Effects of the organophosphorus pesticide Folisuper 600 (methyl parathion) on the heart function of bullfrog tadpoles, Lithobates catesbeianus (Shaw, 1802) / Efeitos do pesticida organofosforado Folisuper 600 (metil paration) sobre a função cardíaca de girinos de rã-touro, Lithobates catesbeianus (Shaw, 1802)

Abstract The aim of this work was to evaluate whether the heart function of bullfrog tadpoles (25 Gosner stage) is affected by their acute exposure (48 h) to a sub-lethal concentration (10 µg.L–1) of the active principle of the organophosphorus pesticide Folisuper 600R (methyl parathion - MP). Our results demonstrated that MP causes not only a reduction in tadpoles’ cardiac ventricular mass, resulting in a marked reduction in their cardiac twitch force, but also impairs their swimming performance, irrespective of increasing their heart rate. Together, these findings indicate that low and realistic concentration of MP have a negative impact on tadpoles’ performance, jeopardizing their survival.

Resumo O objetivo do presente estudo foi avaliar se a função cardíaca de girinos de rãs-touro (estágio 25 de Gosner) é afetada pela exposição aguda (48h) a uma concentração sub-letal (10 µg.L–1) do princípio ativo do pesticida organofosforado Folisuper 600R (metil paration – MP). Nossos resultados demonstraram que o MP ocasionou não apenas uma redução na massa ventricular cardíaca dos girinos, como também provocou uma redução na sua força de contração cardíaca e de seu desempenho natatório, a despeito de ter sido observado um aumento de sua freqüência cardíaca. Conjuntamente, os achados aqui obtidos indicam que uma baixa e realística concentração de MP exerce um impacto negativo sobre o desempenho dos girinos, ameaçando sua sobrevivência.

Is hypoxia a stressor to American bullfrog tadpoles? / A hipóxia é um estressor para girinos de rã-touro?

The aim of this study was to evaluate alterations to the physiological profile of cortisol in pro-metamorphose phase tadpoles of Lithobates catesbeianus exposed to hypoxia stressor in a capture experiment and in a crowding experiment. The capture study was performed by the treatments: stress due to individual capture with a hand net, stress due to batch capture with a hand net and stress due to capture by emptying. Three simultaneous replicates was done witch 12 animals were sampled (6 normoxia - immediately blood collection) and 6 hypoxia - blood collection after 15 min of air exposition) in two collection times with 5 days by intervals. The crowding study was performed by the treatments 1 tadpole L-1, 5 tadpoles L-1 and 10 tadpoles L-1. Three simultaneous replicates was done witch 8 animals (4 normoxia and 4 hypoxia) were sampled in the zero moment (ZM) - blood collection before the experiment, 6 animals/treatment (3 normoxia and 3 hypoxia) to 4 and 8 days and 18 animals/treatment (9 normoxia and 9 hypoxia) to 12 days. The average values to plasmatic cortisol varying from 1.7 to 5.1ng mL-1 (capture study) and 1.0 to 4.2ng mL-1 (crowding study). It concludes that the biomarker tested (cortisol) showed no alterations front of the stressor used. Alternatively, a larger response pattern to these stimuli may have been expressed in another level of an unmeasured hormone (corticosterone). And the bullfrog has great ability to adapt to different management compared to other aquatic organisms, which demonstrates the plasticity of these animals.

Avaliou-se o cortisol em girinos de rã-touro (Lithobates catesbeianus), no estágio de pró-metamorfose ao mecanismo estressor de hipóxia juntamente com captura (1º experimento) e adensamento (2º experimento). O experimento de captura foi composto pelos tratamentos: Captura individual com puçá, Captura em massa com puçá e Captura por escoamento, com 3 réplicas simultâneas onde 12 organismos foram amostrados (6 normoxia - coleta imediata de sangue e 6 hipoxia - coleta de sangue após 15 min de exposição ao ar) em 2 tempos de coleta com intervalo de 5 dias. O experimento de densidade foi composto pelos tratamentos: 1 girino L-1, 5 girinos L-1 e 10 girinos L-1, com 3 réplicas simultâneas onde 8 animais (4 normoxia e 4 hipoxia) foram amostrados no momento zero (MZ) - coleta de sangue anterior ao experimento, 6 animais/tratamento (3 normoxia e 3 hipoxia) para 4 e 8 dias e 18 animais/tratamento (9 normoxia e 9 hipoxia) para 12 dias. Os valores médios para o cortisol plasmático foram de 1,7 a 5,1ng mL-1 (Experimento de Captura); e 1,0 a 4,2ng mL-1 (Experimento de Densidade). Conclui-se que o marcador biologico de estresse utilizado (cortisol) não foi alterado pelo agente extressor. Alternativamente a resposta a este estímulo pode ser expressa em outro nível hormonal (corticosterona). E a rã-touro apresenta ótima capacidade de se adaptar aos diferentes manejos se comparados a outros organismos aquáticos, o que demonstra a plasticidade destes animais.

