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1.
Sci Rep ; 12(1): 7139, 2022 May 03.
Artigo em Inglês | MEDLINE | ID: mdl-35504946

RESUMO

Animal movement can impact human-wildlife conflict by influencing encounter and detection rates. We assess the movement and space use of the highly venomous and medically important Malayan krait (Bungarus candidus) on a suburban university campus. We radio-tracked 14 kraits for an average of 114 days (min: 19, max: 218), during which we located individuals an average of 106 times (min: 21, max: 229) each. Most individuals displayed some level of attraction to buildings (n = 10) and natural areas (n = 12); we identified a similar unambiguous pattern of attraction to buildings and natural areas at the population level (of our sample). Snakes remained in shelter sites for long durations (max: 94 days) and revisited sites on average every 15.45 days. Over 50% of locations were within human settlements and 37.1% were associated with buildings. We found generally seasonal patterns of activity, with higher activity in wet seasons, and lower activity in the hot season. These results show frequent proximity between Malayan kraits and humans at the university; thereby, suggesting a near constant potential for human-wildlife conflict. Despite the fact that no snakebites from this species occurred at the university during our study period, substantial education and awareness training should be considered to ensure continued coexistence on campus.


Assuntos
Bungarus , Mordeduras de Serpentes , Animais , Humanos , Mordeduras de Serpentes/epidemiologia , Serpentes
2.
Zootaxa ; 5120(3): 449-450, 2022 Mar 28.
Artigo em Inglês | MEDLINE | ID: mdl-35391155

RESUMO

Body size is perhaps the most important trait for organism biologists, as it is associated with a myriad of ecological, evolutionary, behavioral, morphological, physiological and life-history aspects (e.g., rates of molecular evolution, metabolic rates, predation, reproduction), and with extinction risk. There are, however, several measures commonly used to quantify organism body size. Within ectothermic tetrapods, the most common measures include snout-vent length (SVL, mostly in lizards), and total length (TL, in most snakes). In endotherms, however, and especially in mammals, body mass is the most common measure of size.


Assuntos
Lagartos , Répteis , Anfíbios , Animais , Tamanho Corporal , Mamíferos/anatomia & histologia , Répteis/anatomia & histologia , Serpentes
3.
Zootaxa ; 5105(4): 490-500, 2022 Mar 07.
Artigo em Inglês | MEDLINE | ID: mdl-35391290

RESUMO

In two different publications, William Theobald described, during the same year (1868), two taxa at species level in the snake genus Pareas, namely Pareas macularius and Pareas berdmorei, both based on the same syntypes. However, these two taxa are distinct at species level. We here discuss these descriptions, especially that of P. berdmorei which might have raised a nomenclatural problem. We examined their respective type specimens and we here designate a lectotype for Pareas macularius.


Assuntos
Lagartos , Serpentes , Animais
4.
Zootaxa ; 5099(2): 221-243, 2022 Feb 11.
Artigo em Inglês | MEDLINE | ID: mdl-35391417

RESUMO

Recent integrative taxonomic studies of the agamid genus Acanthocercus Fitzinger, 1843 have shown that Angola harbors three different taxa, all within the Acanthocercus atricollis (Smith, 1849) species complexA. cyanocephalus (Falk, 1925) in the northeastern parts of the country, A. margaritae Wagner et al. 2021 in the southern regions, and an unnamed species in the central and northwestern parts of Angola. Using the previously published molecular data as evidence of phylogenetic support and newly collected morphological, meristic and coloration data, we here describe this unnamed lineage as a new species. The new species is morphologically very similar to A. cyanocephalus, but it can easily be differentiated from the latter by the coloration pattern of displaying males, with a blue coloration restricted to the head region, and by its inferior scale counts compared to other species of the A. atricollis complex group. As reported in other studies in this group, male breeding coloration is an effective trait for diagnosing these morphologically conserved species. This description raises the number of Acanthocercus species recognized to 15 and is another contribution revealing the rich but still incompletely described herpetological diversity of Angola.


