The Experts below are selected from a list of 231 Experts worldwide ranked by ideXlab platform
Edmund D. Brodie - One of the best experts on this subject based on the ideXlab platform.
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The geographic mosaic in parallel: Matching patterns of Newt tetrodotoxin levels and snake resistance in multiple predator-prey pairs.
The Journal of animal ecology, 2020Co-Authors: Jessica S. Reimche, Amber N. Stokes, Edmund D. Brodie, Erica J. Ely, Haley A. Moniz, Vicki L. Thill, Joshua M. Hallas, Michael E. Pfrender, Chris R. FeldmanAbstract:The Geographic Mosaic Theory of Coevolution predicts that coevolutionary arms races will vary over time and space because of the diverse ecological settings and population histories of interacting species across the landscape. Thus, understanding coevolution may require investigating broad sets of populations sampled across the range of the interaction. In addition, comparing coevolutionary dynamics between similar systems may reveal the importance of specific factors that structure coevolution. Here, we examine geographic patterns of prey traits and predator traits in the relatively unstudied interaction between the Sierra garter snake (Thamnophis couchii) and sympatric prey, the Rough-Skinned Newt (Taricha granulosa), Sierra Newt (Ta. sierrae) and California Newt (Ta. torosa). This system parallels, in space and phenotypes, a classic example of coevolution between predatory common garter snakes (Th. sirtalis) and their toxic Newt prey exhibiting hotspots of Newt tetrodotoxin (TTX) levels and matching snake TTX resistance. We quantified prey and predator traits from hundreds of individuals across their distributions, and functional trait matching at sympatric sites. We show strong regional patterns of trait covariation across the shared ranges of Th. couchii and Newt prey. Traits differ significantly among localities, with lower Newt TTX levels and snake TTX resistance at the northern latitudes, and higher TTX levels and snake resistance at southern latitudes. Newts and snakes in northern populations show the highest degree of functional trait matching despite possessing the least extreme traits. Conversely, Newts and snakes in southern populations show the greatest mismatch despite possessing exaggerated traits, with some snakes so resistant to TTX they would be unaffected by any sympatric Newt. Nevertheless, individual variation was substantial, and appears to offer the opportunity for continued reciprocal selection in most populations. Overall, the three species of Newts appear to be engaged in a TTX-mediated arms race with Th. couchii. These patterns are congruent with those seen between Newts and Th. sirtalis, including the same latitudinal gradient in trait covariation, and the potential 'escape' from the arms race by snake predators. Such concordance in broad scale patterns across two distinct systems suggests common phenomena might structure geographic mosaics in similar ways.
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Interacting stressors and the potential for adaptation in a changing world: responses of populations and individuals.
Royal Society open science, 2017Co-Authors: Gareth R. Hopkins, Susannah S. French, Edmund D. BrodieAbstract:To accurately predict the impact of environmental change, it is necessary to assay effects of key interacting stressors on vulnerable organisms, and the potential resiliency of their populations. Yet, for the most part, these critical data are missing. We examined the effects of two common abiotic stressors predicted to interact with climate change, salinity and temperature, on the embryonic survival and development of a model freshwater vertebrate, the Rough-Skinned Newt (Taricha granulosa) from different populations. We found that salinity and temperature significantly interacted to affect Newt embryonic survival and development, with the negative effects of salinity most pronounced at temperature extremes. We also found significant variation among, and especially within, populations, with different females varying in the performance of their eggs at different salinity-temperature combinations, possibly providing the raw material for future natural selection. Our results highlight the complex nature of predicting responses to climate change in space and time, and provide critical data towards that aim.
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To stress or not to stress: Physiological responses to tetrodotoxin in resistant gartersnakes vary by sex
Comparative biochemistry and physiology. Part A Molecular & integrative physiology, 2017Co-Authors: Lorin A. Neuman-lee, Edmund D. Brodie, Tyler Hansen, Susannah S. FrenchAbstract:The activation of the hypothalamic pituitary adrenal (HPA) axis is one of the most important physiological processes in coping with any deviation in an organism's homeostasis. This activation and the secretion of glucocorticoids, such as corticosterone, allow organisms to cope with perturbations and return to optimal physiological functioning as quickly as possible. In this study, we examined the HPA axis activation in common gartersnakes (Thamnophis sirtalis) as a response to a natural toxin, tetrodotoxin (TTX). This neurotoxin is found in high levels in the Rough-Skinned Newt (Taricha granulosa), which is a prey item for these snakes. To consume this toxic prey, these snakes have evolved variable resistance. We hypothesized that the more resistant individuals would show a lower HPA axis response than less resistant individuals, as measured by corticosterone (CORT) and bactericidal ability, which is a functional downstream measurement of CORT's activity. We determined “resistance level” for tetrodotoxin from each individual snake by determining the dose which reduced race speed by 50%. Individuals were injected them with an increasing amount of tetrodotoxin (10, 25, and 50 MAMUs) to determine this value. Thirty minutes after every injection, we gathered blood samples from each snake. Our results show that, while there were no significant differences among individual CORT levels in a dose-dependent manner, female snakes did have a larger stress response when compared to both males and juveniles. Different life-histories could explain why females were able to mount a higher HPA axis response. However, TTX had no downstream effects on bactericidal ability, although juveniles had consistently lower values than adults. Our research shows a possible dichotomy between how each sex manages tetrodotoxin and gives way for a more comprehensive analysis of tetrodotoxin in an ecological context.
