| hormonal effects on glycogen metabolism in isolated hepatocytes of a freeze-tolerant frog. | to determine whether specific hormonal responses were involved in the production of cryoprotectant (glucose) by liver of the freeze tolerant wood frog, rana sylvatica, metabolically active hepatocytes were isolated in reasonable yields (mean 20.1 +/- 1.30% sem, n = 29) by in situ liver perfusion with collagenase. freshly isolated cells from autumn-collected frogs contained large amounts of glycogen (650 mumol glucosyl units/g packed cells) and produced glucose from this endogenous reserve at a r ... | 1992 | 1624097 |
| freeze-thaw injury in erythrocytes of the freeze-tolerant wood frog, rana sylvatica. | erythrocytes from the freeze-tolerant wood frog (rana sylvatica) were subjected to in vitro tests of freeze tolerance, cryoprotection, and osmotic fragility. the responses of cells from frogs acclimated to 4 or 15 degrees c were similar. erythrocytes that were frozen in saline hemolyzed at -4 degrees c or lower. the addition of high concentrations (150 and 1,500 mm) of glucose or glycerol, cryoprotectants produced naturally by freeze-tolerant frogs, significantly reduced cell injury at -8 degree ... | 1991 | 1750558 |
| life in a frozen state: adaptive strategies for natural freeze tolerance in amphibians and reptiles. | winter survival for various species of amphibians and reptiles that hibernate on land depends on freeze tolerance, the ability to survive for long periods of time with up to 65% of total body water as extracellular ice. freeze tolerance has been described for four species of frogs, one salamander, and hatchlings of the painted turtle. a very limited tolerance also occurs in garter snakes. studies of freeze tolerance in vertebrates have primarily focused on the wood frog rana sylvatica and have a ... | 1990 | 2180324 |
| electrophoretic analysis of liver glycogen phosphorylase activation in the freeze-tolerant wood frog. | as an adaptation for overwinter survival, the wood frog, rana sylvatica is able to tolerate the freezing of extracellular body fluids. tolerance is made possible by the production of very high amounts of glucose in liver which is then sent to other organs where it acts as a cryoprotectant. cryoprotectant synthesis is under the control of glycogen phosphorylase which in turn is activated in response to ice formation. to determine the mechanism of phosphorylase activation, a quantitative analysis ... | 1988 | 2841983 |
| the effects of thiosemicarbazide on development in the wood frog, rana sylvatica. i. concentration effects. | the effects of exposure of rana sylvatica tadpoles to varying concentrations (10-75 mg/liter for 4 days) of thiosemicarbazide (tsc) was studied. exposure to concentrations of 25 mg/liter or more caused a curvature of digits, abnormal limb articulations, difficulty in swimming, and death. for all of these parameters, effects were dose dependent. tadpoles exposed to 10 mg/liter metamorphosed significantly slower than controls while those exposed to 50 mg/liter metamorphosed significantly faster th ... | 1986 | 3792267 |
| limb regeneration and nerve fiber number in rana sylvatica and xenopus laevis. | | 1966 | 5962946 |
| isolation of ice-nucleating active bacteria from the freeze-tolerant frog, rana sylvatica. | ice-nucleating active (ina) bacteria were isolated from the gut of field-collected freeze-tolerant wood frogs (rana sylvatica) collected in winter. thirteen strains of pseudomonas fluorescens, four strains of pseudomonas putida, and two strains of enterobacter agglomerans had ice-nucleating activity. each of the ina pseudomonad strains was psychrophilic. p. putida strains were differentiated from p. fluorescens strains by gelatinase, lecithinase, and lipase production. the maximum nucleation tem ... | 1995 | 7656570 |
| characterization of gamma-glutamyltranspeptidase in the liver of the frog: 1. comparison to the rat liver enzyme. | the characteristics of the enzyme gamma-glutamyltranspeptidase were determined in frog liver and compared to those of the rat. in rana pipiens, tissue distribution studies indicated the order of activity to be: kidney >>> liver >> nerve > egg > lung > heart > skeletal muscle in homogenates. in the rana pipiens relative to the fischer 344 rat, the activity of the liver enzyme was somewhat greater (1.8-fold) and the kidney enzyme substantially less (25-fold). frog liver gamma-glutamyltranspeptidas ... | 1994 | 7909503 |
| freezing-induced genes in wood frog (rana sylvatica): fibrinogen upregulation by freezing and dehydration. | differential screening of a cdna library produced from liver of the freeze-tolerant wood frog, rana sylvatica, was used to search for freezing-induced genes. five freezing-responsive cdna clones representing different genes were isolated when approximately 80,000 plaques of a cdna library, prepared from liver of frozen frogs (24 h at -2.5 degrees c), were screened with 32p-labeled total cdna probes from control (5 degrees c) versus freezing-exposed frogs. two clones, pbffr45 and pbffr04, are rep ... | 1997 | 9176340 |
| differential regulation of the mitochondrial adp/atp translocase gene in wood frogs under freezing stress. | the gene aat coding for adp/atp translocase (aat) was cloned from liver of the freeze-tolerant wood frog, rana sylvatica, via differential screening of a cdna library from liver of frozen frogs and using probes from control versus frozen frogs. sequence analysis showed that clone pbffr07 bearing the aat cdna contained a 1318-bp insert with one full-length open reading frame. the deduced amino acid sequence included 317 residues, with 81-86% identities to mammalian aat. a 1750-nt transcript from ... | 1997 | 9256066 |
| coexistence of alpha1 and beta adrenergic receptors in the liver of the frog rana esculenta, the toad bufo bufo, the lizard podarcis sicula campestris, and the turtle pseudemys picta elegans. | in mammals and birds the characteristics of alpha1 adrenergic receptors and their biological role in liver metabolism have been clearly described, although the predominance of receptor subtypes varies with species. in contrast, the actual presence of hepatic alpha1 adrenergic receptors in fish, amphibians, and reptiles has been questioned. only recently has their existence been demonstrated in some fish species and also in the wood frog rana sylvatica. the present study assessed the presence of ... | 1997 | 9268616 |
| cryopreservation of spermatozoa from freeze-tolerant and -intolerant anurans. | spermatozoa of the freeze-tolerant wood frog (rana sylvatica) were used to develop a general protocol for the frozen storage of amphibian spermatozoa. tolerance of spermatozoa to cryoprotective agents and freezing in suspension (-80 degrees c) was determined from rates of sperm lysis and dual-fluorochrome vital dye assays. we tested the efficacy of four cryoprotectants (me2so, methanol, glycerol, and ethylene glycol), two supplements (fetal bovine serum or glutathione), and combinations of these ... | 1998 | 9769166 |
| freeze tolerance in the wood frog rana sylvatica is associated with unusual structural features in insulin but not in glucagon. | the wood frog rana sylvatica utilises glucose, derived from hepatic glycogen, as a cryoprotectant in order to survive freezing during winter hibernation, and glycogenolysis is initiated by hormonal and/or neural stimuli. the primary structure of insulin was determined from r. sylvatica and from two species of freeze-intolerant ranid frogs r. catesbeiana (american bullfrog) and r. ridibunda (european green frog). all three insulins contain a dipeptide (lys-pro) extension to the n-terminus of the ... | 1998 | 9801458 |
