Showing papers on "Toad published in 2017"

Microbiome-Mediated Biotransformation of Cane Toad Bufagenins.

Abstract: Cane toads are an invasive pest species in which all life stages employ cardiotoxic bufagenins as a chemical defense against predators. Curiously, the bufagenin profiles of eggs and tadpoles are more complex than those of parotoid secretion, the principle mechanism of toxin delivery in adult toads. In an effort to understand this complexity, we determined that selected strains of adult toad parotoid-gland-associated Gram-positive bacteria, Bacillus spp., were capable of biotransforming secreted bufagenins, marinobufagenin (1), telocinobufagenin (2), bufalin (3), and resibufagenin (4), to hydroxylated scaffolds commonly encountered in cane toad eggs and tadpoles. Scaled-up cultivation, preparative chromatography, and detailed spectroscopic analysis identified Bacillus sp. CMB-TD29 biotransformation products of 1, as 11α-hydroxymarinobufagenin (6), 12β-hydroxymarinobufagenin (7), and 17α-hydroxymarinobufagenin (8). Comparative bufagenin profiles across the cane toad life cycle suggest that bacterial biotransformation mediates the oxidative adaptation of adult toad bufagenins to hydroxylated bufagenins encountered in eggs and tadpoles. We speculate that knowledge of a relationship between the cane toad microbiome and bufagenin chemical defenses could inspire the development of a natural, nontoxic, environmentally sustainable bacterial biocontrol for this toxic invasive species.

Isolation and identification of L/D-lactate-conjugated bufadienolides from toad eggs revealing lactate racemization in amphibians

Abstract: Three pairs of bufadienolide l/d-lactate epimers (1-6) were isolated from the eggs of the toad Bufo bufo gargarizans. The structures were elucidated by using spectroscopic methods, X-ray diffraction analysis and a modified Mosher's method. Compounds 1-6 represent the first occurrence of lactate-conjugated bufadienolides in nature, and illustrate the existence of an enzyme-controlled epimerization from l- to d-lactate in amphibians. The biosynthetic pathways, in which two key enzymes might be involved (i.e., lactate racemase and acyltransferase), were proposed. In addition, the biological assays revealed that compounds 1-4 are potent cytotoxic agents against human gastric cancer cells BGC-823 and human lung cancer cells A549 with IC50 values in a range of 8.0 to 80.0 nM.

Bufalin, a bufanolide steroid from the parotoid glands of the Chinese toad, suppresses hERG K + currents expressed in HEK293 cells.

Abstract: In this study, we investigated the effect of bufalin on the human ether-a-go-go-related gene (hERG) K+ channels using the perforated patch recording technique. We measured a half-maximal inhibitory concentration (IC50 ) of 24.83 μM and maximal inhibitory effect of 39.45 ± 1.14% with bufalin. These findings suggest that bufalin is a potent hERG K+ channel blocker and may provide a new way for understanding Chan Su-induced arrhythmia.

N-methyl serotonin analogues from the Bufo bufo toad venom interact efficiently with the α7 nicotinic acetylcholine receptors.

Abstract: Two low-molecular-weight compounds were isolated from the parotid gland secret of the toad Bufo bufo, which by absorption spectra and HPLC-MS/MS chromatography data correspond to di- and trimethyl derivatives of serotonin (5-hydorxytryptamine): bufotenine (confirmed by counter synthesis) and bufotenidine (5-HTQ). In experiments on competitive radioligand binding, these compounds showed a higher affinity and selectivity for neuronal α7 nicotinic acetylcholine receptors compared with the muscular cholinergic receptors. The most efficient compound in terms of binding value was bufotenine, the efficiency of 5-HTQ was an order of magnitude lower, and the minimal activity was exhibited by serotonin.

Molecular and Physiological Mechanisms of Toxin Resistance in Toad-Eating Snakes

Abstract: ...................................................................................................................... iii PUBLIC ABSTRACT .........................................................................................................v ACKNOWLEDGMENTS ................................................................................................ vii LIST OF TABLES ...............................................................................................................x LIST OF FIGURES .......................................................................................................... xii CHAPTER

Arginine derivatives of dicarboxylic acids from the parotid gland secretions of common toad Bufo bufo—New agonists of ionotropic γ-aminobutyric acid receptors

Abstract: Compounds activating γ-aminobutyric acid type A receptor were isolated from the toad Bufo bufo venom as a result of chromatographic separation. Analysis of the structure of these compounds by mass spectrometry and nuclear magnetic resonance showed that they are arginine derivatives of dicarboxylic acids and represent suberylarginine, pimeloylarginine, and adipoylarginine.

Toad stripping method

Abstract: The invention discloses a toad stripping method which comprises the following steps that a live toad is placed into a wine atmosphere, the toad is enabled to be in a semi-drunk state, adequate sodium chloride is sprayed for disinfection, feeding is not performed for 2-3 days, and the toad achieves clean excretion; stripping solutions are prepared: the stripping solutions include a No. 1 stripping solution and a No. 2 stripping solution, the mass ratio of the No. 1 stripping solution and the No. 2 stripping solution is 1:(3-5), the No. 1 stripping solution is applied to the live toad body, the stripping temperature is controlled to be at 25-32 DEG C, after 2-3 hours, the No. 2 stripping solution is sprayed to the live toad body, the live toad is placed into clean water with the temperature of 20-25 DEG C immediately until cracks occur to the toad cortex on the back of the live toad, the toad cortex falls naturally, and the toad cortex is clipped out from the toad mouth with pincers. The toad is in the semi-drunk state, rapid stripping is performed under the stimulation of the stripping solutions, the live toad is placed into the clean water immediately until the cracks occur to the toad cortex on the back of the live toad, the toad won't eat the stripped toad cortex in the water, and the completeness of the toad cortex is kept.

Toad tadpoles turn homegrown poisons on each other

Abstract: Young amphibians are the first animals thought to use toxins against rivals of their own species.