Reactive oxygen species as universal constraints in life-history evolution

Alleviating Pentatrichomonas hominis-induced damage in IPEC-J2 cells: the beneficial influence of porcine-derived lactobacilli

Pentatrichomonas hominis is a common intestinal parasitic protozoan that causes abdominal pain and diarrhea, and poses a zoonotic risk. Probiotics, known for enhancing immunity and pathogen resistance, hold promise in combating parasitic infections. This study aimed to evaluate two porcine-derived probiotics, Lactobacillus reuteri LR1 and Lactobacillus plantarum LP1, against P. hominis infections in pigs. Taxonomic identity was confirmed through 16 S rRNA gene sequencing, with L. reuteri LR1 belonging to L. reuteri species and L. plantarum LP1 belonging to L. plantarum species. Both probiotics exhibited robust in vitro growth performance. Co-culturing intestinal porcine epithelial cell line (IPEC-J2) with these probiotics significantly improved cell viability compared with the control group. Pre-incubation probiotics significantly enhanced the mRNA expression of anti-oxidative response genes in IPEC-J2 cells compared with the PHGD group, with L. reuteri LR1 and L. plantarum LP1 significantly up-regulating CuZn-SOD、CAT and Mn-SOD genes expression (p < 0.05). The anti-oxidative stress effect of L. reuteri LR1 was significantly better than that of L. plantarum LP1 (p < 0.05). Furthermore, pre-incubation with the probiotics alleviated the P. hominis-induced inflammatory response. L. reuteri LR1 and L. plantarum LP1 significantly down-regulated IL-6、IL-8 and TNF-α gene expression(p < 0.05) compared with the PHGD group. The probiotics also mitigated P. hominis-induced apoptosis. L. reuteri LR1 and L. plantarum LP1 significantly down-regulated Caspase3 and Bax gene expression (p < 0.05), significantly up-regulated Bcl-2 gene expression (p < 0.05) compared with the PHGD group. Among them, L. plantarum LP1 showed better anti-apoptotic effect. These findings highlight the probiotics for mitigating P. hominis infections in pigs. Their ability to enhance anti-oxidative responses, alleviate inflammation, and inhibit apoptosis holds promise for therapeutic applications. Simultaneously, probiotics can actively contribute to inhibiting trichomonal infections, offering a novel approach for preventing and treating diseases such as P. hominis. Further in vivo studies are required to validate these results and explore their potential in animal and human health.

The Life-History Traits of Soil-Dwelling Nematode (Acrobeloides sp.) Exhibit More Resilience to Water Restriction Than Caenorhabditis elegans

In the context of climate warming, the intensity and frequency of drought occurrences are progressively increasing. However, current research on the impacts of drought on the life-history traits and physiological activities of animals rarely encompasses soil animals that play crucial roles within soil ecosystems. Therefore, this study focused on a soil nematode species (Acrobeloides sp.) and a model nematode (Caenorhabditis elegans) to investigate whether nematodes adjust the trade-off of their life-history traits to confront arid environments, utilizing a Petri dish experiment. Subsequently, we assessed the resilience of the two nematode species to moisture variations by comparing the extent of changes in various indicators (i.e., life-history traits, physiological traits, and oxidative stress) of nematodes before and after drought and rehydration. The results revealed that both nematode species are capable of adapting to arid environments by altering the trade-off between life-history traits. Specifically, they reduce reproductive investment and body mass while maintaining life span, thus responding to drought conditions. Follow-up rehydration experiments post-drought stress highlighted that the soil-dwelling nematode exhibits a superior recovery capacity in response to moisture fluctuations in comparison to the model nematode. To the best of our knowledge, this is the first investigation into life history of drought adaptation within soil-dwelling nematodes. Moreover, the findings hold significant implications for the exploration of drought adaptation and its mechanisms in soil-dwelling animals.

Association between the three-dimensional facial shape and its color in a boundary group of young to middle-aged Asian women

Visual cues strongly influence an individual's self-esteem and have fundamental sociopsychological functions. The color and shape of the face are important information for visual cues and are hypothesized to be correlated with each other. However, few studies have examined these relationships. Thus, this study determined the association between color and shape of the face. For this purpose, we evaluated Chinese women in their 30s and 40s (n = 166). Three-dimensional (3D) image-capture devices that provide shape morphology along with standardized photographs (color information) were used to obtain 3D images of women. The coordinates and red‒green-blue color data on the 3D images were utilized to perform principal component (PC) analysis, and shape and color PCs were generated. A canonical variate analysis was then conducted to check for significant correlations between the shape and color PCs. As a result, 6 significant correlations were found (p < 0.05). In detail, in addition to the physical correlations (i.e., steric faces or faces with protrusion of the cheek showed greater shadows, retrognathism was related to a shadow under the lower lip and vice versa), biological correlations (fatty faces showed greater redness and remarkable marionette lines; faces with age-related sagging showed greater darkness, possibly related to cumulative ultraviolet radiation exposure of the skin; and robust mandibles and supraorbital ridges were related to thick eyebrows) were found. This insight can aid both medical and cosmetic practitioners in comprehending the intricate details conveyed by facial features, thereby facilitating more comprehensive diagnosis and treatment planning, including makeup.

Correlated evolution of oxidative physiology and MHC-based immunosurveillance in birds

Maintenance and activation of the immune system incur costs, not only in terms of substrates and energy but also via collateral oxidative damage to host cells or tissues during immune response. So far, associations between immune function and oxidative damage have been primarily investigated at intra-specific scales. Here, we hypothesized that pathogen-driven selection should favour the evolution of effective immunosurveillance mechanisms (e.g. major histocompatibility complex, MHC) and antioxidant defences to mitigate oxidative damage resulting from immune function. Using phylogenetically informed comparative approaches, we provided evidence for the correlated evolution of host oxidative physiology and MHC-based immunosurveillance in birds. Species selected for more robust MHC-based immunosurveillance (higher gene copy numbers and allele diversity) showed stronger antioxidant defences, although selection for MHC diversity still showed a positive evolutionary association with oxidative damage to lipids. Our results indicate that historical pathogen-driven selection for highly duplicated and diverse MHC could have promoted the evolution of efficient antioxidant mechanisms, but these evolutionary solutions may be insufficient to keep oxidative stress at bounds. Although the precise nature of mechanistic links between the MHC and oxidative stress remains unclear, our study suggests that a general evolutionary investment in immune function may require co-adaptations at the level of host oxidative metabolism.

Role-reversed polyandry is associated with faster fast-Z in shorebirds

In birds, males are homogametic and carry two copies of the Z chromosome ('ZZ'), while females are heterogametic and exhibit a 'ZW' genotype. The Z chromosome evolves at a faster rate than similarly sized autosomes, a phenomenon termed 'fast-Z evolution'. This is thought to be caused by two independent processes-greater Z chromosome genetic drift owing to a reduced effective population size, and stronger Z chromosome positive selection owing to the exposure of partially recessive alleles to selection. Here, we investigate the relative contributions of these processes by considering the effect of role-reversed polyandry on fast-Z in shorebirds, a paraphyletic group of wading birds that exhibit unusually diverse mating systems. We find stronger fast-Z effects under role-reversed polyandry, which is consistent with particularly strong selection on polyandrous females driving the fixation of recessive beneficial alleles. This result contrasts with previous research in birds, which has tended to implicate a primary role of genetic drift in driving fast-Z variation. We suggest that this discrepancy can be interpreted in two ways-stronger sexual selection acting on polyandrous females overwhelms an otherwise central role of genetic drift, and/or sexual antagonism is also contributing significantly to fast-Z and is exacerbated in sexually dimorphic species.

