Use of Lithobates catesbeianus tadpoles in a multiple biomarker approach for the assessment of water quality of the Reconquista River (Argentina).

The water quality of the Reconquista River (Argentina) water was monitored between 2009 and 2010 by means of a multiparametric approach. This periurban river is affected by agricultural, urban, and industrial discharges. Water samples were collected at a dam located in the headwaters and at 18 km downstream (M). Physicochemical profile and two water-quality indices (WQIs) were determined. Laboratory bioassays were performed by exposing Lithobates catesbeianus tadpoles to environmental samples for 96 h and determining the following parameters: (1) brain: acetylcholinesterase (AChE) activity; (2) gill: catalase and glutathione-S-transferase (GST) activities and glutathione (GSH) content; (3) liver: CAT and GST activities, superoxide dismutase, lipid peroxidation, and GSH content; (4) condition factor and hepatosomatic index; and (5) genotoxicity [micronucleus (MN) test in erythrocytes]. Physicochemical profile and WQIs corresponded with extensive pollution in M. Important temporal and spatial variability in biomarkers of tadpoles exposed to samples was found. Multivariate analyses showed that AChE in brain, MN frequency, liver and gill GST activities, and GSH content were key biomarkers.

Energy balance of juvenile Cyprinus carpio after a short-term exposure to sublethal water-borne cadmium.

Stress in fish can be assessed by means of a bioenergetic approach, based on the evaluation of changes in their physiological parameters. The objective of this study was to determine the impact of sublethal water-borne cadmium (Cd) on the energetic balance of juvenile Cyprinus carpio under laboratory conditions after a short-term exposure. Fish were exposed to a concentration of Cd (0.15 mg Cd l(-1)) for 2 weeks. This concentration is environmentally realistic since it is usually found, even at higher values, in heavily polluted periurban water bodies of Argentina. No mortality was recorded among the animals used in the experiments. Food intake, food assimilation and assimilation efficiency, fecal production, liver glycogen content, oxygen consumption, oxygen extraction efficiency, specific metabolic rate, ammonia excretion and ammonia quotient (AQ), condition factor, and liver somatic index were determined. The overall balance was expressed as the scope for growth (SFG). The morphological indices and the liver glycogen content of Cd-exposed fish showed no significant differences when compared to those of controls. There was a significant decrease in the food intake, fecal production, and food assimilation rates as well as in AQ; the SFG exhibited a highly significant decrease. The remaining parameters (assimilation efficiency, oxygen consumption, oxygen extraction efficiency, specific metabolic rate, and ammonia excretion) increased after the exposure to Cd. We concluded that the sub-chronic exposure of Cyprinus carpio to a sublethal concentration of Cd causes important alterations in the energy-related homeostasis of fish. Most of the responses are indicative of physiological adaptations to compensate an increased energy requirement due to the impairments caused by the metal.

Water-balance response of Rhinella arenarum (Hensel, 1867) tadpoles to graduated increase in environmental osmolarity.

The water balance and the upper limit of osmotic tolerance of premetamorphic Rhinella arenarum larvae (Gosner's stage 26) was evaluated after semistatic incubation in electrolyte (NaCl) and non-electrolyte (mannitol) media following a protocol of progressively increased osmotic pressure. Wet and dry weights were measured to calculate the water content as a derived variable indicative of the hydric balance. Statistical analysis was performed using univariate and integrated multivariate analysis. Tadpoles survived in electrolyte and non-electrolyte solutions up to 200 mOsm. The discriminant function was the best tool to describe the responses of the animals to external environmental stress under experimental conditions. The results were compared with those obtained in previous studies using a protocol of acute exposure to the same media used in this study. It was concluded that a) multivariate analysis is an appropriate approach to describe the responses of tadpoles to changes in the environmental physicochemical parameters, and b) progressive and acute acclimation to the experimental solutions induced similar responses.