| liver freezing response of the freeze-tolerant wood frog, rana sylvatica, in the presence and absence of glucose. ii. mathematical modeling. | the "two-step" low-temperature microscopy (equilibrium and dynamic) freezing methods and a differential scanning calorimetry (dsc) technique were used to assess the equilibrium and dynamic cell volumes in rana sylvatica liver tissue during freezing, in part i of this study. in this study, the experimentally determined dynamic water transport data are curve fit to a model of water transport using a standard krogh cylinder geometry (model 1) to predict the biophysical parameters of water transport ... | 1999 | 10413575 |
| induction of synthesis of an antimicrobial peptide in the skin of the freeze-tolerant frog, rana sylvatica, in response to environmental stimuli. | an extract of skin taken from specimens of the freeze-tolerant wood frog, rana sylvatica, that were collected from cold (<7 degrees c) ponds and maintained at 5 degrees c lacked detectable antimicrobial activity. in contrast, an extract of skin taken from specimens maintained at 30 degrees c for 3 weeks under laboratory conditions contained a high concentration (approximately 4 nmol/g) of a single antimicrobial peptide of the brevinin-1 family (flpvvaglaakvlpsiicavtkkc). the peptide inhibited gr ... | 2000 | 11042268 |
| forest mediated light regime linked to amphibian distribution and performance. | the vegetation in and around the basins of ephemeral wetlands can greatly affect light environments for aquatic species such as amphibians. we used hemispherical photographs to quantify the light environment in terms of the global site factor (gsf), the proportion of available solar radiation that actually strikes the wetland. we compared gsf to the distribution and performance of two amphibian species (pseudacris crucifer and rana sylvatica) within 17 ephemeral wetlands in northeastern connecti ... | 2003 | 12647143 |
| synergistic impacts of malathion and predatory stress on six species of north american tadpoles. | the decline of many amphibian populations is associated with pesticides, but for most pesticides we know little about their toxicity to amphibians. malathion is a classic example; it is sprayed over aquatic habitats to control mosquitoes that carry malaria and the west nile virus, yet we know little about its effect on amphibians. i examined the survival of six species of tadpoles (wood frogs, rana sylvatica; leopard frogs, r. pipiens; green frogs, r. clamitans; bullfrogs, r. catesbeiana; americ ... | 2004 | 15095908 |
| five amphibian mortality events associated with ranavirus infection in south central ontario, canada. | using field, molecular and histological methods, an epizootic, systemic disease causing death within wood frog rana sylvatica tadpoles and leopard frog rana pipiens metamorphs at 3 different locations within southern ontario, canada, has been investigated. our results demonstrated that the probable cause of this disease was a ranavirus. affected amphibians were found to exhibit necrosis within the hematopoietic cells. liver tissue samples were found positive for the virus by pcr amplification of ... | 2005 | 16385802 |
| ranavirus in wood frogs (rana sylvatica): potential sources of transmission within and between ponds. | members of the genus ranavirus (family iridoviridae) can cause catastrophic mortality of pond-breeding amphibians and are associated with an emerging infectious disease that may be contributing to amphibian declines. we conducted three experiments to examine factors that may affect transmission both within and between local breeding populations of the wood frog (rana sylvatica). in a laboratory study, when exposed to moribund tadpoles collected during a local ranaviral die-off, uninfected tadpol ... | 2006 | 16870853 |
| a new species of rhabdias from lungs of the wood frog, rana sylvatica, in north america: the last sibling of rhabdias ranae? | rhabdias bakeri n. sp. is described from specimens found in lungs of the wood frog, rana sylvatica, from north dakota. the new species has previously been mistakenly identified as rhabdias ranae walton, 1929, a common parasite of the leopard frog, rana pipiens. the new species differs from r. ranae and rhabdias joaquinensis ingles, 1935 by the shape and size of pseudolabia, shape and size of buccal capsule, and wider esophageal bulb. molecular analysis based on the partial sequences of nuclear 1 ... | 2006 | 16884011 |
| rates of development in male and female wood frogs and patterns of parasitism by lung nematodes. | researchers are becoming interested in testing whether investment in growth and/or development trades off against investment in parasite defence. we tested this idea by examining relations between development of wood frogs (rana sylvatica) and susceptibility to lung nematodes (rhabdias ranae). male and female frogs reared in outdoor mesocosms were the same length and mass at metamorphosis. however, males metamorphosed sooner than females. lung nematodes were no more likely to penetrate male vers ... | 2008 | 17991306 |
| frog virus 3-like infections in aquatic amphibian communities. | frog virus 3 (fv3) and fv3-like viruses, are members of the genus ranavirus (family iridoviridae), and they have been associated with infectious diseases that may be contributing to amphibian population declines. we examined the mode of transmission of an fv3-like virus, and potential hosts and reservoirs of the virus in a local amphibian community. using the polymerase chain reaction to detect infected animals, we found an fv3-like virus in south-central ontario, canada, amphibian communities, ... | 2008 | 18263826 |
| nematode lungworms of two species of anuran amphibians: evidence for co-adaptation. | genetic studies have indicated that some parasite species formerly thought to be generalists are complexes of morphologically similar species, each appearing to specialize on different host species. studies on such species are needed to obtain ecological and parasitological data to address whether there are fitness costs in parasitizing atypical host species. we examined whether lungworms from two anuran host species, lithobates sylvaticus and lithobates pipiens, differed in measures of infectio ... | 2008 | 18572173 |
| cold acclimation-induced up-regulation of the ribosomal protein l7 gene in the freeze tolerant wood frog, rana sylvatica. | natural freezing survival by the wood frog, rana sylvatica, involves multiple organ-specific changes in gene expression. the present study used differential display pcr to find cold-responsive genes in wood frog skin. a cdna was retrieved from skin that was in higher amounts in cold- versus warm-acclimated frogs. the cdna was used to probe a wood frog liver cdna library and retrieve a long sequence that, after the further application of 5'race, was shown to encode the full sequence of the riboso ... | 2008 | 18706984 |
| road proximity increases risk of skeletal abnormalities in wood frogs from national wildlife refuges in alaska. | skeletal and eye abnormalities in amphibians are not well understood, and they appear to be increasing while global populations decline. here, we present the first study of amphibian abnormalities in alaska. | 2008 | 18709167 |
| demographic consequences of terrestrial habitat loss for pool-breeding amphibians: predicting extinction risks associated with inadequate size of buffer zones. | much of the biodiversity associated with isolated wetlands requires aquatic and terrestrial habitat to maintain viable populations. current federal wetland regulations in the united states do not protect isolated wetlands or extend protection to surrounding terrestrial habitat. consequently, some land managers, city planners, and policy makers at the state and local levels are making an effort to protect these wetland and neighboring upland habitats. balancing human land-use and habitat conserva ... | 2008 | 18717698 |