Reproductive toxicity assessment of cellulose nanofibers, citric acid, and branched polyethylenimine in sea urchins: Eco-design of nanostructured cellulose sponge framework (Part B)

In the framework of a safe-by-design approach, we previously assessed the eco-safety of nanostructured cellulose sponge (CNS) leachate on sea urchin reproduction. It impaired gamete quality, gamete fertilization competence, and embryo development possibly due to the leaching of chemical additives used during the CNS synthesis process. To extend this observation and identify the component(s) that contribute to CNS ecotoxicity, in the present study, we individually screened the cytotoxic effects on sea urchin Arbacia lixula and Paracentrotus lividus gametes and embryos of the three main constituents of CNS, namely cellulose nanofibers, citric acid, and branched polyethylenimine. The study aimed to minimize any potential safety risk of these components and to obtain an eco-safe CNS. Among the three CNS constituents, branched polyethylenimine resulted in the most toxic agent. Indeed, it affected the physiology and fertilization competence of male and female gametes as well as embryo development in both sea urchin species. These results are consistent with those previously reported for CNS leachate. Moreover, the characterisation of CNS leachate confirmed the presence of detectable branched polyethylenimine in the conditioned seawater even though in a very limited amount. Altogether, these data indicate that the presence of branched polyethylenimine is a cause-effect associated with a significant risk in CNS formulations due to its leaching upon contact with seawater. Nevertheless, the suggested safety protocol consisting of consecutive leaching treatments and conditioning of CNS in seawater can successfully ameliorate the CNS ecotoxicity while maintaining the efficacy of its sorbent properties supporting potential environmental applications.

Coevolution of longevity and female germline maintenance

An often-overlooked aspect of life-history optimization is the allocation of resources to protect the germline and secure safe transmission of genetic information. While failure to do so renders significant fitness consequences in future generations, germline maintenance comes with substantial costs. Thus, germline allocation should trade off with other life-history decisions and be optimized in accordance with an organism's reproductive schedule. Here, we tested this hypothesis by studying germline maintenance in lines of seed beetle, selected for early (E) or late (L) reproduction for 350 and 240 generations, respectively. Female animals provide maintenance and screening of male gametes in their reproductive tract and oocytes. Here, we reveal the ability of young and aged E- and L-females to provide this form of germline maintenance by mating them to males with ejaculates with artificially elevated levels of protein and DNA damage. We find that germline maintenance in E-females peaks at young age and then declines, while the opposite is true for L-females, in accordance with the age of reproduction in the respective regime. These findings identify the central role of allocation to secure germline integrity in life-history evolution and highlight how females can play a crucial role in mitigating the effects of male germline decisions on mutation rate and offspring quality.

No correlative evidence of costs of infection or immunity on leucocyte telomere length in a wild population of Soay sheep

Telomere length (TL) is a biomarker hypothesized to capture evolutionarily and ecologically important physiological costs of reproduction, infection and immunity. Few studies have estimated the relationships among infection status, immunity, TL and fitness in natural systems. The hypothesis that short telomeres predict reduced survival because they reflect costly consequences of infection and immune investment remains largely untested. Using longitudinal data from a free-living Soay sheep population, we tested whether leucocyte TL was predicted by infection with nematode parasites and antibody levels against those parasites. Helminth parasite burdens were positively associated with leucocyte TL in both lambs and adults, which is not consistent with TL reflecting infection costs. We found no association between TL and helminth-specific IgG levels in either young or old individuals which suggests TL does not reflect costs of an activated immune response or immunosenescence. Furthermore, we found no support for TL acting as a mediator of trade-offs between infection, immunity and subsequent survival in the wild. Our results suggest that while variation in TL could reflect short-term variation in resource investment or environmental conditions, it does not capture costs of infection and immunity, nor does it behave like a marker of an individual's helminth-specific antibody immune response.

Mitochondrial genetic variation as a potential mediator of intraspecific behavioural diversity

Mitochondrial genes play an essential role in energy metabolism. Variation in the mitochondrial DNA (mtDNA) sequence often exists within species, and this variation can have consequences for energy production and organismal life history. Yet, despite potential links between energy metabolism and the expression of animal behaviour, mtDNA variation has been largely neglected to date in studies investigating intraspecific behavioural diversity. We outline how mtDNA variation and interactions between mitochondrial and nuclear genotypes may contribute to the expression of individual-to-individual behavioural differences within populations, and why such effects may lead to sex differences in behaviour. We contend that integration of the mitochondrial genome into behavioural ecology research may be key to fully understanding the evolutionary genetics of animal behaviour.

A revisiting of "the hallmarks of aging" in domestic dogs: current status of the literature

A progressive decline in biological function and fitness is, generally, how aging is defined. However, in 2013, a description on the "hallmarks of aging" in mammals was published, and within it, it described biological processes that are known to alter the aging phenotype. These include genomic instability, telomere attrition, epigenetic alterations, loss of proteostasis, deregulated nutrient sensing, mitochondrial dysfunction, cellular senescence, stem cell exhaustion, altered intercellular communication (inflammation), and changes within the microbiome. This mini-review provides a detailed account of the progress on each of these hallmarks of aging in the domestic dog within the last 5 years. Additionally, when there are gaps in the literature between other mammalian species and dogs, I highlight the aging biomarkers that may be missing for dogs as aging models. I also argue for the importance of dog aging studies to include several breeds of dogs at differing ages and for age corrections for breeds with differing mean lifespans throughout.

Heat stress reveals a fertility debt owing to postcopulatory sexual selection

Climates are changing rapidly, demanding equally rapid adaptation of natural populations. Whether sexual selection can aid such adaptation is under debate; while sexual selection should promote adaptation when individuals with high mating success are also best adapted to their local surroundings, the expression of sexually selected traits can incur costs. Here we asked what the demographic consequences of such costs may be once climates change to become harsher and the strength of natural selection increases. We first adopted a classic life history theory framework, incorporating a trade-off between reproduction and maintenance, and applied it to the male germline to generate formalized predictions for how an evolutionary history of strong postcopulatory sexual selection (sperm competition) may affect male fertility under acute adult heat stress. We then tested these predictions by assessing the thermal sensitivity of fertility (TSF) in replicated lineages of seed beetles maintained for 68 generations under three alternative mating regimes manipulating the opportunity for sexual and natural selection. In line with the theoretical predictions, we find that males evolving under strong sexual selection suffer from increased TSF. Interestingly, females from the regime under strong sexual selection, who experienced relaxed selection on their own reproductive effort, had high fertility in benign settings but suffered increased TSF, like their brothers. This implies that female fertility and TSF evolved through genetic correlation with reproductive traits sexually selected in males. Paternal but not maternal heat stress reduced offspring fertility with no evidence for adaptive transgenerational plasticity among heat-exposed offspring, indicating that the observed effects may compound over generations. Our results suggest that trade-offs between fertility and traits increasing success in postcopulatory sexual selection can be revealed in harsh environments. This can put polyandrous species under immediate risk during extreme heat waves expected under future climate change.

Medical prospects of cryptosporidiosis in vivo control using biofabricated nanoparticles loaded with Cinnamomum camphora extracts by Ulva fasciata

Background and Aim

Global efforts are continuing to develop preparations against cryptosporidiosis. This study aimed to investigate the efficacy of biosynthesized Ulva fasciata loading Cinnamomum camphora oil extract on new zinc oxide nanoparticles (ZnONPs shorten to ZnNPs) and silver nanoparticles (AgNPs) as alternative treatments for Cryptosporidium parvum experimental infection in rats.

Materials and Methods

Oil extract was characterized by gas chromatography-mass spectrometry, loaded by U. fasciata on ionic-based ZnO and NPs, and then characterized by transmission electron microscopy, scanning electron microscopy, and X-ray diffraction. Biosafety and toxicity were investigated by skin tests. A total of 105 C. parvum oocysts/rat were used (n = 81, 2-3 W, 80-120 g, 9 male rats/group). Oocysts shedding was counted for 21 d. Doses of each preparation in addition to reference drug were administered daily for 7 d, starting on post-infection (PI) day (3). Nitazoxanide (100 mg) was used as the reference drug. After 3 weeks, the rats were sacrificed for postmortem examination and histopathological examination. Two blood samples/rat/group were collected on the 21st day. Ethylenediaminetetraacetic acid blood samples were also used for analysis of biochemistry, hematology, immunology, micronucleus prevalence, and chromosomal abnormalities.

