In vivo modulation of Hsp70 in Rhynchophorus ferrugineus hemocytes after Bacillus thuringiensis treatment

Abstract

Heat shock proteins (Hsps) are rapidly synthesized within stressed cells after exposure to an environmental stressor. A variety of environmental stresses, including heat, cold, trace-metal exposure, xenobiotics have been reported to modulate Hsps expression in various organisms. Hsps are grouped into several families based on their protein size. Most organisms have several genes encoding members of this Hsp family. In particularly Hsp70 can be induced quickly under stressful conditions, but return to a normal expression level under non-stressful conditions. Few studies have been done to detect the Hsp70 expression in phytophagous insects towards pathogens. Since a preliminary research disclosed that Bacillus thuringiensis (Bt) negatively interacts with R. ferrugineus circulating hemocytes so that their number was dramatically decreased. In the present research we examine the expression of Hsp70 in hemocytes from R. ferrugineus larvae feed with a commercial product based on Bt. Western blot analyses using monoclonal anti-HSP 70 antibody showed that the expression of Hsp 70 was modulated reaching the highest value, seven times highest to the control, after 3h from the treatment. The Hsp70 values had the same value of the control at 6 hours. Monitoring the Hsp70 for 48 hours we notice a further decrement. This result highlights a stress condition, caused by Bt, as showed also by the reduction of the larval weight. So Hsp70 may be a suitable tool to detect rapidly stress condition induced by potential entomopathogens.