Plasmid size determines adsorption to clay and breakthrough in a saturated sand column.

Horizontal gene transfer (HGT) is a major factor in the spread of antibiotic resistant genes (ARG). Transformation, one mode of HGT, involves the acquisition and expression of extracellular DNA (eDNA). eDNA in soils is degraded rapidly by extracellular nucleases.

The influence of incubation temperature on offspring traits varies across northern and southern populations of the American alligator ().

Maternal provisioning and the developmental environment are fundamental determinants of offspring traits, particularly in oviparous species. However, the extent to which embryonic responses to these factors differ across populations to drive phenotypic variation is not well understood. Here, we examine the contributions of maternal provisioning and incubation temperature to hatchling morphological and metabolic traits across four populations of the American alligator (), encompassing a large portion of the species' latitudinal range.

Association of size, climatic factors, and mercury body burdens with movement behavior in American alligators.

Animal movement behavior provides insight into organismal and ecological function. These functions are often disturbed by anthropogenic influences, such as urbanization and habitat fragmentation, yet the effects of long-term exposures to environmental contaminants on movement have yet to be examined. The long lifespans and broad diets of crocodilians often lead to bioaccumulation of persistent contaminants and confer a marked vulnerability to consequent physiological effects.

Epigenetic drift underlies epigenetic clock signals, but displays distinct responses to lifespan interventions, development, and cellular dedifferentiation.

Changes in DNA methylation with age are observed across the tree of life. The stereotypical nature of these changes can be modeled to produce epigenetic clocks capable of predicting chronological age with unprecedented accuracy. Despite the predictive ability of epigenetic clocks and their utility as biomarkers in clinical applications, the underlying processes that produce clock signals are not fully resolved, which limits their interpretability.

The rate of epigenetic drift scales with maximum lifespan across mammals.

Epigenetic drift or "disorder" increases across the mouse lifespan and is suggested to underlie epigenetic clock signals. While the role of epigenetic drift in determining maximum lifespan across species has been debated, robust tests of this hypothesis are lacking. Here, we test if epigenetic disorder at various levels of genomic resolution explains maximum lifespan across four mammal species.

Maternal provisioning interacts with incubation temperature to affect hatchling mercury exposure in an oviparous reptile.

The thermal environment experienced by developing embryos can influence the utilization of maternally provisioned resources. Despite being particularly consequential for oviparous ectotherms, these dynamics are largely unexplored within ecotoxicological frameworks. Here, we test if incubation temperature interacts with maternally transferred mercury to affect subsequent body burdens and tissue distributions of mercury in hatchling American alligators ().

Incubation temperature alters stripe formation and head colouration in American alligator hatchlings and is unaffected by estradiol-induced sex reversal.

Considerations of the impact climate change has on reptiles are typically focused on habitat change or loss, range shifts and skewed sex ratios in species with temperature-dependent sex determination. Here, we show that incubation temperature alters stripe number and head colouration of hatchling American alligators (Alligator mississippiensis). Animals incubated at higher temperatures (33.

Relationships between maternally-transferred mercury and hatchling development, behavior, and survival in the American alligator (Alligator mississippiensis).

Mercury is a toxic and pervasive environmental contaminant that can be transferred from mother to offspring during development. Consequences of maternally-transferred mercury have been observed in vertebrate taxa, including reduced clutch viability, reduced offspring size, and behavioral alterations. These sublethal effects have been assumed to decrease survivorship, though this is seldom assessed.

Integrating Mercury Concentrations in American Alligators (Alligator mississippiensis) with Hunter Consumption Surveys to Estimate Exposure Risk.

Mercury is a naturally occurring element but is also considered a widespread contaminant due to global anthropogenic activity. Even in moderate amounts, mercury (Hg) is an established neurotoxin and is associated with a range of adverse outcomes both in humans and wildlife. Humans in the United States are most commonly exposed to Hg through contaminated food or drinking water, and the consumption of game species, particularly those occupying higher trophic levels, has the potential to expose hunters to high concentrations of Hg.

Sex Determination and Ovarian Development in Reptiles and Amphibians: From Genetic Pathways to Environmental Influences.

Background: Reptiles and amphibians provide untapped potential for discovering how a diversity of genetic pathways and environmental conditions are incorporated into developmental processes that can lead to similar functional outcomes. These groups display a multitude of reproductive strategies, and whereas many attributes are conserved within groups and even across vertebrates, several aspects of sexual development show considerable variation.