Assuntos
Lamiaceae , Lagartos , Angola , Animais , Masculino , Filogenia , Melhoramento Vegetal , Serpentes
5.
Zootaxa ; 5099(2): 201-220, 2022 Feb 11.
Artigo em Inglês | MEDLINE | ID: mdl-35391418

RESUMO

A new species of Diploderma is described from the upper Salween River Valley in eastern Tibet, China based on morphological and genetic data. The new species is morphologically most similar and phylogenetically closely related to D. laeviventre, but it can be easily diagnosed by having distinct conical scales on the post rictal region of the head, distinctively keeled ventral head and body scales, and different coloration of gular spots and dorsolateral stripes in both sexes. The taxonomic discovery further highlights the underestimated diversity of the genus and the importance of habitat conservation of the neglected hot-dry valley ecosystems in the Hengduan Mountain Region of China.


Assuntos
Lagartos , Rios , Distribuição Animal , Animais , China , Ecossistema , Feminino , Masculino , Filogenia , Serpentes , Tibet
6.
Parasitol Int ; 89: 102587, 2022 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-35452797

RESUMO

Although Brazil is a hotspot for snake species, there is a lack of information on the biodiversity of haemoparasites infecting these hosts. Thus, the present study aimed to bring new insights on the diversity of species of Hepatozoon (Apicomplexa: Adeleorina: Hepatozoidae) infecting Brazilian snakes from the Midwest and Southeast regions. The snakes were captured from 2018 to 2020 from the states of Mato Grosso, Mato Grosso do Sul, Goiás, and São Paulo. Three to five blood smears were made and the remaining blood sample was stored for further molecular analysis. Moreover, histopathological slides of the organs were stained with haematoxylin-eosin. Regarding molecular diagnosis, PCR was performed targeting different regions of the 18S rRNA gene of apicomplexan parasites. From the 13 free-living snakes screened, ten (76.92%) were found infected with Hepatozoon spp. Based on morphological and morphometric tools, five different morphotypes of species of Hepatozoon gamonts were detected. Molecular data and phylogenetic analysis support the morphological data, identifying five species of Hepatozoon from snakes, of which three species belong to previously described species, Hepatozoon cevapii, Hepatozoon cuestensis, and Hepatozoon quagliattus, with a genetic similarity of 100% (based on the 18S rRNA genetic marker). The present study identifies and describes two new species of Hepatozoon, Hepatozoon annulatum sp. nov. infecting the snake Leptodeira annulata and Hepatozoon trigeminum sp. nov. infecting the snake Oxyrhopus trigeminus. Thus, based on morphological and molecular data the present study provides new insights on haemogregarine diversity infecting Brazilian snakes from the Midwest and Southeast regions.


Assuntos
Apicomplexa , Coccidiose , Eucoccidiida , Parasitos , Animais , Apicomplexa/genética , Brasil/epidemiologia , Coccidiose/parasitologia , Coccidiose/veterinária , Eucoccidiida/genética , Parasitos/genética , Filogenia , RNA Ribossômico 18S/genética , Serpentes/parasitologia
7.
J Evol Biol ; 35(5): 708-718, 2022 05.
Artigo em Inglês | MEDLINE | ID: mdl-35384114

RESUMO

Blood oxygen-carrying capacity is shaped both by the ambient oxygen availability as well as species-specific oxygen demand. Erythrocytes are a critical part of oxygen transport and both their size and shape can change in relation to species-specific life-history, behavioural or ecological conditions. Here, we test whether components of the environment (altitude), life history (reproductive mode, body temperature) and behaviour (diving, foraging mode) drive erythrocyte size variation in the Lepidosauria (lizards, snakes and rhynchocephalians). We collected data on erythrocyte size (area) and shape (L/W: elongation ratio) from Lepidosauria across the globe (N = 235 species). Our analyses show the importance of oxygen requirements as a driver of erythrocyte size. Smaller erythrocytes were associated with the need for faster delivery (active foragers, high-altitude species, warmer body temperatures), whereas species with greater oxygen demands (diving species, viviparous species) had larger erythrocytes. Erythrocyte size shows considerable cross-species variation, with a range of factors linked to the oxygen delivery requirements being major drivers of these differences. A key future aspect for study would include within-individual plasticity and how changing states, for example, pregnancy, perhaps alter the size and shape of erythrocytes in Lepidosaurs.


