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observations on haemogregarina balli sp. n. from the common snapping turtle, chelydra serpentina.haemogregarina balli sp. n. is described from the blood and organs of the common snapping turtle chelydra serpentina serpentina and from the gastric and intestinal ceca of the presumed invertebrate hosts, the leeches placobdella parasitica and placobdella ornata. in the peripheral blood of the turtle, male and female gametocytes and immature erythrocytic schizonts are found within erythrocytes. the maturation of erythrocytic schizonts containing 6-8 merozoites is recorded from liver imprints. sc ...1976819649
somatotropic effects of prolactin and growth hormone in juvenile snapping turtles (chelydra serpentina). 19734753356
tissue culture analysis of immunological capacity of snapping turtles. 19684877627
responses of single rods in the retina of the turtle.1. the responses of rods in the retina of the turtle, chelydra serpentina, have been studied by intracellular recording.2. the identification of rods as the origin of the recorded responses has been confirmed by marking with procion yellow.3. the response to a small spot of light was a hyperpolarization which increased with increasing light intensity. for dim, small diameter stimuli, the shape of the rod response was similar to that of cones but 2x slower and 2x larger in amplitude. the time int ...19734759680
the development of segmentation in the cranial region of vertebrate embryos.the purpose of this review is to show how the development of metameric pattern in the mesoderm of vertebrate embryos is related to cranial segmentation. direct visual evidence is presented which shows that the segmental development of several vertebrate embryos is initiated as early as gastrulation. in the paraxial mesoderm of the head, somitomeres, identified in stereo with the sem, accumulate as tandem units. somitomeres remain contiguous in the cranial region, but separate from one another in ...19826763329
turtle lymphocyte surface antigens in chelydra serpentina as characterized by rabbit anti-turtle thymocyte sera.spleen and thymus suspensions from the turtle, chelydra serpentina were examined by indirect immunofluorescence with a rabbit anti-turtle thymocyte serum (ratt). after the species-specific antibodies had been absorbed out, the antisera labeled all lymphocytes in the thymus and spleen. the specificity of ratt for thymocytes was greater than the specificity for splenic lymphocytes. the presence of two antigens, one thymus specific, ts, and another shared by both thymocytes and splenic lymphocytes, ...19846734872
morphogenesis of the cranial segments and distribution of neural crest in the embryos of the snapping turtle, chelydra serpentina.recent studies of the heads of vertebrates have shown a primitive pattern of segmentation in the mesoderm and neural plate not previously recognized. the role of this pattern in the subsequent distribution of cranial crest and the development of branchial arches and cranial nerves, may resolve century-old arguments about the evolution of vertebrate segmentation. in this study, we examine the early embryonic development of the cranium of a primitive amniote, the snapping turtle, with the sem. we ...19846706002
dermatophilus chelonae sp. nov., isolated from chelonids in australia.three isolates of a previously undescribed dermatophilus sp. obtained from chelonids (two strains obtained from turtles and one strain obtained from a tortoise) were compared with 30 dermatophilus congolensis isolates obtained from australian mammals. the microscopic appearance, the colony morphology, and most biochemical test results for the chelonid isolates were characteristic of the genus dermatophilus. our isolates differed from the mammalian d. congolensis isolates in a number of cultural ...19957857807
surface immunoglobulin on granular and agranular leukocytes in the thymus and spleen of the snapping turtle, chelydra serpentina.spleen and thymus suspensions from the turtle, chelydra serpentina were examined by indirect immunofluorescence and found to contain both agranulocytes and granulocytes positive for surface ig. among the splenic agranulocytes , 50% of the lymphocyte and monocyte population was positive for surface ig. in the thymus only 7% of the thymocytes were positive. ninety-two percent of the granulocytes, composed primarily of basophils and eosinophils, were positive for surface ig in both the thymus and s ...19846373420
an analysis of transmission from cones to hyperpolarizing bipolar cells in the retina of the turtle.voltage noise was recorded from centre-hyperpolarizing bipolar cells in the retina of the snapping turtle. the identity of the cells was confirmed by intracellular staining. the variance of the voltage fluctuations of the membrane potential present in the dark was suppressed by up to 30-fold by 100 microns diameter light spot stimuli centred on the cell's receptive field. such noise reduction is expected when light hyperpolarizes the photoreceptors and reduces the rate of release of transmitter ...19836310101
