RESUMO

Dietary fat quality affects overall systemic parameters and produce hepatic accumulation of fat and inflammation (steatohepatitis). In this communication we have assessed how mouse liver nuclear phenotypes are influenced by diets containing 7% lipid prepared with lard, linseed oil or soybean oil for 32 weeks. Liver specimens were imprinted on glass slides, fixed and stained with DAPI. 3D confocal images were obtained and employed for the calculation of nuclear thickness, nuclear volume and DAPI-DNA intensity. Hepatocytes' nuclei could be classified as diploid A, diploid B, tetraploid and higher ploidy levels. Linseed oil in the diet resulted in increased frequency of diploid A (more compact) and less polyploidy, while lard caused increased volume and more polyploidy. Soybean oil produced intermediate nuclear sizes. The results suggest a high demand on liver physiology promoted by lard, which has a predominance of saturated fatty acids, while linseed oil promoted the opposite effect.

RESUMO

The frequency of polyploid nuclei in the aging human heart is in sharp contrast with that in the human liver. An inverse pattern exists between the mouse heart and liver cells. Ploidy degrees in mouse hepatocytes under hyperglycemic conditions are elevated to higher levels than those in aged hepatocytes. In this study, image analysis cytometry was used to investigate the effect of diabetes and aging on Feulgen-DNA quantities, ploidy degrees, nuclear shapes and chromatin texture in mouse cardiomyocytes compared to previously reported data for mouse hepatocytes. Adult, non-obese diabetic (NOD) hyperglycemic and normoglycemic females and 56-week-old normoglycemic BALB/c females were used. A small percentage (∼7%) of the cardiomyocyte nuclei in severely hyperglycemic NOD adult mice possessed higher ploidy values than those in the 8-week-old normoglycemic mice. Surprisingly, the Feulgen-DNA values and the frequency of nuclei belonging to the 4C and 8C ploidy classes were even higher (∼6%) in normoglycemic NOD specimens than in age-matched hyperglycemic NOD specimens. Additionally, a pronounced elongated nuclear shape was observed especially in adult normoglycemic NOD mice. In conclusion, NOD mice, irrespective of their glycemic level, exhibit a moderate increase in ploidy degrees within cardiomyocyte nuclei during the adult lifetime. As expected, aging did not affect the Feulgen-DNA values and the ploidy degrees of cardiomyocytes in BALB/c mice. The differences in ploidy degrees and chromatin textures such as absorbance variability and entropy, between adult NOD and aged BALB/c mice are consistent with other reports, indicating dissimilarities in chromatin functions between diabetes and aging.

Assuntos

RESUMO

This study aimed to contribute to our knowledge of the parasite-vector interaction associated with Trypanosoma cruzi (Chagas, 1909) infection in Panstrongylus megistus (Burmeister, 1835), an important vector of Chagas' disease in Brazil. The prevalence and intensity of T. cruzi infection, the incidence of metacyclogenesis and the frequency of nuclear phenotypes in Malpighian tubules were investigated in nymphs of P. megistus, reared at 28 °C and subjected to heat shock (40 °C, 1 hour) two days after infection with T. cruzi II (Y strain). Following the 45-day post-infection period, the frequency of epimastigotes was much higher than that of trypomastigotes in both heat-shocked and non-shocked insects, and the prevalence of infection was not altered by heat shock. Fewer epimastigotes and trypomastigotes were found in the infected insects subjected to the heat shock, indicating that the multiplication and metacyclogenesis of the parasites were affected by the stress. In infected specimens heat shock promoted an increased frequency of cell nuclei with heterochromatin decondensation, a cell survival response to stress, and did not affect insect survival. The effects of infection and heat shock, especially on the multiplication and metacyclogenesis of T. cruzi, and the observed resistance to heat shock developed by P. megistus nymphs are suggestive that they should be considered when adequate conditions for rearing these infected insects in the laboratory are pursued.