| phosphoglycerate kinase 1 expression responds to freezing, anoxia, and dehydration stresses in the freeze tolerant wood frog, rana sylvatica. | natural freezing survival by wood frogs (rana sylvatica) involves multiple organ-specific changes in gene expression. screening of a cdna library made from brain of frozen frogs revealed freeze-responsive up-regulation of the glycolytic enzyme, phosphoglycerate kinase 1 (pgk1). northern blots showed an approximately two-fold increase in pgk1 transcripts in brain of frozen frogs whereas pgk1 protein levels rose by three- to five-fold within 4-8 hr of freezing. freezing also elevated pgk1 transcri ... | 2009 | 18785212 |
| terrestrial habitat selection and strong density-dependent mortality in recently metamorphosed amphibians. | to predict the effects of terrestrial habitat change on amphibian populations, we need to know how amphibians respond to habitat heterogeneity, and whether habitat choice remains consistent throughout the life-history cycle. we conducted four experiments to evaluate how the spatial distribution of juvenile wood frogs, rana sylvatica (including both overall abundance and localized density), was influenced by habitat choice and habitat structure, and how this relationship changed with spatial scal ... | 2008 | 18831177 |
| glycation of wood frog (rana sylvatica) hemoglobin and blood proteins: in vivo and in vitro studies. | 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 7d recovery, while glycated serum albumin was unchanged by 48 h freezing but did increase after 7d of recovery. in vi ... | 2009 | 19540217 |
| evidence for urea-induced hypometabolism in isolated organs of dormant ectotherms. | many organisms endure extended periods of dormancy by depressing their metabolism, which effectively prolongs the use of their endogenous energy stores. though the mechanisms of hypometabolism are varied and incompletely understood, recent work suggests that urea accumulation in autumn and early winter contributes to reduced metabolism of hibernating wood frogs (rana sylvatica). urea accumulation during dormancy is a widespread phenomenon, and it has long been presumed that numerous species from ... | 2010 | 19739087 |
| experimental transmission of hepatozoon clamatae (apicomplexa: adeleida) to the wood frog, rana sylvatica, and to the mosquito culex pipiens. | hepatozoon clamatae naturally infects the erythrocytes of green frogs (rana clamitans), bullfrogs (rana catesbeiana), and northern leopard frogs (rana pipiens) in northeastern north america and uses the mosquito culex territans as a definitive host. in this study, we show that the wood frog, rana sylvatica, supports merogonic development, but not gamogonic development, of this protozoan parasite, and that the mosquito culex pipiens serves as an experimental definitive host for sporogonic develop ... | 2010 | 19895159 |
| preliminary amphibian health survey in the delaware water gap national recreation area. | to detect aquatic animal diseases of national concern, 111 individual amphibians, including wood frogs rana sylvatica (28), spring peepers pseudacris crucifer (35), red-spotted newts notophthalmus viridescens (41), and gray tree frogs hyla versicolor (7), were sampled at seven different sites in the delaware water gap national recreation area (dgnra), pennsylvania, from june 14 to july 19, 2007. these samples were screened for batrachochytrium dendrobatidis and viral pathogens at the u.s. fish a ... | 2010 | 20848885 |
| isolation of tn1546-like elements in vancomycin-resistant enterococcus faecium isolated from wood frogs: an emerging risk for zoonotic bacterial infections to humans. | isolation and characterization of vancomycin-resistant enterococci (vre), mainly enterococcus faecium, from the faecal pellet of wood frogs (rana sylvatica). | 2010 | 20880145 |
| compromised metamorphosis and thyroid hormone changes in wood frogs (lithobates sylvaticus) raised on reclaimed wetlands on the athabasca oil sands. | the wet landscape approach to oil sands tailings reclamation in the athabasca oil sands region involves creating wetlands from fluid tailings in mined-out pits. we measured time to metamorphosis, thyroid hormone status, and detoxification enzyme (erod) induction in wood frog (lithobates sylvaticus) tadpoles raised on reclaimed oil sands wetlands of different ages [young (≤ 7 yr) vs. old (> 7 yr)] and compared data with tadpoles raised on reference (control) wetlands. metamorphosis was delayed or ... | 2010 | 21036440 |
| characterization of a xenopus tropicalis endogenous retrovirus with developmental and stress-dependent expression. | we report on the identification and characterization of xterv1, a full-length endogenous retrovirus (erv) within the genome of the western clawed frog (xenopus tropicalis). xterv1 contains all the basic genetic elements common to ervs, including the classical 5'-long terminal repeat (ltr)-gag-pol-env-3'-ltr architecture, as well as conserved functional motifs inherent to each retroviral protein. using phylogenetic analysis, we show that xterv1 is related to the epsilonretrovirus genus. the x. tr ... | 2010 | 21159866 |
| the combined influence of trematode parasites and predatory salamanders on wood frog (rana sylvatica) tadpoles. | predators can have important impacts on host-parasite dynamics. for many directly transmitted parasites, predators can reduce transmission by removing the most heavily infected individuals from the population. less is known about how predators might influence parasite dynamics in systems where the parasite relies on vectors or multiple host species to complete their life cycles. digenetic trematodes are parasitic flatworms with complex life cycles typically involving three host species. they are ... | 2011 | 21384178 |
| presence of ribeiroia ondatrae in the developing anuran limb disrupts retinoic acid levels. | the widespread reports of malformed frogs have sparked interest worldwide to try and determine the causes of such malformations. ribeiroia ondatrae is a digenetic trematode, which has been implicated as one such cause, as this parasite encysts within the developing tadpole hind limb bud and inguinal region causing dramatic limb malformations. currently, the mechanisms involved in parasite-induced limb deformities remain unclear. we sought to investigate whether the level of retinoic acid (ra), a ... | 2011 | 21614545 |
| differential host susceptibility toôçébatrachochytrium dendrobatidis, an emerging amphibian pathogen. | ôçé the amphibian fungal pathogenôçébatrachochytrium dendrobatidisôçé(bd) has received considerable attention due to its role in amphibian population declines worldwide. although many amphibian species appear to be affected by bd, there is little information on species-specific differences in susceptibility to this pathogen. we used a comparative experimental approach to examine bd susceptibility in 6 amphibian species from the united states. we exposed postmetamorphic animals to bd for 30 days ... | 2011 | 21732979 |
| varying responses of northeastern north american amphibians to the chytrid pathogen batrachochytrium dendrobatidis. | chytridiomycosis, caused by batrachochytrium dendrobatidis (bd), is widespread among amphibians in northeastern north america. it is unknown, however, whether bd has the potential to cause extensive amphibian mortalities in northeastern north america as have occurred elsewhere. in the laboratory, we exposed seven common northeastern north american amphibian species to bd to assess the likelihood of population-level effects from the disease. we exposed larval wood frogs (lithobates sylvaticus) an ... | 2011 | 22181933 |
