RAPD markers system as a useful tool for rapid identification of the origin of lizard contaminants in food

In food poisoning, detection of the nature of causative agent is important for management of trauma and forensic investigation. Most of the methods in clinical toxicology are developed for detection of toxins and poisons. A RAPD-based method has been described for detection of species of animal from its morphologically unrecognizable fragments, recovered from food substances, consumption of which caused even death. Pre-mixed RAPD reaction beads and six RAPD primers were used in PCR analysis. Among six RAPD primers used, any one of them was sufficient in resolving this practical forensic situation. But to enhance the probability values for matching in the present study of fixing identity of an animal, six set of market available RAPD primers were used. This is the first report of a forensic application of RAPD DNA typing in identification of charred skeleton remnants of Lizard sp. in food material. Furthermore unique amplicons were generated for different reptilian species, which can be used as species specific markers for species identification in forensic situation, however no variations among individuals of same species were observed.

Msx genes are expressed in the carapacial ridge of turtle shell: a study of the European pond turtle, Emys orbicularis

The turtle shell forms by extensive ossification of dermis ventrally and dorsally. The carapacial ridge (CR) controls early dorsal shell formation and is thought to play a similar role in shell growth as the apical ectodermal ridge during limb development. However, the molecular mechanisms underlying carapace development are still unknown. Msx genes are involved in the development of limb mesenchyme and of various skeletal structures. In particular, precocious Msx expression is recorded in skeletal precursors that develop close to the ectoderm, such as vertebral spinous processes or skull. Here, we have studied the embryonic expression of Msx genes in the European pond turtle, Emys orbicularis. The overall Msx expression in head, limb, and trunk is similar to what is observed in other vertebrates. We have focused on the CR area and pre-skeletal shell condensations. The CR expresses Msx genes transiently, in a pattern similar to that of fgf10. In the future carapace domain, the dermis located dorsal to the spinal cord expresses Msx genes, as in other vertebrates, but we did not see expansion of this expression in the dermis located more laterally, on top of the dermomyotomes. In the ventral plastron, although the dermal osseous condensations form in the embryonic Msx-positive somatopleura, we did not observe enhanced Msx expression around these elements. These observations may indicate that common mechanisms participate in limb bud and CR early development, but that pre-differentiation steps differ between shell and other skeletal structures and involve other gene activities than that of Msx genes.

IMP-GMP 5'-nucleotidase in reptiles: occurrence in a turtle, a tortoise and three species of snakes

IMP-hydrolyzing activity, which is reactive with goose anti-pig lung IMP-GMP 5'-nucleotidase (c-N-II: EC.3.1.3.5) serum, was detected in extracts from liver, heart, kidney, spleen, stomach, skeletal muscle and lung from several species of reptiles: The values found in liver (U/mg protein) of one animal were: 4.5 for an ammono-ureotelic turtle (Trionyx sinensis japonicus); 3.7 for an ureo-uricotelic tortoise (Testudo elegans); 13-23 for three species of uricotelic snakes: Elaphe quadrivirgata, Elaphe conspicillata and Elaphe climacophora. These findings suggest that in the liver of snakes, c-N-II may participate in the production of uric acid as an end product of amino acid metabolism.

Abducens conditioning in in vitro turtle brain stem without cerebellum requires NMDA receptors and involves upregulation of GluR4-containing AMPA receptors

