Effects on Ultrastructure, Composition and Specific Surface Area of the Gills of Odontesthes bonariensis Under Subchronic Glyphosate-Based Herbicide Exposure.

Gills represent one of the major sites of gas exchange of fish, consequently they are in continuous close contact with the aquatic environment and its pollutants. In the present study the effects on gills of pejerrey fish, Odontesthes bonariensis, under glyphosate-based herbicide subchronic exposure were analyzed. Adult animals were exposed to sublethal concentrations of a glyphosate-based commercial formulation (1 and 10 PMG mg L-1, PMG: glyphosate active ingredient) for 15 days, while control group was maintained in rearing water. Ultrastructural changes in gills were observed by scanning electron microscopy (SEM). The composition of the surface epithelium and specific surface area were determined by energy dispersive spectroscopy (EDS) and N2 (g) adsorption-desorption isotherms, respectively. The herbicide exposure induced severe alterations in gill ultrastructure, as shown in the SEM micrographs. Accordingly, an increase in surface area of the gills of exposed animals was determined. These results support that gills parameters of freshwater fish are sensitive morphological biomarkers for glyphosate exposure.

Pathogenic ability and saline stress tolerance of two Fusarium isolates from Odontesthes bonariensis eggs / Patogenicidad y tolerancia al estrés salino de dos aislamientos de Fusarium aislados de huevos de Odontesthes bonariensis

Background. Several fungal species represent a potential risk to embryos of Odontesthes bonariensis (Cuvier and Valenciennes, 1835), a euryhaline freshwater fish that lives in the Pampean inland waters and has potential economic relevance. Aims. To identify two fungi isolated from O. bonariensis eggs exposed to saline conditions and to characterize their pathogenicity and tolerance to sodium chloride solutions. Methods. The isolates were identified by morphological features, and a preliminar phylogenetic analysis using sequences of translation elongation factor 1-alpha (EF-1α) and calmodulin (CAM) was performed. Koch's postulates were tested to identify the causative agent of fungal infection. The influence of NaCl on the fungal growth was evaluated in in vitro assays. Results. The isolates LPSC 1001 and 1002 were identified as representatives of the genus Fusarium, and belonging to the Fusarium incarnatum-Fusarium equiseti species complex (FIESC) and the Fusarium solani species complex (FSSC), respectively. Histological observations on eggs exposed in vitro to both isolates in infectivity assays confirmed the ability of the fungal isolates to penetrate to egg's chorionic membrane, leading to the death of embryos. Increasing NaCl concentration in the culture medium reduced the growth of the isolates LPSC 1001 and 1002, being completely inhibited at 160 and 120 g/l NaCl respectively. Conclusions. The isolates LPSC 1001 (FIESC) and 1002 (FSSC) were identified as fungal pathogens to O. bonariensis eggs. The use of NaCl solutions as antifungal treatment was not effective to control the infection with these strains (AU)

Antecedentes. Diversas especies de hongos pueden representar un riesgo importante para los embriones de Odontesthes bonariensis (Cuvier & Valenciennes 1835), un pez de agua dulce eurihalino que vive en las aguas interiores pampeanas y tiene una relevancia económica potencial. Objetivos. Identificar dos especies de hongos de huevos de O. bonariensis expuestos a condiciones salinas y caracterizar su patogenicidad y tolerancia a las soluciones de cloruro de sodio. Métodos. Se identificaron los aislamientos por sus características morfológicas, y se realizó un análisis filogenético preliminar utilizando secuencias de traslación del factor 1 alfa elongación (EF- 1α) y calmodulina (CAM). Se llevaron a cabo los postulados de Koch para identificar el agente causante de la infección fúngica. La influencia de NaCl sobre el crecimiento fúngico se evaluó en ensayos in vitro. Resultados. Se identificaron los aislamientos LPSC 1001 y 1002 como representantes del género Fusarium, y pertenecientes al complejo de especies Fusarium incarnatum-Fusarium equiseti (FIESC) y al complejo de especies de Fusarium solani (FSSC), respectivamente. Las observaciones histológicas en los huevos expuestos in vitro a ambos aislamientos en los ensayos de infectividad confirmaron la capacidad de estos para penetrar en la membrana coriónica, lo que condujo a la muerte de los embriones. El aumento de la concentración de NaCl en el medio de cultivo redujo el crecimiento de los aislamientos LPSC 1001 y 1002, quedando completamente inhibidos a 160 y 120 g/l de NaCl, respectivamente. Conclusiones. Se identificaron los aislamientos LPSC 1001 (FIESC) y 1002 (FSSC) como hongos patógenos para los huevos de O. bonariensis; el uso de soluciones de NaCl como tratamiento antifúngico no resultó eficaz para el control de la infección con estas cepas (AU)

