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mating systems, reproductive success, and sexual selection in secretive species: a case study of the western diamond-backed rattlesnake, crotalus atrox.long-term studies of individual animals in nature contribute disproportionately to our understanding of the principles of ecology and evolution. such field studies can benefit greatly from integrating the methods of molecular genetics with traditional approaches. even though molecular genetic tools are particularly valuable for species that are difficult to observe directly, they have not been widely adopted. here, we used molecular genetic techniques in a 10-year radio-telemetric investigation ...201424598810
snake venom glutaminyl cyclases: purification, cloning, kinetic study, recombinant expression, and comparison with the human enzyme.among various snake venom components, glutaminyl cyclase (vqc) is one of the least understood protein family and none of its members has been purified or characterized. here we confirmed the presence of vqc activity in a wide spectrum of venom species via enzymatic assay using a synthetic fluorogenic substrate. we have also cloned novel vqc cdnas from seven species including crotalus atrox. the results revealed more than 96% sequence similarities among vqcs and ∼75% sequence identities between v ...201424814012
use of medicinal fauna in mexican traditional medicine.mexico has great biodiversity of fauna. the use of fauna with medicinal properties is a common practice since pre-hispanic times. in the last decade, there has been an interest in ethnozoological studies in mexico. therefore, more studies are needed in order to gather information regarding the use of fauna with medicinal properties in méxico. ethnozoological studies are necessary in order to discover new medications for human health. this review presents current information in terms of ethnozool ...201424440438
skin lipid structure controls water permeability in snake molts.the role of lipids in controlling water exchange is fundamentally a matter of molecular organization. in the present study we have observed that in snake molt the water permeability drastically varies among species living in different climates and habitats. the analysis of molts from four snake species: tiger snake, notechis scutatus, gabon viper, bitis gabonica, rattle snake, crotalus atrox, and grass snake, natrix natrix, revealed correlations between the molecular composition and the structur ...201424157843
comparison of the protective effect of a commercially available western diamondback rattlesnake toxoid vaccine for dogs against envenomation of mice with western diamondback rattlesnake (crotalus atrox), northern pacific rattlesnake (crotalus oreganus oreganus), and southern pacific rattlesnake (crotalus oreganus helleri) venom.to evaluate effectiveness of a commercially available toxoid manufactured from western diamondback (wd) rattlesnake (crotalus atrox) venom against envenomation of mice with wd, northern pacific (np) rattlesnake (crotalus oreganus oreganus), and southern pacific (sp) rattlesnake (crotalus oreganus helleri) venom.201525710764
zebrin ii / aldolase c expression in the cerebellum of the western diamondback rattlesnake (crotalus atrox).aldolase c, also known as zebrin ii (zii), is a glycolytic enzyme that is expressed in cerebellar purkinje cells of the vertebrate cerebellum. in both mammals and birds, zii is expressed heterogeneously, such that there are sagittal stripes of purkinje cells with high zii expression (zii+), alternating with stripes of purkinje cells with little or no expression (zii-). the patterns of zii+ and zii- stripes in the cerebellum of birds and mammals are strikingly similar, suggesting that it may have ...201525692946
incipient speciation with biased gene flow between two lineages of the western diamondback rattlesnake (crotalus atrox).we used mitochondrial dna sequence data from 151 individuals to estimate population genetic structure across the range of the western diamondback rattlesnake (crotalus atrox), a widely distributed north american pit viper. we also tested hypotheses of population structure using double-digest restriction site associated dna (ddradseq) data, incorporating thousands of nuclear genome-wide snps from 42 individuals. we found strong mitochondrial support for a deep divergence between eastern and weste ...201525534232
problems with mitigation translocation of herpetofauna.mitigation translocation of nuisance animals is a commonly used management practice aimed at resolution of human-animal conflict by removal and release of an individual animal. long considered a reasonable undertaking, especially by the general public, it is now known that translocated subjects are negatively affected by the practice. mitigation translocation is typically undertaken with individual adult organisms and has a much lower success rate than the more widely practiced conservation tran ...201525040040
