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1.
Toxins (Basel) ; 15(1)2023 Jan 13.
Artigo em Inglês | MEDLINE | ID: mdl-36668892

RESUMO

Snake venoms are complex mixtures of toxins that differ on interspecific (between species) and intraspecific (within species) levels. Whether venom variation within a group of closely related species is explained by the presence, absence and/or relative abundances of venom toxins remains largely unknown. Taipans (Oxyuranus spp.) and brown snakes (Pseudonaja spp.) represent medically relevant species of snakes across the Australasian region and provide an excellent model clade for studying interspecific and intraspecific venom variation. Using liquid chromatography with ultraviolet and mass spectrometry detection, we analyzed a total of 31 venoms covering all species of this monophyletic clade, including widespread localities. Our results reveal major interspecific and intraspecific venom variation in Oxyuranus and Pseudonaja species, partially corresponding with their geographical regions and phylogenetic relationships. This extensive venom variability is generated by a combination of the absence/presence and differential abundance of venom toxins. Our study highlights that venom systems can be highly dynamical on the interspecific and intraspecific levels and underscores that the rapid toxin evolvability potentially causes major impacts on neglected tropical snakebites.


Assuntos
Mordeduras de Serpentes , Toxinas Biológicas , Animais , Venenos Elapídicos/genética , Filogenia , Elapidae/genética , Venenos de Serpentes , Serpentes , Antivenenos
2.
Parasit Vectors ; 16(1): 6, 2023 Jan 06.
Artigo em Inglês | MEDLINE | ID: mdl-36609309

RESUMO

BACKGROUND: Ophionyssus natricis is the main species of mite that infests captive reptiles. High infestations may result in the host experiencing general discomfort and deleterious effects, even death. Moreover, O. natricis is an important vector of reptile vector-borne diseases and is considered to be the putative vector of the Reptarenavirus, the causal agent of the inclusion body disease. Despite the cosmopolitan distribution of O. natricis in captive reptiles, treatment options are limited. The aim of the present study was to assess the efficacy of afoxolaner (NexGard®; Boehringer Ingelheim, Ingelheim, Germany) in heavily infested, privately owned snakes, evaluate the prevalence of mites and drug availability in the plasma of treated snakes (pharmacokinetics) and perform a clinical examination of animals. METHODS: The study was conducted in two snake breeding facilities, where many snakes were infested with mites. Each animal was clinically examined and weighed, and mite infestations were assessed on the animals and in their enclosures (environment). Animals were treated with a dose of 2.5 mg afoxolaner per kilogram body weight (2.5 mg/kg) administered orally. All animals were examined pre-treatment (T0) and at various time points post-treatment (T1, 6 h; T2, 24 h; T3, 14 days; T4, 28 days). The collected mites were morphologically identified at the species level and the species identity also confirmed molecularly. RESULTS: Overall, 81 snakes from the two participating facilities (i.e. 70 from site 1 and 11 from site 2) were screened, and 31 (38.3%) snakes were found to have at least one mite. All mites were identified morphologically and molecularly as O. natricis. Lampropeltis was the genus of snakes with highest number of infested individuals. Mites were found to be alive on snakes at T1, but at T2 only dead mites were observed, and at T3 and T4 mites were no longer present on the animals or in their environment. No side effects were observed in the treated snakes. CONCLUSIONS: A single oral administration of afoxolaner at 2.5 mg/kg was a safe treatment for snakes and 100% effective for the eradication of natural O. natricis infestation without the need to treat the environment of the snake.


Assuntos
Doenças do Cão , Infestações por Ácaros , Ácaros , Animais , Cães , Infestações por Ácaros/tratamento farmacológico , Infestações por Ácaros/prevenção & controle , Infestações por Ácaros/veterinária , Serpentes , Isoxazóis , Doenças do Cão/tratamento farmacológico
3.
J Helminthol ; 97: e3, 2023 Jan 13.
Artigo em Inglês | MEDLINE | ID: mdl-36637249

