Developmental Thermal Conditioning Regulates Oxidative State and Beak Coloration in Response to Thermal Stressors in Adulthood.

AbstractAt certain intensities and durations, environmental stressors during development can result in changes in physiology that prepare organisms for future stressful conditions. Such plasticity can allow organisms to maintain good condition when confronted with a poor environment, potentially conferring an advantage in fitness. However, the physiological changes underlying these adaptive phenotypic adjustments are understudied.

Early life thermal conditioning alters heat-shock protein expression in response to an adult thermal stressor.

Developmental environmental stressors can have instructive effects on an organism's phenotype. This developmental plasticity can prepare organisms for potentially stressful future environments, circumventing detrimental effects on fitness. However, the physiological mechanisms underlying such adaptive plasticity are understudied, especially in vertebrates.

Exposure to ecologically relevant estrogen levels do not influence morphology or immune parameters in hatchling American alligators (Alligator mississippiensis).

Human activity has increased concentrations of endocrine-disrupting contaminants (EDCs) in many ecological systems. Many EDCs are xenoestrogens, which imitate naturally derived estrogen like estradiol 17-β (E2). These pollutants can critically affect a broad range of biological functions, particularly in organisms inhabiting aquatic environments.

Xenobiotic estradiol-17ß alters gut microbiota of hatchling American alligators (Alligator mississippiensis).

Environmental oestrogens pose serious concerns for ecosystems through their effects on organismal survival and physiology. The gut microbiome is highly vulnerable to environmental influence, yet the effects of oestrogens on gut homeostasis are unknown because they are poorly studied in wildlife populations. To determine the influence of environmental oestrogens (i.

Male gopher tortoise (Gopherus polyphemus) concentration-dependent social responses to diluted mental gland pheromones.

In complex terrestrial environments, chemical signals can be the most important sensory modality for locating conspecifics for potential mating opportunities, especially in spatially segregated populations or habitats. Organisms must evolve chemical signals to maximize the efficacy of conveying information, particularly in creating trails or mate-choice cues. Long-distance transmission of chemical signals may be an increasingly important management concern for small and fractured populations or potentially threatened species, such as gopher tortoises in the southeastern U.

Tissue Distribution of Mercury in the Bodies of Wild American Alligators (Alligator mississippiensis) from a Coastal Marsh in Louisiana (USA).

Total mercury (THg) concentrations were measured in wild alligators inhabiting a coastal marsh in southern Louisiana, to determine the tissue distribution of THg among various body organs and tissue compartments. Concentrations of THg in claws and dermal tail scutes were compared to those in blood, brain, gonad, heart, kidney, liver, and skeletal muscle to determine if the former tissues, commonly available by non-lethal sampling, could be used as measures of body burdens in various internal organs. Mercury was found in all body organs and tissue compartments.

Unveiling the Gut Microbiota and Resistome of Wild Cotton Mice, , from Heavy Metal- and Radionuclide-Contaminated Sites in the Southeastern United States.

The prevalence of antibiotic resistance genes (ARGs) can be driven by direct selection from antibiotic use and indirect selection from substances such as heavy metals (HMs). While significant progress has been made to characterize the influence of HMs on the enrichment and dissemination of ARGs in the environment, there is still much we do not know. To fill this knowledge gap, we present a comprehensive analysis of gut bacteria associated with wild cotton mice (Peromyscus gossypinus) trapped from several areas affected by legacies of HM and radionuclide contamination.

Behavioural discrimination of male mental gland secretions of the gopher tortoise (Gopherus polyphemus) by both sexes.

Chemical communication is important for mate choice, especially at long distances in fragmented populations. The gopher tortoise is a social species that is threatened in the southeast U.S.

Microbiota of Four Tissue Types in American Alligators (Alligator mississippiensis) Following Extended Dietary Selenomethionine Exposure.

Selenium represents an essential trace nutrient that is necessary for biological functions. Deficiencies can induce disease, but excess can induce toxicity. Selenium deficiency is a major concern in underdeveloped countries, while also posing as a toxic pollutant in waterways surrounding landfills, agricultural areas, and fossil fuel production sites.

