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1.
Behav Processes ; 168: 103960, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31518650

RESUMO

The tip of the tail in female Cerastes vipera, a small viperid snake, is black and conspicuous, whereas that of the male is not. We tested the hypothesis, albeit indirectly, that this sexual dimorphic chromatisation is related to caudal luring, a feeding mimicry hunting strategy. C. vipera can hunt nocturnally-active lizards only via sit-and-wait ambush and, consequently, we predicted that females would use caudal luring more often than males and that the proportion of nocturnal prey items in the diet of females would be higher than in males. Our hypothesis was supported as: 1) only females demonstrated caudal luring towards nocturnally-active lizards and more than 85% did so, whereas none of the males demonstrated such behavior; and 2) females consumed a significantly higher proportion (15/40 vs 4/27) of nocturnally-active lizards than did males. We concluded that sexual dichromatisation in C. vipera is associated with hunting strategy that results in different hunting behavior and different dietary intake between sexes. These novel findings: 1) provide a functional explanation for the black tail of female C. vipera; and 2) suggest different evolutionary driving forces between sexes and, consequently, different ecological impacts of male and female C. vipera on lizard populations.


Assuntos
Comportamento Alimentar/fisiologia , Comportamento Predatório/fisiologia , Caracteres Sexuais , Pigmentação da Pele , Meio Social , Viperidae/fisiologia , Animais , Feminino , Masculino , Comportamento Sexual/fisiologia
2.
PLoS One ; 14(4): e0214889, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30995262

RESUMO

Atractaspidines are poorly studied, fossorial snakes that are found throughout Africa and western Asia, including the Middle East. We employed concatenated gene-tree analyses and divergence dating approaches to investigate evolutionary relationships and biogeographic patterns of atractaspidines with a multi-locus data set consisting of three mitochondrial (16S, cyt b, and ND4) and two nuclear genes (c-mos and RAG1). We sampled 91 individuals from both atractaspidine genera (Atractaspis and Homoroselaps). Additionally, we used ancestral-state reconstructions to investigate fang and diet evolution within Atractaspidinae and its sister lineage (Aparallactinae). Our results indicated that current classification of atractaspidines underestimates diversity within the group. Diversification occurred predominantly between the Miocene and Pliocene. Ancestral-state reconstructions suggest that snake dentition in these taxa might be highly plastic within relatively short periods of time to facilitate adaptations to dynamic foraging and life-history strategies.


Assuntos
Viperidae/classificação , Viperidae/genética , Estruturas Animais/anatomia & histologia , Estruturas Animais/fisiologia , Animais , Citocromos b/genética , Evolução Molecular , Genes Mitocondriais , Genes RAG-1 , Genes mos , NADH Desidrogenase/genética , Filogenia , Comportamento Predatório , RNA Ribossômico 16S/genética , Fatores de Tempo , Viperidae/fisiologia
3.
Artigo em Inglês | MEDLINE | ID: mdl-30825636

RESUMO

Animal secretions are of great interest in terms of drug development due to their complex protein and peptide composition. Especially, in the field of therapeutic medications such as anti-cancer drugs snake venoms receive attention. In this study, we address two Viperidae species from various habitats with a particular focus on the cytotoxic potential along with the decomplexation of the venom proteome: the horned desert viper (Cerastes cerastes), native to desert regions of North Africa and the mangrove pit viper (Cryptelytrops purpureomaculatus), found in coastal forests of Southeast Asia. Initial cytotoxic screenings of the crude venoms revealed diverse activity, with the highest effect against SHSY5Y human glioblastoma carcinoma cells compared to other cancerous and non-cancerous cell lines. In-depth cytotoxicity studies of SHSY5Y cells with purified venom fractions revealed heterodimeric disintegrins from C. cerastes venom, which exerted a high cytotoxic activity with IC50 values from 0.11 to 0.58 µM and a disintegrin-like effect on SHSY5Y morphology was observed due to cell detachment. Furthermore, two polyproline BPP-related peptides, one PLA2 and a peptide-rich fraction were determined for C. purpureomaculatus with moderate IC50 values between 3 and 51 µM. Additionally, the decryption of the venom proteomes by snake venomic mass spectrometry and comparison of the same species from different habitats revealed slight differences in the composition.


