| convective oxygen transport during development in embryos of the snapping turtle chelydra serpentina. | this study investigated the maturation of convective oxygen transport in embryos of the snapping turtle (chelydra serpentina). measurements included: mass, oxygen consumption (v̇o2 ), heart rate, blood oxygen content and affinity and blood flow distribution at 50%, 70% and 90% of the incubation period. body mass increased exponentially, paralleled by increased cardiac mass and metabolic rate. heart rate was constant from 50% to 70% incubation but was significantly reduced at 90% incubation. hema ... | 2018 | 30065037 |
| 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 ... | 2018 | 29801626 |
| 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 ... | 2017 | 28501632 |
| 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)] ... | 2017 | 28495871 |
| survival of skin allografts following embryonic limb bud transplants in the turtle, chelydra serpentina. | allografts of skin were observed in chelydra serpentina. the response to these grafts was modified by a previous transplantation of a limb bud at an early embryonic stage. when the same donor was used for all transplants, the first skin graft was accepted by the host. a second skin graft, however, was rejected at about the rate of a simple first set allograft of skin. the animals were conditioned by the embryonic limb graft; this embryonic graft can be undergoing rejection at the same time a fir ... | 1974 | 30326680 |
| incidence and progress of rejection of embryonic limb bud transplants in the turtle, chelydra serpentina. | allografts of embryonic limb buds were grafted orthotopically on embryos of chelydra serpentina. donors were from a different geographic area, the same geographic area, or siblings. the initial indication of rejection was excessive sloughing of epidermis. this was followed by loss of muscle, claws and bone. early histological changes involved an infiltration of mononuclear or rejection cells primarily associated with small blood vessels of the connective tissue. subsequently, muscle and bone wer ... | 1974 | 30322221 |
| snapping turtle plea. | | 1973 | 17816278 |
| a new species of auridistomum (trematoda: auridistomidae) from snapping turtles of georgia. | | 1959 | 13802130 |
| 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 ... | 2017 | 27870008 |
| the complete mitochondrial genome of the enigmatic bigheaded turtle (platysternon): description of unusual genomic features and the reconciliation of phylogenetic hypotheses based on mitochondrial and nuclear dna. | the big-headed turtle (platysternon megacephalum) from east asia is the sole living representative of a poorly-studied turtle lineage (platysternidae). it has no close living relatives, and its phylogenetic position within turtles is one of the outstanding controversies in turtle systematics. platysternon was traditionally considered to be close to snapping turtles (chelydridae) based on some studies of its morphology and mitochondrial (mt) dna, however, other studies of morphology and nuclear ( ... | 2006 | 16464263 |
| agricultural land use creates evolutionary traps for nesting turtles and is exacerbated by mercury pollution. | the rate of anthropogenic habitat conversion often exceeds the rate of natural ecological and evolutionary processes, which sometimes creates mismatches between environmental cues and adaptive behaviors. in numerous species of aquatic turtles, nest site selection is primarily based on cues related to high solar exposure, which leads females to select sites where humans have disturbed habitat. these disturbed sites are often contaminated by pollutants, such as mercury. despite the fact that anthr ... | 2018 | 29962084 |
| further characterisation of haemocystidium chelodinae-like haemoproteidae isolated from the bellinger river snapping turtle (myuchelys georgesi). | the bellinger river snapping turtle (myuchelys georgesi) is endemic to australia and is confined to a highly restricted distribution in the bellinger river in new south wales. routine veterinary health examinations of 17 healthy turtles were undertaken, along with the collection and analysis of blood samples, during conservation efforts to save the species following a catastrophic population decline. microscopy analysis of blood films detected haemoproteidae parasites that morphologically resemb ... | 2020 | 31754857 |
| 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 ... | 2016 | 27489212 |
| 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 ... | 2016 | 27302846 |
| deaths in bellinger river snapping turtles. | | 2015 | 26211039 |
| 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'). ... | 2015 | 25978736 |
| 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 ... | 2014 | 24632327 |
| 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 ... | 2014 | 24047552 |
| 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 ... | 1987 | 29914228 |
| 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 ... | 2018 | 29697311 |