RESUMO

Reptiles, as well as other vertebrate groups, harbour a significant diversity of parasitic organisms, from nematodes and other helminths to viruses and bacteria. The Northeast is one of the richest regions in Brazil in terms of the reptile diversity, number of species and endemism. Parasites are diverse organisms and knowledge about the parasitic fauna of vertebrates is an important factor in understanding the ecological relationships between hosts and the environment. Studies on the parasitic fauna of reptiles in South America have increased in the past few years. The present review is a compilation of 122 studies published from 1924 to 2021. We present information on 101 species of reptiles from five groups (amphisbaenians, crocodile, testudines, snakes and lizards) and 183 parasitic taxa belonging to four phyla: Nematoda; Arthropoda; Platyhelminthes; and Acanthocephala. Nematodes were the most frequently recorded species. Lizards and snakes had more records of parasitism and higher levels of parasite richness and diversity. Ceará was the state with most studies and recorded cases of parasite-host association. The Caatinga and Atlantic Forest were the most investigated environments. The objective of this review was to contribute knowledge on the parasitic biodiversity in reptiles from Northeast Brazil, which may help identify gaps in our knowledge and guide future studies.


Assuntos
Lagartos , Nematoides , Parasitos , Animais , Brasil , Lista de Checagem , Lagartos/parasitologia , Serpentes/parasitologia
4.
Mol Phylogenet Evol ; 178: 107635, 2023 01.
Artigo em Inglês | MEDLINE | ID: mdl-36208694

RESUMO

Most of the unique and diverse vertebrate fauna that inhabits Madagascar derives from in situ diversification from colonisers that reached this continental island through overseas dispersal. The endemic Malagasy Scincinae lizards are amongst the most species-rich squamate groups on the island. They colonised all bioclimatic zones and display many ecomorphological adaptations to a fossorial (burrowing) lifestyle. Here we propose a new phylogenetic hypothesis for their diversification based on the largest taxon sampling so far compiled for this group. We estimated divergence times and investigated several aspects of their diversification (diversification rate, body size and fossorial lifestyle evolution, and biogeography). We found that diversification rate was constant throughout most of the evolutionary history of the group, but decreased over the last 6-4 million years and independently from body size and fossorial lifestyle evolution. Fossoriality has evolved from fully quadrupedal ancestors at least five times independently, which demonstrates that even complex morphological syndromes - in this case involving traits such as limb regression, body elongation, modification of cephalic scalation, depigmentation, and eyes and ear-opening regression - can evolve repeatedly and independently given enough time and eco-evolutionary advantages. Initial diversification of the group likely occurred in forests, and the divergence of sand-swimmer genera around 20 Ma appears linked to a period of aridification. Our results show that the large phenotypic variability of Malagasy Scincinae has not influenced diversification rate and that their rich species diversity results from a constant accumulation of lineages through time. By compiling large geographic and trait-related datasets together with the computation of a new time tree for the group, our study contributes important insights on the diversification of Malagasy vertebrates.


Assuntos
Lagartos , Animais , Filogenia , Serpentes , Tamanho Corporal , Madagáscar
5.
Mol Phylogenet Evol ; 178: 107651, 2023 01.
Artigo em Inglês | MEDLINE | ID: mdl-36306995

RESUMO

Uropeltidae is a clade of small fossorial snakes (ca. 64 extant species) endemic to peninsular India and Sri Lanka. Uropeltid taxonomy has been confusing, and the status of some species has not been revised for over a century. Attempts to revise uropeltid systematics and undertake evolutionary studies have been hampered by incompletely sampled and incompletely resolved phylogenies. To address this issue, we take advantage of historical museum collections, including type specimens, and apply genome-wide shotgun (GWS) sequencing, along with recent field sampling (using Sanger sequencing) to establish a near-complete multilocus species-level phylogeny (ca. 87% complete at species level). This results in a phylogeny that supports the monophyly of all genera (if Brachyophidium is considered a junior synonym of Teretrurus), and provides a firm platform for future taxonomic revision. Sri Lankan uropeltids are probably monophyletic, indicating a single colonisation event of this island from Indian ancestors. However, the position of Rhinophis goweri (endemic to Eastern Ghats, southern India) is unclear and warrants further investigation, and evidence that it may nest within the Sri Lankan radiation indicates a possible recolonisation event. DNA sequence data and morphology suggest that currently recognised uropeltid species diversity is substantially underestimated. Our study highlights the benefits of integrating museum collections in molecular genetic analyses and their role in understanding the systematics and evolutionary history of understudied organismal groups.


