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Jon P. Costanzo - One of the best experts on this subject based on the ideXlab platform.
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hepatocyte responses to in vitro freezing and β adrenergic stimulation insights into the extreme freeze tolerance of subarctic Rana sylvatica
Journal of Experimental Zoology, 2015Co-Authors: Clara Do M F Amaral, Jon P. CostanzoAbstract:The wood frog, Rana sylvatica LeConte 1825, is a freeze-tolerant amphibian widely distributed in North America. Subarctic populations of this species can survive experimental freezing to temperatures below � 16°C, whereas temperate populations tolerate freezing only at temper- atures above � 6°C. We investigated whether hepatocytes isolated from frogs indigenous to Interior Alaska (subarctic) or southern Ohio (temperate) had distinct characteristics that could contributetothisvariationinfreezetolerancecapacity.Followinginvitrofreezing,celldamage,as assessed from lactate dehydrogenase leakage, was similar between samples from Alaskan and Ohioan frogs. Preincubation of cells in media containing glucose or urea, the two primary cryoprotectants used by R. sylvatica, markedly reduced freezing damage to hepatocytes; however, results suggested that cells of the northern phenotype were comparatively more amenable to cryoprotection by urea. Stimulation of isolated hepatocytes with b-adrenergic agonists, which simulates the freezing-induced cryoprotectant mobilization response, gave rates of glucose production from endogenous glycogen reserves that were similar between the populations. Our findings suggest that extreme freeze tolerance in subarctic R. sylvatica does not require an enhancedabilityofthelivertoresistfreezingstressorrapidlymobilizecryoprotectant.J.Exp.Zool. 323A:89-96, 2015. © 2015 Wiley Periodicals, Inc. How to cite this article: do Amaral MCF, Lee Jr. RE, Costanzo JP. 2015. Hepatocyte responses to in vitro freezing and b-adrenergic stimulation: insights into the extreme freeze tolerance of subarctic Rana sylvatica. J. Exp. Zool. 323A:89-96. J. Exp. Zool. 323A:89-96, 2015
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effect of physiological stress on expression of glucose transporter 2 in liver of the wood frog Rana sylvatica
Journal of Experimental Zoology, 2014Co-Authors: Andrew J Rosendale, Jon P. CostanzoAbstract:Glucose transporters (GLUTs) have been implicated in the survival of various physiological stresses in mammals; however, little is known about the role of these proteins in stress tolerance in lower vertebrates. The wood frog (Rana sylvatica), which survives multiple winter-related stresses by copiously mobilizing hepatic glycogen stores, is an interesting subject for the study of glucose transport in amphibians. We examined the effects of several physiological stresses on GLUT2 protein and mRNA levels in the liver of R. sylvatica. Using immunoblotting techniques to measure relative GLUT2 abundance, we found that GLUT2 numbers increased in response to organismal freezing, hypoxia exposure, and glucose loading; whereas, experimental dehydration and urea loadingdidnotaffectGLUT2abundance.GLUT2mRNAlevels,assessedusingquantitativereal-time polymerase chain reaction, changed in accordance with protein abundance for most stresses, indicating that transcriptional regulation of GLUT2 occurs in response to stress. Overall, hepatic GLUT2 seems to be important in stress survival in R. sylvatica and is regulated to meet the physiological need to accumulate glucose. J. Exp. Zool. 321A:566-576, 2014. © 2014 Wiley Periodicals, Inc. Howtocitethisarticle: RosendaleAJ,LeeRE,CostanzoJP.2014.Effectofphysiological stresson expression of glucose transporter 2 in liver of the wood frog, Rana sylvatica. J. Exp. Zool. 321A:566-576.
