Snake Liver Research Articles

Features of the immunopathogenesis of infections caused by viroids and satellite viruses

One of the main molecular mechanisms of viroids that cause disease in plants is the blocking of ribonucleic acid functions of host cells by viroid ribonucleic acid. The variety of splicing options is due to viroid replication, which requires ribonucleic acid polymerase, ribonuclease, ligase, and deoxyribonucleic acid working on ribonucleic acid matrices. Viroids with faster replication are preferred. Identifying host proteins that interact with viroid ribonucleic acid is critical in the pathogenesis of viroid infections, which leads to gene expression changes of host plants. The study of the pathogenesis of plant infections caused by satellite viruses has shown that they have a common ancestor and that the satellite viruses suppress the reproduction of the helper virus. Satellite viruses require accessory viral proteins to encode capsid proteins for genome encapsulation and reproduction. Replication occurs in the cytoplasm and is induced by ribonucleic acid polymerase of the helper virus. Hepatitis D virus ribonucleic acid replication requires cell ribonucleic acid polymerase II. When the viral and endosomal membranes fuse, the ribonucleic acid of the hepatitis D virus moves into the nucleus, and antigenomic ribonucleic acid is produced, which is the template for the synthesis of matrix ribonucleic acids encoding delta protein. The minor delta antigen regulates ribonucleic acid editing, and the large delta antigen inhibits viral replication and induces a signal for the transport of ribonucleic acid from the cell nucleus to the cytoplasm, which ensures the assembly of new viral particles. Large and small delta antigens have been detected in the brain, liver, lungs, kidneys, and spleen of snakes by reverse transcriptase polymerase chain reaction, Western blotting, and immunohistochemical assays, indicating that all delta viruses possibly share a common ancestor that arose before the divergence of reptiles and mammals.

Heavy Metal Concentration in Neotropical Aquatic Snakes (Helicops pastazae) and Its Potential as a Bioindicator of Water Pollution.

The purpose of this study was to test the potential role of the aquatic snake Helicops pastazae as an indicator of water pollution caused by heavy metals. In particular, we tested whether the total heavy metal concentration is related to (1) the position (upstream vs downstream) of the sampling point and its distance from the point where wastewater is discharged; (2) the taxonomic group studied: piscivorous snakes vs characid fish that occupy the same habitats; and (3) the organ or tissue examined: snake liver versus muscle. We used atomic absorption spectrophotometry with electrothermal atomization to quantify cadmium (Cd), chromium (Cr) and lead (Pb) and found significant differences between some of the sampling points, with particularly high metal concentrations detected upstream at point 1. However, we found no clear spatial pattern nor any significant differences in the concentration of any of the metals in fish and snake muscle, suggesting that both species accumulate similar amounts of the sampled elements. With regard to interactions, snake liver had the highest concentrations of Cd, while muscle had the highest concentrations of Pb and Cr, which may indicate tissue affinity differences for certain metals. Altogether, our results indicate that H. pastazae accumulates contaminants differentially, depending on the tissue and location, which highlights their potential as bioindicators of water contamination. Further research is necessary to understand their role as bioindicators based on extensive sampling and environmental contaminant data.

Liver retraction using an L-shaped retractor during sleeve gastrectomy.

The Nathanson liver retractor (NLR) and the snake liver retractor (SLR) are commonly used in bariatric surgery and their use is associated with some disadvantages. We developed an L-shaped liver retractor (LLR) and herein evaluated its efficacy and safety. The present retrospective study enrolled patients undergoing sleeve gastrectomy in our department between June 2014 and December 2020. The patients were divided into three groups according to the liver retractor used (LLR, SLR or NLR) for a comparative analysis of the efficacy and safety of the devices. The procedural time (PT) of each retractor type, defined as the time from retractor insertion to liver fixation, was compared. In total, 140 patients successfully underwent laparoscopic sleeve gastrectomy. The LLR, SLR and NLR were used in 37, 91, and 12 of these patients, respectively. The PT for the LLR was the shortest. AST/ALT elevation was significantly more frequent in the NLR group than in the SLR group and tended to be less frequent in the LLR group in comparison to the NLR group (p = 0.09). The length of hospital stay in the NLR group was significantly longer in comparison to the LLR group. Our study suggested that the LLR was superior to the conventional liver retractors used in sleeve gastrectomy.