Profile of cortisol, glycaemia, and blood parameters of American Bullfrog tadpoles Lithobates catesbeianus exposed to density and hypoxia stressors / Perfil de cortisol, glicemia, e parâmetros sanguineos de girinos de rã-touro Lithobates catesbeianus expostos a diferentes densidades e hipóxia

The aim of this study was to evaluate alterations to the physiological profile (cortisol, glycaemia, and blood parameters) of Lithobates catesbeianus caused by the stressors density and hypoxia. The organisms were in the prometamorphosis stage and exposed to different tadpole densities: 1 tadpole/L (T1), 5 tadpoles/L (T2), and 10 tadpoles/L (T3) for 12 days. The blood was collected through the rupture of the caudal blood vessel and collected under normoxia (immediate collection) and hypoxia (after 15 minutes of air exposure) conditions. Cortisol levels rose on the fourth and eighth days of treatment and returned to basal levels by the end of the experiment. The stressor mechanisms tested did not affect glycaemia. White blood cells (total number of lymphocytes, neutrophils, and eosinophils) showed a significant difference at the twelfth day of the experiment when compared with the start of the experiment. We concluded that, under controlled conditions, a density of up to 10 tadpoles/L and air exposure for 15 minutes did not cause harmful physiological alterations during the experimental period. The answer to these stressors maybe was in another hormonal level (corticosterone).(AU)

O objetivo deste estudo foi avaliar a resposta fisiológica (cortisol, glicemia e parâmetros sanguineos) de girinos de rã-touro (Lithobates catesbeianus) em diferentes densidades e após exposição aérea. Os animais utilizados no experimento estavam entre os estágios 31 a 39, na fase de pró-metamorfose sendo testados 1 girino/L (Tratamento 1), 5 girinos/L (Tratamento 2) e 10 girinos/L (Tratamento 3), conduzidos em 3 réplicas simultâneas durante 12 dias. O sangue foi retirado por rompimento do vaso caudal na condição de Normóxia - N (tempo zero) e Hipóxia - H (tempo de 15 minutos de exposição ao ar). Foi observado um aumento nos valores de cortisol, aos 4 e 8 dias de exposição aérea retornando aos valores basais ao final do experimento, apesar de não haver diferenças significativas. A glicemia não apresentou diferenças significativas quanto aos estressores aplicados. Os parâmetros hematológicos da série branca, principalmente, o número de linfócitos, neutrófilos e eosinófilos mostraram diferença significativa aos 12 dias de experimentação quando comparados com o momento zero; concluindo-se que, em condições controladas, o adensamento de até 10 girinos/litro e a exposição aérea por 15 minutos não apresentou danos aos girinos de rã-touro durante o período experimental. O padrão de resposta a estes estímulos talvez seja expresso em outro nível hormonal (corticosterona).(AU)

Estudio morfológico, morfométrico e histoquímico de los epitelios de revestimiento y glandular de la lengua de la rana toro, rana catesbeiana / Morphological, morphometrical and histochemical study of the lining and glandular epithelia of the tongue of the tullfrog rana catesbeiana