Results

C. camphora leaves yielded 28.5 ± 0.3 g/kg oil and 20 phycocompounds were identified. Spherical and rod-shaped particles were detected at 10.47-30.98 nm and 18.83-38.39 nm, respectively. ZnNPs showed the earliest anti-cryptosporidiosis effect during 7-17 d PI. Other hematological, biochemical, immunological, histological, and genotoxicity parameters were significantly fruitful; hence, normalized pathological changes induced by infestation were observed in the NPs treatments groups against the infestation-free and Nitazoxanide treated group.

Conclusion

C. camphora, U. fasciata, ZnNPs, and AgNPs have refluxed the pathological effects of infection as well as positively improved host physiological condition by its anticryptosporidial immunostimulant regenerative effects with sufficient ecofriendly properties to be proposed as an alternative to traditional drugs, especially in individuals with medical reactions against chemical commercial drugs.

Molecular cloning and characterization of Cu-Zn superoxide dismutase (sod1) gene in brown trout and its expression in response to acute aquaculture stressors

Aquaculture species are often exposed to acute stressors such as low water levels and handling during routine aquaculture procedures. This might result in oxidative stress by the increased reactive oxygen species (ROS)' production (e.g., superoxide anion). The harmful effects of ROS are eliminated by a defense system, referred antioxidant defense system (ADS). sod1 is the first gene involved in the ADS. Therefore, we cloned and characterized the open reading frame of the sod1 in brown trout. Then, we determined the effects of low water level and handling stress on sod1 mRNA expression in the liver and gills at 0 min, 1 and 2 h. The total RNA isolated was used to synthesize cDNA for RT-qPCR analysis. Phylogenetic tree, identity/similarity percentages, genomic organization, and conserved gene synteny analyses were applied to characterize Sod1/sod1. While low water level stress upregulated sod1 expression in the liver compared to the control group, no significant differences were observed in the gills between experimental groups. However, brown trout differently responded to handling stress at different time intervals in both tissues. Transcriptional differences were also noted between the sexes. This study contributes to the current understanding of the molecular mechanism between oxidative stress and ADS.

Chronic Thermal Acclimation Effects on Critical Thermal Maxima (CTmax) and Oxidative Stress Differences in White Epaxial Muscle between Surface and Cave Morphotypes of the Mexican Cavefish (Astyanax mexicanus)

AbstractIn the face of increasing environmental temperatures, operative differences between mitochondrial function and whole-animal phenotypic response to the environment are underrepresented in research, especially in subtemperate ectothermic vertebrates. A novel approach to exploring this connection is to examine model species that are genetically similar but that have different whole-animal phenotypes, each of which inhabits different environments. The blind Mexican cavefish (Astyanax mexicanus) has the following two morphotypes: a surface form found in aboveground rivers and an obligate cave-dwelling form. Each morphotype inhabits vastly different thermal and oxygen environments. Whole-animal and mitochondrial responses to thermal acclimation and oxidative stress, with respect to increasing temperatures, have not been previously determined in either morphotype of this species. Here, we chronically acclimated both morphotypes to three temperatures (14°C, 25°C, and 31°C) to establish potential for acclimation and critical thermal maxima (CTmax) for each morphotype of this species. After measuring CTmax in six cohorts, we additionally measured enzymatic antioxidant capacity (catalase, superoxide dismutase, and glutathione peroxidase activities), peroxyl scavenging capacity, and lipid peroxidation damage in white epaxial muscle for each individual. We found a significant effect of acclimation temperature on CTmax (F = 29.57 , P < 0.001 ) but no effect of morphotype on CTmax (F = 2.092 , P = 0.162 ). Additionally, we found that morphotype had a significant effect on glutathione peroxidase activity, with the surface morphotype having increased glutathione peroxidase activity compared with the cave morphotype (F = 6.270 , P = 0.020 ). No other oxidative stress variable demonstrated significant differences. Increases in CTmax with chronic thermal acclimation to higher temperatures suggests that there is some degree of phenotypic plasticity in this species that nominally occupies thermally stable environments. The decreased glutathione peroxidase activity in the cave morphotype may be related to decreased environmental oxygen concentration and decreased metabolic rate in this environmentally constrained morphotype compared to in its surface-living counterparts.

Social status influences relationships between hormones and oxidative stress in a cichlid fish

An individual's social environment can have widespread effects on their physiology, including effects on oxidative stress and hormone levels. Many studies have suggested that variation in oxidative stress experienced by individuals of different social statuses might be due to endocrine differences, however, few studies have evaluated this hypothesis. Here, we assessed whether a suite of markers associated with oxidative stress in different tissues (blood/plasma, liver, and gonads) had social status-specific relationships with circulating testosterone or cortisol levels in males of a cichlid fish, Astatotilapia burtoni. Across all fish, blood DNA damage (a global marker of oxidative stress) and gonadal synthesis of reactive oxygen species [as indicated by NADPH-oxidase (NOX) activity] were lower when testosterone was high. However, high DNA damage in both the blood and gonads was associated with high cortisol in subordinates, but low cortisol in dominants. Additionally, high cortisol was associated with greater production of reactive oxygen species (greater NOX activity) in both the gonads (dominants only) and liver (dominants and subordinates). In general, high testosterone was associated with lower oxidative stress across both social statuses, whereas high cortisol was associated with lower oxidative stress in dominants and higher oxidative stress in subordinates. Taken together, our results show that differences in the social environment can lead to contrasting relationships between hormones and oxidative stress.

Antioxidant Activity of Coumarins and Their Metal Complexes

Ubiquitously present in plant life, coumarins, as a class of phenolic compounds, have multiple applications-in everyday life, in organic synthesis, in medicine and many others. Coumarins are well known for their broad spectrum of physiological effects. The specific structure of the coumarin scaffold involves a conjugated system with excellent charge and electron transport properties. The antioxidant activity of natural coumarins has been a subject of intense study for at least two decades. Significant research into the antioxidant behavior of natural/semi-synthetic coumarins and their complexes has been carried out and published in scientific literature. The authors of this review have noted that, during the past five years, research efforts seem to have been focused on the synthesis and examination of synthetic coumarin derivatives with the aim to produce potential drugs with enhanced, modified or entirely novel effects. As many pathologies are associated with oxidative stress, coumarin-based compounds could be excellent candidates for novel medicinal molecules. The present review aims to inform the reader on some prominent results from investigations into the antioxidant properties of novel coumarin compounds over the past five years.

Impacts of Deoxygenation and Hypoxia on Shark Embryos Anti-Predator Behavior and Oxidative Stress

Climate change is leading to the loss of oxygen content in the oceans and endangering the survival of many marine species. Due to sea surface temperature warming and changing circulation, the ocean has become more stratified and is consequently losing its oxygen content. Oviparous elasmobranchs are particularly vulnerable as they lay their eggs in coastal and shallow areas, where they experience significant oscillations in oxygen levels. Here, we investigated the effects of deoxygenation (93% air saturation) and hypoxia (26% air saturation) during a short-term period (six days) on the anti-predator avoidance behavior and physiology (oxidative stress) of small-spotted catshark (Scyliorhinus canicula) embryos. Their survival rate decreased to 88% and 56% under deoxygenation and hypoxia, respectively. The tail beat rates were significantly enhanced in the embryos under hypoxia compared to those exposed to deoxygenation and control conditions, and the freeze response duration showed a significant opposite trend. Yet, at the physiological level, through the analyses of key biomarkers (SOD, CAT, GPx, and GST activities as well as HSP70, Ubiquitin, and MDA levels), we found no evidence of increased oxidative stress and cell damage under hypoxia. Thus, the present findings show that the projected end-of-the-century deoxygenation levels elicit neglectable biological effects on shark embryos. On the other hand, hypoxia causes a high embryo mortality rate. Additionally, hypoxia makes embryos more vulnerable to predators, because the increased tail beat frequency will enhance the release of chemical and physical cues that can be detected by predators. The shortening of the shark freeze response under hypoxia also makes the embryos more prone to predation.

