Egg protein insolubility in Lymantria dispar versus other forest lepidoptera

Fri, 11 Jul 2003

A standard buffer (5 mM phosphate at pH 7) which is used to extract prote in from insect eggs provided complete protein solubility for eggs from three of four tree-feeding lepidopteran species: obliquebanded leaf roller (C/lOris/Onelira rosaceana), forest tent caterpillar (Malacosoma disslria), and the eastern tent caterpillar (Malacosoma americanllln). Under the same extraction protocol, egg proteins from the gypsy moth(Lynumlria dispar), remained nearly insoluble. An array of methods typically used to solubilize insect egg proteins were tried and all but the most denaturing (2% SDS) were ineffective. Extraction buffers with typically high pH values were then evaluated. The results indicated that I) solubility of gypsy moth egg proteins was pH dependent, and full solubility of most egg proteins required the extraction buffer to have a pH of 12 or more prior to the addition of eggs. We also determined that 2) the gypsy moth egg has a buffering capacity which must be surpassed for complete protein extraction, 3) low salt/high pH buffers. gave slightly higher total protei n values than did high salt/high pH buffers, 4) parental nutritional history (host species utili zed) and egg developmental state (pre-embryonated vs postembryonated/ pre-hatch) were unrelated to the requirements for complete egg protein solubilization, and 5) the presence of soluble phenolics, compounds that have the potentia l to bind to protein and cause insolubility, was confirmed for the gypsy moth egg with 2-D paper chromatography and several other tests. Based on these results, we present a hypothesis about the cause of egg protein insolubility in the gypsy moth.

Publications by D. Bergeron

Egg protein insolubility in Lymantria dispar versus other forest lepidoptera