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Several cDNAs isolated from brains of diapausing pupae of the f lesh f ly, Sarcophaga crassipalpis, show expression patterns unique to diapause. To isolate such cDNAs a diapause pupal brain cDNA library was screened by using an elimination hybridization technique, and cDNAs that did not hybridize with cDNA probes constructed from the RNA of nondiapausing pupae were selected for further screening. The 95 clones that did not hybridize in the initial library screen were selected for further characterization. These clones were then screened against diapause and nondiapause pupal poly(A) ؉ Northern blots. The secondary screen identified 4 diapause-up-regulated clones, 7 diapause-down-regulated clones, 8 clones expressed equally in both diapause and nondiapause, and 75 clones without detectable expression. The diapause-up-regulated and down-regulated clones were further characterized by partial DNA sequencing and identity searches by using GenBank. Identities between our cloned cDNAs and other genes included those linked to cell cycle progression, stress responses, and DNA repair processes. The results suggest that insect diapause is not merely a shutdown of gene expression but is a unique, developmental pathway characterized by the expression of a novel set of genes.

Diapausing pharate first instars of the gypsy moth, Lymantria dispar, respond to high temperature (37-41°C) by suppressing normal protein synthesis and synthesizing a set of seven heat shock proteins with M, s of 9O,OOO, 75,000,73,000, 60,000,42,000,29,000, and 22,000 as determined by SDS-PAGE. During recovery at 25OC from heat shock, synthesis of the heat shock proteins gradually decreases over a period of 6 h, while normal protein synthesis i s restored. A subset of these same heat shock proteins is also expressed during recovery at 4°C or 25°C from brief exposures to low temperature (-10 to 2OoC), and its expression is more intense with increased severity of cold exposure. During recovery at 4°C after 24 h at -20°C, both 90,000 and 75,000 M, heat shock proteins are expressed for more than 96 h. While normal protein synthesis is suppressed during heat shock and recovery from heat shock, normal protein synthesis coincides with synthesis of the heat shock proteins during recovery from low temperatures, thus implying that expression of the heat shock proteins i s not invariably linked to suppression of normal protein synthesis. Western transfer, using a monoclonal antibody that recognizes the inducible form of the human 70,000 M, heat shock protein, demonstrates that immunologically related proteins in the gypsy moth are expressed at 4°C and during recovery from cold and heat shock.

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