Modification of Sugar Profile and Ripening in Atemoya (Annona × atemoya Mabb.) Fruits through Copper Hydroxide Application

Atemoya (Annona × atemoya Mabb.), a climacteric fruit of the Annonaceae family, is becoming increasingly popular due to its organoleptic and nutritional properties. Anthracnose, a fungus of the Colletotrichum genus, is one of the most serious diseases in orchards, causing significant damage if not controlled, so producers use phytosanitary products. The current study sought to investigate the quality of atemoya fruits after harvest in an orchard with anthracnose controlled by Cu(OH)² application: T1-no Cu(OH)², T2-7.8 mL Cu(OH)² L1 divided into two applications, T3-15.6 mL Cu(OH)² L1 divided into four, T4-8.0 mL Cu(OH)² L1 divided into eight, and T5-13.0 mL Cu(OH)² L1 divided into thirteen applications. The sugar profile of fruits was examined, as well as MDA, H₂O₂, and quality parameters such as pH, mass, soluble solids, titratable acidity, and maturation index. MDA, such as H₂O₂, can function as a signal molecule. Eight applications of 1.0 mL L-1 Cu(OH)² resulted in increased concentrations of H₂O₂ and MDA, signal molecules involved in sugar modification profiles such as glucose, fructose, and trehalose. It also had a high titratable acidity, a lower maturation index, better fruit quality, and a longer shelf life.

Anoxia hormesis improves performance and longevity at the expense of fitness in a classic life history trade-off

Hormesis occurs as a result of biphasic dose relationship resulting in stimulatory responses at low doses and inhibitory ones at high doses. In this framework, environmental factors are often studied to understand how this exposure benefits the animal. In the current study we used anoxia, the total absence of oxygen, as the most extreme version of low oxygen hormesis. Our goal was to determine the dose, the extent of the effect, and the cost of that response in Tenebrio molitor. We identified that the hormetic range (1 to 3 h of anoxia) was similar to that of other insects. Individuals that were exposed to 3 h had high emergence, increased activity throughout life, and lived longer. Beetles that experienced 1 h of anoxia performed better than the controls while the 6-h group had compromised performance. These boosts in performance at 3 h were accompanied by significant costs. Treated individuals had a delay in development and once matured they had decreased fitness. There were also transgenerational effects of hormesis and F₁ beetles also experienced a delay in development. Additionally, the F₁ generation had decreased developmental completion (i.e., stress-induced developmental halt). Our data suggests that anoxia hormesis triggers a trade-off where individuals benefiting from improved performance and living longer experience a decrease in reproduction.

The role of taurine in male reproduction: Physiology, pathology and toxicology

Taurine, a sulfur-containing amino acid, has a wide range of biological effects, such as bile salt formation, osmotic regulation, oxidative stress inhibition, immunomodulation and neuromodulation. Taurine has been proved to be synthesized and abundant in male reproductive organs. Recently, accumulating data showed that taurine has a potential protective effect on reproductive function of male animals. In physiology, taurine can promote the endocrine function of the hypothalamus-pituitary-testis (HPT) axis, testicular tissue development, spermatogenesis and maturation, delay the aging of testicular structure and function, maintain the homeostasis of the testicular environment, and enhance sexual ability. In pathology, taurine supplement may be beneficial to alleviate pathological damage of male reproductive system, including oxidative damage of sperm preservation in vitro, testicular reperfusion injury and diabetes -induced reproductive complications. In addition, taurine acts as a protective agent against toxic damage to the male reproductive system by exogenous substances (e.g., therapeutic drugs, environmental pollutants, radiation). Related mechanisms include reduced oxidative stress, increased antioxidant capacity, inhibited inflammation and apoptosis, restored the secretory activity of the HPT axis, reduced chromosomal variation, enhanced sperm mitochondrial energy metabolism, cell membrane stabilization effect, etc. Therefore, this article reviewed the protective effect of taurine on male reproductive function and its detailed mechanism, in order to provide reference for further research and clinical application.

How telomere dynamics are influenced by the balance between mitochondrial efficiency, reactive oxygen species production and DNA damage

It is well known that oxidative stress is a major cause of DNA damage and telomere attrition. Most endogenous reactive oxygen species (ROS) are produced in the mitochondria, producing a link between mitochondrial function, DNA integrity and telomere dynamics. In this review we will describe how ROS production, rates of damage to telomeric DNA and DNA repair are dynamic processes. The rate of ROS production depends on mitochondrial features such as the level of inner membrane uncoupling and the proportion of time that ATP is actively being produced. However, the efficiency of ATP production (the ATP/O ratio) is positively related to the rate of ROS production, so leading to a trade-off between the body's energy requirements and its need to prevent oxidative stress. Telomeric DNA is especially vulnerable to oxidative damage due to features such as its high guanine content; while repair to damaged telomere regions is possible through a range of mechanisms, these can result in more rapid telomere shortening. There is increasing evidence that mitochondrial efficiency varies over time and with environmental context, as do rates of DNA repair. We argue that telomere dynamics can only be understood by appreciating that the optimal solution to the trade-off between energetic efficiency and telomere protection will differ between individuals and will change over time, depending on resource availability, energetic demands and life history strategy.

Experimental removal of nematode parasites increases growth, sprint speed, and mating success in brown anole lizards

Parasites interact with nearly all free-living organisms and can impose substantial fitness costs by reducing host survival, mating success, and fecundity. Parasites may also indirectly affect host fitness by reducing growth and performance. However, experimentally characterizing these costs of parasitism is challenging in the wild because common antiparasite drug formulations require repeated dosing that is difficult to implement in free-living populations, and because the extended-release formulations that are commercially available for livestock and pets are not suitable for smaller animals. To address these challenges, we developed a method for the long-term removal of nematode parasites from brown anole lizards (Anolis sagrei) using an extended-release formulation of the antiparasite drug ivermectin. This treatment eliminated two common nematode parasites in captive adult males and dramatically reduced the prevalence and intensity of infection by these parasites in wild adult males and females. Experimental parasite removal significantly increased the sprint speed of captive adult males, the mating success of wild adult males, and the growth of wild juveniles of both sexes. Although parasite removal did not have any effect on survival in wild anoles, parasites may influence fitness directly through reduced mating success and indirectly through reduced growth and performance. Our method of long-term parasite manipulation via an extended-release formulation of ivermectin should be readily adaptable to many other small vertebrates, facilitating experimental tests of the extent to which parasites affect host phenotypes, fitness, and eco-evolutionary dynamics in the wild.

Oxidative Stress Is a Potential Cost of Synchronous Nesting in Olive Ridley Sea Turtles

Olive ridley sea turtles, Lepidochelys olivacea, exhibit a polymorphic reproductive behavior, nesting solitarily or in mass aggregations termed “arribadas”, where thousands of individuals nest synchronously. Arribada nesting provides fitness benefits including mate finding during nearshore aggregations and predator satiation at the time of hatching, but it is unknown if such benefits come with a physiological cost. We used plasma metabolite profiling, stable isotope analysis, biochemical and endocrine assays to test whether metabolic parameters differ between nesting modes, and if arribada nesting is associated with increased levels of oxidative damage compared to solitary nesting. Arribada nesters were bigger and had higher circulating thyroid hormone levels than solitary nesters. Similarly, pathways related to phospholipid and amino acid metabolism, catabolic processes, and antioxidant defense were enriched in individuals nesting in arribada. Stable isotope signatures in skin samples showed differences in feeding zones with arribada nesters likely feeding on benthic and potentially more productive grounds. Arribada nesters had increased levels of plasma lipid peroxidation and protein oxidation products compared to solitary nesters. These results suggest that metabolic profiles differ between nesting modes and that oxidative stress is a trade-off for the fitness benefits associated with arribada nesting.

