Effects of depleted uranium on the reproductive success and F1 generation survival of zebrafish (Danio rerio).

Despite the well-characterized occurrence of uranium (U) in the aquatic environment, very little is known about the chronic exposure of fish to low levels of U and its potential effect on reproduction. Therefore, this study was undertaken to investigate the effects of environmental concentrations of depleted U on the reproductive output of zebrafish (Danio rerio) and on survival and development of the F1 embryo-larvae following parental exposure to U. For that purpose, sexually mature male and female zebrafish were exposed to 20 and 250 µg/L of U for 14 days and allowed to reproduce in clean water during a further 14-day period. At all sampling times, whole-body vitellogenin concentrations and gonad histology were analyzed to investigate the effects of U exposure on these reproductive endpoints. In addition, accumulation of U in the gonads and its genotoxic effect on male and female gonad cells were quantified. The results showed that U strongly affected the capability of fish to reproduce and to generate viable individuals as evidenced by the inhibition of egg production and the increased rate of mortality of the F1 embryos. Interestingly, U exposure resulted in decreased circulating concentrations of vitellogenin in females. Increased concentrations of U were observed in gonads and eggs, which were most likely responsible for the genotoxic effects seen in fish gonads and in embryos exposed maternally to U. Altogether, these findings highlight the negative effect of environmentally relevant concentrations of U which alter the reproductive capability of fish and impair the genetic integrity of F1 embryos raising further concern regarding its effect at the population level.

Aurelia aurita (Cnidaria) oocytes' contact plate structure and development.

One of the A. aurita medusa main mesoglea polypeptides, mesoglein, has been described previously. Mesoglein belongs to ZP-domain protein family and therefore we focused on A.aurita oogenesis. Antibodies against mesoglein (AB RA47) stain the plate in the place where germinal epithelium contacts oocyte on the paraffin sections. According to its position, we named the structure found the "contact plate". Our main instrument was AB against mesoglein. ZP-domain occupies about half of the whole amino acid sequence of the mesoglein. Immunoblot after SDS-PAGE and AU-PAGE reveals two charged and high M(r) bands among the female gonad germinal epithelium polypeptides. One of the gonads' polypeptides M(r) corresponds to that of mesogleal cells, the other ones' M(r) is higher. The morphological description of contact plate formation is the subject of the current work. Two types of AB RA47 positive granules were observed during progressive oogenesis stages. Granules form the contact plate in mature oocyte. Contact plate of A.aurita oocyte marks its animal pole and resembles Zona Pellucida by the following features: (1) it attracts spermatozoids; (2) the material of the contact plate is synthesized by oocyte and stored in granules; (3) these granules and the contact plate itself contain ZP domain protein(s); (4) contact plate is an extracellular structure made up of fiber bundles similar to those of conventional Zona Pellucida.

Ultrastructural effects on gill, muscle, and gonadal tissues induced in zebrafish (Danio rerio) by a waterborne uranium exposure.

Experiments on adult zebrafish (Danio rerio) were conducted to assess histopathological effects induced on gill, muscle, and gonadal tissues after waterborne uranium exposure. Although histopathology is often employed as a tool for the detection and assessment of xenobiotic-mediated effects in aquatic organisms, few studies have been dedicated to the investigation of histopathological consequences of uranium exposure in fish. Results showed that gill tissue architecture was markedly disrupted. Major symptoms were alterations of the secondary lamellae epithelium (from extensive oedema to desquamation), hyperplasia of chloride cells, and breakdown of the pillar cell system. Muscle histology was also affected. Degeneration and disorganization of myofibrillar sarcomeric pattern as well as abnormal localization of mitochondria within muscle and altered endomysial sheaths were observed. Morphological alterations of spermatozoa within the gonadal tissue were also noticed. This study demonstrated that uranium exposure induced a variety of histological impairments in fish, supporting environmental concerns when uranium contaminates aquatic systems.

Chelation therapy and vanadium: effect on reproductive organs in rats.

Present investigation was planned to evaluate the therapeutic effectiveness of chelating agents against vanadium intoxication on blood and reproductive organs of rats. Male and female albino rats were injected vanadyl sulphate (7.5 mg/kg, po, for 21 days, 5 days in a week). Chelating agents tiron (T) alone and in combination with lipoic acid (LA), vitamin E (vit E) and selenium (Se) were given for 2 days/week. With the administration of vanadyl sulphate to rats fructose level in seminal vesicles was significantly (P< or =0.05) declined. The activities of alkaline phosphatase and adenosine triphosphatase were also decreased, whereas glycogen content and acid phosphatase activity increased in testis, seminal vesicles, ovaries and uterus after toxicant exposure. Significant changes in serum transaminases, serum alkaline phosphatase and lactate dehydrogenase were recouped by chelation therapy. Lipid peroxidation, reduced glutathione level and triglycerides levels altered significantly after exposure to vanadium in rats. The ultrastructural damage in spermatogenic stages in treated animals showed recovery pattern after therapy. Co-treatment with antioxidants restored these activities. The most effective combination was tiron + selenium followed by tiron + vitamin E, and tiron + lipoic acid.

Permanent and functional male-to-female sex reversal in d-rR strain medaka (Oryzias latipes) following egg microinjection of o,p'-DDT.