Assuntos
Lagartos , Viviparidade não Mamífera , Animais , Eritrócitos , Oviparidade , Oxigênio , Serpentes
8.
J Therm Biol ; 105: 103204, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-35393045

RESUMO

Semi-aquatic north-temperate reptiles experience challenging environmental conditions for thermoregulation on both seasonal and daily bases. We studied the thermal biology of north-temperate Northern Water Snakes (Nerodia sipedon) in central Michigan by remote radiotelemetry monitoring of snake body temperature (Tb) using surgically implanted thermally-sensitive radio-transmitters and by measuring operative temperatures (Te) across a range of microhabitats using biophysical models. Our goals included evaluation of thermoregulatory capabilities at a locality that we viewed to be a fine-grained thermal environment, seasonal variations in patterns of thermoregulation, and the effects of sex on thermoregulation. During summer, snakes showed diel Tb cycling apparently using the open Sphagnum mat for late morning warming and shuttling among different microhabitats until early evening when a monotonic decline in Tb ensued and continued through the early morning hours. Snakes attained Tb within their laboratory-determined preferred body temperature range (Tset = 28-33 °C) mostly during late afternoon and with average percentages of Tb values for individual snakes within Tset range when permitted by operative temperatures (Ex) between 68 and 70% of the time depending on method of measurement. Relatively high investment in thermoregulation when thermal conditions were poor occurred only during September but declined thereafter as snakes prepared to overwinter. We did not detect differences in thermoregulation among reproductive females, non-reproductive females, and males. Relative to a population of N. sipedon at a higher latitude in Ontario our snakes showed a relatively high Tset range and thermoregulated more effectively, particularly during the daylight hours. It remains unclear how much inter-population variation in thermoregulation is due to potential adaptations to latitude, to habitat differences, or variations in methodologies.


Assuntos
Colubridae , Animais , Regulação da Temperatura Corporal/fisiologia , Feminino , Masculino , Michigan , Estações do Ano , Serpentes , Áreas Alagadas
9.
Mol Biol Evol ; 39(4)2022 Apr 10.
Artigo em Inglês | MEDLINE | ID: mdl-35413123

RESUMO

Understanding the joint roles of protein sequence variation and differential expression during adaptive evolution is a fundamental, yet largely unrealized goal of evolutionary biology. Here, we use phylogenetic path analysis to analyze a comprehensive venom-gland transcriptome dataset spanning three genera of pitvipers to identify the functional genetic basis of a key adaptation (venom complexity) linked to diet breadth (DB). The analysis of gene-family-specific patterns reveals that, for genes encoding two of the most important venom proteins (snake venom metalloproteases and snake venom serine proteases), there are direct, positive relationships between sequence diversity (SD), expression diversity (ED), and increased DB. Further analysis of gene-family diversification for these proteins showed no constraint on how individual lineages achieved toxin gene SD in terms of the patterns of paralog diversification. In contrast, another major venom protein family (PLA2s) showed no relationship between venom molecular diversity and DB. Additional analyses suggest that other molecular mechanisms-such as higher absolute levels of expression-are responsible for diet adaptation involving these venom proteins. Broadly, our findings argue that functional diversity generated through sequence and expression variations jointly determine adaptation in the key components of pitviper venoms, which mediate complex molecular interactions between the snakes and their prey.