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Data from Interacting stressors and the potential for adaptation in a changing world: responses of populations and individuals
2017Co-Authors: Gareth R. Hopkins, Susannah S. French, Edmund D. BrodieAbstract:To accurately predict the impact of environmental change, it is necessary to assay effects of key interacting stressors on vulnerable organisms, and the potential resiliency of their populations. Yet, for the most part, these critical data are missing. We examined the effects of two common abiotic stressors predicted to interact with climate change, salinity and temperature, on the embryonic survival and development of a model freshwater vertebrate, the Rough-Skinned Newt (Taricha granulosa) from different populations. We found that salinity and temperature significantly interacted to affect Newt embryonic survival and development, with the negative effects of salinity most pronounced at temperature extremes. We also found significant variation among, and especially within, populations, with different females varying in the performance of their eggs at different salinity–temperature combinations, possibly providing the raw material for future natural selection. Our results highlight the complex nature of predicting responses to climate change in space and time, and provide critical data towards that aim
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toxicity and population structure of the rough skinned Newt taricha granulosa outside the range of an arms race with resistant predators
Ecology and Evolution, 2016Co-Authors: Michael T J Hague, Charles T. Hanifin, Amber N. Stokes, Lelena A Avila, Andrew W Snedden, Edmund D. BrodieAbstract:: Species interactions, and their fitness consequences, vary across the geographic range of a coevolutionary relationship. This spatial heterogeneity in reciprocal selection is predicted to generate a geographic mosaic of local adaptation, wherein coevolutionary traits are phenotypically variable from one location to the next. Under this framework, allopatric populations should lack variation in coevolutionary traits due to the absence of reciprocal selection. We examine phenotypic variation in tetrodotoxin (TTX) toxicity of the Rough-Skinned Newt (Taricha granulosa) in regions of allopatry with its TTX-resistant predator, the Common Garter Snake (Thamnophis sirtalis). In sympatry, geographic patterns of phenotypic exaggeration in toxicity and toxin-resistance are closely correlated in prey and predator, implying that reciprocal selection drives phenotypic variation in coevolutionary traits. Therefore, in allopatry with TTX-resistant predators, we expect to find uniformly low levels of Newt toxicity. We characterized TTX toxicity in northwestern North America, including the Alaskan panhandle where Ta. granulosa occur in allopatry with Th. sirtalis. First, we used microsatellite markers to estimate population genetic structure and determine if any phenotypic variation in toxicity might be explained by historical divergence. We found northern populations of Ta. granulosa generally lacked population structure in a pattern consistent with northern range expansion after the Pleistocene. Next, we chose a cluster of sites in Alaska, which uniformly lacked genetic divergence, to test for phenotypic divergence in toxicity. As predicted, overall levels of Newt toxicity were low; however, we also detected unexpected among- and within-population variation in toxicity. Most notably, a small number of individuals contained large doses of TTX that rival means of toxic populations in sympatry with Th. sirtalis. Phenotypic variation in toxicity, despite limited neutral genetic divergence, suggests that factors other than reciprocal selection with Th. sirtalis likely contribute to geographic patterns of toxicity in Ta. granulosa.
Frank L Moore - One of the best experts on this subject based on the ideXlab platform.