Chlorinated Paraffins in Two Snake Species from the Yangtze River Delta: Tissue Distribution and Biomagnification

Very-short, short-, medium-, and long-chain chlorinated paraffins (vSCCPs, SCCPs, MCCPs, and LCCPs, respectively) were analyzed in different tissues of the terrestrial short-tailed mamushi (Gloydius brevicaudus) and the semi-aquatic red-backed rat snake (Elaphe rufodorsata) from the Yangtze River Delta, China. The total CP concentrations in liver, muscle, and adipose tissues in the two snake species were in the range of 2500-24 000, 4900-48 000, and 12-630 ng/g lw, respectively. Tissue burdens indicated that vSCCPs (C6-9) and SCCPs (C10-13) preferentially distributed to snake liver, while adipose was an important storage site and sink of MCCPs (C14-17) and LCCPs (C>18). On a lipid weight basis, vSCCPs and SCCPs were found in highest concentrations in red-backed rat snake liver and MCCPs and LCCPs in muscle, whereas for short-tailed mamushi, all CP groups were predominant in muscle, probably reflecting ecosystem/food web differences. Moreover, vSCCPs, SCCPs, MCCPs, and LCCPs were found to be biomagnified from black-spotted frogs to red-backed rat snakes with mean (maximum) biomagnification factors of 2.2 (3.4), 1.9 (3.7), 1.8 (2.8), and 1.7 (4.5), respectively. This is the first field study of biomagnification potential involving vSCCPs and LCCPs and highlights the need to include all CPs in studies.

Effect of hypothermia on the functional activity of liver mitochondria of grass snake (Natrix natrix): inhibition of succinate-fueled respiration and K+ transport, ROS-induced activation of mitochondrial permeability transition.

The article considers the comparative analysis of the functional activity of mitochondria isolated from the liver of grass snakes, Natrix natrix (Linnaeus, 1758) that were kept at different temperatures (23-26°C and 4-5°C). It was found that liver mitochondria of hypothermia-exposed grass snakes are characterized by weak coupling of oxidative phosphorylation as compared to mitochondria of active animals which is caused by inhibition of succinate-fuelled respiration in ADP-stimulated state, as well as by activation of basal non-phosphorylating rate. Inhibition of mitochondrial respiration in hibernating animals is associated with a decrease in the activity of the respiratory chain complexes of organelles. A significant decrease in the rate of K+ transport in the liver mitochondria of hibernating animals has been established. Under these conditions, a decrease in the calcium capacity of the organelles was also revealed, which indicates a decrease in the resistance of the mitochondria of hibernating animals to the induction of the Ca2+-dependent mitochondrial pore. All these changes in the functional activity of mitochondria are observed on the background of increasing H2O2 production as well as increasing the proportion of polyunsaturated fatty acids in phospholipid composition of mitochondrial membranes, which are the targets of reactive oxygen species. It can lead to increased formation of lipid peroxides and activation of destructive processes associated with the induction of Ca2+-dependent mitochondrial pore.

