Academic literature on the topic 'Anura Physiology'

For the fi rst time information on helminths of the Fire-bellied toad Bombina bombina (Linnaeus, 1761)from natural biocoenoses of in Saratov region is given. In 2012, 24 specimens of amphibians from the Medveditsa River fl oodplain in the vicinity of the Atkarsk city were examined by full helminthological autopsy. A total of 6 helminth species from two classes were registered: Trematoda (5) and Chromadorea (1). All helminth species for the given host are registered for the fi rst time in the studied region. A parasite specifi c to Bombina, the trematode Pneumonoeces variegatus abbreviatus (Rudolphi, 1819) [=Haematoloechus abbreviatus (Bychowsky, 1932)], was found. The helminth community structure is complex: biohelminthes (trematodes) dominate; nematodes are represented by a single species from the geohelminth group. High host infestation with metacercariae Tylodelphys excavata (Rudolphi, 1803) and Paralepoderma cloacicola (Luhe, 1909) is characteristic. Peculiarities of composition, structure and infestation of helminths are explained by peculiarities of biology, ecology and probably physiology of the host.

We postulated that as a hibernating species, frogs might have variable demands for nutrients at different seasons of the year and that this must be reflected in seasonal variations of physiologic processes related to nutrient transport and absorption. We examined the rate of mucus transport on the ciliated palate and the movement of nutrients across the intestinal lumen of leopard frogs, Rana pipiens. Mucus transport on the frog palate was strongly influenced by season, with maximal transport occurring in late June (Julian day 178, p = 0.0001; r = 0.58). This increased transport rate was associated with a summertime increase in mucus recoil (lower tangent δ) and a decrease in mucus hydration (increase in percent solids composition). Intestinal transport of leucine, lysine, and galactose did not appear to exhibit seasonal variability. These data suggest that different mechanisms may operate in determining seasonal variability in physiologic responses.Key words: mucociliary clearance, mucus viscoelasticity, intestinal absorption, Anura, seasonal variation.

Amphibians are susceptible to environmental pollutants and these compounds influence the development, morphology, physiology, behavior, and reproduction of these animals. Escherichia coli is common in aquatic habitats of frogs and could also damage their reproductive activity. Thus, our objective was to evaluate the effects of E. coli lipopolysaccharide on the testes of Eupemphix nattereri after 2, 6, 12, and 24 hours. As in other anurans, the testes of E. nattereri are paired structures and spermatogenesis into the locule is cystic, with mast cells in the interstitial region as well as testicular melanocytes. The administration of lipopolysaccharide decreased the absolute locular volume after 12 h while increasing the interstitial volume. In addition, lipopolysaccharide treatment decreased the absolute volume of all cell types in animals analyzed after 12 h. The amount of mast cells in the interstitial region increased after 12 h of inoculation. Acute exposure to lipopolysaccharide clearly alters testicular morphology, decreasing the volume of both locular and germ cells. However, acute treatment did not impair spermatogenesis and after 24 h, the treatment effects were minimized. Thus, this study was the first to demonstrate that lipopolysaccharide is a potential agent for causing damage to the testes of anurans.

Entender a ecologia alimentar de anuros é essencial para compreender a biologia de vida destes animais. Essas informações fornecem dados necessários sobre seu habitat, morfologia, fisiologia e comportamento. Nesse sentido objetivou-se analisar a dieta de uma população Leptodactylus macrosternum, da fazenda Cajueiro, município de Catolé do Rocha, Sertão paraibano. As coletas ocorreram mensalmente entre os meses de outubro de 2013 e junho de 2014, realizadas por meio de busca ativa auditiva/visual. Em laboratório, verificou- se os conteúdos alimentares até o nível taxonômico de Ordem. Foram identificadas 10 categorias alimentares, sendo sete pertencentes à classe Insecta, duas Arachinida e uma Gasthropoda, além de vegetais e terra/pedra. Os principais itens alimentares na dieta, segundo o Índice de Importância Alimentar, foram Coleoptera e Hymenoptera, seguidos de Odonata, Hemiptera e Orthoptera, não ocorrendo de modo geral modificações significativas no consumo dos itens alimentares. As alterações no consumo dos itens na dieta de L. macrosternum, possivelmente resultam da disponibilidade, associada a variações pluviométricas da região. Diet of Leptodactylus macrosternum (Amphibia Anura: Leptodactylidae) in the backlands of Paraiba, BrazilAbstract: Understanding the frogs food ecology is essential to understand the biology of life of these animals. This information provides necessary data on their habitat, morphology, physiology and behavior. In the study we analyzed the diet of a Leptodactylus macrosternum population, of the farm Cajueiro, city of Catolé do Rocha, wilderness region of Paraíba. The gatherings were executed between October of 2013 and June of 2014, by hearing/visual active search. In the laboratory, the food contents were analyzed in the taxonomic categories of Order. Were identified 10 feeding categories, being 7 belonging to the class Insecta, 2 Arachinida, 1 Gasthropoda, in addition to vegetables and ground/rock. The main food items in the diet, according to the Index of Alimentary Importance, were Coleoptera and Hymenoptera, followed by Odonata, Hemiptera and Orthoptera, generally not occurring significant changes in the consumption of the food items. Changes in the consumption of items in L. macrosternum diet possibly result from the availability, associated with variations in rainfall in the region.