Previous work showed that in vitro abducens eyeblink classical conditioning of turtle brain stem-cerebellum preparations involved NMDA-mediated mechanisms and redistribution of GluR4-containing AMPA receptors in the abducens motor nuclei. Since conditioning can be obtained in brain stem preparations without the cerebellum, we examined whether similar mechanisms were involved during conditioning of the brain stem alone. The results showed that conditioning could not be induced in the presence of the NMDA receptor antagonist dl-2-amino-5-phosphonovaleric acid (AP-5) and that abducens nerve conditioned responses, once initiated in normal saline, were significantly attenuated in the presence of AP-5. The effects of AP-5 did not generally depress physiological responsiveness of preparations because some abducens nerve reflexes were not significantly reduced by the compound. GluR4-containing AMPA receptors in the abducens motor nuclei were significantly upregulated and positively correlated with the levels of conditioning similar to that of preparations having an intact cerebellum. Furthermore, increased GluR4 subunits after brain stem conditioning was confirmed by Western blot analysis. These results suggest that NMDA receptor-mediated mechanisms and GluR4 upregulation may mediate in vitro abducens eyeblink classical conditioning and that these mechanisms reside in the brain stem eyeblink circuitry.

Occurrence of several arsenic compounds in the liver of birds, cetaceans, pinnipeds, and sea turtles

Concentrations of total arsenic and individual arsenic compounds were determined in livers of birds, cetaceans, pinnipeds, and sea turtles by using hydride generation-atomic absorption spectrometry and high-performance liquid chromatography/inductively coupled plasma-mass spectrometry. Hepatic arsenic concentrations in loggerhead turtles (11.2 +/- 3.0 microg/g dry wt) and black-footed albatrosses (12.2 +/- 10.8 microg/g dry wt) were extremely high among the species examined, and the values were comparable with those of lower trophic marine animals such as fishes, cephalopods, crustaceans, and shellfishes. In all the species, arsenobetaine was the predominant arsenic compound in the livers. Especially, for black-footed albatrosses and black-tailed gull, the mean percentage of arsenobetaine was as high as 97.1 and 87.5, respectively, of extractable arsenic. The present study is among the first on arsenic speciation in avian species. Total arsenic concentration was strongly correlated with the concentration of arsenobetaine, while no significant relationship was observed between total arsenic concentration and other arsenic compounds in these animals. Because arsenobetaine is known to be rapidly excreted into the urine in humans and experimental animals, the observed results suggest that higher trophic marine animals might have a unique metabolism of arsenobetaine and that arsenobetaine plays an important role in the accumulation of arsenic in these animals.

Characterization of lipoproteins from the turtle, Trachemys scripta elegans, in fasted and fed states

The lipid and apolipoprotein composition of VLDL, IDL, LDL, HDL(2) and HDL(3) were examined in the turtle, Trachemys scripta elegans, in fasted and fed states. The lipid composition of turtle lipoproteins was very similar to their human counterparts. The major apolipoprotein found in LDL, IDL and VLDL, which has a molecular weight of approximately 550 kD, is a homologue of apoB100. The major apolipoprotein found in both HDL(2) and HDL(3), has a molecular weight of 28-kD and is homologous to human apoA-I. HDL(3) also contains a 6.5 kD protein that is homologous to apoA-II, while HDL(2) has two low molecular weight proteins of 6 kD and 7 kD which are also found on the triglyceride rich lipoproteins (TRL). The 7 kD protein is homologous to apoC-III, while the 6 kD protein has a similar size and distribution as apoC-II or apoC-I. In addition, HDL(2) also possesses a protein of 15.8 kD that has no obvious mammalian homologue. In both size and apolipoprotein composition, turtle HDL(2) resembles human HDL(2b) while turtle HDL(3) resembles human HDL(3). In the fasted state, turtles contained very little TRL. When fed a high fat diet, the amount of IDL and LDL sized particles increased significantly.

Lipids and lipid-transporting proteins in Chrysemys picta: role of gonadal steroids and growth hormone in intact and hypophysectomized turtles

In the freshwater turtle, the homeostatic control of plasma lipids and lipid-transporting proteins may be coordinately regulated by ovarian steroids and pituitary hormones such as growth hormone (GH). In order to elucidate the role of these hormones in the regulation of vitellogenesis and ovarian growth, we have investigated lipid metabolic changes in normal male and female turtles, and in hypophysectomized females with and without GH injections, in response to combinations of exogenously administered gonadal steroids (estradiol (E2), progesterone (P), and testosterone (T)). Determinations of total plasma triglycerides, cholesterol, vitellogenin, and apoA-I were performed. We have demonstrated that E2 alone and in combination with P significantly increased plasma apoA-I and triglyceride levels in both intact female and male turtles. Testosterone administered alone to males had no effect on any of the parameters measured. In hypophysectomized females, plasma apoA-I, vitellogenin, and triglyceride levels were all significantly elevated in animals which received GH and E2, compared to controls (sham and hypox) and those which received GH alone.

