[Growth and oxygen consumption in embryonic and early postembryonic development of European pond turtle Emys orbicularis (Reptilia: Emydidae)]

Experiments on developing eggs of European pond turtle (Emys orbicularis) demonstrated S-shaped changes in the rate of oxygen consumption and body weight during embryonic development. The rate of oxygen consumption and weight progressively increased within 70 days after hatching. During embryogenesis, the rate of oxygen consumption decreased. After hatching, it increased but then decreased to a certain level, which remained constant to the end of the studied period. We observed unidirectional changes in oxygen consumption rate during embryonic period and this pattern was maintained after hatching as well. The coefficients of the allometric relationship between oxygen consumption and body weight were a = 0.33 and k = 0.52 during the embryonic period and a = 0.17 and k = 0.89 during the postembryonic period.

Laser ablation ICP-MS profiling and semiquantitative determination of trace element concentrations in desert tortoise shells: documenting the uptake of elemental toxicants

The outer keratin layer (scute) of desert tortoise shells consists of incrementally grown laminae in which various bioaccumulated trace elements are sequestered during scute deposition. Laser ablation ICP-MS examination of laminae in scutes of dead tortoises revealed patterns of trace elemental distribution from which the chronology of elemental uptake can be inferred. These patterns may be of pathologic significance in the case of elemental toxicants such as arsenic, which has been linked to both shell and respiratory diseases. Laser ablation transects, performed along the lateral surfaces of sectioned scutes, offered the most successful means of avoiding exogenous contamination that was present on the scute exterior. Semiquantitative determination of elemental concentrations was achieved using sulfur, a keratin matrix element, as an internal standard. The results presented here highlight the potential of laser ablation ICP-MS as a diagnostic tool for investigating toxic element uptake as it pertains to tortoise morbidity and mortality.

Adenosine and ATP-sensitive potassium channels modulate dopamine release in the anoxic turtle (Trachemys scripta) striatum

Excessive dopamine (DA) is known to cause hypoxic/ischemic damage to mammalian brain. The freshwater turtle Trachemys scripta, however, maintains basal striatal DA levels in anoxia. We investigated DA balance during early anoxia when energy status in the turtle brain is compromised. The roles of ATP-sensitive potassium (K(ATP)) channels and adenosine (AD) receptors were investigated as these factors affect DA balance in mammalian neurons. Striatal extracellular DA was determined by microdialysis with HPLC in the presence or absence of the specific DA transport blocker GBR-12909, the K(ATP) blocker 2,3-butanedione monoxime, or the nonspecific AD receptor blocker theophylline. We found that in contrast to long-term anoxia, blocking DA reuptake did not significantly increase extracellular levels in 1-h anoxic turtles. Low DA levels in early anoxia were maintained instead by activation of K(ATP) channels and AD receptors. Blocking K(ATP) resulted in a 227% increase in extracellular DA in 1-h anoxic turtles but had no effect after 4 h of anoxia. Similarly, blocking AD receptors increased DA during the first hour of anoxia but did not change DA levels at 4-h anoxia. Support for the role of K(ATP) channels in DA balance comes from normoxic animals treated with K(ATP) opener; infusing diazoxide but not adenosine into the normoxic turtle striatum resulted in an immediate DA decrease to 14% of basal values within 1.5 h. Alternative strategies to maintain low extracellular levels may prevent catastrophic DA increases when intracellular energy is compromised while permitting the turtle to maintain a functional neuronal network during long-term anoxia.

Trace element (Cd, Cu, Hg, Se, Zn) accumulation and tissue distribution in loggerhead turtles (Caretta caretta) from the Western Mediterranean Sea (southern Italy)