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seasonality of freeze tolerance in a subarctic population of the wood frog Rana sylvatica
International Journal of Zoology, 2014Co-Authors: Jon P. Costanzo, Clara Do M F Amaral, Andrew J RosendaleAbstract:We compared physiological characteristics and responses to experimental freezing and thawing in winter and spring samples of the wood frog, Rana sylvatica, indigenous to Interior Alaska, USA. Whereas winter frogs can survive freezing at temperatures at least as low as −16°C, the lower limit of tolerance for spring frogs was between −2.5°C and −5°C. Spring frogs had comparatively low levels of the urea in blood plasma, liver, heart, brain, and skeletal muscle, as well as a smaller hepatic reserve of glycogen, which is converted to glucose after freezing begins. Consequently, following freezing (−2.5°C, 48 h) tissue concentrations of these cryoprotective osmolytes were 44–88% lower than those measured in winter frogs. Spring frogs formed much more ice and incurred extensive cryohemolysis and lactate accrual, indicating that they had suffered marked cell damage and hypoxic stress during freezing. Multiple, interactive stresses, in addition to diminished cryoprotectant levels, contribute to the reduced capacity for freeze tolerance in posthibernal frogs.
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seasonal variation and response to osmotic challenge in urea transporter expression in the dehydration and freeze tolerant wood frog Rana sylvatica
Journal of Experimental Zoology, 2012Co-Authors: Andrew J Rosendale, Jon P. CostanzoAbstract:Urea accumulation is a universal response to osmotic challenge in anuran amphibians, and facilitative urea transporters (UTs) seem to play an important role in this process by acting in the osmoregulatory organs to mediate urea retention. Although UTs have been implicated in urea reabsorptioninanurans,littleisknownaboutthephysiologicalregulationofUTproteinabundance. Weexamined seasonal variationin andeffects of osmotic challenge on UT protein and mRNA levels in kidney and urinary bladder of the wood frog (Rana sylvatica), a terrestrial species that tolerates both dehydration and tissue freezing. Using immunoblotting techniques to measure relative UT abundance,wefoundthatUTnumbersvariedseasonally,withalowabundanceprevailinginthefall and winter, and higher levels occurring in the spring. Experimental dehydration of frogs increased UT protein abundance in the urinary bladder, whereas experimental urea loading decreased the abundance of UTs in kidney and bladder. Experimental freezing, whether or not followed by thawing, had no effect on UT numbers. UT mRNA levels, assessed using quantitative real-time polymerase chain reaction, did not change seasonally nor in response to any of our experimental treatments. These findings suggest that regulation of UTs depends on the nature and severity of the osmotic stress and apparently occurs posttranscriptionally in response to multiple physiological factors. Additionally, UTs seem to be regulated to meet the physiological need to accumulate urea, with UT numbers increasing to facilitate urea reabsorption and decreasing to prevent retention of excess urea. J. Exp. Zool. 317A:401-409, 2012. © 2012 Wiley Periodicals, Inc. How to cite this article: Rosendale AJ, Costanzo JP, Lee RE. 2012. Seasonal variation and response to osmotic challenge in urea transporter expression in the dehydration- and freeze- tolerant wood frog, Rana sylvatica. J. Exp. Zool. 317A:401-409. J. Exp. Zool. 317A:401-409, 2012
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seasonal variation in the hepatoproteome of the dehydration and freeze tolerant wood frog Rana sylvatica
International Journal of Molecular Sciences, 2011Co-Authors: Andor J Kiss, Timothy J Muir, Jon P. CostanzoAbstract:Winter’s advent invokes physiological adjustments that permit temperate ectotherms to cope with stresses such as food shortage, water deprivation, hypoxia, and hypothermia. We used liquid chromatography (LC) in combination with tandem mass spectrometry (MS/MS) quantitative isobaric (iTRAQ™) peptide mapping to assess variation in the abundance of hepatic proteins in summer- and winter-acclimatized wood frogs (Rana sylvatica), a northerly-distributed species that tolerates extreme dehydration and tissue freezing during hibernation. Thirty-three unique proteins exhibited strong seasonal lability. Livers of winter frogs had relatively high levels of proteins involved in cytoprotection, including heat-shock proteins and an antioxidant, and a reduced abundance of proteins involved in cell proliferation, protein synthesis, and mitochondrial function. They also exhibited altered levels of certain metabolic enzymes that participate in the biochemical reorganization associated with aphagia and reliance on energy reserves, as well as the freezing mobilization and post-thaw recovery of glucose, an important cryoprotective solute in freezing adaptation.
