Expression of the 70 kDa Heat shock protein family in Alpine freshwater chironomids (Diptera, Chironomidae) under natural conditions

Abstract

Chironomidae represent up to 100% of the fauna of Alpine streams. Because they survive stress conditions such as extremely lowtemperature (annual mean cold and expression of stress proteins such as the 70 kDa Heat shock protein family. Fourth instar larvae of ten species of coldstenothermalchironomids (Pseudodiamesa branickii, Diamesa latitarsis, D. laticauda, D. cinerella, D. insignipes, D. zernyi, D.vaillanti, Orthocladius (O.) frigidus, O. (Euorthocladius) thienemanni and Paratrichocladius nivalis) were collected in a glacier-fedstream in NE Italy at two stations (1300 and 2600 m a.s.l.) and in two seasons (summer 2005 and spring 2006). Immunodetectionand quantification of the relative levels of Hsp70 family were performed via Western blot analysis. Significantly different levels ofHsp70 were detected among species. The highest amounts were recorded in P. nivalis and D. insignipes, the lowest in P. branickii.Within the genus Diamesa, lower levels of Hsp70 were observed in the most cold-stenothermal species than in the less coldstenothermalones. These differences may be explained by different species autoecology. The results provide information onbiochemical strategies of alpine midges to face cold temperatures under natural conditions and new insights into their possibleresponse to global warming.

Keywords

• cold-stenothermal species, Diamesinae, Orthocladiinae, glacial streams, stress proteins, Italian Alps