the deep origin and recent loss of venom toxin genes in rattlesnakes.the genetic origin of novel traits is a central but challenging puzzle in evolutionary biology. among snakes, phospholipase a2 (pla2)-related toxins have evolved in different lineages to function as potent neurotoxins, myotoxins, or hemotoxins. here, we traced the genomic origin and evolution of pla2 toxins by examining pla2 gene number, organization, and expression in both neurotoxic and non-neurotoxic rattlesnakes. we found that even though most north american rattlesnakes do not produce neuro ...201627641771
identification of lys49-pla2 from crude venom of crotalus atrox as a human neutrophil-calcium modulating protein.we fortuitously observed a human neutrophil intracellular free-calcium concentration ([ca(2+)]i) increasing activity in the commercially available phosphodiesterase i (pde i), which is actually dried crude venom of crotalus atrox. as this activity was not observed with another commercially available pure pde i, we tried to find out the causative molecule(s) present in 'crude' pde, and identified lys49-phospholipase a2 (lys49-pla2 or k49-pla2), a catalytically inactive protein which belongs to th ...201626937214
responses of infrared-sensitive tectal units of the pit viper crotalus atrox to moving objects.rattlesnakes perceive ir radiation with their pit organs. this enables them to detect and strike towards warm-blooded prey even in the dark. in addition, the ir sense allows rattlesnakes to find places for thermoregulation. animate objects (e.g., prey) tend to move and thus cause moving ir images across the pit membrane. even when an object is stationary, scanning head movements of rattlesnakes will result in moving ir images across the pit membrane. we recorded the neuronal activity of ir-sensi ...201626906281
iron and carbon monoxide attenuate degradation of plasmatic coagulation by crotalus atrox venom.hypofibrinogenemia is an important clinical consequence following envenomation by crotalus species, usually attenuated or prevented by administration of antivenom. it has been determined that iron and carbon monoxide (co) enhance fibrinogen as a thrombin substrate, likely secondary to conformational changes in molecular structure. we tested the hypothesis that pretreatment of plasma with iron and co could attenuate the effects of exposure to crotalus atrox venom. human plasma was exposed to 0 to ...201626575491
iron and carbon monoxide attenuate crotalus atrox venom-enhanced tissue-type plasminogen activator-initiated fibrinolysis.in addition to degrading fibrinogen as a source of consumptive coagulopathy, rattlesnake venom has also been demonstrated to enhance fibrinolysis and degrade alpha-2-antiplasmin. the goals of this investigation was to characterize the kinetic fibrinolytic profile of crotalus atrox venom in the absence and presence of tissue-type plasminogen activator (tpa), and to also ascertain if iron and carbon monoxide (co, a positive modulator of alpha-2-antiplasmin) could attenuate venom-enhanced fibrinoly ...201626575490
soluble p-selectin rescues viper venom-induced mortality through anti-inflammatory properties and psgl-1 pathway-mediated correction of hemostasis.venomous snakebites are lethal and occur frequently worldwide each year, and receiving the antivenom antibody is currently the most effective treatment. however, the specific antivenom might be unavailable in remote areas. snakebites by viperidae usually lead to hemorrhage and mortality if untreated. in the present study, challenges of rattlesnake (crotalus atrox) venom markedly increased the circulating soluble p-selectin (sp-sel) level, but not p-selectin (p-sel, selp(-/-)) mutants, in wild-ty ...201627779216
molecular cloning and characterization of cdnas encoding metalloproteinases from snake venom glands.snake venom metalloproteinases (svmps) are a superfamily of zinc-dependent proteases and participate in a number of important biological, physiological and pathophysiological processes. in this work, we simultaneously amplified nine cdnas encoding different classes of metalloproteinases from glands of four different snake species (agkistrodon contortrix laticinctus, crotalus atrox, crotalus viridis viridis and agkistrodon piscivorus leucostoma) by rt-pcr with a pair of primers. among the encoded ...201619799929
pathogenesis of hemorrhage induced by rattlesnake venom. an electron microscopic study.the pathogenesis of hemorrhage induced by rattlesnake (crotalus atrox) venom was investigated at the electron microscopic level. swiss-webster white mice were injected intramuscularly with one-fifth the ld(50) dose of whole venom. muscle samples were obtained by biopsy 2 minutes, 30 minutes and 3 hours after venom injection. capillaries in the endomysium were in various stages of degeneration. endothelial cells of damaged capillaries contained dilatated endoplasmic reticulum and perinuclear spac ...20164843388
evaluation of antimicrobial and antiviral activities of different venoms.animals' venomous secretions or peptides obtained from those secretions are used in the development of new therapeutic agents. the aims of this study were to investigate antimicrobial and antiviral activity of four different venoms obtained from the frog named bufo arenarum and the snakes crotalus atrox, causus rhombeatus and naja melanoleuca.201626743517