Colocalization of WT1 and cell proliferation reveals conserved mechanisms in temperature-dependent sex determination

During vertebrate development the gonad has two possible fates, the testis or the ovary. The choice between these fates is made by a variety of sex-determining mechanisms, from the sex-determining gene on the Y chromosome (Sry) in mammals, to nongenetic temperature-dependent systems in many reptiles. Despite the differences in the mechanisms at the top of the sex-determining cascade, the resulting morphology and many genes involved in early testis and ovarian development are common to most vertebrates, leading to the hypothesis that the underlying processes of sex determination are conserved. In this study, we examined the early steps of gonad development in the red-eared slider turtle (Trachemys scripta), a species that uses the temperature of egg incubation to determine sex. A dramatic increase in cell proliferation was observed in the male gonad during the earliest stages of sex determination. Using the localization of Wilms' Tumor suppressor 1 (WT1), we determined that this proliferation increase occurred in a population that contained pre-Sertoli cells. The proliferation of pre-Sertoli cells has been documented during sex determination in both mice and alligators, suggesting that proliferation of this cell type has an important role in vertebrate testis organogenesis and the determination of male fate.

Pharmacokinetics of florfenicol in loggerhead sea turtles (Caretta caretta) after single intravenous and intramuscular injections

The pharmocodynamics of single injections of florfenicol in yearling loggerhead sea turtles (Caretta caretta) were determined. Eight juvenile loggerhead sea turtles weighing 1.25 (+/- 0.18) kg were divided into two groups. Four animals received 30 mg/kg of florfenicol i.v., and four received the same dose i.m. Plasma florfenicol concentrations were analyzed by reverse-phase high performance liquid chromatography. After the i.v. dose, there was a biphasic decline in plasma florfenicol concentration. The initial steep phase from 3 min to 1 hr had a half-life of 3 min, and there was a longer slow phase of elimination, with a half-life that ranged from 2 to 7.8 hr among turtles. The volume of distribution varied greatly and ranged from 10.46 to -60 L/kg. Clearance after the i.v. dose was 3.6-6.3 L/kg/hr. After the i.m. injection, there was a peak within 30 min of 1.4-5.6 microg/ml, and florfenicol was thereafter eliminated with a half-life of 3.2-4.3 hr. With either route, florfenicol plasma concentrations were below the minimum inhibitory concentrations for sensitive bacteria within 1 hr. Florfenicol does not appear to be a practical antibiotic in sea turtles when administered at these doses.

Seasonal variation in plasma catecholamines and adipose tissue lipolysis in adult female green sea turtles (Chelonia mydas)

We investigated three aspects of potential interrenal regulation of reproduction in female green sea turtles, Chelonia mydas. First, seasonal trends in plasma catecholamines were examined from female C. mydas at different stages of their reproductive cycles. Second, variation in catecholamine levels during a nesting season were analysed in relation to restraint time, and ecological variables such as nesting habitat, body size, and reproductive investment. Third, catecholamine and corticosterone (CORT) induced lipolysis was investigated with adipose tissue collected from gravid green turtles, using in vitro incubations. Plasma epinephrine (EPI) was lowest in non-vitellogenic (1.55 +/- 0.26 ng/ml) and post-breeding (1.57 +/- 0.22 ng/ml) females, and highest in courting females (2.87 +/- 0.28). Concentrations of norepinephrine (NE) and EPI were relatively constant throughout a nesting season, and not significantly related to restraint time, reproductive investment or nesting habitat. In vitro concentrations of CORT (>3 ng/ml) and NE (2 ng/ml) induced significant release of glycerol after 6h of incubation. Epinephrine tended to induce an antilipolytic affect at low concentrations (0.25 ng/ml) and a net lipolytic response at higher concentrations (>1 ng/ml). Our data suggest that EPI may play a role in regulating body condition during vitellogenesis, and maintaining energy stores during prolonged aphagia during courtship and nesting in female green sea turtles. Furthermore, we provide preliminary evidence that suggests that catecholamine production may be either down regulated or de-sensitised in gravid female C. mydas.