Identification and characterization of microRNAs (miRNAs) and their transposable element origins in the saltwater crocodile, Crocodylus porosus.

MicroRNAs (miRNAs) are 18-24 nucleotide regulatory RNAs. They are involved in the regulation of genetic and biological pathways through post transcriptional gene silencing and/or translational repression. Data suggests a slow evolutionary rate for the saltwater crocodile (Crocodylus porosus) over the past several million years when compared to birds, the closest extant relatives of crocodilians.

Co-occurrence of antibiotic, biocide, and heavy metal resistance genes in bacteria from metal and radionuclide contaminated soils at the Savannah River Site.

Contaminants such as heavy metals may contribute to the dissemination of antimicrobial resistance (AMR) by enriching resistance gene determinants via co-selection mechanisms. In the present study, a survey was performed on soils collected from four areas at the Savannah River Site (SRS), South Carolina, USA, with varying contaminant profiles: relatively pristine (Upper Three Runs), heavy metals (Ash Basins), radionuclides (Pond B) and heavy metal and radionuclides (Tim's Branch). Using 16S rRNA gene amplicon sequencing, we explored the structure and diversity of soil bacterial communities.

Adapterama II: universal amplicon sequencing on Illumina platforms (TaggiMatrix).

Next-generation sequencing (NGS) of amplicons is used in a wide variety of contexts. In many cases, NGS amplicon sequencing remains overly expensive and inflexible, with library preparation strategies relying upon the fusion of locus-specific primers to full-length adapter sequences with a single identifying sequence or ligating adapters onto PCR products. In , we presented universal stubs and primers to produce thousands of unique index combinations and a modifiable system for incorporating them into Illumina libraries.

Adapterama I: universal stubs and primers for 384 unique dual-indexed or 147,456 combinatorially-indexed Illumina libraries (iTru & iNext).

Massively parallel DNA sequencing offers many benefits, but major inhibitory cost factors include: (1) start-up (i.e., purchasing initial reagents and equipment); (2) buy-in (i.

Adapterama III: Quadruple-indexed, double/triple-enzyme RADseq libraries (2RAD/3RAD).

Molecular ecologists frequently use genome reduction strategies that rely upon restriction enzyme digestion of genomic DNA to sample consistent portions of the genome from many individuals (e.g., RADseq, GBS).

Examining the Effects of Chronic Selenium Exposure on Traditionally Used Stress Parameters in Juvenile American Alligators (Alligator mississippiensis).

Environmental contaminants, such as the trace element selenium (Se), are a continuing concern to species worldwide due to their potential pathophysiological effects, including their influence on the stress response mediated through glucocorticoids (GCs; stress hormones). Environmental concentrations of Se are increasing due to anthropogenic activities, including the incomplete combustion of coal and subsequent disposal of coal combustion wastes. However, most studies examining how Se affects GCs have been focused on lower trophic organisms.

Quantification of plasma corticosterone in juvenile farmed saltwater crocodiles (Crocodylus porosus) using current Australian Code of Practice guidelines.

Saltwater crocodiles (Crocodylus porosus) across three size categories (hatchlings, grower and harvest-size) were repeatedly blood sampled on two farms in the Northern Territory, Australia to determine reference plasma corticosterone (CORT; crocodilian stress hormone) levels. The mean CORT values for hatchlings (<1 year old), growers (1-3 years) and harvest-size individuals (2 + years) were 1.65 ± 0.

Sex-Specific Effects of Incubation Temperature on Embryonic Development of Zebra Finch (Taeniopygia guttata) Embryos.

In oviparous species, the embryonic environment-particularly temperature-can alter phenotype and survival of an individual by affecting its size as well as its metabolic rate. Previous studies have shown that incubation temperatures can affect sex ratio in birds; specifically, low incubation temperatures were shown to produce a male-biased sex ratio in zebra finches (Taeniopygia guttata) possibly because of a higher pre- or postnatal mortality rate in females. We hypothesized that sexes respond differently to suboptimal incubation temperature, leading to a male-biased sex ratio.

Corticosterone in American alligator (Alligator mississippiensis) tail scutes: Evaluating the feasibility of using unconventional samples for investigating environmental stressors.

