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1.
Early and late developmental stages of grass shrimp embryos were exposed to different concentrations of two genotoxicants, 2-methyl-1,4-naphthoquinone (MNQ) and 4-nitroquinoline-N-oxide (NQO). DNA strand breaks were assessed by the comet assay while embryo development effects were determined by % of embryos hatching. Early embryo stage embryos were significantly more sensitive to genotoxicants than late stages. For example, all stage 4 embryos failed to hatch at 1 microM NQO while 95% of stage 8 hatched at this concentration. High DNA tail moments, which are a measure of the number of DNA strand breaks, were found in late stage embryos exposed to genotoxicants. Early stage embryo development was effected by low concentrations of genotoxicants but no changes were observed in DNA tail moments. We suggest that high DNA moments in late embryo stages reflect high DNA repair activity, while early stages may lack a fully developed DNA repair system.  相似文献   

2.
Grass shrimp embryos develop in egg sacs (stages 1-10) attached to the female for 14-20 days after which they 'hatch' from the egg sacs into a swimming zoea stage (stage 11). Until they emerge from the egg sacs, embryos depend on lipids and lipovitellin stored within the egg. The percent of embryos which hatch after exposure to toxicants relative to controls was the basis of an embryo development assay. Exposure of embryos to chromium(III) chloride, sodium chromate, mercuric chloride, and 2-methyl-1,2-naphthoquinone (MNQ) resulted in a reduced hatching rate. In addition to effects on embryo development, DNA strand damage tests were carried out on contaminant-exposed embryos, using the single-cell electrophoresis method often referred to as comet assay. Development of stage 4 embryos was more affected by MNQ exposure than stage 7 embryos. The hatching rates of stages 4 and 7 embryos exposed to MNQ (172 micrograms/l) were 0 and 90%, respectively. DNA strand damage, measured as DNA tail moments, were 3.4 and 4.4, respectively. Thus, exposure of an early embryo stage to MNQ prevented full embryo development while development of later embryo stages was not affected. It may be that the DNA repair systems are more efficient in later embryo stages than in early stages and thus DNA damaged in the early stages affects development.  相似文献   

3.
Exposure of grass shrimp (Palaemonetes pugio) embryos to four compounds (anthracene, pyrene, alpha-terthienyl, methylene blue) along with solar exposure resulted in extensive DNA strand damage using the comet assay. DNA tail moments of embryos exposed to these chemicals in the dark ranged from 1.8 to 4.3, while exposure to chemicals and solar resulted in tail moments of 14.3-15.3. Reduction of DNA tail moments when solar exposed embryos were transferred to the dark, suggested DNA repair systems were active. The comet assay can be used to follow both DNA damage and repair following exposure to phototoxic chemicals.  相似文献   

4.
Embryo production was reduced in female grass shrimp exposed to sediments with added coal fly ash and to sediments collected from an estuarine station containing high PAH concentrations due to its proximity to a highway storm drain. Grass shrimp embryos exposed to pore water from the high PAH and high metal sediments showed both reduced hatching and increases in DNA strand breaks (comet assay). Sediments with added coal fly ash had high concentrations of vanadium and selenium which may have contributed to effects similar to those observed with sediments with high PAH. The embryo pore water bioassay (hatching/DNA strand breaks) gave results comparable to those observed for reproduction effects (reduced embryo production/embryo hatching) with female grass shrimp exposed to whole sediment.  相似文献   

5.
A grass shrimp bioassay was carried out on sediments from three estuarine stations which were different distances from a highway storm drain. Total polycyclic aromatic hydrocarbon (PAH) concentrations were 29, 1.5 and 0.1 μg/g sediment at stations A (next to drain), B (100 m from drain) and C (500 m from drain), respectively. Lower embryo production and embryo hatching rates and a higher level of DNA strand breaks (comet assay) were observed in grass shrimp exposed to stations A and B sediments. There appeared to be an association between reproduction abnormalities and increased DNA strand breaks as a result of grass shrimp exposure to estuarine sediments receiving highway runoff.  相似文献   