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identification and characterization of mesotocin and v1a like vasotocin receptors in a urodele amphibian taricha granulosa
General and Comparative Endocrinology, 2011Co-Authors: Brian T Searcy, Samuel C Bradford, Theresa M Filtz, Richmond R. Thompson, Frank L MooreAbstract:Abstract The cDNA sequences encoding the mesotocin receptor (MTR) and vasotocin 1a receptor (VTR-1a) were identified in a urodele amphibian, the Rough-Skinned Newt, Taricha granulosa . Saturation binding of [ 3 H]oxytocin (OT) to the Taricha MTR (tMTR) was best fit by a two-state model; a high affinity-low abundance site and a lower affinity-high abundance site. Competition-binding studies found the following rank-order affinities for the tMTR: mesotocin (MT) > OT ≈ vasotocin (VT) > vasopressin (VP) > isotocin (IT). Inositol phosphate (IP) accumulation studies demonstrated functional activity of both the tMTR and Taricha VTR-1a (tVTR-1a) in a heterologous cell culture system. The rank-order potencies for the tMTR were MT > OT > VT ≈ VP > IT. The combined binding and IP results indicate that VT may act as a partial agonist of the tMTR. Rank-order potencies for the tVTR-1a were VT > VP > MT ≈ OT > IT. For both receptors, stimulation of IP accumulation was blocked by d(CH 2 ) 5 [Tyr(Me) 2 ]AVP (Manning compound) and d(CH 2 ) 5 [Tyr(Me) 2 ,Thr 4 ,Tyr-NH 2 ]OVT (OTA). OTA was a more potent antagonist for the transiently expressed tMTR while Manning compound was relatively more potent at inhibiting IP accumulation in tVTR-1a expressing cells. In contradiction to earlier assumptions, the absolute IC 50 of Manning compound was lower for the tMTR (27 nM ± 13) than the tVTR-1a (586 nM ± 166) indicating its potential higher affinity for the tMTR, a finding with special relevance to interpretation of comparative studies investigating the behavioral and physiological actions of neurohypophysial peptides in non-mammalian species.
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identification of mesotocin and vasotocin nucleotide sequences in two species of urodele amphibian
General and Comparative Endocrinology, 2009Co-Authors: Brian T Searcy, Eliza A Walthers, Bethany L Heppner, Richmond R. Thompson, Frank L MooreAbstract:We amplified and identified, for the first time in urodele amphibians, cDNA sequences that encode preprovasotocin (preproVT) and prepromesotocin (preproMT) from two distinct urodelian species, Taricha granulosa (the Rough-Skinned Newt) and Plethodon shermanii (the spotted salamander). Each of these cDNA sequences encoded proteins that contained the characteristics of known neurohypophysial peptide precursors; each sequence consisting of (1) a signal peptide, (2) VT- or MT-like peptides, (3) neurophysin, and for the preproVTs, (4) copeptin. In T. granulosa, cDNA sequences encoded for the nine amino acids that define VT or MT. In P. shermani, cDNA sequences encoded for the VT peptide and a previously unidentified isoform of MT, ([Val4]-MT).
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Neuroanatomical distribution of cannabinoid receptor gene expression in the brain of the Rough-Skinned Newt, Taricha granulosa.
Brain behavior and evolution, 2006Co-Authors: David M. Hollis, Emma Coddington, Frank L MooreAbstract:Type I cannabinoid receptor (CB1) is a G-protein coupled receptor with a widespread distribution in the central nervous system in mammals. In a urodele amphibian, the Rough-Skinned Newt (Tari
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Delta and mu opioid receptors from the brain of a urodele amphibian, the Rough-Skinned Newt Taricha granulosa: cloning, heterologous expression, and pharmacological characterization.
General and comparative endocrinology, 2005Co-Authors: C. Samuel Bradford, Eliza A Walthers, David J. Stanley, Martha M. Baugh, Frank L MooreAbstract:Two full-length cDNAs, encoding delta (delta) and mu (mu) opioid receptors, were cloned from the brain of the Rough-Skinned Newt Taricha granulosa, complementing previous work from our laboratory describing the cloning of Newt brain kappa (kappa) and ORL1 opioid receptors. The Newt delta receptor shares 82% amino acid sequence identity with a frog delta receptor and lower (68-70%) identity with orthologous receptors cloned from mammals and zebrafish. The Newt mu receptor shares 79% sequence identity with a frog mu receptor, 72% identity with mammalian mu receptors, and 66-69% identity with mu receptors cloned from teleost fishes. Membranes isolated from COS-7 cells transiently expressing the Newt delta receptor possessed a single, high-affinity (Kd = 2.4 nM) binding site for the nonselective opioid antagonist [3H]naloxone. In competition binding assays, the Newt delta receptor displayed highest affinity for Met-enkephalin, relatively low affinity for Leu-enkephalin, beta-endorphin, and [D-penicillamine, D-penicillamine] enkephalin (DPDPE) (a delta-selective agonist in mammals), and very low affinity for mu-, kappa-, or ORL1-selective agonists. COS-7 cells expressing the Newt mu receptor also possessed a high-affinity (Kd = 0.44 nM) naloxone-binding site that showed highest affinity for beta-endorphin, moderate-to-low affinity for Met-enkephalin and Leu-enkephalin and DAMGO (a mu-selective agonist in mammals), and very low affinity for DPDPE and kappa- or ORL1-selective agonists. COS-7 cells expressing either receptor type (delta or mu) showed very high affinity (Kd = 0.1-0.3 nM) for the nonselective opioid antagonist diprenorphine. Taricha granulosa expresses the same four subtypes (delta, mu, kappa, and ORL1) of opioid receptors found in other vertebrate classes, but ligand selectivity appears less stringent in the Newt than has been documented in mammals.