Assuntos
Museus , Serpentes , Animais , Filogenia , Serpentes/genética , Sequência de Bases , Sri Lanka
6.
Toxicon ; 222: 107003, 2023 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-36535530

RESUMO

A comprehensive assessment of the literature on strategies for the detection and removing endotoxin from biotechnological preparations was conducted. This study highlighted the brief history of endotoxin. After that, a review of endotoxin's chemical and physical features, as well as its pathophysiological consequences when the body is exposed to LPS excessively or systemically, is presented. The procedures for determining endotoxin and the interaction of endotoxin with proteins are also discussed, considering both known approaches and cutting-edge technology in this sector. This review presented the endotoxin detection and removal approaches from antisera with an economical approach using several processes documented in the literature (e.g., adsorption, ultrafiltration, and chromatography). Different methods with relatively high protein recoveries are mentioned. This review concludes that heat activation at 70 °C-80 °C for 10 min and rehydration of the LAL reagent with endotoxin-specific buffer solution is the best technique to control the enhancement problem when testing polyvalent snake venom antiserum samples by the LAL method. The most efficient method for eliminating endotoxins has proven to be affinity resin-based chromatography.


Assuntos
Antivenenos , Endotoxinas , Animais , Endotoxinas/análise , Antivenenos/análise , Proteínas , Adsorção , Serpentes
7.
Toxicon ; 223: 106995, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36566992

RESUMO

Snakebites can be caused by harmless or venomous snakes and, according to their severity and frequency, can be considered events of medical importance. In health facilities in remote areas, nurses work in the first line of care of patients that are victims of these envenomations. The aim was to discover the perception of nurses regarding the management of snakebites, its limitations and possibilities, with a view to professional empowerment in the context of primary health care. This is exploratory and descriptive research, with a qualitative approach, developed at FMT-HVD in Manaus, Amazonas state, Brazil, in the year 2021. The participants were nurses who work in basic health units in the municipalities of Careiro da Várzea, Ipixuna and Boa Vista do Ramos in the state of Amazonas. For data collection, the focus group strategy was adopted. Thematic content analysis was employed, which was carried out in the stages of pre-analysis; exploration or coding of the material; treatment of the results, inference and interpretation. After processing the data obtained, four topics emerged from the coding: Topic 1 - limitations in the primary care. Topic 2 - the need for infrastructure and personnel. Topic 3 - the need for continuing education. Topic 4 - the perception of training regarding the management of snakebite envenomations. The results showed a lack of antivenom in the healthcare units where nurses work. Another aspect highlighted by the nurses is the absence of a doctor in situ to perform the primary care or out of hours care in the units. The nurses' perceptions regarding the management of snakebite envenomations revealed the existence of failures in relation to the subject, such as the lack of antivenom, poor infrastructure in the units and the lack of a doctor, which must be solved, since the nurses are the most active professionals in primary health care, in addition to the high incidence of snakebite envenomations in the Brazilian Amazon.


Assuntos
Enfermeiras e Enfermeiros , Mordeduras de Serpentes , Animais , Humanos , Mordeduras de Serpentes/epidemiologia , Antivenenos/uso terapêutico , Serpentes , Incidência
8.
J Dermatol ; 49(1): 124-132, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34611926

RESUMO

Mamushi bites cause swelling and pain that extend from the bitten site. The coagulopathic, anti-coagulopathic, and vasculopathic actions of mamushi venom result in various laboratory abnormalities, occasionally with muscular, renal, and other organ damage. We investigated the serum biomarkers that were associated with the pathogenesis of mamushi bites, focusing on markers related to tissue-damage and neutrophil activation. Twenty patients (one case of grade 2, 13 cases of grade 3, and six cases of grade 4 of severity) seen by us in one summer season were enrolled. Peripheral blood samples were taken from the patients on day 0, day 2, and day 7 after mamushi bites. In addition to routine blood examination, serum samples were subjected to enzyme-linked immunosorbent assay for citrullinated histone H3 (CitH3), interleukin (IL)-8, IL-17A, IL-22, vascular endothelial growth factor (VEGF), high mobility group box protein 1 (HMGB1), tumor necrosis factor (TNF)-α, and IL-33. Creatinine kinase (CK) values significantly correlated with prothrombin time (PT) levels, suggesting that muscular damage is associated with exaggerated coagulation and fibrinolysis. In the vast majority of patients, HMGB1, TNF-α, and IL-33 were under detection levels. Neutrophil counts did not correlate with PT or CK, indicating that the coagulation disorder and muscular damage were virtually independent of the neutrophil activation. The neutrophil number significantly correlated with CitH3, a representative marker of neutrophil extracellular traps. Moreover, there were significant correlations between neutrophil number, CitH3, IL-8, IL-22, and VEGF. Our study suggests that there are two major cascades in mamushi bites. One is an already characterized venom effect on coagulation, vessels, and muscles. In the other novel cascade, we propose that neutrophil activation with IL-8 leads to the production of IL-22 and VEGF. This sequential event may contribute to both vascular damage and repair.