Assuntos
Sobrevivência Celular/efeitos dos fármacos , Proteoma/metabolismo , Venenos de Víboras/química , Venenos de Víboras/toxicidade , Viperidae/fisiologia , Animais , Linhagem Celular , Ecossistema , Especificidade da Espécie
4.
Wilderness Environ Med ; 30(1): 66-78, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30711421

RESUMO

Thrombotic microangiopathy (TMA), which includes the spectrum of hemolytic uremic syndrome and thrombotic thrombocytopenic purpura, is an uncommon complication of hump-nosed pit viper envenomation. We describe 4 cases of TMA following hump-nosed pit viper (Hypnale spp) bites in Sri Lanka. The first case is a typical TMA that spontaneously resolved with supportive treatments. The second and third cases are related to hemolytic uremic syndrome complicated with acute kidney injury that required hemodialysis. The fourth case is thrombotic thrombocytopenic purpura associated with acute kidney injury that required hemodialysis and therapeutic plasma exchange. For each patient we describe the circumstances of the bite, clinical features, laboratory findings, and management.


Assuntos
Síndrome Hemolítico-Urêmica/etiologia , Púrpura Trombocitopênica Trombótica/etiologia , Mordeduras de Serpentes/terapia , Microangiopatias Trombóticas/etiologia , Venenos de Víboras/toxicidade , Viperidae/classificação , Idoso , Animais , Feminino , Síndrome Hemolítico-Urêmica/patologia , Síndrome Hemolítico-Urêmica/terapia , Humanos , Masculino , Pessoa de Meia-Idade , Púrpura Trombocitopênica Trombótica/patologia , Púrpura Trombocitopênica Trombótica/terapia , Sri Lanka , Microangiopatias Trombóticas/patologia , Viperidae/fisiologia
5.
Wilderness Environ Med ; 30(1): 56-58, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30385100

RESUMO

Bites by the European adder (Vipera berus) are a rare medical emergency in the UK with 20 to 50% of an estimated 50 to 200 cases per year necessitating treatment with antivenom. We present a case demonstrating both severe systemic and local effects necessitating out of hospital resuscitation, vasopressor support, and prolonged rehabilitation. Hemodynamic stability was restored promptly after administration of ViperaTAb antivenom, the first published case of its use in the UK.


Assuntos
Antivenenos/uso terapêutico , Mordeduras de Serpentes/tratamento farmacológico , Mordeduras de Serpentes/patologia , Venenos de Víboras/toxicidade , Viperidae/fisiologia , Animais , Feminino , Humanos , Pessoa de Meia-Idade , Reino Unido
6.
Zoology (Jena) ; 129: 25-34, 2018 08.
Artigo em Inglês | MEDLINE | ID: mdl-30170745

RESUMO

The non-venomous grass snake (Natrix helvetica) and the venomous adder (Vipera berus) are two native species that are often found in sympatry in Great Britain and Europe. They occupy partially overlapping ecological niches and prey on small vertebrates, but use different feeding strategies. Here, we investigated the morphologies of grass snakes and adders from Dorset (UK) using two-dimensional geometric morphometrics to assess the degree of sexual dimorphism in size and shape together with the relative impact of allometry and general body dimensions on head shape. Both species showed significant sexual dimorphism in head size, but not in head shape. We found a clear allometric pattern in N. helvetica, whereas allometry in V. berus was generally less pronounced. Body dimensions were strongly correlated with head shape in the grass snake, but not in the adder. The fact that V. berus is venomous appears to explain the lack of allometric patterns and the lack of an association between body dimensions and head shape. The high degree of size dimorphism identified in both species could originate from the advantages of reduced intraspecific competition that are conveyed by a partial differentiation in feeding morphology.


