Bioaccumulation and metabolisation of (14)C-pyrene by the Pacific oyster Crassostrea gigas exposed via seawater.

The first objective of this study was to determine the bioaccumulation kinetics of pyrene in the soft tissues of Crassostrea gigas (mantle, muscle, gills, digestive gland, and the remaining soft tissues). As bivalves can biotransform hydrocarbons in more polar compounds (metabolites) that are more easily excreted, the second objective was to investigate the oyster capacity to metabolize pyrene into its metabolite, the 1-hydroxypyrene. To these ends, oysters were exposed 24 h to waterborne (14)C-pyrene then placed in depuration conditions for 15 d. Oysters efficiently bioaccumulated pyrene in their soft tissues and equilibrium was reached within the exposure time. The metabolite1-hydroxypyrene was also detected in oyster tissues but represented only 4-14% of the parent pyrene. At the end of the exposure period, the gills and the mantle showed the highest pyrene proportion of total soft tissue content, i.e. 47% and 26%, respectively. After 15 d of depuration, the mantle contained 32% and 30% of the remaining pyrene and 1-hydroxypyrene, respectively. As C. gigas did not display a high capacity for metabolizing pyrene, it can be considered as a good bioindicator species to survey and monitor pyrene contamination in the coastal marine environment.

Biokinetics of Hg and Pb accumulation in the encapsulated egg of the common cuttlefish Sepia officinalis: radiotracer experiments.

Uptake and depuration kinetics of dissolved (203)Hg and (210)Pb were determined during the entire embryonic development of the eggs of the cuttlefish, Sepia officinalis (50d at 17 degrees C). (203)Hg and (210)Pb were accumulated continuously by the eggs all along the development time reaching load/concentration ratio (LCR) of 467+/-43 and 1301+/-126g, respectively. During the first month, most of the (203)Hg and (210)Pb remained associated with the eggshell indicating that the latter acted as an efficient shield against metal penetration. From this time onwards, (203)Hg accumulated in the embryo, indicating that it passed through the eggshell, whereas (210)Pb did not cross the chorion during the whole exposure time. It also demonstrated that translocation of Hg associated with the inner layers of the eggshell is a significant source of exposure for the embryo. This study highlighted that the maturing embryo could be subjected to the toxic effects of Hg in the coastal waters where the embryonic development is taking place.

Trends in concentrations of selected metalloid and metals in two bivalves from the coral reefs in the SW lagoon of New Caledonia.

The concentrations of nine elements (Ag, As, Cd, Co, Cr, Cu, Mn, Ni and Zn) were measured in the oyster Isognomon isognomon and the edible clam Gafrarium tumidum from different sites along the SW New Caledonian coast which is subjected to important chemical inputs due to intense land-based mining activities (New Caledonia is the third world producer of nickel). Results indicate that concentrations in the two organisms mirrored the geographical differences in contamination levels as established through element analyses in sediment. On the basis of organism analyses, two out of the seven investigated stations can be considered as relative "reference" sites, except for As, for which very high levels were detected in clam and oyster tissues (up to 441 microg g(-1) dry wt for clams). Overall, our results indicate that both tropical organisms investigated could be used as valuable bioindicator species for surveying metal contamination in the coastal waters of New Caledonia with reasonable perspectives of wider application to other coral reef environments.

Bioaccumulation and detoxification processes of Hg in the king scallop Pecten maximus: field and laboratory investigations.