Sex and seasonal differences in mRNA expression of estrogen receptor α (ESR1) in red-sided garter snakes (Thamnophis sirtalis parietalis)

Estrogens are important regulators of reproductive physiology including sexual signal expression and vitellogenesis. For the regulation to occur, the hormone must bind and activate receptors in target tissues, and expression of the receptors can vary by sex and/or season. By simultaneously comparing circulating hormone levels with receptor expression, a more complete understanding of hormone action can be gained. Our study species, the red-sided garter snake (Thamnophis sirtalis parietalis), provides an excellent opportunity to study the interaction between sex steroid hormones and receptor expression in addition to sexual dimorphism and seasonality. During the spring mating season, male garter snakes rely exclusively on the female’s skin-based, estrogen-dependent sex pheromone to direct courtship. Males can be stimulated to produce this sexual attractiveness pheromone by treatment with estradiol (E2), which also induces male vitellogenesis. Estrogen receptors (ESRs) are required to transduce the effects of estrogens, thus we used quantitative RT-PCR to analyze expression of ESR alpha (ERα; gene ESR1) mRNA in the skin and liver of wild caught male and female garter snakes across simulated spring and fall conditions in the laboratory. While ESR1 was present in the skin of both sexes, there were no sex or seasonal differences in expression levels. Liver expression of ESR1, however, was sexually dimorphic, with females showing greatest expression in fall when circulating E2 concentrations were lowest. There were no statistically significant correlations between E2 and ESR1 expression. Our data suggest that the skin of both sexes is sensitive to estrogen signaling and thus the production of sex pheromone is dependent on bioavailable levels of E2. Female expression of ESR1 in the liver may increase in the fall to prime energy storage mechanisms required for vitellogenesis the following year.

Differential transcript profile of inhibitors with potential anti-venom role in the liver of juvenile and adult Bothrops jararaca snake.

BackgroundSnakes belonging to the Bothrops genus are vastly distributed in Central and South America and are responsible for most cases of reported snake bites in Latin America. The clinical manifestations of the envenomation caused by this genus are due to three major activities—proteolytic, hemorrhagic and coagulant—mediated by metalloproteinases, serine proteinases, phospholipases A2 and other toxic compounds present in snake venom. Interestingly, it was observed that snakes are resistant to the toxic effects of its own and other snake’s venoms. This natural immunity may occur due the absence of toxin target or the presence of molecules in the snake plasma able to neutralize such toxins.MethodsIn order to identify anti-venom molecules, we construct a cDNA library from the liver of B. jararaca snakes. Moreover, we analyzed the expression profile of four molecules—the already known anti-hemorrhagic factor Bj46a, one gamma-phospholipase A2 inhibitor, one inter-alpha inhibitor and one C1 plasma protease inhibitor—in the liver of juvenile and adult snakes by qPCR.ResultsThe results revealed a 30-fold increase of gamma-phospholipase A2 inhibitor and a minor increase of the inter-alpha inhibitor (5-fold) and of the C1 inhibitor (3-fold) in adults. However, the Bj46a factor seems to be equally transcribed in adults and juveniles.DiscussionThe results suggest the up-regulation of different inhibitors observed in the adult snakes might be a physiological adaptation to the recurrent contact with their own and even other snake’s venoms throughout its lifespan. This is the first comparative analysis of ontogenetic variation of expression profiles of plasmatic proteins with potential anti-venom activities of the venomous snake B. jararaca. Furthermore, the present data contributes to the understanding of the natural resistance described in these snakes.

Genetic and Proteomic characterization of Bile Salt Export Pump (BSEP) in Snake Liver

Snake gallbladder, a traditional Chinese medicine, has been believed in various Asian countries to improve visual acuity and alleviate rheumatism. Bile acids, a major component of the gallbladder, are toxic to the liver and kidney in humans and animals due to its detergent effects, while also exhibiting therapeutic effects due to an increase in the gallbladder contractions of muscle strips in patients with cholesterol gallstones. Secretion of bile acids in human and mammals depends on the bile salt export pump (BSEP), a liver-specific adenosine triphosphate (ATP)-binding cassette transporter encoded by ABCB11. However, the presence of BSEP in snakes has not been thoroughly explored. Here we confirm the existence of BSEP and its coding DNA sequence in snakes on both the proteomic and genetic level. This work provides information on the snake ABCB11 sequence and helps further potential genetic manipulation to affect bile salt metabolism. Our study provides the foundation for research on bile acid production from snakes by using modern genetic and proteomic methodologies.

