Genetic identification of novel poxviruses of cetaceans and pinnipeds.

Novel poxviruses were identified in skin lesions of several species of cetaceans and pinnipeds using polymerase chain reaction targeting DNA polymerase and DNA topoisomerase I genes of members of the subfamily Chordopoxvirinae. With the exception of parapoxviruses, no molecular data of marine mammal poxviruses were available to infer genetic and evolutionary relatedness to terrestrial vertebrate poxviruses. Viruses were assigned to a cetacean poxvirus 1 (CPV-1) group based on nucleotide and amino acid identities of gene fragments amplified from skin lesions of Asian bottlenose (Tursiops aduncus), Atlantic bottlenose (Tursiops truncatus), rough-toothed (Steno bredanensis), and striped (Stenella coeruleoalba) dolphins. A different poxvirus was detected in skin lesions of a bowhead whale (Balaena mysticetus) and provisionally assigned to a CPV-2 group. These viruses showed highest identity to terrestrial poxviruses of the genera Orthopoxvirus and Suipoxvirus. A novel species-specific poxvirus was also identified in skin lesions of Steller sea lions (Eumetopias jubatus). None of these poxviruses were found to have amplifiable hemagglutinin gene sequences. Novel parapoxviruses were also identified in skin lesions of Steller sea lions and spotted seals (Phoca largha). A significant degree of divergence was observed in sequences of Steller sea lion parapoxviruses, while those of spotted seals and harbor seals (Phoca vitulina) were highly conserved.

Organochlorine concentrations in bonnethead sharks (Sphyrna tiburo) from Four Florida Estuaries.

Because of their persistence in aquatic environments and ability to impair reproduction and other critical physiological processes, organochlorine (OC) contaminants pose significant health risks to marine organisms. Despite such concerns, few studies have investigated levels of OC exposure in sharks, which are fish particularly threatened by anthropogenic pollution because of their tendency to bioaccumulate and biomagnify environmental contaminants. The present study examined concentrations of 29 OC pesticides and total polychlorinated biphenyls (PCBs) in the bonnethead shark (Sphyrna tiburo), an abundant species for which evidence of reproductive impairment has been observed in certain Florida populations. Quantifiable levels of PCBs and 22 OC pesticides were detected via gas chromatography and mass spectrometry in liver of 95 S. tiburo from four estuaries on Florida's Gulf coast: Apalachicola Bay, Tampa Bay, Florida Bay, and Charlotte Harbor. In general, OC concentrations were significantly higher in Apalachicola Bay, Tampa Bay, and Charlotte Harbor S. tiburo in relation to the Florida Bay population. Because the rate of infertility has been shown to be dramatically higher in Tampa Bay versus Florida Bay S. tiburo, the present findings allude to a possible relationship between OC exposure and reproductive health that requires further investigation. Pesticide and PCB concentrations did not appear to significantly increase with growth or age in S. tiburo, suggesting limited potential for OC bioaccumulation in this species compared with other sharks for which contaminant data are available. Concentrations of OCs in serum and muscle were not correlated with those in liver, indicating that these tissues are poor surrogates for measuring internal OC burden in this species via nonlethal sampling procedures.

Use of human recombinant erythropoietin for the treatment of nonregenerative anemia in a rough-toothed dolphin (Steno bredanensis).

Erythropoietin, a glycoprotein growth hormone that is produced primarily in the kidneys, promotes mitosis and survival of erythroid progenitors. The recent synthesis of the human form of the hormone by recombinant technology has provided a new therapeutic option, which is being used in both human and veterinary medicine for treatment of various anemias. A mature male rough-toothed dolphin, Steno bredanensis, was treated with human recombinant erythropoietin in an attempt to resolve a nonregenerative anemia. Two i.m. injections 48 hr apart were associated with an almost immediate increase in circulating immature reticulocytes, total reticulocytes, and nucleated erythrocytes. Over the next several weeks, the hematocrit, hemoglobin, and erythrocyte counts returned to normal, and the animal was subsequently released back into the wild. Endogenous erythropoietin concentrations were determined for this animal as well as three other conspecifics by an enzyme-linked immunosorbent assay for human erythropoietin. These measurements showed circulating erythropoietin concentrations (5-20+ mU/ml) similar to those of most other mammals. This study suggests that human recombinant erythropoietin can be safely and effectively used in this species and may have applicability to other cetacean species for the treatment of nonregenerative anemia. Caution should be exercised during long-term use because production of antibodies to human recombinant and endogenous erythropoietin may lead to potentially serious side effects.

