Alfredo Salibián

Biomarkers assessment in juvenile Cyprinus carpio exposed to waterborne cadmium

The impact of long-term exposure to waterborne cadmium (Cd) on Cyprinus carpio was evaluated through changes of selected parameters considered as biomarkers of toxicity. Fish were exposed to 1.6 mg l(-1) Cd for 14 days and then transferred to Cd-free water for 19 days. The measured parameters were gill ATPases, brain acetylcholinesterase (AchE), liver glutamate oxaloacetate (GOT) and glutamate pyruvate (GPT) transaminases, muscle water content, and protein content of liver, gills and brain. Condition factor and liver somatic index were also calculated. Branchial ATPase activities were impaired in a dissimilar way: the (Na(+),K(+))-ATPases were inhibited by approximately 30%, while the Mg(2+)-ATPase was significantly activated by 70%. Brain AchE showed no changes after Cd exposure. Both liver GOT and GPT activities were increased by the metal by 63 and 98%. Water content of the skeletal muscle showed no significant alterations. After the 19-day recovery phase, changes in the Mg(2+)-ATPase and GPT were reversed to values similar to controls, but the Cd exposure resulted in an irreversible alteration in GOT activity. Results indicate that the sublethal Cd concentrations are stressful to carp, particularly with reference to branchial enzymes which may disrupt the osmotic and ionic balance of the animals.

Freshwater pollution biomarker: response of brain acetylcholinesterase activity in two fish species ☆

The effect of prolonged exposure at two sites along the Reconquista River (Argentina), a highly polluted peri-urban water body, on brain acetylcholinesterase (AChE, EC 3.1.1.7, acetylcholine acetylhydrolase) of two teleosts was examined. Caged Cyprinus carpio and field-captured Cnesterodon decemmaculatus were used as sentinel organisms. Eserine concentration inhibiting 50% of AChE activity (IC50) and inhibition kinetic parameters were also evaluated. Interspecies IC50 differences were found to agree with observed kinetic parameters (KA, ki and kc), indicating that carps were more sensitive to eserine. Data obtained disclosed spatial differences and demonstrated the high sensitivity of AChE activity as an exposure biomarker. Marked species-related differences were detected, showing that enzyme determination of C. decemmaculatus is more effective in highly polluted sites. Considering the river water physicochemical profile, observed changes in AChE activities can be partly attributed to long-lasting raised concentrations of dissolved heavy metals.

Physiological and biochemical aspects of the avian uropygial gland.

This review discusses different aspects of the uropygial gland of birds. The gland exhibits a striking morphological diversity in size, shape and presence/absence of tufts of feathers. It was shown that acidic mucins, neutral lipids, glycolipids and phospholipids are normal components of secretion. Several morphological and physiological aspects of the gland were studied on Rock Pigeon Columba livia Gmelin, 1879. The amount of the uropygial gland secretion, its lipid content and fatty acids profile were determined. The extracted lipid mixture contained of C14 to C20 fatty acids, mostly unsaturated; the saturated fatty acids were mainly 14:0, 16:0 and 18:0. No correlation was found between the size of the gland and the aquatic/terrestrial nature of the species. Ablation of the gland did not affect survival, body weight, feeding rate and serum cholesterol, total lipids or calcium levels after 32-120 days. The possible role of the gland in the protection against lipophilic compounds was discussed. The function of the gland is still a subject of controversy. It is accepted that its secretion confers water-repellent properties on the feather coat and maintain the suppleness of the feathers. Other physiological roles of the gland secretion may be associated to pheromone production, control of plumage hygiene, thermal insulation and defence against predators. Concerning the endocrine regulation of the uropygial function, there is scarce information presenting evidence for steroid regulated mechanisms.

Enzyme activities as biomarkers of freshwater pollution : Responses of fish branchial (Na + K)-ATPase and liver transaminases

The water toxicity of the Reconquista river, an urban and industrial polluted watercourse was tested. Surface water samples from two points up and downstream of low and high pollution conditions were assayed. Continuous‐flow renewal bioassays under controlled laboratory conditions were run for 21 days. Alterations in the activity of enzymes involved in ion balance and hepatic metabolism were determined in juvenile carp Cyprinus carpio used as test species. Branchial (Na+K)‐ATPase and hepatic glutamic oxalacetate transaminase (GOT) and glutamic pyruvate transaminase activities were the selected biomarkers of toxicity. Sublethal Cd solutions were used as a reference toxic. Results showed that the activity of the enzymes were affected according to the deterioration of the river water quality. Branchial (Na+K)‐ATPase and liver GOT activity results were reliable indicators to discriminate river water samples of dissimilar pollution state. ©1999 John Wiley & Sons, Inc. Environ Toxicol 14: 313–319, 1999

Effects of zinc on the structure and growth dynamics of a natural freshwater phytoplankton assemblage reared in the laboratory.