| effect of cooling rate on the survival of frozen wood frogs, rana sylvatica. | wood frogs (rana sylvatica) were frozen to -2.5 degrees c under five distinct cooling regimes to investigate the effect of cooling rate on survival. frogs survived freezing when cooled at -0.16 degrees c.h-1 or -0.18 degrees c.h-1, but mortality resulted at higher rates (-0.30 degrees c.h-1, -1.03 degrees c.h-1, and -1.17 degrees c.h-1). surviving frogs in the latter groups required longer periods to recover, and transient injury to the neuromuscular system was evident. some of the frogs that di ... | 2007 | 1939737 |
| cryomicroscopic analysis of freezing in liver of the freeze-tolerant wood frog. | the technique of directional solidification coupled with low-temperature scanning electron microscopy was applied to analyze the freezing of liver slices from the freeze-tolerant frog rana sylvatica. micrographs of liver slices from 5 degrees c-acclimated frogs frozen on the directional stage to -7 degrees c showed continuous ice formed along an expanded vasculature with hepatocytes that were shrunken and virtually dehydrated. however, when frogs were given a survivable freezing exposure at -4 d ... | 2006 | 1636785 |
| the effects of thiosemicarbazide on development in the wood frog, rana sylvatica. ii. critical exposure length and age sensitivity. | wood frog (rana sylvatica) tadpoles were exposed to 50 mg thiosemicarbazide (tsc)/liter water for varying lengths of time and at different developmental stages. short exposure periods (3 and 6 hr) resulted in no visible deformities. exposure periods of 12 or more hr caused slight to severe abnormalities, with a direct relationship between length of exposure and degree of deformity. tadpoles exposed to tsc from posthatching days 24-30 were more seriously affected than were tadpoles exposed at an ... | 2012 | 3595487 |
| learning by embryos and the ghost of predation future. | most research on the effects of exposure to stressful stimuli during embryonic development has focused on post-embryonic behaviour that appears to be abnormal or maladaptive. here, we tested whether exposure to some stressful stimuli (predatory cues) can lead to post-embryonic behaviour that is adaptive. when eggs of ringed salamanders (ambystoma annulatum) were exposed to chemical cues from predators, post-hatching larvae showed reduced activity and greater shelter-seeking behaviour; larvae tha ... | 0 | 18682368 |
| pesticide tolerance in amphibians: induced tolerance in susceptible populations, constitutive tolerance in tolerant populations. | the role of plasticity in shaping adaptations is important to understanding the expression of traits within individuals and the evolution of populations. with increasing human impacts on the environment, one challenge is to consider how plasticity shapes responses to anthropogenic stressors such as contaminants. to our knowledge, only one study (using mosquitoes) has considered the possibility of induced insecticide tolerance. using populations of wood frogs (lithobates sylvaticus) located close ... | 2013 | 24187585 |
| regulation of the rana sylvatica brevinin-1sy antimicrobial peptide during development and in dorsal and ventral skin in response to freezing, anoxia and dehydration. | brevinin-1sy is the only described antimicrobial peptide (amp) of rana sylvatica. as amps are important innate immune molecules that inhibit microbes, this study examined brevinin-1sy regulation during development and in adult frogs in response to environmental stress. the brevinin-1sy nucleotide sequence was identified and used for protein modeling. brevinin-1sy was predicted to be an amphipathic, hydrophobic, alpha helical peptide that inserts into a lipid bilayer. brevinin-1sy transcripts wer ... | 2014 | 24436376 |
| disease dynamics of red-spotted newts and their anuran prey in a montane pond community. | long-term monitoring of amphibians is needed to clarify population-level effects of ranaviruses (rv) and the fungal pathogen batrachochytrium dendrobatidis (bd). we investigated disease dynamics of co-occurring amphibian species and potential demographic consequences of rv and bd infections at a montane site in the southern appalachians, georgia, usa. our 3-yr study was unique in combining disease surveillance with intensive population monitoring at a site where both pathogens are present. we de ... | 2016 | 26912042 |
| differences in sensitivity to the fungal pathogen batrachochytrium dendrobatidis among amphibian populations. | contributing to the worldwide biodiversity crisis are emerging infectious diseases, which can lead to extirpations and extinctions of hosts. for example, the infectious fungal pathogen batrachochytrium dendrobatidis (bd) is associated with worldwide amphibian population declines and extinctions. sensitivity to bd varies with species, season, and life stage. however, there is little information on whether sensitivity to bd differs among populations, which is essential for understanding bd-infecti ... | 2015 | 26219571 |
| amphibian pathogens at northern latitudes: presence of chytrid fungus and ranavirus in northeastern canada. | infections by the fungal pathogen batrachochytrium dendrobatidis (bd) and members of the genus ranavirus (rv) are increasingly reported as significant determinants of amphibian population die-offs. the complexity associated with their transmission and spatial distribution leads to an increase in demand for comprehensive reporting systems and global mapping of their distribution. here, we document the distribution of these 2 pathogens in a remote northern temperate lowland where environmental sen ... | 2015 | 25751857 |
| carotenoids and amphibians: effects on life history and susceptibility to the infectious pathogen, batrachochytrium dendrobatidis. | carotenoids are considered beneficial nutrients because they provide increased immune capacity. although carotenoid research has been conducted in many vertebrates, little research has been done in amphibians, a group that is experiencing global population declines from numerous causes, including disease. we raised two amphibian species through metamorphosis on three carotenoid diets to quantify the effects on life-history traits and post-metamorphic susceptibility to a fungal pathogen (batracho ... | 2015 | 27293690 |
| larval exposure to predator cues alters immune function and response to a fungal pathogen in post-metamorphic wood frogs. | for the past several decades, amphibian populations have been decreasing around the globe at an unprecedented rate. batrachochytrium dendrobatidis (bd), the fungal pathogen that causes chytridiomycosis in amphibians, is contributing to amphibian declines. natural and anthropogenic environmental factors are hypothesized to contribute to these declines by reducing the immunocompetence of amphibian hosts, making them more susceptible to infection. antimicrobial peptides (amps) produced in the granu ... | 2013 | 24147415 |
| first survey for the amphibian chytrid fungus batrachochytrium dendrobatidis in connecticut (usa) finds widespread prevalence. | the amphibian chytrid fungus batrachochytrium dendrobatidis (bd) is an emerging infectious fungal pathogen of amphibians and is linked to global population declines. until now, there has only been 1 survey for the fungus in the northeastern usa, which focused primarily on northern new england. we tested for bd in a large number of samples (916 individuals from 116 sites) collected throughout the state of connecticut, representing 18 native amphibian species. in addition, 239 preserved wood frog ... | 2013 | 23446966 |