Assuntos
Venenos de Serpentes , Serpentes , Adaptação Fisiológica/genética , Animais , Dieta , Filogenia , Venenos de Serpentes/genética , Serpentes/metabolismo
10.
J Exp Biol ; 225(7)2022 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-35363854

RESUMO

The venom glands of reptiles, particularly those of front-fanged advanced snakes, must satisfy conflicting biological demands: rapid synthesis of potentially labile and highly toxic proteins, storage in the gland lumen for long periods, stabilization of the stored secretions, immediate activation of toxins upon deployment and protection of the animal from the toxic effects of its own venom. This dynamic system could serve as a model for the study of a variety of different phenomena involving exocrine gland activation, protein synthesis, stabilization of protein products and secretory mechanisms. However, these studies have been hampered by a lack of a long-term model that can be propagated in the lab (as opposed to whole-animal studies). Numerous attempts have been made to extend the lifetime of venom gland secretory cells, but only recently has an organoid model been shown to have the requisite qualities of recapitulation of the native system, self-propagation and long-term viability (>1 year). A tractable model is now available for myriad cell- and molecular-level studies of venom glands, protein synthesis and secretion. However, venom glands of reptiles are not identical, and many differ very extensively in overall architecture, microanatomy and protein products produced. This Review summarizes the similarities among and differences between venom glands of helodermatid lizards and of rear-fanged and front-fanged snakes, highlighting those areas that are well understood and identifying areas where future studies can fill in significant gaps in knowledge of these ancient, yet fascinating systems.


Assuntos
Lagartos , Venenos de Serpentes , Animais , Glândulas Exócrinas/metabolismo , Lagartos/metabolismo , Glândulas Salivares/metabolismo , Venenos de Serpentes/metabolismo , Serpentes
11.
Gigascience ; 112022 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-35365832

RESUMO

Snake venoms represent a danger to human health, but also a gold mine of bioactive proteins that can be harnessed for drug discovery purposes. The evolution of snakes and their venom has been studied for decades, particularly via traditional morphological and basic genetic methods alongside venom proteomics. However, while the field of genomics has matured rapidly over the past 2 decades, owing to the development of next-generation sequencing technologies, snake genomics remains in its infancy. Here, we provide an overview of the state of the art in snake genomics and discuss its potential implications for studying venom evolution and toxinology. On the basis of current knowledge, gene duplication and positive selection are key mechanisms in the neofunctionalization of snake venom proteins. This makes snake venoms important evolutionary drivers that explain the remarkable venom diversification and adaptive variation observed in these reptiles. Gene duplication and neofunctionalization have also generated a large number of repeat sequences in snake genomes that pose a significant challenge to DNA sequencing, resulting in the need for substantial computational resources and longer sequencing read length for high-quality genome assembly. Fortunately, owing to constantly improving sequencing technologies and computational tools, we are now able to explore the molecular mechanisms of snake venom evolution in unprecedented detail. Such novel insights have the potential to affect the design and development of antivenoms and possibly other drugs, as well as provide new fundamental knowledge on snake biology and evolution.


Assuntos
Genômica , Venenos de Serpentes , Animais , Genoma , Répteis/genética , Venenos de Serpentes/genética , Serpentes/genética
12.
Toxins (Basel) ; 14(4)2022 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-35448856

RESUMO

Venomic research, powered by techniques adapted from proteomics, transcriptomics, and genomics, seeks to unravel the diversity and complexity of venom through which knowledge can be applied in the treatment of envenoming, biodiscovery, and conservation. Snake venom proteomics is most extensively studied, but the methods varied widely, creating a massive amount of information which complicates data comparison and interpretation. Advancement in mass spectrometry technology, accompanied by growing databases and sophisticated bioinformatic tools, has overcome earlier limitations of protein identification. The progress, however, remains challenged by limited accessibility to samples, non-standardized quantitative methods, and biased interpretation of -omic data. Next-generation sequencing (NGS) technologies enable high-throughput venom-gland transcriptomics and genomics, complementing venom proteomics by providing deeper insights into the structural diversity, differential expression, regulation and functional interaction of the toxin genes. Venomic tissue sampling is, however, difficult due to strict regulations on wildlife use and transfer of biological materials in some countries. Limited resources for techniques and funding are among other pertinent issues that impede the progress of venomics, particularly in less developed regions and for neglected species. Genuine collaboration between international researchers, due recognition of regional experts by global organizations (e.g., WHO), and improved distribution of research support, should be embraced.