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Cloning proenkephalin from the brain of a urodele amphibian (Taricha granulosa) using a DOR-specific primer in a 3′RACE reaction
General and comparative endocrinology, 2005Co-Authors: Eliza A Walthers, Frank L MooreAbstract:A large cDNA fragment that codes for proenkephalin (PENK) was cloned from the Rough-Skinned Newt, Taricha granulosa (GenBank Accession: AY817670). This 1299-bp PENK cDNA extends from the poly(A) sequence on the 3' end into the 5'-UTR (221bp) upstream of an open reading frame that codes for 264 amino acids and a stop codon. Within the precursor are five Met-enkephalin sequences and two C-terminally extended forms of Met-enkephalin (YGGFMRGV and YGGFMRY). The organization of the opioid core sequences within the Newt PENK closely resembles that reported for other vertebrates. In this urodele amphibian, as in anurans, PENK does not contain the penultimate Leu-enkephalin opioid sequence found in mammals, and instead has in this position Met-enkephalin. PENK cDNA was amplified from Newt brain in a RACE PCR targeting the 3' end of the Newt delta opioid receptor (DOR). It remains to be determined whether generating the cDNA for the Newt PENK while cloning its receptor was serendipitous or the result of a meaningful coincidence between the DOR and PENK sequences.
Susannah S. French - One of the best experts on this subject based on the ideXlab platform.
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Interacting stressors and the potential for adaptation in a changing world: responses of populations and individuals.
Royal Society open science, 2017Co-Authors: Gareth R. Hopkins, Susannah S. French, Edmund D. BrodieAbstract:To accurately predict the impact of environmental change, it is necessary to assay effects of key interacting stressors on vulnerable organisms, and the potential resiliency of their populations. Yet, for the most part, these critical data are missing. We examined the effects of two common abiotic stressors predicted to interact with climate change, salinity and temperature, on the embryonic survival and development of a model freshwater vertebrate, the Rough-Skinned Newt (Taricha granulosa) from different populations. We found that salinity and temperature significantly interacted to affect Newt embryonic survival and development, with the negative effects of salinity most pronounced at temperature extremes. We also found significant variation among, and especially within, populations, with different females varying in the performance of their eggs at different salinity-temperature combinations, possibly providing the raw material for future natural selection. Our results highlight the complex nature of predicting responses to climate change in space and time, and provide critical data towards that aim.
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To stress or not to stress: Physiological responses to tetrodotoxin in resistant gartersnakes vary by sex
Comparative biochemistry and physiology. Part A Molecular & integrative physiology, 2017Co-Authors: Lorin A. Neuman-lee, Edmund D. Brodie, Tyler Hansen, Susannah S. FrenchAbstract:The activation of the hypothalamic pituitary adrenal (HPA) axis is one of the most important physiological processes in coping with any deviation in an organism's homeostasis. This activation and the secretion of glucocorticoids, such as corticosterone, allow organisms to cope with perturbations and return to optimal physiological functioning as quickly as possible. In this study, we examined the HPA axis activation in common gartersnakes (Thamnophis sirtalis) as a response to a natural toxin, tetrodotoxin (TTX). This neurotoxin is found in high levels in the Rough-Skinned Newt (Taricha granulosa), which is a prey item for these snakes. To consume this toxic prey, these snakes have evolved variable resistance. We hypothesized that the more resistant individuals would show a lower HPA axis response than less resistant individuals, as measured by corticosterone (CORT) and bactericidal ability, which is a functional downstream measurement of CORT's activity. We determined “resistance level” for tetrodotoxin from each individual snake by determining the dose which reduced race speed by 50%. Individuals were injected them with an increasing amount of tetrodotoxin (10, 25, and 50 MAMUs) to determine this value. Thirty minutes after every injection, we gathered blood samples from each snake. Our results show that, while there were no significant differences among individual CORT levels in a dose-dependent manner, female snakes did have a larger stress response when compared to both males and juveniles. Different life-histories could explain why females were able to mount a higher HPA axis response. However, TTX had no downstream effects on bactericidal ability, although juveniles had consistently lower values than adults. Our research shows a possible dichotomy between how each sex manages tetrodotoxin and gives way for a more comprehensive analysis of tetrodotoxin in an ecological context.