anti-immunoglobulin induced histamine release from naturally abundant basophils in the snapping turtle, chelydra serpentina.the dose response, temperature sensitivity, time course and calcium dependency of histamine release from snapping turtle basophils treated with rabbit anti-turtle immunoglobulin (ratig) sera was explored. this investigation indicated that the level of histamine release induced by ratig was dependent upon the concentration of ratig with concentrations of 350 mcg/ml inducing optimal release. in addition, release was temperature dependent with release increasing over a temperature range of 10 degre ...19846203781
purification and properties of alligator mississipiensis cytochrome c.cytochrome c has been purified to homogeneity from alligator liver (alligator mississipiensis) using aluminum sulfate precipitation, cm-cellulose and gel-filtration chromatography, and reverse-phase hplc. the protein exhibited a single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis with an approximate molecular weight of 12,000 da. oxidized and reduced visible spectra yielded maxima at 408 (tau) nm and 315 (delta), 415 (tau), 520 (beta), and 550 (alpha) nm, respectively, while ...19938384830
naturally abundant basophils in the snapping turtle, chelydra serpentina, possess cytophilic surface antibody with reaginic function.basophils constitute 50 to 63% of the blood leukocytes in chelydra serpentina, the snapping turtle. immunoglobulin (ig) on the surface of the turtle basophil was detected by indirect immunofluorescence by using an igg fraction from rabbit anti-turtle ig serum (ratig) and a fluoresceinated goat anti-rabbit antibody incubated at 4 degrees c. however, when the cells were incubated with ratig at 22 degrees c, the basophil number, as determined by wright's stain and neutral red counts, decreased dram ...19836183356
somite formation in cultured embryos of the snapping turtle. chelydra serpentina.a simple, reliable method for the in vitro cultivation of snapping turtle embryos was demonstrated. this technique was used to study somite formation in explants containing segmental plates. segmental plates formed a full complement of somites whether the neural tube or the neural tube and notochord was present. explanted snapping turtle segmental plates formed an average of 6.6 +/- 1.2 somites. removal of the node region or tail bud from cultured intact embryos led to a cessation of somite form ...19807217866
the absence of spread of adaptation between rod photoreceptors in turtle retina.adaptation by weak backgrounds and the spatial spread of desensitization between rods was studied in the snapping turtle retina, chelydra serpentina. intracellular membrane potentials were recorded from these photoreceptors in an eyecup preparation. the kinetics and sensitivity of rod responses were changed significantly by large, very dim backgrounds. for the twenty-five most sensitive rods where the dark-adapted flash sensitivity, sdf, was greater than 1.0 mv/rh*, rh* being the number of effec ...19854093878
the amino acid sequence of snapping turtle (chelydra serpentina) ribonuclease.snapping turtle (chelydra serpentina) ribonuclease was isolated from pancreatic tissue. turtle ribonuclease binds much more weakly to the affinity chromatography matrix used than mammalian ribonucleases. the amino acid sequence was determined from overlapping peptides obtained from three different digests. the n-terminal amino acid sequence of the protein determined by others [e. a. barnard, m. s. cohen, m. h. gold j.-k. kim (1972) nature (lond.) 240, 395-398] and homology were used as additiona ...19854076178
nonmammalian growth hormones have diabetogenic and insulin-like activities.purified ghs isolated from ostrich, sea turtle, snapping turtle, bullfrog, tilapia, and sturgeon were tested for in vivo diabetogenic activity in the hereditarily obese ob/ob mouse and for in vitro insulin-like activity in isolated adipose tissue from hypophysectomized rats. ghs from all species exhibited significant diabetogenic activity, causing fasting hyperglycemia and decreased glucose tolerance when administered at doses of 100 micrograms/day (ostrich, bullfrog, and sturgeon) or 200 microg ...19853882411
the regulation of tyrosinase gene transcription.tyrosinase is one of the key enzymes essential for melanogenesis. the control of its activity rests in part at the level of transcriptional regulation. the 5' promoter regions of the human, mouse, chicken, quail, snapping turtle, and frog tyrosinase sequences have been isolated and the mechanisms regulating the activity of these sequences are beginning to be elucidated. this review provides an update on the following aspects of tyrosinase gene regulation: basal promoter elements that determine t ...19979266599
somitomeres: mesodermal segments of vertebrate embryos.well before the somites form, the paraxial mesoderm of vertebrate embryos is segmented into somitomeres. when newly formed, somitomeres are patterned arrays of mesenchymal cells, arranged into squat, bilaminar discs. the dorsal and ventral faces of these discs are composed of concentric rings of cells. somitomeres are formed along the length of the embryo during gastrulation, and in the segmental plate and tail bud at later stages. they form in strict cranial to caudal order. they appear in bila ...19883077109