Hg bioaccumulation was investigated in the king scallop Pecten maximus in the laboratory and in the field. In controlled conditions, scallops were exposed to (203)Hg through seawater, sediment and food in order to determine its uptake and depuration kinetics. In the field, Hg and metallothionein (MT) concentrations and the metal subcellular distribution were determined in scallops from two sites of the Bay of Seine (France) differently subjected to the Seine river inputs. While Hg concentrations in the whole soft parts and kidneys (viz. the highest accumulator organ) did not differ between scallops from both sites (74-156 ng g(-1)dry wt), they did for the digestive gland and the gills. According to the experimental results, a higher exposure to dissolved Hg might occur in the site close to the estuary whereas Hg would be mainly incorporated via the dietary pathway in the site away from the estuary. Within the cells of wild scallops, Hg was mainly associated to the cytosolic fraction in the digestive gland and gills (60-100%). However, the lack of relationship between Hg and MT levels suggests that Hg detoxification in P. maximus involves other, non-MT, soluble compounds. In kidneys, insoluble compounds played an important role in Hg sequestration. No effect of scallop age was observed neither on Hg and MT concentrations nor on the subcellular distribution of the metal. Finally, according to FAO/WHO recommendations (maximum weekly Hg intake), our results clearly indicate that the low Hg contents in the edible part of the king scallops from the Bay of Seine prevent any risk for human consumers.

Differential bioaccumulation behaviour of Ag and Cd during the early development of the cuttlefish Sepia officinalis.

Cuttlefish eggs were exposed to background concentrations of dissolved Ag and Cd, using the radiotracers (110m)Ag and (109)Cd. At different time of the embryonic development (50 days), some eggs were placed in non-contaminating conditions. During the experiment, the uptake and depuration kinetics, and distribution of these metals among the egg compartments (i.e. eggshell, vitellus, peri-vitelline fluid and embryo) were assessed. In parallel, experiments were conducted with sub-lethal concentrations of stable Ag and Cd (2 and 1 microgl(-1), respectively) to compare the metal behaviour at higher concentrations. From the spawning date up to 1 month of development, both metals were taken up efficiently by the eggs, reaching load/concentration ratio (LCR) of 1059+/-75 and 239+/-22 for (110m)Ag and (109)Cd, respectively. From this time onwards, (110m)Ag activity continued to increase in eggs, whereas (109)Cd kinetics displayed a significant decrease. Whatever the developmental stage, Cd was mainly associated with the eggshell all along the exposure experiment. In addition, both stable Cd concentrations and (109)Cd LCR remained low in the embryo all along the embryonic development, indicating that the eggshell acted as an efficient shield against the penetration of this metal. In contrast, (110m)Ag passed through the eggshell from day 30 onwards and was then accumulated in the embryo, which contained more than 40% of the whole egg metal burden at the end of the exposure period. In depuration conditions, it is noteworthy that Ag continued to accumulate in the embryo indicating translocation processes from the eggshell and a high affinity of the metal for the embryo tissues. Overall our results showed that at day 30 of the embryonic development the cuttlefish eggshell becomes permeable to Ag but not to Cd. Exposure to stable metals confirmed the saturation capacities of the eggshell for Cd and the Ag penetration properties.

Accumulation of nine metals and one metalloid in the tropical scallop Comptopallium radula from coral reefs in New Caledonia.

Uptake of waterborne Cd, Co, Mn and Zn was determined in laboratory experiments using radiotracer techniques (109Cd, 57Co, 54Mn and 65Zn). Labelled Zn was mainly accumulated in the digestive gland (65%) and Co in kidneys (81%); Cd and Mn were similarly distributed in digestive gland and gills. In a complementary field study, Ag, As, Cd, Co, Cr, Cu, Fe, Mn, Ni, and Zn were analysed in scallops collected at two stations showing different contamination levels. Digestive gland and kidneys displayed the highest concentrations. Ag, As, Cd, and Fe differed in soft tissues from the two stations, suggesting that Comptopallium radula could be a valuable local biomonitor species for these elements. Low Mn and Zn concentrations found in kidneys suggest that their content in calcium-phosphate concretions differs from the other pectinids. Preliminary risk considerations suggest that As would be the only element potentially leading to exposure of concern for seafood consumers.

Nickel bioaccumulation in bivalves from the New Caledonia lagoon: seawater and food exposure.