Cadmium (Cd), copper (Cu), mercury (Hg), selenium (Se) and zinc (Zn) were determined in the liver, kidney and muscle of 29 loggerhead turtles, Caretta caretta, from the South Tyrrhenian Sea (Western Mediterranean). No significant differences (p>0.05) were detected between males and females. Trace element concentrations were not influenced by the size of the specimen except Se in the liver, which was negatively correlated with the curved carapace length (p<0.001). Muscles generally displayed the lowest trace element burdens, with the exception of Zn which contained concentrations as high as 176 microgg-1dwt. Kidneys displayed the highest Cd and Se mean concentrations (57.2+/-34.6 and 15.5+/-9.1 microgg-1dwt, respectively), while liver exhibited the highest Cu and Hg levels (37.3+/-8.7 and 1.1+/-1.7 microgg-1dwt, respectively). Whichever tissue is considered, the toxic elements had elevated coefficients of variation (i.e. from 60% to 177%) compared to those of the essential ones (i.e. from 14% to 65%), which is a consequence of homeostatic processes for Cu, Se and Zn. Globally, the concentrations of Hg remained low in all the considered tissues, possibly the result of low trophic level in sea turtles. In contrast, the diet of loggerhead turtles would result in a significant exposure to Cd. Highly significant correlations between Cd and Cu and Zn in the liver and kidney suggest that efficient detoxification processes involving MT occur which prevent Cd toxicity in loggerhead turtles.

[Extrinsic cells, immunoreactive to Ca-binding protein, as sources of thalamic visual centres in tortoises]

Extrinsic sources of calcium-binding proteins involved in immunoreactive innervation of the visual thalamic nuclei Rot and GLd in turtles (Testudo horsfieldi and Emys orbicularis) were studied using HRP tracing method and immunohistochemistry. In 1.5-4.5 months after monocular enucleation calbindin (Calb)-, parvalbumin (Parv)- and calretinin (Calr)-labeling was found in fragments of degenerated retinal fibers in the contralateral optic tract and in some retinorecipient structures (optic tectum, GLd and GLv). Changes in GLd were detected in its neuropil part. in 2.0-3.5 months after unilateral ablation of tectum and pretectum, the densities of Parv-, Calb- and Aclr-immunoreactivity terminals and fibers were diminisched in the ipsilateral n. Rot, with the maximum effect seen in Parv. Following HRP injection into the visual thalamus (Rot and GLd), retrogradely labeled cells with Parv label only, were revealed in the ventrothalamic nucleus Enta, pretectal nucleus Ptv, and in all types of Ca-binding proteins (CaBPr) in separately labeled cells of the optic tectum. Thus, it has been shown that thalamic visual centers in turtles have multiple extrinsic cells, which serve as sources of CaBPr projections. The present data suggest that organization of CaBPr inputs to visual thalamus in reptiles (turtle) and higher amniotes are fundamentally similar.

Negotiating brain anoxia survival in the turtle

The turtle brain's extraordinary ability to tolerate anoxia is based on constitutive and expressed factors. Constitutive factors that predispose for anoxia tolerance include enhanced levels of glycogen stores, increased densities of protective receptors, elevated antioxidant capacities and elevated heat shock protein. However, to survive an anoxic insult, three distinct phases must be negotiated successfully. (1) A coordinated downregulation of ATP demand processes to basal levels. This phase, which takes 1-2 h, includes a reduction in voltage-gated K(+) (Kv) channel transcription and a substantial increase in Hsp72 and Hsc73 levels. During this period, adenosine and K(ATP) channels mediate several key events including channel arrest initiation and a reduction in the release of excitatory amino acids (EAAs). (2) Long-term survival (days) at basal levels of ATP expenditure. Neuronal network integrity is preserved through the continued operation of core activities. These include periodic electrical activity, an increased release of GABA and a continued release of glutamate and dopamine. Adenosine and GABA modulate the glutamate release. There is a further increase in Hsc73, indicating a 'housekeeping' role for this protein during this period. (3) A rapid upregulation of neuronal processes when oxygen becomes available to restore full function, together with the activation of protection mechanisms against reperfusion-generated reactive oxygen species.

Clinical perspectives: neuroprotection lessons from hypoxia-tolerant organisms

An effective treatment for brain ischemia is a pressing medical need. Research on brain ischemia has largely focused on understanding the mechanisms of neuron death as a way of identifying targets for therapy. An attractive alternative approach is to identify the survival strategies of hypoxia-tolerant neurons. The adaptation of vertebrate neurons to hypoxia occurs in at least three major ways: (1) as a constitutive property of neurons in anoxia-tolerant turtles and fish, (2) as a property of intra-uterine and early post-natal mammalian development, and (3) as part of a slower, chronic process, as in acclimitization to high altitude. Research on hypoxia-tolerant neurons has already revised several earlier concepts, including the role of calcium in cell death and survival, and the value of N-methyl-d-aspartate (NMDA) receptor antagonism. A broad and fundamental understanding of how neurons adapt to hypoxia is likely to help guide efforts to find new treatments for brain hypoxia and ischemia.

