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1.
Sci Total Environ ; 855: 158864, 2023 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-36169021

RESUMO

Stressful situations induce an increase in the production of reactive oxygen species (ROS) which can lead to molecular damage and alteration of cell function. The introduction of new potential predators induces physiological stress in native fauna. However, behavioral responses have been reported in preys, demonstrating an induction of the defenses against alien species. Behavioral and antioxidant enzyme responses in the moorish gecko, Tarentola mauritanica, against the invasive predator horseshoe whip snake (Hemorrhois hippocrepis) were assessed. Behavior was recorded and a tissue sample from the tail was collected after placing the gecko in a terrarium with previous absence or presence of the snake in 'Control' and 'H. hippocrepis' groups, respectively. Fifteen behavioral variables were examined, including tongue flick (TF) and locomotion patterns. Antioxidant enzyme activities -catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione reductase (GR)-, and the levels of reduced (GSH) and oxidized glutathione (GSSG), glutathione/glutathione disulfide ratio (GSH/GSSG) and malondialdehyde (MDA) concentrations were measured in the tissue sampled. Geckos exposed to the snake's odor showed a higher number of TF, longer amounts of time remaining motionless or moving in slow motion and they spent less time on the ground in comparison to the 'Control' group. The presence of the snake produced a significant increase in the activities of CAT, SOD and GR and a decrease in the GSH/GSSG ratio in T. mauritanica individuals exposed to the snake's scent. Thus, both behavioral responses and oxidative stress biomarkers clearly showed that T. mauritanica is able to recognize H. hippocrepis as a potential predator, despite being a recently introduced snake at the Balearic Islands.


Assuntos
Colubridae , Lagartos , Animais , Dissulfeto de Glutationa , Antioxidantes/metabolismo , Lagartos/metabolismo , Catalase/metabolismo , Glutationa Redutase/metabolismo , Estresse Oxidativo/fisiologia , Glutationa Peroxidase/metabolismo , Superóxido Dismutase/metabolismo , Glutationa/metabolismo , Colubridae/metabolismo
2.
Toxicon ; 218: 19-24, 2022 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-36057394

RESUMO

Venoms are evolutionary novelties that have real-world implications due to their impact upon human health. However, relative to the abundant studies of elapid and viperid snake venoms, fewer investigations have been undertaken on those of rear-fanged snakes as they are more problematic for obtaining venom. While most rear-fanged venomous snakes are not considered to be of great medical importance, several species are capable of producing fatalities. Most notable among these are snakes from the genus Rhabdophis, the Asian "keelback" snakes. Prior work have described potent procoagulant toxicity suggesting Factor X and prothrombin activation, but did not investigate the ability to activate other clotting factors. Here we show that in addition to activating both Factor X and prothrombin (with prothrombin twice that of FX), the venom of Rhabdophis subminiatus is able to more potently activate Factor VII (ten times that of prothrombin), while also activating FXII and FIX equipotently to prothrombin, and with FXI also activated but at a much lower level. The ability to activate FVII represents a third convergent evolution of this trait. The Australian elapid clade of [Oxyuranus (taipans) + Pseudonaja (brown snakes)] was the first identified to have evolved this trait. and only recently was it shown to be independently present in another lineage (the Central American viperid species Porthidium volcanicum). In addition, the abilities to activate FXI and FXII are also convergent between R. subminiatus and P. volcanicum, but with R. subminiatus being much more potent. By testing across amphibian, avian, and mammalian plasmas we demonstrate that the venom is potently procoagulant across diverse plasma types. However, consistent with dietary preference, R. subminiatus venom was most potent upon amphibian plasma. While a Rhabdophis antivenom is produced in Japan to treat R. tigrinus envenomings, it is scarce even within Japan and is not exported. As this genus is very wide-ranging in Asia, alternate treatment options are in need of development. Hence we tested the ability of candidate, broad-spectrum enzyme inhibitors to neutralize R. subminiatus venom: marimastat was more effective than prinomastat but both marimastat and prinomastat were significantly more effective than DMPS (2,3-Dimercapto-1-propanesulfonic acid). The findings of this study shed light on the evolution of these fascinating rear-fanged snakes as well as explored their systemic effects upon blood coagulation and point to potential treatment options for the rare, but potentially lethal encounters.