6.
Oocytes (90 μm in diameter) were isolated from ovaries of 14-day post-molt adult female crabs and maintained in culture media. The addition of cadmium (20 μg/ liter) or tributyltin (2 μg/liter) to developing oocytes resulted in decreases in the growth of oocytes as measured by protein and lipovitellin accumulation relative to controls. Crab embryos isolated from yellow ‘sponge’ of female blue crabs were maintained in seawater until hatching (6–8 days). Toxicants tested included cadmium, copper, tributyltin and endosulfan. Some of the processes or events which were followed included water uptake, lipovitellin utilization rate, formation of appendages, formation of a heart, formation of eyespots and hatching to zoea stage. The primary effects from addition of toxicants were deformed eyespots and reduced hatching success. The hatching EC50 (concentration at which 50% of embryos failed to hatch) for copper, cadmium, tributyltin and endosulfan were 3.1, 0.25, 0.047 and 450 μg/liter, respectively. Crab embryos appear to be suitable for testing of the effects of a variety of toxicants with advantages including low cost, reproducibility, low variability and sensitivity.  相似文献   

7.
Anoxia-induced DNA damage in the gill cells of the marine scallop Mizuhopecten yessoensis was assessed with the alkaline comet assay (single-cell gel electrophoresis). The alkaline comet assay method for detecting DNA strand breaks and alkali labile sites in individual cells. DNA damage was determened in the scallops (M. yessoensis) gill cells. The scallops were exposed to air for 8 h showing a clear increase in the levels of DNA damage. After the air exposure, M. yessoensis were re-submersed for a period of 12 h, leading values to return to a pre-aerial exposure level. Control animals were kept immersed during the whole period. The resulting data demonstrate that natural influences, such as oxygen depletion (anoxia) in seawater, can be responsible for the induction of DNA damage. If the scallops were re-immersed in oxic conditions, the anoxically induced breaks were repaired. The main mechanisms influencing the integrity of the DNA structure are discussed in this paper.  相似文献   

8.
Previous experiments demonstrated that exposure of mummichog to cadmium (Cd) in combination with benzo[a]pyrene (BaP) caused a higher mortality than would be expected from simple additive effects. Experiments are described here that investigated whether BaP exposure inhibits the induction of metallothionein (MT), a major detoxifying protein for Cd, or if reactive BaP metabolites compete with Cd for binding sites on MT. Fish were injected with or without BaP (18 mg/kg) in combination with a low (1 mg/kg) or high (3.2 mg/kg) dose of Cd, and in one treatment BP was dosed 4 days after Cd. The results showed a rapid induction of MT to 1.5 mg/g wet weight liver, 1 day after injecting the low Cd dose. Simultaneous BaP exposure significantly delayed the induction of MT, for both low and high Cd doses, and BaP temporarily lowered the induced MT concentration when dosed 4 days after induction by Cd. To test if binding of BaP metabolites to MT reduces the detoxification potential for Cd, microsomes of CYP1A-induced fish were incubated with MT and radiolabeled BaP. Active metabolism of BaP was observed by high-performance liquid chromatography analysis, but no association of BaP metabolites with MT was found. Neither could this be demonstrated in vivo, in liver MT isolated from mummichog dosed with 3H-BaP and Cd. These results suggest that increased toxicity of Cd in combination with BaP exposure is likely to be caused by inhibited MT synthesis, rather than by interference of BaP metabolites with Cd binding on MT.  相似文献   