Complete sex reversal of fish is accomplished routinely in aquaculture practices by exposing fish to exogenous sex steroids during gonadal differentiation. A variety of environmental chemicals are also active at sex steroid receptors and theoretically possess the potential to alter normal sexual differentiation in fish. However, in controlled environmental chemical exposures to date, only partial alterations of fish sexual phenotype have been observed. Here we report complete, permanent, and functional male-to-female sex reversal in the Japanese medaka (Oryzias latipes, d-rR strain) after a onetime embryonic exposure to the xenoestrogen o, p'-DDT. d-rR strain medaka are strict gonochorists that possesses both sex-linked pigmentation, which distinguishes genotypic sex, and sexually dimorphic external secondary sexual characteristics, which distinguish phenotypic sex. We directly microinjected the xenoestrogen o, p'-DDT into the egg yolks of medaka at fertilization to parallel the maternal transfer of lipophilic contaminants to the embryo. At 10 weeks of age, microinjected medaka were examined for mortality and sex reversal. A calculated embryonic dose of 511 +/- 22 ng/egg o, p'-DDT (mean +/- standard error) resulted in 50% mortality. An embryonic exposure of 227 +/- 22 ng/egg o, p'-DDT resulted in 86% (6 of 7) sex reversal of genetic males to a female phenotype (XY females). XY females were distinguished by sex-linked male pigmentation accompanying female secondary sexual characteristics. Histologic examination of the gonads confirmed active ovaries in 100% of the XY females. In 10-day breeding trials in which XY females were paired with normal XY males, 50% of the XY females produced fertilized embryos; this represents a comparable breeding success rate to normal XX females. Fertilized eggs produced from XY females hatched to viable larvae. These results clearly indicate that a weakly estrogenic pesticide, o, p'-DDT, when presented during the critical period of gonadal development, can profoundly alter sexual differentiation.

Salmonid sexual development is not consistently altered by embryonic exposure to endocrine-active chemicals.

Fish sexual development is sensitive to exogenous hormone manipulation, and salmonids have been used extensively as environmental sentinels and models for biomedical research. We simulated maternal transfer of contaminants by microinjecting rainbow trout (Oncorhynchus mykiss) and chinook salmon (Oncorhynchus tshawytscha) embryos. Fish were reared for 6 months and sexed, and gonads were removed for histology and measurement of in vitro steroid production. Analysis of fat samples showed that dichlorodiphenylethylene (DDE) levels, o, p'M-DDE and p,o, p'-DDE isomers, were elevated 6 months after treatment. A preliminary study showed an increased ratio of males to females after treatment with 80 mg/kg and 160 mg/kg of the xenoestrogen o,o, p'-DDE. One fish treated with 160 mg/kg o,o, p'-DDE had gonads with cells typical of both males and females. A follow-up study, using more fish and excluding the highly toxic 160 mg/kg o,o, p'-DDE dose, showed no effect on sex ratio or gonadal histology. Embryonic exposure of monosex male trout, monosex female trout, and mixed sex salmon to o, o, p'-DDE, p,o, p'-DDE, mixtures of DDE isomers, and octylphenol failed to alter sexual development. We observed no treatment-dependent changes in in vitro gonadal steroid production in any experiments. Trout exposed in ovo and reared to maturity spawned successfully. These results suggest that mortality attributable to the xenoestrogens o,o, p'-DDE, chlordecone, and octylphenol, and the antiandrogen p,o, p'-DDE, is likely to occur before the appearance of subtle changes in sexual development. Because trout appeared to be sensitive to endocrine disruption, we cannot dismiss the threat of heavily contaminated sites or complex mixtures to normal sexual development of salmonids or other aquatic organisms.

Differential expression of type 2 and type 3 inositol 1,4,5-trisphosphate receptor mRNAs in various mouse tissues: in situ hybridization study.

The inositol 1,4,5-trisphosphate receptor (IP3R) is an intracellular Ca2+ release channel responsible for mobilizing stored Ca2+. Three different receptor types have been molecularly cloned, and their genes have been classified into a family. The gene for the type 1 receptor (IP3R1) is predominantly expressed in cerebellar Purkinje neurons, but its gene product is localized widely in a variety of tissues; however, there is little information on what types of cells express the other two receptor types, type 2 and type 3 (IP3R2 and IP3R3, respectively). We studied the expression of the IP3R gene family in various mouse tissues by in situ hybridization histochemistry. Compared with IP3R1, the levels of expression of IP3R2 and IP3R3 mRNAs were low in all of the tissues tested. IP3R2 mRNA was localized in the intralobular duct cells of the submandibular gland, the urinary tubule cells of the kidney, the epithelial cells of epididymal ducts and the follicular granulosa cells of the ovary, while the IP3R3 mRNA was distributed in gastric cells, salivary and pancreatic acinar cells and the epithelium of the small intestine. All of these cells which express either IP3R2 or IP3R3 mRNA are known to have a secretory function in which IP3/Ca2+ signalling has been shown to be involved, and thus either IP3R2 or IP3R3 may be a prerequisite to secretion in these cells.

Respiration of mitochondria from the gonads of the sea urchin, Strongylocentrotus droebachiensis: the effects of petroleum fractions on oxygen consumption.

The respiration of mitochondria from gonads of Strongylocentrotus droebachiensis has been studied in the presence of 2-oxoglutarate, glutamate and succinate. The rate of oxygen consumption increased with temperature between 4 and 20 degrees C. Removal of gametes from ripe gonads was necessary to obtain good respiring mitochondria. Equilibration of respiration media with various petroleum fractions reduced the rate of oxygen consumption and the coupling of O2 consumption to ADP utilization. Lighter fractions (leaded gasolines, unleaded gasoline and related fractions) were more deleterious than medium fractions (kerosene and fuel oil). Heavy fraction (bunker C, vacuum bottoms and crude oil) were least deleterious. Tetraethyl lead contributed to the toxicity of the leaded fractions.