the effects of cold acclimation on electrocardiogram parameters in five species of turtles.the effects of thermal acclimation at 25 or 5 degrees c on electrical activity in the heart were investigated in pseudemys scripta, terrapene carolina, chrysemys picta marginata, chrysemys picta dorsalis, chelydra serpentina, and sternotherus odoratus. the durations of the qrs complex and p-r, r-t and r-r intervals were found to increase with decreasing body temperature in all animals tested. the amplitudes of the p and t waves and qrs complex were dependent upon both acclimation temperature and ...19872886260
temperature dependence of in vitro pituitary, testis, and thyroid secretion in a turtle, pseudemys scripta.in vitro culture was used to examine the direct actions of temperature at the level of pituitary hormone [luteinizing hormone (lh), thyrotropin (tsh), growth hormone (gh), prolactin (prl)] responses to neuropeptides and two related peripheral endocrine responses [thyroid hormone (t4) and testicular androgen secretion] to pituitary hormones (tsh and gonadotropins) in a turtle, pseudemys scripta. all these responses were fully suppressed at very low temperatures (5-6 degrees) and maximal near the ...19892512196
phylogeny of regulatory regions of vertebrate tyrosinase genes.highly homologous dna elements were found to be shared by the upstream regions of the mouse tyrosinase and tyrosinase related protein (trp-1) genes. several nuclear proteins were shown to bind to both of these upstream regions. shared homologous dna elements were also found in the 5' flanking sequences of japanese quail and snapping turtle tyrosinase genes. shared homologous nucleotide sequences were found to be scattered like an archipelago in the 5' upstream regions of mouse and human tyrosina ...19921292011
isolation and characterization of follicle-stimulating hormone and luteinizing hormone and its subunits from snapping turtle (chelydra serpentina) pituitaries.highly purified luteinizing hormone and follicle-stimulating hormone have been isolated from extracts of snapping turtle (chelydra serpentina) pituitaries. both hormones are potent in non-mammalian gonadotropin bioassays (1.8 x nih-lh-s1 and 30 x nih-fsh-s1). the materials have been characterized by polyacrylamide gel electrophoresis, amino terminal group analysis, amino acid and carbohydrate content, and, in the case of turtle luteinizing hormone, ultracentrifugation. the luteinizing hormone wa ...19761261497
cones excite rods in the retina of the turtle.the intracellular responses of rods in the retina of the turtle, chelydra serpentina, were studied with brief flashes of monochromatic light. 1. flashes of red or green light applied over an area 25 mum in diameter produce responses with the same shape. with such restricted stimuli, the spectral sensitivity of a rod agrees well with the absorption spectrum of the porphyropsin pigment contained in its outer segment. 2. with stimulating spots more than 500 mum in diameter, dim flashes of red or gr ...19751133790
rod-rod interaction in the retina of the turtle.intracellular responses were recorded from rods in isolated eye-cups of the snapping turtle, chelydra serpentina. responses to small and large diameter spots of 500 nm light were studied. 1. the peak amplitudes of responses smaller than approximately 2 mv were directly proportional to irradiance. small spots (less than 100 mum diameter) produced approximately 30 muv/rhodopsin molecule bleached. increasing stimulus diameter to 400-500 mum increased this five to seven times to about 200 muv/rhodop ...19751133789
antileptospiral activity in lower-vertebrate sera.normal serum from the painted turtle (chrysemys picta), the snapping turtle (chelydra serpentina), and the frog (rana pipiens) were found to possess bactericidal activity towards leptospira. leptospires from both the parasitic and biflexa complexes were killed by these sera at high dilutions. this pattern differs from that of mammalian serum, as generally only the biflexa complex leptospires are killed by normal mammalian serum. the activity in c. picta serum was characterized as being complemen ...19751081972
pituitary growth hormones: further evidence for evolutionary conservatism based on immunochemical studies.immunochemical relatedness of preparations of purified somatotropins (growth hormones) of somatotropins in pituitary extracts from various vertebrate species was investigated by applying an antiserum to a purified somatotropin from a submammalian species, the snapping turtle. with the exception of monkey somatotropin, all mammalian, reptilian, and avian preparations tested showed reactions of identity or near identity by immunodiffusion studies in agar gel. radioimmunoassay employing labeled rat ...19751060111