Oxidative stress biomarkers, cholinesterase activity and biotransformation enzymes in the liver of dice snake (Natrix tessellata Laurenti) during pre-hibernation and post-hibernation: A possible correlation with heavy metals in the environment

We investigated in the liver of dice snakes during pre- and post-hibernation changes in the following antioxidant parameters: total, manganese and copper zinc containing superoxide dismutases (Tot SOD, MnSOD, CuZn SOD, respectively), catalase (CAT), glutathione peroxidase (GSH-Px), glutathione reductase (GR) and the concentrations of total glutathione (GSH) and sulfhydryl groups (–SH). In addition, we examined the expression of phase I biotransformation enzyme cytochrome P4501A (CYP1A) and the activity of phase II biotransformation enzyme glutathioneS-transferase (GST), the level of lipid peroxidation (by measuring the thiobarbituric acid-reactive substances (TBARS)), cholinesterase activity (ChE) and metallothionein expression (MT). We also measured the concentrations of heavy metals, including Al, Cd, As, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb and Zn in the water and snake liver during both periods. During the post-hibernation period, the activities of Tot SOD, CuZn SOD and GST and the concentration of GSH were significantly decreased, while GSH-Px and GR activities, the concentrations of –SH groups and TBARS were significantly increased. The activities of Mn SOD, CAT and ChE, and the relative amounts of CYP1A and MT did not significantly change during the investigated periods. The observed differences in the examined parameters probably represent adaptive physiological responses to sudden changes in tissue oxygenation during arousal from hibernation. Our findings also indicate that the accumulated metals modulated the responses of the examined parameters during the investigated periods.

Biochemical parameters in the blood of grass snakes (Natrix natrix) in ecosystems under varying degrees of anthropogenic influence

The grass snake Natrix natrix (Linnaeus, 1758) is a partly hygrophilous species, distributed throughoutUkraine. This snake may be considered as a test object for environmental biomonitoring. Modern biochemical methods make it possible to obtain new scientific data on the effects of anthropogenic pressure on reptiles. Blood is a sensitive and informative indicator of the condition of an organism as it responds quickly to most changes in exogenous and endogenous factors, and reflects negative influences on both individual and, indirectly, populations. Changes in biochemical parameters may be used as biomarkers of the state of health of reptiles in ecosystems under varying degrees of anthropogenic pressure. Due the increase in anthropogenic influence the development and introduction of new methods of perceptual research, collection of up-to-date information and development of a database of reptile biochemical parameters have become an urgent priority. We collected mature individuals of the grass snake in floodplain ecosystems on the right bank of the Dnieper River in Dnipropetrovsk city. Grass snakes from floodplain habitats on the left bank of theSamaraRiver (O.L. Belgard Prysamarskii International Biosphere Station, Novomoskovsk district, Dnipropetrovsk province) were studied as the control specimens. Our study demonstrated statistically significant differences between snakes from the study sites in the amount of albumin, urea and urea nitrogen, and inorganic phosphorus, as well as in alanine aminotransferase (ALT) and alkaline phosphatise (AP) activity. The amount of albumin in the blood serum of specimens from the anthropogenically transformed areas was significantly lower (by 25%) than in that of the snakes caught in the control habitats. Decrease of the albumin concentration usually indicates abnormal processes in the kidneys and liver. According to the changes observed in the concentration of albumin, a corresponding increase in the albumin to globulin ratio by about 30% was found. A statistically significant increase in alkaline phosphatase activity may demonstrate negative physiological changes in tissues of the liver and bones. Increased activities of ALT and AP indicate certain changes in the physiological condition of the liver of snakes from the anthropogenically transformed site. Other studied parameters did not exceed the limits found for different species of reptiles. Significant differences between certain biochemical parameters in the serum of snakes from the studied regions may reflect pathological processes in the grass snakes from transformed ecosystems, mainly in their liver and kidneys. The results can be used in future studies as benchmarks for assessing the condition of the organism of this species in the conditions of anthropogenic stress.