Secretory proteins in the reproductive tract of the snapping turtle, Chelhydra serpentina

SDS-polyacrylamide gel electrophoresis was used to separate the secretory proteins produced by the epithelial and endometrial glands of the uterine tube and uterus in the snapping turtle Chelydra serpentina. The proteins were analyzed throughout the phases of the reproductive cycle from May to August, including preovulatory, ovulatory, postovulatory or luteal, and vitellogenic phases. The pattern of secretory proteins is quite uniform along the length of the uterine tube, and the same is true of the uterus, but the patterns for uterine tube and uterus are clearly different. We identify 13 major proteins in C. serpentina egg albumen. Bands co-migrating with 11 of these are found in the uterine tube, but at most 4 are found in the uterus, suggesting that the majority of the albumen proteins are most likely secreted in the uterine tube, not in the uterus. Although some of the egg albumen proteins are present in the uterine tube only at the time of ovulation, most of the bands corresponding to albumen proteins are present throughout the breeding season even though the snapping turtle is a monoclutch species. These results suggest that the glandular secretory phase in the uterine tube is active and quite homogeneous in function regardless of location or phase of the reproductive cycle.

PHARMACOKINETICS OF OXYTETRACYCLINE IN LOGGERHEAD SEA TURTLES (CARETTA CARETTA) AFTER SINGLE INTRAVENOUS AND INTRAMUSCULAR INJECTIONS

The pharmacokinetics of oxytetracycline in 2-yr-old loggerhead sea turtles (Caretta caretta) after single i.v. and i.m. injections were studied for biologic marking and therapeutic applications. Twenty juvenile turtles were divided into two treatment groups. Ten animals received 25 mg/kg of oxytetracycline i.v. and 10 received the same dosage i.m. Plasma oxytetracycline concentrations were analyzed by reverse-phase high-performance liquid chromatography. Data from the i.v. route best fit a three-compartment model, whereas noncompartmental analysis was used to compare data from both the i.v. and i.m routes. For the i.v. route, means for maximum plasma concentration, terminal phase half-life, systemic clearance, and apparent volume of distribution at steady state were 6.6 microg/ml, 66.1 hr, 290.7 ml/hr/kg, and 18.4 L, respectively. For the i.m. route, means for systemic availability, maximum plasma concentration, and elimination half-life were 91.8%, 1.6 microg/ml, and 61.9 hr, respectively. The remarkably high apparent volume of distribution may possibly be associated with a deep compartment of drug disposition such as bone deposition associated with the large skeletal mass of turtles and the fact that these were well-nourished, growing juveniles. Although maximum plasma concentration by i.m. administration was lower than for the i.v. route, the long elimination time indicates that an infrequent dosing interval may be effective for sensitive bacteria.

Characterization of contaminants in snapping turtles (Chelydra serpentina) from Canadian Lake Erie Areas of Concern: St. Clair River, Detroit River, and Wheatley Harbour

PCBs, organochlorine pesticides and dioxins/furans in snapping turtle eggs and plasma (Chelydra serpentina) were evaluated at three Areas of Concern (AOCs) on Lake Erie and its connecting channels (St. Clair River, Detroit River, and Wheatley Harbour), as well as two inland reference sites (Algonquin Provincial Park and Tiny Marsh) in 2001-2002. Eggs from the Detroit River and Wheatley Harbour AOCs had the highest levels of p,p'-DDE (24.4 and 57.9 ng/g) and sum PCBs (928.6 and 491.0 ng/g) wet weight, respectively. Contaminant levels in eggs from St. Clair River AOC were generally higher than those from Algonquin Park, but similar to those from Tiny Marsh. Dioxins appeared highest from the Detroit River. The PCB congener pattern in eggs suggested that turtles from the Detroit River and Wheatley Harbour AOCs were exposed to Aroclor 1260. TEQs of sum PCBs in eggs from all AOCs and p,p'-DDE levels in eggs from the Wheatley Harbour and the Detroit River AOCs exceeded the Canadian Environmental Quality Guidelines. Furthermore, sum PCBs in eggs from Detroit River and Wheatley Harbour exceeded partial restriction guidelines for consumption. Although estimated PCB body burdens in muscle tissue of females were well below consumption guidelines, estimated residues in liver and adipose were above guidelines for most sites.