Abstract Evolutionary changes towards a miniaturized body plan may directly affect other important phenotypic traits related to the physiology, behaviour and ecology of organisms. The frog genus Brachycephalus is an outstanding example of a radiation of miniaturized species endemic to the Brazilian Atlantic Forest. We inferred ancestral states and historical changes in body size, body colour and hyperossification to test hypotheses about diversification and selective environmental mechanisms leading to the evolution of these specialized traits. The ancestral distribution was associated with high-elevation regions in the northern Serra do Mar mountain range, and diversification in the genus was coincident with important geological and climatic events during the history of the Atlantic Forest. The dynamic historical changes provided an opportunity for multiple lowland lineages and for speciation via dispersal and vicariance in multiple invasions of the highlands. The ancestral Brachycephalus was reconstructed as miniaturized and dull coloured, without hyperossification in the skin, skull or postcranial skeleton. A parallel evolution of phenotypic traits has occurred in northern and southern Atlantic Forest lineages, beginning in the Miocene. Shifts in body size are not related to elevation range or latitude. However, we found a significant correlation between the evolution of hyperossification and aposematism with increasing body size.

The importance of hypovolemia in dehydrational death was assessed in two anuran species. Xenopus laeyis, a species which experiences a significant reduction in circulating plasma volume with dehydration, was used to evaluate the role of sympathetic reflex compensation in hypovolemia. Adrenergic blockade with propranolol or phenoxybenzamine produced no significant reduction in dehydration tolerance in this species, although β-blockade with propranolol appeared to have a minor effect. The role of hypovolemic shock in the terminal circulatory collapse that precedes death in dehydrating anurans was investigated in the toad, Bufo marinus. The activity of lysosomal proteinases (cathepsins) was used as an indicator of the shock state. An assay was developed for the determination of cathepsin activity in toad plasma and was used to demonstrate the presence of proteinases similar in pH dependence to mammalian cathepsins Bl and D. Plasma cathepsin D-type activity increased with dehydration in toads but was not significantly different from the activity in controls or in toads subjected to splanchnic artery occlusion. Toads appear to maintain plasma volume to 20% water loss at the expense of other extracellular fluids. These results do not support the hypothesis that hypovolemia is a direct cause of dehydrational death in anurans.

Orientador: Denis Otavio Vieira de Andrade
Banca: Braz Titon Junior
Banca: Guilherme Gomes
Resumo: Devido à alta permeabilidade da pele e a ectotermia, anfíbios terrestres são confrontados por compromissos envolvendo o balanço de água e a regulação da temperatura corpórea. O modo como tais compromissos são acomodados, sobre uma extenção de temperaturas e estados de hidratação, influencia importantemente o comportamento e a ecologia desses animais. Nesse contexto, usando o anfíbio terrestre Rhinella schneideri como organismo modelo, os objetivos do presente estudo foram duplos. Primeiramente, nós determinamos como a sensibilidade termal de uma característica ecologicamente relevante - a locomoção - é afetada pela desidratação. Além disso, nós examinamos os efeitos dos mesmos níveis de desidratação na preferência termal e na tolerância termal. A medida que a desidratação se torna mais severa, as temperaturas ótimas para o desempenho locomotor diminuíram e a amplitude de temperaturas para um desempenho próximo ao máximo se estreitou. Semelhantemente, a desidratação foi acompanhada por uma diminuição da amplitude de tolerância termal. Tal declínio foi causado pelo aumento da temperatura crítica mínima e pela diminuição da temperatura crítica máxima, com este último mudando de modo mais acentuado. Em geral, nossos resultados mostram que os efeitos negativos da desidratação no desempenho comportamental e na tolerância termal são, ao menos parcialmente, amenizados pelo simultâneo ajuste na preferência termal. Nós discutimos algumas potenciais implicações dessa observação para a ... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Due to their highly permeable skin and ectothermy, terrestrial amphibians are challenged by compromises between water balance and body temperature regulation. The way in which such compromises are accommodated, under a range of temperatures and dehydration levels, impact importantly the behavior and ecology of amphibians. Thus, using the terrestrial toad Rhinella schneideri as a model organism, the goals of the present study were two-fold. First, we determined how the thermal sensitivity of a centrally relevant trait - locomotion - was affected by dehydration. Secondly, we examined the effects of the same levels of dehydration on thermal preference and thermal tolerance. As dehydration becomes more severe, the optimal temperature for locomotor performance was lowered and performance breadth narrower. Similarly, dehydration was accompanied by a decrease in the thermal tolerance range. Such a decrease was caused by both, an increase in the critical minimal temperature and a decrease in the thermal maximal temperature, with the latter changing more markedly. In general, our results show that the negative effects of dehydration on behavioral performance and thermal tolerance are, at least partially, counteracted by concurrent adjustments in thermal preference. We discuss some of the potential implications of this observation for the conservation of anuran amphibians
Mestre

