Publications by authors named "Robert B Page"

Introduction: COVID-19 has emerged as a highly contagious and debilitating disease caused by the SARS-CoV-2 virus and has claimed the lives of over 7.7 million people worldwide. Bacterial co-infections are one of many co-morbidities that have been suggested to impact the outcome of COVID-19 in patients.

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Development is a process that occurs over time, but defects are often scored at the end point of the process being studied. We are interested in understanding the molecular basis of gonad development in and have used the Distal Tip Cell marker to develop a larval size model of gonad growth. We found that gonad length demonstrates two distinct phases relative to larval length, with a breakpoint in mid-L3 stage.

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Climate change poses several challenges to biological communities including changes in the frequency of encounters between closely related congeners as a result of range shifts. When climate change leads to increased hybridization, hybrid dysfunction or genetic swamping may increase extinction risk-particularly in range-restricted species with low vagility. The Peaks of Otter Salamander, , is a fully terrestrial woodland salamander that is restricted to ~18 km of ridgeline in the mountains of southwestern Virginia, and its range is surrounded by the abundant and widespread Eastern Red-backed Salamander, .

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Invasive species are a major threat to global biodiversity. The US state of Florida is especially susceptible to the spread of exotic reptiles due to its subtropical climate, disturbed habitats, and robust pet trade. The Argentine black-and-white tegu (Salvator merianae) is a large, omnivorous lizard currently established in two different regions of Southern Florida.

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Article Synopsis
  • The red-backed salamander has been a key species for research in ecology and evolution, but extending genetic studies to less-explored populations has posed challenges due to significant genetic differences across its range.
  • Through 454 pyrosequencing, researchers discovered numerous microsatellite loci and tested these in populations from Virginia, Pennsylvania, and Ohio, identifying polymorphic loci that could aid in understanding population genetics.
  • The study found low genetic diversity in South Bass Island compared to other sites, but indicated that isolated populations aren't inbred and highlighted genetic clusters linked to geographic regions, enhancing knowledge of genetic variation in this species.
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Invasive species are widely recognized as important drivers of the ongoing biodiversity crisis. The US state of Florida is especially susceptible to the proliferation of invasive reptiles, and nonnative lizards currently outnumber native lizard species. At present, there are 3 documented breeding populations of the Nile monitor (Varanus niloticus) in different regions of Southern Florida, and these populations are considered potential dangers to threatened, fossorial endemics, such as burrowing owls, American crocodiles, and gopher tortoises.

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Glyceollins (Glys), produced by soy plants in response to stress, have anti-estrogenic activity in breast and ovarian cancer cell lines in vitro and in vivo. In addition to known anti-estrogenic effects, Gly exhibits mechanisms of action not involving estrogen receptor (ER) signaling. To date, effects of Gly on gene expression in the brain are unknown.

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Very little is known about genetic factors that regulate life history transitions during ontogeny. Closely related tiger salamanders (Ambystoma species complex) show extreme variation in metamorphic timing, with some species foregoing metamorphosis altogether, an adaptive trait called paedomorphosis. Previous studies identified a major effect quantitative trait locus (met1) for metamorphic timing and expression of paedomorphosis in hybrid crosses between the biphasic Eastern tiger salamander (Ambystoma tigrinum tigrinum) and the paedomorphic Mexican axolotl (Ambystoma mexicanum).

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Relative expression quantitative real-time polymerase chain reaction (RT-qPCR) experiments are a common means of estimating transcript abundances across biological groups and experimental treatments. One of the most frequently used expression measures that results from such experiments is the relative expression ratio (RE), which describes expression in experimental samples (i.e.

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Microarray analysis is widely used to identify transcriptional changes associated with genetic perturbation or signaling events. Here we describe its application in the identification of plant transcription factor target genes with emphasis on the design of suitable DNA constructs for controlling TF activity, the experimental setup, the statistical analysis of the microarray data, and the validation of target genes.

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Background: The Mexican axolotl (Ambystoma mexicanum) is considered a hopeful monster because it exhibits an adaptive and derived mode of development - paedomorphosis - that has evolved rapidly and independently among tiger salamanders. Unlike related tiger salamanders that undergo metamorphosis, axolotls retain larval morphological traits into adulthood and thus present an adult body plan that differs dramatically from the ancestral (metamorphic) form. The basis of paedomorphic development was investigated by comparing temporal patterns of gene transcription between axolotl and tiger salamander larvae (Ambystoma tigrinum tigrinum) that typically undergo a metamorphosis.

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Anuran (frog) metamorphosis has long-served as a model of how thyroid hormones regulate post-embryonic development in vertebrates. However, comparatively little is known about urodele (salamander) metamorphosis. We conducted a detailed time-course study of induced metamorphosis in the Mexican axolotl (Ambystoma mexicanum) that probed metamorphic changes in morphology and gene expression in the skin.

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Background: Microarray analysis and 454 cDNA sequencing were used to investigate a centuries-old problem in regenerative biology: the basis of nerve-dependent limb regeneration in salamanders. Innervated (NR) and denervated (DL) forelimbs of Mexican axolotls were amputated and transcripts were sampled after 0, 5, and 14 days of regeneration.

Results: Considerable similarity was observed between NR and DL transcriptional programs at 5 and 14 days post amputation (dpa).

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Background: Very little is known about the immunological responses of amphibians to pathogens that are causing global population declines. We used a custom microarray gene chip to characterize gene expression responses of axolotls (Ambystoma mexicanum) to an emerging viral pathogen, Ambystoma tigrinum virus (ATV).

Result: At 0, 24, 72, and 144 hours post-infection, spleen and lung samples were removed for estimation of host mRNA abundance and viral load.

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Background: Thyroid hormones (TH) induce gene expression programs that orchestrate amphibian metamorphosis. In contrast to anurans, many salamanders do not undergo metamorphosis in nature. However, they can be induced to undergo metamorphosis via exposure to thyroxine (T4).

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In contrast to mammals, salamanders have a remarkable ability to regenerate their spinal cord and recover full movement and function after tail amputation. To identify genes that may be associated with this greater regenerative ability, we designed an oligonucleotide microarray and profiled early gene expression during natural spinal cord regeneration in Ambystoma mexicanum. We sampled tissue at five early time points after tail amputation and identified genes that registered significant changes in mRNA abundance during the first 7 days of regeneration.

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Ambystomatid salamanders offer several advantages for endocrine disruption research, including genomic and bioinformatics resources, an accessible laboratory model (Ambystoma mexicanum), and natural lineages that are broadly distributed among North American habitats. We used microarray analysis to measure the relative abundance of transcripts isolated from A. mexicanum epidermis (skin) after exogenous application of thyroid hormone (TH).

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Objective: We retrospectively examined the database of the Pennsylvania Trauma Systems Foundation to determine the risk of pulmonary embolism in adult patients sustaining isolated head trauma or multiple injuries, including head trauma, to answer two questions: What is the incidence of symptomatic pulmonary embolism during hospitalization in a trauma center in patients who have sustained a head injury? Are patients with head injuries more at risk for pulmonary embolism than trauma patients without head injuries?

Methods: We determined the total number of adult submissions per year to the Pennsylvania Trauma Outcomes Study from 1992 to 1996. Age, sex, Glasgow Coma Scale score, Abbreviated Injury Score for head injury, Injury Severity Score, intensive care unit days, hospital days, and the presence or absence of head injury, spinal injury, pelvic fractures, and/or femur fractures were recorded. Statistical techniques to evaluate their correlation with the incidence of pulmonary embolism included chi(2) testing, linear regression analysis, Kendall analysis, and logistic regression analysis.

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