Pathogenic ability and saline stress tolerance of two Fusarium isolates from Odontesthes bonariensis eggs.

BACKGROUND: Several fungal species represent a potential risk to embryos of Odontesthes bonariensis (Cuvier and Valenciennes, 1835), a euryhaline freshwater fish that lives in the Pampean inland waters and has potential economic relevance. AIMS: To identify two fungi isolated from O. bonariensis eggs exposed to saline conditions and to characterize their pathogenicity and tolerance to sodium chloride solutions. METHODS: The isolates were identified by morphological features, and a preliminar phylogenetic analysis using sequences of translation elongation factor 1-alpha (EF-1α) and calmodulin (CAM) was performed. Koch's postulates were tested to identify the causative agent of fungal infection. The influence of NaCl on the fungal growth was evaluated in in vitro assays. RESULTS: The isolates LPSC 1001 and 1002 were identified as representatives of the genus Fusarium, and belonging to the Fusarium incarnatum-Fusarium equiseti species complex (FIESC) and the Fusarium solani species complex (FSSC), respectively. Histological observations on eggs exposed in vitro to both isolates in infectivity assays confirmed the ability of the fungal isolates to penetrate to egg's chorionic membrane, leading to the death of embryos. Increasing NaCl concentration in the culture medium reduced the growth of the isolates LPSC 1001 and 1002, being completely inhibited at 160 and 120g/l NaCl respectively. CONCLUSIONS: The isolates LPSC 1001 (FIESC) and 1002 (FSSC) were identified as fungal pathogens to O. bonariensis eggs. The use of NaCl solutions as antifungal treatment was not effective to control the infection with these strains.

Water quality of the Luján river, a lowland watercourse near the metropolitan area of Buenos Aires (Argentina).

Luján river is a lowland watercourse which runs 130 km before flowing into the Río de la Plata Estuary, and receives a mixture of domestic and industrial wastewaters originating at its margins. In order to know the physicochemical profile of its surface water, 36 physical-chemical variables were analyzed in samples collected seasonally between 2004 and 2006 at three sampling stations. The results obtained through the principal component analysis (PCA) suggest that the variations in water quality are explained by natural components (soluble salts; metals), nonpoint inputs (nutrients), and anthropogenic (organic and bacterial) and industrial (toxic heavy metals) pollutants. The cases did not fit a clear spatial or seasonal pattern when plotted against the first two PCA axes. The three water quality indices calculated gave middle scores; Sampling station 1 gave a baseline for the comparison of the river's water quality along its course while Sampling station 3 (downriver) was the most degraded. A variety of pollution pulses reach and affect the watercourse downstream. Cities' sewage discharges into the river seem to be the major polluting factor, together with natural metals and other solutes loads that are present from the headwaters. The results may be useful for the development of local and regional mitigation and remediation programs regarding toxic and eutrophying loads in the upper basin of the river.

Subcellular energy balance of Odontesthes bonariensis exposed to a glyphosate-based herbicide.