electrical properties of the rod syncytium in the retina of the turtle.1. intracellular responses were recorded from rods in isolated eye-cups of the snapping turtle. chelydra serpentina. responses to flashes of small (less than 100 mum diameter) and large (1000 mum diameter) spots of 500 nm light were studied. 2. responses produced by small and large diameter spots which delivered less than 0-3 photons mum-2 had the same shape. the responses produced by large spots were, however, nearly ten times greater in amplitude. the difference in amplitude is termed enhancem ...1976950599
purification and properties of reptilian and amphibian growth hormones.highly purified growth hormone was isolated from the pituitaries of two reptilian species, the snapping turtle and the sea turtle, and two amphibian species, the bullfrog and the leopard frog. characterization studies were performed with these growth hormones in comparison with mammalian and avian growth hormones. great similarities among these species were found in chromatographic behavior, ve/vo ratios (2.0) on gel filtration, disc electrophoretic patterns, terminal amino acid residues and imm ...1976821743
molecular mechanisms of tsd in reptiles: a search for the magic bullet.significant progress has been made in understanding mechanisms of genetic sex determination. the zfy gene encodes a zinc finger protein but is not the primary signal in sex determination. the sry gene is the testis determining gene in man, mouse, rabbit, and probably marsupial mouse and wallaby. temperature dependent sex determination probably involves a modification of development of the indifferent gonad due to differential expression of one or more specific dna sequences whose behavior is con ...19947931129
binding affinities of thyroxine-binding proteins in turtle plasma.binding affinities (ka) for thyroxine (t4) by blood plasma and purified plasma proteins from two turtles, the slider (trachemys scripta) and snapper (chelydra serpentina), were compared with those of a human using equilibrium dialysis. the purified t4 binding protein (tbp) from t. scripta had a high affinity that was lower by about fivefold than that of human tbg (3.2 x 10(9) vs 1.7 x 10(10) m-1). the affinity of t4 binding by tbp was similar to that determined for whole plasma from this species ...19938504925
comparison of the structure of turtle pancreatic ribonuclease with those of mammalian ribonucleases.there are 33 invariant amino acid positions out of 132 positions in 42 investigated sequences of ribonucleases from a number of mammalian species and a reptile (snapping turtle, chelydra serpentina). these invariant residues are unequally distributed over 3 different parts of the molecule. the lobe of the s-protein part of the molecule, which lacks one disulfide bridge and has two shortened loops in turtle ribonuclease, has the lowest percentage of invariant residues, although the active-site re ...19863940901
cytoplasmic progesterone receptors in uterine tissue of the snapping turtle (chelydra serpentina).a high affinity progesterone-binding component was detected in the cytosol of the uterus of the snapping turtle, chelydra serpentina. density gradient centrifugation indicated that binding of [3h]progesterone and [3h]promegestone (r5020) was to a fraction with a heavier sedimentation coefficient than bovine serum albumin (bsa) appearing as a broader peak in the 6-7 s region; it was not affected by excess cortisol. another binding peak, lighter than bsa and appearing with [3h]r5020 and [3h]proges ...19863734671
brain peptide yy receptors: highly conserved characteristics throughout vertebrate evolution.we have shown previously that peptide yy (pyy) receptors are uniquely distributed in various mammalian brains and also have identified the receptor from porcine hippocampal membranes as a protein of 50,000 mol wt. to extend these observations, both the characteristics of pyy-receptor interaction and the structure of the receptor have been examined and compared with those of its sister peptide, neuropeptide y (npy), in the brains of various vertebrates including mammals (human, dog, guinea pig, r ...19911657579
temporal and spatial characteristics of the voltage response of rods in the retina of the snapping turtle.1. in response to strong, large-field flashes the dark-adapted rods of chelydra serpentina gave initial hyperpolarizing responses of 30-40 mv, declining rapidly to plateaus of 10-15 mv which lasted 20 sec or more.2. in the most sensitive cells the flash-sensitivity at 520 nm to a large illuminated area was 3-6 mv per photoisomerization (assuming an effective collecting area of 13.6 mum(2)).3. the initial response to a step of light agreed with that predicted by super-position from the flash resp ...19807381784
sequence analysis of the zfy and sox genes in the turtle, chelydra serpentina.we have sequenced regions of the zfy and sox genes in the turtle chelydra serpentina, a reptile with temperature-dependent sex determination. the zfy gene in mammals encodes a transcription factor with multiple zinc fingers that may be involved in spermatogenesis as well as other processes. the turtle homologue, zft, is 92% identical to the zfy gene at the nucleotide and amino acid levels in the region of zinc fingers 7-12. there are several sox genes in the turtle that are only 57-70% identical ...19948025725
