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the effects of electrolytes and sugars on the erythrocytes of the turtle, chelydra serpentina. 194918108892
expression of putative sex-determining genes during the thermosensitive period of gonad development in the snapping turtle, chelydra serpentina.modes of sex determination are quite variable in vertebrates. the developmental decision to form a testis or an ovary can be influenced by one gene, several genes, environmental variables, or a combination of these factors. nevertheless, certain morphogenetic aspects of sex determination appear to be conserved in amniotes. here we clone fragments of nine candidate sex-determining genes from the snapping turtle chelydra serpentina, a species with temperature-dependent sex determination (tsd). we ...200718391536
detection of salmonellae in different turtle species within a headwater spring ecosystem.sediments and water from the slough arm of spring lake, the headwaters of the san marcos river, texas, usa, as well as swabs from biofilms on carapaces and from the cloacae of 18 common musk turtles (sternotherus odoratus), 21 red-eared sliders (trachemys scripta elegans), nine texas river cooters (pseudemys texana), one snapping turtle (chelydra serpentina serpentina), and three guadalupe spiny soft-shell turtles (apalone spinifera guadalupensis), caught at the same site, were analyzed for salm ...200818436690
formation and ossification of limb elements in trachemys scripta and a discussion of autopodial elements in turtles.though sequences of formation and ossification of bony elements have been described for many taxa, controversy surrounds the formation of limb elements in turtles. three hypotheses for patterns of formation of autopodial elements have been proposed, differing primarily in the origin of distal carpal/tarsal 3, the digital arch, and centrale 4. patterns of formation and ossification of limb elements are described for trachemys scripta. these patterns are compared to similar data for representative ...200818624573
carbon dioxide (co2) laser treatment of cutaneous papillomas in a common snapping turtle, chelydra serpentina.carbon dioxide (co2) laser was used to treat multiple cutaneous papillomas on an adult female common snapping turtle, chelydra serpentina serpentina. a combination of excisional and ablative techniques provided excellent intraoperative visibility and postoperative results due to the laser's unique ability to incise and vaporize soft tissue.200818634218
an outbreak of salmonella food poisoning at a snapping turtle restaurant. 200818653984
health assessment of free-ranging alligator snapping turtles (macrochelys temminckii) in georgia and florida.the alligator snapping turtle (macrochelys temminckii) is a large freshwater turtle endemic to river systems that drain into the gulf of mexico. turtle populations were sharply reduced by commercial harvest in the 1970s and 1980s; however, the species has yet to be protected under the endangered species act. while anthropogenic stressors such as habitat fragmentation and degradation and illegal capture continue to threaten populations, the degree to which disease may be contributing to any decli ...200818689653
accumulation and maternal transfer of polychlorinated biphenyls in snapping turtles of the upper hudson river, new york, usa.we conducted field studies over three years to assess body burdens and maternal transfer of polychlorinated biphenyls (pcbs) as well as indices of sexual dimorphism in snapping turtles (chelydra serpentina) of the upper hudson river (ny, usa.) we collected adult turtles in areas known to be contaminated with pcbs and in nearby reference areas for measurement of body size, precloacal length, and penis size. we analyzed pcb concentrations in eggs collected over three years and in whole blood from ...200818699700
a new haemogregarina species of the alligator snapping turtle, macrochelys temminckii (testudines: chelydridae), in georgia and florida that produces macromeronts in circulating erythrocytes.haemogregarina macrochelysi n. sp. (apicomplexa: haemogregarinidae) of the alligator snapping turtle, macrochelys temminckii, is characterized by slender, recurved gamonts 29-35 x 3-4.5 microm, in which the anterior limb comprises 48-54% of the total length. the gamont nucleus, 5-7.5 x 2-5 microm, is situated at approximately midbody of the gamont. meronts typical of haemogregarina occupying erythrocytes have 3-8 small, compact nuclei and are 13-17 x 4.5-9 microm. erythrocytic meronts that conta ...200919245282
cross-reactivity of a polyclonal antibody against chinemys reevesii vitellogenin with the vitellogenins of other turtle species: chelydra serpentina , macrochelys temminckii , and pelodiscus sinensis.vitellogenin (vtg), a yolk-precursor protein in oviparous vertebrates, is a useful biomarker for reproductive physiology and environmental estrogenic pollution. to examine interspecific applicability of an enzyme-linked immunosorbent assay (elisa) for quantifying chinemys reevesii vtg, we observed cross-reactivity between a polyclonal antibody against chinemys reevesii vtg and the vtgs from other turtle species: chelydra serpentina (chelydridae), macrochelys temminckii (chelydridae), and pelodis ...200819267600
lipid metabolism during embryonic development of the common snapping turtle, chelydra serpentina.the metabolism of lipids and fatty acids during embryonic development of chelydra serpentina (common snapping turtle) was investigated. substantial changes in lipid class and fatty acid composition occurred as lipids were transferred from the yolk to the yolk sac membrane (ysm) and then to the brain, eyes, heart, and lungs of the hatchling. lipids were hydrolyzed in the yolk prior to transport to the ysm, shown by a large increase in free fatty acids (ffas) during the second half of development. ...200919416694
the platelet-derived growth factor signaling system in snapping turtle embryos, chelydra serpentina: potential role in temperature-dependent sex determination and testis development.the platelet-derived growth factor (pdgf) signaling system is known to play a significant role during embryonic and postnatal development of testes in mammals and birds. in contrast, genes that comprise the pdgf system in reptiles have never been cloned or studied in any tissue, let alone developing gonads. to explore the potential role of pdgf ligands and their receptors during embryogenesis, we cloned cdna fragments of pdgf-a, pdgf-b, and receptors pdgfr-alpha and pdgfr-beta in the snapping tu ...200919523392
lack of biological effects of water accommodated fractions of chemically- and physically-dispersed oil on molecular, physiological, and behavioral traits of juvenile snapping turtles following embryonic exposure.snapping turtle (chelydra serpentina) eggs were exposed to two concentrations of chemically- or physically-dispersed water accommodated fractions of weathered arabian light crude oil (low=0.5 and high=10 g oil/l water). solutions were passed through nest substrate to simulate alterations in composition during percolation to egg depth. hatchlings were raised for 13 months during which numerous endpoints were measured. prior to percolation, total pah ("tpah"; the sum of 52 pahs measured) in physic ...200919631965
helminth infracommunities of the common snapping turtle (chelydra serpentina serpentina) from westhampton lake, virginia.patterns of infracommunity similarity were examined for 27 male and 6 female common snapping turtles, chelydra serpentina serpentina, collected from westhampton lake on the campus of the university of richmond in richmond, virginia, during the summer months of 1979 and 1980. patterns of infracommunity similarity based on parasite abundance emphasized differences between years and between host sexes. patterns of similarity based on parasite presence or absence emphasized differences among the mon ...200919658450