Summary: In this review, we focus our attention on the development of the reptilian and amphibian ovary.

Acute Copper Toxicity Displays a Nonmonotonic Relationship with Age Across the Medaka (Oryzias latipes) Life Span.

The ability of an organism to cope with environmental stressors varies across the life span because of developmental stage-specific responses and age-related functional declines. In the present study, we examined the effect of age on acute copper toxicity in Japanese medaka (Oryzias latipes). We first determined the median lethal concentration (LC50) at 96 h for embryos, 7-day-old fry, and 6-month-old medaka.

Genome-wide DNA methylation patterns harbour signatures of hatchling sex and past incubation temperature in a species with environmental sex determination.

Conservation of thermally sensitive species depends on monitoring organismal and population-level responses to environmental change in real time. Epigenetic processes are increasingly recognized as key integrators of environmental conditions into developmentally plastic responses, and attendant epigenomic data sets hold potential for revealing cryptic phenotypes relevant to conservation efforts. Here, we demonstrate the utility of genome-wide DNA methylation (DNAm) patterns in the face of climate change for a group of especially vulnerable species, those with temperature-dependent sex determination (TSD).

Transcriptional networks underlying a primary ovarian insufficiency disorder in alligators naturally exposed to EDCs.

Interactions between the endocrine system and environmental contaminants are responsible for impairing reproductive development and function. Despite the taxonomic diversity of affected species and attendant complexity inherent to natural systems, the underlying signaling pathways and cellular consequences are mostly studied in lab models. To resolve the genetic and endocrine pathways that mediate affected ovarian function in organisms exposed to endocrine disrupting contaminants in their natural environments, we assessed broad-scale transcriptional and steroidogenic responses to exogenous gonadotropin stimulation in juvenile alligators (Alligator missippiensis) originating from a lake with well-documented pollution (Lake Apopka, FL) and a nearby reference site (Lake Woodruff, FL).

Development of DNA methylation-based epigenetic age predictors in loblolly pine (Pinus taeda).

Biological ageing is connected to life history variation across ecological scales and informs a basic understanding of age-related declines in organismal function. Altered DNA methylation dynamics are a conserved aspect of biological ageing and have recently been modelled to predict chronological age among vertebrate species. In addition to their utility in estimating individual age, differences between chronological and predicted ages arise due to acceleration or deceleration of epigenetic ageing, and these discrepancies are linked to disease risk and multiple life history traits.

Quantifying Circulating IgY Antibody Responses against Select Opportunistic Bacterial Pathogens and Correlations with Body Condition Factors in Wild American Alligators, .

Little is known about the disease ecology of American alligators (), and especially how they respond immunologically to emerging infectious diseases and zoonotic pathogens. In this study, we examined serum samples collected from wild alligators in Florida (2010-2011) and South Carolina (2011-2012, 2014-2017) for antibody responses to multiple bacteria. Immunoglobulin Y (IgY) was purified from serum to generate a mouse monoclonal antibody (mAb AMY-9) specific to the IgY heavy chain.

Transient Copper Exposure During Embryogenesis and Temperature Affect Developmental Rate, Survival, and Fin Regeneration in Japanese Medaka (Oryzias latipes).

Combined environmental stressors that an organism experiences can have both immediate and lasting consequences. In the present study, we exposed Japanese medaka (Oryzias latipes) embryos to sublethal copper sulfate (CuSO ; 0, 10, and 100 ppb) in combination with different rearing temperatures (27, 30, and 33 °C) to assess acute and latent effects on development, growth, and regenerative capacity. Embryos exposed to CuSO and/or higher temperatures hatched significantly earlier.

Exposure to ionizing radiation disrupts normal epigenetic aging in Japanese medaka.

Alterations to the epigenome are a hallmark of biological aging and age-dependent patterning of the DNA methylome ("epigenetic aging") can be modeled to produce epigenetic age predictors. Rates of epigenetic aging vary amongst individuals and correlate to the onset of age-related disease and all-cause mortality. Yet, the origins of epigenetic-to-chronological age discordance are not empirically resolved.

Incubation Temperature and Maternal Resource Provisioning, but Not Contaminant Exposure, Shape Hatchling Phenotypes in a Species with Temperature-Dependent Sex Determination.