Water pollution by agrochemicals is currently one of the most critical problems for the conservation of aquatic ecosystems. Glyphosate [N-(phosphonomethyl) glycine); PMG] is the main broad-spectrum post emergence herbicide used for the control of a wide range of pests in soybean crops. Adenylate energy charge (AEC) reflects the energy balance of the cells, a measure of the energy available from the adenylate pool: adenosine triphosphate (ATP), adenosine diphosphate (ADP) and adenosine monophosphate (AMP). Background adenylates, phosphagens and the AEC index of two year old Odontesthes bonariensis were determined in some tissues by HPLC, and the impact on subcellular energy balance of sublethal glyphosate-based herbicide exposure was analyzed. The doses used were 0 (control tank), 1 or 10mg PMGL(-1), trials were carried out during 15 days. AEC values in brain, liver and muscle from control fish were 0.37 ± 0.02, 0.49 ± 0.05 and 0.56 ± 0.03, respectively (means ± SEM). While brain ATP concentrations were undetectable (hence low values of AEC), the muscle tissue showed the highest concentrations of the more energetic molecules: 0.18 µmole ATP g(-1) and 8 µmole phosphocreatine g(-1) (PCrg(-1)). In the brain, no significant changes were detected in exposed fish compared to controls. Instead, in both the liver and muscle of animals exposed to the highest concentration of the herbicide, significant changes in the AEC (reduction of 26% and 15%, p<0.05) with respect to the control group were determined. Chronic exposure (15 days) of Odontesthes bonariensis to 1 and 10mgL(-1) of formulated glyphosate did not affect brain AEC. However, the highest concentration of the herbicide produced a significant decrease in liver and muscle AEC manifesting adverse sublethal effects on the energy metabolism. These results suggest the usefulness of AEC as a biomarker of fish glyphosate exposure.

Circannual rhythms of acetylcholinesterase (AChE) activity in the freshwater fish Cnesterodon decemmaculatus.

The use of biomarkers as a tool to assess responses of organisms exposed to pollutants in toxicity bioassays, as well as in aquatic environmental risk assessment protocols, requires the understanding of the natural fluctuation of the particular biomarker. The aim of this study was to characterize the intrinsic variations of acetylcholinesterase (AChE) activity in tissues of a native freshwater teleost fish to be used as biomarker in toxicity tests, taking into account both seasonal influence and fish size. Specific AChE activity was measured by the method of Ellman et al. (1961) in homogenates of fish anterior section finding a seasonal variability. The highest activity was observed in summer, decreasing significantly below 40% in winter. The annual AChE activity cycle in the anterior section was fitted to a sinusoidal function with a period of 11.2 months. Moreover, an inverse relationship between enzymatic activity and the animal size was established. The results showed that both the fish length and seasonal variability affect AChE activity. AChE activity in fish posterior section showed a similar trend to that in the anterior section, while seasonal variations of the activity in midsection were observed but differences were not statistically significant. In addition, no relationship between AChE and total tissue protein was established in the anterior and posterior sections suggesting that the circannual rhythms observed are AChE-specific responses. Results highlight the importance of considering both the fish size and season variations to reach valid conclusions when AChE activity is employed as neurotoxicity biomarker.

Biomonitoring toxicity of natural sediments using juvenile Hyalella curvispina (Amphipoda) as test species: evaluation of early effect endpoints.

The utility of early effect endpoints as biomarkers of ecotoxicity of natural sediments in water-sediment static system was investigated. The particular goal was to evaluate the ecotoxicity of the sediment samples from La Choza stream, located in upper basin of the Reconquista river, the second most polluted river of Argentina. Native juveniles Hyalella curvispina were used as test organisms evaluating survival, growth, oxidative stress parameters (SOD; CAT, TBARS) and the electron transport system (ETS) activity as early toxic effect. This study used methodologies and techniques that allow the assessment of sediment pollution with a native species as test organism and provided data to discuss the viability of sublethal endpoints as tools for freshwater sediment assessment. In spring and in summer two ten-day series of whole-sediment assays were conducted simultaneously: (a) standard assays and (b) biomarkers assays. A control sediment was ran simultaneously in which no--effect on survival was measured. In summer there was a significant increase in length and biomass in both exposed and control groups. In spring an inhibitory effect on growth and an increase in oxidative damage with a concomitant rise in antioxidant defenses, was observed in animals exposed to La Choza sediment. ETS measurement indicated a significant depression of metabolic activity of amphipods exposed to contaminated sediments. The measured biomarkers represent the first record for juvenile H. curvispina exposed to polluted natural sediments under standardized laboratory conditions. The used bioanalytical tools demonstrated higher sensitivity and a more accurate assessment of the effects than those obtained by the standard tests of survival and growth. We propose their adoption in biomonitoring of freshwater sediment toxicity.