O presente estudo teve como objetivo contribuir para o conhecimento sobre a interação parasita-vetor associada à infecção por Trypanosoma cruzi (Chagas, 1909) em Panstrongylus megistus (Burmeister, 1835), importante vetor da doença de Chagas no Brasil. A prevalência e a intensidade da infecção por T. cruzi, a incidência de metaciclogênese e a frequência de fenótipos nucleares presentes em túbulos de Malpighi foram investigadas em ninfas de P. megistus criadas à temperatura de 28 °C e submetidas a choque térmico por 1 hora a 40 °C, dois dias após alimentação em camundongos infectados com T. cruzi II (linhagem Y). A análise realizada 45 dias pós-infecção revelou que tanto nos insetos submetidos ao choque térmico como nos respectivos controles a frequência de epimastigotos se apresentava muito maior do que a dos tripomastigotos; a prevalência da infecção não foi alterada pelo choque térmico. Menos epimastigotos e tripomastigotos foram encontrados nos insetos submetidos ao choque térmico, indicando que a multiplicação e a metaciclogênese dos parasitas possam ser afetadas com o estresse. Nos espécimes infectados, o choque térmico induziu aumento na frequência de núcleos com descompactação da heterocromatina, uma resposta de sobrevivência celular ao estresse, e não afetou a sobrevivência propriamente dita do inseto. Os efeitos da infecção e do choque térmico, especialmente sobre a multiplicação e a metaciclogênese de T. cruzi, e a resistência ao choque térmico desenvolvidos pelas ninfas de P. megistus são indicativos de que devam ser considerados quando se buscam condições adequadas de criação em laboratório de insetos infectados.

Assuntos

RESUMO

This study aimed to contribute to our knowledge of the parasite-vector interaction associated with Trypanosoma cruzi (Chagas, 1909) infection in Panstrongylus megistus (Burmeister, 1835), an important vector of Chagas' disease in Brazil. The prevalence and intensity of T. cruzi infection, the incidence of metacyclogenesis and the frequency of nuclear phenotypes in Malpighian tubules were investigated in nymphs of P. megistus, reared at 28 °C and subjected to heat shock (40 °C, 1 hour) two days after infection with T. cruzi II (Y strain). Following the 45-day post-infection period, the frequency of epimastigotes was much higher than that of trypomastigotes in both heat-shocked and non-shocked insects, and the prevalence of infection was not altered by heat shock. Fewer epimastigotes and trypomastigotes were found in the infected insects subjected to the heat shock, indicating that the multiplication and metacyclogenesis of the parasites were affected by the stress. In infected specimens heat shock promoted an increased frequency of cell nuclei with heterochromatin decondensation, a cell survival response to stress, and did not affect insect survival. The effects of infection and heat shock, especially on the multiplication and metacyclogenesis of T. cruzi, and the observed resistance to heat shock developed by P. megistus nymphs are suggestive that they should be considered when adequate conditions for rearing these infected insects in the laboratory are pursued.(AU)

O presente estudo teve como objetivo contribuir para o conhecimento sobre a interação parasita-vetor associada à infecção por Trypanosoma cruzi (Chagas, 1909) em Panstrongylus megistus (Burmeister, 1835), importante vetor da doença de Chagas no Brasil. A prevalência e a intensidade da infecção por T. cruzi, a incidência de metaciclogênese e a frequência de fenótipos nucleares presentes em túbulos de Malpighi foram investigadas em ninfas de P. megistus criadas à temperatura de 28 °C e submetidas a choque térmico por 1 hora a 40 °C, dois dias após alimentação em camundongos infectados com T. cruzi II (linhagem Y). A análise realizada 45 dias pós-infecção revelou que tanto nos insetos submetidos ao choque térmico como nos respectivos controles a frequência de epimastigotos se apresentava muito maior do que a dos tripomastigotos; a prevalência da infecção não foi alterada pelo choque térmico. Menos epimastigotos e tripomastigotos foram encontrados nos insetos submetidos ao choque térmico, indicando que a multiplicação e a metaciclogênese dos parasitas possam ser afetadas com o estresse. Nos espécimes infectados, o choque térmico induziu aumento na frequência de núcleos com descompactação da heterocromatina, uma resposta de sobrevivência celular ao estresse, e não afetou a sobrevivência propriamente dita do inseto. Os efeitos da infecção e do choque térmico, especialmente sobre a multiplicação e a metaciclogênese de T. cruzi, e a resistência ao choque térmico desenvolvidos pelas ninfas de P. megistus são indicativos de que devam ser considerados quando se buscam condições adequadas de criação em laboratório de insetos infectados.(AU)

Assuntos