Monoaminergic systems in the brainstem and spinal cord of the turtlePseudemys scripta elegansas revealed by antibodies against serotonin and tyrosine hydroxylase

With the aim of gaining more insight into the monoaminergic regulation of spinal motor systems in the turtle, we have studied the distribution of 5-HT (5-HTir) and tyrosine hydroxylase immunoreactivity (THir) in the brainstem and spinal cord of Pseudemys scripta elegans. 5-HTir cell bodies were located in the midline in nucleus raphe inferior, nucleus raphe superior, and laterally in nuclei reticularis superior and inferior and nucleus reticularis isthmi. THir cell bodies were located in the commissural nucleus, nucleus tractus solitarii, the locus coeruleus-subcoeruleus complex, nuclei reticularis superior and inferior, the pretectal area, and substantia nigra. 5-HTir and THir tracts were found in lateral and ventral bundles superficially in the brainstem. 5-HTir fibers in the spinal cord were located in a large dorsolateral and a smaller ventrolateral tract. In the gray matter, a high concentration of 5-HTir fibers were observed in areas I-IV and in the lateral motor column of cervical and lumbar enlargements. Areas V-VIII and area X were less intensively innervated, with the lowest fibre concentration in areas VII-VIII and area X. Throughout the spinal cord, THir nerve fibres were located in the same areas but with a lower density. Small bipolar 5-HTir and THir cell bodies were found ventromedially to the central canal especially in cervical and lumbosacral segments. Large THir cells were found in area IX in the caudal sacral and coccygeal spinal cord. THir cerebrospinal fluid-contacting cells were also found in the most caudal part of the brainstem and the upper cervical spinal cord. The well developed spinal 5-HT system and the less developed THir system provides an anatomical explanation for the monoaminergic modulation of turtle motoneuron membrane properties, which has been observed in electrophysiological experiments.

Time-dependent expression of heat shock proteins 70 and 90 in tissues of the anoxic western painted turtle

Expression of the constitutive Hsp73, inducible Hsp72 and Hsp90 was investigated in brain, heart, liver and skeletal muscle of the anoxia-tolerant western painted turtle Chrysemys picta bellii in response to 2, 6,12, 18, 24 and 30 h forced dives and following 1 h recovery from 12, 24 and 30 h forced dives at 17°C. During a dive, expression of all three Hsps examined remained at control levels for at least 12 h in all tissues examined except the liver, where Hsp72 showed a decrease at 12 h, reaching a significant threefold decrease by 24 h. Brain and liver Hsp73, 72 and 90 expression increased two- to threefold at 18, 24 and 30 h. Heart and muscle Hsp73 and heart Hsp90 expression remained at normoxic levels throughout the entire dive, while heart and muscle Hsp72 and muscle Hsp90 increased two- to fourfold at 24 and 30 h. Following reoxygenation, Hsp expression increased in all tissues examined. These data indicate that increased Hsp expression is not critical in the early adaptation to anoxic survival and that short-term anoxia is probably not a stress for species adapted to survive long periods without oxygen. However, the late upregulation of heat shock proteins during anoxia suggests that stress proteins play a role in promoting long-term anoxia tolerance.