Purification and properties of ornithine carbamoyltransferase from loggerhead turtle liver

Ornithine carbamoyltransferase has been purified from the liver of the loggerhead turtle Caretta caretta by a single-step procedure using chromatography on an affinity column to which the transition-state analogue, delta-N-(phosphonoacetyl)-L-ornithine (delta-PALO), was covalently bound. The procedure employed yielded an enzyme which was purified 373-fold and was judged to be homogeneous by nondenaturing and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The enzyme showed a specific activity of 224. The molar mass of the C. caretta enzyme was approximately 112 kDa, the single band obtained by SDS-PAGE indicated a subunit molar mass of 39.5 kDa; hence, the enzyme is a trimer of identical subunits. It catalyzes an ordered sequential mechanism in which carbamoyl phosphate binds first, followed by L-ornithine. The Michaelis constants were 0.858 mM for L-ornithine and 0.22 mM for carbamoyl phosphate, the dissociation constant of the enzyme-carbamoyl phosphate complex was 0.50 mM.

Effect of gonadal steroids on progesterone receptor, estrogen receptor, and vitellogenin expression in male turtles (Chrysemys picta)

Hepatic vitellogenin (vtg) is a yolk precursor protein sequestered in follicular oocytes as nutrient supply for developing embryos in nonmammalian vertebrates. In prior research studies we have demonstrated that both progesterone (P) and testosterone (T) inhibit estrogen (E)-induced vitellogenesis in the male fresh water turtle (Chrysemys picta), and have suggested that these hormones may be involved in multihormonal regulation of vitellogenesis in the female turtle. However, the modes of action of progesterone and testosterone on estrogen-induced vitellogenesis are not known. We have proposed that progesterone inhibits vitellogenesis by modulation of progesterone receptor A (PRA) or B (PRB) isoforms and/or estrogen receptor (ER) gene transcription. In this study, we compare the vitellogenic responses of reproductively inactive male turtles to estradiol 17beta in the presence of exogenous testosterone or progesterone. Northern blot analysis was used to monitor the changes in vtg mRNA, ER mRNA, and PR mRNA expression; Western blotting to determine changes in PR isoform expression and a homologous ELISA for measurement of plasma vtg. Progesterone and testosterone reduced estrogen-induced vtg mRNA expression, but plasma vtg was not significantly reduced by these steroids. PRA and PRB were transcribed even though ER mRNA could not be detected, suggesting constitutive PR expression. However, in the presence of estradiol 17beta, both PR isoforms and mRNA transcripts were increased as a correlate of ER mRNA transcription, suggesting both transcriptional and translational effects; these effects were inhibited by testosterone and progesterone treatments. Since ER mRNA was sharply reduced by both testosterone and progesterone, and estradiol 17 beta increased PR mRNA transcription and translation, it is likely that the action of progesterone in reducing vtg mRNA is indirect via down regulation of ER mRNA, thus ER. This study provides further information on the role of progesterone and testosterone in the regulation of hepatic vitellogenesis, suggesting regulation of vitellogenesis mainly via modulation of hepatic ER mRNA.