La superficie dorsal de la lengua de la rana toro, Rana catesbeiana, presenta un epitelio simple cilíndrico, constituido por células caliciformes y raras células ciliadas. El dorso de la lengua posee numerosas papilas filiformes y algunas fungiformes. Las primeras poseen un epitelio simple cilíndrico, con células secretoras, mientras que las segundas poseen en la región apical, un disco sensorial con epitelio estratificado cilíndrico, con células basales, periféricas, glandulares y receptoras. A lo largo del dorso de la lengua existen numerosas glándulas tubulares, que penetran en profundidad, entremezclándose con las fibras musculares. El epitelio glandular es simple cilíndrico, con células secretoras y de sostén. Las primeras son las únicas en la base de la glándula y las segundas solo se encuentran en número escaso en el tercio superior. La superficie ventral de la lengua posee un epitelio estratificado, con células caliciformes y, entre éstas, células ciliadas. La morfometría de las glándulas mostró que son más cortas en la región anterior de la lengua (330 um) que en la región posterior (450 um). Las células secretoras de las glándulas linguales anteriores son menores (1457,7 um3) que en las posteriores (2645,9 um3). Lo mismo ocurre con los núcleos celulares: 130,0 um3 en las glándulas anteriores y 202,3 um3 en las posteriores. Las células secretoras de las glándulas linguales sintetizan producto rico en proteínas y mucopolisacáridos neutros, pudiendo caracterizarse como seromucoso. Las células caliciformes de las superficies dorsal y ventral secretan proteínas y mucopolisacáridos neutros, clasificándose como del tipo G1, mientras que las células de sostén de las glándulas superficiales de las papilas fungiformes secretan moco rico en mucopolisacáridos neutros, sulfomucinas y sialomucinas.

The dorsal surface of the tongue of the bullfrog, Rana catesbeiana, has simple columnar epithelium with a few ciliated cells and goblet cells. The entire surface is covered with numerous filiform papillae and few fungiform. Filiform papillae have a simple columnar epithelium with secretory cells, while the fungiform have a sensory disc on their upper surface the lined by a stratified columnar epithelium with basal, peripheral, glandular and receptor cells. Over the dorsal lingual surface there are numerous winding tubular glands, which penetrate deeply into the muscle of the tongue, mingling with the fibers. The gland epithelium is cylindrical with secretory and supporting cells. The first are absolute on the basis of the gland and the latter are rare in the upper third. The ventral surface of the tongue is lined by a stratified epithelium, with the presence of goblet cells, with ciliated cells among them. Morphometrically, lingual glands varies in length, according to their location: shorter in the anterior region of the tongue (330 um) than in the posterior region (450 um). Secretory cells of the anterior lingual glands are smaller (1457.7 mm3) than the posterior ones (2645.9 um3). The same can be said of the cell nuclei, 130.0 um3 for the anterior glands and 202.3 um3 for the posterior ones. Secretory cells of the lingual glands contain substances rich in protein and neutral mucopolysaccharides, which characterize the seromucous type. Goblet cells of the dorsal and ventral surface epithelia secrete neutral mucopolysaccharides and proteins, and can be characterized as type G1 cells, and the supporting cells of the superficial glands of the fungiform papillae secrete a mucus rich in neutral mucopolysaccharides, sulfomucins and sialomucins.

The importance of glucose for the freezing tolerence/intolerence of the anuran amphibians Rana catesbeiana and Bufo paracnemis

Several species of terrestrially hibernating frogs, turtles and inserts have developed mechanisms, such as increased plasma glucose, anti-freeze proteins and antioxidant enzymes that resist to freezing, for survival at subzero temperatures. In the present study, we assessed the importance of glucose to cryoresistance of two anuran amphibians: the frog Rana catesbeiana and the toad Bufo paracnemis. Both animals were exposed to -2 degrees Celsius for measurements of plasma glucose levels, liver and muscle glycogen content, haematocrit and red blood cell volume. Frogs survived cold exposure but toads did not. Blood glucose concentration increased from 40.35 + 7.25 to 131.87 + 20.72 mg/dl (P < 0.01) when the frogs were transferred from 20 to -2 degrees Celsius. Glucose accumulation in response to cold exposition in the frogs was accompanied by a decrease (P < 0.05) in liver glycogen content from 3.94 + 0.42 to 1.33 + 0.36 mg/100 mg tissue, indicating that liver carbohydrate reserves were probably the primary carbon source of glucose synthesis whereas muscle carbohydrate seems unimportant. In the toads, the cold-induced hyperglycaemia was less (P < 0.05) pronounced (from 27.25 + 1.14 to 73.72 + 13.50 mg/dl) and no significant change could be measured in liver or muscle glycogen. Cold exposition had no effect on the haematocrit of the frogs but significantly reduced (P < 0.01) the haematocrit of toads from 20.0 + 2.1 per cent to 5.8 + 1.7 per cent due to a decreased red blood cell volume (from 1532 + 63 70 728 + 87 mm3). When toads were injected with glucose, blood glucose increased to levels similar to those of frogs and haematocrit did not change, but this failed to make them cryoresistent. In conclusion, the lack of cold-induced glucose catabolism may not be the only mechanism responsible for the freeze intolerance of Bufo paracnemis, a freeze-intolerant species.