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Data from Interacting stressors and the potential for adaptation in a changing world: responses of populations and individuals
2017Co-Authors: Gareth R. Hopkins, Susannah S. French, Edmund D. BrodieAbstract:To accurately predict the impact of environmental change, it is necessary to assay effects of key interacting stressors on vulnerable organisms, and the potential resiliency of their populations. Yet, for the most part, these critical data are missing. We examined the effects of two common abiotic stressors predicted to interact with climate change, salinity and temperature, on the embryonic survival and development of a model freshwater vertebrate, the Rough-Skinned Newt (Taricha granulosa) from different populations. We found that salinity and temperature significantly interacted to affect Newt embryonic survival and development, with the negative effects of salinity most pronounced at temperature extremes. We also found significant variation among, and especially within, populations, with different females varying in the performance of their eggs at different salinity–temperature combinations, possibly providing the raw material for future natural selection. Our results highlight the complex nature of predicting responses to climate change in space and time, and provide critical data towards that aim
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Comparing the Natural and Anthropogenic Sodium Channel Blockers Tetrodotoxin and Indoxacarb in Garter Snakes
Journal of experimental zoology. Part A Ecological genetics and physiology, 2016Co-Authors: Lorin A. Neuman-lee, Edmund D. Brodie, Tyler Hansen, Susannah S. FrenchAbstract:Synthetic chemicals, such as pesticides, are used in a variety of ways in the agricultural industry. Anthropogenic chemicals pose a unique challenge to organisms because of the lack of evolutionary history between the chemical and the organism. However, research has shown that some organisms have a resistance to these synthetic chemicals due to their evolved resistance to a natural compound with a similar structure or mode of action. Indoxacarb (INDOX) is a relatively new pesticide with a similar mode of action to that of tetrodotoxin (TTX). Tetrodotoxin is a naturally occurring toxin that is used as an antipredator defense in the Rough-Skinned Newt (Taricha granulosa). Some populations of the common garter snake (Thamnophis sirtalis) have developed a resistance to tetrodotoxin. Here, we investigated the correlation between TTX and INDOX resistance in snakes. We hypothesized that INDOX would induce a much higher stress response than the naturally occurring TTX. We injected each snake with tetrodotoxin (1 mass-adjusted mouse unit). We did the same with mass-adjusted units of INDOX. We measured corticosterone, testosterone, and bactericidal ability. Our results show an acute stress response to INDOX, but not TTX through an elevate corticosterone and innate immune response, although there was no difference in testosterone concentration. These results suggest that, although INDOX may have a similar mechanism of action, garter snakes do not react in a similar manner as to TTX. This research gives a physiological perspective on the differences between naturally occurring compounds and synthetic compounds.
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Effects of temperature on embryonic and early larval growth and development in the Rough-Skinned Newt (Taricha granulosa).
Journal of thermal biology, 2015Co-Authors: Geoffrey D. Smith, Edmund D. Brodie, Gareth R. Hopkins, Shabnam Mohammadi, Heather M. Skinner, Tyler Hansen, Susannah S. FrenchAbstract:We investigated the effects of temperature on the growth and development of embryonic and early larval stages of a western North American amphibian, the Rough-Skinned Newt (Taricha granulosa). We assigned Newt eggs to different temperatures (7, 14, or 21°C); after hatching, we re-assigned the Newt larvae into the three different temperatures. Over the course of three to four weeks, we measured total length and developmental stage of the larvae. Our results indicated a strong positive relationship over time between temperature and both length and developmental stage. Importantly, individuals assigned to cooler embryonic temperatures did not achieve the larval sizes of individuals from the warmer embryonic treatments, regardless of larval temperature. Our investigation of growth and development at different temperatures demonstrates carry-over effects and provides a more comprehensive understanding of how organisms respond to temperature changes during early development.
Eliza A Walthers - One of the best experts on this subject based on the ideXlab platform.
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identification of mesotocin and vasotocin nucleotide sequences in two species of urodele amphibian
General and Comparative Endocrinology, 2009Co-Authors: Brian T Searcy, Eliza A Walthers, Bethany L Heppner, Richmond R. Thompson, Frank L MooreAbstract:We amplified and identified, for the first time in urodele amphibians, cDNA sequences that encode preprovasotocin (preproVT) and prepromesotocin (preproMT) from two distinct urodelian species, Taricha granulosa (the Rough-Skinned Newt) and Plethodon shermanii (the spotted salamander). Each of these cDNA sequences encoded proteins that contained the characteristics of known neurohypophysial peptide precursors; each sequence consisting of (1) a signal peptide, (2) VT- or MT-like peptides, (3) neurophysin, and for the preproVTs, (4) copeptin. In T. granulosa, cDNA sequences encoded for the nine amino acids that define VT or MT. In P. shermani, cDNA sequences encoded for the VT peptide and a previously unidentified isoform of MT, ([Val4]-MT).