Assuntos
Armadilhas Extracelulares , Fator A de Crescimento do Endotélio Vascular , Animais , Humanos , Interleucina-8 , Interleucinas , Serpentes
9.
S Afr Med J ; 112(12): 892-896, 2022 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-36472321

RESUMO

Wound infections following cytotoxic snakebites are common. Bites from Naja nigricincta nigricincta (an African spitting cobra) usually present as severe dermonecrosis spreading within the subdermal fascia layer. Primary infections can follow inoculation of the snake's oral flora during the bite, worsening the dermonecrosis into infective necrotising fasciitis. We report the case of a 2½-year-old boy who presented with infective (Proteus vulgaris) necrotising fasciitis after an N. n. nigricincta bite, resulting in multiple-organ failure and death. A P. vulgaris with the same antibiotic profile was cultured from the mouth of the snake.


Assuntos
Fasciite Necrosante , Mordeduras de Serpentes , Animais , Humanos , Naja , Venenos Elapídicos , Fasciite Necrosante/complicações , Equidae , África do Sul , Mordeduras de Serpentes/complicações , Serpentes , Antivenenos
10.
J Evol Biol ; 35(12): 1791-1796, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-36455931

RESUMO

The reconstruction of the evolutionary history of sex determination in squamate reptiles (lizards and snakes) is complicated by missing data in many lineages, erroneous reports, and often questionable inferences on state homology. Therefore, despite the large effort, the reconstruction of the ancestral sex determination in squamate reptiles is still controversial. With the hope to shed light on this problem, we aspired to identify the sex chromosome gene content in Dibamus deharvengi, the representative of the family Dibamidae, the putative sister clade to all other squamates. Our analyses revealed XX/XY sex-determination system in D. deharvengi: the X chromosome contains genes with homologues scattered across chicken chromosomes 8, 12, 13, 18, 30, and 33, and the Y chromosome seems to largely degenerate. To the best of our knowledge, this combination has never been reported to form sex chromosomes in any amniote lineage. It suggests that the sex chromosomes can represent an apomorphy of a clade including D. deharvengi. Our findings cover an important gap in the knowledge of sex determination in reptiles and further support multiple independent origins of sex chromosomes in this group.


Assuntos
Lagartos , Animais , Lagartos/genética , Cromossomos Sexuais/genética , Cromossomo Y , Cromossomo X , Serpentes/genética
11.
Proc Biol Sci ; 289(1989): 20221734, 2022 Dec 21.
Artigo em Inglês | MEDLINE | ID: mdl-36541171

RESUMO

The pendent nests of some weaverbird and icterid species are among the most complex structures built by any animal, but why they have evolved remains to be explained. The precarious attachments and extended entrance tunnels characteristic of these nests are widely speculated to act as structural defences against invasion by nest predators, particularly tree-climbing snakes, but this hypothesis has yet to be systematically tested. We use phylogenetic comparative methods to investigate the relationship between nest structure and developmental period length, a proxy for offspring mortality, in weaverbirds (Ploceidae) and icterids (Icteridae), two bird families in which highly elaborate pendent nests have independently evolved. We find that more elaborate nests, particularly those with entrance tunnels, are associated with longer developmental periods in both families. This finding is robust to potentially confounding effects of body mass, phylogenetic relationships, nest location and latitude. Our results are consistent with the hypothesis that elaborate nest structures in birds can function as structural defences, resulting in lower offspring mortality and slower development. More generally, our findings suggest that constructing complex, protective structures may buffer against environmental hazards, reducing extrinsic mortality and contributing to the evolution of slower life histories in diverse animal lineages, even humans.