Effect of a reservoir in the water quality of the Reconquista River, Buenos Aires, Argentina.

The lower portion of the Reconquista River is highly polluted. However, little is known about the state of the high and middle basins. The aims of this work were to assess the water quality on the high and middle Reconquista River basins and to determinate if the presence of a reservoir in the river has a positive effect on the water quality. We conducted a seasonal study between August 2009 and November 2010 at the mouth of La Choza, Durazno, and La Horqueta streams at the Roggero reservoir--which receives the water from the former streams--at the origin of the Reconquista River and 17 km downstream from the reservoir. We measured 25 physical and chemical parameters, including six heavy metal concentrations, and performed a multivariate statistical analysis to summarize the information and allow the interpretation of the whole data set. We found that the Durazno and La Horqueta streams had better water quality than La Choza, and the presence of the reservoir contributed to the improvement of the water quality, allowing oxygenation of the water body and processing of organic matter and ammonia. The water quality of the Reconquista River at its origin is good and similar to the reservoir, but a few kilometers downstream, the water quality declines as a consequence of the presence of industries and human settlements. Therefore, the Roggero reservoir produces a significant improvement of water quality of the river, but the discharge of contaminants downstream quickly reverses this effect.

Physicochemical and ecotoxicological based assessment of bottom sediments from the Luján River basin, Buenos Aires, Argentina.

The physicochemical analysis of bottom sediments of the Lujan River was done on samples from 14 sites situated along its course and covered grain size and organic matter, total N and P, sulfides, heavy metals, organochlorine, and pyrethroid pesticides. In addition, acute 10-day whole-sediment laboratory toxicity tests were carried with each sample, using the native amphipod Hyalella curvispina as test organism. In order to correlate both types of results, data were assessed by multivariate analysis, including principal component analysis (PCA). The physicochemical profile of samples resulted similar along the river course, though several anomalous data were registered in the middle course of the river, mainly in samples taken downstream a large industrial complex; with a few exceptions in upper basin sites characterized by the dominance of agricultural activities, the pesticides concentration were consistently below the analytical detection limits. Almost 50% of the samples induced adverse effects on the amphipod when testing sublethal and lethal end points. The toxicity of the samples in terms of survival rate was extremely high in two sites, in particular in samples taken downstream the Pilar industrial complex. The integration of a selection of physicochemical and toxicological parameters of the sediments by PCA allowed discriminating areas of the river basin according the type and intensity of their particular pollution condition.

Glyphosate as an acetylcholinesterase inhibitor in Cnesterodon decemmaculatus.

The toxic effect of sublethal concentrations (1, 17.5 and 35 mg L(-1)) of pure glyphosate was evaluated on acetylcholinesterase (AChE) activity in the fish species, Cnesterodon decemmaculatus. Acute bioassays (96 h) under laboratory conditions were conducted and homogenates for each specimen corresponding to the anterior, middle and posterior body sections were performed. Fish survival was 100%, even at the highest concentration tested (35 mg L(-1)), in accordance with the low lethal toxicity reported for glyphosate. However, a significant inhibitory effect on AChE activity was recorded even for the lowest herbicide concentration tested (1 mg L(-1)), in the homogenates corresponding to the anterior body section. The inhibition ranged from 23 to 36%. The analytical determination of glyphosate in assay media by ion chromatography, was used to verify its stability. These results indicate that AChE-a neurotoxicity biomarker-in C. decemmaculatus may be affected by exposure to environmentally relevant concentrations of glyphosate.