K B Storey - One of the best experts on this subject based on the ideXlab platform.
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histone methylation in the freeze tolerant wood frog Rana sylvatica
Journal of Comparative Physiology B-biochemical Systemic and Environmental Physiology, 2018Co-Authors: Liam J Hawkins, K B StoreyAbstract:Freeze-tolerant animals survive sub-zero temperatures and long-term starvation associated with the winter by lowering their metabolic rate using a variety of transcriptional, translational, and post-translational regulatory methods. Histone methylation is one mechanism that is known to regulate gene expression at the transcriptional level. Here, we measured relative protein levels of seven histone methyltransferases (SMYD2, SETD7, ASH2L, RBBP5, SUV39H1, EHMT2, and SET8), four methylated histone H3 residues (H3K4me1, H3K9me3, H3K27me1, and H3K36me2), the methyltransferase activity on H3K4, and methylation of p53 (p53K370me2 and p53K372me1) in the skeletal muscle and liver of the freeze-tolerant wood frog (Rana sylvatica) during the freeze–thaw cycle. Overall, the results reveal a tissue-specific expression of histone methyltransferases and the methylation sites on histone H3 during freezing and thaw. In liver, H3K4me1 significantly decreased during freezing, H3K9me3 remained constant across conditions, H3K27me1 increased only during thaw, and H3K36me2 increased during freezing and then decreased during thaw (p < 0.05, n = 4). In skeletal muscle, H3K4me1 and H3K27me1 both decreased during freezing, whereas H3K9me3 and H3K36me2 were maintained across freezing and thaw (p < 0.05, n = 4). Methylation of p53 was also tissue-specific, where no changes were seen in liver tissue; however, p53 in skeletal muscle was differentially methylated. Overall, these results provide an evidence for the potential role methylation of histones and non-histone proteins play in freezing survival and entrance into a hypometabolic state.
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akt signaling and freezing survival in the wood frog Rana sylvatica
Biochimica et Biophysica Acta, 2013Co-Authors: Jing Zhang, K B StoreyAbstract:Abstract Background The wood frog ( Rana sylvatica ) exhibits well-developed natural freeze tolerance supported by multiple mechanisms of biochemical adaptation. The present study investigated the role and regulation of the Akt signaling pathway in wood frog tissues (with a focus on liver) responding to freezing stress. Methods Immunoblotting was used to assess total and phospho-Akt levels, total and phospho-PDK1, PTEN protein level, as well as total and phospho-FOXO1 levels. RT-PCR was used to investigate transcript levels of PTEN and microRNAs. Results Akt was inhibited in skeletal muscle, kidney and heart after 24 h freezing exposure with a reversal after thawing. The responses of the main kinase (PDK-1) and phosphatase (PTEN) that regulate Akt were consistent with freeze activation of Akt in liver; freezing exposure activated PDK-1 via enhanced Ser-241 phosphorylation whereas PTEN protein levels were reduced. Levels of three microRNAs (miR-26a, miR-126 and miR-217) that regulate pten expression were elevated in liver during freezing. One well-known role of Akt is in anti-apoptosis, mediated in part by Akt phosphorylation of Ser-256 on FOXO1. Freezing triggered an increase in liver phospho-FOXO1 Ser-256 content, suggesting that an important action of Akt may be apoptosis inhibition. Conclusions Akt activation in wood frog is stress and tissue specific, with multi-facet regulations (posttranslational and posttranscriptional) involved in supporting this specific signal transduction response. General significance This study implicates the Akt pathway in the metabolic reorganization of cellular metabolism in support of freezing survival.