The New Caledonian lagoon is submitted to intense heavy metal input from land-based Ni mining. Therefore, the use of sentinel species is strongly recommended in order to develop and implement coastal zone management programmes of the metal contamination. The tropical oysters Isognomon isognomon and Malleus regula and the clam Gafrarium tumidum were previously proposed as such possible sentinel organisms and were thus investigated in this context. The three species were exposed to Ni via seawater or food using radiotracer techniques. Results indicate that uptake and retention efficiencies of Ni are independent of the dissolved Ni concentrations in the surrounding seawater. Hence, for the three species, body concentrations of Ni taken up from the dissolved phase are directly proportional to the ambient dissolved concentrations. Biokinetic patterns indicated that the major part of Ni was rapidly lost from bivalves during the first days of depuration, whereas 7 to 47% of 63Ni were retained in tissues with a biological half-life not significantly different from infinity. Finally, feeding experiments showed that Ni ingested with food (phytoplankton) was assimilated more efficiently in clams (assimilation efficiency, AE = 61%) than in oysters (AE = 17%), and was strongly retained (T(b1/2) > or = 35 d) in the tissues of both bivalves. It is concluded that the investigated species examined are efficient bioaccumulators of Ni from both the surrounding seawater and the food, and that they would be useful bioindicators for monitoring the status of Ni contamination in tropical coastal waters.

Allometric relationships in the bioconcentration of heavy metals by the edible tropical clam Gafrarium tumidum.

Although metal contamination is a problem of major concern in the lagoon of New Caledonia due to intense mining activities conducted on land, very little is known on the metal ecotoxicology of local marine organisms. The clam Gafrarium tumidum was investigated to assess its usefulness as a bioindicator species of metal contamination in this lagoon. More particularly, allometric relationships between metal accumulation and clam size were determined for five common metals in New Caledonian lagoon waters (Cd, Cr, Co, Zn and Ag) using a highly sensitive radiotracer technique. Experimental results showed that allometric relationships were dependent on the element and on the body compartment considered. As a rule, allometric relationships of metal concentration factor were more pronounced in shell than in soft parts. Significant relationships with clam size for Cd, Cr, Co and Zn followed inverse power functions. In contrast, the degree of Ag bioaccumulation was positively correlated with size. In view of the literature on Ag in bivalves, the latter observation suggests the occurrence of a specific detoxification mechanism (sequestration) that would be more efficient in old individuals. Overall, the experimental results indicate that the use of G. tumidum as a bioindicator in monitoring programmes requires selecting individuals of a specific size range in order to obtain comparable information about ambient metal levels. Since the size effect is greatest among smaller individuals, it is recommended to select clams with a shell width greater than 35 mm.

Bioaccumulation and effects of PCBs and heavy metals in sea stars (Asterias rubens, L.) from the North Sea: a small scale perspective.

Sea stars (Asterias rubens L.) were collected in different stations distributed in the Southern Bight of the North Sea. Concentrations of four heavy metals and six PCB congeners were measured in two body compartments (body wall and pyloric caeca). In order to assess the potential harm of these contaminants, two biochemical parameters were measured in sea stars, viz. reactive oxygen species (ROS) production by amoebocytes and cytochrome P450 immunopositive protein (CYP1A IPP) induction in pyloric caeca. Sea stars from stations located in the plume of the Scheldt river showed the highest contamination levels. Other stations, similarly located, displayed lower levels. No simple relationship could be established between ROS production by sea star amoebocytes and contaminant levels measured in sea star tissues. CYP1A IPP induction displayed more contrasted responses, and highly significant regressions were found between PCB concentrations measured in pyloric caeca and CYP1A IPP. Both biological parameters were found to vary significantly over the study area. On the whole, data indicated that contamination levels and subsequent effects in sea stars were comparable to those described in previous large-scale studies, but that working at a smaller scale highlighted the existence of patterns of contamination which can blur general trends due to major contamination sources like contaminated rivers.