Bacterial supergroup-specific "cost" of Wolbachia infections in Nasonia vitripennis

The maternally inherited endosymbiont, Wolbachia, is known to alter the reproductive biology of its arthropod hosts for its own benefit and can induce both positive and negative fitness effects in many hosts. Here, we describe the effects of the maintenance of two distinct Wolbachia infections, one each from supergroups A and B, on the parasitoid host Nasonia vitripennis. We compare the effect of Wolbachia infections on various traits between the uninfected, single A‐infected, single B‐infected, and double‐infected lines with their cured versions. Contrary to some previous reports, our results suggest that there is a significant cost associated with the maintenance of Wolbachia infections where traits such as family size, fecundity, longevity, and rates of male copulation are compromised in Wolbachia‐infected lines. The double Wolbachia infection has the most detrimental impact on the host as compared to single infections. Moreover, there is a supergroup‐specific negative impact on these wasps as the supergroup B infection elicits the most pronounced negative effects. These negative effects can be attributed to a higher Wolbachia titer seen in the double and the single supergroup B infection lines when compared to supergroup A. Our findings raise important questions on the mechanism of survival and maintenance of these reproductive parasites in arthropod hosts.

Defining the link between oxidative stress, behavioural reproductive suppression and heterothermy in the Natal mole-rat (Cryptomys hottentotus natalensis)

Sub-lethal effects, such as oxidative stress, can be linked to various breeding and thermophysiological strategies, which themselves can be linked to seasonal variability in abiotic factors. In this study, we investigated the subterranean, social living Natal mole-rat (Cryptomys hottentotus natalensis), which, unlike other social mole-rat species, implements heterothermy seasonally in an attempt to avoid exercise-induced hyperthermia and relies solely on behavioural reproductive suppression to maintain reproductive skew in colonies. Subsequently, we investigated how oxidative stress varied between season, sex and breeding status in Natal mole-rats. Oxidative markers included total oxidant status (TOS measure of total peroxides present), total antioxidant capacity (TAC), OSI (oxidative stress index) and malondialdehyde (MDA) to measure oxidative stress. Breeding and non-breeding mole-rats of both sexes were captured during the summer (wet season) and winter (dry season). Seasonal environmental variables (air temperature, soil temperature and soil moisture) had a significant effect on TOS, OSI and MDA, where season affected each sex differently. Unlike other social mole-rat species that use both physiological and behavioural means of reproductive suppression, no oxidative costs to reproduction were present in the Natal mole-rats. Males had significantly higher MDA than females, which was most apparent in summer (wet season). We conclude that the significant oxidative damage in males is a consequence of exercise-induced oxidative stress, exacerbated by increased burrow humidities and poorer heat dissipation abilities as a function of body mass. This study highlights the importance of both breeding and thermophysiological strategies in affecting oxidative stress.

Biochemical and osmoregulatory responses of the African clawed frog experimentally exposed to salt and pesticide

Salinization and pollution are two main environmental stressors leading deterioration to water quality and degradation of aquatic ecosystems. Amphibians are a highly sensitive group of vertebrates to environmental disturbance of aquatic ecosystems. However, studies on the combined effect of salinization and pollution on the physiology of amphibians are limited. In this study, we measured the standard metabolic rate (SMR) and biochemical parameters of adult males of the invasive frog Xenopus laevis after 45 days of exposure to contrasting salinity environments (400 and 150 mOsm NaCl) with either 1.0 μg/L of the organophosphate pesticide chlorpyrifos (CPF) or pesticide-free medium. Our results revealed a decrease in SMR of animals exposed to the pesticide and in the ability to concentrate the plasma in animals exposed simultaneously to both stressors. The lack of ability to increase plasma concentration in animals exposed to both salt water and CPF, suggests that osmoregulatory response is decreased by pesticide exposure. In addition, we found an increase of liver citrate synthase activity in response to salt stress. Likewise, the liver acetylcholinesterase (AChE) activity decreased by 50% in frogs exposed to salt water and CPF and 40% in those exposed only to CPF, which suggest an additive effect of salinity on inhibition of AChE. Finally, oxidative stress increased as shown by the higher lipid peroxidation and concentration of aqueous peroxides found in the group exposed to salt water and pesticide. Thus, our results revealed that X. laevis physiology is compromised by salinization and pesticide exposure to both environmental stressors join.

Hordeum vulgare L. microgreen mitigates reproductive dysfunction and oxidative stress in streptozotocin‐induced diabetes and aflatoxicosis in male rats

Diabetes mellitus type 2 (DM) is a common chronic disease worldwide, which may be due to increased environmental pollution. Aflatoxin B1 is a likely inevitable contaminant in food and dairy products. Both DM and aflatoxicosis exert a deleterious effect on reproduction urging the exploration of various functional food for protection. This study investigated the effect of barley microgreen (BM) on reproductive disorders caused by DM with or without aflatoxicosis in male rats. Rats were divided into eight groups; G1 control, G2 barley, G3 aflatoxin, G4 aflatoxin‐barley, G5 streptozotocin (STZ), G6 STZ‐barley, G7 STZ‐aflatoxin, and G8 STZ‐aflatoxin‐barley. BM chemical composition revealed elevated calcium, iron, phosphorus, and vitamin A compared with barely seeds. Complete blood picture, lipid profile, serum oxidative stress parameters, relative testicular weight, sperm analysis, chromosomal aberration, and testis histopathology were performed. The lipid profile was altered significantly in G7. Oxidative stress was increased in G3, G5, and G7, whereas it was decreased in BM‐treated groups. Sperm counts were reduced significantly in aflatoxin and/or STZ groups but increased significantly in BM‐treated groups. Sperm morphological abnormalities and chromosomal aberrations were decreased significantly in BM‐treated groups compared with untreated groups. Testicular histopathology revealed moderate diffuse degeneration of seminiferous tubules in aflatoxin and/or STZ groups, which were alleviated in BM‐treated groups. In conclusion, aflatoxin and STZ together caused severe reproductive disorder and oxidative stress more than aflatoxin or STZ alone. BM diet reduced significantly oxidative stress and reproductive disorder associated with DM and aflatoxicosis in rats.

Use of giant unilamellar lipid vesicles as antioxidant carriers in in vitro culture medium of bovine embryos

Giant unilamellar vesicles (GUVs) are composed of lipophilic layers and are sensitive to the action of reactive oxygen species (ROS). The use of GUVs as microcarriers of biological macromolecules is particularly interesting since ROS produced by gametes or embryos during in vitro culture can induce the opening of pores in the membrane of these vesicles and cause the release of their content. This study investigated the behavior of GUVs [composed of 2-dioleoyl-sn-glycero-3-phosphocholine and 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine-N-(lissamine rhodamine B sulfonyl)] in co-culture with in vitro produced bovine embryos, as well as their embryotoxicity and effectiveness as cysteine carriers in culture medium. Embryonic developmental rates were unaffected, demonstrating the absence of toxicity of GUVs co-cultured with the embryos. No increase of intracellular ROS levels was observed in the embryos co-cultured with GUVs, indicating that the higher lipid content of the culture environment resulting from the lipid composition of the GUV membrane itself did not increase oxidative stress. Variations in the diameter and number of GUVs demonstrated their sensitivity to ROS produced by embryos cultured under conditions that generate oxidative stress. Encapsulation of cysteine in GUVs was found to be more effective in controlling the production of ROS in embryonic cells than direct dilution of this antioxidant in the medium. In conclusion, the use of GUVs in in vitro culture was found to be safe since these vesicles did not promote toxic effects nor did they increase intracellular ROS concentrations in the embryos. GUVs were sensitive to oxidative stress, which resulted in structural changes in response to the action of ROS. The possible slow release of cysteine into the culture medium by GUV rupture would therefore favor the gradual supply of cysteine, prolonging its presence in the medium. Thus, the main implication of the use of GUVs as cysteine microcarriers is the greater effectiveness in preventing the intracytoplasmic increase of ROS in in vitro produced bovine embryos.