Force development, energy state and ATP production of cardiac muscle from turtles and trout during normoxia and severe hypoxia

The effects of hypoxia on energy economy of cardiac muscle were compared between the hypoxia-tolerant freshwater turtle at 20 degrees C and the hypoxia-sensitive rainbow trout at 15 degrees C. Isolated ventricular preparations were left either at rest or stimulated at 30 min(-1) to develop isometric twitch force. Under oxygenated conditions, twitch force and oxygen consumption were similar for the two species. Overall metabolism was reduced during severe hypoxia in both resting and stimulated preparations and under these conditions most of the ATP production was derived from anaerobic metabolism. During hypoxia, a metabolic depression of approximately 2/3 occurred for non-contractile processes in both turtle and trout preparations. During hypoxia, lactate production and residual oxygen consumption were similar in turtle and trout. Cellular energy state and phosphorylation potential decreased during severe hypoxia in both species and this reduction was more severe in preparations stimulated to contraction. However, in turtle ventricular preparations the energy state and phosphorylation potential stabilised at higher levels than in trout, and turtle preparations also maintained a higher twitch force throughout the hypoxic period. Moreover, twitch force relative to total ATP hydrolysis was markedly increased during hypoxia in turtle while this ratio was unchanged for trout. The main findings of this study are: (1) cellular energy liberation and the energy demand of non-contractile processes decreased to similar levels in hypoxic turtle and trout myocardium; (2) turtle myocardium maintained a substantially higher cellular energy state and twitch force development than trout myocardium during hypoxia and (3) the ratio of twitch force to ATP hydrolysis increased during hypoxia in turtle but was unchanged in trout. It is possible that this superior economy of the contracting turtle myocardium contributes to the remarkable hypoxia tolerance of freshwater turtles.

Effects of organochlorine compounds on cytochrome P450 aromatase activity in an immortal sea turtle cell line

Many classes of environmental contaminants affect the reproductive function of animals through interactions with the endocrine system. The primary components affected by endocrine active compounds (EACs) are the steroid receptors and the enzymes responsible for steroidogenesis. This study sought to develop an in vitro model for assessing EAC effects in sea turtles by examining their ability to alter cytochrome P450 aromatase (CYP19) activity. Aromatase is the enzyme responsible for the conversion of testosterone to estradiol. This enzyme is critical in the sexual differentiation of reptiles which demonstrate temperature-dependent sex determination. An immortal testis cell line GST-TS from a green sea turtle was grown in culture at 30 degrees C in RPMI 1640 media. The cells were exposed to three known aromatase inducers; dexamethasone (Dex), 8Br-cyclic AMP, or human chronic gonadotropin (HCG) and one aromatase inhibitor 4-androstenol-dione (4-OHA). In addition, the GST-TS cells were exposed to 0.1-30 microM atrazine and 3-100 microM 4,4'-DDE. The inducing compounds that have been shown to increase aromatase activity in other systems failed to induce aromatase activity in the GST-TS cells, yet exposure to the inhibiting compound, 4-OHA, did result in a significant reduction. Atrazine (0.1, 1.0 and 10 microM) significantly induced aromatase activity following a 24 h exposure, and 4,4'-DDE inhibited the activity but only at cytotoxic concentrations (100 microM). Based on these results, this in vitro model can be useful in examining the endocrine effects of EACs in sea turtles.

Lactate accumulation, glycogen depletion, and shell composition of hatchling turtles during simulated aquatic hibernation

We submerged hatchling western painted turtles Chrysemys pictaSchneider, snapping turtles Chelydra serpentina L. and map turtles Graptemys geographica Le Sueur in normoxic and anoxic water at 3°C. Periodically, turtles were removed and whole-body [lactate] and[glycogen] were measured along with relative shell mass, shell water, and shell ash. We analyzed the shell for [Na+], [K+], total calcium, total magnesium, Pi and total CO2. All three species were able to tolerate long-term submergence in normoxic water without accumulating any lactate, indicating sufficient extrapulmonary O2extraction to remain aerobic even after 150 days. Survival in anoxic water was 15 days in map turtles, 30 days in snapping turtles, and 40 days in painted turtles. Survival of hatchlings was only about one third the life of their adult conspecifics in anoxic water. Much of the decrease in survival was attributable to a dramatically lower shell-bone content (44% ash in adult painted turtles vs. 3% ash in hatchlings of all three species) and a smaller buffer content of bone (1.3 mmol g–1 CO2in adult painted turtles vs. 0.13–0.23 mmol g–1 CO2 in hatchlings of the three species). The reduced survivability of turtle hatchlings in anoxic water requires that hatchlings either avoid aquatic hibernacula that may become severely hypoxic or anoxic (snapping turtles), or overwinter terrestrially (painted turtles and map turtles).