Tissue-specific expression of inducible and constitutive Hsp70 isoforms in the western painted turtle

Expression of Hsp73 and Hsp72 in four tissues of the naturally anoxia-tolerant western painted turtle (Chrysemys picta) was investigated in response to a 24 h forced dive and following 1 h recovery. Of the tissues examined, brain and liver displayed approximately threefold and sevenfold higher basal Hsp73 expression than heart and skeletal muscle. Basal Hsp72 expression was relatively low in all tissues examined. After the 24 h forced dive and 1 h recovery, Hsp73 expression did not differ significantly from basal expression with the exception of liver, where expression decreased significantly after 1 h recovery. Hsp72 expression was unchanged in liver following a 24 h dive; however, it increased twofold in brain and threefold in heart and skeletal muscle. Dive-induced Hsp72 expression was found to correlate inversely with basal Hsp73 expression. Following 1 h recovery, Hsp72 expression was significantly elevated in all tissues above levels in dived animals. These data indicate a tissue-specific pattern of Hsp73 and Hsp72 expression in the western painted turtle during both unstressed and stressed conditions.

Patterns of lipid storage and mobilisation in the female green sea turtle ( Chelonia mydas)

Reproductive data from southern Queensland indicate that vitellogenesis in female Chelonia mydas takes approximately 8 months and is followed by a migration to a breeding area. At Heron Island, females lay multiple clutches over approximately 3 months. To investigate how females mobilise and store lipid during the breeding season we collected plasma, yolk, and fat tissue samples from females at a variety of stages during the nesting season. In breeding females, concentrations of plasma triglyceride increased seasonally. They reached peak concentrations during vitellogenesis and courtship, remained high throughout the nesting season, and then declined to a nadir after the last clutch. Plasma protein concentration increased throughout the breeding season, peaking following the last clutch for the season. Yolk lipids were highest during courtship and were similar throughout the nesting season, suggesting that uptake of lipid by ovarian follicles is completed prior to the beginning of the nesting season. Plasma triglyceride decreases in females with prolonged periods of unsuccessful nesting, and total lipid levels in adipose tissue and follicle yolks were significantly lower in atretic females. It appears that: (1) endogenous energy reserves can be reduced by stochastic environmental events (such as those reducing nesting success), and (2) a metabolic shift signalling the end of the nesting season is characterised by a drop in plasma triglycerides and slight increase in total plasma protein.

Experimental manipulation of steroid concentrations in circulation and in egg yolks of turtles

Steroid hormones in egg yolks are increasingly recognized as an important component of maternal and offspring fitness in oviparous vertebrates. Yet, except for in birds, the mechanism by which females allocate these resources is poorly understood. We manipulated systemic levels of hormones in reproductively mature female red-eared slider turtles (Trachemys scripta elegans) with silastic implants to test the hypothesis that hormones are allocated to developing follicles as a quantitative function of circulating levels in the females. Turtles exhibited similar amounts (<1 ng/ml) of circulating steroids (dihydrotestosterone, estradiol-17 beta, or testosterone) in early September immediately prior to experimental manipulation. After treatment with silastic implants, circulating levels of steroids increased markedly. By the following April after hibernation, circulating levels of dihydrotestosterone had returned to preimplantation levels, but circulating levels of estradiol-17 beta and testosterone in estradiol-17 beta- and testosterone-treated turtles, respectively, remained substantially elevated through April. Focusing on testosterone, we detected nearly six-fold higher concentrations in yolk from mature follicles from testosterone-treated turtles than in yolk from mature follicles from control turtles. Our results provide support for the hypothesis that concentrations of steroids in egg yolks of turtles reflect circulating concentrations of steroids during follicular development rather than the hypothesis that females selectively allocate specific amounts of steroid hormones to each egg separately. Our findings also highlight an unambiguous physiological mechanism by which nongenetic maternal effects in oviparous species can directly influence the nutritional milieu experienced by developing embryos.

