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.Facultad de Ciencias Naturales y Muse

Protective action of ions against cadmium toxicity to young Bufo arenarum tadpoles

Several studies have shown that a large number of amphibian species are capable of tolerating a wide range of external osmolaritles (Bentley 1971; Duellman and Trueb 1986). However, the mechanisms which respond to variations in the osmotic environment are different in larvae and adults. They are also dependent on the way that the osmotic pressure is reached, i.e., through substances which behave as ionic or no-ionic ones In solution (Ballnsky 1981). The eurihalinity of tadpoles was found in species of both Urodela and Anura. The tolerated concentration rate was wide, from distilled water to several hundreds of mOsm. In the particular case of Bufo arenarum, we have demonstrated that its young tadpoles are able to survive when immersed in distilled water, NaCI and mannitol solutions of considerably higher osmolarlties than its natural environment (Ferrari and Sallbián 1967; Ferrarl et al 1988), suggesting the existence of adaptive physiological mechanisms. We evaluated the impact of Cd(ll) on those mechanisms In the present study. Cadmium is a contaminant widely distributed in freshwater ecosystems (Ravera 1984) and known as an element that interferes in epithelial ionic permeability processes (Hayashi et al. 1977; Hillyard et al. 1979; Takada and Hayashi 1980). We hypothesized that as a consequence of those properties, Cd(II) may alter the already observed ability of Bufo arenarum tadpoles to overcome important changes in the physicochemical characteristics of their incubation media. We evaluated the effect of a sublethal concentration of this metal on the water balance of the animals immersing them in different solutions. Evidence is presented that inorganic ions have shown a protective action to the toxic effects of Cd(II).Facultad de Ciencias Naturales y Muse

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.Facultad de Ciencias Naturales y Muse

Tolerancia in vitro de Fusarium solani y Fusarium semitectum (anamorfos, Ascomycota) a la exposición a desinfectantes de superficie utilizados en acuicultura

An in vitro evaluation of the antifungal effect of acetic acid (AcH), buffered acetic acid (AcH+AcNa), potassium iodide (KI) and Iodopovidone (IP); on the growth rate (GR) of Fusarium solani (Mart.) Sacc. 1881 and Fusarium semitectum Berk. & Ravenel, 1875 was performed. Both fungal species were isolated from eggs of the Argentinian silverside Odontesthes bonariensis (Cuvier & Valenciennes, 1835). The studied substances are commonly used in fish farming as surface disinfectants. The tested concentrations of this substances exhibited antifungal activity for both strains at concentrations higher than their 96h median lethal concentrations (LC50-96h) for the treated eggs; concentrations below the (LC50-96h) exhibited little or no effect.Se evaluó in vitro el efecto del: acido acético (AcH), ácido acético tamponado (AcH+AcNa), ioduro de potasio (IK) y Iodopovidona (IP) sobre la tasa de crecimiento (TC) de Fusarium solani (Mart.) Sacc. 1881 y Fusarium semitectum Berk. & Ravenel, 1875. Ambas especies fueron aisladas de ovas de Odontesthes bonariensis (Cuvier & Valenciennes, 1835). Las sustancias estudiadas son comúnmente utilizadas en acuicultura como desinfectantes de superficie. Las concentraciones ensayadas con actividad fungicida para ambas cepas fueron mucho más elevadas que las correspondientes concentraciones letales medias a 96 horas (CL50-96h) para ovas de pejerrey. Concentraciones inferiores a la CL50 - 96h exhibieron un efecto fungistático escaso o nulo

Alteraciones inmunes humorales causadas por plomo: estudios en un modelo de sapo adulto

There is evidence that environmental metal 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 rejecting grafts. 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 developed to 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 that the changes due to the assayed doses of Pb in the levels of antibodies cannot be explained on the basis of only one single action 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 diversas respuestas, 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 la absorbancia (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&lt;0,014). Los niveles de anticuerpos anti-EO inmune de sapos inmunizados con EO mostraron un bajo incremento significativo (p&lt;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 resultado de una conjunción de efectos sobre diferentes subpoblaciones de células inmunocompetentes. Estas diferentes respuestas sugieren que los factores que afectan los animales expuestos a un estímulo externo son diferentes de aquellos que influyen la respuesta en los animales silvestres.Facultad de Ciencias ExactasComisión de Investigaciones Científicas de la provincia de Buenos Aire

Biomarcadores etológicos no invasivos de estrés ambiental: estudio comparativo en dos teleosteos de ecosistemas de la región pampeana argentina

Mediante un dispositivo de registro automático se estudió el efecto de la exposición a soluciones subletales de Cd2+ (0.3 mg. L'1) sobre algunos parámetros etológicos de juveniles de Cyprinus carpió (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. carpió 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 eífects of the exposure to sublethal Solutions of Cd2+ (0.3 mg. L2) on some ethological parameters of juvenile Cyprinus carpió (common carp) and Astyanaxfasciatus. 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 oían original device. There were determined successively the “normal” or standard levels of those parameters in control fish and those reached by the same individuáis aftertheir exposure to thereferencetoxic (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. carpió 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 individuáis of both species showed an avoidance behavior of the site of the aquaria where the Cd Solutions was dripping. This response of the animáis didn't follow a defined pattem, 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

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 ċ 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.Facultad de Ciencias Exacta

Ensayos de toxicidad de sedimentos con Hyalella pseudoazteca con cobre como tóxico de referencia