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cell cycle regulation in the freeze tolerant wood frog Rana sylvatica
Cell Cycle, 2012Co-Authors: Jing Zhang, K B StoreyAbstract:The wood frog (Rana sylvatica) is one of only a few vertebrate species that can survive extensive freezing of its body fluids during the winter. The mechanisms of natural freeze tolerance include metabolic rate depression to conserve energy and the implementation of cryoprotective strategies, especially the synthesis of huge amounts of glucose as a cryoprotectant. Liver is the main source of glucose production/export (and other cryoprotective actions) and plays a central role in freezing survival of the whole animal. Freezing is a multi-component stress that includes anoxia/ischemia due to the cessation of blood flow and dehydration of cells caused by ice accumulation in extracellular spaces. To help endure these stresses, cells need to suppress and reprioritize ATP-expensive cell functions. One of these is cell growth and proliferation, and we hypothesized that cell cycle arrest would be key to freezing survival. The present study examines the responses by key cell cycle components to freezing, anoxia an...
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glycation of wood frog Rana sylvatica hemoglobin and blood proteins in vivo and in vitro studies
Cryobiology, 2009Co-Authors: Justin A Macdonald, Thorsten P Degenhardt, John W Baynes, K B StoreyAbstract:The effects of in vivo freezing and glucose cryoprotectant on protein glycation were investigated in the wood frog, Rana sylvatica. Our studies revealed no difference in the fructoselysine content of blood plasma sampled from control, 27 h frozen and 18 h thawed wood frogs. Glycated hemoglobin (GHb) decreased slightly with 48 h freezing exposure and was below control levels after 7 d recovery, while glycated serum albumin was unchanged by 48 h freezing but did increase after 7 d of recovery. In vitro exposure of blood lysates to glucose revealed that the GHb production in wood frogs was similar to that of the rat but was lower than in leopard frogs. We conclude that wood frog hemoglobin was glycated in vitro; however, GHb production was not apparent during freezing and recovery when in vivo glucose is highly elevated. It is possible that wood frog blood proteins have different in vivo susceptibilities to glycation.
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identification and characterization of a novel freezing inducible gene li16 in the wood frog Rana sylvatica
The FASEB Journal, 2002Co-Authors: Dayre J Mcnally, Shaobo Wu, Christopher M Sturgeon, K B StoreyAbstract:SPECIFIC AIMSIdentification and analysis of the biochemical adaptations that support winter freezing survival by selected amphibians and reptiles not only provides a greater understanding of this unusual phenomenon, but suggests molecular strategies that could be applicable in medical cryopreservation. The present study documents the freeze up-regulation of a novel gene, li16, in liver of the wood frog (Rana sylvatica), monitors changes in gene/protein expression under freezing, anoxia and dehydration stresses, demonstrates probable li16 regulation by a cGMP-dependent mechanism, and suggests a role for the protein in ischemia resistance during freezing.PRINCIPAL FINDINGS1. Freezing induces increased transcription of li16 mRNADifferential screening of a wood frog liver cDNA library coupled with 5′RACE was used to obtain 446 base pairs of a 0.5 kb freeze-induced transcript from liver of frozen frogs. The sequence, named li16, contained a full open reading frame (348 base pairs, 115 amino acids), a start cod...
Jinzhong Fu - One of the best experts on this subject based on the ideXlab platform.
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the effect of habitat fragmentation on finescale population structure of wood frogs Rana sylvatica
Conservation Genetics, 2009Co-Authors: Kathrine M A Crosby, Lawrence E Licht, Jinzhong FuAbstract:We examined the impact of recent anthropogenic habitat fragmentation on the genetic structure of wood frog (Rana sylvatica) breeding sites in Wellington County of Ontario, Canada. In addition to geographic distance (average pairwise distance ~22 km, greatest distance ~50.22 km), four landscape features hypothesized to contribute to genetic differentiation between breeding sites were considered: road density, a major highway (highway 401), canopy cover, and watershed discontinuity. Analysis of data from 396 samples across nine breeding sites using eight microsatellite DNA loci, revealed a small degree of significant genetic structure between breeding sites. The presence of highway 401 and road density were correlated with small but statistically significant structure observed between several groups of sites. One outlier breeding site outside of Wellington County located within the city of Toronto, had significantly lower allelic richness and much larger population differentiation with the Wellington sites. Our data suggest that recent fragmentation has had an effect on wood frog population structure and also demonstrate the importance of dispersal for this species in maintaining levels of genetic diversity.
Andrew J Rosendale - One of the best experts on this subject based on the ideXlab platform.