latent mortality of juvenile snapping turtles from the upper hudson river, new york, exposed maternally and via the diet to polychlorinated biphenyls (pcbs).we conducted a factorial experiment to compare sublethal and lethal responses of juvenile snapping turtles exposed maternally and/or through the diet to polychlorinated biphenyls (pcbs) over 14 months posthatching. maternal exposure did not affect embryonic development or hatching success. thyrosomatic indices were not influenced by treatments, although hepatosomatic indices were lower in animals having been exposed to pcbs maternally relative to those having been exposed both maternally and via ...200919731717
parent-offspring conflict and selection on egg size in turtles.the trade-off between offspring size and number can present a conflict between parents and their offspring. because egg size is constrained by clutch size, the optimal egg size for offspring fitness may not always be equivalent to that which maximizes parental fitness. we evaluated selection on egg size in three turtle species (apalone mutica, chelydra serpentina and chrysemys picta) to determine if optimal egg sizes differ between offspring and their mothers. although hatching success was gener ...200919796084
fourteen nuclear genes provide phylogenetic resolution for difficult nodes in the turtle tree of life.advances in molecular biology have expanded our understanding of patterns of evolution and our ability to infer phylogenetic relationships. despite many applications of molecular methods in attempts at resolving the evolutionary relationships among the major clades of turtles, some nodes in the tree have proved to be extremely problematic and have remained unresolved. in this study, we use 14 nuclear loci to provide an in depth look at several of these troublesome nodes and infer the systematic ...201019913628
physiology of hibernation under the ice by turtles and frogs.successful overwintering under ice by an air-breathing vertebrate requires either effective aquatic respiration if dissolved o(2) is available or the capacity for prolonged anaerobic metabolism if o(2) supplies are limiting. frogs can remain aerobic for many weeks when submerged at low temperature, even at water po(2) as low as 30 mmhg, but are unable to survive even 1 week in anoxic water. fuel reserves of hibernating frogs limit aerobic submergence, whereas acidosis may limit anoxic submergenc ...201020535765
structure of the newly found green turtle egg-white ribonuclease.marine green turtle (chelonia mydas) egg-white ribonuclease (gtrnase) was crystallized from 1.1 m ammonium sulfate ph 5.5 and 30% glycerol using the sitting-drop vapour-diffusion method. the structure of gtrnase has been solved at 1.60 a resolution by the molecular-replacement technique using a model based on the structure of rnase 5 (murine angiogenin) from mus musculus (46% identity). the crystal belonged to the monoclinic space group c2, with unit-cell parameters a = 86.271, b = 34.174, c = 3 ...201020606267
temperature effects on snapping performance in the common snapper chelydra serpentina (reptilia, testudines).studies on the effect of temperature on whole-animal performance traits other than locomotion are rare. here we investigate the effects of temperature on the performance of the turtle feeding apparatus in a defensive context. we measured bite force and the kinematics of snapping in the common snapping turtle (chelydra serpentina) over a wide range of body temperatures. bite force performance was thermally insensitive over the broad range of temperatures typically experienced by these turtles in ...201121137093
an egg injection technique to evaluate the effect of polychlorinated biphenyls on the hatching success of the snapping turtle (chelydra serpentina serpentina).embryos of oviparous organisms are exposed to contaminants by two pathways: contaminant uptake from the surrounding environment, and the transfer from female to offspring (maternal transfer). the initial source of contaminant exposure for most embryos is likely to be maternal transfer; therefore, maternal transfer studies are critical in determining the effects of contaminants on future populations. injection of contaminants directly into eggs is one route of experimental contaminant exposure th ...201121191884
mercury concentrations in snapping turtles (chelydra serpentina) correlate with environmental and landscape characteristics.mercury (hg) deposited onto the landscape can be transformed into methylmercury (mehg), a neurotoxin that bioaccumulates up the aquatic food chain. here, we report on hg concentrations in snapping turtles (chelydra serpentina) across new york state, usa. the objectives of this study were to: (1) test which landscape, water, and biometric characteristics correlate with total hg (thg) concentrations in snapping turtles; and (2) determine whether soft tissue thg concentrations correlate with scute ...201121688194
multi-scale hierarchy of chelydra serpentina: microstructure and mechanical properties of turtle shell.carapace, the protective shell of a freshwater snapping turtle, chelydra serpentina, shields them from ferocious attacks of their predators while maintaining light-weight and agility for a swim. the microstructure and mechanical properties of the turtle shell are very appealing to materials scientists and engineers for bio-mimicking, to obtain a multi-functional surface. in this study, we have elucidated the complex microstructure of a dry chelydra serpentina's shell which is very similar to a m ...201121783154
replication and persistence of vhsv ivb in freshwater turtles.with the emergence of viral hemorrhagic septicemia virus (vhsv) strain ivb in the great lakes of north america, hatchery managers have become concerned that this important pathogen could be transmitted by animals other than fish. turtles are likely candidates because they are poikilotherms that feed on dead fish, but there are very few reports of rhabdovirus infections in reptiles and no reports of the fish rhabdoviruses in animals other than teleosts. we injected common snapping turtles chelydr ...201121790064
toxicity of pesticide and fertilizer mixtures simulating corn production to eggs of snapping turtles (chelydra serpentina).many reptiles oviposit in soils associated with agricultural landscapes. we evaluated the toxicity of a pesticide and fertilizer regime similar to those used in corn production in ontario on the survivorship of exposed snapping turtle (chelydra serpentina) eggs. the herbicides atrazine, dimethenamid, and glyphosate, the pyrethroid insecticide tefluthrin, and the fertilizer ammonia, were applied to clean soil, both as partial mixtures within chemical classes, as well as complete mixtures. eggs we ...201121831407
absorption of current use pesticides by snapping turtle (chelydra serpentina) eggs in treated soil.reptiles often breed within agricultural and urban environments that receive frequent pesticide use. consequently, their eggs and thus developing embryos may be exposed to pesticides. our objectives were to determine (i) if turtle eggs are capable of absorbing pesticides from treated soil, and (ii) if pesticide absorption rates can be predicted by their chemical and physical properties. snapping turtle (chelydra serpentina) eggs were incubated in soil that was treated with 10 pesticides (atrazin ...201121862099