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Delta and mu opioid receptors from the brain of a urodele amphibian, the Rough-Skinned Newt Taricha granulosa: cloning, heterologous expression, and pharmacological characterization.
General and comparative endocrinology, 2005Co-Authors: C. Samuel Bradford, Eliza A Walthers, David J. Stanley, Martha M. Baugh, Frank L MooreAbstract:Two full-length cDNAs, encoding delta (delta) and mu (mu) opioid receptors, were cloned from the brain of the Rough-Skinned Newt Taricha granulosa, complementing previous work from our laboratory describing the cloning of Newt brain kappa (kappa) and ORL1 opioid receptors. The Newt delta receptor shares 82% amino acid sequence identity with a frog delta receptor and lower (68-70%) identity with orthologous receptors cloned from mammals and zebrafish. The Newt mu receptor shares 79% sequence identity with a frog mu receptor, 72% identity with mammalian mu receptors, and 66-69% identity with mu receptors cloned from teleost fishes. Membranes isolated from COS-7 cells transiently expressing the Newt delta receptor possessed a single, high-affinity (Kd = 2.4 nM) binding site for the nonselective opioid antagonist [3H]naloxone. In competition binding assays, the Newt delta receptor displayed highest affinity for Met-enkephalin, relatively low affinity for Leu-enkephalin, beta-endorphin, and [D-penicillamine, D-penicillamine] enkephalin (DPDPE) (a delta-selective agonist in mammals), and very low affinity for mu-, kappa-, or ORL1-selective agonists. COS-7 cells expressing the Newt mu receptor also possessed a high-affinity (Kd = 0.44 nM) naloxone-binding site that showed highest affinity for beta-endorphin, moderate-to-low affinity for Met-enkephalin and Leu-enkephalin and DAMGO (a mu-selective agonist in mammals), and very low affinity for DPDPE and kappa- or ORL1-selective agonists. COS-7 cells expressing either receptor type (delta or mu) showed very high affinity (Kd = 0.1-0.3 nM) for the nonselective opioid antagonist diprenorphine. Taricha granulosa expresses the same four subtypes (delta, mu, kappa, and ORL1) of opioid receptors found in other vertebrate classes, but ligand selectivity appears less stringent in the Newt than has been documented in mammals.
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Cloning proenkephalin from the brain of a urodele amphibian (Taricha granulosa) using a DOR-specific primer in a 3′RACE reaction
General and comparative endocrinology, 2005Co-Authors: Eliza A Walthers, Frank L MooreAbstract:A large cDNA fragment that codes for proenkephalin (PENK) was cloned from the Rough-Skinned Newt, Taricha granulosa (GenBank Accession: AY817670). This 1299-bp PENK cDNA extends from the poly(A) sequence on the 3' end into the 5'-UTR (221bp) upstream of an open reading frame that codes for 264 amino acids and a stop codon. Within the precursor are five Met-enkephalin sequences and two C-terminally extended forms of Met-enkephalin (YGGFMRGV and YGGFMRY). The organization of the opioid core sequences within the Newt PENK closely resembles that reported for other vertebrates. In this urodele amphibian, as in anurans, PENK does not contain the penultimate Leu-enkephalin opioid sequence found in mammals, and instead has in this position Met-enkephalin. PENK cDNA was amplified from Newt brain in a RACE PCR targeting the 3' end of the Newt delta opioid receptor (DOR). It remains to be determined whether generating the cDNA for the Newt PENK while cloning its receptor was serendipitous or the result of a meaningful coincidence between the DOR and PENK sequences.
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Cloning, pharmacological characterization and tissue distribution of an ORL1 opioid receptor from an amphibian, the Rough-Skinned Newt Taricha granulosa.