Assuntos
Colubridae/fisiologia , Viperidae/fisiologia , Animais , Tamanho Corporal , Feminino , Cabeça , Masculino , Caracteres Sexuais , Simpatria
7.
PLoS One ; 13(8): e0200672, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30125293

RESUMO

Desert communities world-wide are used as natural laboratories for the study of convergent evolution, yet inferences drawn from such studies are necessarily indirect. Here, we brought desert organisms together (rodents and vipers) from two deserts (Mojave and Negev). Both predators and prey in the Mojave have adaptations that give them competitive advantage compared to their middle-eastern counterparts. Heteromyid rodents of the Mojave, kangaroo rats and pocket mice, have fur-lined cheek pouches that allow them to carry larger loads of seeds under predation risk compared to gerbilline rodents of the Negev Deserts. Sidewinder rattlesnakes have heat-sensing pits, allowing them to hunt better on moonless nights when their Negev sidewinding counterpart, the Saharan horned vipers, are visually impaired. In behavioral-assays, we used giving-up density (GUD) to gauge how each species of rodent perceived risk posed by known and novel snakes. We repeated this for the same set of rodents at first encounter and again two months later following intensive "natural" exposure to both snake species. Pre-exposure, all rodents identified their evolutionarily familiar snake as a greater risk than the novel one. However, post-exposure all identified the heat-sensing sidewinder rattlesnake as a greater risk. The heteromyids were more likely to avoid encounters with, and discern the behavioral difference among, snakes than their gerbilline counterparts.


Assuntos
Evolução Biológica , Comportamento Predatório , Roedores/classificação , Roedores/psicologia , Viperidae/fisiologia , Animais , Masculino
8.
Sci Rep ; 8(1): 9818, 2018 06 29.
Artigo em Inglês | MEDLINE | ID: mdl-29959358

RESUMO

Medically relevant cases of snakebite in Europe are predominately caused by European vipers of the genus Vipera. Systemic envenoming by European vipers can cause severe pathology in humans and different clinical manifestations are associated with different members of this genus. The most representative vipers in Europe are V. aspis and V. berus and neurological symptoms have been reported in humans envenomed by the former but not by the latter species. In this study we determined the toxicological profile of V. aspis and V. berus venoms in vivo in mice and we tested the effectiveness of two antivenoms, commonly used as antidotes, in counteracting the specific activities of the two venoms. We found that V. aspis, but not V. berus, is neurotoxic and that this effect is due to the degeneration of peripheral nerve terminals at the NMJ and is not neutralized by the two tested antisera. Differently, V. berus causes a haemorrhagic effect, which is efficiently contrasted by the same antivenoms. These results indicate that the effectiveness of different antisera is strongly influenced by the variable composition of the venoms and reinforce the arguments supporting the use polyvalent antivenoms.


Assuntos
Antivenenos/farmacologia , Reações Cruzadas/imunologia , Junção Neuromuscular/patologia , Paralisia/patologia , Mordeduras de Serpentes/prevenção & controle , Venenos de Víboras/antagonistas & inibidores , Viperidae/classificação , Animais , Cerebelo/efeitos dos fármacos , Cerebelo/patologia , Reações Cruzadas/efeitos dos fármacos , Feminino , Soros Imunes/farmacologia , Camundongos , Neurônios Motores/efeitos dos fármacos , Neurônios Motores/patologia , Junção Neuromuscular/efeitos dos fármacos , Neurônios/efeitos dos fármacos , Neurônios/patologia , Paralisia/induzido quimicamente , Fosfolipases A2 , Ratos , Mordeduras de Serpentes/induzido quimicamente , Mordeduras de Serpentes/patologia , Venenos de Víboras/toxicidade , Viperidae/fisiologia
9.
Artigo em Inglês | MEDLINE | ID: mdl-29758383