| host invasion by batrachochytrium dendrobatidis: fungal and epidermal ultrastructure in model anurans. | the chytridiomycete fungus batrachochytrium dendrobatidis (bd) colonizes mouthparts of amphibian larvae and superficial epidermis of post-metamorphic amphibians, causing the disease chytridiomycosis. fungal growth within host cells has been documented by light and transmission electron microscopy; however, entry of the fungus into host cells has not. our objective was to document how bd enters host cells in the wood frog lithobates sylvaticus, a species at high mortality risk for chytridiomycosi ... | 2012 | 22968788 |
| transmission of batrachochytrium dendrobatidis to wood frogs (lithobates sylvaticus) via a bullfrog (l. catesbeianus) vector. | chytridiomycosis, an emerging infectious disease caused by the chytrid fungus batrachochytrium dendrobatidis, threatens anuran populations worldwide. effects of b. dendrobatidis on frog species are variable. some species typically develop nonlethal infections and may function as carriers; others typically develop lethal infections that can lead to population declines. nonlethal infections in the bullfrog (lithobates catesbeianus) are well-documented. in contrast, recently metamorphosed wood frog ... | 2012 | 22740523 |
| the benefits of coinfection: trematodes alter disease outcomes associated with virus infection. | 1.coinfections are increasingly recognized as important drivers of disease dynamics. consequently, greater emphasis has been placed on integrating principles from community ecology with disease ecology to understand within-host interactions among parasites. using larval amphibians and two amphibian parasites (ranaviruses and the trematode echinoparyphium sp.), we examined the influence of coinfection on disease outcomes. 2.our first objective was to examine how priority effects (the timing and s ... | 2017 | 28317105 |
| pathogenesis of frog virus 3 ( ranavirus, iridoviridae) infection in wood frogs ( rana sylvatica). | wood frogs ( rana sylvatica) are highly susceptible to infection with frog virus 3 (fv3, ranavirus, iridoviridae), a cause of mass mortality in wild populations. to elucidate the pathogenesis of fv3 infection in wood frogs, 40 wild-caught adults were acclimated to captivity, inoculated orally with a fatal dose of 10(4.43) pfu/frog, and euthanized at 0.25, 0.5, 1, 2, 4, 9, and 14 days postinfection (dpi). mild lesions occurred sporadically in the skin (petechiae) and bone marrow (necrosis) during ... | 2017 | 28060677 |
| reciprocal effects of pesticides and pathogens on amphibian hosts: the importance of exposure order and timing. | ecological communities are increasingly exposed to natural and anthropogenic stressors. while the effects of individual stressors have been broadly investigated, there is growing evidence that multiple stressors are frequently encountered underscoring the need to examine interactive effects. pesticides and infectious diseases are two common stressors that regularly occur together in nature. given the documented lethal and sublethal effects of each stressor on individuals, there is the potential ... | 2017 | 27939635 |
| hematologic reference intervals for rana sylvatica (lithobates sylvaticus) and effect of infection with frog virus 3 (ranavirus sp., iridoviridae). | although the wood frog, rana sylvatica, is used in research on infectious diseases of amphibians, hematologic ris or response to infection have not been established. | 2016 | 27564850 |
| water temperature affects susceptibility to ranavirus. | the occurrence of emerging infectious diseases in wildlife populations is increasing, and changes in environmental conditions have been hypothesized as a potential driver. for example, warmer ambient temperatures might favor pathogens by providing more ideal conditions for propagation or by stressing hosts. our objective was to determine if water temperature played a role in the pathogenicity of an emerging pathogen (ranavirus) that infects ectothermic vertebrate species. we exposed larvae of fo ... | 2016 | 27283058 |
| clinical signs, pathology and dose-dependent survival of adult wood frogs, rana sylvatica, inoculated orally with frog virus 3 ranavirus sp., iridoviridae. | amphibian populations suffer massive mortalities from infection with frog virus 3 fv3, genus ranavirus, family iridoviridae, a pathogen also involved in mortalities of fish and reptiles. experimental oral infection with fv3 in captive-raised adult wood frogs, rana sylvatica lithobates sylvaticus, was performed as the first step in establishing a native north american animal model of ranaviral disease to study pathogenesis and host response. oral dosing was successful ld50 was 10(2.93 2.423.44) p ... | 2015 | 25593158 |
| environmental dependency of amphibian-ranavirus genotypic interactions: evolutionary perspectives on infectious diseases. | the context-dependent investigations of host-pathogen genotypic interactions, where environmental factors are explicitly incorporated, allow the assessment of both coevolutionary history and contemporary ecological influences. such a functional explanatory framework is particularly valuable for describing mortality trends and identifying drivers of disease risk more accurately. using two common north american frog species (lithobates pipiens and lithobates sylvaticus) and three strains of frog v ... | 2014 | 25469155 |
| phylogenetic analysis of a frog virus 3-like ranavirus found at a site with recurrent mortality and morbidity events in southeastern ontario, canada: partial major capsid protein sequence alone is not sufficient for fine-scale differentiation. | ranaviruses are emerging pathogens of amphibians. we examined the phylogenetic relationship of ranaviruses from infected lithobates sylvaticus tadpoles 2001-2004 from oliver pond, ontario, canada. the isolates sequenced are primarily frog virus 3-like, but because of sequence convergence, finer-scale analysis based on the major capsid protein was uninformative. | 2013 | 23568931 |
| bottom-up and trait-mediated effects of resource quality on amphibian parasitism. | leaf litter subsidies are important resources for aquatic consumers like tadpoles and snails, causing bottom-up effects on wetland ecosystems. recent studies have shown that variation in litter nutritional quality can be as important as litter quantity in driving these bottom-up effects. resource subsidies likely also have indirect and trait-mediated effects on predation and parasitism, but these potential effects remain largely unexplored. we generated predictions for differential effects of li ... | 2017 | 28027571 |
| impact of forestry practices at a landscape scale on the dynamics of amphibian populations. | forest loss is a primary cause of worldwide amphibian decline. timber harvesting in the united states has caused dramatic changes in quality and extent of forest ecosystems, and intensive forest management still occurs. although numerous studies have documented substantial reductions in amphibian densities related to timber harvest, subsequent extinctions are rare. to better understand the population dynamics that have allowed so many amphibian species to persist in the face of widespread forest ... | 2015 | 26910954 |