Assuntos
Comportamento de Nidação , Passeriformes , Animais , Humanos , Filogenia , Serpentes
12.
Toxins (Basel) ; 14(12)2022 12 01.
Artigo em Inglês | MEDLINE | ID: mdl-36548740

RESUMO

The evolution of venom and the selection pressures that act on toxins have been increasingly researched within toxinology in the last two decades, in part due to the exceptionally high rates of diversifying selection observed in animal toxins. In 2015, Sungar and Moran proposed the 'two-speed' model of toxin evolution linking evolutionary age of a group to the rates of selection acting on toxins but due to a lack of data, mammals were not included as less than 30 species of venomous mammal have been recorded, represented by elusive species which produce small amounts of venom. Due to advances in genomics and transcriptomics, the availability of toxin sequences from venomous mammals has been increasing. Using branch- and site-specific selection models, we present the rates of both episodic and pervasive selection acting upon venomous mammal toxins as a group for the first time. We identified seven toxin groups present within venomous mammals, representing Chiroptera, Eulipotyphla and Monotremata: KLK1, Plasminogen Activator, Desmallipins, PACAP, CRiSP, Kunitz Domain One and Kunitz Domain Two. All but one group (KLK1) was identified by our results to be evolving under both episodic and pervasive diversifying selection with four toxin groups having sites that were implicated in the fitness of the animal by TreeSAAP (Selection on Amino Acid Properties). Our results suggest that venomous mammal ecology, behaviour or genomic evolution are the main drivers of selection, although evolutionary age may still be a factor. Our conclusion from these results indicates that mammalian toxins are following the two-speed model of selection, evolving predominately under diversifying selection, fitting in with other younger venomous taxa like snakes and cone snails-with high amounts of accumulating mutations, leading to more novel adaptions in their toxins.


Assuntos
Quirópteros , Toxinas Biológicas , Animais , Toxinas Biológicas/genética , Toxinas Biológicas/toxicidade , Mamíferos/genética , Peçonhas/genética , Peçonhas/toxicidade , Serpentes , Perfilação da Expressão Gênica , Evolução Molecular
13.
Toxins (Basel) ; 14(12)2022 12 17.
Artigo em Inglês | MEDLINE | ID: mdl-36548781

RESUMO

Biases in snake venom research have been partially identified but seldomly quantified. Using the Google Scholar web search engine, we collected a total of 267 articles published between 1964 and 2021, and reviewed them to assess the main trends in this field of study. We developed a 4-category classification of the harmful potential of each of the 298 snake species retrieved from the analysed publications, and tested whether taxonomy, realm of origin, and/or assigned hazard category could affect how often each of them appeared in the articles considered. Overall, viperids were significantly more represented than any other snake taxon retrieved. The Neotropics were the most represented biogeographic realm for number of studied species, whereas information about the country of origin of the analysed specimens was often incomplete. The vast majority of the publications focused on snake venom characterisation, whereas more ecology-related topics were rarely considered. Hazard category and biogeographic realm of origin of each species had a significant effect on the number of articles dedicated to it, suggesting that a snake's harmful potential and place of origin influence its popularity in venom studies. Our analysis showed an overall positive trend in the number of snake venom studies published yearly, but also underlined severe neglect of snake families of supposedly minor medical relevance (e.g., Atractaspididae), underrepresentation of some of the areas most impacted by snakebite (i.e., Indomalayan and Afrotropic realms), and limited interest in the ecological and functional context of snake venom.


Assuntos
Mordeduras de Serpentes , Venenos de Serpentes , Animais , Venenos de Serpentes/toxicidade , Serpentes , Viés
14.
Proc Biol Sci ; 289(1989): 20221702, 2022 Dec 21.
Artigo em Inglês | MEDLINE | ID: mdl-36515117

RESUMO

Female genitalia are conspicuously overlooked in comparison to their male counterparts, limiting our understanding of sexual reproduction across vertebrate lineages. This study is the first complete description of the clitoris (hemiclitores) in female snakes. We describe morphological variation in size and shape (n = 9 species, 4 families) that is potentially comparable to the male intromittent organs in squamate reptiles (hemipenes). Dissection, diffusible iodine contrast-enhanced micro-CT and histology revealed that, unlike lizard hemiclitores, the snake hemiclitores are non-eversible structures. The two individual hemiclitores are separated medially by connective tissue, forming a triangular structure that extends posteriorly. Histology of the hemiclitores in Australian death adders (Acanthophis antarcticus) showed erectile tissue and strands/bundles of nerves, but no spines (as is found in male hemipenes). These histological features suggest the snake hemiclitores have functional significance in mating and definitively show that the hemiclitores are not underdeveloped hemipenes or scent glands, which have been erroneously indicated in other studies. Our discovery supports that hemiclitores have been retained across squamates and provides preliminary evidence of differences in this structure among snake species, which can be used to further understand systematics, reproductive evolution and ecology across squamate reptiles.