Toxicity of waterborne Copper in premetamorphic tadpoles of Lithobates catesbeianus (Shaw, 1802).

Toxicity parameters of Copper to pre-metamorphic larvae of Lithobates catesbeianus were evaluated in laboratory conditions. The acute toxicity (as LC-50 96 h) was 3.96 mg Cu(2+) L(-1) (95% confidence interval: 3.21-4.89); the bioconcentration of the metal after 96 h exposure followed an exponential increase. The potential genotoxicity effect evaluated with Micronucleus Test showed a reduced sensitivity of the animals to the assayed concentrations of the metal, exhibiting only a modest increase in the frequency of erythrocytes micronuclei, meanwhile larvae exposed to cyclophosphamide (positive control) showed significant increases. The Condition Factor was significantly reduced while the Hepatosomatic Index remained unaltered.

Humoral immune alterations caused by lead: studies on an adult toad model

There is evidence that environmentalmetal levels affect the immune function. In the particular case of the impact of heavy metals, information available suggests that the immune system is a target for low-dose Pb exposure. Among vertebrates it was shown that amphibians are capable of forming antibodies against a variety of antigens, causing several responses such as anaphylactic response and rejectinggrafts. In this study, the production of antibodies was assessed against sheep red blood cells (SRBC) in the anuran Bufo arenarum after six weekly injections of sublethal doses of lead (50 mg.kg-1, as lead acetate). Natural antibodies (natural heteroagglutinins)were also quantified against SRBC. Both assessments were carried out employing an ELISA method developedto this end, measuring absorbance (A). For natural anti-SRBC antibodies in both control (C) and Pb treated (T) toads, there was a non significant tendency to increase the initial absorbances (C initial: 0.69+0.39 A; T initial: 0.54+0.30 A), relative to those registered at the end of the experiments (C final: 0.89+0.49 A; T final: 0.76+0.31A); the T/C ratios also did not show changes. The only significant difference was found between initial and final samples from lead-treated toads (p<0.014). The immune anti-SRBC antibody levels of toads immunized with SRBC showed a significant lower increase (p<0.05) in lead-treated animals (T final: 0.66+0.36 A), as compared to control toads (C final: 0.91+0.50 A) at the end of the experiment. It was thus concluded thatthe changes due to the assayed doses of Pb in the levels of antibodies cannot be explained on the basis of only one singleaction mechanism of the metal, but as the result of a conjunction of effects over different immunocompetent cell subpopulations. These different responses suggest that factors affecting animals exposed to a foreign stimulus are different from those influencing the response of wild animals.

Existe evidencia de que los niveles de metal ambientales afectan la función inmune. En el caso particular del impacto de metales pesados, la información disponible sugiere que el sistema inmune es un blanco para la exposición a bajas dosis de Pb. Entre los vertebrados, se ha mostrado que los anfibios son capaces de formar anticuerpos contra una variedad de antígenos, que causan diversasrespuestas, tales como respuesta anafiláctica y rechazo de injertos. En este estudio, la producción de anticuerpos fue evaluada contra eritrocitos de oveja (EO) en el anuro Bufo arenarum, luego de seis inyecciones semanales de dosis subletales de plomo (50 mg.kg-1, como acetato de Pb). Los anticuerpos naturales (heteroaglutininas naturales) fueron también cuantificados contra EO. Ambas evaluaciones fueron llevadas a cabo empleando un método de ELISA desarrollado a este fin, midiendo laabsorbancia (A). Para los anticuerpos anti-EO naturales, tanto en sapos controles (C) como en sapos tratados con Pb (T), hubo una tendencia significativa a incrementar las absorbancias iniciales (C inicial: 0,69+0,39 A; T inicial: 0,54+0,30 A); la relación T/C tampoco mostró cambios. La única diferencia significativa se encontró entre las muestras inicial y final de los sapos tratados con plomo (p<0,014). Los niveles de anticuerpos anti-EO inmune de sapos inmunizados con EO mostraron un bajo incrementosignificativo (p<0,05) en los animales tratados con plomo (T final: 0,66+0,36 A), al compararse con sapos control (C final: 0,91+0,50 A) al final del experimento. De este modo, se concluye que los cambios debidos a las dosis analizadas de Pb en los niveles de anticuerpos no pueden explicarse sólo sobre la base de un único mecanismo de acción del metal, sino como resultadode una conjunción de efectos sobre diferentes subpoblaciones de células inmunocompetentes. Estas diferentes respuestas sugieren que los factores que afectan los animales expuestos a un estimulo externo son diferentes...