Integrative Analysis of Metabolomic and Transcriptomic Data Reveals the Antioxidant Potential of Dietary Lutein in Chickens

Lutein can increase the body's skin color and has antioxidant potential. However, how it affects lipid metabolism and oxidative stress in chickens remains unknown. In this study, 74-day-old male chickens raised on feed supplemented with lutein had higher hip, back, breast, leg, shin and abdominal fat yellowness than the control group, and the livers of chickens in the lutein group had higher superoxide dismutase and glutathione peroxidase and lower malondialdehyde activities. To clarify the potential regulatory network regulated by lutein, we used RNA-seq and nontargeted metabolomics to detect changes in the male chicken liver and plasma, respectively. A total of 243 differentially expressed genes were significantly enriched in cytokine–cytokine receptor interaction signaling pathways, among others. A total of 237 significantly different metabolites were enriched in lysine biosynthesis and degradation and glycerophospholipid metabolism signaling pathways, among others. Finally, we comprehensively analyzed metabolome and transcriptome data and found that many differentially expressed genes and significantly different metabolites play crucial roles in lipid metabolism and oxidative stress. In summary, dietary lutein can improve male chicken skin yellowness and antioxidant indices and affect liver gene expression and plasma metabolites and may help improve the health of chickens.

Differences in advanced glycation endproducts (AGEs) in plasma from birds and mammals of different body sizes and ages

Birds and mammals provide a physiological paradox: similar-sized mammals live shorter lives than birds; yet, birds have higher blood glucose concentrations than mammals, and higher basal metabolic rates. We have previously shown that oxidative stress patterns between mammals and birds differ, so that birds, generally, have lower blood antioxidant capacity, and lower lipid peroxidation concentration. There is a close association between oxidative stress and the production of carbohydrate-based damaged biomolecules, Advanced Glycation End-products (AGEs). In mammals, AGEs can bind to their receptor (RAGE), which can lead to increases in reactive oxygen species (ROS) production, and can decrease antioxidant capacity. Here, we used plasma from birds and mammals to address whether blood plasma AGE-BSA concentration is associated with body mass and age in these two groups. We found a statistically significantly higher average concentrations of AGE-BSA in birds compared with mammals, and we found a significantly positive correlation between AGE-BSA and age in mammals, though, this correlation disappeared after phylogenetic correction. We propose that the higher AGE concentration in birds is mainly attributable to greater AGE-production due to elevated basal glucose concentrations and decreased AGE-clearance given differences in glomerular filtration rates in birds compared with mammals. Additionally, due to the potential lack of an AGE receptor in birds, AGE accumulation may not be closely linked to oxidative stress and therefore pose a lesser physiological challenge in birds compared to mammals.

Biliverdin/Bilirubin Redox Pair Protects Lens Epithelial Cells against Oxidative Stress in Age-Related Cataract by Regulating NF-κB/iNOS and Nrf2/HO-1 Pathways

Age-related cataract (ARC) is the leading cause of vision impairment globally. It has been widely accepted that excessive reactive oxygen species (ROS) accumulation in lens epithelial cells (LECs) is a critical risk factor for ARC formation. Biliverdin (BV)/bilirubin (BR) redox pair is the active by-product of heme degradation with robust antioxidative stress and antiapoptotic effects. Thus, we purpose that BV and BR may have a therapeutic effect on ARC. In the present study, we determine the expression levels of enzymes regulating BV and BR generation in human lens anterior capsule samples. The therapeutic effect of BV/BR redox pair on ARC was assessed in hydrogen peroxide (H₂O₂)-damaged mouse LECs in vitro. The NF-κB/inducible nitric oxide synthase (iNOS) and nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) signaling pathways were evaluated to illustrate the molecular mechanism. The results revealed that the mRNA expressions of Nrf2, HO-1, and biliverdin reductase A (BVRA) were all decreased in human samples of age-related nuclear cataract. BV/BR redox pair pretreatment protected LECs against H₂O₂ damage by prohibiting NF-κB p65 nuclear trafficking, ameliorating iNOS expression, reducing intracellular and mitochondrial ROS levels, and restoring glutathione (GSH) and superoxide dismutase (SOD) levels. BV and BR pretreatment also regulated the expression of apoptotic molecules (Bax, Bcl-2, and cleaved caspase-3), thus decreasing the apoptosis of LECs. In addition, BV/BR pair promoted Nrf2 nuclear accumulation and HO-1 induction, whereas the knockdown of BVRA counteracted the effect of BV on activating Nrf2/HO-1 pathway and antiapoptosis. These findings implicated that BV/BR redox pair protects LECs against H₂O₂-induced apoptosis by regulating NF-κB/iNOS and Nrf2/HO-1 pathways. Moreover, BVRA is responsible for BV-mediated cytoprotection by reductive conversion of BV to BR. This trial is registered with ChiCTR2000036059.

Oxidative Stress in the Protection and Injury of the Lacrimal Gland and the Ocular Surface: are There Perspectives for Therapeutics?

Oxidative stress (OS) is a major disruption in the physiology of the lacrimal functional unit (LFU). Antioxidant enzymes have dual protective activities: antioxidant and antimicrobial activities. Peroxidases have been indistinctly used as markers of the secretory activity of the LFU and implicated in the pathophysiology, diagnosis and treatment of dry eye disease (DED), even though they comprise a large family of enzymes that includes lactoperoxidase (LPO) and glutathione peroxidase (GPO), among others. Assays to measure and correlate OS with other local LFU phenomena have methodological limitations. Studies implicate molecules and reactions involved in OS as markers of homeostasis, and other studies identify them as part of the physiopathology of diseases. Despite these conflicting concepts and observations, it is clear that OS is influential in the development of DED. Moreover, many antioxidant strategies have been proposed for its treatment, including calorie restriction to nutritional supplementation. This review offers a critical analysis of the biological mechanisms, diagnostic outcomes, drug use, dietary supplements, and life habits that implicate the influence of OS on DED.

Untangling the oxidative cost of reproduction: An analysis in wild banded mongooses

The cost of reproduction plays a central role in evolutionary theory, but the identity of the underlying mechanisms remains a puzzle. Oxidative stress has been hypothesized to be a proximate mechanism that may explain the cost of reproduction. We examine three pathways by which oxidative stress could shape reproduction. The “oxidative cost” hypothesis proposes that reproductive effort generates oxidative stress, while the “oxidative constraint” and “oxidative shielding” hypotheses suggest that mothers mitigate such costs through reducing reproductive effort or by pre‐emptively decreasing damage levels, respectively. We tested these three mechanisms using data from a long‐term food provisioning experiment on wild female banded mongooses (Mungos mungo). Our results show that maternal supplementation did not influence oxidative stress levels, or the production and survival of offspring. However, we found that two of the oxidative mechanisms co‐occur during reproduction. There was evidence of an oxidative challenge associated with reproduction that mothers attempted to mitigate by reducing damage levels during breeding. This mitigation is likely to be of crucial importance, as long‐term offspring survival was negatively impacted by maternal oxidative stress. This study demonstrates the value of longitudinal studies of wild animals in order to highlight the interconnected oxidative mechanisms that shape the cost of reproduction.