Gene expression of components of the insulin/insulin-like signaling pathway in response to heat stress in the garter snake,Thamnophis elegans

The insulin/insulin-like signaling (IIS) pathway is an evolutionary conserved molecular signaling pathway that regulates growth, reproduction, stress resistance, and longevity in response to nutrition and external stress. While the constituents of this pathway and their functions are relatively well understood in laboratory model animals, they have not been explored in many other organisms, with notable exceptions in the fisheries literature. We tested for the gene expression of four key components of this pathway in the garter snake (Thamnophis elegans) liver, and determine how the transcription of these components responds to heat stress. We found that the two insulin-like growth factor ligands (IGF-1 and IGF-2) and the receptors (IGF-1 Receptor and M6P/IGF-2 Receptor, or IGF-1R and IGF-2R) are expressed in garter snake liver tissue. Under normal laboratory conditions, IGF-2 and IGF-2R are expressed at a higher level than IGF-1 and IGF-1R. In response to heat stress, IGF-1 expression remained the same, IGF-2 expression decreased, and the expression of both receptors increased. These results demonstrate that elements of the IIS pathway are responsive to heat stress in snakes. Further studies are needed to fully understand the biological consequences of this response.

The Effectiveness of a Snake Liver Retractor during Needlescopic Grasper Assisted Sinlge-Incision Laparoscopic Cholecystectomy in the Aspect of Securing a Critical View of Safety

Myung-Guen Cha, M.D., Tae-Seok Kim, M.D., Kee-Hwan Kim, M.D., Ph.D., Chang-Hyeok An, M.D., Ph.D., Jeong-Soo Kim, M.D., Ph.D.. J Minim Invasive Surg 2013;16:34-8. https://doi.org/10.7602/jmis.2013.16.3.34

Accelerated Evolution of Fetuin Family Proteins inProtobothrops flavoviridis(Habu Snake) Serum and the Discovery of an L1-Like Genomic Element in the Intronic Sequence of a Fetuin-Encoding Gene

Habu serum factor (HSF) and HSF-like protein (HLP) are fetuin family proteins isolated from Protobothrops flavoviridis (habu snake) serum with different physiological activities. A comparison of their cDNAs and intronic sequences revealed that nucleotide substitutions were primarily in protein-coding regions, and the substitution patterns indicated accelerated evolution of these proteins. Genomic DNA fragment analysis, including intron 1, revealed a 6.6-kb insertion homologous to the full-length mammalian LINE1 (L1) retrotransposable element (PfL1) only in the HLP gene. This segment retains an open reading frame (ORF) that encodes a reverse transcriptase (RT)-like protein (PfRT). We further found that a large number of homologous segments have dispersed in the habu snake genome, although we could not determine the enzymatic activities of their products. Moreover, an analysis of habu snake liver RNA indicated active transcription of the PfRT genes, suggesting that high levels of RT activity in this snake have driven the evolution of unique phenotypes of venom enzymes and serum inhibitors of them.

Proteomic profiling of liver from Elaphe taeniura, a common snake in eastern and southeastern Asia

Snake liver has been implicated in the adaptation of snakes to a variety of habitats. However, to date, there has been no systematic analysis of snake liver proteins. In this study, we undertook a proteomic analysis of liver from the colubrid snake Elaphe taeniura using a combination of two-dimensional electrophoresis (2-DE) and matrix-assisted laser desorption/ionization time of flightmass spectrometry (MALDI-TOF MS). We also constructed a local protein sequence database based on transcriptome sequencing to facilitate protein identification. Of the 268 protein spots revealed by 2-DE 109 gave positive MS signals, 84 of which were identified by searching the NCBInr, Swiss-Prot and local databases. The other 25 protein spots could not be identified, possibly because their transcripts were not be stable enough to be detected by transcriptome sequencing. GO analysis showed that most proteins may be involved in binding, catalysis, cellular processes and metabolic processes. Forty-two of the liver proteins identified were found in other reptiles and in amphibians. The findings of this study provide a good reference map of snake liver proteins that will be useful in molecular investigations of snake physiology and adaptation.