Assuntos
Antivenenos , Colubridae , Animais , Antivenenos/farmacologia , Austrália , Coagulação Sanguínea , Fatores de Coagulação Sanguínea/metabolismo , Fatores de Coagulação Sanguínea/farmacologia , Elapidae/metabolismo , Fator VII/metabolismo , Fator VII/farmacologia , Fator X/metabolismo , Fator X/farmacologia , Humanos , Ácidos Hidroxâmicos , Mamíferos , Compostos Orgânicos , Protrombina , Venenos de Serpentes/farmacologia , Unitiol/metabolismo , Unitiol/farmacologia
3.
Curr Biol ; 32(18): R939-R940, 2022 09 26.
Artigo em Inglês | MEDLINE | ID: mdl-36167038

RESUMO

Catania provides an introduction to tentacled snakes and their ingenious ability to capture fish.


Assuntos
Colubridae , Animais , Peixes , Serpentes
4.
Parasitol Res ; 121(12): 3523-3527, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-36171408

RESUMO

A probe-hybridization quantitative polymerase chain reaction assay specific for Cryptosporidium serpentis (qPCR) has been developed and shown to be extremely sensitive in the laboratory, but clinical sensitivity and specificity for this test are lacking. To approximate the sensitivity and specificity of the C. serpentis qPCR, the medical records from a captive snake colony were reviewed, and between November 2015 and June 2021, 63 eastern indigo snakes (Drymarchon couperi) were necropsied. Of these 63 snakes, 11 had qPCR performed on gastric biopsies collected at the time of necropsy, 8 had qPCR performed on samples collected by gastric swab within 35 days of necropsy, and 34 had qPCR performed on samples collected by cloacal swab within 84 days of necropsy. The qPCR results were then compared to the post-mortem histological findings, where all three sampling techniques had a 100% specificity. The sensitivity was highest in samples collected at necropsy (100%, CI: 63.06 - 100%) followed by the ante-mortem testing: gastric swab (87.50%, CI: 42.13 - 99.64%) and cloacal swab (66.67%, CI: 44.68 - 84.37%).


Assuntos
Colubridae , Criptosporidiose , Cryptosporidium , Animais , Humanos , Cryptosporidium/genética , Serpentes , Reação em Cadeia da Polimerase em Tempo Real , Estômago
5.
Zootaxa ; 5154(2): 175-197, 2022 Jun 14.
Artigo em Inglês | MEDLINE | ID: mdl-36095629

RESUMO

Based on 85 examined specimens, photographs of living specimens and illustrations published in the literature, we refine the distribution ranges of both Gonyosoma prasinum (Blyth, 1854) and of the recently described species Gonyosoma coeruleum Liu, Hou, Ye Htet Lwin, Wang Rao, 2021, which was not clearly addressed in its original description. We also redescribe the syntypes of Coluber prasinus Blyth, 1854 and the holotype of Gonyosoma gramineum Gnther, 1864, we discuss the status of this latter taxon, and we describe the hemipenial morphology of G. coeruleum.


Assuntos
Colubridae , Lagartos , Animais , Lagartos/anatomia & histologia
6.
Zootaxa ; 5153(1): 1-69, 2022 Jun 10.
Artigo em Inglês | MEDLINE | ID: mdl-36095641

RESUMO

The Neotropical parrot snake genus Leptophis comprises a group of 12 colubrine snakes widely distributed in Mexico, Central- and South America. Among the currently recognized taxa in the genus, L. ahaetulla constitutes a morphologically diverse assemblage of typically slender snakes, with subspecies recorded from Mexico to most of South America. Though extremely variable in scalation, coloration, size and dentition, many of these subspecies are still poorly known, with at least three being known from few specimens, hampering the diagnosability and determination of the taxonomic status of certain populations. Accumulation of new specimens and new analytical approach for species delimitation supported a comprehensive taxonomic revision of these snakes based on the examination of meristic, morphometric, color pattern and hemipenial characters of 1625 specimens. Accordingly, the following taxa are herein referred to as full species: L. a. ahaetulla, L. a. bocourti, L. a. bolivianus, L. a. liocercus, L. a. marginatus, L. a. nigromarginatus, L. a. occidentalis, L. a. praestans and L. a. urostictus. Moreover, L. a. ortoni is placed in the synonymy of L. nigromarginatus, whereas L. coeruleodorsus, a former subspecies recently elevated to species rank, is redescribed, and L. haileyi is placed in the synonymy of this latter taxon. In addition, a dichotomous key including all recognized species of Leptophis is provided.