RESUMO

Night adders (Causus species within the Viperidae family) are amphibian specialists and a common source of snakebite in Africa. Some species are unique in that they have the longest venom glands of any viper, extending approximately 10% of the body length. Despite their potential medical importance and evolutionary novelty, their venom has received almost no research attention. In this study, venoms from a short-glanded species (C. lichtensteinii) and from a long-glanded species (C. rhombeatus) were compared using a series of proteomic and bioactivity testing techniques to investigate and compare the toxin composition and functioning of the venoms of these two species. Both C. rhombeatus and C. lichtensteinii were similar in overall venom composition and inhibition of blood coagulation through non-clotting proteolytic cleavage of fibrinogen. While the 1D gel profiles were very similar to each other in the toxin types present, 2D gel analyses revealed isoformic differences within each toxin classes. This variation was congruent with differential efficacy of South African Institute for Medical Research snake polyvalent antivenom, with C. lichtensteinii unaffected at the dose tested while C. rhombeatus was moderately but significantly neutralized. Despite the variation within toxin classes, the similarity in overall venom biochemistry suggests that the selection pressure for the evolution of long glands served to increase venom yield in order to subjugate proportionally large anurans as a unique form of niche partitioning, and is not linked to significant changes in venom function. These results not only contribute to the body of venom evolution knowledge but also highlight the limited clinical management outcomes for Causus envenomations.


Assuntos
Evolução Biológica , Glândulas Exócrinas/crescimento & desenvolvimento , Modelos Biológicos , Comportamento Predatório , Venenos de Víboras/metabolismo , Viperidae/crescimento & desenvolvimento , Animais , Anticoagulantes/metabolismo , Anticoagulantes/farmacologia , Anticoagulantes/toxicidade , Coagulação Sanguínea/efeitos dos fármacos , Tamanho Corporal , Venenos Elapídicos/metabolismo , Venenos Elapídicos/farmacologia , Venenos Elapídicos/toxicidade , Elapidae , Eletroforese em Gel de Poliacrilamida , Glândulas Exócrinas/metabolismo , Fibrinogênio/metabolismo , Tamanho do Órgão , Filogenia , Proteólise/efeitos dos fármacos , Proteômica/métodos , Proteínas de Répteis/metabolismo , Especificidade da Espécie , Venenos de Víboras/farmacologia , Venenos de Víboras/toxicidade , Viperidae/fisiologia
10.
J Biochem Mol Toxicol ; 32(2)2018 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-29278277

RESUMO

Investigating new antimicrobial and antiparasitic components from Viperidae venoms represents an alternative therapeutic strategy. In this study, we report the characterization of a disintegrin isolated from Cerastes cerastes venom, exhibiting antiparasitic activity on Leishmania infantum promastigotes. Indeed, isolated disintegrin, referred to Disintegrin_Cc, induced 84.75% of parasiticidal activity and deep morphological alterations on the parasites. SDS-PAGE analysis indicated that this disintegrin was homogenous. This dimeric disintegrin of 14,193.97 Da contains an RGD domain and four intramolecular disulfide bridges. It presents a high percentage of identity with other related snake disintegrins. Predicted 3D structure indicated that this peptide shares partial homology with well-known active antimicrobial peptides. Disintegrin_Cc inhibited 80% of arachidonic acid-induced platelet aggregation. The obtained results suggest that the isolated molecule plays a dual role as a disintegrin and as an anti-leishmanial compound. This component could be useful as a drug in the treatment of leishmaniasis.


Assuntos
Antiparasitários/farmacologia , Desintegrinas/farmacologia , Leishmania infantum/efeitos dos fármacos , Proteínas de Répteis/farmacologia , Venenos de Víboras/química , Viperidae/fisiologia , Sequência de Aminoácidos , Animais , Antiparasitários/química , Antiparasitários/isolamento & purificação , Sobrevivência Celular , Biologia Computacional , Sequência Conservada , Dimerização , Desintegrinas/química , Desintegrinas/genética , Desintegrinas/isolamento & purificação , Sistemas Especialistas , Ontologia Genética , Leishmania infantum/crescimento & desenvolvimento , Peso Molecular , Filogenia , Agregação Plaquetária/efeitos dos fármacos , Inibidores da Agregação de Plaquetas/química , Inibidores da Agregação de Plaquetas/isolamento & purificação , Inibidores da Agregação de Plaquetas/farmacologia , Conformação Proteica , Domínios e Motivos de Interação entre Proteínas , Proteínas de Répteis/química , Proteínas de Répteis/genética , Proteínas de Répteis/isolamento & purificação , Alinhamento de Sequência , Homologia de Sequência de Aminoácidos , Venenos de Víboras/enzimologia
11.
Proc Biol Sci ; 284(1869)2017 Dec 20.
Artigo em Inglês | MEDLINE | ID: mdl-29263281