Assuntos
Venenos de Serpentes , Serpentes , Animais , Espectrometria de Massas , Proteômica/métodos , Venenos de Serpentes/química , Venenos de Serpentes/genética , Serpentes/genética , Transcriptoma
13.
Toxins (Basel) ; 14(3)2022 02 24.
Artigo em Inglês | MEDLINE | ID: mdl-35324665

RESUMO

Snake envenoming afflicts the Indian subcontinent with the highest rates of mortality (47,000) and morbidity globally. The only effective treatment for snakebites is the administration of antivenom, which is produced by the hyperimmunisation of equines. Commercial Indian antivenoms, however, have been shown to exhibit a poor preclinical performance in neutralising venom, as a result of inter- and intrapopulation snake venom variation. Additionally, their poor dose effectiveness necessitates the administration of larger volumes of antivenom for treatment, leading to several harmful side effects in snakebite victims, including serum sickness and fatal anaphylaxis. In this study, we employed chromatographic purification to enhance the dose efficacy of commercial Indian antivenoms. The efficacy of this 'second-generation' antivenom was comparatively evaluated against six other marketed antivenoms using a number of in vitro and in vivo preclinical assays, which revealed its superior venom recognition capability. Enhanced purity also resulted in significant improvements in dose effectiveness, as the 'second-generation' antivenom exhibited a 3 to 4.5 times increased venom neutralisation potential. Furthermore, preclinical assays revealed the increased effectiveness of the 'second-generation' antivenom in countering morbid effects inflicted by the 'big four' Indian snakes. Thus, we demonstrate the role of simpler purification steps in significantly enhancing the effectiveness of snakebite therapy in regions that are most affected by snakebites.


Assuntos
Antivenenos , Mordeduras de Serpentes , Animais , Antivenenos/química , Antivenenos/uso terapêutico , Cavalos , Índia , Mordeduras de Serpentes/tratamento farmacológico , Venenos de Serpentes/química , Serpentes
14.
J Exp Biol ; 225(6)2022 03 15.
Artigo em Inglês | MEDLINE | ID: mdl-35325925

RESUMO

The evolution of constriction and of large prey ingestion within snakes are key innovations that may explain the remarkable diversity, distribution and ecological scope of this clade, relative to other elongate vertebrates. However, these behaviors may have simultaneously hindered lung ventilation such that early snakes may have had to circumvent these mechanical constraints before those behaviors could evolve. Here, we demonstrate that Boa constrictor can modulate which specific segments of ribs are used to ventilate the lung in response to physically hindered body wall motions. We show that the modular actuation of specific segments of ribs likely results from active recruitment or quiescence of derived accessory musculature. We hypothesize that constriction and large prey ingestion were unlikely to have evolved without modular lung ventilation because of their interference with lung ventilation, high metabolic demands and reliance on sustained lung convection. This study provides a new perspective on snake evolution and suggests that modular lung ventilation evolved during or prior to constriction and large prey ingestion, facilitating snakes' remarkable radiation relative to other elongate vertebrates.