Journal of molecular endocrinology, 2005Co-Authors: Eliza A Walthers, C. Samuel Bradford, Frank L MooreAbstract:We have cloned and characterized an opioid receptor-like (ORL1; also referred to as NOP) receptor from a urodele amphibian, the Rough-Skinned Newt Taricha granulosa The cDNA clone encodes a protein of 368 amino acids that contains the seven hydrophobic domains characteristic of G-protein-coupled receptors, and has the highest sequence identity to the frog (Rana pipiens) nociceptin-like and human ORL1 opioid receptors (79·6 and 68·4%, respectively). Saturation binding assays on membranes from COS-7 cells transiently expressing the Newt ORL1 (nORL) receptor revealed a single, high-affinity (estimated Kd, 0·1974 nM) binding site for the ORL1-specific agonist [3H]orphanin FQ analog ([3H]oFQ). In competition binding assays, the [3H]oFQ-binding site, like the mammalian ORL1 receptor, had no affinity for the non-selective opioid receptor antagonist naloxone, the -selective agonists U69593 and U50488, or the µ- and -selective opioid receptor agonists DAMGO and DPDPE, respectively. However, the nORL receptor displayed higher affinities for the -selective agonists dynorphin A (1–13), dynorphin B, and dynorphin A (1–8) (Ki values, 2·8, 151·8, and 183·0 nM, respectively) than its mammalian homologue. The tissue distribution of the nORL receptor, as determined by reverse transcriptase PCR, was also found to differ from reports on the mammalian ORL1 receptor, with mRNA detected in brain, spinal cord, and lung, but not detected in a number of other peripheral tissues reported to express the receptor in mammals. This is the first report describing the expression and characterization of an amphibian ORL1 receptor, and contributes to our understanding of the evolution of the opioid system.
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Cloning, heterologous expression and pharmacological characterization of a kappa opioid receptor from the brain of the Rough-Skinned Newt, Taricha granulosa
Journal of molecular endocrinology, 2005Co-Authors: C. Samuel Bradford, Brian T Searcy, Eliza A Walthers, Frank L MooreAbstract:A full-length cDNA that encodes a kappa (kappa) opioid receptor has been isolated from the brain of a urodele amphibian, the Rough-Skinned Newt Taricha granulosa. The deduced protein contains 385 amino acids and possesses features commonly attributed to G protein-coupled receptors, such as seven putative transmembrane domains. The Newt kappa receptor has 75% sequence identity to kappa opioid receptors cloned from mammals, and 66% sequence identity to the kappa opioid receptor reported for the zebrafish, with the greatest divergence in the extracellular N-terminus, the second and third extracellular loops and the intracellular C-terminus. Membranes isolated from COS-7 cells expressing the Newt kappa receptor possessed a single, high-affinity (Kd = 1.5 nM) binding site for the kappa-selective agonist U69593. In competition binding assays, the expressed Newt kappa receptor displayed high affinity for the kappa-selective agonists GR89696, dynorphin A(1-13), U69593, U50488 and BRL52537, as well as the kappa-selective antagonist nor-binaltorphimine and the non-selective antagonist naloxone. Rank order potencies and affinity constants were similar in competition binding studies that used either whole brain homogenates or membranes isolated from COS-7 cells expressing the Newt kappa receptor. The expressed receptor displayed essentially no affinity for the delta-selective agonist DPDPE ([d-penicillamine, d-penicillamine]enkephalin), but showed moderate affinity for the mu-selective agonist DAMGO ([d-Ala-MePhe, Gly-ol]enkephalin) and moderately high affinity for nociceptin (orphanin FQ), the endogenous ligand for the opioid receptor-like (ORL)1 receptor. These findings support the conclusions that a gene for the kappa opioid receptor is expressed in amphibians and that the pharmacology of the Newt kappa receptor closely matches mammalian kappa opioid receptors. However, the functional dichotomy between the classic opioid receptors (kappa, delta, mu) and ORL1 appears less strict in amphibians than in mammals.
Gareth R. Hopkins - One of the best experts on this subject based on the ideXlab platform.
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Interacting stressors and the potential for adaptation in a changing world: responses of populations and individuals.
Royal Society open science, 2017Co-Authors: Gareth R. Hopkins, Susannah S. French, Edmund D. BrodieAbstract:To accurately predict the impact of environmental change, it is necessary to assay effects of key interacting stressors on vulnerable organisms, and the potential resiliency of their populations. Yet, for the most part, these critical data are missing. We examined the effects of two common abiotic stressors predicted to interact with climate change, salinity and temperature, on the embryonic survival and development of a model freshwater vertebrate, the Rough-Skinned Newt (Taricha granulosa) from different populations. We found that salinity and temperature significantly interacted to affect Newt embryonic survival and development, with the negative effects of salinity most pronounced at temperature extremes. We also found significant variation among, and especially within, populations, with different females varying in the performance of their eggs at different salinity-temperature combinations, possibly providing the raw material for future natural selection. Our results highlight the complex nature of predicting responses to climate change in space and time, and provide critical data towards that aim.