9.
Interactions between cadmium and sulfhydryl-containing compounds in striped mullet, Mugil cephalus, were examined. Exposure to 10 mg Cd/liter for up to 6 weeks caused an increase in the acid-soluble thiol (AST) content of the liver. Although the AST concentration was elevated at 1·4 weeks, increases in the glutathione and cysteine contents were not observed until after 4 weeks of exposure. Homogenates of livers were fractionated on a Sephadex G-75 column. A homogenate of livers of mullet injected with 109Cd 2 days prior to sampling had an elution profile for thiols similar to controls. After 3 weeks exposure to 10 mg Cd/liter the 9400 MW thiol peak increased 3·6-fold and the peak with the same retention volume as glutathione increased 4·3-fold. Greater than 70% of the thiols in these two peaks were acid-soluble. In both experiments, almost all the cadmium was associated with the 9400 MW peak. The ratio in the 9400 MW peak declined from 14·1 (controls) to 3·2 after 3 weeks exposure. No cadmium was associated with glutathione in the bile.  相似文献   

10.
1Introduction Afossorialmodeoflifehasbeenadoptedbynu merousfishes(Gibson,1982).Burrowingmodeof lifeclearlyoffersanumberofadvantages,butburro wingfishmustalsobeadaptedtocopewiththespe cialproblemsthatthislifestylepresents.Fishthat constructburrowsininterti…  相似文献   

11.
Levels of polycyclic aromatic hydrocarbons (PAHs) including benzo[a]pyrene (B[a]P) were at least seven-fold higher in mussels sampled from a polluted site (Loch Leven, in Scotland, UK) compared to a nearby clean reference site (Loch Etive) throughout the year 2000. Levels of DNA strand breaks (alkaline COMET assay) using both gill and digestive gland nuclei were similar at both sites despite the difference in contaminant load (total PAH). In contrast, mussels collected from a reference site (Port Quin, Cornwall, UK) had an increase in DNA strand breaks in digestive gland cells following laboratory exposure to B[a]P-dosed Isochrysis galbana. However, after 14 days high dose (20 ppb-exposed diet) animals had returned to levels similar to the controls. There was no evidence of increased necrosis or apoptosis after treatments. The results from these two studies suggest that an adaptive response may prevent ongoing DNA damage in mussels exposed to high levels of B[a]P and PAH contamination.  相似文献   

12.
DNA single-strand breaks were measured by the comet assay in both gill and hemolymph cells of mussels collected in 3 sampling areas of the French coast (Pointe du Castelli, Pen Bron and Saint-Nazaire Harbour). Whole mussel tissue samples were also collected for the chemical determination of PAH, PCB and heavy metal concentrations. In mussel, a higher level of DNA strand breaks was measured in gill than in hemolymph cells (p < 0.01). Despite a factor of contamination from 2 to 3 between sites, no difference in the extent of mussel DNA strand breaks was shown between sampling locations (p > 0.05), questioning the sensitivity of the assays used in biomonitoring studies.  相似文献   

13.
DNA single-strand breaks were analysed in the blue mussel (Mytilus edulis L.) deployed in intertidal and subtidal zones in the PAH contaminated Reykjavík harbour and at a reference site, Hvalfj?rethur, Iceland. DNA strand breaks were analysed by Comet assay in isolated gill and haemocyte cells from six mussels from each site and depth. Increased DNA damage in both gill cells and haemocytes were observed in mussels deployed in Reykjavík harbour compared to the reference site. Intertidal mussels from Reykjavík harbour had higher DNA damage in haemocytes compared to subtidal mussels. The Comet assay seems to be useful for measuring genotoxic exposure in mussels from the field, and that DNA damage might be higher in the intertidal zone either due to higher exposure to contaminants or because of physiological and biochemical responses to variations in oxygen availability.  相似文献   