Assuntos
Evolução Biológica , Lagartos , Humanos , Animais , Masculino , Feminino , Austrália , Serpentes/fisiologia , Lagartos/fisiologia , Genitália Masculina , Filogenia
15.
PLoS Negl Trop Dis ; 16(11): e0010915, 2022 11.
Artigo em Inglês | MEDLINE | ID: mdl-36383562

RESUMO

BACKGROUND: Despite domestic production of antivenoms in the Association of Southeast Asian Nations (ASEAN) countries, not all victims with snakebite envenomings indicated for antivenom received the appropriate or adequate effective dose of antivenom due to insufficient supply and inadequate access to antivenoms. We aimed to conduct a cost-effectiveness analysis to project the potential economic and clinical impact of improving access to antivenoms when all snakebite envenomings in ASEAN countries were hypothetically treated with geographically appropriate antivenoms. METHODOLOGY: Using a decision analytic model with input parameters from published literature, local data, and expert opinion, we projected the impact of "full access" (100%) to antivenom, compared to "current access" in five most impacted ASEAN countries, including Indonesia (10%), Philippines (26%), Vietnam (37%), Lao PDR (4%), and Myanmar (64%), from a societal perspective with a lifetime time horizon. Sensitivity analyses were performed. PRINCIPAL FINDINGS: In base-case analyses, full access compared to current access to snake antivenom in the five countries resulted in a total of 9,362 deaths averted (-59%), 230,075 disability-adjusted life years (DALYs) averted (-59%), and cost savings of 1.3 billion USD (-53%). Incremental cost-effectiveness ratios (ICERs) of improving access to antivenom found higher outcomes but lower costs in all countries. Probabilistic sensitivity analyses of 1,000 iterations found that 98.1-100% of ICERs were cost-saving. CONCLUSION/SIGNIFICANCE: Improving access to snake antivenom will result in cost-saving for ASEAN countries. Our findings emphasized the importance of further strengthening regional cooperation, investment, and funding to improve the situation of snakebite victims in ASEAN countries.


Assuntos
Antivenenos , Mordeduras de Serpentes , Animais , Antivenenos/uso terapêutico , Mordeduras de Serpentes/tratamento farmacológico , Análise Custo-Benefício , Serpentes , Ásia
16.
Neuropsychologia ; 177: 108403, 2022 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-36332696

RESUMO

Previous event-related potential (ERP) studies have shown that snake pictures elicit greater early posterior negativity (EPN) compared to other animal pictures. The EPN reflects early selective visual processing of emotionally significant stimuli. Evidence for the role that high and low spatial frequencies play in the early detection of snakes is still inconsistent. The current study aims to clarify this by studying the effect of high and low spatial frequencies on the elevated EPN for snakes separately. Using a rapid serial visual presentation paradigm, participants viewed images of snakes, spiders and birds in three different conditions of filtered spatial frequencies: high spatial frequency, low spatial frequency, and full spatial frequency (the original image). P1 and mean EPN activity in a time window of 225-300 ms after stimulus onset were measured at the occipital cluster (O1, O2, Oz). The results show smaller P1 amplitudes and shorter P1 latencies in response to full-spectrum snake pictures compared to full-spectrum spider and bird pictures, and an increased EPN in response to snake pictures compared to spider and bird pictures in all three filtering conditions. The EPN in response to full-spectrum snake pictures was larger than the EPN in response to filtered snake images. No difference in EPN was found between the snake pictures in the high and low spatial frequency conditions. The results suggest that the roles of high and low spatial frequencies in early automatic attention to snakes are equally important.