Incidental nest predation in freshwater turtles: inter- and intraspecific differences in vulnerability are explained by relative crypsis.There has long been interest in the influence of predators on prey populations, although most predator-prey studies have focused on prey species that are targets of directed predator searching. Conversely, few have addressed depredation that occurs after incidental encounters with predators. We tested two predictions stemming from the hypothesis that nest predation on two sympatric freshwater turtle species whose nests are differentially prone to opportunistic detection-painted turtles (Chrysemy ...201122009341
highly elevated levels of perfluorooctane sulfonate and other perfluorinated acids found in biota and surface water downstream of an international airport, hamilton, ontario, canada.per- and poly-fluorinated compounds (pfcs), which include perfluorinated carboxylates (pfcas) and sulfonates (pfsas) and various precursors, are used in a wide variety of industrial, commercial and domestic products. this includes aqueous film forming foam (afff), which is used by military and commercial airports as fire suppressants. in a preliminary assessment prior to this study, very high concentrations (>1 ppm wet weight) of the pfsa, perfluorooctane sulfonate (pfos), were discovered in the ...201222208739
widespread reproductive variation in north american turtles: temperature, egg size and optimality.theory predicts the existence of an optimal offspring size that balances the trade-off between offspring fitness and offspring number. however, in wild populations of many species, egg size can still vary from year to year for unknown reasons. here, we hypothesize that among-year variation in population mean egg size of freshwater turtles is partly a consequence of their gonadal sensitivity to seasonal temperatures, a physiological mechanism which principally functions to synchronize reproductio ...201222541670
cutaneous fibroma in a captive common snapping turtle (chelydra serpentina).an adult female common snapping turtle (chelydra serpentina) had a mass on the plantar surface of the right forelimb that was removed surgically. microscopical examination revealed many spindle cells with mild anisocytosis and anisokaryosis and a surrounding collagenous stroma. there were no mitoses. immunohistochemistry showed that the spindle cells expressed vimentin, but not desmin. a diagnosis of cutaneous fibroma was made. tumours are reported uncommonly in chelonian species. cutaneous fibr ...201222578330
comparative effects of in ovo exposure to sodium perchlorate on development, growth, metabolism, and thyroid function in the common snapping turtle (chelydra serpentina) and red-eared slider (trachemys scripta elegans).perchlorate is a surface and groundwater contaminant found in areas associated with munitions and rocket manufacturing and use. it is a thyroid-inhibiting compound, preventing uptake of iodide by the thyroid gland, ultimately reducing thyroid hormone production. as thyroid hormones influence metabolism, growth, and development, perchlorate exposure during the embryonic period may impact embryonic traits that ultimately influence hatchling performance. we topically exposed eggs of red-eared slide ...201222871607
species specific differences in the in vitro metabolism of the flame retardant mixture, firemaster® bz-54.firemaster(®) bz-54 is a flame retardant additive and consists of a brominated benzoate (2-ethylhexyl 2,3,4,5-tetrabromobenzoate; tbb) and a brominated phthalate (bis (2-ethylhexyl) 2,3,4,5-tetrabromophthalate; tbph). previous research has shown that fathead minnows exposed in vivo to firemaster(®) bz-54 accumulate tbb and tbph. this study examined the in vitro biotransformation potential of tbb and tbph in hepatic subcellular fractions (i.e., s9, microsomes and cytosol) in the fathead minnow, c ...201222889877
anatomy of the fully formed chondrocranium of emydura subglobosa (chelidae): a pleurodiran turtle.the chondrocranium is a cartilaginous structure that forms around and protects the brain and sensory organs of the head. through ontogeny, this skeletal structure may become more elaborate, remodeled and reabsorbed, and/or ossified. though considerable attention has been given to the formation of the chondrocranium and a great amount of data has been gathered on the development of this structure among many craniates, the anatomy of this structure in turtles often is neglected. we describe the ma ...201322972700
nondestructive indices of mercury exposure in three species of turtles occupying different trophic niches downstream from a former chloralkali facility.turtles are useful for studying bioaccumulative pollutants such as mercury (hg) because they have long life spans and feed at trophic levels that result in high exposure to anthropogenic chemicals. we compared total hg concentrations in blood and toenails of three species of turtles (chelydra serpentina, sternotherus odoratus, and graptemys geographica) with different feeding ecologies from locations up- and downstream of a superfund site in virginia, usa. mercury concentrations in turtle tissue ...201323010870
temperature-dependent sex determination modulates cardiovascular maturation in embryonic snapping turtles chelydra serpentina.we investigated sex differences in cardiovascular maturation in embryos of the snapping turtle chelydra serpentina, a species with temperature-dependent sex determination. one group of eggs was incubated at 26.5°c to produce males. another group of eggs was incubated at 26.5°c until embryos reached stage 17; eggs were then shifted to 31°c for 6 days to produce females, and returned to 26.5°c for the rest of embryogenesis. thus, males and females were at the same temperature when autonomic tone w ...201323125337
experimental exposure of eggs to polybrominated diphenyl ethers bde-47 and bde-99 in red-eared sliders (trachemys scripta elegans) and snapping turtles (chelydra serpentina) and possible species-specific differences in debromination.polybrominated diphenyl ethers (pbdes) are a bioaccumulative, persistent, and toxic class of flame retardants that can potentially impact turtles in natural habitats via exposure through maternal transfer. to simulate maternal transfer in the present study, pbde congeners bde-47 and bde-99 were topically applied to the eggshell and were allowed to diffuse into the egg contents of the red-eared slider (trachemys scripta elegans) and snapping turtle (chelydra serpentina). eggs were topically dosed ...201323147837
mercury exposure is associated with negative effects on turtle reproduction.mercury (hg), a ubiquitous and highly toxic bioaccumulative contaminant, can maternally transfer and elicit deleterious effects on adult reproduction and offspring phenotype in fish, amphibians, and birds. however, the effects of hg on reproduction remain largely unstudied in reptiles. we evaluated the consequences of maternally transferred hg on a long-lived aquatic omnivore, the common snapping turtle (chelydra serpentina). we collected eggs and tissues from gravid female turtles along a broad ...201323360167
non-destructive techniques for biomonitoring of spatial, temporal, and demographic patterns of mercury bioaccumulation and maternal transfer in turtles.mercury (hg) is a globally ubiquitous pollutant that has received much attention due to its toxicity to humans and wildlife. the development of non-destructive sampling techniques is a critical step for sustainable monitoring of hg accumulation. we evaluated the efficacy of non-destructive sampling techniques and assessed spatial, temporal, and demographic factors that influence hg bioaccumulation in turtles. we collected muscle, blood, nail, and eggs from snapping turtles (chelydra serpentina) ...201323500054