The response of a natural phytoplankton assemblage to different concentrations of Zn(2+) was evaluated by means of a static laboratory bioassay. Aliquots of surface water, taken in autumn from a non-polluted point of the Reconquista River (Buenos Aires, Argentia), were incubated in mineral nutrient media containing 2.5, 10 or 25 mg litre(-1) of Zn(2+) (as zinc chloride). The comparative structure and dynamics of the communities were followed through periodic physico-chemical and biological analyses of samples taken during 24 days of incubation. Under the experimental conditions of the bioassays, the existence of several Zn(2+) tolerant algal species was shown: the most important of them were Chlorella vulgaris Beij. (Chlorophyceae, Chlorococcales), Nitzschia palea (Kütz.) Smith and Gomphonema parvulum (Kütz.) Kütz. (Bacillariophyceae). It was also demonstrated that the algal responses to Zn(2+) were selectively concentration dependent: at 2.5 and 10 mg litre(-1) a stimulatory effect was observed in the diatoms; at 25 mg litre(-1), diatom toxicity occurred. In contrast, Chlorophyceae growth was stimulated at the maximal Zn level. In general, the diversity, richness and equitability of the community were adversely affected by Zn in a concentration-dependent fashion.

Embryotoxicity of lead on Bufo arenarum.

Lead, one of the oldest and more widely distributed pollutants, produces serious toxicological effects. From an ecotoxicological point of view, amphibians are useful as indicators of environmental contamination because they are sensitive to a great variety of toxic agents. Considering that Bufo arenarum is one of the most widely distributed toads in South America, in the present work the authors study the LC50 and teratogenical effects of lead on Bufo arenarum embryos obtained from different couples of parents exposing them from the 2-cell stage onwards. A differential susceptibility to this heavy metal in embryos obtained from five different couples of parents is described.

Tadpoles assay: its application to a water toxicity assessment of a polluted urban river.

The acute toxicity assay with premetamorphic tadpoles of Bufo arenarum as sentinel organism was applied to evaluate the quality of two water samples taken from three sites of theReconquista River, an urban watercourse which is recipient ofboth untreated industrial effluents and domestic wastes. Theresults of the 96 hr bioassays were compared with thephysicochemical parameters determined in the samples.Mortality rates in each sample were compared using the Bonferronis test and a stepwise regression analysis of mortality andphysicochemical parameters was done. In this way, it was possible to build up consistent descriptive models which showedthat pH, Cl-, Cd2+ and Cu2+ concentrations in theriver water were significant independent variables and mightexplain, under the experimental conditions, the recordedtoxicity effects of the tested samples.Because of its simplicity, low cost and reliability it wassuggested the tadpoles bioassay be included in the set of testsused in integrated program of freshwater pollution.

Long-term in situ Toxicity Bioassays of the Reconquista River (Argentina) Water with Cyprinus carpio as Sentinel Organism

The toxicity of the Reconquista River water at Cascallares, a relatively low polluted point, was determined by means of bioassays with juvenile Cyprinus carpio as a test organism. During the summer of 1995–1996, three 30 days-long in situ caged fish tests were conducted. Changes in the activities of branchial (Na+,K+)- and Mg++-ATPases and brain AchE offish were studied. The chemical profile of the river water showed that heavymetals and phenols were the main pollutants. Gill ATPases activities were altered, while brain AchE activity resulted inhibited in one of the assays. (Na+,K+)-dependent activity was inhibited approximately 20% as compared with controls; in two assays Mg++-ATPase activity was stimulated. The condition factor of caged fish did not differ from controls.Since the protein content of gills was slightly altered, the detected changes in the enzyme activity should not be linked to alterations in the protein synthesis.

INFLUENCE OF CADMIUM ON THE RESPIRATORY FUNCTION OF THE GRASS CARP CTENOPHARYNGODON IDELLA

The effect of 96 h exposure tosublethal cadmium concentrations on oxygen consumptionrate (VO2 mg h-1) and oxygen extractionefficiency (OEE′ %) was determined in juvenile Ctenopharyngodon idella acclimated to 26, 29 and 32 °C for at least two weeks. The relationshipsamong the physiological rates (VO2 andOEE′, body weight and temperature, were fittedby second order polynomial models; the responsesurfaces generated allowed the evaluation of stressinduced by the interaction of those variables. BothVO2 and OEE′ invariably increased astemperature increased. In small animals kept in 0.5 mgCd L-1, the VO2 increase was compensated bya proportional increase in OEE′, whereas inlarger fishes (>1 g) no compensatory response wasobserved. Both small and large fishes were unable tocompensate for a higher VO2 when exposed tohigher cadmium concentration. It is concluded thatOEE′ in young fish is an early response of stressdue to sublethal cadmium exposure.

Comparative sensitivity of Scenedesmus acutus and Chlorella pyrenoidosa as sentinel organisms for aquatic ecotoxicity assessment: Studies on a highly polluted urban river

The effects of spatial and temporal differences on the water quality of the urban contaminated Reconquista River (Argentina) were evaluated by means of bioassays based on the growth of two algal populations (Chlorella pyrenoidosa and Scenedesmus acutus). The effects produced by the addition of cadmium and/or nutrient salts to the samples were also assayed. Noticeable differences in algal biomass were detected among samples from different sites, the highest values corresponding to the most polluted zones. The toxic effect of cadmium was more pronounced in S. acutus than in C. pyrenoidosa, particularly in the least polluted waters. The addition of nutrient salts to the culture medium attenuated heavy metal toxicity, mainly to C. pyrenoidosa, and also revealed nutrient limitation to algal growth in certain sites and dates. Site classifications based both on algal bioassays and on physical and chemical variables showed good agreement. ©2000 John Wiley & Sons, Inc. Environ Toxicol 15: 14–22, 2000