Assuntos
Colubridae , Papagaios , Animais
7.
Zootaxa ; 5138(4): 417-430, 2022 May 19.
Artigo em Inglês | MEDLINE | ID: mdl-36095827

RESUMO

We report the rediscovery of Oligodon melaneus 112 years after its original description and document the third, and only non-type, specimen for the species. The new specimen was found 267 km east of the type locality (Tindharia, West Bengal state) from Assam state, India. We designate a lectotype for the species, and provide an extended description of a freshly collected male specimen. Phylogenetic analyses of 16s and cytb mitochondrial genes provide support for O. melaneus being closely related to the widespread South Asian endemic O. arnensis.


Assuntos
Colubridae , Animais , Colubridae/genética , Genes Mitocondriais , Índia , Masculino , Filogenia
8.
Toxicon ; 217: 41-45, 2022 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-35940358

RESUMO

The mixed quality evidence about non-front-fanged snake bites has included unsupported speculation and presumption; the possible role of atopy and/or primary hypersensitivity have often been prematurely discounted. Described is a medically insignificant bite by a captive African emerald snake, Hapsidophrys smaragdinus Schlegel, 1837 (Colubridae, Colubrinae) that caused the development of moderate Type IV hypersensitivity; the 44-year-old male victim experienced persistent pruritis and an erythematous bite site maculopapular dermatitis that slowly resolved and required 6 days for full resolution. The victim had received several previous medically insignificant bites from non-front-fanged snakes. Brief comparison is made with a previously reported case consistent with a mixed clinical picture of local mild envenoming and hypersensitivity from a bite by another colubrine, the coin snake (Hemmorhois nummifer). This case highlights slowly accumulating evidence supporting the risk of acquired and primary hypersensitivity to some snakebites in susceptible individuals. In order to provide accurate medical risk profiles for less-known snake species it is essential that the case of any patient developing acute or delayed effects from bites by these species is formally documented. The need for further attention to atopic risks, especially in private collectors, is emphasised with consideration of venom/other ophidian product-induced anaphylaxis.


Assuntos
Colubridae , Dermatite Atópica , Mordeduras de Serpentes , Adulto , Animais , Documentação , Humanos , Masculino , Mordeduras de Serpentes/veterinária , Venenos de Serpentes
9.
J Hered ; 113(6): 632-640, 2022 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-35939354

RESUMO

The glossy snake (Arizona elegans) is a polytypic species broadly distributed across southwestern North America. The species occupies habitats ranging from California's coastal chaparral to the shortgrass prairies of Texas and southeastern Nebraska, to the extensive arid scrublands of central México. Three subspecies are currently recognized in California, one of which is afforded state-level protection based on the extensive loss and modification of its preferred alluvial coastal scrub and inland desert habitat. We report the first genome assembly of A. elegans occidentalis as part of the California Conservation Genomics Project (CCGP). Consistent with the reference genome strategy of the CCGP, we used Pacific Biosciences HiFi long reads and Hi-C chromatin-proximity sequencing technologies to produce a de novo assembled genome. The assembly comprises a total of 140 scaffolds spanning 1,842,602,218 base pairs, has a contig NG50 of 61 Mb, a scaffold NG50 of 136 Mb, and a BUSCO complete score of 95.9%, and is one of the most complete snake genome assemblies. The A. e. occidentalis genome will be a key tool for understanding the genomic diversity and the basis of adaptations within this species and close relatives within the hyperdiverse snake family Colubridae.


Assuntos
Colubridae , Animais , Colubridae/genética , Arizona , Genômica , Genoma , Cromossomos
10.
Toxins (Basel) ; 14(8)2022 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-36006190

RESUMO

Snake venom is an adaptive ecological trait that has evolved primarily as a form of prey subjugation. Thus, the selection pressure for toxin diversification is exerted by the prey's physiological targets, with this pressure being particularly acute for specialist feeders, such as the King Cobra species, all of which are snake-prey specialists. However, while extensive research has been undertaken to elucidate key amino acids that guide toxin structure-activity relationships, reciprocal investigations into the specific sites guiding prey-lineage selective effects have been lacking. This has largely been due to the lack of assay systems amenable to systematic amino acid replacements of targeted proteins in the prey's physiological pathways. To fill this knowledge gap, we used a recently described approach based upon mimotope peptides corresponding to the orthosteric site of nicotinic acetylcholine receptor alpha-1 subunits, a major binding site for snake venom neurotoxins that cause flaccid paralysis. We investigated the venoms of four different types of King Cobra (Cambodian, Javan, Malaysian, and Thai). This approach allowed for the determination of the key amino acid positions in King Cobra snake prey that are selectively bound by the toxins, whereby replacing these amino acids in the snake-prey orthosteric site with those from lizards or rats resulted in a significantly lower level of binding by the venoms, while conversely replacing the lizard or rat amino acids with those from the snake at that position increased the binding. By doing such, we identified three negatively charged amino acids in the snake orthosteric site that are strongly bound by the positively charged neurotoxic three-finger toxins found in King Cobra venom. This study, thus, sheds light on the selection pressures exerted by a specialist prey item for the evolution of lineage-selective toxins.