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O tamanho do alimento e a temperatura corpórea são dois fatores que reconhecidamente influenciam a resposta metabólica pós-prandial dos vertebrados ectotérmicos. Leptodactylus latrans é uma espécie generalista que consome desde invertebrados até pequenos vertebrados, de forma que sua dieta é composta por itens de tamanho variável, os quais sempre são ingeridos inteiros. A temperatura corpórea de L. latrans está sujeita a disponibilidade de nichos térmicos adequados nos ambientes onde ocorre, os quais são possivelmente explorados através da termorregulação comportamental. No presente estudo, nós avaliamos os efeitos do tamanho da presa e da temperatura corpórea sobre a resposta metabólica pós-prandial, em indivíduos adultos da rã-manteiga, Leptodactylus latrans (Anura, Leptodactylidae) através da quantificação das taxas de consumo de oxigênio antes e após a alimentação. A resposta metabólica pós-prandial de L. latrans pode ser caracterizada por um rápido aumento nas taxas de consumo de oxigênio logo após a ingestão do alimento, até atingir valores máximos entre 85,93 ± 9,92 e 224,54 ± 26,08 mLO2.kg-1. h-1, dentro de 1-2 dias. Após este pico, houve um retorno paulatino da taxa metabólica aos níveis de jejum entre 3 a 7 dias após a alimentação. De maneira geral, encontramos que a ingestão de presas maiores causa um maior incremento metabólico e aumenta a duração da digestão. Já o incremento da temperatura é acompanhado pela diminuição da duração da digestão às expensas de taxas metabólicas pós-prandiais mais elevadas. Tanto em um caso como no outro, não encontramos indicações de que fatores cardiorrespiratórios pudessem atuar na limitação do tamanho da presa ou na temperatura na qual a digestão pode ocorrer. No entanto, é plausível que outros fatores de cunho ecológico sejam relevantes na consideração dos efeitos do tamanho do alimento e da temperatura na digestão de L. latrans. Em especial, um maior retorno energético absoluto ao se alimentar de presas maiores e a diminuição do tempo de digestão em temperaturas mais elevadas, ambos aspectos documentados em L. latrans, podem representar benefícios ecológicos importantes.
Meal size and body temperature affect markedly the post-prandial metabolic response of ectothermics vertebrates. Leptodactylus latrans is a generalist anuran species feeding on diverse prey itens, from invertebrates to small vertebrates, with considerable size variation and that are always ingested whole. The body temperature of L. latrans is largely dependent of the availability of thermal niches in the environment, which are possibly explored by means of behavioral thermoregulation. In the present study, we investigated the effects of meal size and body temperature on the post-prandial metabolic response of adults of the Neotropical leptodatylid frog, Leptodactylus latrans (Anura, Leptodactylidae) by quantifying the rates of oxygen consumption before and after meal ingestion. The post-prandial metabolic response of L. latrans can be characterized by the rapid increase in the rates of oxygen consumption shortly after meal ingestion, until reach peak between 85,93 ± 9,92 e 224,54 ± 26,08 mLO2.kg-1. h-1, within 1-2 days post-feeding. Thereafter, metabolism gradually return to the pre-feeding values within 3 to 7 days post-feeding. In general, we found that the ingestion of larger meals were followed by greater metabolic increment and by longer digestion duration. Temperature increment caused digestion duration to decrease at the expenses of greater post-prandial metabolic rates. In both cases, we did not found evidences that cardiorespiratory compromises could limit meal size or the temperature in which meal digestion could occur. On the other hand, some ecological considerations seems to be relevant in considering the effects of meal size and body temperature on the digestion of L. latrans. More specifically, the greater gross energetic gain when feeding on larger prey and the shortening of digestion duration at higher temperatures, both observed in L. latrans, are likely to yield substantial ecological advantages.
Capes Demanda Social

In this study, I looked at the effects of sound level, temperature and dehydration/hypernatremia on the brainstem auditory evoked potential (BAEP) of four species of anuran amphibians (Rana pipiens, Rana catesbeiana, Bufo americanus and Bufo terrestris). The BAEP was used because it allowed me to monitor both the peripheral and central aspects of auditory nervous function simultaneously and over a long period of time.