Water-balance response of Rhinella arenarum (Hensel, 1867) tadpoles to graduated increase in environmental osmolarity / Resposta de Rhinella arenarum larvae a meio electrolítico e não electrolítico com aumento escalonado da osmolaridade

The water balance and the upper limit of osmotic tolerance of premetamorphic Rhinella arenarum larvae (Gosner's stage 26) was evaluated after semistatic incubation in electrolyte (NaCl) and non-electrolyte (mannitol) media following a protocol of progressively increased osmotic pressure. Wet and dry weights were measured to calculate the water content as a derived variable indicative of the hydric balance. Statistical analysis was performed using univariate and integrated multivariate analysis. Tadpoles survived in electrolyte and non-electrolyte solutions up to 200 mOsm. The discriminant function was the best tool to describe the responses of the animals to external environmental stress under experimental conditions. The results were compared with those obtained in previous studies using a protocol of acute exposure to the same media used in this study. It was concluded that a) multivariate analysis is an appropriate approach to describe the responses of tadpoles to changes in the environmental physicochemical parameters, and b) progressive and acute acclimation to the experimental solutions induced similar responses.

Avaliou-se o balanço hídrico e o limite superior de tolerância osmótica em larvas pré-metamórficas do Rhinella arenarum (etapa 26 de Gosner) sob condições de incubação semiestáticas, num meio eletrolítico (NaCl) e não eletrolítico (manitol), seguindo um protocolo de aumento progressivo da pressão osmótica do meio. A quantificação das respostas se efetuou por meio da medição dos valores de peso úmido e seco e do cálculo, a partir destes, do conteúdo de água, como variável derivada indicativa do equilíbrio hídrico. A análise estatística foi realizada usando análise univariada e multivariada. As larvas conseguiram sobreviver em soluções eletrolíticas e não eletrolíticas até 200 mOsm. A função discriminante foi a melhor ferramenta para descrever as respostas dos animais ao estresse osmótico ambiental. Os resultados foram comparados com os obtidos em estudos anteriores, usando um protocolo de exposição aguda aos mesmos meios de incubação usados neste estudo. Concluiu-se: a) a análise multivariada é a aproximação adequada para descrever as respostas das larvas às mudanças nos parâmetros físico-químicos do seu meio; e b) tanto a aclimatação progressiva, como as exposições agudas às soluções experimentais induziram as respostas semelhantes.

Quantitative behavioral parameters as toxicity biomarkers: fish responses to waterborne cadmium.

The disruptive sublethal effects of heavy metals on behavioral parameters of fish as biomarkers of aquatic toxicity have been scarcely studied. We investigated the impact of exposure to sublethal waterborne cadmium on locomotory parameters of three freshwater teleosts: Cyprinus carpio as reference species, and Australoheros facetum (sin. Cichlasoma facetum) and Astyanax fasciatus, native to Pampean ecosystems in Argentina, using a noninvasive bioassay under laboratory conditions. Fish were successively transferred to media containing freshwater (control period), Cd(2+) solutions (exposure period), and freshwater (recovery period). The behavioral biomarkers evaluated were swimming activity and swimming speed of fish. The metal provoked different responses of both parameters after 4-7 days of exposure; the reversibility of changes was also assessed. It was concluded that: (a) locomotion parameters are sensitive endpoints and useful biomarkers in behavioral studies of freshwater toxicity, (b) the applied bioassay could be a valuable tool in water quality monitoring, and (c) the studied species differed in their susceptibility to the toxicant as well as in their capacity to return to basal values.

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.

Physiological and biochemical aspects of the avian uropygial gland / Aspectos fisiológicos e bioquímicos da glândula uropigial das aves

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.