environmental occurrence and potential toxicity of planar, mono-, and di-ortho polychlorinated biphenyls in the biota.four non-ortho-, eight mono-ortho-, and two di-ortho-chlorinated congeners have been determined in fresh water and salt water mussels, fish, snapping turtles, mallard, seals, and in human milk and adipose tissue. the planar pcb congeners are separated from the remainder of pcbs by activated carbon chromatography or hplc on porous graphitic carbon followed by gas chromatography with electron capture detection. pcb toxic equivalency factors (tefs) recommended by who [1] for 3 non-ortho, 8 mono-ort ...19989503581
development of the pulmonary surfactant system in non-mammalian amniotes.pulmonary surfactant (ps) is a complex mixture of phospholipids, neutral lipids and proteins that lines the inner surface of the lung. here, it modulates surface tension thereby increasing lung compliance and preventing the transudation of fluid. in mammals, the ps system develops towards the end of gestation, characterized by an increase in the saturation of phospholipids in lung washings and the appearance of surfactant proteins in amniotic fluid. birth, the transition from in utero to the ext ...200111369533
characteristics of growth hormone isolated from sturgeon (acipenser güldenstädti) pituitaries.gh was isolated and characterized from pituitaries of a primitive bony fish, sturgeon (acipenser güldenstädti). sturgeon gh was very active in a mammalian gh assay, the rat tibia test. relative to ovine gh (nih-gh-s9), sturgeon gh gave a parallel dose-response slope and had a potency of 0.4. sturgeon gh also showed strong cross-reaction in a snapping turtle gh ria, comparable to that shown by tetrapod ghs and much greater than that of modern bony fish (teleost) gh. these results, predicted by ea ...19817449727
comparative studies of thyroxine binding proteins in turtle plasma using column chromatography.thyroxine (t4) binding proteins in turtle plasma were compared with those of various mammalian and nonmammalian (fish, birds) species using gel filtration chromatography (bio-gel). high-affinity t4 binding was observed in all mammals studied, in the chicken, and in one species of turtle, trachemys scripta. this high affinity t4 binding protein (tbp) appears to be the major component of t4 transport in the turtle; selective removal of this tbp greatly diminished binding activity in t. scripta pla ...19938428644
lead poisoning and intestinal perforations in a snapping turtle (chelydra serpentina) due to fishing gear ingestion.an adult male snapping turtle (chelydra serpentina) was presented to the tufts wildlife clinic with generalized weakness and limited ability to walk. a fishing hook was lodged in the corner of its mouth, monofilament line trailed from its cloaca, and radiography revealed that the turtle had ingested two additional hooks and a large sinker. the hemogram showed leukocytosis. at exploratory celiotomy, the fishing line was seen to have acted as a linear foreign body and had perforated the intestines ...19979226626
sizing bands on autoradiograms: a study of precision for scoring dna fingerprints.we replicated dna fingerprints of snapping turtles (chelydra serpentina) and hypervariable restriction fragments of red-winged blackbirds (agelaius phoeniceus) to estimate the between-blot and between-lane components of variance in molecular weights of restriction fragments. molecular weight standards were included in every lane, and bands were sized using a sonic digitizer. in both studies, a strong positive correlation was found between band size and coefficient of variation (cv; mean = 0.7%). ...20061674911
characterization of a ribonuclease gene and encoded protein from the reptile, iguana iguana.in this work we identify an intronless open reading frame encoding an rnase a ribonuclease from genomic dna from the iguana iguana igh2 cell line. the iguana rnase is expressed primarily in pancreas, and represents the majority of the specific enzymatic activity in this tissue. the encoded sequence shares many features with its better-known mammalian counterparts including the crucial his12, lys40 and his114 catalytic residues and efficient hydrolytic activity against yeast trna substrate (k(cat ...200515893436
comparative patterns of postcranial ontogeny in therian mammals: an analysis of relative timing of ossification events.data on the relative sequence of ossification of postcranial elements for eight therian mammals (myotis lucifugus, homo sapiens, rattus norvegicus, mus musculus, mesocricetus auratus, cavia porcellus, didelphis albiventris, and sminthopsis macroura) and three outgroups (chelydra serpentina, alligator mississippiensis, and lacerta vivipara) were taken from the literature. for each species, a matrix was constructed in which the relative timing of the onset of ossification in 24 elements was summar ...200212362432
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