Maternally derived yolk hormones vary in follicles of the painted turtle, Chrysemys picta

The transfer of hormones from a female to her offspring is known to occur in egg laying vertebrates, and the potential for these early, maternally derived hormones to influence sex determination in reptiles with temperature-dependent sex determination is intriguing. In the present study, we examine variation in the concentrations of progesterone, testosterone, and estradiol among three follicle size classes within a female painted turtle (Chrysemys picta) and among females across four periods that span the pre- to post-nesting season. Females were collected, and both follicles and shelled eggs (when present) were harvested for hormone analysis. Progesterone levels did not vary seasonally. However, the concentration of progesterone did vary among and within follicle classes, and was primarily dependent upon ovulatory state: Recently ovulated follicles (as yolks within shelled eggs) contained significantly more progesterone than unovulated follicles. Concentrations of testosterone were low and did not vary either among size classes or across the season. Estradiol levels decreased with increasing follicle size and were higher later in the nesting season. Thus, hormone concentrations varied among follicle sizes and states but in patterns that differed among hormones. This variation has the potential to influence sex determination.

Mechanisms for maintaining extracellular glutamate levels in the anoxic turtle striatum

The turtle Trachemys scripta is one of a limited group of vertebrates that can withstand hours to days without oxygen. One facet of anoxic survival is the turtle's ability to maintain basal extracellular glutamate levels, whereas in most vertebrates, anoxia triggers massive excitotoxic glutamate release. We investigated glutamate release and reuptake in the anoxic turtle and the effects of adenosine and ATP-sensitive potassium (K(ATP)) channels on glutamate homeostasis. Striatal extracellular glutamate was measured in anesthetized T. scripta by microdialysis in normoxia and over 2-h anoxia. Glutamate release is decreased by 44% in the early anoxic turtle; this anoxia-induced decrease in glutamate release was prevented when K(ATP) channels and adenosine receptors were blocked simultaneously but not when either mechanism was blocked individually. We hypothesize that the continued release and reuptake of glutamate during anoxia help maintain neuronal tone and aid in the recovery of a functional neuronal network after long periods of anoxia, whereas activation of adenosine and/or K(ATP) conserves energy by reducing glutamate release and lowering transport costs.

Pharmacokinetics of fluconazole in loggerhead sea turtles (Caretta caretta) after single intravenous and subcutaneous injections, and multiple subcutaneous injections

Superficial and systemic mycotic infections are common among clinically ill sea turtles, which places growing importance on the establishment of pharmacokinetic-based dosage regimens for antifungal drugs. The pharmacokinetic properties of the antifungal drug fluconazole, after intravenous (i.v.) and subcutaneous (s.c.) injections, were studied in juvenile loggerhead sea turtles (Caretta caretta) housed at 23.0-26.5 degrees C. Fluconazole pharmacokinetic properties were further assessed in a multiple-dose s.c. regimen derived from the pharmacokinetic parameters determined in the single-dose study. Pharmacokinetic parameters were calculated, using a two-compartment model, from plasma concentration-time data obtained after single i.v. and s.c. administrations of fluconazole at a dosage of 2.5 mg/ kg body weight in six juvenile sea turtles. Blood samples were collected at intervals through 120 hr after each dose, and the concentration of fluconazole in plasma was measured by reverse-phase high-performance liquid chromatography. The i.v. and s.c. elimination half-lives were 139.5 +/- 36.0 and 132.6 +/- 48.7 hr (mean +/- SD), respectively. Systemic clearance of fluconazole was 8.2 +/- 4.3 ml/kg x hr, and the apparent volume of distribution at steady state was 1.38 +/- 0.29 L/kg. A multiple-dose regimen was derived, which consisted of a loading dose of 21 mg/kg body weight and subsequent doses of 10 mg/kg administered through s.c. injection every 120 hr (5 days). This regimen was administered to four juvenile sea turtles for 10 days, and blood samples were taken to determine peak and trough plasma concentrations of fluconazole. The mean concentrations for the two peak concentrations were 16.9 +/- 1.1 and 19.1 +/- 2.8 microg/ml 4 hr after dosing, and the mean concentrations for the three trough concentrations were 7.2 +/- 2.2, 10.4 +/- 2.7, and 10.7 +/- 2.9 microg/ml 120 hr after dosing. The terminal half-life after the last dose was calculated at 143 hr. Throughout the multiple dosing, fluconazole concentrations remained above approximately 8 microg/ml, a concentration targeted when treating mycotic infections in humans. The results of this study suggest that fluconazole can be effectively administered to sea turtles at a dosage of 10 mg/kg every 5 days after a loading dose of 21 mg/kg.

