The Experts below are selected from a list of 2814 Experts worldwide ranked by ideXlab platform
Marcelo R V Diniz - One of the best experts on this subject based on the ideXlab platform.
-
lachesis muta viperidae cdnas reveal diverging pit viper molecules and scaffolds typical of cobra Elapidae venoms implications for snake toxin repertoire evolution
Genetics, 2006Co-Authors: Inacio L M Junqueiradeazevedo, Ana T C Ching, Eneas Carvalho, Fernanda Faria, Milton Y Nishiyama, Paulo Lee Ho, Marcelo R V DinizAbstract:Efforts to describe toxins from the two major families of venomous snakes (Viperidae and Elapidae) usually reveal proteins belonging to few structural types, particular of each family. Here we carried on an effort to determine uncommon cDNAs that represent possible new toxins from Lachesis muta (Viperidae). In addition to nine classes of typical toxins, atypical molecules never observed in the hundreds of Viperidae snakes studied so far are highly expressed: a diverging C-type lectin that is related to Viperidae toxins but appears to be independently originated; an ohanin-like toxin, which would be the third member of the most recently described class of Elapidae toxins, related to human butyrophilin and B30.2 proteins; and a 3FTx-like toxin, a new member of the widely studied three-finger family of proteins, which includes major Elapidae neurotoxins and CD59 antigen. The presence of these common and uncommon molecules suggests that the repertoire of toxins could be more conserved between families than has been considered, and their features indicate a dynamic process of venom evolution through molecular mechanisms, such as multiple recruitments of important scaffolds and domain exchange between paralogs, always keeping a minimalist nature in most toxin structures in opposition to their nontoxin counterparts.
Patrick David - One of the best experts on this subject based on the ideXlab platform.
-
global diversity of snakes serpentes reptilia in freshwater
Hydrobiologia, 2008Co-Authors: Olivier S. G. Pauwels, Van Wallach, Patrick DavidAbstract:A list of the snake species inhabiting freshwaters is provided. It includes 153 species, which represents about 5% of all known snakes. These freshwater snakes belong to 44 genera distributed among the families Acrochordidae, Boidae, Colubridae, Elapidae, Homalopsidae and Viperidae. The highest diversities in freshwater snakes are found in the Oriental (64 species) and Neotropical (39 species) Regions. Conservation actions are needed for several overcollected species with a limited distribution.
Steve Sorota - One of the best experts on this subject based on the ideXlab platform.
-
Cobra (Naja spp. ) Nicotinic Acetylcholine Receptor Exhibits Resistance to Erabu Sea Snake (Laticauda semifasciata) Short-Chain α-Neurotoxin
Journal of Molecular Evolution, 2004Co-Authors: Zoltan Takacs, Kirk C. Wilhelmsen, Steve SorotaAbstract:Snake α-neutotoxins of Elapidae venoms are grouped into two structural classes, short-chain and long-chain α-neutotoxins. While these two classes share many chemical and biological characteristics, there are also distinct dissimilarities between them, including their binding site on the nicotinic acetylcholine receptor (nAChR), specificity among species of Chordata, and the associated pharmacological effects. In the present study we test the hypothesis that structural motifs that evolved to confer natural resistance against conspecific long-chain α-neurotoxins in Elapidae snakes also interfere with the biological action of short-chain α-neurotoxins. We expressed functional nAChRs that contains segments or single residues of the Elapidae nAChR ligand binding domain and tested the effect of short-chain α-neurotoxin erabutoxin-a (ETX-a) from the Erabu sea snake Laticauda semifasciata on the acetylcholine-induced currents as measured by two-microelectrode voltage clamp. Our results show that the Elapidae nAChR α subunit segment T^154–L^208 ligand binding domain has an inhibitory effect on the pharmacological action of ETX-a. This effect is primarily attributed to the presence of glycosylation at position N^189. If the glycosylation is removed from the T^154–L^208 segment, the nAChR will be inhibited, however, to a lesser extent than seen in the mouse. This effect correlates with the variations in α-neurotoxin sensitivity of different species and, importantly, reflects the evolutionary conservation of the binding site on the nAChR polypeptide backbone per se. Phylogenetic analysis of α-neurotoxin resistance suggests that α-neurotoxin-resistant nAChR evolved first, which permitted the evolution of snake venom α-neurotoxins. A model describing α-neurotoxin resistance in Elapidae snakes is presented.