plasticity of cardiovascular function in snapping turtle embryos (chelydra serpentina): chronic hypoxia alters autonomic regulation and gene expression.reptile embryos tolerate large decreases in the concentration of ambient oxygen. however, we do not fully understand the mechanisms that underlie embryonic cardiovascular short- or long-term responses to hypoxia in most species. we therefore measured cardiac growth and function in snapping turtle embryos incubated under normoxic (n21; 21% o₂) or chronic hypoxic conditions (h10; 10% o₂). we determined heart rate (fh) and mean arterial pressure (pm) in acute normoxic (21% o₂) and acute hypoxic (10 ...201323552497
integrative demographic modeling reveals population level impacts of pcb toxicity to juvenile snapping turtles.a significant challenge in ecotoxicology and risk assessment lies in placing observed contaminant effects in a meaningful ecological context. polychlorinated biphenyls (pcbs) have been shown to affect juvenile snapping turtle survival and growth but the ecological significance of these effects is difficult to discern without a formal, population-level assessment. we used a demographic matrix model to explore the potential population-level effects of pcbs on turtles. our model showed that effects ...201424047552
toxicity of pesticides associated with potato production, including soil fumigants, to snapping turtle eggs (chelydra serpentina).turtles frequently oviposit in soils associated with agriculture and, thus, may be exposed to pesticides or fertilizers. the toxicity of a pesticide regime that is used for potato production in ontario on the survivorship of snapping turtle (chelydra serpentina) eggs was evaluated. the following treatments were applied to clean soil: 1) a mixture of the pesticides chlorothalonil, s-metolachlor, metribuzin, and chlorpyrifos, and 2) the soil fumigant metam sodium. turtle eggs were incubated in soi ...201424105794
halogenated phenolic compound determination in plasma and serum by solid phase extraction, dansylation derivatization and liquid chromatography-positive electrospray ionization-tandem quadrupole mass spectrometry.a robust, sensitive and accurate method was developed for the simultaneous determination in plasma and serum of suite a halogenated phenolic compounds (hpcs) for which several are known to persist in the environment and analytically pure standards are available. namely, 14 congeners of hydroxylated polybrominated diphenyl ethers (oh-pbdes), six congeners of hydroxylated polychlorinated biphenyls (oh-pcbs), pentachlorophenol, pentabromophenol and the flame retardant tetrabromobisphenol a (tbbpa). ...201324210890
reproductive physiology in eastern snapping turtles (chelydra serpentina) exposed to runoff from a concentrated animal feeding operation.the eastern snapping turtle (chelydra serpentina) is widely distributed throughout the eastern and central us and is a useful model organism to study land-use impacts on water quality. we compared the reproductive condition of turtles from a pond impacted by runoff from land applied with animal manure from a concentrated animal feeding operation (cafo) relative to animals from a control pond. turtles from the cafo site were heavier and had higher plasma concentrations of vitellogenin (vtg, mean ...201324502728
thermoregulatory behavior is widespread in the embryos of reptiles and birds.recent studies have demonstrated that thermoregulatory behavior occurs not only in posthatching turtles but also in turtles prior to hatching. does thermoregulatory behavior also occur in the embryos of other reptile and bird species? our experiments show that such behavior is widespread but not universal in reptile and bird embryos. we recorded repositioning within the egg, in response to thermal gradients, in the embryos of three species of snakes (xenochrophis piscator, elaphe bimaculata, and ...201424561606
high levels of perfluoroalkyl acids in sport fish species downstream of a firefighting training facility at hamilton international airport, ontario, canada.a recent study reported elevated concentrations of perfluorooctane sulfonic acid (pfos) and other perfluoroalkyl acids (pfaas) in surface water, snapping turtles, and amphipods in lake niapenco, downstream of hamilton international airport, ontario, canada. here, our goals were to 1) determine the extent of pfaa contamination in sport fish species collected downstream of the airport, 2) explore if the airport could be a potential source, and 3) compare fish pfos concentrations to consumption adv ...201424632327
taxonomic assessment of alligator snapping turtles (chelydridae: macrochelys), with the description of two new species from the southeastern united states.the alligator snapping turtle, macrochelys temminckii, is a large, aquatic turtle limited to river systems that drain into the gulf of mexico. previous molecular analyses using both mitochondrial and nuclear dna suggested that macrochelys exhibits significant genetic variation across its range that includes three distinct genetic assemblages (western, central, and eastern = suwannee). however, no taxonomic revision or morphological analyses have been conducted previously. in this study, we test ...201424869532
exogenous application of estradiol to eggs unexpectedly induces male development in two turtle species with temperature-dependent sex determination.steroid hormones affect sex determination in a variety of vertebrates. the feminizing effects of exposure to estradiol and the masculinizing effects of aromatase inhibition during development are well established in a broad range of vertebrate taxa, but paradoxical findings are occasionally reported. four independent experiments were conducted on two turtle species with temperature-dependent sex determination (chrysemys picta and chelydra serpentina) to quantify the effects of egg incubation tem ...201424954686
substrate color-induced melanization in eight turtle species from four chelonian groups.background color convergence of prey occurring through local adaptation or phenotypically plastic responses can reduce predation rates by visual predators. we assessed the capacity for substrate color-induced melanization in eight turtle species within the groups chelydridae, emydidae, kinosternidae, and trionychidae by rearing individuals on black or white substrates for 160 days. in all aquatic turtle species, integuments of the head and carapace of the individuals that were reared on a black ...201424993507
adjustments in cholinergic, adrenergic and purinergic control of cardiovascular function in snapping turtle embryos (chelydra serpentina) incubated in chronic hypoxia.adenosine is an endogenous nucleoside that acts via g-protein coupled receptors. in vertebrates, arterial or venous adenosine injection causes a rapid and large bradycardia through atrioventricular node block, a response mediated by adenosine receptors that inhibit adenylate cyclase and decrease cyclic amp concentration. chronic developmental hypoxia has been shown to alter cardioregulatory mechanisms in reptile embryos, but adenosine's role in mediating these responses is not known. we incubate ...201425106687
dietary exposure of bde-47 and bde-99 and effects on behavior, bioenergetics, and thyroid function in juvenile red-eared sliders (trachemys scripta elegans) and common snapping turtles (chelydra serpentina).juvenile red-eared sliders (trachemys scripta elegans) and snapping turtles (chelydra serpentina) were fed food dosed with brominated diphenyl ether-47 (bde-47) or bde-99 for 6 mo beginning approximately 9 mo posthatch. during the exposure period, measurements of growth, bioenergetics, and behavior were made; thyroid function and accumulation were quantified postexposure. whole-body concentrations of both congeners were lower in red-eared sliders compared with snapping turtles after 6 mo of expo ...201425210006