RESUMO

An increase in ecological opportunities, either through changes in the environment or acquisition of new traits, is frequently associated with an increase in species and morphological diversification. However, it is possible that certain ecological settings might prevent lineages from diversifying. Arboreality evolved multiple times in vipers, making them ideal organisms for exploring how potentially new ecological opportunities affect their morphology and speciation regimes. Arboreal snakes are frequently suggested to have a very specialized morphology, and being too large, too small, too heavy, or having short tails might be challenging for them. Using trait-evolution models, we show that arboreal vipers are evolving towards intermediate body sizes, with longer tails and more slender bodies than terrestrial vipers. Arboreality strongly constrains body size and circumference evolution in vipers, while terrestrial lineages are evolving towards a broader range of morphological variants. Trait-dependent diversification models, however, suggest similar speciation rates between microhabitats. Thus, we show that arboreality might constrain morphological evolution but not necessarily affect the rates at which lineages generate new species.


Assuntos
Evolução Biológica , Tamanho Corporal , Ecossistema , Viperidae/anatomia & histologia , Viperidae/fisiologia , Animais , Locomoção , Árvores
12.
Physiol Biochem Zool ; 90(6): 663-672, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-29068263

RESUMO

Water constraints can mediate evolutionary conflict either among individuals (e.g., parent-offspring conflict, sexual conflict) or within an individual (e.g., cost of reproduction). During pregnancy, water is of particular importance because the female provides all water needed for embryonic development and experiences important maternal shifts in behavior and physiology that, together, can compromise female water balance if water availability is limited. We examined the effect of pregnancy on evaporative water loss and microhabitat selection in a viviparous snake, the aspic viper. We found that both physiological (increased metabolism and body temperature) and morphological (body distension) changes contribute to an increased evaporative water loss in pregnant females. We also found that pregnant females in the wild select warmer and moister basking locations than nonreproductive females, likely to mitigate the conflict between thermal needs and water loss. Water resources likely induce significant reproductive constraints across diverse taxa and thus warrant further consideration in ecological research. From an evolutionary perspective, water constraints during reproduction may contribute to shaping reproductive effort.


Assuntos
Viperidae/fisiologia , Viviparidade não Mamífera/fisiologia , Perda Insensível de Água/fisiologia , Animais , Feminino
13.
Acta Trop ; 173: 116-124, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28606819

RESUMO

Envenomation caused by Cerastes cerastes snake venom is characterized by a local and a systemic tissue damage due to myonecrosis, hemorrhage, edema and acute muscle damage. The present study aimed to evaluate the relationship between the pro/anti-oxidants status and the cytotoxicity of C. cerastes snake venom. The in vivo cytotoxicity analysis was undertaken by the injection of C. cerastes venom (48µg/20g body weight) by i.p. route, mice were then sacrificed at 3, 24 and 48h post injection, organs were collected for further analysis. In vitro cytotoxicity analysis was investigated on cultured PBMC, hepatocytes and isolated liver. The obtained results showed a significant cell infiltration characterized by a significant increase of myeloperoxidase (MPO) and eosinoperoxidase (EPO) activities. These results showed also a potent oxidative activity of C. cerastes venom characterized by increased levels of residual nitrites and lipid peroxidation associated with a significant decrease of glutathione and catalase activity in sera and tissues (heart, lungs, liver and kidneys). The in vitro cytotoxicity of C. cerastes venom on PBMC seems to be dose-dependent (IC50 of 21µg/ml/106 cells) and correlated with an imbalanced redox status at high doses of venom. However, in the case of cultured hepatocytes, the LDH release and oxidative stress were observed only at high doses of the venom. The obtained results of in vivo study were confirmed by the culture of isolated liver. Therefore, these results suggest that the venom induces a direct cytotoxic effect which alters the membrane integrity causing a leakage of the cellular contents. This cytotoxic effect can lead indirectly to inflammatory response and oxidative stress. These data suggest that an early anti-inflammatory and antioxidant treatment could be useful in the management of envenomed victims.