Esta revisão discute diferentes aspectos da glândula uropigial das aves. A glândula exibe uma chamativa diversidade morfológica de tamanho, forma e presença/ausência de um tufo de penas. A glândula mostrou mucinas ácidas, lipídios neutros, glicolipídios e fosfolipídios como componentes normais de sua secreção. Diversos aspectos morfológicos e fisiológicos da glândula foram estudados na pomba doméstica Columba livia. Foi determinada a quantidade de secreção da glândula uropigial, seu conteúdo lipídico e o perfil de ácidos sebosos. A mistura lipídica extraída contém ácidos graxos C14 a C20, principalmente não saturados; os ácidos graxos saturados foram principalmente 14:0, 16:0 e 18:0. Não se encontrou correlação entre o tamanho da glândula e a natureza aquática/terrestre das espécies. A ablação da glândula não afetou a sobrevivência, peso corporal, alimentação e os níveis séricos de colesterol, lipídios totais ou cálcio depois de 32-120 dias. Discute-se o possível papel da glândula na proteção contra compostos lipofílicos. A função da glândula é ainda tema de controvérsia. Aceita-se que sua secreção confere às penas propriedades repelentes à água e as mantém flexíveis. Outras funções fisiológicas da secreção glandular podem estar associadas com a produção de feromonas, controle da higiene da plumagem, isolamento térmico e defesa contra predadores. Com relação à regulação endócrina da glândula, tem-se escassa informação, apresentando evidência de mecanismos de regulação de esteróides.

Removal of the uropygial gland does not affect serum lipids, cholesterol and calcium levels in the rock pigeon Columba livia.

The uropygial gland is an organ typical of birds, over which no agreement regarding its function has been attained yet. Authors attribute to the gland an hydrophobic action. The function of the gland is herein explored in rock pigeon, Columba livia, was used as experimental model for trials. The study was focused on the physiological role of the gland in relation to biochemical parameters. Pigeons were separated in groups of six birds each: a) intact control, b) surgical control, c) ablationed. Comparing control specimens with gland-removed specimens, recorded serum levels after 32 days were the following (mean+/-SD): cholesterol (g/l), 3.7+/-0.6 vs. 4.1+/-0.6; total lipids (g/l), 15.7+/-2.0 vs. 13.7+/-2.7; calcium (mg/l), 100.5 +/- 24.3 vs. 99.1 +/- 9.2. None of the differences were statistically significant. Thus, no alterations of basic biochemical parameters associated with metabolism of lipids were registered. In one group of birds the calcium and cholesterol levels were determined 122 days after surgery; in this case values remained unchanged related to the beginning of the trials. Results suggest that the uropygial gland is not physiologically related to either the homeostasis of total lipids, cholesterol or the regulation of calcium metabolism.

Biomarcadores etológicos no invasivos de estrés ambiental: estudio comparativo en dos teleosteos de ecosistemas de la región pampeana argentina / Non invasive behavioural biomarkers of environmental stress: comparative study on two teleosts from ecosystems of the pampean region of Argentine

Mediante un dispositivo de registro automático se estudió el efecto de la exposición a soluciones subletales de Cd2+ (0.3 mg. L ) sobre algunos parámetros etológicos de juveniles de Cyprinus carpio (carpa común) y de Astyanax fasciatus (“mojarra”). Se evaluó el efecto del metal sobre la actividad natatoria total y las preferencias altitudinales y laterales de los peces. Los tres parámetros se registraron simultáneamente mediante un dispositivo original. Se evaluaron los niveles “normales” o estándar de dichos parámetros (los peces en agua potable, control) y los alcanzados por los mismos individuos tras su exposición al tóxico de referencia (Cd). El metal provocó una depresión de la actividad natatoria total alcanzando una magnitud comparable en ambas especies. La preferencia altitudinal, también resultó modificada: C. carpio se halló con mayor frecuencia en la capa superior de los acuarios mientras que A. fasciatus se ubicó en las inferiores. En cuanto a la preferencia lateral, los individuos de ambas especies evitaron la franja vertical donde se producía el goteo de la solución de Cd; si bien esta respuesta espacial de los animales no siguió un patrón definido fue más marcada en las carpas. Todas las respuestas se pusieron de manifiesto inmediatamente después de haberse iniciado la exposición al Cd. El método resultó sensible y apto para el seguimiento de los parámetros etológicos seleccionados. Se concluye que la actividad natatoria y la ubicación espacial de las especies estudiadas, entre otros indicadores, pueden ser considerados como biomarcadores de toxicidad acuática