Serum steroid hormones including 11-ketotestosterone, 11-ketoandrostenedione, and dihydroprogesterone in juvenile and adult bonnethead sharks, Sphyrna tiburo.

Previous studies in the placental viviparous bonnethead shark, Sphyrna tiburo, have correlated 17 beta-estradiol, progesterone, testosterone, and dihydrotestosterone with reproductive events in both males and females. However, several key reproductive events, including implantation, maintenance of pregnancy, and parturition, did not correlate with these four steroid hormones. Therefore, the present study investigated three steroid hormones, 11-ketotestosterone, 11-ketoandrostenedione, and dihydroprogesterone, which have demonstrably important roles in the reproductive cycles of teleosts. It was hypothesized that one or more of these three hormones would correlate with specific reproductive events in S. tiburo. Concurrently, developmental (growth and/or maturation) analyses of these three steroids plus 17 beta-estradiol, progesterone, testosterone, and dihydrotestosterone were investigated in juvenile bonnethead sharks. Serum dihydroprogesterone concentrations were highest in mature females and 11-ketotestosterone concentrations were highest in mature males. In mature females, 11-ketoandrostenedione levels were elevated from the time of mating, through six months of sperm storage and another four months of gestation. At parturition concentrations became significantly lower and remained lower until mating occurred again in another two to three months. Serum 11-ketotestosterone concentrations were the highest at implantation though not significant. In mature males, significantly elevated serum levels of dihydroprogesterone occurred in April and May, near the start of annual testicular development. During growth in males, testosterone and dihydrotestosterone increased progressively and in females, testosterone increased progressively. At maturity in males, significant increases occurred in testosterone and 11-ketotestosterone concentrations while, in females, dihydroprogesterone, 11-ketotestosterone, 17 beta-estradiol, progesterone, testosterone, and dihydrotestosterone concentrations increased. This study shows that although testosterone may be the primary androgen in the bonnethead shark, other derived androgens may have important functions in growth, maturation, and reproduction. J. Exp. Zool. 284:595-603, 1999.

Serum concentrations of steroid hormones in the mature male bonnethead shark, Sphyrna tiburo.

The male bonnethead shark, Sphyrna tiburo, undergoes an annual cycle of spermatogenesis and testicular regression and recrudescence. In southwestern Florida populations, testicular development and spermatogenesis begin in late spring and peak in late summer, with mating not taking place until about 2 months after the peak. Steroid hormones, some of which are known to play influential, essential roles in spermatogenesis, were measured in the serum during a full annual cycle in mature males from a wild population. Serum 17beta-estradiol (E2), progesterone (P4), testosterone (T), and dihydrotestosterone (DHT) concentrations were determined by radioimmunoassay. Serum T, DHT, and P4 concentrations followed the pattern of testicular development and regression, with all three steroid hormones attaining the highest significant levels (P < 0. 001) in late summer and falling to the lowest levels in mid-winter. Serum E2 concentrations showed significant changes (P < 0.01) with a peak in early spring. Male bonnethead sharks had significantly lower concentrations of E2 (P < 0.001) and significantly higher concentrations of T, DHT (P < 0.001), and P4 (P < 0.05) than those published for females. When steroid concentrations were compared to a behavioral rating of stress, only P4 showed a significant correlation to the stress behavior (P = 0.0447), but the significance was much lower than the significant correlation of P4 by month (P < 0.001).

Serum steroid hormones and the reproductive cycle of the female bonnethead shark, Sphyrna tiburo.

The bonnethead shark Sphyrna tiburo reproduces by placental viviparity with one of the shortest gestation periods (4.5-5 months) known in sharks. In southwest Florida, mating in this species occurs in November, sperm is stored until ovulation/fertilization the following March-April, and parturition occurs in August. Serum concentrations of four steroid hormones (17 beta-estradiol, progesterone, testosterone, and dihydrotestosterone) were determined by radioimmunoassay over a complete reproductive cycle in mature females from a wild population. Serum 17 beta-estradiol and testosterone levels are high during mating and preovulatory stages. Preovulatory concentrations of testosterone are greater in female S. tiburo than in any other female elasmobranch previously studied. Progesterone levels are significantly elevated during preovulatory, ovulatory, and postovulatory stages, while serum dihydrotestosterone levels increase significantly during the preovulatory stage. Our study is the first to demonstrate a sustained rise in progesterone during gestation in a placental shark and suggests a regulatory role for this hormone during the period prior to implantation of the embryos in the uterus.