Erythrocyte lifespan in dwarf and normal pullets from growth selected lines of chickens

Resistance to glycation in the zebra finch: Mass spectrometry-based analysis and its perspectives for evolutionary studies of aging

In humans, hyperglycemia is associated with protein glycation, which may contribute to aging. Strikingly, birds usually outlive mammals of the same body mass, while exhibiting high plasma glucose levels. However, how birds succeed in escaping pro-aging effects of glycation remains unknown. Using a specific mass spectrometry-based approach in captive zebra finches of known age, we recorded high glycaemia values but no glycated hemoglobin form was found. Still, we showed that zebra finch hemoglobin can be glycated in vitro, albeit only to a limited extent compared to its human homologue. This may be due to peculiar structural features, as supported by the unusual presence of three different tetramer populations with balanced proportions and a still bound cofactor that could be inositol pentaphosphate. High levels of the glycated forms of zebra finch plasma serotransferrin, carbonic anhydrase 2, and albumin were measured. Glucose, age or body mass correlations with either plasma glycated proteins or hemoglobin isoforms suggest that those variables may be future molecular tools of choice to monitor glycation and its link with individual fitness. Our molecular advance may help determine how evolution succeeded in associating flying ability, high blood glucose and long lifespan in birds.

Chromatin supraorganization, DNA fragmentation, and cell death in snake erythrocytes

In nucleate erythrocytes of several vertebrate groups, the frequency and intensity of DNA fragmentation associated with programed cell death vary considerably. Although hemoglobin efficiency may be related to erythrocyte life span, and hemoglobin types and erythrocyte life spans are assumed to vary in reptiles, no data on DNA fragmentation and chromatin organization as related to cell death exist for snakes. In the present study, chromatin supraorganization, DNA fragmentation, and cell death were investigated in four snake species (Crotalus durissus terrificus, Bothrops jararaca, Bothrops alternatus, and Bothrops neuwiedii), which differ in their geographical distribution and habitats, by using image analysis of Feulgen hydrolysis kinetics, the TUNEL assay, single-cell gel electrophoresis, and transmission electron microscopy. Relatively few circulating erythrocytes were found to be simultaneously committed to cell death, although there was some variation among the snake species. Conspicuous nuclear and cytoplasmic organelles suggestive of metabolic activity were seen ultrastructurally in most snake erythrocytes. The DNA of the snake erythrocyte chromatin was much more resistant to Feulgen acid hydrolysis (DNA depurination and breakdown) than that of young adult bullfrog erythrocytes, which had a high frequency and intensity of DNA fragmentation. Of the species studied, B. neuwiedii and C. d. terrificus showed the greatest resistance to Feulgen acid hydrolysis and to the DNA fragmentation, revealed by the TUNEL assay. Although B. neuwiedii also showed the lowest frequency of cells with more damaged DNA in the single-cell gel electrophoresis assay, C. d. terrificus had the highest frequency of damaged cells, possibly because of the abundance of alkaline-sensitive DNA sites. The results for DNA fragmentation and cell death in erythrocytes of B. jararaca and B. alternatus generally differed from those for C. d. terrificus and B. neuwiedii and may reflect differences in the biology of these species selected under different geographical habitats. The differences in erythrocyte cell biology reported here may be related to hemoglobin variants selected in the mentioned snake species and that would lead the cells to different resistances to unfavorable environmental conditions.Key words: erythrocytes, snakes, DNA fragmentation, chromatin supraorganization, cell death.