Showing papers on "Toad published in 2008"

Immunolocalization of a mammalian aquaporin 3 homolog in water-transporting epithelial cells in several organs of the clawed toad Xenopus laevis

Abstract: Nucleotide sequences of cDNA were used to construct antibodies against an aquaporin (AQP) expressed in the clawed toad, Xenopus laevis, viz., Xenopus AQP3, a homolog of mammalian AQP3. Xenopus AQP3 was immunolocalized in the basolateral membrane of the principal cells of the ventral skin, the urinary bladder, the collecting duct and late distal tubule of the kidney, the absorptive epithelial cells of the large intestine, and the ciliated epithelial cells of the oviducts. Therefore, we designated this AQP as basolateral Xenopus AQP3 (AQP-x3BL). The intensity of labeling for AQP-x3BL differed between the ventral and dorsal skin, with the basolateral membrane of the principal cells in the ventral skin showing intense labeling, whereas that in the dorsal skin was lightly labeled. AQP-x3BL was also immunolocalized in the basolateral membrane of secretory cells in the small granular and mucous glands of the skin. As AQP-x5, a homolog of mammalian AQP5, is localized in the apical membrane of these same cells, this provides a pathway for fluid secretion by the glands. Although Hyla AQP-h2 is translocated from the cytoplasm to the apical membrane of the Hyla urinary bladder in response to arginine vasotocin (AVT), AQP-h2 immunoreactivity in Xenopus bladder remains in the cytoplasm and barely moves to the apical membrane, regardless of AVT stimulation. AQP-x3 is localized in the basolateral membrane, even though the AVT-stimulated AQP-h2 does not translocate to the apical membrane. These findings provide new insights into AQP function in aquatic anurans.

Neurally-derived nitric oxide regulates vascular tone in pulmonary and cutaneous arteries of the toad, Bufo marinus

Abstract: In this study, the role of nitric oxide (NO) in regulation of the pulmocutaneous vasculature of the toad, Bufo marinus was investigated. In vitro myography demonstrated the presence of a neural NO ...

Characterization of in vivo metabolites of toad venom using liquid chromatography-mass spectrometry.

Abstract: The structures of in vivo metabolites of marinobufotoxin (marinobufagin 3-suberoylarginine ester), marinobufagin, or bufalin which are typical components of toad venom widely used as the traditional Chinese drug, Ch'an Su, are confirmed using authentic samples based on their liquid chromatography-mass spectrometric behavior. A rat is orally administered 2 mg of the previously mentioned components of toad venom, the serum is collected 30 min after the administration, extracted, and then characterized. Marinobufotoxin is hydrolyzed and further epimerized into 3-epimarinobufagin, but marinobufagin 3-hemisuberate is not detected. After the administration of marinobufagin, 3-epimarinobufagin is detected in both the male and female rats, but marinobufagin 3-sulfate is formed only in the female rats. Bufalin is metabolized to 3-epibufalin, which is found to undergo further conjugation resulting in its 3-glucuronide. Furthermore, 3-epibufalin 3-sulfate is formed only in the female rats.

A Case of Pulmonary Cryptococcosis in a Free-living Toad (Bufo bufo)

Abstract: Pulmonary cryptococcosis was observed in a free-living adult female common toad (Bufo bufo) that was killed by a vehicle. Both lungs had various eosinophilic, monomorphic, and spherical to elliptical organisms identified as Cryptoccocus spp. The yeasts were demonstrated by Grocott's silver method and the periodic acid-Schiff reaction and the capsule was positive for mucin with a mucicarmine stain. The agent was confirmed by immunohistochemistry, using the monoclonal antibody anti-Cryptococcus neoformans, and by a polymerase chain reaction-based method using a C. neoformans-specific primer. This report, to the best of our knowledge, represents the first case of cryptococcosis in a common toad.

The Identification of the Sex Chromosome and Karyotype of Four Toad Species (Genus Bufo) in Thailand by T-lymphocyte Cell Culture

Abstract: Our knowledge is the first report on karyotypic study of four toad species (genus Bufo) in Thailand namely; large-eared toad (Bufo macrotis Boulenger 1887), Indochinese dwarf toad (Bufo parvus Boulenger 1887), common Indian toad (Bufo melanostictus Schneider 1799) and river giant toad (Bufo asper Gravenhorst 1829). Blood samples were taken from 5 males and 5 females of each four toad species. After the standard whole blood T-lymphocyte culture in the presence of colchicine, the metaphase spreads were performed on microscopic slides and air-dried. Conventional staining, G-banding and C-banding techniques were applied to stain the chromosomes. The results indicated 2n=22 and fundamental number (NF) 44 in both male and female of four toad species. The autosomes of B. macrotis and B. melanostictus is being as 18 metacentric and 4 submetacentric chromosomes while B. parvus and B. asper is as 16 metacentric and 6 submetacentric chromosomes. G-banding technique showed a B. melanostictus's constriction on short arm of Y chromosome (the largest chromosome) but did not show on X chromosome. C-banding technique demonstrated a dark band constriction on Y chromosome of B. melanostictus, the representative of constitutive heterochromatin. However, there is no dark band constriction on X chromosome. So, we conclude that the sex determination of B. melanostictus is XY system. Although we do not treat B. macrotis, B. parvus and B. asper with G-banding and C-banding technique, we also predict that those three species have the same sex determination as B. melanostictus. We extremely appreciate to public our present research, the first cytogenetic study of B. macrotis and B. asper.

Biotransformation of maximakinin, a bradykinin-related nonadecapeptide from toad venom, by mammalian kallikrein and salivary proteases

Abstract: Maximakinin is an N-terminally extended bradykinin (DLPKINRKGPRPPGFSPFR) from the venom of a Chinese toad (Bombina maxima) that displays highly selective activity at mammalian arterial smooth muscle receptors. In this study, we report that incubation of maximakinin with either kallikrein or human saliva generates catabolites with enhanced bioactivity that retain the tissue selective effects of the parent molecule. In addition, we have observed that kallikrein rapidly cleaves the C-terminal arginyl residue of both maximakinin and bradykinin – a cleavage hitherto considered to be performed by a carboxypeptidase that facilitates selective bradykinin receptor targeting. Maximakinin has thus evolved as a ‘smart’ defensive weapon in the toad with inherent resistance to the signal-terminating protease hardware in the potential predator. Thus, natural selection of amphibian skin peptides for antipredator defence, through interspecies delivery by an exogenous secretory mode, produces subtle structural stabilization modifications that can potentially provide new insights for the design of orally active and selectively targeted peptide therapeutics.

Effect of Extraction from Toad Cake,Toad-cortex and Bufonic on ATP Enzyme of Myocardium Membrane

Abstract: The experiment studied the influence on the activity of Na+-K+-ATPase,Ca2+-ATPase and Mg2+-Ca2+-ATPase in myocardium membrane of the mouse by the extracts of toad cake,toad-cortex and toad-ecdysis,in the meantime cinobufagin was applied as control.The results indicated that all extracts could repress the cardiac muscle cell membrane of above-mentioned three species ATP enzymatic activities.The liposoluble extracts of toad cake and toad-cortex had stronger inhibition action of Na+-K+-ATPase than other extracts.The influence effects of the Ca2+-ATPase and Mg2+-Ca2+-ATPase were similar.The action of water soluble of toad-cortex and cinobufagin revealed stronger than that of other extracts.