| an examination of multiple factors affecting community structure in an aquatic amphibian community. | the potential effects of multiple factors structuring certain larval amphibian communities were studied using a pen experiment in a natural pond. potential factors (predation and competition from other species) were allowed to act in a stepwise fashion such that their relative importance could be evaluated. based on a previous study, it was hypothesized that predation by ambystoma salamander larvae on other larval amphibian species would be the most important factor. survival of ambystoma jeffer ... | 1990 | 28313252 |
| temperature-mediated changes in rates of predator forgetting in woodfrog tadpoles. | hundreds of studies have investigated the sources and nature of information that prey gather about their predators and the ways in which prey use this information to mediate their risk of predation. however, relatively little theoretical or empirical work has considered the question of how long information should be maintained and used by prey animals in making behavioural decisions. here, we tested whether the size of the memory window associated with predator recognition could be affected by a ... | 2012 | 23251438 |
| learning about non-predators and safe places: the forgotten elements of risk assessment. | a fundamental prerequisite for prey to avoid being captured is the ability to distinguish dangerous stimuli such as predators and risky habitats from non-dangerous stimuli such as non-predators and safe locations. most research to date has focused on mechanisms allowing prey to learn to recognize risky stimuli. the paradox of learned predator recognition is that its remarkable efficiency leaves room for potentially costly mistakes if prey inadvertently learn to recognize non-predatory species as ... | 2011 | 21203793 |
| amphibian survival, growth and development in response to mineral nitrogen exposure and predator cues in the field: an experimental approach. | mineral nitrogen (n) has been suggested as a potential factor causing declines in amphibian populations, especially in agricultural landscapes; however, there is a question as to whether it remains in the water column long enough to be toxic. we explored the hypothesis that mineral n can cause both lethal and sublethal toxic effects in amphibian embryos and larvae in a manipulative field experiment. we sampled 12 ponds, fertilizing half with ammonium nitrate fertilizer early in the spring, and m ... | 2007 | 17351792 |
| ontogenic delays in effects of nitrite exposure on tiger salamanders (ambystoma tigrinum tigrinum) and wood frogs (rana sylvatica). | under certain conditions, nitrite can be present in freshwater systems in quantities that are toxic to the fauna. i exposed wood frog (rana sylvatica) and eastern tiger salamander (ambystoma tigrinum tigrinum) embryos and young tadpoles and larvae to elevated concentrations of nitrite in chronic toxicity tests: 0, 0.3, 0.6, 1.2, 2.1, 4.6, and 6.1 mg/l no2-n, exposing individuals as both embryos and larvae. nitrite caused significant declines in wood frog hatching success (3.4 mg/l no2-n, wood fr ... | 2005 | 16117132 |
| new effects of roundup on amphibians: predators reduce herbicide mortality; herbicides induce antipredator morphology. | the use of pesticides is important for growing crops and protecting human health by reducing the prevalence of targeted pest species. however, less attention is given to the potential unintended effects on nontarget species, including taxonomic groups that are of current conservation concern. one issue raised in recent years is the potential for pesticides to become more lethal in the presence of predatory cues, a phenomenon observed thus far only in the laboratory. a second issue is whether pes ... | 2012 | 22611860 |
| predator mediated selection and the impact of developmental stage on viability in wood frog tadpoles (rana sylvatica). | complex life histories require adaptation of a single organism for multiple ecological niches. transitions between life stages, however, may expose individuals to an increased risk of mortality, as the process of metamorphosis typically includes developmental stages that function relatively poorly in both the pre- and post-metamorphic habitat. we studied predator-mediated selection on tadpoles of the wood frog, rana sylvatica, to identify this hypothesized period of differential predation risk a ... | 2011 | 22151372 |
| investigation of road salts and biotic stressors on freshwater wetland communities. | the application of road deicing salts has led to the salinization of freshwater ecosystems in northern regions worldwide. increased chloride concentrations in lakes, streams, ponds, and wetlands may negatively affect freshwater biota, potentially threatening ecosystem services. in an effort to reduce the effects of road salt, operators have increased the use of salt alternatives, yet we lack an understanding of how these deicers affect aquatic communities. we examined the direct and indirect eff ... | 2017 | 27939632 |
| ecological stoichiometry quantitatively predicts responses of tadpoles to a food quality gradient. | ecological stoichiometry (es) uses elemental ratios and mass balance to explain organismal growth, an important parameter in ecological systems. in this study, we tested quantitative predictions of the es "minimal model" for the growth rates of two tadpole species (wood frogs, lithobates sylvaticus and american toads, anaxyrus americanus), by manipulating light and the quality of a leaf litter mixture in a seminatural mesocosm experiment. we predicted that wood frogs, which consume leaf litter a ... | 2015 | 26405733 |
| variation in anti-parasite behaviour and infection among larval amphibian species. | along with immune defences, many animals exhibit effective anti-parasite behaviours such as parasite avoidance and removal that influence their susceptibility to infection. host ecology and life history influence investment into comparatively fixed defences such as innate immunity but may affect the strength of anti-parasite behaviours as well. we investigated activity levels in five different species of larval amphibian with varying life histories and ecology in control, novel food stimulus, an ... | 2014 | 24337712 |
| changes in breeding phenology of eastern ontario frogs over four decades. | global climate change has been implicated in phenological shifts for a variety of taxa. amphibian species in particular are sensitive to changes in their environment due to their biphasic life history and restricted reproductive requirements. previous research has shown that not all temperate amphibian species respond similarly to the same suite of climatic or environmental cues, nor are individual species necessarily uniform in their responses across their range. we examined both the timing of ... | 2013 | 23610628 |
| roundup and amphibians: the importance of concentration, application time, and stratification. | the widespread use of pesticides raises the possibility that non-target organisms might also be affected. to assess this, the traditional approach has been to conduct short-term laboratory experiments spanning a range of lethal concentrations and some longer-duration experiments at sublethal concentrations. while this approach has been very useful, less attention has been paid to the timing of exposure and the impacts of multiple, small exposures versus single, large exposures. we examined the r ... | 2010 | 20821659 |
| differential effects of malathion and nitrate exposure on american toad and wood frog tadpoles. | organisms living in aquatic ecosystems are increasingly likely to be exposed to multiple pollutants at the same time due to the simultaneous use of several pesticides and fertilizers. we examined the single and interactive effects of environmentally realistic concentrations of nitrate and malathion on two species of tadpoles common in agricultural regions of the united states-the american toad (bufo americanus) and the wood frog (rana sylvatica)-using a fully factorial mesocosm experiment that c ... | 2011 | 20556601 |