Assessment of the pollution impact on biomarkers of effect of a freshwater fish.

Changes in biomarkers of fish captured from stressed environments may represent a reliable tool in revealing sublethal effects of the pollutants found in aquatic ecosystems. The response patterns of selected biochemical and morphological variables biomarkers of effect were assessed in adult females of an indigenous teleost Cnesterodon decemmaculatus, caught at a polluted site (San Francisco) of the Reconquista river (Buenos Aires, Argentina). Combined field-caging experiments with controlled laboratory exposure to clean media were performed. The biochemical parameters measured were specific activities of gill (Na+ + K+)-ATPase, liver AlaAT and AspAT, and brain AChE; LSI and CF were also calculated. The changes in gill (Na+ + K+)-ATPase and liver AlaAT activities of fish captured in the field in most cases were reversible after transfer to clean media. The results were interpreted in association with the physicochemical profile of the water samples taken simultaneously with the capture of the fish. Results suggested the suitability of the test species used as tools in environmental monitoring programs of risk assessment.

Estudios sobre los efectos etológicos del cadmio

Se estudió el efecto de soluciones de Cd2+ en concentraciones subletales sobre algunos parámetros etológicos de juveniles de un pez (carpa común, Cyprinus carpio). Se consideró el efecto del metal sobre la actividad natatoria total y las preferencias altitudinal y lateral. El metal provocó una importante depresión de la actividad natatoria total (expresada cuantitativamente mediante un Indice de actividad relativa). La preferencia altitudinal, evaluada simultáneamente, también resultó modificada, encontrándose que los peces se hallaban la mayor cantidad de tiempo en la capa superior de los acuarios. En cuanto a la preferencia lateral el resultado más importante fue la evidencia de que los peces evitaban la sección correspondiente al sitio de goteo de la solución de Cadmio, sin hallarse un patrón particular de distribución en el resto de las secciones de los acuarios. Los dos primeros parámetros fueron reversibles ya que al exponer a los peces a medios limpios (agua potable), retornaron a valores comparables con los determinados en el período Control previo a la exposición al metal

Estudios sobre los efectos etológicos del cadmio

Se estudió el efecto de soluciones de Cd2+ en concentraciones subletales sobre algunos parámetros etológicos de juveniles de un pez (carpa común, Cyprinus carpio). Se consideró el efecto del metal sobre la actividad natatoria total y las preferencias altitudinal y lateral. El metal provocó una importante depresión de la actividad natatoria total (expresada cuantitativamente mediante un Indice de actividad relativa). La preferencia altitudinal, evaluada simultáneamente, también resultó modificada, encontrándose que los peces se hallaban la mayor cantidad de tiempo en la capa superior de los acuarios. En cuanto a la preferencia lateral el resultado más importante fue la evidencia de que los peces evitaban la sección correspondiente al sitio de goteo de la solución de Cadmio, sin hallarse un patrón particular de distribución en el resto de las secciones de los acuarios. Los dos primeros parámetros fueron reversibles ya que al exponer a los peces a medios limpios (agua potable), retornaron a valores comparables con los determinados en el período Control previo a la exposición al metal

Spatial and temporal trends of physicochemical parameters in the water of the Reconquista river (Buenos Aires, Argentina).