The suitability of Hyalella pseudoazteca as a test organism for sediment toxicity bioassays and the employment of the sediment from Las Flores stream as a solid control matrix were evaluated. The animals were collected from Las Flores stream and acclimated to the conditions of the laboratory. The toxicity of spiked sediments with two concentrations of Cu2+ (25 y 75 mg Cu2+/Kg dry sediment) was tested. The samples used were physicochemically analyzed and their contaminants content determined. The assay was run with five replicates on each treatment at constant temperature and photoperiod (23±1ºC; 16L/8D). The exposition time lasted ten days and for each replicate it was determined survival, biomass (dry weight) and length increase rates as end points. On the assay’s initial and final time, hardness, pH, DO, NH4 + concentration, and conductivity were measured. The statistical significance relative to control was evaluated by means of ANOVA and Tukey’s comparison test. No effect on survival was registered. There was a significant decrease of the biomass of the animals exposed to 75 mg Cu2+/Kg. The length showed a tendency to decrease in both concentrations. From the obtained results it could be concluded that Hyalella pseudoazteca is a sensitive species for the assessment of spiked sediment toxicity assays with Cu2+, being this toxic apt as reference in assays with this species. Las Flores stream’s sediment proved to be adequate as negative control sediment because of its negligible level of chemical pollution and its granulometric composition.The suitability of Hyalella pseudoazteca as a test organism for sediment toxicity bioassays and the employment of the sediment from Las Flores stream as a solid control matrix were evaluated. The animals were collected from Las Flores stream and acclimated to the conditions of the laboratory. The toxicity of spiked sediments with two concentrations of Cu2+ (25 y 75 mg Cu2+/Kg dry sediment) was tested. The samples used were physicochemically analyzed and their contaminants content determined. The assay was run with five replicates on each treatment at constant temperature and photoperiod (23±1ºC; 16L/8D). The exposition time lasted ten days and for each replicate it was determined survival, biomass (dry weight) and length increase rates as end points. On the assay’s initial and final time, hardness, pH, DO, NH4 + concentration, and conductivity were measured. The statistical significance relative to control was evaluated by means of ANOVA and Tukey’s comparison test. No effect on survival was registered. There was a significant decrease of the biomass of the animals exposed to 75 mg Cu2+/Kg. The length showed a tendency to decrease in both concentrations. From the obtained results it could be concluded that Hyalella pseudoazteca is a sensitive species for the assessment of spiked sediment toxicity assays with Cu2+, being this toxic apt as reference in assays with this species. Las Flores stream’s sediment proved to be adequate as negative control sediment because of its negligible level of chemical pollution and its granulometric composition

Effect of lead acetate on the in vitro engulfment and killing capability of toad (<i>Bufo arenarum</i>) neutrophils

Lead is an element of risk for the environment and human health and has harmful effects that may exceed those of other inorganic toxicants. The immune system is one ofthe targets of lead. Its immunomodulatory actions depend on the level of exposure, and it has been demonstrated that environmental amounts of the metal alter immune function. Very little information is available regarding the effect of the metal on different aspects of the immune system of lower vertebrates, in particular of amphibians. The aim of this study was to investigate the effect of sublethal lead (as acetate) on the function of polymorphonuclear cells of Bufo arenarum. The results revealed that phagocytic and lytic functions ofthe adherent blood cells collected from sublethal lead-injected toads and incubated with suspensions of Candida pseudotropicalis were affected negatively. The decrease of the phagocytic activity was correlated with increased blood lead levels (P-0.0001). Additional information referred to the total and differential leukocyte counts was presented; the only difference found was in the number of blast-like cells that resulted augmented in the samples of lead-injected toads. It was concluded that the evaluation ofthese parameters might be a reliable tool for the biological monitoring of the immune status of amphibians.Facultad de Ciencias ExactasComisión de Investigaciones Científicas de la provincia de Buenos Aire

Ensayos de toxicidad de sedimentos con Hyalella pseudoazteca con cobre como tóxico de referencia

The suitability of Hyalella pseudoazteca as a test organism for sediment toxicity bioassays and the employment of the sediment from Las Flores stream as a solid control matrix were evaluated. The animals were collected from Las Flores stream and acclimated to the conditions of the laboratory. The toxicity of spiked sediments with two concentrations of Cu2+ (25 y 75 mg Cu2+/Kg dry sediment) was tested. The samples used were physicochemically analyzed and their contaminants content determined. The assay was run with five replicates on each treatment at constant temperature and photoperiod (23±1ºC; 16L/8D). The exposition time lasted ten days and for each replicate it was determined survival, biomass (dry weight) and length increase rates as end points. On the assay’s initial and final time, hardness, pH, DO, NH4 + concentration, and conductivity were measured. The statistical significance relative to control was evaluated by means of ANOVA and Tukey’s comparison test. No effect on survival was registered. There was a significant decrease of the biomass of the animals exposed to 75 mg Cu2+/Kg. The length showed a tendency to decrease in both concentrations. From the obtained results it could be concluded that Hyalella pseudoazteca is a sensitive species for the assessment of spiked sediment toxicity assays with Cu2+, being this toxic apt as reference in assays with this species. Las Flores stream’s sediment proved to be adequate as negative control sediment because of its negligible level of chemical pollution and its granulometric composition.Facultad de Ciencias Naturales y Muse