Predators usurp prey defenses? Toxicokinetics of tetrodotoxin in common garter snakes after consumption of rough-skinned newts

Snakes are common predators of organisms, such as amphibians, with toxic defenses that can be lethal to other predators. Because snakes do not have the option of dissecting prey into edible versus inedible components, they face a full dose of any chemical defenses encountered during attempted predation. This limitation has likely resulted in intense selection favoring the evolution of alternative mechanisms for dealing with prey toxins. These mechanisms can be physiological (e.g., resistance to prey toxins) or behavioral (e.g., toxin sampling and rejection). When physiological resistance arises, the possibility of bioaccumulation of a toxin results. We examined the coevolutionary interaction between the common garter snake (Thamnophis sirtalis) and the rough-skinned newt (Taricha granulosa), which contains a powerful neurotoxin called tetrodotoxin (TTX). In some populations syntopic with newts, individuals of T. sirtalis have evolved resistance to TTX. We examined the persistence of TTX in T. sirtalis after administration of an oral dose of TTX to investigate the possibility that snakes are sequestering TTX. The half-life of TTX in snake liver was estimated at 8.1 days. Accordingly, clearance of 99% of a single dose of TTX averages 61 days. Negative fitness consequences of intoxication during and after newt consumption may be balanced by co-opting the newts’ chemical defense for protection from the snakes’ own predators. Accounting of the coevolutionary dynamic between snakes and newts must incorporate post-consumption affects of lingering TTX.

Phospholipase A2 inhibitors (βPLIs) are encoded in the venom glands of Lachesis muta (Crotalinae, Viperidae) snakes

Phospholipase A2 inhibitors (PLIs) are glycoproteins secreted by snake liver into the circulating blood aiming the self-protection against toxic venom phospholipases A2. In the present study, we describe the first complete nucleotide sequence of a βPLI from venom glands of a New World snake, Lachesis muta. The deduced primary structure was compared to other known βPLIs and recent literature findings of other possible roles of PLIs in snakes are discussed.

Identification of the B Subtype of γ-Phospholipase A2 Inhibitor from Protobothrops flavoviridis Serum and Molecular Evolution of Snake Serum Phospholipase A2 Inhibitors

A cDNA encoding a novel phospholipase A(2) (PLA(2)) inhibitor (PLI) was isolated from a Protobothrops flavoviridis snake (Tokunoshima island, Japan) liver cDNA library. This cDNA encoded a signal peptide of 19 amino acids followed by a mature protein of 181 amino acids. Its N-terminal amino acid sequence was completely in accord with that of a PLI, named PLI-II, previously found in P. flavoviridis serum. PLI-II showed a high similarity in sequence to the B subtype of gammaPLI, denoted gammaPLI-B, isolated from Agkistrodon blomhoffii siniticus serum. Thus, PLI-II is P. flavoviridis serum gammaPLI-B. Since PLI-I, previously isolated from P. flavoviridis serum, can be assigned as gammaPLI-A, P. flavoviridis serum contains both A and B subtypes of gammaPLI. Phylogenetic analysis of gammaPLIs from the sera of various kinds of snakes, Elapinae, Colubrinae, Laticaudinae, Acanthophiinae, Crotalinae, and Pythonidae, based on the amino acid sequences revealed that A and B subtypes of gammaPLIs are clearly separated from each other. It was also found that phylogenetic topologies of gammaPLIs are in good agreement with speciation processes of snakes. The BLAST search followed by analyses with particular Internet search engines of proteins with Cys/loop frameworks similar to those of PLI-II and PLI-I revealed that gammaPLI-Bs, including PLI-II and PLI-II-like proteins from mammalian sources, form a novel PLI-II family which possesses the common Cys/loop frameworks in the anterior and posterior three-finger motifs in the molecules. Several lines of evidence suggest that PLI-II is evolutionarily ancestral to PLI-I.