14.
The zoeas of the estuarine terrestrial crab Sesarma haematocheir hatch in synchrony with nocturnal high tides. Hatching is also highly synchronized among embryos: i.e., female-attached embryos would all hatch within 1 h, if the female is maintained at about 23°C. This study examined the factors affecting the timing of hatching in female-attached and detached embryos. The timing of hatching in the embryos detached from the female was somewhat affected by continuous light, salinity, and cluster size, but it was much more strongly affected by low temperature. In addition, a notable feature was that the influence of low temperature was markedly different between female-attached embryos and detached embryos. Hatching of this crab occurs after a special developmental process for hatching ("hatching program") that requires 48–49.5 h. This program would be mediated by a temperature-dependent process. Hatching of this crab cannot be fully explained in terms of osmotic effects. Since hatching of female-attached embryos was highly synchronized, the female should release an (unknown) stimulus enhancing hatching synchrony among embryos. Highly synchronized hatching among embryos would enable the female to release hatched zoeas into the water all at one time.  相似文献   

15.
The alkaline comet assay was tested on different microalgae: the dinoflagellates, Karenia mikimotoi and Alexandrium minutum, and the diatom, Chaetoceros gracilis. The microalgae were exposed during their exponential growth to the model direct genotoxicant, hydrogen peroxide (1h, 5 and 100muM H2O2). Following H2O2 exposure, the comet assay was validated only for K. mikimotoi for which genotoxicity was observed from the lowest tested concentration of 5 microM with a concentration-dependent effect. C. gracilis was too small in size (4 microm) to be correctly analysed. For A. minutum, our lysis buffer was not strong enough to digest the cellulosic thecal plates. For K. mikimotoi, the comet assay was thus applied for the study of the genotoxic effects of different pesticides: epoxiconazole (as Opus formulation), chlorpyriphos-ethyl (as Dursban formulation) and endosulfan at 1, 10 and 100 microg of active substance/L for 24h. Exposure to epoxiconazole in formulation resulted in an increase in the extent of DNA strand breaks at the highest tested concentration icro/L. Endosulfan exposure resulted in DNA damage for K. mikimotoi nuclei. Genotoxicity was observed from 1 microg/L of endosulfan and was not concentration dependent.  相似文献   

16.
The impact of dietary and water exposure on the accumulation and distribution of cadmium (Cd) in subcellular components of the polychaete Capitella sp. I was investigated. Worms were exposed to either dissolved Cd alone ('Water-Only' treatments; WO) or diet-bound Cd alone ('Algae-bound Only' treatments; AO). Thus, WO worms were starved and AO worms were fed. Differential centrifugation was used to fractionate worm homogenates into debris- (DE), mitochondrial- (MI), microsomal- (MC) and cytosolic- (CY) fractions, and the concentration of Cd in these fractions was quantified by radiometric analysis using the specific activity of the (109)Cd radioisotope. Neither exposure route nor Cd exposure affected the total protein content in the worms. However, fed, but not starved worms relocated proteins from the mitochondria to the cytosol in response to Cd exposure. In systems without Cd addition, starvation likewise influenced the distribution of protein between mitochondria and cytosol. Cutaneous uptake and accumulation of Cd from the water was related to surface area while dietary uptake was influenced by the amount of sediment passing through the gut. Irrespective of exposure route, Cd was accumulated primarily in the debris fraction although comparisons between the treatments indicated that relatively less Cd was located in DE and more in MI, MC and CY fractions in worms in AO compared to worms in WO. Cd per unit protein in DE and MI fractions was twice as high as in MC and CY fractions in WO, whereas MC contained the highest Cd content followed by MI, DE and CY fractions in AO worms. Our results stress the importance of exposure route for the internal distribution and toxicity of Cd to deposit feeders such as Capitella sp. I.  相似文献   

17.
There is a growing body of evidence to suggest that certain polycyclic aromatic hydrocarbons (PAHs) pose a greater hazard to aquatic organisms than previously demonstrated, due to their potential to cause photo-induced toxicity when exposed to ultraviolet (UV) radiation. The consequences of photo-induced toxicity are reported here for embryo-larval stages of the pacific oyster Crassostrea gigas, following exposure to pyrene and benzo[a]pyrene. During laboratory investigations, significant increases in toxicity were observed in the presence of environmentally attainable levels of UV-radiation, compared with embryos exposed to PAH alone, at levels previously deemed to have little acute biological effect. The phototoxicity of pyrene and benzo[a]pyrene completely inhibited the development to the D-shell larval stage when embryos were simultaneously exposed to 5 microg l(-1) PAH and ultraviolet light (UVB = 6.3 +/- 0.1 microW/cm2 and UVA = 456.2 +/- 55 microW/cm2). A linear relationship was also demonstrated for benzo[a]pyrene phototoxicity with decreasing UV light intensity.  相似文献   