| contaminant residues in snapping turtle (chelydra s. serpentina) eggs from the great lakes-st. lawrence river basin (1999 to 2000). | to determine temporal and geographic variations of environmentally persistent pollutants, the concentrations of several contaminants were measured in snapping turtle eggs in 1999 and 2000. contaminants included polychlorinated biphenyls (pcbs), non- ortho pcbs, polychlorinated dibenzodioxins and furans, organochlorine pesticides, and total mercury. egg collection sites within the st. lawrence area of concern (aoc) and the territory of akwesasne included turtle creek, snye marsh, and raquette riv ... | 2004 | 15386150 |
| 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 ... | 1998 | 28565384 |
| 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 ... | 1995 | 28564861 |
| 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 ... | 1989 | 29865619 |
| 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 ... | 2017 | 29356460 |
| 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 ... | 2017 | 29063595 |
| 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 ... | 2017 | 28711355 |
| effects of incubation temperatures on sexual differentiation in the turtle, chelydra serpentina. | eggs of the common snapping turtle, chelydra serpentina, were incubated at constant temperatures ranging from 20°c to 30°c, at hatching, the oviducts were absent or incomplete in males; the testes were differentiated. in females at hatching, the oviduct was intact hut in some cases the gonad retained bisexual characteristics. three months after hatching, the ovary was differentiated and contained follicles. eggs incubated at 20°c and at 30°c developed into females in 100% of the cases. at 26°c, ... | 1976 | 30257532 |
| the survival of beat in the removed heart of the snapping turtle. | | 1916 | 17840076 |
| the development and homology of the chelonian carpus and tarsus. | the long-standing controversies involving the number and homologies of the elements of the carpus and tarsus of turtles are reviewed from a developmental perspective. the analysis is based on a detailed description of the chondrogenesis of the carpus and tarsus in the species chelydra serpentina and chrysemys picta. the first stage described is the differentiation of a y-shaped chondrogenetic condensation involving the humerus (femur)-radius/ ulna (tibia/fibula). this stage is followed by the ea ... | 1985 | 30005563 |
| determination of temperature sensitive stages for sexual differentiation of the gonads in embryos of the turtle, emys orbicularis. | in order to determine the temperature sensitive stages for sexual differentiation of the gonads in emys orbicularis, eggs of this turtle were shifted at different stages of embryonic development from the male-producing temperature of 25°c to the female-producing temperature of 30°c and reciprocally. based on the series of developmental stages described by yntema ('68) for chelydra serpentina, temperature begins to influence sexual differentiation of emys orbicularis at stage 16, a stage in which ... | 1981 | 30114859 |
| 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 ... | 2010 | 20535765 |
| temperature levels and periods of sex determination during incubation of eggs of chelydra serpentina. | eggs of chelydra serpentina were shifted during incubation between the female producing temperatures of 20°c or 30°c and the male producing temperature of 26°c. in the 20°c and 26°c combination, the stages during which incubation temperature determined sex were stage 14 through stage 16 (stages of normal series, yntema, '68). in the 30°c and 26°c combination, the temperature sensitive stages for sex determination were stage 14 through stage 19. incubation at 26°c throughout this period was neede ... | 1979 | 30205629 |
| 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 ... | 2009 | 19731717 |
| shell bone histology indicates terrestrial palaeoecology of basal turtles. | the palaeoecology of basal turtles from the late triassic was classically viewed as being semi-aquatic, similar to the lifestyle of modern snapping turtles. lately, this view was questioned based on limb bone proportions, and a terrestrial palaeoecology was suggested for the turtle stem. here, we present independent shell bone microstructural evidence for a terrestrial habitat of the oldest and basal most well-known turtles, i.e. the upper triassic proterochersis robusta and proganochelys quenst ... | 2007 | 17519193 |
| a high standard metabolic rate constrains juvenile growth. | the allocation of energy to various components of an individual's energy budget is often viewed as a competitive process. as such, a tradeoff may exist between production (growth) and maintenance metabolism. one view of a potential tradeoff, termed "the principle of allocation", suggests that individuals with lower maintenance metabolic expenditures may have higher growth rates. to determine whether such a tradeoff exists, i analyzed the relationship between growth rate and maintenance metabolis ... | 2002 | 16351863 |