Xenopus skin mucus induces oral dyskinesias that promote escape from snakes

Barthalmus, George T.; Zielinski, William J.

doi:10.1016/0091-3057(88)90126-8

Cited by 30 publications

(10 citation statements)

References 19 publications

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“…Subsequently, the in vitro effects of NmU may not represent the actual physiological function. Previous studies have demonstrated that the secretion of the African clawed frog, Xenopus laevis, promotes yawning and other orofacial movements in several predatory snakes, which slowed ingestion rate and facilitated escape of the frog (43,44). Cerulein, as well as the myoactive and neuromodulatory peptide, xenopsin, were reported to be responsible for some of these antipredator actions (42).…”

Section: Discussionmentioning

confidence: 99%

Isolation, Structural Characterization, and Bioactivity of a Novel Neuromedin U Analog from the Defensive Skin Secretion of the Australasian Tree Frog, Litoria caerulea

Salmon¹,

Johnsen²,

Bienert³

et al. 2000

Journal of Biological Chemistry

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We report the isolation of a novel bioactive peptide, neuromedin U-23 (NmU-23), from the defensive skin secretion of the Australasian tree frog, Litoria caerulea. The primary structure of the peptide was established by a combination of microsequencing, mass spectroscopy and site-directed antiserum immunoreactivity as SDEEVQVPGGVISNGYFLFRPRN-amide (M r 2580.6). A synthetic replicate of frog NmU-23 displaced monoradioiodinated rat NmU-23 from uterine membranes in a dose-dependent fashion indistinguishable from nonisotopically labeled rat NmU-23. In a rat uterine smooth muscle strip preparation, synthetic frog NmU-23 produced dose-dependent contractions identical to porcine NmU-25. However, in a preparation of human urinary bladder muscle strip, the synthetic frog peptide was more potent than porcine NmU-25 in eliciting contraction and produced desensitization of the preparation to the latter peptide. This report demonstrates that the defensive skin secretion of a frog contains a novel peptide exhibiting a high degree of primary structural similarity to the endogenous vertebrate peptide, NmU, and that this frog skin analog displays biological activity in mammalian tissues.

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Section: Discussionmentioning

confidence: 99%

Isolation, Structural Characterization, and Bioactivity of a Novel Neuromedin U Analog from the Defensive Skin Secretion of the Australasian Tree Frog, Litoria caerulea

Salmon¹,

Johnsen²,

Bienert³

et al. 2000

Journal of Biological Chemistry

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“…Whereas the cellular origin of xenopsin in the frog is the exocrine granular gland of the dorsal skin (Sadler et al 1992), the cellular source of xenin has remained unknown (Feurle 1998). Amphibian xenopsin is localized in elliptical storage granules in the lumen of an exocrine skin cell and is secreted to the skin surface (Gibson et al 1986;Giovannini et al 1987) in defense against predators (Barthalmus and Zielinski 1988), whereas xenin appears to be a regulatory peptide secreted into the bloodstream and acting as a hormone. Xenin plasma concentrations increase in the peripheral circulation after food intake (Feurle et al 1992) and after pharmacological stimulation (Stoschus et al 1998).…”

mentioning

confidence: 99%

Localization of Xenin-immunoreactive Cells in the Duodenal Mucosa of Humans and Various Mammals

Anlauf

Weihe

Hartschuh

et al. 2000

J Histochem Cytochem.

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Xenin is a 25-amino-acid peptide extractable from mammalian tissue. This peptide is biologically active. It stimulates exocrine pancreatic secretion and intestinal motility and inhibits gastric secretion of acid and food intake. Xenin circulates in the human plasma after meals. In this study, the cellular origin of xenin in the gastro-entero-pancreatic system of humans, Rhesus monkeys, and dogs was investigated by immunohistochemistry and immunoelectron microscopy. Sequence-specific antibodies against xenin detected specific endocrine cells in the duodenal and jejunal mucosa of all three species. These xenin-immunoreactive cells were distinct from enterochromaffin, somatostatin, motilin, cholecystokinin, neurotensin, and secretin cells, and comprised 8.8% of the chromogranin A-positive cells in the dog duodenum and 4.6% of the chromogranin A-positive cells in human duodenum. In all three species, co-localization of xenin was found with a subpopulation of gastric inhibitory polypeptide (GIP)-immunoreactive cells. Immunoelectron microscopy in the canine duodenal mucosa demonstrated accumulation of gold particles in round, homogeneous, and osmiophilic secretory granules with a closely adhering membrane of 187 ± 19 nm diameter (mean ± SEM). This cell type was found to be identical to the previously described canine GIP cell. Immunocytochemical expression of the peptide xenin in a subpopulation of chromogranin A-positive cells as well as the localization of xenin immunoreactivity in ultrastructurally characterized secretory granules permitted the identification of a novel endocrine cell type as the cellular source of circulating xenin.

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“…Two primary types of skin glands are present in amphibians: mucous glands and granular glands. Granular gland secretions of extremely stressed X. laevis are reported to produce a milky secretion that caused gaping and yawning in snakes attempting to feed on the frogs (Barthalmus and Zielinski, 1998); this thick, milky secretion forms glutinous strands and has been reported to be toxic to the frogs themselves (Tinsley, 2010). Granular glands synthesize and secrete a variety of compounds that protect against predators, as well as chemicals that have antibacterial and antifungal properties.…”

Section: Integumentary Systemmentioning

confidence: 99%