By means of an automatic recording device, the effects of the exposure to sublethal solutions of Cd2+ (0.3 mg. L ) on some ethological parameters of juvenile Cyprinus carpio (common carp) and Astyanax fasciatus. The effect of the metal was evaluated through three parameters: the total swimming activity and the spatial (lateral and altitudinal) preferences, relative to controls (fish kept in tap water); they were registered simultaneously by means of an original device. There were determined successively the “normal” or standard levels of those parameters in control fish and those reached by the same individuals after their exposure to the reference toxic (Cd). In both species the metal caused a depression of the total swimming activity in a comparable magnitude. The altitudinal preference was also modified: C. carpio was found more frequently in the superior layer of the aquaria while A. fasciatus was found in the inferior ones. For the lateral preference, the individuals of both species showed an avoidance behavior of the site of the aquaria where the Cd solutions was dripping. This response of the animals didn t follow a defined pattern, but was more marked in the carps. All the evaluated responses to the toxic were detected immediately after the beginning of the exposure to Cd. The method proved to be sensitive and apt for the monitoring of the measured behavioural parameters which makes it a promising tool for biomonitoring purposes. We concluded that the swimming activity and the spatial location preferences of the studied species, among other, may be considered as biomarkers of aquatic toxicity

Ecotoxicological assessment for receiving waters with the premetamorphic tadpoles acute assay.

The toxicity of receiving waters was evaluated by means of the young tadpoles assays. The sentinel organism was Bufo arenarum, an indigenous anuran species. The assayed water samples were taken from a highly polluted urban watercourse (Reconquista River, Buenos Aires, Argentina), characterized by high concentration of nitrites, phosphates and heavy metals. The toxicity of water samples was assessed performing the pass-fail test and by means of the NOEC and LC(50); TUs (toxic units) were also calculated. The effect of the addition of a positive control (Cd) on the toxicity of the river water samples was also examined. Water samples of three sites, characterised by their different degree of pollution, were assayed. The lethal response had a clear cut correspondence with the water quality of the sample evaluated by means of physicochemical parameters. In most cases, the dilution of the samples resulted in a significant reduction of their toxicity to TU values compatible to those stated by the USEPA for industrial effluents. It was concluded that (a) the used Bufo arenarum bioassay was an adequate method for assessing the toxicity of natural polluted water samples and (b) the three considered endpoints showed no important differences after 48 or 96 h of exposure, therefore we concluded that it may not be necessary to extend the assay for a longer period than 48 h.

Oromandibular reconstruction with vascularized free flaps: a review of 50 cases.

Fifty cases of oromandibular reconstruction using vascularized free flaps to evaluate functional parameters of results were evaluated. There were 23 iliac crest flaps, 17 fibula flaps, 30 ulnar forearm flaps, and 3 radial forearm flaps with bone. Thirteen female and 37 male patients comprised the study, with a mean age of 57.66 years. Squamous-cell carcinoma (SCC) constituted 86% of cases, of which 60% were T4 lesions and 13.9% were recurrent. Anterolateral mandibular defects constituted 48.7%, and the mean bone gap was 8.13 cm. Functional evaluation was based on the University of Washington Questionnaire (UWQ) through phone calls and personal communication. The mean hospital stay was 12.42 days. The external carotid (75%) and facial (18.3%) were the main recipient arteries. The internal jugular (47.05%) was the main recipient vein. Overall flap survival was 95.9%. Three flaps were lost due to unsalvageable venous thrombosis. Major local complications such as partial flap loss, hematoma, and orocervical fistula constituted 10% of cases. Speech was classified as "excellent" and "good" in 43.3% of cases. Swallowing was identified as "excellent" and "good" in 53.3% of cases. Cosmetic acceptance was rated "good" in 63.3% of cases. Vascularized free flap reconstruction of oromandibular defects provides excellent functional and aesthetic results. The majority of patients are able to tolerate a regular diet. Intelligible speech and acceptable appearance are restored, providing patient satisfaction.

Role of ulnar forearm free flap in oromandibular reconstruction.

