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

Abstract

This study examined the expression and role of vitellogenin (Vg) in the body of the firebug Pyrrhocoris apterus (Heteroptera, Insecta) during infection elicited by two entomopathogenic organisms, the nematode Steinernema carpocapsae and the fungus Isaria fumosorosea. Infection by S. carpocapsae significantly upregulated Vg 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 Vg 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 Xenorhabdus spp., an entomotoxic bacteria isolated from S. carpocapsae. However, the effect of Vg against I. fumosorosea was not so obvious. The fungus significantly stimulated Vg 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.

Seasonality in telomerase activity in relation to cell size, DNA replication, and nutrients in the fat body of Apis mellifera

“…Vg is synthesized in the fat body and accumulates in hemolymph, and its levels are negatively impacted by brood rearing and even by exposure to brood pheromone alone 30 . In addition to its role as a precursor of yolk protein in reproduction, Vg has also been implicated in the defense against reactive oxygen species [37][38][39] and as an enhancer of innate immunity 40 .…”

Immune-Related Genes of Megalurothrips usitatus (Bagrall) Against Beauveria brongniartii and Akanthomyces attenuatus Identified Using RNA Sequencing

“…Vitellogenin is another important insect protein, which is considered to provide nutrients for the development of yolk (Antúnez et al, 2013 ; Kodrík et al, 2019 ; Yang, 2020 ). However, many studies have shown that vitellogenins play important roles in the immune systems of amphioxus, potato psyllid, honeybees, Aedes aegypti , and so on (Raikhel et al, 2002 ; Antúnez et al, 2013 ; Shen et al, 2019 ).…”

Insect Body Defence Reactions against Bee Venom: Do Adipokinetic Hormones Play a Role?

“…Vitellogenins are actively involved in defence reactions against various pathogens [9]. There was a significant reduction in both ~100 kDa vitellogenin proteins by 8.2-fold and 2.9-fold in the female haemolymph 6 h after venom administration (Figure 8A,B).…”

“…The recent identification of vitellogenin in bee venom [7] suggests that it increases the allergenic properties of the venom; however, this has not been studied in detail. Vitellogenins are mostly known as yolk precursors involved in reproduction, but they also play important roles in protection against oxidative stress, wound healing, and insect immunity, with strong activity against bacteria and other pathogens [8,9].…”