-
Snake α-Neurotoxin Binding Site on the Egyptian Cobra (Naja haje) Nicotinic Acetylcholine Receptor Is Conserved
Molecular biology and evolution, 2001Co-Authors: Zoltan Takacs, Kirk C. Wilhelmsen, Steve SorotaAbstract:Evolutionary success requires that animal venoms are targeted against phylogenetically conserved molecular structures of fundamental physiological processes. Species producing venoms must be resistant to their action. Venoms of Elapidae snakes (e.g., cobras, kraits) contain alpha-neurotoxins, represented by alpha-bungarotoxin (alpha-BTX) targeted against the nicotinic acetylcholine receptor (nAChR) of the neuromuscular junction. The model which presumes that cobras (Naja spp., Elapidae) have lost their binding site for conspecific alpha-neurotoxins because of the unique amino acid substitutions in their nAChR polypeptide backbone per se is incompatible with the evolutionary theory that (1) the molecular motifs forming the alpha-neurotoxin target site on the nAChR are fundamental for receptor structure and/or function, and (2) the alpha-neurotoxin target site is conserved among Chordata lineages. To test the hypothesis that the alpha-neurotoxin binding site is conserved in Elapidae snakes and to identify the mechanism of resistance against conspecific alpha-neurotoxins, we cloned the ligand binding domain of the Egyptian cobra (Naja haje) nAChR alpha subunit. When expressed as part of a functional Naja/mouse chimeric nAChR in Xenopus oocytes, this domain confers resistance against alpha-BTX but does not alter responses induced by the natural ligand acetylcholine. Further mutational analysis of the Naja/mouse nAChR demonstrated that an N-glycosylation signal in the ligand binding domain that is unique to N. haje is responsible for alpha-BTX resistance. However, when the N-glycosylation signal is eliminated, the nAChR containing the N. haje sequence is inhibited by alpha-BTX with a potency that is comparable to that in mammals. We conclude that the binding site for conspecific alpha-neurotoxin in Elapidae snakes is conserved in the nAChR ligand binding domain polypeptide backbone per se. This conclusion supports the hypothesis that animal toxins are targeted against evolutionarily conserved molecular motifs. Such conservation also calls for a revision of the present model of the alpha-BTX binding site. The approach described here can be used to identify the mechanism of resistance against conspecific venoms in other species and to characterize toxin-receptor coevolution.
Richard Shine - One of the best experts on this subject based on the ideXlab platform.
-
phylogenetic relationships within laticaudine sea snakes Elapidae
Molecular Phylogenetics and Evolution, 2011Co-Authors: Amanda Lane, Richard ShineAbstract:Abstract The sea snake subfamily Laticaudinae consists of a single genus with eight named species, based on morphological characters. We used microsatellite and mitochondrial DNA (mtDNA) data to clarify the adaptive radiation of these oviparous sea snakes in the South Pacific, with special reference to New Caledonia and Vanuatu. A mitochondrial DNA data set (ND4 gene 793 bp) was obtained from 345 individuals of the five species of Laticauda sp. sea snakes endemic to the region. Maximum likelihood and Bayesian approaches yielded the same optimal tree topology, identifying two major clades (yellow-banded and blue-banded sea snakes). Although all laticaudine sea snakes rely on small islands as oviposition sites, the two lineages differ in their use of marine vs. terrestrial habitats. A highly aquatic species ( Laticauda laticaudata ) shows a strong pattern of genetic isolation by distance, implying that the patchy distribution of terrestrial habitats has had little impact on gene flow. The more terrestrial clade ( Laticauda colubrina , Laticauda frontalis , Laticauda guineai , Laticauda saintgironsi ) shows stronger geographic differentiation in allelic frequencies, associated with island groups rather than with geographic distance. Microsatellites and mtDNA suggest that L. frontalis (restricted to Vanuatu) represents a recent founder-induced speciation event, from allopatric migrants of the New Caledonian taxon L. saintgironsi . A major divergence in speciation patterns between the two major clades of laticaudine snakes thus correlates with (and perhaps, is driven by) differences in the importance of terrestrial habitats in the species’ ecology.
Ryan W Matika - One of the best experts on this subject based on the ideXlab platform.
-
Carbon monoxide inhibits hemotoxic activity of Elapidae venoms: potential role of heme
BioMetals, 2018Co-Authors: Vance G Nielsen, Nathaniel Frank, Ryan W MatikaAbstract:Envenomation by hemotoxic enzymes continues to be a major cause of morbidity and mortality throughout the world. With regard to treatment, the gold standard to abrogate coagulopathy caused by these venoms is still the administration of antivenom; however, despite antivenom therapy, coagulopathy still occurs and recurs. Of interest, this laboratory has demonstrated in vitro and in vivo that coagulopathy inducing venom derived from snakes of the family Viperidae exposed to carbon monoxide (CO) is inhibited, potentially by an attached heme. The present investigation sought to determine if venoms derived from snakes of the Elapidae family (taipans and cobras) could also be inhibited with CO or with the metheme inducing agent, O -phenylhydroxylamine (PHA). Assessing changes in coagulation kinetics of human plasma with thrombelastography, venoms from Elapidae snakes were exposed in isolation to CO (five species) or PHA (one specie) and placed in human plasma to assess changes in procoagulant or anticoagulant activity. The procoagulant activity of two taipan venoms and anticoagulant activity of three cobra venoms were significantly inhibited by CO. The venom of the inland taipan was also inhibited by PHA. In sum, these data demonstrate indirectly that the biometal heme is likely bound to these disparate venoms as an intermediary modulatory molecule. In conclusion, CO may not just be a potential therapeutic agent to treat envenomation but also may be a potential modulator of heme as a protective mechanism for venomous snakes against injury from their own proteolytic venoms.