Bioaccumulation of PCBs in the sea urchin Paracentrotus lividus: seawater and food exposures to a 14C-radiolabelled congener (PCB#153).

Adult Paracentrotus lividus were exposed to a 14C-labelled PCB congener (PCB#153) using two different exposure modes: (1) the surrounding sea water and (2) the food (viz. the phanerogam Posidonia oceanica and the brown alga Taonia atomaria). Uptake kinetics from water and loss kinetics after single feeding were followed in four body compartments of the sea urchins (body wall, spines, gut and gonads). Results indicate that PCB bioaccumulation in P. lividus varies from one body compartment to another, with the exposure mode and the nature of the food. The echinoids accumulate PCB#153 more efficiently when exposed via water than via the food (the transfer efficiency is higher by one order of magnitude). Target body compartments of PCB#153 were found to be body wall and spines when individuals were exposed via water, and gut when they were exposed via food. It is concluded that P. lividus is an efficient bioaccumulator of PCB and that it could be considered as an interesting indicator for monitoring PCB contamination in the marine environment.

Bioaccumulation of PCBs in the cuttlefish Sepia officinalis from seawater, sediment and food pathways.

The cuttlefish Sepia officinalis was selected as a model cephalopod to study PCB bioaccumulation via seawater, sediments and food. Newly hatched, juvenile cuttlefish were exposed for 17 days to environmentally realistic concentrations of (14)C-labeled 2,2',4,4',5,5'-hexachlorobiphenyl (PCB#153) (18 ng PCB l(-1) seawater; 30 ng PCB g(-1) dry wt sediments; Artemia salina exposed to 18 ng PCB l(-1) seawater). Accumulation of PCB#153 was followed in three body compartments: digestive gland, cuttlebone and the combined remaining tissues. Results showed that (1) uptake kinetics were source- and body compartment-dependent, (2) for each body compartment, the accumulation was far greater when S. officinalis was exposed via seawater, (3) the cuttlebone accumulated little of the contaminant regardless of the source, and (4) the PCB congener showed a similar distribution pattern among the different body compartments following exposure to contaminated seawater, sediment or food with the lowest concentrations in the cuttlebone and the highest in the remaining tissues. The use of radiotracer techniques allowed delineating PCB kinetics in small whole organisms as well as in their separate tissues. The results underscore the enhanced ability of cephalopods to concentrate organic pollutants such as PCBs, and raise the question of potential risk to their predators in contaminated areas.

Measurement of EROD activity: caution on spectral properties of standards used.

The activity of the enzyme 7-ethoxy-resorufin- O-deethylase (EROD) has been extensively used in biomonitoring studies for more than a decade. Although the analytical procedure is simple, it is often poorly characterized. In this study spectral properties of particular standard compounds used to measure EROD activity (ethoxyresorufin and resorufin, standards from Molecular Probes) were tested in order to optimize excitation and emission wavelengths to be used in the fluorimetric assay of EROD activity. The optimal excitation wavelength for the detection of resorufin was 560 nm. At this wavelength the excitation represents only 37% of its maximum level for ethoxyresorufin, while it represents 86% for resorufin. This allows discrimination between the fluorescence emitted by both standards, favoring the formed resorufin. Our results demonstrate that any analytical work using spectrofluorometry to measure EROD activity should be preceded by precise determination of the spectral characteristics of each set of standards used.

Contaminant levels in sediments and asteroids (Asterias rubens L., Echinodermata) from the Belgian coast and Scheldt estuary: polychlorinated biphenyls and heavy metals.