Neurotransmitter actions on transient amacrine and ganglion cells of the turtle retina

We obtained intracellular recordings from transient, On-Off amacrine and ganglion cells of the turtle retina. We tested the ability of neurotransmitter agonists and antagonists to modify the responses to light stimuli. The metabotropic glutamate agonist, 2-amino-phosphonobutyric acid (APB), selectively blocked On responses, whereas the amino-3-hydroxy-5-methylisoxazole-4-proprionic acid (AMPA) receptor antagonist, GYKI, blocked both On and Off responses. Although GYKI appeared to block excitation completely, suggesting an absence of N-methyl-d-aspartate (NMDA)-mediated responses, it was found that in the presence of ionotropic gamma-aminobutyric acid (GABA) blockers, the excitatory postsynaptic potential (EPSP) was prolonged. The late component of the EPSP was blocked by the NMDA antagonist, D-2-amino-5-phosphopentanoic acid (D-AP5). Picrotoxin (PTX) and bicuculline (BCC) induced a mean hyperpolarization of -6.4 mV, suggesting a direct effect of GABA on transient amacrine and ganglion cells, since antagonism of a GABA-mediated inhibition of release of glutamate by bipolars would depolarize third-order neurons. The acetylcholine agonist, carbachol, or the nicotinic agonist, epibatidine, depolarized all On-Off neurons. This action was blocked by d-tubocurarine. Cholinergic inputs to On-Off neurons increase their excitability without altering the pattern of light responsiveness.

Heavy metals in tissues of loggerhead turtles (Caretta caretta) from the northwestern Adriatic Sea

Thirty-five specimens of Caretta caretta were collected dead along the Adriatic Sea coast from the Po Delta to the Reno mouth (Italy). Turtles were classified into four size categories ranging from 24.5 to 74 cm, by measuring the minimum straight-line carapace length (MSCL). Cd, Cu, Fe, Mn, Ni, and Zn levels were assessed in liver, lung, muscle and adipose tissue. Cd, Cu and Fe mainly accumulated in the liver (8.9, 23.7 and 1180 mg/kg dry mass [d.w.], respectively), and Mn in the lung (29.5 mg/kg d.w.). Levels of Ni were higher in adipose (22 mg/kg d.w.) than other tissues, while Zn concentrations were higher in muscle (about 140 mg/kg d.w.). Negative correlations with size were established for Zn in liver and Cu in adipose tissue, while positive correlations were observed for Mn and Ni in adipose tissue. Metal concentrations did not differ between males and females, nor between individuals found stranded and those victims of by-catch. On average, Cd, Cu, Mn and Ni concentrations in our specimens were higher than in loggerhead turtles and other species living in other areas. We hypothesize that trace metals could be used as "acquired markers" to help investigate migration routes of C. caretta.

Accumulation of Lactate by Frozen Painted Turtles (Chrysemys picta) and Its Relationship to Freeze Tolerance

Hatchling painted turtles (Chrysemys picta) survived freezing at -2 degrees C for 4 d, few recovered from freezing lasting 6 d, and none survived being frozen for 8 d. Whole-body glucose and lactate were low in animals that had not been subjected to cold and ice but increased precipitously in animals that were frozen for 2 d. Both metabolites continued to increase, but at a somewhat lower rate, in animals frozen for 4, 6, or 8 d. The increase in whole-body lactate reflects a reliance by frozen hatchlings on anaerobiosis, whereas the increase in glucose presumably results from mobilization of glycogen reserves to support anaerobic metabolism. Mortality of frozen hatchlings is correlated with the increase in whole-body lactate. Factors that may contribute to the observed correlation include a compromised capacity for individual organs to cope with the lactic acidosis that accompanies anaerobic metabolism and organ-specific depletion of energy reserves. Individual organs must rely on buffering and glucose reserves available in situ because blood of frozen hatchlings does not circulate. Thus, buffer from the shell cannot be transported to other organs, lactate cannot be sequestered in the shell, and glucose mobilized from liver glycogen is not available to supplement glucose reserves of other tissues. This integrated suite of physiological disruptions may limit tolerance of freezing to conditions with little or no ecological relevance.