The Reconquista river is one of the most polluted watercourses in Argentina. More than 3 million people and over 10,000 industries are settled on its basin. The available data show that pollution is mainly related to the discharge of domestic and industrial liquid wastes that are poured into the river almost untreated. At present no site of the river can be characterized as free of pollutants. Samples were taken monthly from 5 sites of the river; some 18-20 physicochemical parameters were determined in each sample. Analyses revealed significant differences in the degree of deterioration between sites. Two of them, close to the source of the river (Cascallares-S(1) and Paso del Rey-S(2)) resulted less polluted than the two points located close to the mouth of the river (San Martin-S(4) and Bancalari-S(5)). The worsening of the water quality in S(4)-S(5) was attributed to the discharges of the Moron stream, a tributary that flows into the main course of the river a complex mixture of non treated waste waters. PCA was used in the ordination of samples (sites, season and physicochemical parameters). In the PCA performed using all variables, the first principal component showed positive correlation with N-NH(4) (+), conductivity, orthophosphate, BOD(5), COD and alkalinity, and negative correlation with DO. The second principal component was positively correlated with pH, temperature and chlorophyll a and negatively with phenols and hardness. In respect to the spatial distribution, the plot of the scores for the first two components of samples taken in each sampling station showed S(1) and S(2) values displayed farthest at the left side of the X axis with high DO. In contrast, S(4) and S(5) values stayed at the right side of this axis with high N-NH(4) (+), conductivity, orthophosphate, BOD(5), COD and alkalinity; data of S(3) were "intermediate". In order to identify seasonal trends in the concentration of contaminants scores of cases labeled by season were plotted. The line drawn on the ordination plane showed that summer samples tended to converge to the upper right portion of the graph where pollution variables had more importance on the first axis, and along the second axis with high correlation with pH, temperature and chlorophyll a. Winter scores were settled in the left lower part of the plot with minor contribution of pollution parameters and more importance of DO on the first axis. Samples of autumn and spring did not fit a clear cut pattern.

Serum protein profile and blood cell counts in adult toads Bufo arenarum(Amphibia: Anura: Bufonidae): effects of sublethal lead acetate.

Lead is a multiple-source pollutant, well known for its toxicity, of great risk both for the environment and human health. The main target organs of lead are the hematopoietic, nervous, and renal systems; there are also reports in support of its impairment effects on the reproductive and immune systems. It is well known that most of the metal is accumulated in the blood cells and that many of the deleterious effects are related to its circulating concentrations. These adverse effects have been described not only in humans but also in a number of other vertebrates such as fish and birds. The purpose of the present work was to evaluate the effects of weekly administration of sublethal Pb (as acetate, 50 mg x kg(-1)) during 6 weeks on the profile of the serum proteins and blood cell counts of the adult South American toad, Bufo arenarum (Anura: Bufonidae). The electrophoretic patterns of serum proteins pointed out the presence of four fractions; the metal provoked a significant decrease in both total proteins and albumin fraction; among the globulin fractions, the G3 resulted augmented. These findings may be related to the impact of lead on the toads' hepatic cells and immune system. The number of total red blood cells (RBC) showed a tendency to decrease after the injections of the metal, whereas the number of white blood cells (WBC) increased significantly; the differential leukocyte counts showed a statistically significant increase in the absolute number and in the relative percentage of blast-like cells. The decrease in RBC was attributed to the negative impact of the metals on the hemoglobin synthesis. The increasing of the WBC counts may be interpreted as a consequence of the induction of proliferation of pluripotential hematopoietic cells.

The chemical composition of the uropygial gland secretion of rock dove Columba livia.