The ulnar forearm flap is not frequently utilized for oromandibular reconstruction. This study evaluated the usefulness of the ulnar free flap for reconstruction. A retrospective study of 32 patients was conducted. The ulnar forearm flap was combined with an osseous flap in 24 patients. Nine females and 23 males with a mean age of 58.15 years comprised our study population. Squamous-cell carcinoma was the diagnosis in 93.75% of cases (56.25% T4), of which 20% were recurrent. Functional evaluation of swallowing was based on the University of Washington Questionnaire (UWQ). The mean hospital stay was 9.8 days. The external carotid (100%) was the recipient artery, and the internal jugular (74.07%) was the main recipient vein. Overall flap survival was 96.8%. One flap was lost due to unsalvageable venous thrombosis. Major local complications were seen in 9.4% of cases and included partial flap loss, hematoma, and an orocutaneous fistula. At the time of this study, 21 patients were available for functional evaluation. Speech was rated excellent and good in 33.3% of patients. Swallowing was found good in 28.6% of patients. Chewing was rated excellent and good in 47.6% of patients. Cosmetic acceptance was rated good in 71.4% of cases. The ulnar forearm is a useful free flap in oromandibular reconstruction. It is available when the radial artery is the dominant artery of the hand. Being more hidden, it may be more cosmetically accepted. It affords pliable soft tissue for lining and/or covering of oromandibular defects, and can be used as a second choice after other free-flap failures.

Influencia de la especiación de los metales pesados en medio acuático como determinante de su toxicidad / Influence of the heavy metals speciation in the aquatic environment as determinant of their toxicity

La captación y toxicidad de los metales pesados para los organismos acuáticos están influidos no sólo por su concentración; también son relevantes el tiempo de exposición y los factores bióticos y abióticos del ambiente. Para considerar las relaciones de los metales con la biota acuática se deben tener en cuenta tres niveles de interés: a) la especiación en el ambiente, b) las interacciones con la membrana plasmática en la interfase organismo-ambiente, así como otros factores secundarios que pueden afectar los mecanismos funcionales básicos del individuo y c) la partición del elemento en los compartimentos del organismo y los efectos biológicos resultantes de su interacción con los receptores en los sitios de acción. En esta revisión se presentan ejemplos que ilustran la necesidad de determinar no sólo la concentración total de un metal en solución acuosa sino también el perfil de su entorno fisicoquímico y su biodisponibilidad; esta última puede ser correlacionada directamente con la especiación química a través del modelo de actividad del ion libre (en inglés, FIAM, free ion activity model). Se discute además la posibilidad de usar organismos como sensores de la biodisponibilidad de los metales en relación con su especiación química. Dentro de ellos, las algas representan un grupo muy importante ya que muestran una sensibilidad a los contaminantes mucho mayor que otros organismos acuáticos. Se presentan resultados propios obtenidos mediante bioensayos de laboratorio, usando cultivos algales monoespecíficos de Selenastrum capricornutum Printz (= Raphidocelis subcapitata); se ha estudiado el efecto del Cd sobre la inhibición de la fotosíntesis en presencia del quelante EDTA-Na2. Los resultados muestran que la concentración total del Cd no es un buen predictor de su toxicidad para las algas y que su especiación puede afectar la disponibilidad del mismo para los organismos en medio acuático y, consecuentemente, determinar la magnitud de su toxicidad (AU)

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.

Monitoring of organochlorine and organophosphorus pesticides in the water of the Reconquista River (Buenos Aires, Argentina).

The Reconquista river is a typical example of the adverse impact of human activity on a watercourse. Approximately 10% of the population of the country is settled on its basin and it receives wastewater discharges from residences and industries. This paper describes the results of the first systematic data for measurement of pesticides in surface water of the river, based on a monthly monitoring program over two-year span. The analyses were performed, in three sampling stations (S1, S2 and S3), along 46 km of its course, following the AOAC methods. Screening included the following pesticides: (a) Organochlorines: alpha, beta and gamma HCH; heptachlor, heptachlor epoxide; aldrin; endrin; dieldrin; op' and pp' DDT; op' and pp' DDE; alpha and gamma chlordane and endosulphan II; (b) Organophosphates: ethyl and methyl parathion; chlorpyrifos and fenitrothion. From the 60 samples analyzed, 35% contained organochlorine pesticides in a concentration higher than the detection limit. Organophosphates were found in no case. Throughout the studied period, DDT and its metabolite DDE were only found in S1 and gamma chlordane in S3; heptachlor was present in 50% of the samples of S2 and in 35% of S3, while HCH isomers were detected in 38% of S2 and 45% of S3 samples. Neither temporal nor spatial trends were found. There was not a relationship between the time of samplings and the fumigation season for farming purposes. At all locations, pesticides levels were found to be between 40 and 400 times higher than the legal limits established for protection of aquatic life.

