Search results for "VIPER"
showing 10 items of 23 documents
Evaluating the potential for evolutionary mismatch in Batesian mimics: A case study in the endangered smooth snake (Coronella austriaca)
2018
Many harmless organisms gain a survival advantage by mimicking venomous species. This is the case of the endangered smooth snake (Coronella austriaca), which mimics venomous vipers. Although this may protect the smooth snake against most of its natural predators, it may render them at greater risk of mortality from humans, who are more inclined to kill species, such as vipers, that they consider dangerous. This may cause an evolutionary mismatch, whereby humans may counteract the natural advantage of mimicry. We explore this possibility of evaluating the willingness of humans to kill smooth snakes versus the adder (Vipera berus), as well as their ability to discern them in the Åland Islands…
Feedback Regulation of Syk by Protein Kinase C in Human Platelets
2019
The spleen tyrosine kinase (Syk) is essential for immunoreceptor tyrosine-based activation motif (ITAM)-dependent platelet activation, and it is stimulated by Src-family kinase (SFK)-/Syk-mediated phosphorylation of Y352 (interdomain-B) and Y525/526 (kinase domain). Additional sites for Syk phosphorylation and protein interactions are known but remain elusive. Since Syk S297 phosphorylation (interdomain-B) was detected in platelets, we hypothesized that this phosphorylation site regulates Syk activity via protein kinase C (PKC)-and cyclic adenosine monophosphate (cAMP)-dependent pathways. ADP, the GPVI-agonist convulxin, and the GPIb&alpha
Feodālisma problēmas Baltijā
1988
Rakstu problemātika ir daudzveidīga un aptver visu feodālisma vēstures laikmetu Baltijā. Krājumā ietverti ari avotpētnieciska (par Sakša Gramatiķa "Gesta Danorum") un historiogrāfiska (par R.Viperu) rakstura darbi.
Endothelin receptors mediating contraction in goat cerebral arteries
1993
1. The aim of the present study was to identify the subtype of receptor mediating contraction to endothelin-1 and sarafotoxin S6b in goat isolated middle cerebral arteries. 2. Endothelin-1, endothelin-2 and endothelin-3 contracted cerebral arteries in a concentration-dependent manner. Although the three peptides were full agonists, the order of potency was endothelin-1 = endothelin-2 > endothelin-3, with a relative potency of endothelin-1 and endothelin-2 versus endothelin-3 of approximately 280. Sarafotoxin S6b induced concentration-dependent contractions with lower potency than endothelin-1/endothelin-2, higher potency than endothelin-3 and a higher maximum response than the three endothe…
Ophiophagy in Coronella austriaca: first case of predation on Hierophis viridiflavus and first direct observations of predation on Vipera aspis
2020
We describe some cases of ophiophagy behaviour in Coronella austriaca
Variation in predator species abundance can cause variable selection pressure on warning signaling prey
2012
Predation pressure is expected to drive visual warning signals to evolve toward conspicuousness. However, coloration of defended species varies tremendously and can at certain instances be considered as more camouflaged rather than conspicuous. Recent theoretical studies suggest that the variation in signal conspicuousness can be caused by variation (within or between species) in predators' willingness to attack defended prey or by the broadness of the predators' signal generalization. If some of the predator species are capable of coping with the secondary defenses of their prey, selection can favor reduced prey signal conspicuousness via reduced detectability or recognition. In this study…
Snake venom disintegrins: evolution of structure and function.
2005
Disintegrins represent a family of polypeptides present in the venoms of various vipers that selectively block the function of integrin receptors. Here, we review our current view and hypothesis on the emergence and the structural and functional diversification of disintegrins by accelerated evolution and the selective loss of disulfide bonds of duplicated genes. Research on disintegrins is relevant for understanding the biology of viper venom toxins, but also provides information on new structural determinants involved in integrin recognition that may be useful in basic and clinical research. The role of the composition, conformation, and dynamics of the integrin inhibitory loop acting in …
Evolution of Snake Venom Disintegrins by Positive Darwinian Selection
2008
PII-disintegrins, cysteine-rich polypeptides broadly distributed in the venoms of geographically diverse species of vipers and rattlesnakes, antagonize the adhesive functions of beta(1) and beta(3) integrin receptors. PII-disintegrins evolved in Viperidae by neofunctionalization of disintegrin-like domains of duplicated PIII-snake venom hemorrhagic metalloproteinase (SVMP) genes recruited into the venom proteome before the radiation of the advanced snakes. Minimization of the gene (loss of introns and coding regions) and the protein structures (successive loss of disulfide bonds) underpins the postduplication divergence of disintegrins. However, little is known about the underlying genetic …
NMR Solution Structure of the Non-RGD Disintegrin Obtustatin
2003
The solution structure of obtustatin, a novel non-RGD disintegrin of 41 residues isolated from Vipera lebetina obtusa venom, and a potent and selective inhibitor of the adhesion of integrin alpha(1)beta(1) to collagen IV, has been determined by two-dimensional nuclear magnetic resonance. Almost the whole set of chemical shifts for 1H, 13C and 15N were assigned at natural abundance from 2D homonuclear and heteronuclear 500 MHz, 600 MHz and 800 MHz spectra at pH 3.0 recorded at 298 K and 303 K. Final structural constraints consisted of 302 non-redundant NOE (95 long-range, 60 medium, 91 sequential and 56 intra-residue), four disulfide bond distances, five chi1 dihedral angles and four hydroge…
Concerted motions of the integrin-binding loop and the C-terminal tail of the non-RGD disintegrin obtustatin.
2003
Obtustatin is a potent and selective inhibitor of the alpha1beta1 integrin in vitro and of angiogenesis in vivo. It possesses an integrin recognition loop that harbors, in a lateral position, the inhibitory 21KTS23 motif. We report an analysis of the dynamics of the backbone and side-chain atoms of obtustatin by homonuclear NMR methods. Angular mobility has been calculated for 90 assigned cross-peaks from 22 off-resonance rotating frame nuclear Overhauser effect spectroscopy spectra recorded at three magnetic fields. Our results suggest that the integrin binding loop and the C-terminal tail display concerted motions, which can be interpreted by hinge effects. Among the integrin-binding moti…