Víctor J. Moreno

Genotoxic evaluation of the pyrethroid lambda-cyhalothrin using the micronucleus test in erythrocytes of the fish Cheirodon interruptus interruptus

In order to develop experimental models able to detect genotoxic effects of pollutants in aquatic organisms, the genotoxicity of the pyrethroid lambda-cyhalothrin was studied using the micronucleus test in erythrocytes of Cheirodon interruptus interruptus. The frequency of micronuclei was examined in blood smears obtained from fishes exposed in vivo to three different concentrations (0.05; 0. 01; 0.001 ug/l) of the compound and sacrificed at nine sampling times (24, 48, 72, 96 h and 8, 12, 15, 19 and 23 days). As a positive control fishes were exposed to 5 mg/l of cyclophosphamide. Results obtained demonstrated the genotoxic effects of the pyrethroid in the experimental model employed. The variation in the micronuclei frequencies in the different sampling times could be related to the blood cell kinetics and the erythrocyte replacement. The results could be considered as a validation of the MN test in fishes for the assessment of genotoxic pollutants.

Heavy metals in Antarctic organisms

Abstract To evaluate levels of essential (zinc and copper) and non-essential (mercury and cadmium) heavy metals, 34 species of organisms from different areas close to the Antarctic Peninsula were analysed. These included algae, filter-feeders, omnivorous invertebrates and vertebrates. Mercury was not detected, while cadmium was found in the majority of organisms analysed (detection limit was 0.05 ppm for both metals). The highest cadmium concentration was observed in the starfish Odontaster validus. Anthozoans, sipunculids and nudibranchs showed maximum levels of zinc, while the highest copper level was found in the gastropod Trophon brevispira. Mercury and cadmium levels in fishes were below the detection limit. Concentrations of essential and non-essential metals in birds were highest in liver followed by muscle and eggs. Cadmium and mercury levels in muscle of southern elephant seals were above the detection limit, whereas in Antarctic fur seals they were below it. The objective of the study was to gather baseline information for metals in Antarctic Ocean biota that may be needed to detect, measure and monitor future environmental changes.

Tissue distribution of heavy metals in small cetaceans from the Southwestern Atlantic Ocean

Abstract Tissue distribution of heavy metals (total mercury, cadmium, zinc and copper) were studied in specimens of Bottlenose Dolphin (Tursiops gephyreus), Franciscana Dolphin (Pontoporia blainvillei) and Pigmy Sperm Whale (Kogia breviceps) stranded in SW Atlantic beaches in Argentina. Heavy metal determinations were carried out by atomic absorption spectrophotometry. Liver is the most important Hg, Zn, and Cu accumulator organ in the studied specimens, while kidney is so for Cd. The importance of the trophic habits and ecological characteristics of each species related to corresponding heavy metal concentrations was emphasized, as well as the animal age vs. pollutant contents relationship. Based on these results the suitability of using these small cetaceans species as ‘heavy metals bioindicators’ in the considered environment was discussed.

Metal accumulation in tissues of sharks from the Bahía Blanca estuary, Argentina

Abstract Total mercury, cadmium, and zinc accumulation was studied in muscle and liver of three species of shark from the Bahia Blanca estuary, Argentina. The mercury concentrations were similar in both muscle (range: 0·77–2·99 μg/g) and liver (0·79–2·26 μg/g) of the analyzed species. Concentrations of cadmium and zinc were higher in liver than in muscle. The frequency distributions of metal concentrations were found to be log-normal. The metal concentrations increased proportionally to the total length of the sharks. Significant differences—attributable to location in the estuary—in metal concentrations were not found. Dietary differences among species of shark seemed to be the most important causes for differences in their metal concentrations.

Lipid metabolism of the yellow clam,Mesodesma mactroides: I. Composition of the lipids

The lipid composition of the yellow clam,Mesodesma mactroides, that lives in the northern beaches of the Buenos Aires province of Argentina was studied. The main nonpolar lipids are triglycerides and alkoxyglycerides. Phosphatidyl choline, phosphatidyl ethanolamine, and phosphatidyl serine are the main phospholipids. The predominant fatty acids are 16∶0, 16∶1ω7, 18∶0, 18∶1ω9, 20∶5ω3, and 22∶6ω3. The are mainly provided by the clams food and stored in the hepatopancreas. The content of polyunsaturated acids increases in summer together with an increase in nonpolar lipids and is correlative with an increase in phytoplankton in the sea water. Sexual maturity modifies the lipid composition of gametes.

Fate of organochlorine pesticides in soils and terrestrial biota of “Los Padres” pond watershed, Argentina

Abstract Concentrations of organochlorine pesticides (OCPs) in soils and associated biota around “Los Padres” pond watershed were determined by gas chromatography with electron capture detector (GC–ECD). Pesticides were analyzed in different horizons (upper 0–15, middle 15–30, lower 45–55 cm) of natural and horticultural soils, developed in highlands and lowlands. Physical and chemical characteristics (organic matter content, pH, moisture, texture, etc.) were determined. Higher concentrations of total OCPs were found in highlands, because of the high content of clay material and organic matter. Lindane, heptachlor, aldrin, DDT and metabolites were found in soils. Depending on physical and chemical characteristics of pesticides and soils, different behaviours were found. Lindane could leach down to lower horizons, rich in clays, while hydrophobic pesticides remain in the upper horizons, retained by organic matter. Vegetables (carrots and potatoes) accumulated lindane with important contributions of DDTs and heptachlor. OCPs were taken up, accumulated and metabolized efficiently by terrestrial invertebrates (earthworms and beetles). The results obtained testify the pollution by OCPs in “Los Padres” pond watershed.

