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•Wild birds are exposed to a suite of contaminants that can affect development.•Early life contaminant exposure can affect future survival/reproduction.•Most early-life toxicological ...research in birds utilizes precocial domestic species.•More research is needed on ecologically relevant contaminant concentrations.•Future research should evaluate early life effects on altricial and wild species.
The plight of wild birds is becoming critical due to exposure to environmental contaminants. Although laboratory studies have provided insights into the developmental effects of chemical exposures, less is known about the adverse effects of environmental chemicals in developing wild birds. Early life stages are critical windows during which long-term organization of physiological, behavioral, and neurological systems can occur. Thus, contaminant exposure at early life stages can directly influence survival and reproductive success, with consequences for population stability and resilience in wild species. This review synthesizes existing knowledge regarding both short- and long-term effects of early-life exposure to widespread contaminants in birds. We focus especially on wild birds and on contaminants of concern within the Gulf of Mexico as an example of a habitat under anthropogenic stress from exposure to a complex mixture of chemicals and changing land uses that exacerbate existing vulnerabilities of wildlife in this region. Chemical contaminants for discussion in this review are based on avian mortality records from the Wildlife Health Information Sharing Partnership (WHISPers) database and on additional review of the literature regarding avian contaminants of concern for the northern Gulf of Mexico, and include oil and associated polycyclic aromatic hydrocarbons, dioxin and dioxin-like compounds, flame retardants, pesticides, heavy metals, and plastics. We provide an overview of effects in bird species at both the pre-hatching and post-hatching early life stages, discuss differences in sensitivities by route of exposure, life stage, and life history, and provide recommendations for future research. We find that additional research is needed on altricial species, post-hatching early-life exposure, long-term effects, and on ecologically relevant contaminant concentrations and routes of exposure. Given the increasing frequency and intensity of anthropogenic stressors encountered by wild animals, understanding both lethal and sublethal impacts of contaminants on the health of individuals and populations will be critical to inform restoration, management, and mitigation efforts.
Extracellular vesicles (EVs) secreted by the epididymal epithelium transfer to spermatozoa key proteins that are essential in promoting motility and subsequent fertilization success. Using the ...domestic cat model, the objectives were to (1) characterize and compare protein content of EVs between segments of the epididymis, and (2) compare EV protein compositions between normo- and teratospermic individuals (producing >60% of abnormal spermatozoa). Epididymal EVs from adult cats were isolated and assessed via liquid chromatography tandem MS. Both male types shared 3008 proteins in total, with 98 and 20 EV proteins unique to normospermic and teratospermic males, respectively. Expression levels of several proteins changed between epididymal segments in both male types. Several proteins in both groups were related to sperm motility (e.g. hexokinase 1, adenylate kinase isoenzyme) and zona pellucida or oolemma binding (e.g. disintegrin and metalloproteinase domain proteins, zona binding proteins 1 and 2). Interestingly, seven cauda-derived EV proteins trended downward in teratospermic compared with normospermic males, which may relate to poor sperm quality. Collective results revealed, for the first time, EV proteins related to sequential sperm maturation with differences observed between normospermic and teratospermic individuals.
Abstract Endocrine disrupting chemicals (EDCs) exert hormone-like activity in vertebrates and exposure to these compounds may induce both short- and long-term deleterious effects including functional ...alterations that contribute to decreased reproduction and fitness. An overview of the effects of a number of EDCs, including androgenic and estrogenic compounds, will be considered. Many studies have been conducted in the precocial Japanese quail, which provides an excellent avian model for testing these compounds. Long-term impacts have also been studied by raising a subset of animals through maturation. The EDCs examined included estradiol, androgen active compounds, soy phytoestrogens, and atrazine. Effects on behavior and hypothalamic neuroendocrine systems were examined. All EDCs impaired reproduction, regardless of potential mechanism of action. Male sexual behavior proved to be a sensitive index of EDC exposure and embryonic exposure to a variety of EDCs consistently resulted in impaired male sexual behavior. Several hypothalamic neural systems proved to be EDC responsive, including arginine vasotocin (VT), catecholamines, and gonadotropin releasing hormone system (GnRH-I). Finally, EDCs are known to impact both the immune and thyroid systems; these effects are significant for assessing the overall impact of EDCs on the fitness of avian populations. Therefore, exposure to EDCs during embryonic development has consequences beyond impaired function of the reproductive axis. In conclusion, behavioral alterations have the advantage of revealing both direct and indirect effects of exposure to an EDC and in some cases can provide a valuable clue into functional deficits at different physiological levels.
Emergence of avian influenza viruses with high lethality to humans, such as the currently circulating highly pathogenic A(H5N1) (emerged in 1996) and A(H7N9) cause serious concern for the global ...economic and public health sectors. Understanding the spatial and temporal interface between wild and domestic populations, from which these viruses emerge, is fundamental to taking action. This information, however, is rarely considered in influenza risk models, partly due to a lack of data. We aim to identify areas of high transmission risk between domestic poultry and wild waterfowl in China, the epicenter of both viruses. Two levels of models were developed: one that predicts hotspots of novel virus emergence between domestic and wild birds, and one that incorporates H5N1 risk factors, for which input data exists. Models were produced at 1 and 30 km spatial resolution, and two temporal seasons. Patterns of risk varied between seasons with higher risk in the northeast, central-east, and western regions of China during spring and summer, and in the central and southeastern regions during winter. Monte-Carlo uncertainty analyses indicated varying levels of model confidence, with lowest errors in the densely populated regions of eastern and southern China. Applications and limitations of the models are discussed within.