Assuntos
Boidae , Animais , Boidae/fisiologia , Pulmão , Serpentes
16.
J Wildl Dis ; 58(2): 290-297, 2022 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-35245359

RESUMO

Ophidiomyces ophidiicola is an emerging fungal pathogen associated with infections in snakes across North America. Although documented in Pennsylvania, O. ophidiicola has not been found at Powdermill Nature Reserve (PNR) in southwestern Pennsylvania, where the snake assemblage has been studied since 2002 and several species have recently declined. We surveyed for O. ophidiicola and putative ophidiomycosis at PNR. We screened five species of free-ranging, wild snakes (n=34) for suspected ophidiomycosis by visually checking for dermatitis and swabbing for the presence of O. ophidiicola DNA. We found a moderate prevalence of snakes with skin lesions (n=15) but a low prevalence of snakes with O. ophidiicola DNA in traditional PCR assays (n=2). Both positive snakes belonged to the same species and only one presented with lesions. When quantitative PCR screens were performed on duplicate swabs, 19 snakes were positive for O. ophidiicola DNA, with positive individuals in two species. Mark-recapture methods revealed seasonal variability in disease dynamics for sampled snakes. One individual presented with less than five skin lesions and tested negative in May 2020, had more than five lesions with a high fungal DNA load in June 2020, and no lesions with a low fungal DNA load in July 2020. We also found that snakes sampled from under the same cover object at the same time either all tested positive or all negative, including one instance involving two species. Our results underscore the value of using multiple screening techniques for O. ophidiicola surveillance and repeated sampling of individuals to understand the dynamics of ophidiomycosis in wild populations as compared to single method and single timepoint approaches.


Assuntos
Onygenales , Animais , DNA Fúngico , Pennsylvania/epidemiologia , Serpentes/microbiologia
20.
Environ Toxicol Chem ; 41(3): 758-770, 2022 03.
Artigo em Inglês | MEDLINE | ID: mdl-35112731

RESUMO

Mercury (Hg) and radiocesium (137 Cs) are well-known environmental contaminants with the potential to impact the health of humans and wildlife. Snakes have several characteristics conducive to studying environmental contamination but have rarely been included in the monitoring of polluted sites. We investigated the bioaccumulation of Hg and 137 Cs and associations with sublethal effects (standard metabolic rate [SMR] and hemoparasite infections) in Florida green watersnakes (Nerodia floridana). We captured 78 snakes from three former nuclear cooling reservoirs on the US Department of Energy's Savannah River Site in South Carolina (USA). For captured snakes, we (1) determined whole-body 137 Cs, (2) quantified total Hg (THg) using snake tail clips, (3) conducted hemoparasite counts, and (4) measured the SMR. We used multiple regression models to determine associations among snake body size, capture location, sex, tail THg, whole-body 137 Cs, Hepatozoon spp. prevalence and parasitemia, and SMR. Average whole-body 137 Cs (0.23 ± 0.08 Becquerels [Bq]/g; range: 0.00-1.02 Bq/g) was correlated with snake body size and differed significantly by capture site (Pond B: 0.67 ± 0.05 Bq/g; Par Pond: 0.10 ± 0.02 Bq/g; Pond 2: 0.03 ± 0.02 Bq/g). Tail THg (0.33 ± 0.03 mg/kg dry wt; range: 0.16-2.10 mg/kg) was significantly correlated with snake body size but did not differ by capture site. We found no clear relationship between SMR and contaminant burdens. However, models indicated that the prevalence of Hepatozoon spp. in snakes was inversely related to increasing whole-body 137 Cs burdens. Our results indicate the bioaccumulation of Hg and 137 Cs in N. floridana and further demonstrate the utility of aquatic snakes as bioindicators. Our results also suggest a decrease in Hepatozoon spp. prevalence related to increased burdens of 137 Cs. Although the results are intriguing, further research is needed to understand the dynamics between 137 Cs and Hepatozoon spp. infections in semiaquatic snakes. Environ Toxicol Chem 2022;41:758-770. © 2022 SETAC.


Assuntos
Mercúrio , Animais , Biomarcadores Ambientais , Monitoramento Ambiental , Florida , Humanos , Mercúrio/análise , Rios , Serpentes/metabolismo
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