Heat-shock induced proteins present in the cell nucleus of Chironomus tentans salivary gland.

The heat shock (HS) system has been largely studied in Drosophila but the molecular mechanisms responsible for the induction of the heat shock genes as well as the function(s) and the intracellular localisation of the induced proteins is still unknown. It has previously been shown that the HS puff induction is accompanied by a local increase of nuclear nonhistone proteins (NHP) but the nature of most of the proteins accumulating is unknown. We have investigated the effects of a heat shock on Chironomus tentans salivary glands, a system where it is possible to study constituents in various subcellular or intranuclear regions including individual puffs, by microdissection. We report here evidence that at least two of the polypeptides synthesised in response to the heat shock migrate to the nucleus. Furthermore, these two proteins appear to have a broad intranuclear distribution, as shown by their presence in the various microdissected nuclear fractions.