AbstractThe environment experienced during embryonic development is a rich source of phenotypic variation, as environmental signals have the potential to both inform adaptive plastic responses and disrupt normal developmental programs. Environment-by-embryo interactions are particularly consequential for species with temperature-dependent sex determination, a mode of sex determination common in non-avian reptiles and fish, in which thermal cues during a discrete period of development drive the formation of either an ovary or a testis. Here we examine the impact of thermal variation during incubation in combination with developmental exposure to a common endocrine-disrupting contaminant on fitness-related hatchling traits in the American alligator (), a species with temperature-dependent sex determination.

Intrinsic and extrinsic factors interact during development to influence telomere length in a long-lived reptile.

The mechanisms connecting environmental conditions to plasticity in biological aging trajectories are fundamental to understanding individual variation in functional traits and life history. Recent findings suggest that telomere biology is especially dynamic during early life stages and has long-term consequences for subsequent reproduction and survival. However, our current understanding is mostly derived from studies investigating ecological and anthropogenic factors separately, leaving the effects of complex environmental interactions unresolved.

Post-Transcriptional Mechanisms Respond Rapidly to Ecologically Relevant Thermal Fluctuations During Temperature-Dependent Sex Determination.

An organism's ability to integrate transient environmental cues experienced during development into molecular and physiological responses forms the basis for adaptive shifts in phenotypic trajectories. During temperature-dependent sex determination (TSD), thermal cues during discrete periods in development coordinate molecular changes that ultimately dictate sexual fate and contribute to patterns of inter- and intra-sexual variation. How these mechanisms interface with dynamic thermal environments in nature remain largely unknown.

Assessing the Ability of Developmentally Precocious Estrogen Signaling to Recapitulate Ovarian Transcriptomes and Follicle Dynamics in Alligators from a Contaminated Lake.

Background: Concern has grown in recent decades over anthropogenic contaminants that interfere with the functioning of endocrine hormones. However, mechanisms connecting developmental processes to pathologies associated with endocrine-disrupting chemical (EDC) exposure are poorly understood in naturally exposed populations.

Objectives: We sought to ) characterize divergence in ovarian transcriptomic and follicular profiles between alligators originating from a historically EDC-contaminated site, Lake Apopka, and a reference site; ) test the ability of developmentally precocious estrogen exposure to recapitulate site-associated patterns of divergence; and ) test whether treatment with exogenous follicle-stimulating hormone (FSH) is capable of rescuing phenotypes associated with contaminant exposure and/or embryonic estrogen treatment.

Is CpG Density the Link between Epigenetic Aging and Lifespan?

The genetic mechanisms contributing to lifespan variation remain unresolved. Based on recent conceptual advances in our understanding of epigenetic potential and the relocalization of chromatin modifiers (RCM), we hypothesize that increased CpG density is protective against age-related erosion of the epigenetic landscape and may explain interspecific variation in lifespan.

Chronic low dose irradiation alters hepatic transcriptional profiles, but not global DNA methylation in medaka (Oryzias latipes).

Ionizing radiation (IR) resulting from both natural and anthropogenic sources is ubiquitous throughout the environment. Historically, studies on the biological impacts of radiation primarily focused on responses to acute doses of radiation, with little advancement in our understanding of environmentally relevant exposures. Epigenetic mechanisms are capable of mediating organismal responses to environmental stressors and DNA methylation plays important roles in gene regulation and promoting chromosomal stability.

Spatial and temporal variation in nest temperatures forecasts sex ratio skews in a crocodilian with environmental sex determination.

Species displaying temperature-dependent sex determination (TSD) are especially vulnerable to the effects of a rapidly changing global climate due to their profound sensitivity to thermal cues during development. Predicting the consequences of climate change for these species, including skewed offspring sex ratios, depends on understanding how climatic factors interface with features of maternal nesting behaviour to shape the developmental environment. Here, we measure thermal profiles in 86 nests at two geographically distinct sites in the northern and southern regions of the American alligator's () geographical range, and examine the influence of both climatic factors and maternally driven nest characteristics on nest temperature variation.

G-protein signaling is required for increasing germline stem cell division frequency in response to mating in Drosophila males.

Adult stem cells divide to renew the stem cell pool and replenish specialized cells that are lost due to death or usage. However, little is known about the mechanisms regulating how stem cells adjust to a demand for specialized cells. A failure of the stem cells to respond to this demand can have serious consequences, such as tissue loss, or prolonged recovery post injury.