Assuntos
Leucócitos Mononucleares/efeitos dos fármacos , Venenos de Víboras/toxicidade , Viperidae/fisiologia , Animais , Edema , Coração/efeitos dos fármacos , Hepatócitos/efeitos dos fármacos , Fígado/efeitos dos fármacos , Masculino , Camundongos , Oxirredução , Estresse Oxidativo
14.
Acta Vet Scand ; 59(1): 28, 2017 May 03.
Artigo em Inglês | MEDLINE | ID: mdl-28468664

RESUMO

BACKGROUND: Vipera berus has a worldwide distribution and causes high morbidity in dogs annually. A complication to envenomation may be cardiac arrhythmias. The purpose of this study was to investigate the prevalence, types, and timing of arrhythmias, using 24-h ambulatory electrocardiography (24-AECG), in dogs bitten by V. berus in the first 24-32 h after envenomation. In addition, this study aimed to investigate if there were differences in selected clinical and hematological- and biochemical variables (including cardiac troponin I) at admission between V. berus-envenomed dogs with and without detected pathologic arrhythmias. Seventeen prospectively recruited client-owned dogs acutely envenomed by V. berus, were therefore examined clinically and echocardiographically, sampled for blood, hospitalized, and monitored by 24-AECG. RESULTS: Clinically significant pathologic arrhythmias in this study were of ventricular origin, such as frequent single ventricular premature contractions (VPCs) and couplets of VPCs, episodes of ventricular tachycardia and idioventricular rhythm, and "R-on-T phenomenon". Variations of these arrhythmias were detected by 24-AECG in eight (47%) of included dogs. No arrhythmias were detected by cardiac auscultation. Twenty-four hours following envenomation, four out of eight dogs experienced decreases (all P < 0.039), and three out of eight dogs experienced increases (all P < 0.034), in arrhythmic episodes. All four dogs bitten on a limb developed pathologic arrhythmias. Otherwise, no significant differences in clinical, hematological or biochemical variables were seen between dogs with pathologic arrhythmias and those without. CONCLUSION: Forty-seven percent of dogs bitten by V. berus included in this study experienced pathologic arrhythmias of abnormal ventricular depolarization. During the first 24-32 h from the snakebite, some dogs experienced a decrease in arrhythmic episodes and others an increase in arrhythmic episodes. These findings indicate a potential value of repeated or prolonged electrocardiography monitoring of envenomed dogs for identification of which dogs that might benefit the most from prolonged hospitalization for optimal monitoring and treatment of cardiac abnormalities. In the present study, dogs that developed arrhythmias could not be differentiated from dogs that did not based on clinical findings or hematological or biochemical variables obtained at admission.


Assuntos
Arritmias Cardíacas/veterinária , Doenças do Cão/etiologia , Eletrocardiografia Ambulatorial/veterinária , Mordeduras de Serpentes/veterinária , Venenos de Víboras/toxicidade , Viperidae/fisiologia , Animais , Arritmias Cardíacas/etiologia , Arritmias Cardíacas/patologia , Doenças do Cão/patologia , Cães , Feminino , Masculino
15.
Acta Trop ; 171: 226-232, 2017 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-28427959