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Data from Interacting stressors and the potential for adaptation in a changing world: responses of populations and individuals
2017Co-Authors: Gareth R. Hopkins, Susannah S. French, Edmund D. BrodieAbstract:To accurately predict the impact of environmental change, it is necessary to assay effects of key interacting stressors on vulnerable organisms, and the potential resiliency of their populations. Yet, for the most part, these critical data are missing. We examined the effects of two common abiotic stressors predicted to interact with climate change, salinity and temperature, on the embryonic survival and development of a model freshwater vertebrate, the Rough-Skinned Newt (Taricha granulosa) from different populations. We found that salinity and temperature significantly interacted to affect Newt embryonic survival and development, with the negative effects of salinity most pronounced at temperature extremes. We also found significant variation among, and especially within, populations, with different females varying in the performance of their eggs at different salinity–temperature combinations, possibly providing the raw material for future natural selection. Our results highlight the complex nature of predicting responses to climate change in space and time, and provide critical data towards that aim
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Effects of temperature on embryonic and early larval growth and development in the Rough-Skinned Newt (Taricha granulosa).
Journal of thermal biology, 2015Co-Authors: Geoffrey D. Smith, Edmund D. Brodie, Gareth R. Hopkins, Shabnam Mohammadi, Heather M. Skinner, Tyler Hansen, Susannah S. FrenchAbstract:We investigated the effects of temperature on the growth and development of embryonic and early larval stages of a western North American amphibian, the Rough-Skinned Newt (Taricha granulosa). We assigned Newt eggs to different temperatures (7, 14, or 21°C); after hatching, we re-assigned the Newt larvae into the three different temperatures. Over the course of three to four weeks, we measured total length and developmental stage of the larvae. Our results indicated a strong positive relationship over time between temperature and both length and developmental stage. Importantly, individuals assigned to cooler embryonic temperatures did not achieve the larval sizes of individuals from the warmer embryonic treatments, regardless of larval temperature. Our investigation of growth and development at different temperatures demonstrates carry-over effects and provides a more comprehensive understanding of how organisms respond to temperature changes during early development.
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The role of corticosterone and toxicity in the antipredator behavior of the Rough-Skinned Newt (Taricha granulosa).
General and comparative endocrinology, 2014Co-Authors: Lorin A. Neuman-lee, Amber N. Stokes, Edmund D. Brodie, Gareth R. Hopkins, Sydney Greenfield, Susannah S. FrenchAbstract:Abstract A variety of mechanisms are responsible for enabling an organism to escape a predatory attack, including behavioral changes, alterations in hormone levels, and production and/or secretion of toxins. However, these mechanisms are rarely studied in conjunction with each other. The Rough-Skinned Newt ( Taricha granulosa ) is an ideal organism to examine the relationships between these mechanisms because its behavioral displays and toxin secretion during a predator attack are well documented and readily characterized. While we found no direct relationship between antipredator behavior and endogenous levels of corticosterone (CORT), antipredator behavior was inhibited when exogenous CORT and adrenocorticotropic hormone (ACTH) were administered, resulting in high circulating concentrations of CORT, indicating that CORT may play a role in mediating the behavior. There was no correlation between the animal’s toxicity and either CORT or behavior. The results of this study provide evidence that CORT plays an important, yet complex, role in the antipredator response of these amphibians.
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Developmental and Evolutionary History Affect Survival in Stressful Environments
PloS one, 2014Co-Authors: Gareth R. Hopkins, Edmund D. Brodie, Susannah S. FrenchAbstract:The world is increasingly impacted by a variety of stressors that have the potential to differentially influence life history stages of organisms. Organisms have evolved to cope with some stressors, while with others they have little capacity. It is thus important to understand the effects of both developmental and evolutionary history on survival in stressful environments. We present evidence of the effects of both developmental and evolutionary history on survival of a freshwater vertebrate, the Rough-Skinned Newt (Taricha granulosa) in an osmotically stressful environment. We compared the survival of larvae in either NaCl or MgCl2 that were exposed to salinity either as larvae only or as embryos as well. Embryonic exposure to salinity led to greater mortality of Newt larvae than larval exposure alone, and this reduced survival probability was strongly linked to the carry-over effect of stunted embryonic growth in salts. Larval survival was also dependent on the type of salt (NaCl or MgCl2) the larvae were exposed to, and was lowest in MgCl2, a widely-used chemical deicer that, unlike NaCl, amphibian larvae do not have an evolutionary history of regulating at high levels. Both developmental and evolutionary history are critical factors in determining survival in this stressful environment, a pattern that may have widespread implications for the survival of animals increasingly impacted by substances with which they have little evolutionary history.