osteology and skeletal development of apalone spinifera (reptilia: testudines: trionychidae).despite considerable attention that other groups of reptiles have received, few descriptions of the development and sequences of chondrification and ossification of the entire skeleton of turtles exist. herein, the adult skeleton of the spiny softshell turtle, apalone spinifera (testudines: trionychidae), is described; this description forms a basis of comparison for the embryonic skeleton and its ontogenesis. descriptions are made on the basis of cleared and double-stained embryos and dry skele ...200312616574
absence of detectable salmonella cloacal shedding in free-living reptiles on admission to the wildlife center of virginia.salmonellosis is an important reptile-associated zoonotic infection in the united states. cloacal swabs were collected from reptiles admitted to the wildlife center of virginia, waynesboro, virginia, cultured for salmonella using hektoen and xylose lysine deoxycholate agars, and inoculated in selenite broth. all three were incubated at 37 degrees c for 18-24 hr. seventy-five animals were included in the study, representing eight species, 34 eastern box turtles (terrapene carolina carolina), 14 e ...200415732603
the amino acid sequence of iguana (iguana iguana) pancreatic ribonuclease.the pyrimidine-specific ribonuclease superfamily constitutes a group of homologous proteins so far found only in higher vertebrates. four separate families are found in mammals, which have resulted from gene duplications in mammalian ancestors. to learn more about the evolutionary history of this superfamily, the primary structure and other characteristics of the pancreatic enzyme from iguana (iguana iguana), a herbivorous lizard species belonging to the reptiles, have been determined. the polyp ...19948307028
water-vapor conductance of testudinian and crocodilian eggs (class reptilia).flexible-shelled eggs of snapping turtles (chelydra serpentina) have conductances to water vapor that are 55 times higher than predicted for avian eggs of similar size, whereas rigid-shelled eggs of softshell turtles (trionyx spiniferus) and american alligators (alligator mississippiensis) have conductances that are only five times higher than expected for comparable eggs of birds. the differences between empirical and predicted values result from the much higher effective pore areas in reptilia ...1979515558
comparative effects of diverse vertebrate gonadotropins on estradiol-17 beta formation in vitro in an immature rat sertoli cell bioassay.the biopotencies of pituitary gonadotropins (gths) from various vertebrate classes were examined in an in vitro rat sertoli cell bioassay which was previously established for mammalian follicle-stimulating hormones (fshs). potencies of the gonadotropins were determined by incubation of sertoli cells obtained from 10-day-old rats, with increasing doses of gths, which resulted in dose-related and parallel estradiol-17 beta formation converted from added 19-hydroxy-androstenedione. in general, mamm ...19968930616
purification and characterization of plasma vitamin d binding protein from the snapping turtle, chelydra serpentina.vitamin d binding protein (dbp) was isolated from the plasma of the snapping turtle, chelydra serpentina (mixed sex adult), and compared with the previously characterized dual function binding plasma protein that binds both thyroxine (t4) and vitamin d (tstdbp) in an emydid turtle, trachemys scripta. purification of chelydra serpentina dbp (csdbp) was accomplished by ion exchange chromatography, preparative polyacrylamide gel electrophoresis, and reverse-phase high-performance liquid chromatogra ...19968954770
high-resolution analysis of salmonellae from turtles within a headwater spring ecosystem.sediments and water from the pristine headwaters of the san marcos river, texas, usa, as well as swabs from biofilms on the carapace and from the cloacae of 17 musk turtles (sternotherus odoratus) and one snapping turtle (chelydra serpentina serpentina) caught at the same site, were analysed for salmonellae by culture and molecular techniques. whereas enrichment cultures from sediment and water samples were negative for salmonellae in pcr- and in situ hybridization-based analyses, both technique ...200717250751
kinematics of aquatic and terrestrial prey capture in terrapene carolina, with implications for the evolution of feeding in cryptodire turtles.studies of aquatic prey capture in vertebrates have demonstrated remarkable convergence in kinematics between diverse vertebrate taxa. when feeding in water, most vertebrates employ large-amplitude hyoid depression to expand the oral cavity and suck in water along with the prey. in contrast, vertebrates feeding on land exhibit little or no hyoid depression. in this study we compared the kinematics of terrestrial and aquatic prey capture within one species of turtle, terrapene carolina, in order ...19989658591
chelonacarus elongatus n. gen., n. sp. (acari: cloacaridae) from the cloaca of the green turtle chelonia mydas (cheloniidae).chelonacarus elongatus n. gen., n. sp. is proposed for a cheyletoid mite (acari: prostigmata) of the family cloacaridae found in the cloacal tissue of the endangered green turtle chelonia mydas linnaeus, 1758 from the atlantic coast of the republic of panama. in females, the new genus is distinguished from other genera of turtle cloacarids by the elongate slender shape of the idiosoma, the shape and pattern of sclerotization of the dorsal shield, and the fused distal ends of apodemes ii. a combi ...19989714221
