Induction of heat shock proteins in the larval fat body of Apis mellifera L. bees

Five proteins were expressed in larval honey bee fat bod incubated in vitro in response to heat shock, as shown by SDS-PAGE and fluorography. The larg e heat shock proteins (82, 70 kDa) were inducible throughout the 5th instar whereas the small ones (29, 26, 16 kDa) were inducible only in certain pha ses of this instar. The synthesis of these HSPs was accompanied by generali zed inhibition of overall protein synthesis and secretion in the culture me dium. Fluorograms showed that the 76 and 74 kDa proteins were strongly inhi bited by heat treatment. Western blots using a mouse monoclonal antibody ag ainst HSP72 and HSC73 permitted the inference that the 70 kDa larval protei n accumulated in the honey bee fat body in response to heat shock correspon ds to the HSP72 isoform. The Western blots also showed a 70 kDa faint band in fat bodies incubated at the control temperature (34 degrees C). This pro tein, also detected in incubation media independently of the temperature us ed, was interpreted as being the constitutively synthesized and secreted HS C73 isoform.