opossum peptide that can neutralize rattlesnake venom is expressed in escherichia coli.an eleven amino acid ribosomal peptide was shown to completely neutralize western diamondback rattlesnake (crotalus atrox) venom in mice when a lethal dose of the venom was pre-incubated with the peptide prior to intravenous injection. we have expressed the peptide as a concatenated chain of peptides and cleaved them apart from an immobilized metal affinity column using a protease. after ultrafiltration steps, the mixture was shown to partially neutralize rattlesnake venom in mice. preliminary e ...201727718338
iron protects porcine plasma coagulation kinetics from degradation by crotalus atrox venom.while the administration of antivenom to treat hemotoxic snake bite injury remains the gold standard of therapy, we have demonstrated that modifying human fibrinogen with iron and carbon monoxide renders it resistant to fibrinogenolytic snake venom enzymes. in order to translate these findings into a possible biometal-based therapy complementary to antivenom administration, a preclinical model that possesses fibrinogen that closely mimics the human molecule in response to iron and carbon monoxid ...201728726133
insight into the roles of selection in speciation from genomic patterns of divergence and introgression in secondary contact in venomous rattlesnakes.investigating secondary contact of historically isolated lineages can provide insight into how selection and drift influence genomic divergence and admixture. here, we studied the genomic landscape of divergence and introgression following secondary contact between lineages of the western diamondback rattlesnake (crotalus atrox) to determine whether genomic regions under selection in allopatry also contribute to reproductive isolation during introgression. we used thousands of nuclear loci to st ...201728616190
effects of purified human fibrinogen modified with carbon monoxide and iron on coagulation in rabbits injected with crotalus atrox venom.while snake venom derived enzymes, such as the thrombin-like activity possessing ancrod, have been used to treat thrombotic disease by defibrinogenating patients, the therapeutic potential of fibrinogenolytic snake venom enzymes, such as those derived from crotalus atrox, have not been fully explored. however, one of the potential risks of administering fibrinogenolytic enzymes to effect defibrinogenation is hemorrhage secondary to hypofibrinogenemia. the present investigation sought to determin ...201728889321
when less means more: dehydration improves innate immunity in rattlesnakes.immune function can vary based on availability of resources, and most studies of such influences have focused on the co-investment of energy into immune and other physiological functions. when energy resources are limited, trade-offs exist, which can compromise immunity for other functions. as with energy, water limitation can also alter various physiological processes, yet water has received little consideration for its possible role in modulating immune functions. we examined the relationship ...201728404727
crotalus atrox venom preconditioning increases plasma fibrinogen and reduces perioperative hemorrhage in a rat model of surgical brain injury.perioperative bleeding is a potentially devastating complication in neurosurgical patients, and plasma fibrinogen concentration has been identified as a potential modifiable risk factor for perioperative bleeding. the aim of this study was to evaluate preconditioning with crotalus atrox venom (cv-pc) as potential preventive therapy for reducing perioperative hemorrhage in the rodent model of surgical brain injury (sbi). c. atrox venom contains snake venom metalloproteinases that cleave fibrinoge ...201728102287
effect of iron and carbon monoxide on fibrinogenase-like degradation of plasmatic coagulation by venoms of four crotalus species.annually, thousands suffer poisonous snake bite, often from defibrinogenating species. iron and carbon monoxide (co) improve coagulation kinetics by modulation of fibrinogen as demonstrated in various agkistrodon species and crotalus atrox. thus, we sought to determine whether pretreatment of plasma with iron and co could attenuate venom-mediated catalysis of fibrinogen obtained from four common crotalus species with known fibrinogenase activity. human plasma was pretreated with ferric chloride ...201726845427
snake venom extracellular vesicles (svevs) reveal wide molecular and functional proteome diversity.proteins constitute almost 95% of snake venom's dry weight and are produced and released by venom glands in a solubilized form during a snake bite. these proteins are responsible for inducing several pharmacological effects aiming to immobilize and initiate the pre-digestion of the prey. this study shows that proteins can be secreted and confined in snake venom extracellular vesicles (svevs) presenting a size distribution between 50 nm and 500 nm. svevs isolated from lyophilized venoms collected ...201830104604
