Differences In Metabolic Profile In the Testes of Streptozotocin Induced Diabetes Mellitus Mice As Detected By 1H NMR

Contrary to the traditional view, recent studies suggest that diabetes mellitus has an adverse influence on male reproductive function. Our aim was to determine the affect of diabetes on the testicular environment by identifying and then assessing perturbations in small molecule metabolites. Testes were obtained from control and streptozotocin induced diabetic C57BL/6 mice, two, four and eight weeks post treatment. Diabetic status was confirmed by HbA1c, non fasting blood glucose, physiological condition and body weight. Protein free, low molecular weight, water soluble extracts were assessed using 1H NMR spectroscopy. Principal Component Analysis of the derived profiles was used to classify any variations and specific metabolites were identified based on their spectral pattern. Characteristic metabolite profiles were identified for control and diabetic animals with the most distinctive being from mice with the greatest physical deterioration and loss of bodyweight. Eight streptozotocin treated animals did not develop diabetes and displayed profiles similar to controls. Diabetic mice had decreases in creatine, choline and carnitine and increases in lactate, alanine and myo-inositol. Betaine levels were found to be increased in the majority of diabetic mice but decreased in two animals with severe loss of body weight and physical condition. The association between perturbations in a number of small molecule metabolites known to be influential in sperm function, with diabetic status and physiological condition, adds further impetus to the proposal that diabetes influences important spermatogenic pathways and mechanisms in a subtle and previously unrecognised manner.

Differences in composition of macroinvertebrate communities with invasive and native Gammarus spp. (Crustacea : Amphipoda)

1. Assessing the effects on communities of invasive species is often confounded by environmental factors. In Irish rivers, the introduced amphipod Gammarus pulex replaces the native G. duebeni celticus in lowland stretches. The two amphipods are associated with different macroinvertebrate communities, which may in part be the result of natural longitudinal physicochemical change. However, this hinders assessment of any direct community impacts of the invasive as compared with the native species. Here, we report on a fortuitous circumstance that allowed us to uncouple the community effects of Gammarus species from environmental differences.

Differences in resting metabolic rates of two southern African tortoises: Psammobates oculiferus and Geochelone pardalis

Energy metabolism varies considerably between different groups of endotherms, yet there is little or no reported variation among extant groups of reptiles. We measured lower resting metabolic rates (RMRs) in Kalahari tent tortoises (Psammobate oculiferus) than in sympatric Leopard tortoises (Geochelone pardalis). G pardalis also had RMR values that were higher than the allometric prediction for reptiles whereas P oculiferus had RMR values that were not significantly different from the prediction. Differences in RMR between the two species may have occurred because of the large differences in body mass, differing body temperatures, differences in growth rates, or because there may have been differences in the heat increment of feeding.

Energetics and litter size variation in domestic dog Canis familiaris breeds of two sizes

We measured resting metabolic rate (RMR), daily energy expenditure (DEE) and metabolisable energy intake (MEI) in two breeds of dog during peak lactation to test whether litter size differences were a likely consequence of allometric variation in energetics. RMR of Labrador retrievers (30 kg, n = 12) and miniature Schnauzers (6 kg, n = 4) averaged 3437 and 1062 kJ/day, respectively. DEE of Labradors (n = 6) and Schnauzers (n = 4) averaged 9808 and 2619 kJ/day, respectively. MEI of Labradors (n = 12) was 22448 kJ/day and of Schnauzers (a = 7) was 5382 kJ/day. DEE of Labrador pups (2.13 kg, n = 19) was 974 kJ/day and Schnauzers (0.89 kg, n = 7) were 490 kJ/day. Although Labradors had higher MEIs than Schnauzers during peak lactation, there was no difference in mass-specific energy expenditure between the two breeds. Hence, it is unlikely that litter size variation is a likely consequence of differences in maternal energy expenditure. Individual offspring were relatively more costly for mothers of the smaller breed to produce. Therefore, litter size variations were consistent with the expectation that smaller offspring should be more costly for mothers, but not that smaller mothers should per se invest more resources in reproduction. (C) 2001 Elsevier Science Inc. All rights reserved.