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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: 2',5'-Dideoxyadenosine, an inhibitor of cAMP production, blocked the increase in SCC produced by PGI2, suggesting that the effects of this compound on SCC are mediated via cAMP.
Abstract: The effects of prostaglandins of the E series on sodium and water transport have been studied extensively. PGE2 has been shown to inhibit the increase in osmotic water flow produced by vasopressin and to stimulate short-circuit current (SCC) in the toad bladder. On the other hand, the effects of prostacyclin (PGI2), an arachidonic acid product, on sodium and water transport have not been extensively evaluated. The present studies describe the effects of PGI2 on basal and vasopressin-stimulated osmotic water flow and on SCC in the urinary bladder of the toad. Studies were performed in the absence or presence of indomethacin. PGI2 in the absence of indomethacin had no effect on basal or vasopressin-stimulated osmotic water flow. When indomethacin was present, thereby eliminating intrinsic prostaglandin biosynthesis, PGI2 inhibited basal but not vasopressin-stimulated osmotic water flow. PGI2 increased SCC in the presence or absence of indomethacin. 6-keto PGF1 alpha, the stable metabolite of PGI2, had no effect on SCC. PGI2 stimulated cAMP production in isolated toad bladder epithelial cells. 2',5'-Dideoxyadenosine, an inhibitor of cAMP production, blocked the increase in SCC produced by PGI2, suggesting that the effects of this compound on SCC are mediated via cAMP.
7 citations
03 Jun 1981
7 citations
TL;DR: The results show that fertilization does not trigger a phospholipid transport process catalyzed by lipid transfer proteins, and imply that the supernatants of unfertilized oocytes may not be essential for toad embryo development, and do not rule out, however, that a phosphatidylcholine-specific lipid transfer protein could be required for embryo early growth.
7 citations
TL;DR: The results suggest that the alien toad is a potential threat to the novel amphibian predators on Hokkaido, although they also imply that the novel predators on Sapporo have the potential to develop toxin resistance through adaptive evolution.
Abstract: To manage biological invasions effectively, the impacts of alien species on the demography and traits of native species must be known, but determining those impacts can be challenging. We used a comparative approach to gain insight into the impacts that an alien toad (Bufo japonicus formosus) might have on native Japanese predatory amphibians. We compared the susceptibility of native predator species to alien toad toxins in the alien‐invaded range and the susceptibility of closely related native predator species to the toxins in the alien toad's native range to investigate the impacts of an alien on a native species. Bufo japonicus formosus is native to Honshu, but was recently introduced to Hokkaido and Sado. In laboratory experiments, we compared individual mortality of predators exposed to a toad hatchling between novel predators on the toad‐invaded islands and ecologically similar congeneric or conspecific species on Honshu, where the toad is native. We also compared (1) the percentage of individuals that consumed a toad hatchling and (2) toxin resistance (i.e. survival and growth of individuals after toad consumption) between these two groups of predators, as mechanistic components behind the susceptibility of the predators to the toxic prey. The mortality of Rana pirica from all populations after consumption of a toad hatchling was almost 100%, and that of Hynobius retardatus ranged from 14 to 90%, depending on the population. In contrast, the mortality of Rana ornativentris and Hynobius nigrescens was near 0% regardless of population. These differences between congeneric predators were mostly due to differences in their toxin resistance. These results suggest that the alien toad is a potential threat to the novel amphibian predators on Hokkaido, although they also imply that the novel predators on Hokkaido have the potential to develop toxin resistance through adaptive evolution. However, this counteradaptation may have a higher chance of evolving in H. retardatus than in R. pirica because of differences in their genetic backgrounds.
7 citations
TL;DR: It is suggested that aldosterone influences potassium transport in the toad bladder via DNA-dependent RNA synthesis and that the effect of the hormone on potassium and sodium may be in some way related.
Abstract: The effect of aldosterone on potassium uptake by the toad bladder is described. The hormone stimulated the uptake of potassium across the serosal border of the bladder. The increased uptake was the consequence of an increase in the rate of potassium influx. An effect on potassium uptake was characterized by a latent period of approximately 60 min; it was evident for periods as long as 5 h, and it was abolished by addition of actinomycin D. The time course of the aldosterone effect on potassium closely resembled the effect of the hormone on sodium transport. It is suggested that aldosterone influences potassium transport in the toad bladder via DNA-dependent RNA synthesis. In addition, it is suggested that the effect of the hormone on potassium and sodium may be in some way related.
7 citations