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
cross-species investigations of prenatal experience, hatching behavior, and postnatal behavioral laterality.turning biases have been reported in some mammalian species, but less is known about such biases in nonmammalians. this study investigated turning biases in domestic chicks, bobwhite and japanese quail, leopard geckos, and snapping turtles. domestic chicks (white leghorn and bantam) and bobwhite quail demonstrate strong group laterality. japanese quail chicks, snapping turtles, and leopard geckos demonstrate no significant group bias. results are discussed with regard to differences in embryonic ...200111568878
functional conservation of the promoter regions of vertebrate tyrosinase genes.tyrosinase is the key enzyme for synthesizing melanin pigments, which primarily determine mammalian skin coloration. considering the important roles of pigments in the evolution and the adaptation of vertebrates, phylogenetic changes in the coding and flanking regulatory sequences of the tyrosinase gene are particularly intriguing. we have now cloned cdna encoding tyrosinase from japanese quail and snapping turtle. these nonmammalian cdna are highly homologous to those of the mouse and human tyr ...200111764277
octylphenol (op) alters the expression of members of the amyloid protein family in the hypothalamus of the snapping turtle, chelydra serpentina serpentina.the gonadal estrogen estradiol-17beta (e(2)) is important for developing and regulating hypothalamic function and many aspects of reproduction in vertebrates. pollutants such as octylphenol (op) that mimic the actions of estrogens are therefore candidate endocrine-disrupting chemicals. we used a differential display strategy (rna-arbitrarily primed polymerase chain reaction) to isolate partial cdna sequences of neurotransmitter, developmental, and disease-related genes that may be regulated by o ...200211882478
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
redescription of dracunculus globocephalus mackin, 1927 (nematoda: dracunculidae), a parasite of the snapping turtle, chelydra serpentina.dracunculus globocephalus mackin, 1927 (nematoda: dracunculoidea) is redescribed from specimens collected from the mesentery of the snapping turtle, chelydra serpentina (l.), in louisiana, usa. the use of scanning electron microscopy, applied for the first time in this species, made it possible to study details in the structure of the cephalic end and the arrangement of male caudal papillae that are difficult to observe under the light microscope. this species markedly differs from all other spe ...200415729947
wildlife as sentinels of human health effects in the great lakes--st. lawrence basin.there is no existing formal, long-term program for gathering evidence of the incidence and severity of the health effects of toxic substances in wildlife. however, research-based studies of bald eagles, herring gulls, night herons, tree swallows, snapping turtles, mink, and beluga over the past 30 years have revealed a broad spectrum of health effects in the great lakes-st. lawrence basin including thyroid and other endocrine disorders, metabolic diseases, altered immune function, reproductive i ...200111744503
intramembranous ossification of scleral ossicles in chelydra serpentina.scleral ossicles are present in many reptiles, including turtles and birds. in both groups the sclerotic ring situated in the eye is composed of a number of imbricating scleral ossicles or plates. despite this gross morphological similarity, andrews (1996. an endochondral rather than a dermal origin for scleral ossicles in cryptodiran turtles. j. herpetol. 30, 257-260) reported that the scleral ossicles of turtles develop endochondrally unlike those in birds, which develop intramembranously afte ...200616377163
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
separation of two distinct gonadotropins from the pituitary gland of the snapping turtle (chelydra serpentina). 20134544465
yolk steroid hormones and sex determination in reptiles with tsd.in reptiles with temperature-dependent sex determination (tsd), the temperature at which the eggs are incubated determines the sex of the offspring. the molecular switch responsible for determining sex in these species has not yet been elucidated. we have examined the dynamics of yolk steroid hormones during embryonic development in the snapping turtle, chelydra serpentina, and the alligator, alligator mississippiensis, and have found that yolk estradiol (e(2)) responds differentially to incubat ...200312849957
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
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
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
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
skin allograft and xenograft rejection in the snapping turtle, chelydra serpentina. 20164893940
