The metabolic rate of cultured muscle cells from hybrid Coturnix quail is intermediate to that of muscle cells from fast-growing and slow-growing Coturnix quail

Is There Hybrid Vigor in Dogs? Oxidative Stress and Cytokine Concentrations in Low- To Mid-Content Wolf-Dog Hybrids

AbstractChanges of deleterious traits in mitochondria within hybrids of two different species are likely to be reflected across whole-animal phenotypes. Two processes linked to mitochondrial fitness are oxidative stress and inflammation. Here, plasma oxidative stress (lipid oxidative damage, total antioxidant capacity, and activities of catalase, glutathione peroxidase, and superoxide dismutase concentration) and cytokine concentrations (IL-1β, IL-6, and TNF-α) from wolf-dog hybrids of low to mid wolf content are presented and then compared with previously published values for similar-sized dogs and gray wolves. Results indicate that lipid oxidative damage and catalase activity were not significantly different across species and hybrids. Total antioxidant capacity and glutathione peroxidase were significantly lower in wolf-dog hybrids than in domestic dogs and wolves (although total antioxidant capacity significantly increased with wolf content), but superoxide dismutase concentration was higher in hybrids. Thus, it seems that a low percentage of wolf content decreases several aspects of antioxidants but without any accumulating lipid oxidative damage. Additionally, wolf-dog hybrids had higher IL-1β and IL-6 concentrations but lower TNF-α concentrations than domestic dogs. And there was a significantly positive correlation between percentage of wolf content and IL-1β. These data imply either a mitonuclear incompatibility or a nuclear-nuclear incompatibility within wolf-dog hybrids, a case that does not support heterosis.

The resistance of domestic canine skin-derived fibroblasts to oxidative and non-oxidative chemical injury: implications of breed and body size

Small-breed dogs live significantly longer lives than large-breed dogs, while having higher mass-specific metabolic rates and faster growth rates. Underlying this observed physiological difference across domestic dogs, there must also be differences at other levels of organization that could lead to elucidating what accounts for the disparity in aging rates and life span within this species. At the cellular level, a clear mechanism underlying whole animal traits has not been fully elucidated. Here, we cultured dermal fibroblasts from large and small breed dogs from both young and old age categories and examined the degree of resistance to multiple sources of cytotoxic stress. This included heat (42 °C), paraquat, cadmium, and hydrogen peroxide for increasing amounts of time (heat) or increasing concentrations (chemical stressors). We hypothesized that small breed dogs, with longer lifespans, would have greater cellular resistance to stress compared with large breed dogs. Final sample sizes include small puppies (N = 18), large puppy (N = 32), small old (N = 11), and large old (N = 23) dogs. Using a 2 (donor size) by 2 (donor age) between-subjects multivariate analysis of variance, we found that the values for the dose that killed 50% of the cells (LD50) were not significantly different based on donor size (p = 0.45) or donor age (p = 0.20). The interaction was also not significant (p = 0.47). Interestingly, we did find that the degree of resistance to cadmium toxicity was significantly correlated with the degree of resistance to both heat and hydrogen peroxide, but not paraquat (p < 0.01 for both). These data suggest that cellular stress resistance does not differ among domestic dogs as a function of size or age, pointing to other cellular pathways as the mechanistic basis for the observed differences in lifespan.

Primary Cell Culture as a Model System for Evolutionary Molecular Physiology

Primary cell culture is a powerful model system to address fundamental questions about organismal physiology at the cellular level, especially for species that are difficult, or impossible, to study under natural or semi-natural conditions. Due to their ease of use, primary fibroblast cultures are the dominant model system, but studies using both somatic and germ cells are also common. Using these models, genome evolution and phylogenetic relationships, the molecular and biochemical basis of differential longevities among species, and the physiological consequences of life history evolution have been studied in depth. With the advent of new technologies such as gene editing and the generation of induced pluripotent stem cells (iPSC), the field of molecular evolutionary physiology will continue to expand using both descriptive and experimental approaches.

Species-specific metabolic responses of songbird, shorebird, and murine cultured myotubes to n-3 polyunsaturated fatty acids

Migratory birds may benefit from diets rich in polyunsaturated fatty acids (PUFAs) that could improve exercise performance. Previous investigations suggest that different types of birds may respond differently to PUFA. We established muscle myocyte cell culture models from muscle satellite cells of a migratory passerine songbird (yellow-rumped warbler, Setophaga coronata coronata) and a nonpasserine shorebird (sanderling, Calidris alba). We differentiated and treated avian myotubes and immortalized murine C₂C₁₂ myotubes with n-3 PUFA docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), and with monounsaturated oleic acid (OA) to compare effects on aerobic performance, metabolic enzyme activities, key fatty acid (FA) transporters, and expression of peroxisome proliferator-activated receptors (PPARs). Sanderling and C₂C₁₂ myotubes increased expression of PPARs with n-3 PUFA treatments, whereas expression was unchanged in yellow-rumped warblers. Both sanderlings and yellow-rumped warblers increased expression of fatty acid transporters, whereas C₂C₁₂ cells decreased expression following n-3 PUFA treatments. Only yellow-rumped warbler myotubes increased expression of some metabolic enzymes, whereas the sanderling and C₂C₁₂ cells were unchanged. PUFA supplementation in C₂C₁₂ myotubes increased mitochondrial respiratory chain efficiency, whereas sanderlings increased proton leak-associated respiration and maximal respiration (measurements were not made in warblers). This research indicates that songbirds and shorebirds respond differently to n-3 PUFA and provides support for the hypothesis that n-3 PUFA increase the aerobic capacity of migrant shorebird muscle, which may improve overall endurance flight performance.

Oxidative stress does not differ in primary dermal fibroblasts isolated from fast-growing and control-growing Japanese Quail (Coturnix japonica)

Growth rate is a key life-history trait that influences fitness and shapes the physiology of organisms. Additionally, faster growing individuals of the same species seem to be burdened with higher whole-animal metabolism and higher cellular turnover rates, which may lead to increases in oxidative stress, though this fact remains controversial within the literature. Aerobic organisms are subjected to metabolic by-products known as reactive oxygen species (ROS), which can wreak havoc on macromolecules, such as structurally altering proteins and inducing mutations in DNA, among others. To combat accumulating damage, organisms have evolved endogenous antioxidants and can consume exogenous antioxidants to sequester ROS before they cause cellular damage. We used primary fibroblast cells isolated from control-growing and fast-growing Japanese Quail (Coturnix japonica Temminck and Schlegel, 1849) as a study model for the effects of differing growth rates on oxidative stress. We measured reduced glutathione (GSH) concentration, ROS production, mitochondrial content, and lipid peroxidation (LPO) damage. We found no significant differences in the four parameters measured between control-growing and fast-growing Quail. However, we found that in fast-growing Quail, GSH correlated with LPO damage and mitochondrial content, and LPO damage positively correlated with mitochondrial content, whereas control-growing Quail only showed positive relationships between LPO damage and ROS production.