Temperature induced alterations in the liver of wall lizard (Hemidactylus frenatus): morphological and biochemical parameters.
Wall lizards (Hemidactylus frenatus) were adapted to 20, 25, and 30 degrees C, and the liver was examined using standard transmission electron microscopy (TEM) and biochemical analysis. Peroxisomes were visualized after using the 3,3'-diaminobenzidine (DAB) technique. Catalase, uricase and protein content were determined biochemically. The hepatocytes of animals adapted to higher temperature displayed larger lipid inclusions than those of animals adapted to lower temperature. Rough endoplasmic reticulum was better developed in the animals kept at low temperature (20 and 25 degrees C) than in the animals held at 30 degrees C. Cytoplasmic crystalline structures were visualized, and better developed in the hepatocytes at 25 degrees C. Peroxisomes varied with the temperature, being more frequent in the animals kept at 20 degrees C, while the bigger ones prevailed in the animals kept at 30 degrees C. The higher catalase activity at higher temperature was correlated to an increase in staining intensity of DAB-incubated peroxisomes as visualized cytochemically in TEM. The biochemical results confirmed the cytochemical reaction observed by TEM. The hepatocytes of the animals at 30 degrees C showed a reduction in the number of peroxisomes, however, at this temperature the largest peroxisomes with a stronger reaction to DAB and a higher activity of catalase predominate. In contrast, the uricase activity showed no significant variation in relation to adaptation temperature. Overall, these data show the morphological and functional plasticity of hepatocytes to temperature adaptation of H. frenatus.
de Brito-Gitirana
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Laboratório de Histologia Animal e Comparada, Universidade do Brasil-UFRJ, Av. Brigadeiro Trompowsky s/no, CCS, bl. F-2o andar, Rio de Janeiro, CEP 21044-970, Brazil. lyciabg@hotmail.com
Storch
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D000222:Adaptation, Physiological; D000818:Animals; D006358:Hot Temperature; D008099:Liver / Q000378:metabolism* / Q000648:ultrastructure*; D008116:Lizards / Q000033:anatomy & histology / Q000502:physiology*; D008297:Male; D008854:Microscopy, Electron