The Southern Bight of the North Sea is particularly exposed to anthropogenic contamination, due to heavy urbanisation and industrialisation of its catchment area. The present work focuses on polychlorinated biphenyl (PCB) and metal contamination of the marine environment along and off the Belgian coast. Its objectives were to compare the concentrations of seven PCB congeners and four heavy metals in the sediments (a repository for anthropogenic contaminants) and in the asteroid Asterias rubens (a recognized bioindicator species). Nineteen sampling stations were considered between the mouth of the Scheldt Estuary and the southern limit of the Belgian coast (asteroids were found in 10 out of the 19 stations). PCB and metal concentrations measured in sediments and asteroids were in the range of values reported in previous studies. Stations under direct influence of the Scheldt were the most impacted by the considered contaminants. Metal concentrations varied according to the grain-size fraction considered. In asteroids, PCBs and metals were found to be selectively distributed among body compartments, and pyloric caeca were found to most efficiently discriminate between sampling stations contamination levels. PCB and metal analysis of sediments provided a physicochemical evaluation of the contamination, whereas analysis of asteroids introduced a biological dimension to the approach by taking into account bioavailability of the contaminants.

Hormetic versus toxic effects of vegetable tannin in a multitest study.

Tannin from mimosa trees (Acacia sp.) utilized in traditional leather tanning was tested for toxicity in sea urchin (Sphaerechinus granularis and Paracentrotus lividus) embryos and sperm, marine, and freshwater algae (Selenastrum capricornutum and Dunaliella tertiolecta), and Daphnia magna. Based on a two-step tanning procedure used in traditional tanneries, two mimosa tannin preparations, i.e., fresh tannin (FT) and used tannin (UT), were tested as suspensions. The early results in S. granularis embryos showed that UT exerted lower acute toxicity than FT, namely, 1 vs 100 mg/L, to obtain 100% mortality, respectively. Subsequent bioassays were conducted on fresh tannin water extracts (TWE) corresponding to nominal tannin concentrations ranging from 0.1 to 30 mg/L. Developmental toxicity, up to embryonic mortality was exerted by TWE at levels > 1 mg/L, S. granularis being more sensitive than P. lividus embryos/larvae. At the concentration of 0.1 mg/L, the frequencies of larval malformations were significantly lower than in controls. This positive stimulatory effect (currently termed as hormesis) was observed in extended numbers of culture replicates (up to 14) and was significant in the embryo cultures characterized by a relatively poor control quality (with < 70% viable larvae in controls), whereas this effect was not observed in good-quality cultures (with > or = 70% viable larvae in controls). Cytogenetic analysis of S. granularis embryos reared in FT or UT suspensions (1 mg/L to 1 g/L) showed mitotoxic effects (decrease in active mitoses per embryo) in FT-exposed, but not in UT-exposed embryos. Mitotic aberrations were significantly increased by 10 mg/L UT. Sperm fertilization success in both sea urchin species showed an increasing fertilization rate (FR) up to 0.3 mg/L TWE and a dose-related decrease in FR up to 30 mg/L. Again, the offspring of P. lividus sperm exposed to TWE (0.1 and 0.3 mg/L) showed a decrease in larval malformations compared to controls, whereas a dose-related increase in developmental defects was observed in the offspring of P. lividus sperm exposed to higher TWE levels (1 to 30 mg/L). Algal cell growth bioassays in two species (S. capricornutum and D. tertiolecta) also showed a maximum growth at TWE levels ranging from 0.3 to 3 mg/L and a subsequent decline up to 30 mg/L TWE. D. magna bioassays resulted in daphnid immobilization by TWE concentrations ranging from 100 to 300 mg/L. The results demonstrate that tannins utilized in traditional leather tanning industry may raise concern of environmental damage at relatively high concentrations, whereas low-level tannins may result in hormetic effects. The present study also points to the need for bioassay design that should rely on adequate criteria in control quality, allowing to detect both inhibitory and hormetic effects.

Echinoderms as bioindicators, bioassays, and impact assessment tools of sediment-associated metals and PCBs in the North Sea.