Oxidative Damage Is Influenced by Diet But Unaffected by Selection for Early Age of Oviposition in the Marula Fly, Ceratitis cosyra (Diptera: Tephritidae)

The expression of life-history traits, such as lifespan or reproductive effort, is tightly correlated with the amount and blend of macronutrients that individuals consume. In a range of herbivorous insects, consuming high protein to carbohydrate ratios (P:C) decreases lifespan but increases female fecundity. In other words, females face a resource-based trade-off between lifespan and fecundity. Redox metabolism may help mediate this trade-off, if oxidative damage is elevated by reproductive investment and if this damage, in turn, reduces lifespan. Here, we test how diets varying in P:C ratio affect oxidative damage and antioxidant protection in female and male of the marula fly, Ceratitis cosyra (Diptera: Tephritidae). We use replicated lines that have been subjected to experimental evolution and differ in their lifespan and reproductive scheduling. We predicted that high fecundity would be associated with high oxidative damage and reduced antioxidant defences, while longer lived flies would show reduced damage and elevated antioxidant defences. However, higher levels of oxidative damage were observed in long-lived control lines than selection lines, but only when fed the diet promoting lifespan. Flies fed diets promoting female fecundity (1:4 and 1:2 P:C) suffered greater oxidative damage to lipids than flies fed the best diet (0:1 P:C) for lifespan. Total antioxidant capacity was not affected by the selection regime or nutrition. Our results reiterate the importance of nutrition in affecting life-history traits, but suggest that in C. cosyra, reactive oxygen species play a minimal role in mediating dietary trade-offs between lifespan and reproduction.

Lycopene Supplementation to Serum-Free Maturation Medium Improves In Vitro Bovine Embryo Development and Quality and Modulates Embryonic Transcriptomic Profile

Bovine embryos are typically cultured at reduced oxygen tension to lower the impact of oxidative stress on embryo development. However, oocyte in vitro maturation (IVM) is performed at atmospheric oxygen tension since low oxygen during maturation has a negative impact on oocyte developmental competence. Lycopene, a carotenoid, acts as a powerful antioxidant and may protect the oocyte against oxidative stress during maturation at atmospheric oxygen conditions. Here, we assessed the effect of adding 0.2 μM lycopene (antioxidant), 5 μM menadione (pro-oxidant), and their combination on the generation of reactive oxygen species (ROS) in matured oocytes and the subsequent development, quality, and transcriptome of the blastocysts in a bovine in vitro model. ROS fluorescent intensity in matured oocytes was significantly lower in the lycopene group, and the resulting embryos showed a significantly higher blastocyst rate on day 8 and a lower apoptotic cell ratio than all other groups. Transcriptomic analysis disclosed a total of 296 differentially expressed genes (Benjamini–Hochberg-adjusted p < 0.05 and ≥ 1-log2-fold change) between the lycopene and control groups, where pathways associated with cellular function, metabolism, DNA repair, and anti-apoptosis were upregulated in the lycopene group. Lycopene supplementation to serum-free maturation medium neutralized excess ROS during maturation, enhanced blastocyst development and quality, and modulated the transcriptomic landscape.

Anoxia hormesis following overwintering diapause boosts bee survivorship and adult performance

Insect pollination is a crucial component of our ecosystems and biodiversity, but our reliance on this ecosystem service has much broader implications. We depend on these pollination services to produce materials and food. But insect pollinators, especially bees, are in strong decline due to a plethora of factors, least of which are environmental abiotic stressors like climate change. The alfalfa leafcutting bee, Megachile rotundata, is the world's most managed solitary bee and is particularly vulnerable to changes in temperature. This species spends up to ten months overwintering while being exposed to the lowest temperatures of winters and the hottest temperatures of late summer. This results in usage of energy reserves prematurely and asynchronous spring emergence with their food resource. To understand the stress response of these bees and potentially boost their performance, we applied a hormetic framework where bees were exposure to different doses of anoxia (the absence of oxygen) to trigger hormesis; a low-dose stimulatory response known to lower damage and improve performance. We used hormesis on immature bees as a post-winter treatment with the goal of improving springtime performance in adults. One hour of anoxia had no negative effect on adult springtime emergence and bees were quick to recover. These bees were more active than untreated bees, as resistant to starvation, and as long-lived. Higher exposure to anoxia (3 h) was found to be mildly hormetic and 6-h exposures were detrimental. Anoxia hormesis did not represent a significant cost on the energy reserve of overwintering bees but we found that the age at which anoxia is applied will affect the effectiveness of treatment. Our data suggest that anoxia hormesis is a viable intervention to improve springtime performance in overwintering bees.

Antioxidant capacity differs across social ranks and with ascension in males of a group-living fish

Animals that live in groups often form hierarchies in which an individual's behaviour and physiology varies based on their social rank. Occasionally, a subordinate can ascend into a dominant position and the ascending individual must make rapid behavioural and physiological adjustments to solidify their dominance. These periods of social transition and instability can be stressful and ascending individuals often incur large metabolic costs that could influence their oxidative status. Most previous investigations examining the link between oxidative status and the social environment have done so under stable social conditions and have evaluated oxidative status in a single tissue. Therefore, evaluations of how oxidative status is regulated across multiple tissues during periods of social flux would greatly enhance our understanding of the relationship between oxidative status and the social environment. Here, we assessed how antioxidant capacity in three tissues (brain, gonad, and muscle) varied among dominant, subordinate, and ascending males of the group-living cichlid fish, Neolamprologus pulcher. Antioxidant capacity in the brain and muscle of ascending males was intermediate to that of dominant (highest levels) and subordinate males (lowest levels) and correlated with differences in social and locomotor behaviours, respectively. Gonad antioxidant capacity was lower in ascending males than in dominant males. However, gonad antioxidant capacity was positively correlated with the size of ascending males' gonads suggesting that ascending males may increase gonad antioxidant capacity as they develop their gonads. Overall, our results highlight the widespread physiological consequences of social ascension and emphasize the importance of tissue-specific measures of oxidative status.

The Cost of Reproduction in a Cooperatively Breeding Mammal: Consequences of Seasonal Variation in Rainfall, Reproduction, and Reproductive Suppression

Biological investments, such as reproduction, are influenced by both biotic and abiotic factors and their interactions. The trade-off between reproduction and survival has been well established. Seasonally breeding species, therefore, may exhibit variations in these trade-offs, but there is a dearth of knowledge concerning this. This study investigated the physiological cost of reproduction (measured through oxidative stress) across seasons in the cooperatively breeding highveld mole-rat (Cryptomys hottentotus pretoriae), one of the few seasonal breeding mole-rats. Oxidative stress indicates elevated reactive oxygen species (ROS) levels, which can overwhelm antioxidant defences resulting in damaged proteins, lipids and DNA, which overall can reduce longevity and compromise reproduction. Oxidative markers such as total oxidant status (TOS-measure of total peroxides present), total antioxidant capacity (TAC), oxidative stress index (OSI), and malondialdehyde (MDA) are utilised to measure oxidative stress. In this study, breeding and non-breeding male (NBM) and female mole-rats were captured during the dry season (breeding period) and wet season (non-breeding period). There was an apparent cost of reproduction in the highveld mole-rat; however, the seasonality pattern to the cost of reproduction varied between the sexes. Breeding females (BFs) had significantly higher MDA during the breeding period/dry season in comparison to the non-breeding period/wet season; this is possibly a consequence of bearing and nursing offspring. Contrastingly, breeding males (BMs) showed increased oxidative damage in the non-breeding/wet season compared to the breeding/dry season, possibly due to increased activities of protecting their mating rights for the next breeding/dry season, but this was not significant. Interestingly, during the non-breeding period/wet season, non-breeding females (NBFs) are released from their reproductive suppression, which resulted in increases in TOS and OSI, which again indicated that just the mere ability to be able to breed results in a cost (oxidative stress). Therefore we can speculate that highveld mole-rats exhibited seasonal variation in redox balance brought about by variation in abiotic variables (e.g., rainfall), physiology and behaviour. We conclude that physiological changes associated with reproduction are sufficient to induce significant acute oxidative stress in the plasma of female highveld mole-rats, which become alleviated following transition to the non-breeding season/wet period suggesting a possible hormetic effect.