BUMPUS IN THE SNAKE DEN: EFFECTS OF SEX, SIZE, AND BODY CONDITION ON MORTALITY OF RED-SIDED GARTER SNAKES

Abstract Huge breeding aggregations of red-sided garter snakes (Thamnophis sirtalis parietalis) at overwintering dens in Manitoba provide a unique opportunity to identify sources of mortality and to clarify factors that influence a snake's vulnerability to these factors. Comparisons of sexes, body sizes, and body condition of more than 1000 dead snakes versus live animals sampled at the same time reveal significant biases. Three primary sources of mortality were identified. Predation by crows, Corvus brachyrhynchos (590 snakes killed), was focussed mostly on small snakes of both sexes. Crows generally removed the snake's liver and left the carcass, but very small snakes were sometimes brought back to the nest. Suffocation beneath massive piles of other snakes within the den (301 dead animals) involved mostly small males and (to a lesser extent) large females; snakes in poor body condition were particularly vulnerable. Many emaciated snakes (in= 142, mostly females) also died without overt injuries, probably due to depleted energy reserves. These biases in vulnerability are readily interpretable from information on behavioral ecology of the snakes. For example, sex biases in mortality reflect differences in postemergence behavior and locomotor capacity, the greater attractiveness of larger females to males, and the high energy costs of reproduction for females.

Metal levels in blood, muscle and liver of water snakes (Nerodia spp.) from New Jersey, Tennessee and South Carolina

Reptiles, particularly snakes, could serve as bioindicators of contamination because some are comparatively long-lived, exhibit different trophic levels, and are at the top of their food chains. We test the null hypothesis that there are no differences in the concentrations of heavy metals in the blood, muscle and liver of water snakes (Nerodia spp.) from rivers in New Jersey, Tennessee and South Carolina. While the former site is in an urban/suburban area, the latter two sites are relatively rural and are located on Department of Energy sites. For the snakes from New Jersey, there were significant differences in metal concentrations among tissues for all metals, the highest levels for arsenic and selenium were in liver and kidney, for cadmium were in the liver, for chromium and lead were in skin, and for mercury and manganese were in the muscle. Body length was not correlated with metal levels, and there were more significant correlations for skin with internal tissues than for blood with other tissues. There were more significant correlations for mercury than for other metals. In comparing metal levels among states, levels were generally higher for snakes collected from South Carolina. These data indicate that, since water snakes accumulate contaminants differentially as a function of location, they can be useful bioindicators of environmental exposure to contaminants. Moreover, because of their wide geographical distribution and use of varying trophic compartments, this genus can be useful for cross-site comparisons.

Heavy Metal Concentrations in Northern Water Snakes (Nerodia sipedon) from East Fork Poplar Creek and the Little River, East Tennessee, USA

We compared the levels of arsenic, cadmium, chromium, lead, manganese, mercury, and selenium in the blood, kidney, liver, muscle, and skin of northern water snakes (Nerodia sipedon) collected from the upper reach of East Fork Poplar Creek (EFPC) within the United States Department of Energy's (USDOE's) Y-12 National Security Complex with concentrations in tissues of northern water snakes from a reference reach of the Little River downstream from the Great Smoky Mountains National Park in East Tennessee. Our objectives were to determine whether concentrations of these metals were higher in tissues of water snakes collected from EFPC compared with the reference site and if northern water snakes were suitable bioindicators of metal contamination. Except for chromium, metal levels were significantly higher in tissues (kidney, liver, muscle, and skin) of EFPC northern water snakes compared with those in tissues of snakes from the reference site. Although female northern water snakes were significantly larger than male snakes, their tissues did not contain significantly higher metal concentrations compared with those from male snakes, possibly because of maternal transfer of metals to eggs. This study was the first to examine the accumulation of contaminants resulting from the operations of the USDOE's Oak Ridge Reservation in snakes.