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Characterization and physiological regulation of glucose transporter 2 in the liver of the wood frog, Rana sylvatica: Implications for freeze tolerance
2020Co-Authors: Andrew J RosendaleAbstract:CHARACTERIZATION AND PHYSIOLOGICAL REGULATION OF GLUCOSE TRANSPORTER 2 IN THE LIVER OF THE WOOD FROG, Rana sylvatica: IMPLICATIONS FOR FREEZE TOLERANCE by Andrew J. Rosendale Winter presents organisms inhabiting temperate regions with various stresses, including low temperature. To contend with subzero temperatures, a small group of ectotherms tolerate freezing, in part through the use of cryoprotective solutes. In the wood frog, Rana sylvatica, glucose serves an important role in freezing survival; however, the mechanisms underlying the transport and distribution of cryoprotectants such as glucose are not fully understood. This dissertation describes several studies that examined a glucose transport protein (GLUT2) and its importance in the freeze tolerance of R. sylvatica. First, I identified and functionally characterized a GLUT2 homolog from R. sylvatica to understand its role in glucose homeostasis. The newly identified GLUT2 was structurally and phylogenetically similar to other known GLUT2s. Measurements of transport kinetics in Xenopus oocytes determined that GLUT2 from R. sylvatica is functionally similar to previously characterized GLUT2s. This protein was found in various tissues but was most abundant in liver. Finally, transport kinetics were similar among two populations of R. sylvatica, and R. pipiens; however, GLUT2 abundance was greatest in the northern R. sylvatica. R. sylvatica relies on glucose to survive multiple winter-related stresses, and the second study examined regulation of GLUT2 in response to these stresses. GLUT2 expression increased in response to organismal freezing, hypoxia exposure, and glucose loading; whereas, experimental dehydration and urea loading had no effect. These changes were the result of transcriptional regulation, resulting in synthesis of new protein. Results of this study suggest that hepatic GLUT2 is regulated to meet the physiological need to accumulate glucose. Subarctic populations of R. sylvatica survive freezing to lower temperatures than conspecifics from temperate regions. In the last study, I sought to determine if GLUT2 contributes to the profound freeze tolerance of northern frogs. We examined GLUT2 expression in R. sylvatica from Interior Alaska and Ohio and found that GLUT2 abundance increased in preparation for winter in both populations, but that GLUT2 abundance was greater in Alaskan frogs. In Alaskan, but not Ohioan, frogs, GLUT2 protein increased in response to experimental freezing. These results suggest that GLUT2 is important in the extreme freeze tolerance of northern wood frogs. CHARACTERIZATION AND PHYSIOLOGICAL REGULATION OF GLUCOSE TRANSPORTER 2 IN THE LIVER OF THE WOOD FROG, Rana sylvatica: IMPLICATIONS FOR FREEZE TOLERANCE
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effect of physiological stress on expression of glucose transporter 2 in liver of the wood frog Rana sylvatica
Journal of Experimental Zoology, 2014Co-Authors: Andrew J Rosendale, Jon P. CostanzoAbstract:Glucose transporters (GLUTs) have been implicated in the survival of various physiological stresses in mammals; however, little is known about the role of these proteins in stress tolerance in lower vertebrates. The wood frog (Rana sylvatica), which survives multiple winter-related stresses by copiously mobilizing hepatic glycogen stores, is an interesting subject for the study of glucose transport in amphibians. We examined the effects of several physiological stresses on GLUT2 protein and mRNA levels in the liver of R. sylvatica. Using immunoblotting techniques to measure relative GLUT2 abundance, we found that GLUT2 numbers increased in response to organismal freezing, hypoxia exposure, and glucose loading; whereas, experimental dehydration and urea loadingdidnotaffectGLUT2abundance.GLUT2mRNAlevels,assessedusingquantitativereal-time polymerase chain reaction, changed in accordance with protein abundance for most stresses, indicating that transcriptional regulation of GLUT2 occurs in response to stress. Overall, hepatic GLUT2 seems to be important in stress survival in R. sylvatica and is regulated to meet the physiological need to accumulate glucose. J. Exp. Zool. 321A:566-576, 2014. © 2014 Wiley Periodicals, Inc. Howtocitethisarticle: RosendaleAJ,LeeRE,CostanzoJP.2014.Effectofphysiological stresson expression of glucose transporter 2 in liver of the wood frog, Rana sylvatica. J. Exp. Zool. 321A:566-576.
