Expression and Purification of the Melittin Gene from Polistes hebraeus by the GST Gene Fusion System

A cDNA encoding melittin from a wasp (Polistes hebraeus) was amplified and cloned into the GST fusion expression vector pGEX-4T-2. The expressed protein appeared on the SDS-PAGE profiles with an about 29 kDa band. Western blotting proved that the recombinant protein is the fusion protein of GST-PhM. The expression conditions of GST-PhM fusion protein for E. coli BL21 transformant were optimized. Thin layer scanning on the SDS-PAGE profiles showed that the expressed target protein had accumulated up to about 10%～12% of total protein of bacterial cells under the optimized expression condition. Purified and recovered recombinant melittin of Polistes hebraeus showed bioactivity in activating rabbit platelets to aggregate.

Ultrastructural features of the hypopharyngeal glands in the social wasp Polistes versicolor （Hymenoptera： Vespidae）

The wasps of the genus Polistes have been considered the key to understanding the evolution of social behavior in Hymenoptera. Several studies have shown that the development of organized insect societies was accompanied by the evolution of structures like exocrine glands, which became specialized to perform specific functions. This article investigates the ultrastructural and cytochemical features of the hypopharyngeal glands of Polistes versicolor. These glands have been studied in depth in social bees, where they occur only in nurses and produce the royal jelly. Our results＇ revealed that these glands basically did not vary among individuals or between sexes. They are constituted by spherical cells, each with a large nucleus and well-developed rough endoplasmic reticulum. Secretion vesicles are abundant, but lipid droplets were not observed, indicating that these glands may not have a role in pheromone synthesis. Acid phosphatase was detected in lysosomes, and also flee in the cytosol, but did not seem to be related with cell death. Thus, our results suggest that the hypopharyngeal glands ofP. versicolor may not have a specialized social role, but could produce digestive enzymes.

Evolutionary consequences of deception： Complexity and informational content of colony signature are favored by social parasitism

Nestmate recognition codes show remarkable chemical complexity, involving multiple biochemical pathways. This complexity provides the opportunity to evaluate the ecological and social conditions that favor the evolution of complex signaling. We investigated how the chemical signatures of three populations of the social paper wasp Polistes biglumis differed in terms of concentration of hydrocarbons, proportions of branched hydrocarbons and overall variation. We tested whether the variation in chemical signatures among populations could be explained by the prevalence of social parasites or whether this was just an effect of local abiotic conditions which influenced the composition of the hydrocarbon cuticular layer. We studied the chemical signa- ture in three populations in which obligate social parasites differed in the selection pressures they imposed on host populations. Within each population, we restricted our analyses to non-parasitized hosts, to avoid potential short-term effects of parasite pres- ence on the host chemical signatures. We found that host colonies in parasitized populations had more diverse profiles than the parasite-free population. Moreover, the overall concentration of hydrocarbons and the relative proportion of branched hydrocar- bons were larger in the parasitized populations, relative to the non-parasitized one. This is to our knowledge the first evidence in favour of the hypothesis that different traits in the host chemical signatures as a whole undergo evolutionary changes resulting from directional or balancing selection imposed by social parasites. We conclude that obligate social parasites act as ＇engines of diversity＇ on host chemical signatures and operate in favor of a geographic mosaic of diverging communication codes