a risk assessment approach to manage inundation of elseya albagula nests in impounded waters: a win-win situation?a risk assessment process was used to trial the impact of potential new operating rules on the frequency of nest inundation for the white-throated snapping turtle, elseya albagula, in the impounded waters of the burnett river, queensland, australia. the proposed operating rules would increase the barrage storage level during the turtle nesting season (may-july) and then would be allowed to reduce to a lower level for incubation for the rest of the year. these proposed operating rules reduce rate ...201525432451
a mycoplasma species of emydidae turtles in the northeastern usa.mycoplasma infections can cause significant morbidity and mortality in captive and wild chelonians. as part of a health assessment of endangered bog turtles (glyptemys muhlenbergii) in the northeastern us, choanal and cloacal swabs from these and other sympatric species, including spotted turtles (clemmys guttata), eastern box turtles (terrapene carolina carolina), wood turtles (glyptemys insculpta), and common snapping turtles (chelydra serpentina) from 10 sampling sites in the states (us) of d ...201525574806
molecular and morphological differentiation of testes and ovaries in relation to the thermosensitive period of gonad development in the snapping turtle, chelydra serpentina.ambient temperatures during embryonic development determine gonadal sex in many reptiles. the temperature sensitive period for sex determination has been defined by shifting eggs between female- and male-producing temperatures in a few species. this phase spans 20-35% of embryogenesis in most species, which makes it difficult to define the mechanisms that transduce temperature into a signal for ovarian versus testicular development. we present an extensive set of studies that define a brief peri ...201525662229
atrazine and glyphosate dynamics in a lotic ecosystem: the common snapping turtle as a sentinel species.atrazine and glyphosate are two of the most common pesticides used in the us midwest that impact water quality via runoff, and the common snapping turtle (chelydra serpentina) is an excellent indicator species to monitor these pesticides especially in lotic systems. the goals of this study were to (1) quantify atrazine, the atrazine metabolite diaminochlorotriazine (dact), and glyphosate burdens in common snapping turtle tissue from individuals collected within the embarras river in illinois; (2 ...201525678354
critical windows of cardiovascular susceptibility to developmental hypoxia in common snapping turtle (chelydra serpentina) embryos.environmental conditions fluctuate dramatically in some reptilian nests. however, critical windows of environmental sensitivity for cardiovascular development have not been identified. continuous developmental hypoxia has been shown to alter cardiovascular form and function in embryonic snapping turtles (chelydra serpentina), and we used this species to identify critical periods during which hypoxia modifies the cardiovascular phenotype. we hypothesized that incubation in 10% o2 during specific ...201525730266
evaluating recent taxonomic changes for alligator snapping turtles (testudines: chelydridae).the alligator snapping turtle (macrochelys temminckii troost in harlan 1835, sensu lato) has been historically treated as a single, wide-ranging species, until a recently published paper by thomas et al. (2014; hereafter thomas et al.) analyzed variation in morphology and mitochondrial dna sequence data to describe two new species of macrochelys: the apalachicola alligator snapping turtle (macrochelys apalachicolae thomas, granatosky, bourque, krysko, moler, gamble, suarez, leone & roman 2014) a ...201525947748
spontaneous magnetic alignment by yearling snapping turtles: rapid association of radio frequency dependent pattern of magnetic input with novel surroundings.we investigated spontaneous magnetic alignment (sma) by juvenile snapping turtles using exposure to low-level radio frequency (rf) fields at the larmor frequency to help characterize the underlying sensory mechanism. turtles, first introduced to the testing environment without the presence of rf aligned consistently towards magnetic north when subsequent magnetic testing conditions were also free of rf ('rf off → rf off'), but were disoriented when subsequently exposed to rf ('rf off → rf on'). ...201525978736
comparative analysis of glucagonergic cells, glia, and the circumferential marginal zone in the reptilian retina.retinal progenitors in the circumferential marginal zone (cmz) and müller glia-derived progenitors have been well described for the eyes of fish, amphibians, and birds. however, there is no information regarding a cmz and the nature of retinal glia in species phylogenetically bridging amphibians and birds. the purpose of this study was to examine the retinal glia and investigate whether a cmz is present in the eyes of reptilian species. we used immunohistochemical analyses to study retinal glia, ...201626053997
an appraisal of the use of an infrared digital monitoring system for long-term measurement of heart rate in reptilian embryos.measurement of heart rate (fh) in embryonic reptiles has previously imposed some degree of invasive treatment on the developing embryo. recently a non-invasive technique of fh detection from intact eggs was developed for commercial avian breeders and has since been used in biological research. this device uses infrared light, enabling it to detect heartbeats in very early embryos. however, infrared light is a source of heat and extended enclosure of an egg in the device is likely to affect tempe ...201526086361
deaths in bellinger river snapping turtles. 201526211039
snapping turtles (chelydra serpentina) from canadian areas of concern across the southern laurentian great lakes: chlorinated and brominated hydrocarbon contaminants and metabolites in relation to circulating concentrations of thyroxine and vitamin a.the metabolites of polychlorinated biphenyls (pcbs) and polybrominated diphenyl ethers (pbdes), as well as other halogenated phenolic contaminants (hpcs) have been shown to have endocrine-disrupting properties, and have been reported with increasing frequency in the blood of wildlife, and mainly in mammals and birds. however, little is known about the persistence, accumulation and distribution of these contaminants in long-lived freshwater reptiles. in the present study, in addition to a large s ...201526519832
phenotypic plasticity in the common snapping turtle (chelydra serpentina): long-term physiological effects of chronic hypoxia during embryonic development.studies of embryonic and hatchling reptiles have revealed marked plasticity in morphology, metabolism, and cardiovascular function following chronic hypoxic incubation. however, the long-term effects of chronic hypoxia have not yet been investigated in these animals. the aim of this study was to determine growth and postprandial o2 consumption (v̇o2), heart rate (fh), and mean arterial pressure (pm, in kpa) of common snapping turtles (chelydra serpentina) that were incubated as embryos in chroni ...201626608655
body burdens of heavy metals in lake michigan wetland turtles.tissue heavy metal concentrations in painted (chrysemys picta) and snapping (chelydra serpentina) turtles from lake michigan coastal wetlands were analyzed to determine (1) whether turtles accumulated heavy metals, (2) if tissue metal concentrations were related to environmental metal concentrations, and (3) the potential for non-lethal sampling techniques to be used for monitoring heavy metal body burdens in freshwater turtles. muscle, liver, shell, and claw samples were collected from painted ...201626832725