Microclimates and energetics of free-living box turtles, Terrapene carolina, in South Carolina

We measured microclimate, field metabolic rates (FMRs), water flux, and activity patterns of telemetered box turtles (Terrapene carolina) in South Carolina from September 1987 to October 1988. Turtles were inactive for most of the winter and were active only sporadically during the rest of the year. Using the doubly labeled water method, we found that water flux averaged 8.8, 18.9, and 26.4 mL kg(-1) d(-1) in winter, spring, and summer/fall, respectively. FMR for the same periods averaged 0.028, 0.065, and 0.124 mL CO(2) g(-1) h(-1). Differences in FMR among seasons were significant but not between sexes. Using operative temperatures, we predicted standard and maximum metabolic rates of turtles. In winter, FMR was elevated above standard metabolic rates and close to maximum metabolic rates, whereas in spring and summer/fall, FMR fell midway between standard and maximum metabolic rates. We used a model to predict metabolic rates, geographical distribution, and potential reproductive output of box turtles across latitudes in eastern North America. Low FMR and low annual reproductive output may allow box turtles to survive and flourish in unpredictable resource environments by minimizing costs and risks, thereby maintaining greater lifetime reproductive success.

Complete suppression of protein synthesis during anoxia with no post-anoxia protein synthesis debt in the red-eared slider turtleTrachemys scripta elegans

Two previous studies of the effects of anoxia on protein synthesis in anoxia-tolerant turtles (Trachemys scripta elegans, Chrysemys picta bellii) have generated opposing results. Using the flooding-dose method, we measured the rate of protein synthesis following injection and incorporation of a large dose of radiolabelled phenylalanine to resolve the question of whether anoxia results in a downregulation of protein synthesis. After 1 h of anoxia, levels of protein-incorporated radiolabel indicated that protein synthesis rates in the intestine, heart, liver, brain, muscle and lungs were not significantly different from those of normoxic controls. However, from 1 to 6 h of anoxia, quantities of protein-incorporated radiolabel did not increase, suggesting that protein synthesis had ceased or had decreased below a measurable level. There was also no significant post-anoxia increase in protein synthesis rates above normoxic control levels during 3 h of recovery from anoxia. RNA-to-protein ratios did not change significantly in any tissue except the heart, in which RNA levels decreased below normoxic control levels after 6 h of anoxia. Except in the heart, downregulation of protein synthesis during anoxia does not appear to be mediated by changes in tissue RNA concentration.

Vitellogenin induction in painted turtle, Chrysemys picta, as a biomarker of exposure to environmental levels of estradiol