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seasonality of freeze tolerance in a subarctic population of the wood frog Rana sylvatica
International Journal of Zoology, 2014Co-Authors: Jon P. Costanzo, Clara Do M F Amaral, Andrew J RosendaleAbstract:We compared physiological characteristics and responses to experimental freezing and thawing in winter and spring samples of the wood frog, Rana sylvatica, indigenous to Interior Alaska, USA. Whereas winter frogs can survive freezing at temperatures at least as low as −16°C, the lower limit of tolerance for spring frogs was between −2.5°C and −5°C. Spring frogs had comparatively low levels of the urea in blood plasma, liver, heart, brain, and skeletal muscle, as well as a smaller hepatic reserve of glycogen, which is converted to glucose after freezing begins. Consequently, following freezing (−2.5°C, 48 h) tissue concentrations of these cryoprotective osmolytes were 44–88% lower than those measured in winter frogs. Spring frogs formed much more ice and incurred extensive cryohemolysis and lactate accrual, indicating that they had suffered marked cell damage and hypoxic stress during freezing. Multiple, interactive stresses, in addition to diminished cryoprotectant levels, contribute to the reduced capacity for freeze tolerance in posthibernal frogs.
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seasonal variation and response to osmotic challenge in urea transporter expression in the dehydration and freeze tolerant wood frog Rana sylvatica
Journal of Experimental Zoology, 2012Co-Authors: Andrew J Rosendale, Jon P. CostanzoAbstract:Urea accumulation is a universal response to osmotic challenge in anuran amphibians, and facilitative urea transporters (UTs) seem to play an important role in this process by acting in the osmoregulatory organs to mediate urea retention. Although UTs have been implicated in urea reabsorptioninanurans,littleisknownaboutthephysiologicalregulationofUTproteinabundance. Weexamined seasonal variationin andeffects of osmotic challenge on UT protein and mRNA levels in kidney and urinary bladder of the wood frog (Rana sylvatica), a terrestrial species that tolerates both dehydration and tissue freezing. Using immunoblotting techniques to measure relative UT abundance,wefoundthatUTnumbersvariedseasonally,withalowabundanceprevailinginthefall and winter, and higher levels occurring in the spring. Experimental dehydration of frogs increased UT protein abundance in the urinary bladder, whereas experimental urea loading decreased the abundance of UTs in kidney and bladder. Experimental freezing, whether or not followed by thawing, had no effect on UT numbers. UT mRNA levels, assessed using quantitative real-time polymerase chain reaction, did not change seasonally nor in response to any of our experimental treatments. These findings suggest that regulation of UTs depends on the nature and severity of the osmotic stress and apparently occurs posttranscriptionally in response to multiple physiological factors. Additionally, UTs seem to be regulated to meet the physiological need to accumulate urea, with UT numbers increasing to facilitate urea reabsorption and decreasing to prevent retention of excess urea. J. Exp. Zool. 317A:401-409, 2012. © 2012 Wiley Periodicals, Inc. How to cite this article: Rosendale AJ, Costanzo JP, Lee RE. 2012. Seasonal variation and response to osmotic challenge in urea transporter expression in the dehydration- and freeze- tolerant wood frog, Rana sylvatica. J. Exp. Zool. 317A:401-409. J. Exp. Zool. 317A:401-409, 2012
Geoffrey R. Smith - One of the best experts on this subject based on the ideXlab platform.