Assuntos
Eletroencefalografia , Aranhas , Animais , Estimulação Luminosa , Potenciais Evocados/fisiologia , Serpentes , Percepção Visual/fisiologia , Aves , Emoções
17.
Naturwissenschaften ; 109(6): 56, 2022 Nov 05.
Artigo em Inglês | MEDLINE | ID: mdl-36333469

RESUMO

Viviparity is a widespread reproductive trait in snakes, although fossil evidence bearing on its evolution is extremely sparse. Here, we report an exceptional specimen of the minute booid snake Messelophis variatus recovered in the paleolake of the Messel Formation (early-middle Eocene, Germany). This gravid female contains at least two embryos located in the posterior third of the trunk region. The morphology, size, and degree of ossification of the cranial and postcranial remains indicate they correspond with late embryos. This specimen documents the first occurrence of viviparity in a fossil snake and extends the temporal distribution of this reproductive strategy in booid snakes by over 47 Ma. The evolution of viviparity in squamates has traditionally been associated with cold climates, but its presence at the dawn of the evolution of booids during early Palaeogene thermal peaks indicates that viviparity may have evolved under different selective pressures in this clade.


Assuntos
Nascido Vivo , Serpentes , Animais , Feminino , Gravidez , Serpentes/anatomia & histologia , Fósseis , Crânio/anatomia & histologia , Fenótipo , Evolução Biológica , Viviparidade não Mamífera , Filogenia
18.
Biomolecules ; 12(11)2022 11 17.
Artigo em Inglês | MEDLINE | ID: mdl-36421717

RESUMO

We describe here the purification and cloning of a codon-optimized form of the snake prothrombin activator ecarin from the saw scaled viper (Echis carinatus) expressed in mammalian cells. Expression of recombinant ecarin (rEcarin) was carried out in human embryonic kidney cells (HEK) cells under conditions for the development and performance of a novel and scalable recombinant snake ecarin to industry standards. Clotting performance of the rEcarin was established in recalcified citrated whole blood, plasma, and fresh whole blood and found to be comparable to native ecarin (N-Ecarin). Furthermore, hemolysis was observed with N-Ecarin at relatively high doses in both recalcified citrated and fresh whole blood, while clotting was not observed with rEcarin, providing an important advantage for the recombinant form. In addition, rEcarin effectively clotted both recalcified citrated whole blood and fresh whole blood containing different anticoagulants including heparin, warfarin, dabigatran, Fondaparinux, rivaroxaban and apixaban, forming firm clots in the blood collection tubes. These results demonstrate that rEcarin efficiently clots normal blood as well as blood spiked with high concentrations of anticoagulants and has great potential as an additive to blood collection tubes to produce high quality serum for analyte analysis in diagnostic medicine.


Assuntos
Endopeptidases , Protrombina , Trombose , Venenos de Víboras , Animais , Humanos , Anticoagulantes/farmacologia , Protrombina/metabolismo , Serpentes , Tromboplastina , Venenos de Víboras/farmacologia , Endopeptidases/farmacologia
19.
Toxins (Basel) ; 14(11)2022 Nov 11.
Artigo em Inglês | MEDLINE | ID: mdl-36422961

RESUMO

Lebetin 2 (L2), a natriuretic-like peptide (NP), exerts potent cardioprotection in myocardial infarction (MI), with stronger effects than B-type natriuretic peptide (BNP). To determine the molecular mechanisms underlying its cardioprotection effect, we used molecular modeling, molecular docking and molecular dynamics (MD) simulation to describe the binding mode, key interaction residues as well as mechanistic insights into L2 interaction with NP receptors (NPRs). L2 binding affinity was determined for human, rat, mouse and chicken NPRs, and the stability of receptor-ligand complexes ascertained during 100 ns-long MD simulations. We found that L2 exhibited higher affinity for all human NPRs compared to BNP, with a rank preference for NPR-A > NPR-C > NPR-B. Moreover, L2 affinity for human NPR-A and NPR-C was higher in other species. Both docking and MD studies revealed that the NPR-C-L2 interaction was stronger in all species compared to BNP. Due to its higher affinity to human receptors, L2 could be used as a therapeutic approach in MI patients. Moreover, the stronger interaction of L2 with NPR-C could highlight a new L2 signaling pathway that would explain its additional effects during cardiac ischemia. Thus, L2 is a promising candidate for drug design toward novel compounds with high potency, affinity and stability.


Assuntos
Peptídeo Natriurético Encefálico , Peptídeos , Venenos de Víboras , Animais , Humanos , Camundongos , Ratos , Isquemia , Simulação de Acoplamento Molecular , Peptídeos/química , Serpentes , Venenos de Víboras/química
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