Ponds within cattle farms often support turtle and fish populations and are impacted by manure runoff. Cattle excrete metabolized (glucuronide-conjugated) hormones in feces and urine into these ponds, and bacteria cleave the glucuronide metabolites to active steroids, which can be stable for several weeks in wastewater. The objectives of this study were to (1) assess levels of xenoestrogens found in ponds near livestock pastures; and (2) assess whether these levels of xenoestrogens induce vitellogenin (VTG) in painted turtles in the laboratory and field. We collected water twice, 6 weeks apart, and placed turtle traps weekly into two ponds, which receive runoff from beef cattle pastures, and into one pond with no cattle farm effluents. Water E(2) levels were analyzed using C(18) solid phase extraction disks and detected in a radioimmunoassay (RIA). Plasma was collected from painted turtles (Chrysemys picta) captured from these ponds and VTG levels were measured via enzyme linked immunosorbent assay (ELISA). Nine additional turtles were collected from a pond at the South Carolina Botanical Gardens, which receives no farm runoff, and were exposed in the laboratory to nominal concentrations of 0.15, 1.5, and 15 ng/l estradiol (static renewal) over a 28-day period, followed by 14 days in clean water. Plasma samples were taken weekly for VTG measurement via ELISA. Levels of free estradiol in the water column of farm ponds range from 0.05 to 1.80 ng/l, as measured by RIA, and up to 7.4 ng/l as measured by ER-beta binding affinity. This is similar to what has been reported in streams receiving sewage treatment works (STW) effluents. In the laboratory, plasma VTG in male painted turtles could not be induced even at the high E(2) dose (9.45 ng/l) after 28 days. In the field, VTG levels were induced only in females when compared with animals from the SC Botanical Gardens. Adult male turtles need to be primed with high doses of E(2) prior to being able to respond to exogenous E(2). Given that males would not typically be sensitized in the wild, environmentally relevant levels of E(2) may not be sufficient to affect them. However, higher VTG levels in females could potentially change their reproductive fitness by altering egg size or by shifting energy allocations away from other survival needs. Long-term studies are needed to study potential impacts of VTG induction on female turtle reproductive success.

Reductions in systemic oxygen delivery induce a hypometabolic state in the turtle Trachemys scripta

We investigated the effects of vagal reductions in O(2) delivery on oxygen consumption (VO(2)) in the anesthetized freshwater turtle Trachemys scripta. Specifically, these experiments tested the hypothesis that reductions in arterial oxygen partial pressure (PO(2)) and/or systemic oxygen transport (SOT) trigger a metabolic downregulation. During electric stimulation of the efferent branch of the sectioned right vagus nerve (RVEF), systemic cardiac output decreased 60-70%, systemic PO(2) fell by approximately 30%, and SOT decreased by 60-70%. During RVEF simulation, VO(2) dropped approximately 35%. During control conditions, injection of the metabolic uncoupler 2,4-dinitrophenol (DNP) more than doubled VO(2), reflecting an increase in ATP turnover. RVEF stimulation after DNP injection produced similar cardiovascular and blood gas changes as before DNP, but VO(2) was higher than the VO(2) measured in untreated control animals, indicating that oxygen availability during RVEF stimulation is still sufficient to support VO(2) rates that are even higher than resting rates. We conclude that vagal stimulation triggers metabolic downregulation, primarily through the effects on oxygen transport, although the factor(s) that trigger the hypometabolism remain unknown. The PO(2) may still be an important messenger in metabolic control, but our results suggest that changes in SOT to the metabolically active tissues, rather than changes in PO(2) per se, play an important role in triggering hypometabolism in the freshwater turtle.

Photoreceptors and visual pigments in the red-eared turtle, Trachemys scripta elegans

Absorbance spectra of cone outer segments and oil droplets were recorded microspectrophotometrically in the retina of the red-eared turtle, Trachemys scripta elegans. There are four cone visual pigments, with lambda(max) = 617 nm (red sensitive), 515 nm (green sensitive), 458 nm (blue sensitive), and 372 nm (UV-sensitive). The red-sensitive pigment resides in single cones with red or orange oil droplets, and in both members of double cones. The principal member of the double cone contains an orange oil droplet, and the accessory member is droplet free. The green-sensitive pigment is situated in single cones with orange/dark yellow droplets. The blue-sensitive pigment is combined with the UV-absorbing oil droplet in single cones. The UV-sensitive pigment resides in single cones with clear oil droplets that exhibited virtually no absorbance down to 325 nm. Thus, seven types of cones can be identified based on their morphology, oil droplet color, and the visual pigment absorbance. At the moment, this is the most complex cone system described for vertebrates.