| toxicity of road salt to nova scotia amphibians. | the deposition of chemical pollutants into roadside wetlands from runoff is a current environmental concern. in northern latitudes, a major pollutant in runoff water is salt (nacl), used as de-icing agents. in this study, 26 roadside ponds were surveyed for amphibian species richness and chloride concentration. acute toxicity tests (lc(50)) were performed on five locally common amphibian species using a range of environmentally significant nacl concentrations. field surveys indicated that spotte ... | 2009 | 18684543 |
| microcosm investigations of stormwater pond sediment toxicity to embryonic and larval amphibians: variation in sensitivity among species. | stormwater ponds have become common features of modern development and often represent significant amounts of open space in urbanized areas. although stormwater ponds may provide habitat for wildlife, factors responsible for producing variation in wildlife use of ponds have received limited attention. to investigate the role of variation in species tolerances of pollutants in structuring pond-breeding amphibian assemblages, we exposed species tolerant (bufo americanus) and not tolerant (rana syl ... | 2008 | 18023947 |
| helminth communities in five species of sympatric amphibians from three adjacent ephemeral ponds in southeastern wisconsin. | representatives of 5 amphibian species (313 individuals), including eastern american toads (bufo americanus), wood frogs (rana sylvatica), spring peepers (pseudacris crucifer), blue-spotted salamanders (ambystoma laterale), and central newts (notophthalmus viridescens louisianensis), were collected from 3 ephemeral ponds during spring 1994, and they were inspected for helminth parasites. the component communities of anurans were more diverse than those of caudates. infracommunities of all host s ... | 2007 | 17918353 |
| density dependence in the terrestrial life history stage of two anurans. | populations of species with complex life cycles have the potential to be regulated at multiple life history stages. however, research tends to focus on single stage density-dependence, which can lead to inaccurate conclusions about population regulation and subsequently hinder conservation efforts. in amphibians, many studies have demonstrated strong effects of larval density and have often assumed that populations are regulated at this life history stage. however, studies examining density regu ... | 2007 | 17622562 |
| amphibian embryo and parental defenses and a larval predator reduce egg mortality from water mold. | water molds attack aquatic eggs worldwide and have been associated with major mortality events in some cases, but typically only in association with additional stressors. we combined field observations and laboratory experiments to study egg stage defenses against pathogenic water mold in three temperate amphibians. spotted salamanders (ambystoma maculatum) wrap their eggs in a protective jelly layer that prevents mold from reaching the embryos. wood frog (rana sylvatica) egg masses have less je ... | 2006 | 17089665 |
| the tactile-stimulated startle response of tadpoles: acceleration performance and its relationship to the anatomy of wood frog (rana sylvatica), bullfrog (rana catesbeiana), and american toad (bufo americanus) tadpoles. | i described the tactile-stimulated startle response (tsr) of wood frog (rana sylvatica), bullfrog (rana catesbeiana), and american toad (bufo americanus) tadpoles. one purpose was to rank species in terms of maximum acceleration performance. also, i tested whether anatomical indicators of performance potential were predictive of realized performance. tsrs were elicited in a laboratory setting, filmed at 250 hz, and digitally analyzed. tsrs began with two, initial body curls during which tadpoles ... | 2006 | 16493644 |
| the lethal impacts of roundup and predatory stress on six species of north american tadpoles. | the decline in amphibians across the globe has sparked a search for the causes, and recent evidence suggests a connection with pesticides. however, for most pesticides, tests on amphibians are rare and conducted only for short durations (1 to 4 days) and without natural stressors. recent studies have discovered that the stress of predator cues in the water can make insecticides much more lethal to larval amphibians, but it is unknown whether this phenomenon can be generalized to other types of p ... | 2005 | 15886853 |
| ontogeny, phylogeny, and morphology in anuran larvae: morphometric analysis of cranial development and evolution in rana tadpoles (anura: ranidae). | comparative studies of chondrocranial morphology in larval anurans are typically qualitative in nature, focusing primarily on discrete variation or gross differences in the size or shape of individual structures. detailed data on chondrocranial allometry are currently limited to only two species, rana sylvatica and bufo americanus. this study uses geometric morphometric and multivariate statistical analyses to examine interspecific variation in both larval chondrocranial shape and patterns of on ... | 2005 | 15688441 |
| effects of chlorinated solvents on four species of north american amphibians. | tetrachloroethylene (pce), a dry cleaning and degreasing solvent, can enter groundwater through accidental leaks or spills, and concentrations as high as 75 mg/l have been reported in canadian aquifers. amphibians in wetlands receiving contaminated groundwater may be exposed to pce and its degradation products, but little information is available on the impacts of these compounds on indigenous amphibian species. acute (96-h static renewal) exposures to pce and its major degradation products, tri ... | 2004 | 15346783 |
| survivorship patterns of larval amphibians exposed to low concentrations of atrazine. | amphibians can be exposed to contaminants in nature by many routes, but perhaps the most likely route is agricultural runoff in amphibian breeding sites. this runoff results in high-level pulses of pesticides. for example, atrazine, the most widely used pesticide in the united states, can be present at several parts per million in agricultural runoff. however, pesticide levels are likely to remain in the environment at low levels for longer periods. nevertheless, most studies designed to examine ... | 2004 | 15238276 |
| effects of atrazine on embryos, larvae, and adults of anuran amphibians. | we examined the effects of atrazine (0-20 mg/l) on embryos, larvae, and adult anuran amphibian species in the laboratory. atrazine treatments did not affect hatchability of embryos or 96-h posthatch mortality of larvae of rana pipiens, rana sylvatica, or bufo americanus. furthermore, atrazine had no effect on swimming speed (measured for r. pipiens only). however, there was a dose-dependent increase in deformed larvae of all three species with increasing atrazine concentration. in adult r. pipie ... | 2001 | 11345452 |
| effects of boron and nitrate on hatching success of amphibian eggs. | as part of a land-application wastewater disposal system in central pennsylvania, vernal ponds are commonly exposed to wastewater effluent containing high levels of boron and nitrate. we examined the individual effects of these compounds on the eggs of amphibians breeding in these ponds. wood frog (rana sylvatica), jefferson salamander (ambystoma jeffersonianum), spotted salamander (a. maculatum), and american toad (bufo americanus) eggs were exposed to boron (0, 50, and 100 mg l-1) and nitrate ... | 1998 | 9776779 |