a novel candidate gene for temperature-dependent sex determination in the common snapping turtle.temperature-dependent sex determination (tsd) was described nearly 50 years ago. researchers have since identified many genes that display differential expression at male- vs. female-producing temperatures. yet, it is unclear whether these genes (1) are involved in sex determination per se, (2) are downstream effectors involved in differentiation of ovaries and testes, or (3) are thermo-sensitive but unrelated to gonad development. here we present multiple lines of evidence linking cirbp to sex ...201626936926
post-hatching development of mitochondrial function, organ mass and metabolic rate in two ectotherms, the american alligator (alligator mississippiensis) and the common snapping turtle (chelydra serpentina).the ontogeny of endothermy in birds is associated with disproportionate growth of thermogenic organs and increased mitochondrial oxidative capacity. however, no similar study has been made of the development of these traits in ectotherms. for comparison, we therefore investigated the metabolism, growth and muscle mitochondrial function in hatchlings of a turtle and a crocodilian, two ectotherms that never develop endothermy. metabolic rate did not increase substantially in either species by 30 d ...201626962048
morphological study on the olfactory systems of the snapping turtle, chelydra serpentina.in this study, the olfactory system of a semi-aquatic turtle, the snapping turtle, has been morphologically investigated by electron microscopy, immunohistochemistry, and lectin histochemistry. the nasal cavity of snapping turtle was divided into the upper and lower chambers, lined by the sensory epithelium containing ciliated and non-ciliated olfactory receptor neurons, respectively. each neuron expressed both gαolf, the α-subunit of g-proteins coupling to the odorant receptors, and gαo, the α- ...201627059760
embryonic common snapping turtles (chelydra serpentina) preferentially regulate intracellular tissue ph during acid-base challenges.the nests of embryonic turtles naturally experience elevated co2 (hypercarbia), which leads to increased blood pco2  and a respiratory acidosis, resulting in reduced blood ph [extracellular ph (phe)]. some fishes preferentially regulate tissue ph [intracellular ph (phi)] against changes in phe; this has been proposed to be associated with exceptional co2 tolerance and has never been identified in amniotes. as embryonic turtles may be co2 tolerant based on nesting strategy, we hypothesized that t ...201627091863
traumatic amputation of finger from an alligator snapping turtle bite.legend states that the alligator snapping turtle (macrochelys temminckii) should be handled with extreme caution as it has jaw strength powerful enough to bite a wooden broomstick in half. tales of bite injuries from what is the largest freshwater turtle in north america exist anecdotally, yet there are few descriptions of medical encounters for such. the risk of infection from reptilian bites to the hand in an aquatic environment warrants thorough antibiotic treatment in conjunction with hand s ...201627116923
high levels, partitioning and fish consumption based water guidelines of perfluoroalkyl acids downstream of a former firefighting training facility in canada.high levels of perfluoroalkyl acids (pfaas), especially perfluorooctane sulfonic acid (pfos), have been observed at locations in/around/downstream of the sites where pfos-based firefighting foam was used repeatedly for a prolonged period. in this study, we conducted a detailed investigation of pfaa contamination in the lake niapenco area in ontario, canada, where among the highest ever reported levels of pfos were recently measured in amphipods, fish and snapping turtle plasma. levels and distri ...201627302846
reptile embryos lack the opportunity to thermoregulate by moving within the egg.historically, egg-bound reptile embryos were thought to passively thermoconform to the nest environment. however, recent observations of thermal taxis by embryos of multiple reptile species have led to the widely discussed hypothesis that embryos behaviorally thermoregulate. because temperature affects development, such thermoregulation could allow embryos to control their fate far more than historically assumed. we assessed the opportunity for embryos to behaviorally thermoregulate in nature by ...201627322129
epinephrine or gv-26 electrical stimulation reduces inhalant anesthestic recovery time in common snapping turtles (chelydra serpentina).prolonged anesthetic recovery times are a common clinical problem in reptiles following inhalant anesthesia. diving reptiles have numerous adaptations that allow them to submerge and remain apneic for extended periods. an ability to shunt blood away from pulmonary circulation, possibly due to changes in adrenergic tone, may contribute to their unpredictable inhalant anesthetic recovery times. therefore, the use of epinephrine could antagonize this response and reduce recovery time. gv-26, an acu ...201627468022
effects of life-history requirements on the distribution of a threatened reptile.survival and reproduction are the two primary life-history traits essential for species' persistence; however, the environmental conditions that support each of these traits may not be the same. despite this, reproductive requirements are seldom considered when estimating species' potential distributions. we sought to examine potentially limiting environmental factors influencing the distribution of an oviparous reptile of conservation concern with respect to the species' survival and reproducti ...201727488734
preferential intracellular ph regulation: hypotheses and perspectives.the regulation of vertebrate acid-base balance during acute episodes of elevated internal pco2  is typically characterized by extracellular ph (phe) regulation. changes in phe are associated with qualitatively similar changes in intracellular tissue ph (phi) as the two are typically coupled, referred to as 'coupled ph regulation'. however, not all vertebrates rely on coupled ph regulation; instead, some preferentially regulate phi against severe and maintained reductions in phe preferential phi ...201627489212
atrazine alters expression of reproductive and stress genes in the developing hypothalamus of the snapping turtle, chelydra serpentina.atrazine is an herbicide used to control broadleaf grasses and a suspected endocrine disrupting chemical. snapping turtles lay eggs between late may and early june, which could lead to atrazine exposure via field runoff. our goal was to determine whether a single exposure to 2ppb or 40ppb atrazine during embryogenesis could induce short- and long-term changes in gene expression within the hypothalamus of snapping turtles. we treated eggs with atrazine following sex determination and measured gen ...201627495953
determination of linear and cyclic volatile methylsiloxanes in blood of turtles, cormorants, and seals from canada.we measured the concentrations of linear and cyclic volatile methylsiloxanes (vms) concentrations in the blood plasma of turtles, cormorants, and seals collected from canadian freshwater and marine ecosystems. a modified quick, easy, cheap, effective, rugged, and safe (quechers) method was developed to quantify the levels of linear and cyclic vms in the plasma samples. the cyclic vms of hexamethylcyclotrisiloxane (d3), octamethylcyclotetrasiloxane (d4), decamethylcyclopentasiloxane (d5), and dod ...201727663360