Baseline plasma corticosterone (CORT) concentrations have been widely used to investigate the effects of stressors in wild and captive crocodilians. However, collecting baseline plasma CORT samples from wild crocodilians may be particularly difficult due to the capture and handling protocols used for large individuals. Thus, it may prove beneficial to use recently modified techniques for extracting CORT deposited in keratinized and non-keratinized tissues to better quantify the effects of long-term stress in crocodilians.

Early stress priming and the effects on fitness-related traits following an adult stress exposure.

Developmental stressors can have strong effects that persist well into adulthood, and are generally seen as detrimental. However, recent work suggests that a mild developmental stressor can have beneficial effects by preparing the organism to better withstand negative impacts when exposed to high levels of the stressor later in life, also known as a conditioning hormesis. Still, little is known about the influence of such hormetic effects on fitness-related measures.

Dietary Selenomethionine Administration and Its Effects on the American Alligator (Alligator mississippiensis): Oxidative Status and Corticosterone Levels.

Selenium (Se) is an essential nutrient which in excess causes toxicity. The disposal of incompletely combusted coal, which often is rich in Se, into aquatic settling basins is increasing the risk of Se exposure worldwide. However, very few studies have looked at the physiological effects of Se exposure on long-lived, top trophic vertebrates, such as the American alligator (Alligator mississippiensis).

No Effect of Lifelong Methylmercury Exposure on Oxidative Status in Zebra Finches (Taeniopygia guttata): A Demonstration of Methylmercury-Induced Selection?

Songbirds exposed to methylmercury (MeHg) often exhibit reduced reproductive success and cognitive abilities. To better understand whether oxidative stress plays a role, we dosed zebra finches (Taeniopygia guttata) with a contaminated (1.2 ppm MeHg-cysteine) or control diet for their entire lives, including during development in the egg.

Effects of selenium exposure on the hematology, innate immunity, and metabolic rate of yellow-bellied sliders (Trachemys scripta scripta).

Selenium (Se) is a naturally occurring essential element that can be toxic to vertebrates at high concentrations. Despite studies that have documented that wild reptile species can accumulate copious amounts of Se, little is known regarding specific toxicologic effects of Se. In this study, 70 juvenile yellow-bellied sliders (Trachemys scripta scripta) were exposed to one of three seleno-L-methionine (SetMet) treatments (control, n = 24; 15 mg/kg, n = 23; and 30 mg/kg, n = 23) via weekly oral gavage for 5 weeks.

Accumulation of coal combustion residues and their immunological effects in the yellow-bellied slider (Trachemys scripta scripta).

Anthropogenic activities such as industrial processes often produce copious amounts of contaminants that have the potential to negatively impact growth, survival, and reproduction of exposed wildlife. Coal combustion residues (CCRs) represent a major source of pollutants globally, resulting in the release of potentially harmful trace elements such as arsenic (As), cadmium (Cd), and selenium (Se) into the environment. In the United States, CCRs are typically stored in aquatic settling basins that may become attractive nuisances to wildlife.

Dietary Selenomethionine Administration in the American Alligator (Alligator mississippiensis): Hepatic and Renal Se Accumulation and Its Effects on Growth and Body Condition.

Selenium (Se) is an essential trace nutrient, but in excess, it can induce toxicity. Incomplete combustion of coal produces coal combustion wastes, which are enriched in Se and often disposed of in aquatic basins. While a multitude of studies have investigated Se accumulation in vertebrates, few studies have examined its effects on longer-lived top trophic carnivores, such as the American alligator (Alligator mississippiensis).

Chronic Ingestion of Coal Fly-Ash Contaminated Prey and Its Effects on Health and Immune Parameters in Juvenile American Alligators (Alligator mississippiensis).

Coal-burning power plants supply approximately 37 % of the electricity in the United States. However, incomplete combustion produces ash wastes enriched with toxic trace elements that have historically been disposed of in aquatic basins. Organisms inhabiting such habitats may accumulate these trace elements; however, studies investigating the effects on biota have been primarily restricted to shorter-lived, lower-trophic organisms.