| freeze tolerance and intolerance as strategies of winter survival in terrestrially-hibernating amphibians. | the ability to tolerate extracellular freezing as an adaptation for winter survival was tested in seven species of terrestrially-hibernating amphibians found in eastern canada. all species had only moderate supercooling abilities, with whole animal supercooling points of -1.5 to -3 degrees c. two salamander species, plethodon cinereus and ambystoma laterale, and the toad, bufo americanus, were freezing intolerant and were killed when frozen for 24 hr at temperatures just below their supercooling ... | 1986 | 2870854 |
| post-metamorphic change in activity metabolism of anurans in relation to life history. | newly-metamorphosed individuals of some species of frogs and toads differ from adults in behavior, ecology, and physiology. these differences may be related to broader patterns of the life histories of different species of frogs. in particular, the length of larval life and the size of a frog at metamorphosis appear to be significant factors in post-metamorphic ontogenetic change. these changes in performance are associated with rapid post-metamorphic increases in oxygen transport capacity. bufo ... | 1984 | 28312123 |
| blood parasites of amphibians from algonquin park, ontario. | during a 5 wk period beginning may 25, 1983, 329 amphibians, which included specimens of rana catesbeiana shaw, rana clamitans latreille, rana septentrionalis baird, rana sylvatica leconte, hyla crucifer wied, bufo americanus holbrook, and plethodon cinereus green, from lake sasajewun, algonquin park, ontario, canada were examined for blood parasites. the prevalences of species of trypanosoma, haemogregarina, lankesterella, babesiasoma, and thrombocytozoons in these amphibians were determined. t ... | 1984 | 6492319 |
| myiasis by lucilia silvarum (calliphoridae) in amphibian species in boreal alberta, canada. | we report myiasis by lucilia silvarum with an overall prevalence of 0.9% in amphibian populations in boreal alberta. in the period 1998--1999, we documented l. silvarum infestations in wild populations of wood frog (rana sylvatica), boreal chorus frog (pseudacris maculata), boreal toad (bufo boreas boreas), and canadian toad (b. hemiophrys). we believe this is the first record of this parasite from boreal and canadian toads. almost all previous records of l. silvarum parasitism in north america ... | 2008 | 18576743 |
| expression of freeze-responsive proteins, fr10 and li16, from freeze-tolerant frogs enhances freezing survival of bmn insect cells. | to date, two novel freeze-responsive proteins, fr10 and li16, have been discovered in the wood frog, rana sylvatica, and likely support freezing survival. although previous studies have established tissue distribution of each protein, there have been no studies that explore their functional consequences in intolerant cells. to assess the ability of fr10 and li16 to confer freeze tolerance, we transfected each protein into a freeze-intolerant silkworm cell line (bmn). selected controls were the t ... | 2013 | 23657819 |
| suspension feeding of anuran larvae at low concentrations of chlorella algae (amphibia, anura). | ingestion and filtering rates in larval xenopus laevis, bufo calamita, rana temporia and bufo bufo fed suspensions of chlorella fusca were investigated. concentrations were measured with a coulter counter. (1) for all species, filtration occurred at concentrations far below those reported by other authors for rana sylvatica feeding on chlorella pyrenoidosa. for bufo bufo, only larvae near metamorphosis showed ingestion at low particle concentrations. since buccopharyngeal ventilation continues e ... | 1990 | 28312552 |
| effects of cutrine-plus® algaecide and predators on wood frog (lithobates sylvaticus) tadpole survival and growth. | copper contamination is increasing in many aquatic ecosystems. one mode by which copper can be introduced into aquatic ecosystems is as an algaecide, such as cutrine-plus®. using a mesocosm experiment, we examined the effects of cutrine-plus® on wood frog (lithobates sylvaticus) tadpoles. in addition, we examined how the presence of a nonnative predator the western mosquitofish (gambusia affinis) may interact with exposure to cutrine-plus®. exposure to our low and high cutrine-plus® treatments h ... | 2014 | 24943889 |
| sodium perchlorate disrupts development and affects metamorphosis- and growth-related gene expression in tadpoles of the wood frog (lithobates sylvaticus). | numerous endocrine disrupting chemicals can affect the growth and development of amphibians. we investigated the effects of a targeted disruption of the endocrine axes modulating development and somatic growth. wood frog (lithobates sylvaticus) tadpoles were exposed for 2weeks (from developmental gosner stage (gs) 25 to gs30) to sodium perchlorate (sp, thyroid inhibitor, 14mg/l), estradiol (e2, known to alter growth and development, 200nm) and a reduced feeding regime (rf, to affect growth and d ... | 2015 | 25623150 |
| detecting small environmental differences: risk-response curves for predator-induced behavior and morphology. | most organisms possess traits that are sensitive to changes in the environment (i.e., plastic traits) which results in the expression of environmentally induced polymorphisms. while most phenotypically plastic traits have traditionally been treated as threshold switches between induced and uninduced states, there is growing evidence that many traits can respond in a continuous fashion. in this experiment we exposed larval anurans (wood frog tadpoles, rana sylvatica) to an increasing gradient of ... | 2008 | 17922146 |
| effects of road salt on larval amphibian susceptibility to parasitism through behavior and immunocompetence. | large quantities of road salts are used for de-icing in temperate climates but often leach into aquatic ecosystems where they can cause harm to inhabitants, including reduced growth and survival. however, the implications of road salt exposure for aquatic animal susceptibility to pathogens and parasites have not yet been examined even though infectious diseases can significantly contribute to wildlife population declines. through a field survey, we found a range of nacl concentrations (50-560mg/ ... | 2017 | 28582700 |
| effects of host species and life stage on the helminth communities of sympatric northern leopard frogs (lithobates pipiens) and wood frogs (lithobates sylvaticus) in the sheyenne national grasslands, north dakota. | we studied helminth communities in sympatric populations of leopard frogs (lithobates pipiens) and wood frogs (lithobates sylvaticus) and assessed the effects of host species and life stage on helminth community composition and helminth species richness. we examined 328 amphibians including 218 northern leopard frogs and 110 wood frogs collected between april and august of 2009 and 2010 in the sheyenne national grasslands of southeastern north dakota. echinostomatid metacercariae were the most c ... | 2013 | 23409956 |
| an unforeseen chain of events: lethal effects of pesticides on frogs at sublethal concentrations. | the field of toxicology has traditionally assessed the risk of contaminants by using laboratory experiments and a range of pesticide concentrations that are held constant for short periods of time (1-4 days). from these experiments, one can estimate the concentration that causes no effect on survival. however, organisms in nature frequently experience multiple, applications of pesticides over time rather than a single constant concentration. in addition, organisms are embedded in ecological comm ... | 2008 | 18839767 |