ontogenetic shifts in the diet of plains hog-nosed snakes (heterodon nasicus) revealed by stable isotope analysis.wild snake diets are difficult to study using traditional methods, but stable isotopes offer several advantages, including integrating dietary information over time, providing data from individuals that have not fed recently, and avoiding bias towards slowly-digesting prey items. we used stable isotope signatures of carbon and nitrogen from scale tissue, red blood cells, and blood plasma to assess the diet of wild plains hog-nosed snakes (heterodon nasicus) in illinois. we developed bayesian mix ...201727692795
molecular and morphological characterization of a haemogregarine in the alligator snapping turtle, macrochelys temminckii (testudines: chelydridae).a severely underweight alligator snapping turtle macrochelys temminckii troost in harlan, 1835, was found near tyler, texas, and taken to the caldwell zoo. blood films were submitted to texas a&m university, college station, texas, for morphological and molecular identification of haemogregarine-like inclusions in the red blood cells. intraerythrocytic haemogregarina sp. forms were found on microscopic examination at a parasitemia of <1 %. the morphology and morphometric data for the forms indic ...201727807618
blood flukes of asiatic softshell turtles: revision of coeuritrema mehra, 1933 (digenea: schistosomatoidea) and a new species infecting chinese softshell turtles, pelodiscus sinensis (trionychidae), from vietnam.coeuritrema mehra, 1933, previously regarded as a junior subjective synonym of hapalorhynchus stunkard, 1922, herein is revised to include coeuritrema lyssimus mehra, 1933 (type species), coeuritrema rugatus (brooks et sullivan, 1981) comb. n., and coeuritrema platti roberts et bullard sp. n. these genera are morphologically similar by having a ventral sucker, non-fused caeca, two testes, a pre-testicular cirrus sac, an intertesticular ovary, and a common genital pore that opens dorsally and in ...201627827338
phenotypic plasticity of nest timing in a post-glacial landscape: how do reptiles adapt to seasonal time constraints?life histories evolve in response to constraints on the time available for growth and development. nesting date and its plasticity in response to spring temperature may therefore be important components of fitness in oviparous ectotherms near their northern range limit, as reproducing early provides more time for embryos to complete development before winter. we used data collected over several decades to compare air temperature and nest date plasticity in populations of painted turtles and snap ...201727870008
metabolic rates are elevated and influenced by maternal identity during the early, yolk-dependent, post-hatching period in an estuarine turtle, the diamondback terrapin (malaclemys terrapin).non-genetic maternal effects, operating through a female's physiology or behavior, can influence offspring traits and performance. here we examined potential maternal influences on metabolic rates (mr) of offspring in an estuarine turtle, the diamondback terrapin (malaclemys terrapin). females and their eggs were collected from the field and the eggs incubated in the laboratory for subsequent measurement of mr of females, late-stage embryos, newly-hatched individuals that were nutritionally depe ...201727894885
genetic effects of landscape, habitat preference and demography on three co-occurring turtle species.expanding the scope of landscape genetics beyond the level of single species can help to reveal how species traits influence responses to environmental change. multispecies studies are particularly valuable in highly threatened taxa, such as turtles, in which the impacts of anthropogenic change are strongly influenced by interspecific differences in life history strategies, habitat preferences and mobility. we sampled approximately 1500 individuals of three co-occurring turtle species across a g ...201727997082
diatoms on the carapace of common snapping turtles: luticola spp. dominate despite spatial variation in assemblages.filamentous algae are often visible on the carapaces of freshwater turtles and these algae are dominated by a few species with varying geographic distributions. compared to filamentous algae, little is known about the much more speciose microalgae on turtles. our objectives were to compare the diatom flora on a single turtle species (the common snapping turtle, chelydra serpentina) across part of its range to examine spatial patterns and determine whether specific diatom taxa were consistently a ...201728192469
an immunohistochemical approach to identify the sex of young marine turtles.marine turtles exhibit temperature-dependent sex determination (tsd). during critical periods of embryonic development, the nest's thermal environment directs whether an embryo will develop as a male or female. at warmer sand temperatures, nests tend to produce female-biased sex ratios. the rapid increase of global temperature highlights the need for a clear assessment of its effects on sea turtle sex ratios. however, estimating hatchling sex ratios at rookeries remains imprecise due to the lack ...201728296279
the relationship of body size to survivorship of hatchling snapping turtles (chelydra serpentina): an evaluation of the "bigger is better" hypothesis.in many organisms, body size is positively correlated with traits that are presumably related to fitness. if directional selection frequently favors larger offspring (the "bigger is better" hypothesis), the results of such selection should be detectable with field experiments. we tested the "bigger is better" hypothesis in hatchling snapping turtles (chelydra serpentina) by conducting one long-term and three short-term experiments on the university of michigan e.s. george reserve in southeastern ...199928308562
aerial and aquatic oxygen uptake by freely-diving snapping turtles (chelydra serpentina).aerial oxygen consumption of unrestrained, freely-diving warm-and cold-acclimated snapping turtles, chelydra serpentina, was measured at 10, 20, and 30°c. also, simultaneous determinations of aerial and aquatic oxygen uptake by voluntarilydiving animals were made at 4 and 20°c. the standard rates of aerial oxygen consumption are equivalent in cold-and warm-acclimated animals in water and in cold-acclimated ones in air; these rates are all lower than those of warm-acclimated animals in air. thus ...198028309683
environmentally induced variation in body size of turtles hatching in natural nests.eggs from three snapping turtles (chelydra serpentina) were divided between two natural nests in a factorial experiment assessing the role of the nest environment as a cause for variation in body size and energy reserves of hatchlings at our study site in northcentral nebraska. nest # 1 was located in an unshaded area on the south side of a high sandhill, whereas nest #2 was located in an unshaded area on level ground. eggs in nest #1 increased in mass over the course of incubation, with eggs at ...199328313447
embryonic hypoxia programmes postprandial cardiovascular function in adult common snapping turtles (chelydra serpentina).reduced oxygen availability (hypoxia) is a potent stressor during embryonic development, altering the trajectory of trait maturation and organismal phenotype. we previously documented that chronic embryonic hypoxia has a lasting impact on the metabolic response to feeding in juvenile snapping turtles (chelydra serpentina). turtles exposed to hypoxia as embryos [10% o2 (h10)] exhibited an earlier and increased peak postprandial oxygen consumption rate, compared with control turtles [21% o2 (n21)] ...201728495871
high levels of maternally transferred mercury disrupt magnetic responses of snapping turtle hatchlings (chelydra serpentina).the earth's magnetic field is involved in spatial behaviours ranging from long-distance migration to non-goal directed behaviours, such as spontaneous magnetic alignment (sma). mercury is a harmful pollutant most often generated from anthropogenic sources that can bio-accumulate in animal tissue over a lifetime. we compared sma of hatchling snapping turtles from mothers captured at reference (i.e., low mercury) and mercury contaminated sites. reference turtles showed radio frequency-dependent sm ...201728501632