This project examined the role of the cytoskeleton in regulatory mechanisms of the amiloride-sensitive Na⁺ channels in isolated frog skin epithelium. The epithelium from ventral frog skin is a model tissue which has proved significant in our understanding of the basic principles involved in water and Na⁺ homeostasis. In particular, this project examines ways in which local (non-hormonal) and hormonal regulatory mechanisms adjust the Na⁺ permeability of apical membranes of frog skin epithelium. Both mechanisms contain factors that are known to increase the apical membrane Na⁺ permeability mainly by increases in the number of open channels. The origin of these new open channels is unknown but, it is postulated that they could arise either by activation of quiescent channels already present in the apical membrane, or by recruitment of channels from cytoplasmic stores. Regarding the latter hypothesis, we also examined the idea that the cytoskeleton might somehow be involved in the insertion of Na⁺ channels within vesicles, into the apical membrane. This is based on the fact that the cytoskeleton is involved in a similar mechanism whereby, in the toad urinary bladder, anti-diuretic hormone (ADH) causes the insertion of aggregates with water channels. Much current interest focuses on the role of the cytoskeleton in the regulation of epithelial Na⁺ channels. To test this hypothesis, we used noise analysis to examine the effects of disrupting the cytoskeleton, on two different mechanisms which bring about changes in open channel densities. The mechanisms are: (1) lowering mucosal Na⁺ concentration (non-hormonal), and (2) addition of arginine-vasopressin (A VP) (hormonal). Non-hormonal, autoregulatory changes in apical membrane Na⁺ conductance were examined by investigating the effects of reducing the mucosal Na⁺ concentration. Our results showed that lowering the mucosal Na⁺ concentration induced large increases in the open channel density in order to stabilise the transport rate. In addition, we observed an average 55-60% increase in the open channel probability, which implies that in epithelium from Rana fuscigula, changes of channel open probability are also an important mechanism in the autoregulation of channel densities in response to a reduction in mucosal Na⁺. The hormonal control of Na⁺ channels by A VP has been intensively studied by noise analysis and the patch clamp. Our results confirmed previous reports that A VP increases the Na⁺ transport rate by increasing the number of open Na⁺ channels, primarily through large changes in the total number of channels, without a significant change in open probability. Regarding the role of the cytoskeleton in regulation of Na⁺ channels and/or its possible role in control of inserting putative vesicles with Na⁺ channels, we studied the effects of disrupting the cytoskeleton on the two regulatory mechanisms. Disrupting microtubules with colchicine had no, or very little effect on either of the regulatory mechanisms. On the other hand, the integrity of the microfilaments was very important for the autoregulatory changes in the number of open channels. After cytochalasin B treatment, lowering the mucosal Na⁺ concentration did not result in the usual compensatory changes in channel densities. There was no prior evidence that cytochalasin B had any actual effect on the F-actin network in the frog skin epithelium. Accordingly, modified cytochemical techniques were designed to demonstrate and localise F-actin in the epithelial granular cells. The direct immunofluorescent method proved useful, but did not allow sufficient resolution to examine the changes to different populations of actin in the cells. We then modified an immunogold method to suit our conditions, and the results demonstrated the localisation of different pools of F-actin and showed the effects of the cytochalasin B and vasopressin.

Two Australian frogs were introduced to New Zealand over 100 years ago. Since their introduction they have become widespread and well established with Litoria ewingii being more prevalent in alpine and cooler areas of New Zealand, while Litoria raniformis is found in more temperate coastal areas. Very little physiological data exists for these frogs and aside from their distribution not much is known about them in New Zealand. Thus the effects of thermal acclimation and temperature change on respiration and locomotion were examined in these two exotic frogs. The more terrestrial and alpine dwelling L. ewingii was found to be able to thermally acclimate its respiration performance, where respiration was highest when acclimation temperature matched test temperature. It was also able to thermally acclimate its locomotory performance, jumping significantly further at lower temperatures, however, acclimation to high temperatures impacted its jump performance at cold temperatures. The frog L. raniformis was found to only be able to thermally acclimate its respiration and locomotion to high temperatures, as performance at low temperatures was often poor. The data shows that L. ewingii is a cold temperate frog rather than a warm habitat frog, while L. raniformis is an animal adapted to warm temperatures. From this we can begin to see the effect that temperature has on the physiology of these two exotic frogs and the major role that temperature may be playing in driving the differences seen in the distribution of these two species in New Zealand.