of other insects in two motifs.

Expression analysis of putative vitellogenin and lipophorin receptors in honey bee (Apis mellifera L.) queens and workers.

Two members of the low density lipoprotein receptor (LDLR) family were identified as putative orthologs for a vitellogenin receptor (Amvgr) and a lipophorin receptor (Amlpr) in the Apis mellifera genome. Both receptor sequences have the structural motifs characteristic of LDLR family members and show a high degree of similarity with sequences of other insects. RT-PCR analysis of Amvgr and Amlpr expression detected the presence of both transcripts in different tissues of adult female (ovary, fat body, midgut, head and specifically hypopharyngeal gland), as well as in embryos.