The uropygial gland is a holocrine secretory gland of birds. The lipid and the waxy sebum that the gland secretes is coated on the beak and transferred to the plumage in preening. The composition of the gland secretions from birds of different species has been determined, but little is known about the lipids of the secretion of the gland of the rock dove Columba livia. The amount of secretion, the total lipid content and the fatty acids composition of the secretion of C. livia captured in the nonbreeding season was reported. The mean amount of the secretion within the gland was 30 mg; the mean lipid content of the secretion was 0.385 mg/mg of secretion, which was equivalent to approximately 38% of the secretion. The weight of the secretion relative to gland weight was 32%. If we assume that the amount of the gland secretion constitutes a valid parameter to determine the degree of the gland development, our results indicate that the physiological role of the gland does not depend upon gland mass (GW); the rock dove in particular has a small gland, but its secretion represented 32% of the gland's mass. The composition of the lipids extracted from the gland secretion consisted of C14 to C20 fatty acids, most of them were unsaturated. The secretion of the gland contained approximately 59% of unsaturated fatty acids with a prevalence of oleic acid (37%) and a low content of linoleic (6%) and arachidonic acids (7%). The saturated long chain fatty acids were mainly 14:0, 16:0 and 18:0 in a percentage of approximately 34%. No sexual differences were found in any of the evaluated parameters.

Biomarkers of a native fish species (Cnesterodon decemmaculatus) application to the water toxicity assessment of a peri-urban polluted river of Argentina.

Environmental monitoring by means of biomarker parameters assessed in different species is a useful tool. It has the advantage of providing a quantitative response as well as valuable information of ecological relevance on the chronic adverse effects caused by water pollution. The aim of this study was to assess the response of biochemical and physiological parameters of Cnesterodon decemmaculatus, a native teleost, simultaneously caught in two sites of Reconquista river, a highly polluted peri-urban river. This study compared the measured parameters with that of specimens of the same species captured in an unpolluted body water, and correlated the detected changes with the physicochemical profile of the water at each site. A comparison was made of selected parameters of gill, brain and liver and of somatic indices of fish collected from polluted and reference sites. The main parameters whose changes allowed to discriminate between sampling sites were gill (Na(+),K(+))-ATPase, brain acetylcholinesterase (AChE) and liver aminotransaminases activities; tissues' protein content and liver somatic index (LSI) were also sensitive biomarkers in brain and liver, respectively. The results showed that the response of the measured biomarkers allowed for the differentiation of sampling sites according to their water quality and confirmed that Cnesterodon decemmaculatus may be a useful test organism for the biomonitoring of freshwater environments. In addition, the simultaneous measurement of the physicochemical parameters of the water samples showed a good correspondence between the biomarkers responses and the environmental chemical stress conditions.

Biosensors of inorganic lead exposure and effect in an adult amphibian.

Lead (Pb) is a ubiquitous environmental pollutant, widely distributed, representing a high toxicological and ecotoxicological risk. Several morphological, functional, and biochemical parameters have been proposed as biomarkers of effect and exposure to Pb. The information related to adverse effects of Pb is not abundant for adult amphibians. These animals are of interest, because during their development they move from aquatic to terrestrial habitats, which may be polluted by the metal since they are receptors of products generated by anthropogenic activities. Previous studies carried out on the adult South American toad Bufo arenarum (Amphibia, Anura) showed that it has a high tolerance to lead and studied the effect of sublethal doses of the metal on the erythrocyte osmotic fragility and delta-ALAD activity. It was also shown that after a single injection of Pb, a significant increase in the number of reticulocytes was produced, suggesting the suitability of those cell counts as a biomarker of exposure to the metal; its impact on the immune system of the toads was also studied. In this work we extend our early studies on the same species evaluating the chronic effect of sublethal Pb (equivalent to 5.6% of the 120-h LD-50) on free erythrocyte protoporphyrin (FEP) and blood Pb and delta-ALAD activity; blood lead was positively associated with a significant decrease in the enzyme activity and to an increase in the FEP level. Pb concentration in target organs (liver, spleen, femur, and kidney) and the total cumulated amount as well as its impact over the mass of those organs were also determined. In addition, the magnitude of the possible depuration through urine and intestine was evaluated. Our results showed that FEP, delta-ALAD, and blood Pb are reliable biosensors of chronic metal intoxication, the former being the marker with the highest sensitivity.