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Toad
About: Toad is a research topic. Over the lifetime, 1624 publications have been published within this topic receiving 28732 citations.
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TL;DR: Chromaffin cells in the interrenal gland of clawed toad were studied by a combination of fluorescence histochemistry and electron microscopy and it was found that there existed a third type of chromAffin cells which emitted a primary catecholamine fluorescence.
Abstract: Chromaffin cells in the interrenal gland of clawed toad (Xenopus laevis) were studied by a combination of fluorescence histochemistry and electron microscopy. Microspectrofluorometrical analyses indicated that there were adrenaline(A)-containing and noradrenaline(NA)-containing chromaffin cells, both of which were scattered within the interrenal tissue. In addition, it was found that there existed a third type of chromaffin cells which emitted a primary catecholamine fluorescence. This cell type could be identified electron microscopically as small granule chromaffin (SGC) cells, based on the size of secretory granules (100nm in diameter) which were considerably smaller than those that of NA (200nm) or of A (250nm) cells.
TL;DR: A series of bufadienolides were isolated from the Bufo viridis toad venom, and their cytotoxic activities against three human cancer cell lines (HeLa, HT-29, MCF7) and a non-cancer cell line (L-O2) were explored using the MTT assay in vitro as mentioned in this paper .
TL;DR: The results indicate that visual cues alone do not elicit any apparent defensive response, suggesting that tadpoles mainly rely on chemical cues to assess predation risk.
Abstract: Simple Summary Tadpoles are known to use their sense of smell to detect the presence of predators, but some studies showed their reliance on vision during social interaction, suggesting that vision might have a role in predatory contexts as well. Here, we investigated how chemical or visual cues of a native predator, or a combination of both, influence the defensive behaviour of green toad tadpoles. We expected tadpoles to reduce their activity when exposed to chemical cues and avoid the area of the experimental arena near to the caged predator when exposed to the visual ones. With both cues, we expected tadpoles to show both responses and with greater intensity. Our results indicate that visual cues alone do not elicit any apparent defensive response, suggesting that tadpoles mainly rely on chemical cues to assess predation risk. Abstract The anti-predator behaviour of green toad (Bufotes balearicus) tadpoles was investigated by exposing them to only the visual or chemical cues, or a combination of both, of a native predator, southern hawker Aeshna cyanea. We collected green toad egg strings in the field and tadpoles did not receive any predatory stimulus before the onset of the experiment. To manipulate chemical and visual cues independently, dragonfly larvae were caged inside a transparent plastic container, while chemical cues (odour of tadpole-fed dragonfly larvae) were injected into the surrounding arena. An empty container and water were used, respectively, as controls. The behaviour of individually tested tadpoles was videorecorded for 40 min, of which 20 were before their exposure to stimuli. Five second-distance frames were compared to assess both tadpole activity and position within the arena with respect to the visual stimulus. The tadpole level of activity strongly decreased after exposure to either chemical cues alone or in combination with visual cues, while visual cues alone apparently did not elicit any defensive response. The position of tadpoles inside the arena was not affected by visual cues, suggesting that green toad tadpoles mainly rely on olfactory cues to assess the level of predation risk.
TL;DR: This paper conducted a simple experiment to evaluate response learning in a primitive anuran species, the common midwife toad (Alytes obstetricans) under an appetitive stimulus.
Abstract: Studies of response learning of amphibians are scarce compared to other vertebrates. We conducted a simple experiment to evaluate response learning in a primitive anuran species, the common midwife toad (Alytes obstetricans) under an appetitive stimulus. We hypothesized that, despite the primitive character of the studied species, the animals would be able to rapidly associate a particular arm of a basic T-shaped experimental arena with the reward, and that the existing male parental care of the species would provide males greater cognitive abilities than females. The response obtained by 12 males and 13 females was statistically different than such expected by chance, suggesting a learning process. The sex of the animal, as well as the average time spent to select the correct choice, were key during the learning process. Contrary to expectations, females showed higher learning capacities than males, perhaps as a consequence of the elaborate mate selection process and the competition between females to access males in this group of amphibians. The obtained results indicate that a rapid learning capacity is highly conservative in the phylogeny, having evolved from early tetrapods to those existing today in reptiles, birds, and mammals.