Changes in vitellogenin expression caused by nematodal and fungal infections in insects

This study examined the expression and role of vitellogenin (Vg) in the body of the firebug (Heteroptera, Insecta) during infection elicited by two entomopathogenic organisms, the nematode and the fungus Infection by significantly upregulated mRNA expression in the male body. The corresponding increase in Vg protein expression was also confirmed by electrophoretic and immunoblotting analyses. Remarkably, in females, the opposite tendency was noted. Nematodal infection significantly reduced both mRNA and Vg protein expression levels in fat body and hemolymph, respectively. We speculate that infection of reproductive females reduces Vg expression to a level that is still sufficient for defense, but is insufficient for reproduction. This circumstance reduces energy expenditure and helps the individual to cope with the infection. Importantly, purified Vg significantly inhibited growth of spp., an entomotoxic bacteria isolated from However, the effect of Vg against was not so obvious. The fungus significantly stimulated gene expression in males; however, a similar increase was not recapitulated at the protein level. Nevertheless, in females, both mRNA and protein Vg levels were significantly reduced after the fungal infection. The obtained data demonstrate that Vg is probably an important defense protein, possibly with a specific activity. This considerably expands the known spectrum of Vg functions, as its primary role was thought to be limited to regulating egg development in the female body.