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Memórias do Instituto Oswaldo Cruz
Fundação Oswaldo Cruz, Fiocruz
ISSN: 1678-8060
EISSN: 1678-8060
Vol. 95, No. 6, 2000, pp. 893-898
Bioline Code: oc00146
Full paper language: English
Document type: Research Article
Document available free of charge

Memórias do Instituto Oswaldo Cruz, Vol. 95, No. 6, 2000, pp. 893-898

 en Changes in Nuclear Phenotypes Following Cold Shock in Panstrongylus megistus (Burmeister)
Simone L Garcia; Maria Luiza S Mello; Nancy L Garcia & Vera Lúcia CC Rodrigues


The nuclear phenotypes of Malpighian tubule epithelial cells of 5th instar male nymphs of the blood-sucking insect Panstrongylus megistus were studied immediately after a short (1 h) cold shock at 0oC, and 10 and 30 days later. The objective was to compare the responses to a cold shock with those known to occur after hyperthermia in order to provide insight into the cellular effect of cold in this species. Nuclei which usually exhibited a conspicuous Y chromosome chromocenter were the most frequent phenotype in control and treated specimens. Phenotypes in which the heterochromatin was unravelled, or in which there was nuclear fusion or cell death were more abundant in the shocked specimens. Most of the changes detected have also been found in heat-shocked nymphs, except for nuclear fusion which generates giant nuclei and which appeared to be less effective or necessary than that elicited after heat shock. Since other studies showed that a short cold shock does not affect the survival of more than 14% of 5th instar nymphs of P. megistus with domestic habit and can induce tolerance to a prolonged cold shock, heat shock proteins proteins are probably the best candidates for effective protection of the cells and the insects from drastic damage caused by low temperature shocks.

Panstrongylus megistus, cold shock, nuclear phenotypes, cell survival, cell death

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