Cardiovascular, respiratory and metabolic responses to temperature and hypoxia of the winter frog Rana catesbeiana

The objective of the present study was to determine the effects hypoxia and temperature on the cardiovascular and respiratory systems tems and plasma glucose levels of the winter bullfrog Rana calesbeiana. Body temperature was maintained at 10, 15, 25 and 35 degrees Celsius for measments of breathing frequency, heart rate, arterial blood pressure metabolic rate, plasma glucose levels, blood gases and acid-base status. Reducing body temperature from 35 to 10 degrees Celsius decreased (P<0.001) heart rate (bpm) from 64.0 ñ 3,1 (N =5) to 12.5 + 2.5 (N = 6) and blood pressure (mmHg) (P<0.05) from 41.9 ñ 2.1 (N = 5) to 33.1 ñ 2.1 (N = 6), whereas no significant changes were observed under hypoxia. Hypoxia-induced changes in breathing frequency and acid-base status were proportional to body ternperature, being pronounced at 25 degrees Celsius less so at l5 degrees Celsius, and absent at 10 degrees Celsius. Hypoxia at 35 degrees Celsius was lethal. Under normoxia, plasma glucose concentration (mg/dl) decreased (P<0.01 from 53.0 ñ 3.4 (N = 6) to 35.9 ñ 1.7 (N = 6) at body temperatures 35 and 10 degrees Celsius, respectively. Hypoxia had no significant effect on plasma glucose concentration at 10 and 15 degrees Celsius, but a 25 degrees Celsius there was a significant increase under conditions of 3 per cent inspired O2. The arterial PO2 and pH values were similar to those reported in previous studies on non-estivating Rana calesbeiana, but PaCO2 (37.5 ñ 1.9 mmHg, N = 5) was 3-fold higher, indicating increased plasma bicarbonate levels. The estivating bullfrog may be exposed not only to low temperatures but also to hypoxia. These animals show temperature-dependent responses that may be beneficial since during low body temperatures but also to hypoxia. These animals show temperature-dependent responses that may be beneficial since during low body temperatures the sensitivity of most physiological systems to hypoxia is reduced.

Estudio comparativo de la audición por potenciales provocados auditivos del tallo cerebral, en anfibios, reptiles, aves y mamíferos / Comparative study of hearing by brainstem auditory evoked responses on amphibians, reptiles, birds and mammals

Este trabajo compara, mediante potenciales provocados auditivos del tallo cerebral (PEAT), las diferencias funcionales entre especies que representan cuatro grupos taxonómicos de vertebrados terrestres (Anfíbios, reptiles, aves y mamíferos). Se observaron dos ondas, de mayor latencia en Rana catesbeina, cuatro en el Sceloporus torcuatus, cuatro de latencia corta en Columba livia, y siete en humanos con una latencia relativamente mayor. Los umbrales aduditivos descienden conforme se avanza en la escala filogenética

Leveduras associadas à porçäo terminal do intestino grosso de rana catresbeiana, shaw (1802), em diferentes fases de crescimento / Yeast associated with the terminal portion or large intestine of rana catesbiana, Shaw (1802), at defferent growth stage

Resumo: foram estudadas as porçöes terminais do intestino grosso de 64 räs da especie Rana catesbeiana criadas em confinamento. Esses animais foram separados em quatro fases distintas de crescimento, tendo sido alimentadoscom três tipos de raçäo. Foram isoladas 129, estirpes de leveduras identificadas através de métodos baseados em características macroiscópicas e fisiológicas, totalizando 35 estirpes identificadas em 24 espécies. Dentre as leveduras encontradas destacam-se as do gênero Candida pela frequência de isolamento sendo a espécie Candida rugosa a mais frequêntemente isolada nas quatro fases de cresciemnto, sugerindo tratar-se de levedura potencialmente patogênicas para o homem, bem como a importância da transiçäo do ambiente estritamente aquático para o terrestre, como provável fator de significado ecológico, responsável pela composiçäo da qualidadeda microbiota leveduriforme do trato alimentar destes animais (au)