18.
Liver catalase activity was used as an index of cadmium poisoning in the killifish, Fundulus heteroclitus, and was found to be inhibited following both in vivo and in vitro exposure to dissolved cadmium at a concentration greater than 1 mg/litre. Pre-exposure at 1 mg Cd/litre prevented catalase inhibition at higher subsequent doses of cadmium. Comparison of the effects of in vivo and in vitro exposure showed in vivo exposure to cadmium to result in greater catalase inhibition.Cadmium and copper binding was determined by gel chromatography and found to occur at three distinct liver cytosol fraction peaks. Both metals showed enhanced cytosol concentrations with cadmium exposure and relative changes in peak levels as related to cadmium exposure regimes. Cadmium thionein (molecular weight of 7–10,000) was found in the killifish liver and was correlated with adaptive responses in liver catalase activity. High molecular weight cadmium binding was found to be a better index of cadmium toxicity to liver catalase than total liver cadmium concentration.  相似文献   

19.
The use of selected hematological and biochemical parameters as indicators of metal exposure in aquatic organisms was evaluated. The hematological and biochemical parameters examined include glucose, hematocrit and aminotransferase levels in golden shiners exposed to cadmium. Cadmium exposure produced significant alterations in the levels of glucose, aspartate aminotransferase and alanine aminotransferase; however, hematocrit was not altered by exposure to cadmium. In addition, the comparative activity of Na/K adenosine triphosphatase (ATPase) was evaluated in the fathead minnow, golden shiner and bluegill sunfish. Basal Na/K ATPase activity was lowest in golden shiner (1·01 μmol Pi/mg protein/h) and highest in bluegill sunfish (1·45 μmol Pi/mg protein/h). While a stimulation of Na/K ATPase activity was observed at an exposure concentration of 1 μg Cd/liter in the fathead minnow and bluegill sunfish, inhibition of enzymatic activity was observed at higher exposure concentrations (10 and 100 μg Cd/liter). Gill Na/K ATPase activity in golden shiner was not significantly influenced by cadmium exposure. The observed insensitivity of ATPase in shiner may, in part, be related to higher background and accumulated concentrations of cadmium in gill tissue.  相似文献   

20.
The synthesis of phytochelatins (PC), intracellular metal-binding polypeptides characterized by a repeating sequence of gamma-glutamic acid- cysteine (gamma-Glu-Cys) pairs, has been studied in laboratory cultures of the marine diatom Phaeodactylum tricornutum exposed to Cd, Pb or Zn. Cd and Pb were able to induce PC of different degree of polymerization. The accumulation of the peptides follows a direct relationship with the metal exposure. No PC induction was observed in Zn-treated cultures, although the intracellular concentration of Zn increased during exposure. Both in short-term (7 h exposure, 10 microM Cd or Pb) and 3-day experiments (metal concentration less than 0.5 microM), the major fraction of total PC gamma-Glu-Cys subunits synthesized was polymerized as PC2 when cells were exposed to Pb, but as PC4 when cells were exposed to Cd. In short-term experiments about 50% of the gamma-Glu-Cys residues of the cellular pool of glutathione was quickly and almost quantitatively converted into PC. Recovery experiments, in which metal-stressed cells are suspended in a metal-free medium, showed a decrease of the PC pool and a concomitant increase of glutathione, suggesting a mechanism of degradation and release of metal-phytochelatin complexes.  相似文献   

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