The study assessed the occurrence, possible toxicity, and impact of sediment-associated metals and PCBs in the coastal zone of the southern North Sea using echinoderms as representatives of the macrobenthos. Metals and PCBs were analyzed in the sediments and in the body compartments of the starfish Asterias rubens from 11 stations. The general toxicity of sediment-associated contaminants was assessed by bioassays using embryonic and larval developments of both A. rubens and the sea urchin Psammechinus miliaris. The impact of contamination was assessed by measuring cellular immune responses of A. rubens collected in the same stations. Contamination of the starfish by metals and PCBs closely reflected that of the sediments. However, bioaccumulation was element-specific for metals and depended on the chlorination pattern for PCBs. The sediment-associated contaminants appeared to be toxic in both the A. rubens and P. miliaris developmental assays. Moreover, metals were shown to affect the immune responses of starfishes living in contaminated stations. The most significant effects on biological responses were recorded in the plumes of the Scheldt/Rhine/North Sea Canal and the Elbe/Weser Rivers.

Factors affecting R6 fungicide toxicity on sea urchin fertilization and early development: roles of exposure routes and mixture components.

A technical fungicide mixture, R6 and its components, cymoxanil (CYM) and cupric oxychloride (Cu-OCl), were tested by sea urchin bioassays (Paracentrotus lividus and Sphaerechinus granularis). A set of toxicity endpoints was evaluated including both lethal and sublethal effects with the following endpoints: (a) acute embryotoxicity, (b) developmental defects, (c) changes in sperm fertilization success, (d) transmissible damage from sperm to the offspring, and (e) cytogenetic abnormalities. Acute effects on developing embryos were observed as early (prehatch) mortality at R6 levels > or =25 microg/ml. The pesticide mixture R6 was tested at realistic concentrations, ranging from 25 ng/ ml to 2.5 microg/ml, and the two components, CYM and Cu-OCl, were tested, either alone or in mixture, at concentrations equal to their levels in the corresponding R6 solutions. R6 was either dissolved in filtered seawater (water only, W-O), or spiked in "pristine" silt-clay sediment or soil samples before bioassays. Developmental toxicity of R6, following W-O dissolution, displayed a significant dose-related increase of larval malformations and differentiation arrest at concentrations of 750 ng/ml to 2.5 microg/ml both in P. lividus and in S. granularis larvae. Developmental toxicity was removed in spiked sediment up to R6 nominal levels (25 microg/ml), 10-fold above the embryotoxic R6 levels in W-O exposure. No significant developmental toxicity was exerted by CYM or Cu-OCl (W-O exposure) up to their concentrations equivalent to 2.5 microg/ml R6. The laboratory-prepared mixture of CYM and Cu-OCl, in the same concentration range, only resulted in minor effects, as larval retardation, suggesting the presence of toxic impurities (or additional components) in the R6 formulation. When sperm from either P. lividus or S. granularis were exposed to R6 before fertilization, a W-O exposure resulted in a dose-related decrease in fertilization of P. lividus sperm (up to 250 microg/ml R6), whereas S. granularis sperm underwent a significant increase of fertilization rate at the highest R6 nominal levels (up to 25 microg/ml). Equivalent CYM or Cu-OCl levels were ineffective on sperm fertilization success in both species. The offspring of S. granularis sperm exposed to 25 microg/ml R6 showed a significant increase in larval malformations, which were not detected in the offspring of R6-exposed P. lividus sperm. Again, CYM or Cu-OCl was unable to exert any transmissible damage from sperm to the offspring in either species. The present study raises the case of possible discrepancies between toxicity of a technical mixture and of its analytical-grade components, also providing evidence for a loss of pesticide toxicity following dispersion in an environmental matrix such as sediment or soil.

Effects of PCBs on reactive oxygen species (ROS) production by the immune cells of Paracentrotus lividus (Echinodermata).