RESUMO

It is well known that snake venoms such as Viperidae caused severe local effects such as hemorrhage, myonecrosis and dermonecrosis which can lead to permanent tissue loss or the disability. The aim of this study is to evaluate the skin regeneration using heparin and l-arginine as well as the dermonecrotic effects induced by Vipera lebetina venom (VLV). To better understand the toxic effects induced by VLV and to prevent or treat these effects, we evaluate the local effects and the skin regeneration with or without drugs. The evaluation of NO as a marker of angiogenesis was also undertaken to understand its involvement in tissue wound healing and skin regeneration after envenomation. Obtained results showed that this venom is able to induce severe necrosis characterized by hemorrhage, hair follicles' destruction, glandular structure and increased of the thickness (acanthosis) in the epidermo-dermic junction. Inflammatory cells were also observed in the dermis. Pretreatment with heparin or L arginine seemed to decrease the induced dermonecrotic after one and two weeks improving the skin regeneration. The high level of NO could be involved in this regeneration, since it participates in the skin homeostatic functions' regulation and the maintenance of the skin protective barrier integrity against microorgansims. Nitric oxide plays also a key role in wound healing; it acts as a potent mitogenic stimulus to keratinocytes during skin repair and enhances the hair follicles and sebaceous gland structure that appeared after two weeks of treatment. Thus, these drugs could be used in therapeutic approach for dermonecrotic skin repair.


Assuntos
Arginina/farmacologia , Heparina/farmacologia , Necrose/induzido quimicamente , Dermatopatias/induzido quimicamente , Venenos de Víboras/toxicidade , Viperidae/fisiologia , Animais , Necrose/tratamento farmacológico , Dermatopatias/tratamento farmacológico , Dermatopatias/patologia
16.
J Exp Biol ; 220(Pt 10): 1792-1796, 2017 05 15.
Artigo em Inglês | MEDLINE | ID: mdl-28292781

RESUMO

The physiological mechanisms underlying the 'cost of reproduction' remain under debate, though oxidative stress has emerged as a potential candidate. The 'oxidative cost of reproduction' has received considerable attention with regards to food and antioxidant availability; however, the limitation of water availability has thus far been neglected. In this study, we experimentally examined the combined effect of pregnancy and water deprivation on oxidative status in a viviparous snake (Vipera aspis), a species naturally exposed to periods of water and food deprivation. We predicted a cumulative effect of pregnancy and dehydration on oxidative stress levels. Our results support the occurrence of an oxidative cost of reproduction as we found higher oxidative damage levels in pregnant females than in non-reproductive individuals, despite an up-regulation of antioxidant defences. Surprisingly, water deprivation was associated with an up-regulation of antioxidant defences, and did not increase oxidative damage, either alone or in combination with reproduction.


Assuntos
Estresse Oxidativo , Viperidae/fisiologia , Viviparidade não Mamífera/fisiologia , Animais , Antioxidantes/metabolismo , Desidratação , Eritrócitos/química , Feminino , Reprodução/fisiologia , Regulação para Cima , Água
17.
Am J Trop Med Hyg ; 96(4): 885-886, 2017 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-28167587

RESUMO

AbstractSnake bite is an important health hazard in tropics. Snake envenomation in pregnancy may cause fetal death and maternal mortality or morbidity. However, little is known about the toxic effects and optimal management during pregnancy after snake envenomation because of the rarity of cases. Herein, we report a case of a pregnant woman who was successfully treated for snake bite-induced acute kidney injury during the third trimester. She was treated with equine-derived polyvalent anti-snake venom without development of any adverse effects, hemodialysis, and supportive therapy. She fully recovered and subsequently gave birth to a healthy child.


Assuntos
Lesão Renal Aguda/induzido quimicamente , Mordeduras de Serpentes/complicações , Adulto , Animais , Antivenenos/uso terapêutico , Feminino , Humanos , Gravidez , Complicações na Gravidez , Resultado da Gravidez , Diálise Renal , Mordeduras de Serpentes/patologia , Mordeduras de Serpentes/terapia , Viperidae/fisiologia
18.
PLoS One ; 12(2): e0172011, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28196149