Blood lead content in a peri-urban population of the South American toad Bufo arenarum.

Blood Pb concentration in a South American toad Bufo arenarum population (n = 152) was determined over 10 samplings carried out between December 1996 and November 1999. The studied population lived in the surroundings of the La Plata City, the largest industrial-urban setting of the Buenos Aires Province, Argentina. The presence of the metal was detected in all the samples tested, the mean concentration range being 1.99-4.66 mg dl(-1). Some preliminary environmental data on soil content of Pb in the sampling area suggest the anthropogenic origin of the metal possibly due to high rate of Pb-containing gasoline utilisation until recently. The reported results may reflect a sequel of a sustained local air-soil-water pollution process.

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 the Reconquista River, an urban watercourse which is recipient of both untreated industrial effluents and domestic wastes. The results of the 96 hr bioassays were compared with the physicochemical parameters determined in the samples. Mortality rates in each sample were compared using the Bonferroni's test and a stepwise regression analysis of mortality and physicochemical parameters was done. In this way, it was possible to build up consistent descriptive models which showed that pH, Cl- Cd2+ and Cu2+ concentrations in the river water were significant independent variables and might explain, under the experimental conditions, the recorded toxicity effects of the tested samples. Because of its simplicity, low cost and reliability it was suggested the tadpoles bioassay be included in the set of tests used in integrated program of freshwater pollution.

Blood lead concentration and delta-aminolevulinic acid dehydratase activity in adult Bufo arenarum.

The effects of sublethal doses of lead (as acetate) on blood parameters of adult male Bufo arenarum were studied. Toads received one single injection with 10, 25, 50 or 100 mg/kg of body weight, equivalent to approximately 1/90-1/10 of the 120 h-LD50; seven days after the injections, the hematocrit and the blood delta-aminolevulinic acid dehydratase (ALAD) activity were measured. Hematocrit of lead-injected animals did not exhibit significant changes respective to controls that received sodium acetate (range 29.8-38.8%). Blood lead concentrations were positively and significantly correlated with the injected metal doses. Blood ALAD activity declined proportionately to the doses of the metal as well as to its whole blood concentration. Because of its sensitivity and specificity, it was concluded that the activity of delta-ALAD may be adopted as a reliable biomarker of Bufo arenarum experimental lead intoxication.

A useful model to study the effect of high sugar concentrations upon growth and enzymic activities of toad embryos and larvae.

The aim of this study was to develop an oviparous model suitable for studying the differential effects and mechanisms by which a high concentration of extracellular glucose and other sugars produce diabetes complications, particularly body growth retardation during development. Hence, we studied the experimental conditions necessary to obtain measurable effects of high sugar concentrations (5-mM glucose, mannitol, fructose and galactose) upon body growth and development of Bufo arenarum embryos and larvae, and upon the activity of aspartate aminotransferase (AST), gamma-glutamyltransferase (GGT), and alkaline phosphatase (APP). Unfed animals kept in glucose showed lower body weight than controls at all stages, a condition only observed at stage 26 for animals kept in galactose and fructose. All animals reached the same stage of development regardless of the solution in which they were kept. Glucose and fructose significantly decreased the activity of all enzymes tested, while galactose only affected GGT activity. The model provides the first experimental evidence for the deleterious effect exerted in vivo by different sugars upon developing embryos and larvaes of Bufo arenarum. The results prove that this model might help to elucidate the effects and the pathogenic mechanisms of hyperglycemia upon growth and development of embryos exposed to environments with high sugar concentrations. It might also become a useful tool for testing the effectiveness of drugs designed to prevent the deleterious effect of such exposure.