Early-life patterns of growth are linked to levels of phenotypic trait covariance and postfledging mortality across avian species

Life history studies have established that trade-offs between growth and survival are common both within and among species. Identifying the factor(s) that mediate this trade-off has proven difficult, however, especially at the among-species level. In this study, we examined a series of potentially interrelated traits in a community of temperate-zone passerine birds to help understand the putative causes and consequences of variation in early-life growth among species. First, we examined whether nest predation risk (a proven driver of interspecific variation in growth and development rates) was correlated with species-level patterns of incubation duration and nestling period length. We then assessed whether proxies for growth rate covaried with mean trait covariance strength (i.e., phenotypic correlations ( rp), which can be a marker of early-life stress) among body mass, tarsus length, and wing length at fledging. Finally, we examined whether trait covariance strength at fledging was related to postfledging survival. We found that higher nest predation risk was correlated with faster skeletal growth and that our proxies for growth corresponded with increased trait covariance strength ( rp), which subsequently, correlated with higher mortality in the next life stage (postfledging period). These results provide an indication that extrinsic pressures (nest predation) impact rates of growth, and that there are costs of rapid growth across species, expressed as higher mean rp and elevated postfledging mortality. The link between higher levels of trait covariance at fledging and increased mortality is unclear, but increased trait covariance strength may reflect reduced phenotypic flexibility (i.e., phenotypic canalization), which may limit an organism's capacity for coping with environmental or ecological variability.

Resistance and survival to extreme heat shows circadian and sex-specific patterns in A cavity nesting bee

The pollination services provided by insects have been a crucial part of evolution and survival for many species, including humans. For bees to be efficient pollinators they must survive the environmental insults they face daily. Thus, looking into the short- and long-term effects of heat exposure on bee performance provides us with a foundation for investigating how stress can affect insect pollination. Solitary bees are a great model for investigating the effects of environmental stress on pollinators because the vast majority of insect pollinator species are solitary rather than social. One of the most pervasive environmental stressors to insects is temperature. Here we investigated how a one-hour heat shock affected multiple metrics of performance in the alfalfa leafcutting bee, Megachile rotundata. We found that a short heat shock (1hr at 45°C) can delay adult emergence in males but not females. Bee pupae were rather resilient to a range of high temperature exposures that larvae did not survive. Following heat shock (1hr at 50°C), adult bees were drastically less active than untreated bees, and this reduction in activity was evident over several days. Heat shock also led to a decrease in bee survival and longevity. Additionally, we found a connection between starvation survival after heat shock and time of exposure, where bees exposed in the morning survived longer than those exposed in the afternoon, when they would normally experience heat shock in the field. These data suggest that there is an unexplored daily/circadian component to the stress response in bees likely similar to that seen in flies, nematodes, and plants which is constitutive or preemptive rather than restorative. Taken together our data indicate that single heat shock events have strong potential to negatively impact multiple life history traits correlated with reproduction and fitness.

Probiotics and gut microbiome - Prospects and challenges in remediating heavy metal toxicity

The gut microbiome, often referred to as "super organ", comprises up to a hundred trillion microorganisms, and the species diversity may vary from person to person. They perform a decisive role in diverse biological functions related to metabolism, immunity and neurological responses. However, the microbiome is sensitive to environmental pollutants, especially heavy metals. There is continuous interaction between heavy metals and the microbiome. Heavy metal exposure retards the growth and changes the structure of the phyla involved in the gut microbiome. Meanwhile, the gut microbiome tries to detoxify the heavy metals by altering the physiological conditions, intestinal permeability, enhancing enzymes for metabolizing heavy metals. This review summarizes the effect of heavy metals in altering the gut microbiome, the mechanism by which gut microbiota detoxifies heavy metals, diseases developed due to heavy metal-induced dysbiosis of the gut microbiome, and the usage of probiotics along with advancements in developing improved recombinant probiotic strains for the remediation of heavy metal toxicity.

Social instability influences rank-specific patterns of oxidative stress in a cichlid fish

In many animal societies, dominant individuals have priority access to resources. However, defending high rank can be costly, especially in unstable social hierarchies where there is more intense competition. Oxidative stress has been proposed as a potential cost of social dominance, but few studies have examined this cost in relation to social stability. We studied the cost of social dominance in the cichlid fish Astatotilapia burtoni by manipulating social stability among males in replicate naturalistic communities for 22 weeks. We found that our social stability treatment influenced status-specific patterns in 3 out of 6 measurements of oxidative stress. Specifically, dominant males experienced increased plasma oxidative damage (measured as reactive oxygen metabolites, ROMs) compared with subordinate males in stable hierarchies only. Subordinate males in unstable hierarchies had higher ROMs than their stable community counterparts, but we found no effect of social stability treatment for dominant males. However, dominant males tended to have reduced total antioxidant capacity (TAC) in the liver when compared with subordinate males in unstable hierarchies, suggesting that the cost of social dominance is higher in unstable hierarchies. There were no effects of status and treatment on gonad TAC, muscle TAC or oxidative DNA damage. We conclude that the stability of the social environment influences the relative cost of social dominance in a tissue- and marker-specific manner.

Molecular characterization of a catalase gene from the green peach aphid (Myzus persicae)

The green peach aphid, Myzus persicae (Sulzer), is a serious agricultural pest with a worldwide distribution. Catalase (CAT), which is encoded by the catalase (Cat) gene, is an extremely important antioxidant enzyme that plays a pivotal role in protecting cells against the toxic effects of hydrogen peroxide. The Cat gene has not been characterized in M. persicae; therefore, this study describes the identification of the Cat (MpCat) gene from M. persicae. MpCat contains an open reading frame of 1515 bp and encodes a MpCAT protein consisting of 504 amino-acid residues. MpCAT possesses features typical of other insect catalases, including 7 conserved amino acids involved in binding heme and 15 involved in binding nicotinamide adenine dinucleotide phosphate. Phylogenetic analysis showed that MpCAT was closely related to orthologs from other aphid species. MpCat consisted of nine exons and eight introns, and the number and insertion sites of introns are consistent with those of Cat genes from Acyrthosiphon pisum (Harris) and Aphis gossypii Glover. The mRNA transcripts of MpCat were detected at all tested developmental stages, with the highest mRNA level in alate adults. The expression of MpCat was significantly upregulated when M. persicae was exposed to low and high temperatures, ultraviolet radiation, Beauveria bassiana, and permethrin. The transcription of MpCat and the activity of catalase were suppressed by RNA interference, and knockdown of MpCat significantly reduced the survival rate in M. persicae under heat stress. The results provide valuable information for further study on the physiological functions of MpCat.

Invited review: Thermal effects on oxidative stress in vertebrate ectotherms

Human-induced climate change is occurring rapidly. Ectothermic organisms are particularly vulnerable to these temperature changes due to their reliance on environmental temperature. The extent of ectothermic thermal adaptation and plasticity in the literature is well documented; however, the role of oxidative stress in these processes needs more attention. Oxidative stress occurs when reactive oxygen species, generated mainly through aerobic respiration, overwhelm antioxidant defences and damage crucial biomolecules. The effects of oxidative damage include the alteration of life-history traits and reductions in whole-organism fitness. Here we review the literature addressing experimental temperature effects on oxidative stress in vertebrate ectotherms. Acute and acclimation temperature treatments produce distinctly different results and highlight the role of phylogeny and thermal adaptation in shaping oxidative stress responses. Acute treatments on organisms adapted to stable environments generally produced significant oxidative stress responses, whilst organisms adapted to variable conditions exhibited capacity to cope with temperature changes and mitigate oxidative stress. In acclimation treatments, the temperature treatments higher than optimal temperatures tended to produce significantly less oxidative stress than lower temperatures in reptiles, whilst in some eurythermal fish species, no oxidative stress response was observed. These results highlight the importance of phylogeny and adaptation to past environmental conditions for temperature-dependent oxidative stress responses. We conclude with recommendations on experimental procedures to investigate these phenomena with reference to thermal plasticity, adaptation and biogeographic variation that provide the most significant benefits to adaptable populations. These results have potential conservation ramifications as they may shed light on the physiological effects of temperature alterations in some vertebrate ectotherms.