RESUMO

Elucidating how life history traits vary geographically is important to understanding variation in population dynamics. Because many aspects of ectotherm life history are climate-dependent, geographic variation in climate is expected to have a large impact on population dynamics through effects on annual survival, body size, growth rate, age at first reproduction, size-fecundity relationship, and reproductive frequency. The Eastern Massasauga (Sistrurus catenatus) is a small, imperiled North American rattlesnake with a distribution centered on the Great Lakes region, where lake effects strongly influence local conditions. To address Eastern Massasauga life history data gaps, we compiled data from 47 study sites representing 38 counties across the range. We used multimodel inference and general linear models with geographic coordinates and annual climate normals as explanatory variables to clarify patterns of variation in life history traits. We found strong evidence for geographic variation in six of nine life history variables. Adult female snout-vent length and neonate mass increased with increasing mean annual precipitation. Litter size decreased with increasing mean temperature, and the size-fecundity relationship and growth prior to first hibernation both increased with increasing latitude. The proportion of gravid females also increased with increasing latitude, but this relationship may be the result of geographically varying detection bias. Our results provide insights into ectotherm life history variation and fill critical data gaps, which will inform Eastern Massasauga conservation efforts by improving biological realism for models of population viability and climate change.


Assuntos
Mudança Climática , Variação Genética , Modelos Biológicos , Viperidae/fisiologia , Animais , Feminino , Great Lakes Region , Masculino
19.
Behav Processes ; 135: 40-44, 2017 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-27899311

RESUMO

Sit-and-wait ambushing and active hunting are two strategies used by predators to capture prey. In snakes, hunting strategy is conserved phylogenetically; most species employ only one strategy. Active hunters encounter and capture more prey but invest more energy in hunting and have higher risks of being predated. This trade-off is important to small predators. The small Cerastes vipera employs both modes of hunting, which is unlike most viperids which use only sit-and wait ambushing. This species hibernates in October and emerges in April. Energy intake should be high prior to hibernation to overcome the non-feeding hibernation period and for reproduction on their emergence. We predicted that more individuals would hunt actively towards hibernation and an abiotic factor would trigger this response. Furthermore, since more energy is required for active hunting, we predicted that snakes in good body condition would use active hunting to a greater extent than snakes in poor body condition. To test our predictions, we tracked free-living snakes year round and determined their hunting strategy, estimated their body condition index (BCI), and calculated circannual parameters of day length as environmental cues known to affect animal behaviour. Two novel findings emerged in this study, namely, hunting strategy was affected significantly by 1) the circannual change in day length and 2) by BCI. The proportion of active hunters increased from 5% in April to over 30% in October and BCI of active foragers was higher than that of sit-and-wait foragers and, therefore, our predictions were supported. The entrainment between the proportion of active hunting and the abiotic factor is indicative of an adaptive function for choosing a hunting strategy. A trend was evident among life stages. When all life stages were present (September-October), the proportion of active foragers increased with age: 0.0% among neonates, 18.2% among juveniles and 31.4% among adults. We concluded that vulnerable small neonates used sit-and-wait ambush not only as a hunting strategy but also as a hiding technique.


Assuntos
Periodicidade , Comportamento Predatório/fisiologia , Viperidae/fisiologia , Fatores Etários , Animais , Israel
20.
Zootaxa ; 4093(1): 41-63, 2016 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-27394480

RESUMO

A new species of viperine viperid snake is described, Bitis harenna sp. nov. The new species is a member of the subgenus Macrocerastes based on it having three scales separating the nasal and rostral shields, and on the combination of 'divisions' of dorsal scale rows on the upper flanks and 'fusions' of rows on the lower flanks. Bitis harenna sp. nov. is distinguished from other members of the subgenus by its unique colour pattern, posterior parietal flange on the lateral wall of the braincase, and possibly by differences in scalation and head proportions. Only a single museum specimen is known, a female collected from 'Dodola' in Ethiopia probably in the late 1960s and previously identified as a possibly unusually coloured and patterned B. parviocula. A live, presumably male, specimen very closely resembling the holotype of Bitis harenna sp. nov. was photographed on the Harenna escarpment of the Bale Mountains National Park, Ethiopia in 2013, providing secure occurrence data and evidence that the holotype is not a uniquely aberrant specimen. A revised key to the species of Bitis in Ethiopia is presented. Aspects of body scalation are compared among species of the subgenus Macrocerastes and between species of Macrocerastes and Bitis, and several systematic characters are highlighted and clarified.


Assuntos
Viperidae/anatomia & histologia , Viperidae/classificação , Distribuição Animal , Animais , Etiópia , Feminino , Masculino , Especificidade da Espécie , Viperidae/fisiologia
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