The impact of four PCB congeners: 3,3',4,4'-tetrachlorobiphenyl (IUPAC congener #77), 3,3',4,4',5-pentachlorobiphenyl (IUPAC #126), 2,2',4,4',5,5'-hexachlorobiphenyl (IUPAC #153) and 3,3',4,4',5,5'-hexachlorobiphenyl (IUPAC #169) was investigated on the reactive oxygen species (ROS) production by coelomocytes of the echinoid Paracentrotus lividus, an important species in marine benthic ecosystems. PCBs were found to increase ROS production and to delay the time of peak production. These effects were stronger on bacteria-stimulated cells and were congener-specific: coplanar congeners (#77, 126 and 169) had more effect than the non-coplanar PCB #153. Among coplanar congeners, PCB #169 showed dose-dependent effects whereas PCB #77 and 126 were more toxic at high and low doses, respectively. The relative immunotoxicity of the different PCB congeners is discussed in the light of their structural properties and biological affinities.

The role of oxidative stress in developmental and reproductive toxicity of tamoxifen.

The antiestrogen tamoxifen (TAM) is widely used as a drug against breast cancer and is currently being tested as a chemopreventive agent. However, a number of studies showed genotoxic and carcinogenic effects of TAM. These effects are thought to be related to oxygen radical overproduction which occurs during TAM metabolic activation. There is no evidence, thus far, on TAM toxicity to embryos and gametes. The present study was designed to elucidate the mechanisms of TAM-induced developmental, reproductive and cytogenetic toxicity towards sea urchin (SU) embryos with regard to the possibility of TAM-initiated oxidative stress. Embryo cultures from SU were subjected to long-term (throughout embryogenesis) or short-term (two hours) incubation with TAM at concentrations from 10(-8) to 10(-5) M. The experiments on TAM-induced toxicity to gametes were carried out with SU sperm, or unfertilized eggs, suspended in TAM (10(-8) to 10(-6) M). To assess the effects of TAM to embryos or to gametes, developmental defects, embryonic mortality, fertilization success, and cytogenetic abnormalities were scored. Oxidative damage to DNA and lipids was detected by measurements of 8OHdG levels and lipid peroxidation, respectively. Reactive oxygen species (ROS) production by eggs and embryos was recorded by luminol-dependent chemiluminescence (LDCL) and cytochrome c reduction methods. The changes in activities of SU superoxide dismutase (SOD) and catalase were also evaluated. TAM exerted: a) early embryonic mortality to exposed embryos and to the offspring of exposed eggs; b) developmental defects to the offspring of exposed sperm; c) decrease in sperm fertilization success, and d) cytogenetic effects in the offspring of exposed sperm or eggs. These morphological effects corresponded to the state of oxidative stress in SU embryos (increased oxidative damage to DNA and lipids and induction of antioxidant enzymes). Since TAM did increase significantly ROS production by embryos, it is suggested that TAM may be metabolically activated by SU embryonic oxidases and peroxidases, which in turn could be induced by TAM. The present study provides further support to the utilization of the SU system as a useful model to help elucidate mechanisms of chemical teratogenesis and carcinogenesis.

Diepoxybutane and mitomycin C toxicity is associated with the induction of oxidative DNA damage in sea urchin embryos.

Diepoxybutane (DEB)- and mitomycin C (MMC)-associated toxicity was investigated in embryos from the sea urchin (SU) species Sphaerechinus granularis. DEB- and MMC-induced toxicity resulted in S. granularis embryos and larvae at concentrations ranging 10(-5) to 10(-4) M DEB, and 3 x 10(-6) to 3 x 10(-5) M MMC, in terms of larval malformations, developmental arrest and mortality. The formation of DNA oxidative damage, 8-hydroxy-2'-deoxyguanosine (8-OHdG) was measured in DEB- and in MMC-exposed embryos (at gastrula stage). A dose-dependent increase in 8-OHdG levels was observed that was significantly correlated with DEB- and MMC-induced developmental defects. The results lend further support to the body of evidence associating both DEB and MMC toxicity with oxidative stress, including DNA oxidative damage.