positive darwinian selection results in resistance to cardioactive toxins in true toads (anura: bufonidae).members of the family bufonidae, true toads, are famous for their endogenously synthesized cardioactive steroids that serve as defensive toxins. evolution of resistance to these toxins is not understood. we sequenced a key region of the toxin's binding site in the na(+)/k(+) atpase for relevant taxa representing hyloidea (including bufonids), ranoidea and archaeobatrachia and tested for positive selection in a phylogenetic context. bufonidae were distinct from other hyloidea at 4-6 of 12 sites a ...200919465576
alkaloids in bufonid toads (melanophryniscus): temporal and geographic determinants for two argentinian species.bufonid toads of the genus melanophryniscus represent one of several lineages of anurans with the ability to sequester alkaloids from dietary arthropods for chemical defense. the alkaloid profile for melanophryniscus stelzneri from a location in the province of córdoba, argentina, changed significantly over a 10-year period, probably indicating changes in availability of alkaloid-containing arthropods. a total of 29 alkaloids were identified in two collections of this population. eight alkaloids ...200717333373
ultrastructural characteristics of the lung of melanophryniscus stelzneri stelzneri (weyenberg, 1875) (anura, bufonidae).the lung of the toad, melanophryniscus stelzneri stelzneri was studied using scanning and transmission electron microscopy. in m.s.stelzneri the parenchyma forms a polygonal network arrangement, therefore the parenchyma is edicular. these spaces are delimited by the interconnection of third order septa which are covered by respiratory epithelium. small patches of ciliated epithelium without goblet cells appear irregularly distributed on the septa. the respiratory epithelium consists of one type ...200212625309
serous gland dimorphism in the skin of melanophryniscus stelzneri (anura: bufonidae).two serous gland types (i and ii) in the skin of the argentine toad melanophryniscus stelzneri were discovered using light and electron microscopy. glands of the two types differ in several traits: features of the products (both mature and immature), organelles involved in biosynthesis, and paths of serous maturation. no consistent differences, however, were detected between the myoepithelial sheaths encircling the secretory units. type i glands manufacture vesicles containing a single dense bod ...19989642789
alkaloids from bufonid toads (melanophryniscus): decahydroquinolines, pumiliotoxins and homopumiliotoxins, indolizidines, pyrrolizidines, and quinolizidines.skins of bufonid toads of the genus melanophryniscus contain several classes of alkaloids: decahydroquinolines, pumiliotoxins, allopumiliotoxins, homopumiliotoxins, both 3,5- and 5,8-disubstituted indolizidines, 3,5-disubstituted pyrrolizidines, and a 1,4-disubstituted quinolizidine. tricyclic alkaloids, including precoccinelline [193a] and alkaloid 236, an oxime methyl ether, are present in one population of melanophryniscus stelzneri.19938482947
the diversity and evolution of locomotor muscle properties in anurans.anuran jumping is a model system for linking muscle physiology to organismal performance. however, anuran species display substantial diversity in their locomotion, with some species performing powerful leaps from riverbanks or tree branches, while other species move predominantly via swimming, short hops or even diagonal-sequence gaits. furthermore, many anurans with similar locomotion and morphology are actually convergent (e.g. multiple independent evolutions of 'tree frogs'), while closely r ...201627707867
dietary alkaloid sequestration in a poison frog: an experimental test of alkaloid uptake in melanophryniscus stelzneri (bufonidae).several lineages of brightly colored anurans independently evolved the ability to secrete alkaloid-containing defensive chemicals from granular glands in the skin. these species, collectively referred to as 'poison frogs,' form a polyphyletic assemblage that includes some species of dendrobatidae, mantellidae, myobatrachidae, bufonidae, and eleutherodactylidae. the ability to sequester alkaloids from dietary arthropods has been demonstrated experimentally in most poison frog lineages but not in ...201324190023
neuroepithelial bodies in the lung of melanophryniscus stelzneri stelzneri (anura, bufonidae).electron microscopy of the lungs of melanophryniscus stelzneri stelzneri (anura) revealed the presence of a complex pattern of corpuscular cells (ccs). the respiratory surface over the septa presents small areas where the ccs are grouped forming neuroepithelial bodies (nebs). these corpuscular structures can also be localized in the inner layer of the lung wall. although in both cases nebs protrude slightly into the airway lumen, they are separated from the airway lumen and the basal connective ...200314639477
further report of the occurrence of tetrodotoxin in atelopus species (family: bufonidae).in alcoholic extracts from museum samples of the toads atelopus subornatus and a. peruensis tetrodotoxin and its analogues, 4-epitetrodotoxin and 4,9-anhydrotetrodotoxin were detected by fluorometric hplc analysis, extending the list of amphibians containing this toxin. however, the toxin was not detected in samples of melanophryniscus stelzneri, dendrophryniscus minutus and oreophrynella sp.19957597728
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