Organochlorine contaminants in sea turtles: correlations between whole blood and fat

Monitoring toxic organochlorine (OC) compounds is an important aspect in wildlife studies, especially in protected species such as sea turtles. The goal of this study was to determine whether blood OC concentrations can predict those in adipose tissue of sea turtles. Blood offers many benefits for monitoring OCs. It can be collected nondestructively from live turtles and can be sampled repeatedly for continuous monitoring. Organochlorine concentrations in blood may better represent the exposure levels of target tissues, but blood concentrations may fluctuate more than those in fatty tissues following recent dietary exposure or lipid mobilization. Paired fat and blood samples were collected from 44 live, juvenile loggerhead sea turtles and 10 juvenile Kemp's ridley sea turtle carcasses. Organochlorines were analyzed using gas chromatography with electron capture detection and mass spectrometry. Lipid-normalized OC concentrations measured in the blood significantly correlated to levels found in the fat samples of both species. This result suggests that sea turtle blood is a suitable alternative to fatty tissues for measuring OCs because blood concentrations reasonably represent those observed in the paired fat samples. However, blood OC concentrations calculated on a wet-mass basis were significantly and inversely correlated to lipid content in the fat samples. Therefore, caution should be used when monitoring spatial or temporal trends, as OC levels may increase in the blood following mobilization of fat stores, such as during long migrations, breeding, or disease events.

Comparative analyses of serum vitellogenin levels in male and female Reeves' pond turtles ( Chinemys reevesii ) by an immunological assay

A quantitative immunological method was developed for measuring serum vitellogenin levels of Reeves' pond turtles (Chinemys reevesii) to investigate the effects of endocrine disruptors on the freshwater ecosystem. Vitellogenin was induced by injecting estradiol-17beta into C. reevesii turtles (adult females, juvenile females, and males) and was purified from the turtle serum by EDTA-MgCl2 precipitation followed by gel filtration. Using a polyclonal antibody raised against C. reevesii vitellogenin, an enzyme-linked immunosorbant assay was established. The detectable range, recovery of vitellogenin, and coefficient of variation in this assay were 0.0040-1.0 microg.ml(-1), 85.3-109% and 3.4-11.5%, respectively. This assay was also applicable for measurement of the concentrations of vitellogenins from other species, Japanese pond turtles (Mauremys japonica) and red-eared turtles (Trachemys scripta). The serum vitellogenin concentration of 131 C. reevesii turtles captured at a Japanese local river was measured by the assay. In females, vitellogenin ranged from 0.10 microg.ml(-1) to 15,000 microg.ml(-1) with two peaks, 0.10-1.0 microg.ml(-1) (juveniles) and 1,000-10,000 microg.ml(-1) (adults). However, in males, it ranged from 0.10 microg.ml(-1) to 0.60 microg.ml(-1), showing one peak, 0.10-0.20 microg.ml(-1). Therefore, if relatively high concentrations of vitellogenin are detected in males or juvenile females, it is suggested that they would have been exposed to xenobiotic estrogens.

Adrenomedullary and glycemic responses to ACTH, corticosterone, aldosterone, epinephrine and norepinephrine administrations in the soft-shelled turtle

The aim of the current investigation was to ascertain the role of ACTH and adrenal hormones on adrenomedullary and glycemic functions in soft-shelled turtles, Lissemys punctata punctata. All the experiments were carried out on sexually immature animals. Findings revealed that: (1) ACTH administration (0.5 IU/1.0 IU/2.0 IU per 100 g body wt. daily for 10 days) in all doses stimulated adrenomedullary function by increasing medullary cell nuclear diameter with elevations of norepinephrine, epinephrine and blood sugar levels. Only moderate and higher doses (50 microg/100 microg per 100 g body wt. daily for 10 days) of dexamethasone suppressed adrenomedullary activity and blood sugar level by reversing the changes to those of ACTH; the responses were dose-dependent. But these changes were no longer observed after ACTH treatment in dexamethasone (DMS) recipients (DMS: 100 microg/ 100 g body wt daily for the first 10 days and ACTH: 0.5 IU / 100 g body wt daily for the next 10 days); (2) Only moderate and higher doses (50 microg/100 microg per 100 g body wt daily for 10 days) of corticosterone increased adrenomedullary activity and blood sugar level and the responses were also dose-dependent. But aldosterone treatment in all doses (same as for corticosterone) had no significant effect on the adrenal medulla or blood sugar level; (3) Only moderate and higher doses of norepinephrine or epinephrine (same as for corticosterone) caused adrenomedullary atrophy with depletions of norepinephrine and epinephrine levels but elevated the glycemic level. The findings are briefly discussed.

