RESUMEN
In a previous study oxidative damage markers - lipid peroxidation and protein oxidation - were determined in organs of wild Caiman yacare captured in winter-2001 and summer-2002 at various developmental stages. An increase in oxidative damage occurred in the hatchling-juvenile transition (but not in the juvenile-adult transition) and winter-summer transition (in juveniles), suggesting that oxidative stress is associated with development and season. Herein the effect of development and season on glutathione (GSH) metabolism and the effect of development on the activity of antioxidant enzymes (catalase, glutathione peroxidase, glutathione reductase and glutathione S-transferase) and glucose 6-phosphate dehydrogenase were analyzed. The ratio GSSG:GSH-eq increased in lung, liver, kidney and brain by 1.8- to 4-fold in the embryo/hatchling to juvenile transition. No changes occurred in juvenile-adult transition. GSSG:GSH-eq across seasons was significantly elevated in summer. Total-glutathione content was mostly stable in various organs; in liver it increased in the embryo-juvenile transition. Enzyme activities were only determined in summer-animals (embryos, hatchlings and juveniles). For most antioxidant enzymes, activities increased from embryo/hatchling to juvenile in liver and Kidney. In lung, there was an inverse trend for enzyme activities and total glutathione content. Thus, increased metabolic rates during early caiman growth - in embryo-juvenile transition - appears to be related to redox imbalance as suggested by increased GSSG:GSH-eq and activation of antioxidant defenses. Differences in oxidative stress across seasons were related with summer-winter nocturnal temperatures. These results, as a whole, were interpreted in the context of ecological biochemistry.
Asunto(s)
Caimanes y Cocodrilos/metabolismo , Antioxidantes/metabolismo , Glutatión/metabolismo , Hígado/enzimología , Humedales , Animales , Encéfalo/metabolismo , Brasil , Catalasa/metabolismo , Regulación Enzimológica de la Expresión Génica , Glucosafosfato Deshidrogenasa/metabolismo , Glutatión Peroxidasa/metabolismo , Glutatión Reductasa/metabolismo , Glutatión Transferasa/metabolismo , Riñón/metabolismo , Hígado/metabolismo , Pulmón/metabolismo , Masculino , Músculo Esquelético/metabolismo , Miocardio/metabolismo , Especificidad de Órganos , Estrés Oxidativo , Proteínas de Reptiles/metabolismo , Estaciones del AñoRESUMEN
Although science and engineering (S&E) publications and doctoral degree awards in Latin America had experienced an impressive growth in the past decades, a qualitative evaluation of this increased output must be performed. Previous studies have indicated that growth in visibility of Latin American science - determined by ratio of citations per paper - has not kept pace with the increase in number of publications. In the present editorial, we analyzed - by means of a 12-item questionnaire - the individual perceptions of forty senior researchers involved in CBP-Latin America (29 Brazilians and 11 non-Brazilians) plus a special group composed by six extraordinary Latin American scientists (the "masters"). The questionnaire - using 6-point Likert-like scale for quantification of perception - focused on issues surrounding doctoral educational system as well as the governmental educational policies and publication pressure from funding agencies. In general, the most striking result was the perception (by 82% of respondents) of lack of job opportunities for people holding a PhD diploma in the field of comparative biochemistry and physiology. Other major trends include (i) lack of satisfaction with governmental policies for science and post-graduate education due to policies promoting mass production for papers and PhD diplomas (65-77% of respondents felt that way) (ii) that current PhD students are doing an adequate job, but have not improved in quality as compared to those from 10 years ago (the same was observed for PhD thesis in terms of present versus past), and (iii) that research infrastructure and the curricula of post-graduate courses do not constitute a problem, but (iv) recent-PhDs are not as fit as they should be in paper-writing skills, especially as perceived by Brazilian respondents. The general perceptions were very similar among Brazilians, non-Brazilians and "masters". The use of a larger study-population, with scientists of more diverse fields is the next logical step to best evaluate the level of satisfaction about science and post-graduate policies in the continent. Finally, this fifth and last special issue of CBP-Latin America celebrates the contribution of 20 new manuscripts, which adds up to 118 published studies highlighting the depth, breadth and enthusiasm of Latin American comparative biochemistry and physiology - enjoy.
Asunto(s)
Bioquímica/educación , Educación de Postgrado/tendencias , Biología Molecular/educación , Fisiología/educación , Edición/tendencias , Actitud , Humanos , Factor de Impacto de la Revista , América Latina , Edición/estadística & datos numéricosRESUMEN
Crocodilians and other diving vertebrates experience hypoperfusion and hypoxia of several internal organs during long dives. At the end of a dive, reperfusion of aerated blood may cause a physiologically relevant oxidative stress. In this study, we analyzed selected markers of oxidative stress in eight organs of normoxic Paraguayan caiman (Caiman yacare) captured in the Brazilian Pantanal wetlands during the winter of 2001 (six mature-adult males and eight young-adult males; AD-1 and YA-1 groups, respectively), and during the summer of 2002 (six young-adult males (YA-2 group), ten hatchlings and five embryos). Lipid peroxidation products determined by three different assays were generally highest in brain, liver and kidney (in comparison with all other organs), and lowest in white muscles from the tail and hind legs. Liver and kidney showed the highest levels of carbonyl protein, while brain showed low levels. Intermediate levels of oxidative stress markers were mostly found in the heart ventricles and lung. Differences in oxidative stress markers between AD-1 and YA-1 were organ-specific, showing no age-related correlation. However, most oxidative stress markers in YA-2 organs were either higher than (by 1.4- to 3.7-fold) or not significantly different from respective values in hatchlings organs. This pattern (hatchlings versus young-adults) was confirmed using correlation analysis of individual caiman size versus levels of oxidative damage markers in four organs. The higher level of oxidative stress markers in young-adults possibly relates to the fast growth rate (and thus, increased oxidative metabolic rate) of C. yacare in the first years of life. Differences in oxidative stress markers between YA-1 and YA-2 were also observed and were ascribed to seasonal changes in free radical metabolism. These results in normoxic C. yacare represent the first step towards understanding the age-related physiological oxidative stress of a diving reptile from a seasonally changing wetland environment.