Abstract As more comparative data become available, it is clear that the process of aging has fundamental similarities across classes of vertebrates. Birds provide a fascinating collection of species ...because of the considerable range in reproductive lifespan and variation in reproductive strategies that often relate to lifespan. One fascinating aspect of the comparative biology of aging in different avian species is the conserved mechanisms that appear very similar to those observed in mammals. Despite marked differences in sexual differentiation and reproductive function, including a single functional ovary and the internal testes, there appears to be remarkable similarity in elements of neuroendocrine aging and their end results. Furthermore, although beyond the scope of this review, the intense endocrine and energetic demands on many species of temperate zone birds for long migration and the accompanying seasonal alterations in endocrine responses add an additional layer of complexity in understanding aging. It is the purpose of this review to focus on neuroendocrine changes that accompany aging in a short-lived bird, with mention of some of the available data in field birds and long-lived species. Unfortunately, few neuroendocrine data are available for these long-lived avian species. It would be very interesting to determine if these long-lived birds somehow manage to delay the cascade of changes that contribute to the demise of metabolic and reproductive endocrine function. This review will also attempt to integrate the time-related events that occur in the responses of the hypothalamus and the gonads, especially relative to the neuroregulatory systems that have been implicated in the age-related decline in reproductive function. Finally, emerging areas of interest will be considered in the context of future research areas.
A fundamental understanding of the impact of petrochemicals and other stressors on marine biodiversity is critical for effective management, restoration, recovery, and mitigation initiatives. As ...species-specific information on levels of petrochemical exposure and toxicological response are lacking for the majority of marine species, a trait-based assessment to rank species vulnerabilities to petrochemical activities in the Gulf of Mexico can provide a more comprehensive and effective means to prioritize species, habitats, and ecosystems for improved management, restoration and recovery. To initiate and standardize this process, we developed a trait-based framework, applicable to a wide range of vertebrate and invertebrate species, that can be used to rank relative population vulnerabilities of species to petrochemical activities in the Gulf of Mexico. Through expert consultation, 18 traits related to likelihood of exposure, individual sensitivity, and population resilience were identified and defined. The resulting multi-taxonomic petrochemical vulnerability framework can be adapted and applied to a wide variety of species groups and geographic regions. Additional recommendations and guidance on the application of the framework to rank species vulnerabilities under specific petrochemical exposure scenarios, management needs or data limitations are also discussed.
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•Ecological and life-history traits can inform species’ relative vulnerabilities to threats.•Eighteen traits were identified to estimate petrochemical exposure, individual sensitivities and population resilience.•The resulting framework is applicable to multiple marine taxa and petrochemical exposure scenarios.
Recent studies from our laboratories and others suggest that calorie restriction (CR) may benefit Alzheimer's disease (AD) by preventing amyloid-beta (Abeta) neuropathology in the mouse models of AD. ...Moreover, we found that promotion of the NAD+-dependent SIRT1 mediated deacetylase activity, a key regulator in CR extension of life span, may be a mechanism by which CR influences AD-type neuropathology. In this study we continued to explore the role of CR in AD-type brain amyloidosis in Squirrel monkeys (Saimiri sciureus). Monkeys were maintained on the normal and CR diets throughout the entire lifespan until they died of natural causes. We found that 30% CR resulted in reduced contents of Abeta1-40 and Abeta1-42 peptides in the temporal cortex of Squirrel monkeys, relative to control (CON) fed monkeys. The decreased contents of cortical Abeta peptide inversely correlated with SIRT1 protein concentrations in the same brain region; no detectable change in total full-length amyloid-beta protein precursor (AbetaPP) level was found. Most interestingly, we found that 30% CR resulted in a select elevation of alpha- but not beta- or gamma- secretase activity which coincided with decreased ROCK1 protein content in the same brain region, relative to CON group. Collectively, the study suggests that investigation of the role of CR in non-human primates may provide a valuable approach for further clarifying the role of CR in AD.
Estrogens are neuroprotective and, thus, potentially useful for the therapy of Alzheimer's disease; however, clinical use of hormone therapy remains controversial due to adverse peripheral effects. ...The goal of this study was to investigate the benefits of treatment with 10beta,17beta-dihydroxyestra-1,4-dien-3-one (DHED), a brain-selective prodrug of 17beta-estradiol, in comparison with the parent hormone using APPswe/PS1dE9 double transgenic mice to model the pathology of the disease. Ovariectomized and intact females were continuously treated with vehicle, 17beta-estradiol, or DHED via subcutaneous osmotic pumps from 6 to 8months of age. We confirmed that this prolonged treatment with DHED did not stimulate uterine tissue, whereas 17beta-estradiol treatment increased uterine weight. Amyloid precursor protein decreased in both treatment groups of intact, but not in ovariectomized double transgenic females in which ovariectomy already decreased the expression of this protein significantly. However, reduced brain amyloid-beta peptide levels could be observed for both treatments. Consequently, double-transgenic ovariectomized and intact mice had higher cognitive performance compared to untreated control animals in response to both estradiol and DHED administrations. Overall, the tested brain-selective 17beta-estradiol prodrug proved to be an effective early-stage intervention in an Alzheimer's disease-relevant mouse model without showing systemic impact and, thus, warrants further evaluation as a potential therapeutic candidate. * .Treatment of AD-dtg mice with a brain-selective 17beta-estradiol (DHED) decreased APP * DHED treatment reduced brain amyloid-beta peptide levels * DHED-treated AD-dtg mice had improved cognitive performance * DHED treatment faithfully replicated positive effects observed for 17beta-estradiol * DHED did not stimulate uterine tissue, whereas 17beta-estradiol treatment did.
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