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Interactive effects of food availability and temperature on wood frog (Rana sylvatica) tadpoles
Herpetological Journal, 2020Co-Authors: Brett Castano, Geoffrey R. Smith, Shawn Miely, Jessica E RettigAbstract:Temperature and food availability can affect the growth and survivorship ofectothermic vertebrates. We examined how the interaction of temperature and food availability influenced the growth and survival of wood frog (Rana sylvatica) tadpoles. Tadpoles experiencing 17 °C survived better than tadpoles experiencing 25 °C. The difference in survivorship between temperature treatments tended to be highest at the lowest food level. Tadpoles in the high food treatment were significantly heavier than tadpoles in other treatments. Tadpoles in the 25 °C treatment were larger than tadpoles in the 17 °C treatment. Tadpoles were substantially heavier in the high food, warm temperature treatment combination than in other treatments. Our results suggest the effects of temperature change on amphibian populations could be mediated by food availability.
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Effects of potential predator and competitor cues and sibship on wood frog (Rana sylvatica) embryos
Amphibia-reptilia, 2020Co-Authors: Geoffrey R. Smith, Jessica E Rettig, Christopher J. Dibble, Evan Zuzik, Jamie KauffmanAbstract:Chemical cues emitted from predators or competitors are often important for animals living in aquatic ecosystems as they allow potential prey to assess predation risk and make appropriate risk-sensitive responses. In our experiment, we examined if wood frog (Rana sylvatica) embryos exposed to potential predator and competitor cues would alter their time to hatching, size at hatching, or survivorship. Eggs from four different sibships were subjected to a variety of cues including dragonfly larvae (potential tadpole predator), mosquitofish (Gambusia affinis; a non-native potential egg and tadpole predator), and overwintered tadpoles of Rana sp. (potential competitors). We found no significant effects of any of the cues. However, we did find significant variation in mean time to hatching and mean hatchling size among sibships. Our results suggest that wood frog embryos may have limited ability to respond to some cues at the embryonic stage, at least for the concentrations and conditions used in this experiment. Our results do indicate genetic or parental effects can affect embryonic wood frog development rate and hatchling size.
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effects of salinity on survivorship of wood frog Rana sylvatica tadpoles
Journal of Freshwater Ecology, 2009Co-Authors: Margaret Langhans, Geoffrey R. Smith, Bridget Peterson, Annie Walker, Jessica E RettigAbstract:ABSTRACT We examined the survivorship of wood frog (Rana sylvatica) tadpoles when exposed continuously to various concentrations of sodium chloride, a common component of road salt. A high environmental concentration of NaC1 (5.6 g L−1) resulted in decreased survivorship within a short period of time compared to controls; lower concentrations of NaC1 also decreased survivorship, but the effect took longer to appear. These results indicate that environmental salinization, as results from road salt run-off, will have negative consequences for the wood frog.
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Actue Toxic Effects of Round-Up Herbicide on Wood Frog Tadpoles (Rana sylvatica)
Journal of Freshwater Ecology, 2007Co-Authors: Brett A. Comstock, Spencer L. Sprinkle, Geoffrey R. SmithAbstract:ABSTRACT We examine the toxicity of a commercial formulation of Round-Up to wood frog (Rana sylvatica) tadpoles. All tadpoles exposed to nominal concentrations ≥ 0.00098% glyphosate died within 24 h. However, tadpoles exposed to concentrations ≤ 0.00049% showed high survivorship. Our results suggest that any direct application of this formulation of Round-Up to aquatic ecosystems could have an impact on amphibian larvae, especially in shallow water
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Within-Pond Oviposition Site Selection in Two Spring-Breeding Amphibians (Ambystoma maculatum and Rana sylvatica)
Journal of Freshwater Ecology, 2005Co-Authors: Christopher K. Dougherty, David A. Vaala, Geoffrey R. SmithAbstract:ABSTRACT We examined within-pond oviposition site selection by two spring-breeding amphibians, the spotted salamander (Ambystoma maculatum) and the wood frog (Rana sylvatica), in two small ponds in central Ohio. Both species deposited their eggs in a non-random pattern within the ponds, ovipositing closer to shore and in shallower water than would be expected by chance. Rana sylvatica eggs were laid in warmer sites that had lower dissolved oxygen levels than random sites. Ambystoma maculatum egg masses tended to be fairly isolated from other A. maculatum egg masses, whereas R. sylvatica egg masses were highly aggregated.