experimental evidence for the evolutionary significance of temperature-dependent sex determination.the evolutionary significance of sex-determining mechanisms, particularly temperature-dependent sex determination (tsd) in reptiles, has remained unresolved despite extensive theoretical work. to investigate the evolutionary significance of this unusual sex-determining mechanism, i incubated eggs of the common snapping turtle (chelydra serpentina) at a male-producing temperature (26°c), a female-producing temperature (30°c), and an intermediate temperature that produced both sexes about equally ...199528564861
among-family variation for environmental sex determination in reptiles.unlike birds and mammals, in many reptiles the temperature experienced by a developing embryo determines its gonadal sex. to understand how temperature-dependent sex determination (tsd) evolves, we must first determine the nature of genetic variation for sex ratio. here, we analyze among-family variation for sex ratio in three tsd species: the american alligator (alligator mississipiensis), the common snapping turtle (chelydra serpentina) and the painted turtle (chrysemys picta). significant fam ...199828565384
developmental cardiovascular physiology of the olive ridley sea turtle (lepidochelys olivacea).our understanding of reptilian cardiovascular development and regulation has increased substantially for two species the american alligator (alligator mississippiensis) and the common snapping turtle (chelydra serpentina) during the past two decades. however, what we know about cardiovascular maturation in many other species remains poorly understood or unknown. embryonic sea turtles have been studied to understand the maturation of metabolic function, but these studies have not addressed the ca ...201728642099
characterization of the foxl2 proximal promoter and coding sequence from the common snapping turtle (chelydra serpentina).sex is determined by temperature during embryogenesis in snapping turtles, chelydra serpentina. previous studies in this species show that dihydrotestosterone (dht) induces ovarian development at temperatures that normally produce males or mixed sex ratios. the feminizing effect of dht is associated with increased expression of foxl2, suggesting that androgens regulate transcription of foxl2. to test this hypothesis, we cloned the proximal promoter (1.6kb) and coding sequence for snapping turtle ...201728711355
morbidity and mortality of wild turtles at a north carolina wildlife clinic: a 10-year retrospective.the medical records from 1,847 wild turtle patients seen between 2005 and 2014 by the turtle rescue team at the north carolina state university college of veterinary medicine were analyzed. eastern box turtles (terrapene carolina carolina; n = 947), yellow-bellied sliders (trachemys scripta scripta; n = 301), cooters ( pseudemys spp.; n = 235), common snapping turtles (chelydra serpentina; n = 165), and eastern painted turtles (chrysemys picta; n = 93) made up 94.3% of all patients. patient admi ...201728920820
an unusual mortality event in johnstone river snapping turtles elseya irwini (johnstone) in far north queensland, australia.an unusual mortality event in johnstone river snapping turtles (elseya irwini) in far north queensland, australia, occurred during the summer months of december 2014 and january 2015. we report the data collected during the mortality event, including counts of sick and dead animals, clinical appearance and one necropsy.201728948624
pulmonary anatomy and a case of unilateral aplasia in a common snapping turtle (chelydra serpentina): developmental perspectives on cryptodiran lungs.the common snapping turtle (chelydra serpentina) is a well studied and broadly distributed member of testudines; however, very little is known concerning developmental anomalies and soft tissue pathologies of turtles and other reptiles. here, we present an unusual case of unilateral pulmonary aplasia, asymmetrical carapacial kyphosis, and mild scoliosis in a live adult c. serpentina. the detailed three-dimensional (3d) anatomy of the respiratory system in both the pathological and normal adult c ...201729063595
repeatability and sources of variation of the bacteria-killing assay in the common snapping turtle.research on reptile ecoimmunology lags behind that on other vertebrates, despite the importance of such studies for conservation and evolution. because the innate immune system is highly conserved across vertebrate lineages, assessments of its performance may be particularly useful in reptiles. the bacteria-killing assay requires a single, small blood sample and quantifies an individual's ability to kill microorganisms. the assay's construct validity and interpretability make it an attractive me ...201729356460
assessment of blood lead, zinc, and mercury concentrations and cholinesterase activity in captive-reared alligator snapping turtles ( macrochelys temminckii) in louisiana, usa.the alligator snapping turtle ( macrochelys temminckii) is a freshwater apex predator that has experienced severe population declines throughout its range due to historical overharvesting and habitat degradation. because of its long lifespan, high trophic level, and limited home range, it is a suitable sentinel species for monitoring environmental contaminants. in louisiana, us a pilot program aims to augment free-ranging populations by releasing captive-reared individuals. baseline values of po ...201829697311
a new method of estimating thermal performance of embryonic development rate yields accurate prediction of embryonic age in wild reptile nests.temperature has a strong effect on ectotherm development rate. it is therefore possible to construct predictive models of development that rely solely on temperature, which have applications in a range of biological fields. here, we leverage a reference series of development stages for embryos of the turtle chelydra serpentina, which was described at a constant temperature of 20 °c. the reference series acts to map each distinct developmental stage onto embryonic age (in days) at 20 °c. by exten ...201829801626
development of the turtle carapace: implications for the evolution of a novel bauplan.the chelonian carapace is composed of the endochondral ribs and vertebrae associated with a specialized dermis. the ribs are found in an aberrant position compared to those of all other tetrapods; they are superficial and dorsal to the limb girdles. this morphological arrangement, which constitutes the unique chelonian bauplan, is examined from a developmental perspective. embryos of chelydra serpentina were studied during stages of carapace development. tissue morphology, autoradiography, and i ...198929865619
functional mechanisms and histologic composition of the lingual appendage in the alligator snapping turtle, macroclemys temmincki (troost) (testudines: chelydridae).gross and microscopic examination of the lingual appendages of juvenile and adult alligator snapping turtles, macroclemys temmincki, shows that it is divided into an anterior horn, a body, and a posterior horn. lingual appendages of adults usually are more darkly pigmented than those of juveniles and melanocyte distribution is variable, resulting in a mottled appearance. the musculoskeletal components of the hyoid apparatus, presumably responsible for most of the motion displayed by the appendag ...198729914228
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