Micronuclei induction in Rana catesbeiana tadpoles by the pyrethroid insecticide lambda-cyhalothrin

Abstract Pyrethroid lambda-cyhalothrin genotoxicity was evaluated using the micronucleus test in Rana catesbeianatadpoles.Theeffectsofconcentrationandexposuretimeonthemicronucleifrequencywerestudiedinbloodsmearsobtained from tadpoles exposed to four concentrations (0.02, 0.1, 0.2 and 0.4 µg/L) of the compound for 24, 48, 72and96hand8,15,20and30days.Asapositivecontrol,tadpoleswereexposedtocyclophosphamide(5mg/L).Themicronucleated cell frequency was expressed per 1,000 cells.R. catesbeianatadpoles exposed to increasing concentrations of lambda-cyhalothrin showed an increase in themicronuclei frequency in peripheral blood. Tadpoles exposed to cyclophosphamide (CP) also showed a significantincrease in micronucleated erythrocytes which peaked after 15 days. These results suggest that R. catesbeianatadpoles may provide a useful model for monitoring water pollution. Key words: genotoxicity, micronucleus test, lambda-cyhalothrin, tadpoles . Received: June 21, 2000; accepted: December 4, 2002.

Biochemical composition, lipid classes and fatty acids in the ovary of the shrimp Pleoticus muelleri bate

Abstract 1. 1. Seasonal changes in the biochemical composition, lipid classes and fatty acid distribution in the ovary of the shrimp P. muelleri were studied during 1984 and 1985. 2. 2. Neutral lipids were mainly composed by triaclyglycerols, free fatty acids, free and steryl sterols, partial glycerols, pigments, wax esters and hydrocarbons. 3. 3. Polar lipids included mostly phosphatidylcholine, phosphatidylethanolamine, lysoderivatives of choline and ethanolamine, sphingomyelin, pigments and unidentified glycolipids. 4. 4. Major fatty acids were 16:0, 16:1n-7, 18:1n-9, 20:5n-3 and 22:6n-3. The fatty acid composition of neutral lipids varied significantly throughout the year in contrast to that of polar lipids which remained relatively constant. 5. 5. Ovarian maturation during summer involved a simultaneous increase in ovary mass and in protein and lipid concentrations. Fully developed ovaries accumulated polar lipids and tricylglycerols. 6. 6. Palmitic acid (16:0) increased with maturation of the ovary probably as a result of de novo synthesis whereas the levels of 16:1 and 18:1 fatty acids were not significantly changed. 7. 7. After summer spawning the ovary lost large amounts of polar lipids, and in late summer the shrimp intensified feeding, as a result of which neutral lipids accumulated. The ratio of neutral lipids/polar varied from 0.5 in the summer to 2.1 in the autumn. 8. 8. The increase of the polyenoic fatty acids, 20:5n-3 in the spring (ratio 22:6 20:5 = 0.46 ) and 22:6n-3 in the autumn ( 22:6 20:5 = 1.19 ) may be caused by a change in the composition of dietary lipids.

Biosynthesis of unsaturated fatty acids in the diatomPhaeodactylum tricornutum

The biosynthesis of fatty acids in the diatomPhaeodactylum tricornutum was studied. The diatom was incubated with sodium [114C] acetate and the acids [1-14C] palmitic, [1-14C] stearic, [1-14C] linoleic and [1-14C] α-linolenic. The distribution of radioactivity in the products was determined by gas liquid radiochromatography. The diatom synthesized “de novo” not only saturated and monounsaturated fatty acids, but also linoleic, α-linolenic and other fatty acids including the highly polyunsaturated 20∶5ω3 and 22∶6ω3. When labeled acetate, stearic, α-linolenic or even linoleic acid were incubated with the diatom, the polyunsaturated C20 fatty acids synthesized belonged predominantly to the ω 3 family. The existence of Δ9, Δ6, Δ5, Δ4, ω6 and possibly ω3 desaturases inP. tricornutum is suggested.

Fatty acid metabolism in the calanoid copepodParacalanus parvus: 1. Polyunsaturated fatty acids

The metabolic fate of radioactive linoleate and α-linolenate administered to the South Atlantic copepodParacalanus parvus was studied. The wild copepod was able to incorporate the labeled acids dissolved in seawater. The radioactive linoleate was elongated to 20∶2ω6 and 22∶2ω6 and desaturated by a Δ6 desaturase to 18∶3ω6. α-Linolenate was also desaturated by a Δ6 desaturase to 18∶4ω3 and elongated to 20∶3ω3. The copepod was able to convert α-18∶3 to 20∶5ω3 and 22∶6ω3.