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
comparison and evolution of the lagena in various animal species.the structure of the vestibular organs of the teleost fish (bluegill), newts (japanese fire-belly newt), frogs (black-spotted pond frog), snapping turtles and birds (chicks) was morphologically compared, with particular attention to the lagena macula, and the differences between animal species with relation to evolution were considered. teleost fish had no striola on the lagena macula. the striola of newts were short and restricted to the central area of the macula, but those of frogs, snapping ...200111425201
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
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
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
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
morbidity and mortality of reptiles admitted to the wildlife center of virginia, 1991 to 2000.medical records from 694 reptiles admitted to the wildlife center of virginia (wcv; waynesboro, virginia, usa) from 1991 to 2000 were reviewed to determine causes of morbidity and mortality. eighteen species were represented but the majority of cases were four species; eastern box turtle (terrapene carolina) (66%), eastern painted turtle (chrysemys picta) (11%), common snapping turtle (chelydra serpentina) (10%), and rat snake (elaphe sp.) (6%). there was a significant increase in reptile cases ...200212528435
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
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
survival and physiological responses of hatchling blanding's turtles (emydoidea blandingii) to submergence in normoxic and hypoxic water under simulated winter conditions.overwintering habits of hatchling blanding's turtles (emydoidea blandingii) are unknown. to determine whether these turtles are able to survive winter in aquatic habitats, we submerged hatchlings in normoxic (155 mmhg po2) and hypoxic (6 mmhg po2) water at 4 degrees c, recording survival times and measuring changes in key physiological variables. for comparison, we simultaneously studied hatchling softshell (apalone spinifera) and snapping (chelydra serpentina) turtles, which are known to overwi ...201615887082
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
marine turtle reception of bone-conducted sound.an individual each of the marine turtles, caretta caretta and lepidochelys kempi, were stimulated with audiofrequencies delivered directly to the skull. startle responses were observed to underwater stimuli of .25 and .5 kc/s. neural responses to underwater bone-conducted (bc) sound were recorded in another aquatic form, the snapping turtle, chelydridae serpentina. the morphology of the neural response suggested the involvement of the auditory system in bc responsivity. bc hearing appears to be ...19836679547
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
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
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
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
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 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
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
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
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
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
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
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
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
snapping turtles (chelydra serpentina) as bioindicators in canadian areas of concern in the great lakes basin. 1. polybrominated diphenyl ethers, polychlorinated biphenyls, and organochlorine pesticides in eggs.we examined the concentrations and spatial patterns of congeners of pbdes, pcbs, and organochlorine pesticides in snapping turtle (chelydra serpentina) eggs from areas of concern (aocs) on the canadian shores of lake ontario, st. lawrence river, and connecting channels. eggs from lyons creek (niagara river aoc) reflected a local pcb source over a range of 7.5 km (3.2-10.8) from the welland canal. pcb contamination in eggs declined with increasing distance from the welland canal, whereas the rela ...200718044496
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
toxicity of nitrogenous fertilizers to eggs of snapping turtles (chelydra serpentina) in field and laboratory exposures.many reptiles oviposit in soil of agricultural landscapes. we evaluated the toxicity of two commonly used nitrogenous fertilizers, urea and ammonium nitrate, on the survivorship of exposed snapping turtle (chelydra serpentina) eggs. eggs were incubated in a community garden plot in which urea was applied to the soil at realistic rates of up to 200 kg/ha in 2004, and ammonium nitrate was applied at rates of up to 2,000 kg/ha in 2005. otherwise, the eggs were unmanipulated and were subject to ambi ...200717702542
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
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
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