characterization of the rabbit as an in vitro and in vivo model to assess the effects of fibrinogenolytic activity of snake venom on coagulation.several in vitro investigations have demonstrated that anticoagulant effects of fibrinogenolytic snake venom metalloproteinases have been abrogated in human plasma by modifying fibrinogen with iron (fe) and carbon monoxide (co) to prevent catalysis or by directly inhibiting these enzymes with co. to translate these findings, we chose to assess the rabbit as a model of envenomation with crotalus atrox venom. it was determined with thrombelastography that 15 times the concentration of venom noted ...201828696521
crotalus atrox venom exposed to carbon monoxide has decreased fibrinogenolytic activity in vivo in rabbits.envenomation by haemotoxic enzymes remains a significant source of human morbidity and mortality worldwide, with administration of long-acting or multiple doses of antivenom first-line therapy. however, coagulopathy can still occur and recur. of interest, it has been recently demonstrated that direct, isolated exposure of snake venom enzymes with fibrinogenolytic activity to carbon monoxide (co) abrogates venom-mediated loss of coagulation in human plasma. these observations of co inhibition of ...201828691277
penetrating ocular injury by western diamondback rattlesnake. 201830119804
catroxmp-ii: a heme-modulated fibrinogenolytic metalloproteinase isolated from crotalus atrox venom.it has been recently demonstrated that the hemotoxic venom activity of several species of snakes can be inhibited by carbon monoxide (co) or a metheme forming agent. these and other data suggest that the biometal, heme, may be attached to venom enzymes and may be modulated by co. a novel fibrinogenolytic metalloproteinase, named catroxmp-ii, was isolated and purified from the venom of a crotalus atrox viper, and subjected to proteolysis and mass spectroscopy. an ion similar to the predicted sing ...201829761254
in vitro effects of crotalus atrox snake venom on chick and mouse neuromuscular preparations.the neuromuscular effect of venoms is not a major clinical manifestation shared between rattlesnakes native to the americas, which showed two different venom phenotypes. taking into account this dichotomy, nerve muscle preparations from mice and chicks were used to investigate the ability of crotalus atrox venom to induce in vitro neurotoxicity and myotoxicity. unlike crotalic venoms of south america, low concentrations of c. atrox venom did not result in significant effects on mouse neuromuscul ...201829604435
suspected anaphylaxis and lack of clinical protection associated with envenomation in two dogs previously vaccinated with crotalus atrox toxoid.to describe the clinical presentation of two canines present in anaphylactic shock secondary to rattlesnake envenomation. in both cases, there was no previous documented previous envenomation event and the initial sensitization required for anaphylactic response is believed to be secondary to crotalus atrox toxoid vaccine.201829248468
venom composition of adult western diamondback rattlesnakes (crotalus atrox) maintained under controlled diet and environmental conditions shows only minor changes.many species of snakes produce venom as a chemical means of procuring potentially fractious prey. studies have increasingly focused on venom compositional variation between and within individual snakes of the same species/subspecies, with significant differences often being observed. this variation in composition has been attributed to differences in age, season, diet, and environment, suggesting that these factors could help explain the inter- and intra-specific variation found in some snake ve ...201930954451
role of scale wettability on rain-harvesting behavior in a desert-dwelling rattlesnake.during storms in the southwestern united states, several rattlesnake species have been observed drinking rain droplets collected on their dorsal scales. this process often includes coiling and flattening of the snake's body, presumably to enhance water collection. here, we explored this rain-harvesting behavior of the western diamond-backed rattlesnake (crotalus atrox) from the perspective of surface science. specifically, we compared surface wettability and texture, as well as droplet impact an ...201931867507
rattlesnakes must drink: meal consumption does not improve hydration state.water is critical to survival, yet free-standing water is often rare in deserts and seasonally dry environments. thus, many dry-adapted species utilize either metabolic (that produced from metabolism) or dietary (that found in food) water to meet their hydric needs. it is suspected that desert reptiles can fulfill their hydric needs solely through dietary water intake. however, food consumption does not improve the hydration state of gila monsters (heloderma suspectum), a binge-feeding desert li ...201931135328
mechanisms underpinning the permanent muscle damage induced by snake venom metalloprotease.snakebite is a major neglected tropical health issue that affects over 5 million people worldwide resulting in around 1.8 million envenomations and 100,000 deaths each year. snakebite envenomation also causes innumerable morbidities, specifically loss of limbs as a result of excessive tissue/muscle damage. snake venom metalloproteases (svmps) are a predominant component of viper venoms, and are involved in the degradation of basement membrane proteins (particularly collagen) surrounding the tiss ...201930695027