Expression of Dmrt1 in a turtle with temperature-dependent sex determination

There is a variety of sex determining mechanisms among vertebrates. Many reptiles possess temperature-dependent sex determination (TSD), in which the incubation temperature of the egg determines the sex of the hatchling. The red-eared slider turtle, Trachemys scripta has often been used as a model system for examining the physiology of TSD. In the current study, the expression of Dmrt1 was examined during TSD in this turtle. Dmrt1 is a putative regulator of sex determination/differentiation and has been identified in a variety of vertebrates, including fishes, amphibians, reptiles, birds, and mammals. Specifically, Dmrt1 has been shown to be up-regulated in a male-specific pattern during embryonic development in many vertebrates. In the current study, the expression patterns of Dmrt1 were examined in the developing adrenal-kidney-gonad complexes of T. scripta during embryonic development. Using a quantitative competitive RT-PCR, Dmrt1 was shown to be up-regulated during the thermosensitive period of sex determination in males. In contrast, levels of Dmrt1 remained low in females throughout the thermosensitive period. These data suggest that the up-regulation of Dmrt1 may play a role in male sex determination/sex differentiation during TSD in T. scripta.

Arsenic accumulation in livers of pinnipeds, seabirds and sea turtles: subcellular distribution and interaction between arsenobetaine and glycine betaine

Concentrations of total arsenic and individual arsenic compounds were determined in liver samples of pinnipeds (northern fur seal Callorhinus ursinus and ringed seal Pusa hispida), seabirds (black-footed albatross Diomedea nigripes and black-tailed gull Larus crassirostris) and sea turtles (hawksbill turtle Eretmochelys imbricata and green turtle Chelonia mydas). Among these species, the black-footed albatross contained the highest hepatic arsenic concentration (5.8+/-3.7 microg/g wet mass). Arsenobetaine was the major arsenic species found in the liver of all these higher tropic marine animals. To investigate the cause of high accumulation of arsenobetaine, subcellular distribution of arsenic and relationship between arsenobetaine and glycine betaine concentrations were examined in the livers of these animals. There was no relationship between total arsenic concentration and its subcellular distribution in liver tissues. However, a significant negative correlation was found between arsenobetaine and glycine betaine concentrations in the liver of six species examined. This result may indicate that arsenobetaine is accumulated in these marine animals as an osmolyte along with glycine betaine, which is a predominant osmolyte in marine animals because the chemical structure and properties of arsenobetaine are similar to those of glycine betaine.

Plasma steroid and nutrient levels during the active season in wild Testudo horsfieldi

Plasma concentrations of sex steroids (testosterone and progesterone), proteins (total protein and albumin), lipids (phospholipids, cholesterol, and triglycerides), and minerals (calcium and phosphorus) were measured in wild Testudo horsfieldi in Uzbekistan, during the short, 3-month activity period (March-May, 1998). Testosterone concentration in males was highest (52 ng/ml) when they had just emerged from brumation (hibernation) in mid-March, which was also the beginning of the mating period, and fell in April. In females, progesterone peaked in mid-April (at 10 ng/ml), just before ovulation of the first clutches at the end of April and beginning of May. Testosterone levels in females and progesterone levels in males were low (<3 ng/ml) throughout the activity period. In general, the plasma concentrations of proteins, lipids, and phosphorus increased slowly in males, but more rapidly in females, during the activity season. These increases were particularly strong in females in the second half of April, coinciding with the peaks in female hormone levels. The changes in plasma hormones and nutrients reflected the timing of the different behaviours. The four first weeks of above-ground activity (mid-March to mid-April) by males, when they had high testosterone levels, were primarily allocated to fighting other males, courtship, and mating, while females spent much of that time feeding. Thereafter, both sexes concentrated on feeding. Females were probably preparing to ovulate in late-April, when their progesterone levels were highest and when plasma nutrient levels increased considerably.