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. By RT-PCR we confirmed the germ line specificity of Amvasa expression in honey bees. In situ hybridization on ovarioles showed that Amvasa is expressed throughout the germarium, except for the transition zone beneath the terminal filament. A diffuse vasa signal was also seen in terminal filaments suggesting the presence of germ line cells. Oocytes showed elevated levels of Amvasa transcripts in the lower germarium and after follicles became segregated. In previtellogenic follicles, Amvasa transcription was detected in the trophocytes, which appear to supply its mRNA to the growing oocyte. A similar picture was obtained for ovarioles of the stingless bee Melipona quadrifasciata, except that Amvasa expression was higher in the oocytes of previtellogenic follicles. The social bees differ in this respect from Drosophila, the model system for insect oogenesis, suggesting that changes in the sequence and expression pattern of vasa may have occurred during social evolution

Host-Microbe Interactions in the ChemosyntheticRiftiapachyptilaSymbiosis

The deep-sea tubewormRiftia pachyptilalacks a digestive system butcompletely relies on bacterial endosymbionts for nutrition. Although the symbionthas been studied in detail on the molecular level, such analyses were unavailable forthe animal host, because sequence information was lacking. To identify host-symbiont interaction mechanisms, we therefore sequenced theRiftiatranscriptome,which served as a basis for comparative metaproteomic analyses of symbiont-containing versus symbiont-free tissues, both under energy-rich and energy-limitedconditions. Our results suggest that metabolic interactions include nutrient alloca-tion from symbiont to host by symbiont digestion and substrate transfer to the sym-biont by abundant host proteins. We furthermore propose thatRiftiamaintains itssymbiont by protecting the bacteria from oxidative damage while also exerting sym-biont population control. Eukaryote-like symbiont proteins might facilitate intracellu-lar symbiont persistence. Energy limitation apparently leads to reduced symbiontbiomass and increased symbiont digestion. Our study provides unprecedented in-sights into host-microbe interactions that shape this highly efficient symbiosis