Oxidative damage and antioxidant defense are assay and tissue-dependent both in captive and wild-caught bank voles (Myodes glareolus) before and after reproduction

COVID-19 risk perception and negative emotional symptoms: Mediating role of self-control and moderating role of life history strategy

The coronavirus disease 2019 (COVID-19) has emerged as a significant public health crisis, posing threats to physical health and mental well-being. This study, grounded in the Risk-Resilience Model, sought to elucidate how COVID-19 risk perception impacts negative emotional symptoms. Specifically, we examined the mediating role of self-control and the moderating role of life history strategies. We conducted a two-wave longitudinal survey in October 2020 (N = 334) and November 2020 (N = 249), targeting residents across 14 provinces (24 cities) in China. After controlling for sex and age, the results supported the moderated mediation model, illustrating that (1) self-control mediated the relationship between COVID-19 risk perception and negative emotional symptoms, (2) life history strategy moderated the first segment of the mediation process, and (3) life history strategies also moderated the mediating effect of self-control on the link between COVID-19 risk perception and negative emotional symptoms. Furthermore, compared to a fast life history strategy, a slow life history strategy mitigated the effect of COVID-19 risk perception on self-control, thereby reducing negative emotional symptoms. This study sheds light on how COVID-19 risk perception affects negative emotional symptoms and identifies potential targets (i.e., self-control and life history strategy) for addressing emotional distress during pandemics.

Altered Oxidative Status as a Cost of Reproduction in a Seabird with High Reproductive Costs

AbstractLife history theory posits that reproduction is constrained by a cost of reproduction such that any increase in breeding effort should reduce subsequent survival. Oxidative stress refers to an imbalance between the prooxidant reactive oxygen species (ROS) and antioxidant defense. If not thwarted, ROS can cause damage to DNA, lipids, and proteins, potentially increasing the rate of senescence and decreasing cellular function. Reproduction is often associated with higher metabolic rates, which could increase production of ROS and lead to oxidative damage if the animal does not increase antioxidant protection. Thus, oxidative stress could be one mechanism creating a cost of reproduction. In this study we explored how reproduction may affect oxidative status differently between male and female thick-billed murres during early and late breeding seasons over three consecutive years. We manipulated breeding efforts by removing an egg from the nest of some individuals, which forced females to relay, and by handicapping other individuals by clipping wings. We measured total antioxidant capacity (TAC), uric acid (UA) concentration, and malondialdehyde (MDA; an index of lipid oxidative damage) concentration in blood plasma as well as activities of superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT) in red blood cells. Oxidative status was highly variable across years, and year was consistently the most important factor determining oxidative status; inconsistent results in previous field studies may be because reproductive oxidative stress occurs only in some years. Females had lower SOD and GPx and higher MDA and TAC than males immediately after egg laying, suggesting that the cost of egg laying required investment in cheaper nonenzymatic antioxidant defenses that had lower capacity for defending against lipid peroxidation. Delayed birds had lower UA and lower SOD, GPx, and CAT activity compared with control birds. In conclusion, when reproductive costs increase via higher energy costs or longer breeding seasons, the oxidative status of both male and female murres deteriorated as a result of reduced antioxidant defenses.

Implication of Membrane Androgen Receptor (ZIP9) in Cell Senescence in Regressed Testes of the Bank Vole

Here, we studied the impact of exposure to short daylight conditions on the expression of senescence marker (p16), membrane androgen receptor (ZIP9) and extracellular signal-regulated kinase (ERK 1/2), as well as cyclic AMP (cAMP) and testosterone levels in the testes of mature bank voles. Animals were assigned to groups based on an analysis of testis diameter, weight, seminiferous tubule diameter and the interstitial tissue area: group 1, not fully regressed (the highest parameters); group 2 (medium parameters); or group 3, regressed (the lowest parameters). Cells positive for p16 were observed only in the seminiferous tubule epithelium. However, in groups 1 and 2, these were mostly cells sloughed into the tubule lumen. In group 3, senescent cells resided in between cells of the seminiferous epithelium. Staining for ZIP9 was found in Sertoli cells. Western blot analysis showed a trend towards a decreased expression of p16 and ZIP9 in the testes of the voles in groups 2 and 3, compared to group 1. In addition, a trend towards an increased expression of ERK, as well as an increase of cAMP and testosterone levels, was revealed in group 2. In the regressed testes, a functional link exists between senescence and androgen levels with implication of ZIP9 and cAMP/ERK signaling pathways.

Reproduction and maternal care increase oxidative stress in a mouthbrooding cichlid fish

Investment in reproduction and postzygotic parental care is an energetically costly yet fundamental aspect of the life-history strategies in many species. Recently, oxidative stress has received attention as a potential mediator in the trade-off between reproduction, growth, and survival. During activities that increase metabolic activity, such as providing offspring care, an overproduction of reactive oxygen species can occur that cannot be counteracted by antioxidants, leading to oxidative stress and tissue damage. Here, we investigated the oxidative costs of reproduction and maternal care over the course of the reproductive cycle in a mouthbrooding cichlid fish within socially stable and unstable environments. We manipulated social stability by disrupting the habitat in socially unstable tanks. We expected to see an increase in the burden of maternal care within unstable environments due to increased male harassment of females as a byproduct of increased male–male aggression. We found that brooding females have higher levels of oxidative stress than nonbrooding females and oxidative stress fluctuates throughout the reproductive cycle. These fluctuations were driven by a spike in reactive oxygen metabolites at the beginning of brood care followed by an increase in antioxidant defense. Surprisingly, the link between reproduction and oxidative stress was not different between females from stable or unstable environments. Our study illustrates a more complete picture of the physiological costs of reproduction and parental care throughout different stages of care rather than a simplistic end-point observation of how reproduction and parental care affect an individual.