the neutralization efficacy of expired polyvalent antivenoms: an alternative option.the expense of production and distribution of snakebite antivenom, as well as its relatively infrequent use, has caused antivenom to be increasingly difficult to obtain and ultimately producing an alarming global shortage. unused, expired antivenom may represent a significant, untapped resource to ameliorate this crisis. this study examines the efficacy of expired antivenom over time using in vitro, whole blood clotting, and platelet function statistics. representatives from three years for four ...201931229628
supracategorical fear information revealed by aversively conditioning multiple categories.fear-generalization is a critical function for survival, in which an organism extracts information from a specific instantiation of a threat (e.g., the western diamondback rattlesnake in my front yard on sunday) and learns to fear - and accordingly respond to - pertinent higher-order information (e.g., snakes live in my yard). previous work investigating fear-conditioning in humans has used functional magnetic resonance imaging (fmri) to demonstrate that activity patterns representing stimuli fr ...202033135598
toxicological profile of medically relevant crotalus species from mexico and their neutralization by a crotalus basiliscus/bothrops asper antivenom.specimens of the crotalus genus represent a potential snakebite problem in mexico, and despite the great number of species of crotalus present in this country, only a few of them are relevant from a medical point of view. crotalus envenomed patients can present a range of signs and symptoms, depending on the species involved, and their treatment is indistinctly with either of the anti-viperid antivenoms available in the mexican public health system. one of these antivenoms is produced by immuniz ...202032345455
toxin transcripts in crotalus atrox venom and in silico structures of toxins.the western diamondback rattlesnake (crotalus atrox) is a common and widespread north american pit viper species, and its venom possesses medical applications. in this research, we identified 14 of the most common transcripts encoding 11 major venom toxins including transcripts for a three-finger toxin (3ftx) from the crude venom of c. atrox. in silico three-dimensional (3d) structures of 9 venom toxins were predicted by using deduced toxin amino acid sequences and a computer programme-modeller. ...202032774833
repurposing cancer drugs batimastat and marimastat to inhibit the activity of a group i metalloprotease from the venom of the western diamondback rattlesnake, crotalus atrox.snakebite envenomation causes over 140,000 deaths every year, predominantly in developing countries. as a result, it is one of the most lethal neglected tropical diseases. it is associated with incredibly complex pathophysiology due to the vast number of unique toxins/proteins present in the venoms of diverse snake species found worldwide. here, we report the purification and functional characteristics of a group i (pi) metalloprotease (camp-2) from the venom of the western diamondback rattlesna ...202032397419
the origin and diversification of a novel protein family in venomous snakes.the genetic origins of novelty are a central interest of evolutionary biology. most new proteins evolve from preexisting proteins but the evolutionary path from ancestral gene to novel protein is challenging to trace, and therefore the requirements for and order of coding sequence changes, expression changes, or gene duplication are not clear. snake venoms are important novel traits that are comprised of toxins derived from several distinct protein families, but the genomic and evolutionary orig ...202032366667
comparison of thromboelastography versus conventional coagulation tests in simulated crotalus atrox envenomation using human blood.pit viper bites are a source of significant morbidity and mortality. pit viper bites can cause venom-induced consumptive coagulopathy (vicc), typically evaluated with laboratory-based conventional coagulation tests (ccts). however, ccts require a laboratory and average 1 h to conduct. thromboelastography (teg) provides real-time, point-of-care tests of coagulation that are fast and require no separate laboratory facilities, which could be advantageous in both hospital and austere settings. howev ...202031833475
crotalus atrox disintegrin reduces hemorrhagic transformation by attenuating matrix metalloproteinase-9 activity after middle cerebral artery occlusion in hyperglycemic male rats.hemorrhagic transformation after ischemic stroke is an independent predictor for poor outcome and is characterized by blood vessel rupture leading to brain edema. to date, no therapies for preventing hemorrhagic transformation exist. disintegrins from the venom of crotalus atrox have targets within the coagulation cascade, including receptors on platelets. we hypothesized that disintegrins from c. atrox venom can attenuate hemorrhagic transformation by preventing activation of matrix metalloprot ...202030242872
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