Assuntos
Colubridae , Lagartos , Receptores Nicotínicos , Toxinas Biológicas , Aminoácidos/metabolismo , Animais , Colubridae/metabolismo , Venenos Elapídicos/metabolismo , Venenos Elapídicos/toxicidade , Elapidae/metabolismo , Lagartos/metabolismo , Ophiophagus hannah/metabolismo , Ratos , Receptores Nicotínicos/metabolismo , Venenos de Serpentes/química , Toxinas Biológicas/metabolismo
11.
Parasitology ; 149(11): 1468-1478, 2022 09.
Artigo em Inglês | MEDLINE | ID: mdl-35920304

RESUMO

The combined use of molecular and microscopic techniques has become an increasingly common and efficient practice for the taxonomic and evolutionary understanding of single-celled parasites such as haemogregarines. Based on this integrative approach, we characterized Hepatozoon found in Helicops angulatus snakes from the Eastern Amazonia, Brazil. The gamonts observed caused cell hypertrophy and were extremely elongated and, in some cases, piriform (mean dimensions: 25.3 ± 1.9 × 8.6 ± 1.3 µm). These morphological features correspond to Hepatozoon carinicauda, described 50 years ago in the snake Helicops carinicaudus in the southeast region of Brazil. Phylogenetic and genetic divergence analyses, performed with the sequence obtained from the amplification of a 590 bp fragment of the 18S rRNA gene, revealed that Hepatozoon in He. angulatus differed from the other lineages retrieved from GenBank, and was clustered singly in both the phylogenetic tree and the haplotype network. The integration of these data allowed the identification of H. carinicauda in a new aquatic host, and increased the knowledge of its geographical distribution. Therefore, the present study included the first redescription of a Hepatozoon species in a snake from the Brazilian Amazon.


Assuntos
Coccidiose , Colubridae , Eucoccidiida , Animais , Brasil , Coccidiose/parasitologia , Coccidiose/veterinária , Colubridae/parasitologia , Eucoccidiida/genética , Masculino , Filogenia , RNA Ribossômico 18S/genética
12.
Toxins (Basel) ; 14(7)2022 07 15.
Artigo em Inglês | MEDLINE | ID: mdl-35878227

RESUMO

Many venomous animals express toxins that show extraordinary levels of variation both within and among species. In snakes, most studies of venom variation focus on front-fanged species in the families Viperidae and Elapidae, even though rear-fanged snakes in other families vary along the same ecological axes important to venom evolution. Here we characterized venom gland transcriptomes from 19 snakes across two dipsadine rear-fanged genera (Leptodeira and Helicops, Colubridae) and two front-fanged genera (Bothrops, Viperidae; Micrurus, Elapidae). We compared patterns of composition, variation, and diversity in venom transcripts within and among all four genera. Venom gland transcriptomes of rear-fanged Helicops and Leptodeira and front-fanged Micrurus are each dominated by expression of single toxin families (C-type lectins, snake venom metalloproteinase, and phospholipase A2, respectively), unlike highly diverse front-fanged Bothrops venoms. In addition, expression patterns of congeners are much more similar to each other than they are to species from other genera. These results illustrate the repeatability of simple venom profiles in rear-fanged snakes and the potential for relatively constrained venom composition within genera.


Assuntos
Colubridae , Toxinas Biológicas , Viperidae , Animais , Colubridae/genética , Colubridae/metabolismo , Metaloproteases/genética , Metaloproteases/metabolismo , Venenos de Serpentes/genética , Venenos de Serpentes/metabolismo , Toxinas Biológicas/metabolismo , Transcriptoma , Viperidae/metabolismo
13.
Sci Rep ; 12(1): 12303, 2022 07 19.
Artigo em Inglês | MEDLINE | ID: mdl-35853982

RESUMO

The ascomycete fungus Ophidiomyces ophiodiicola (Oo) is the causative agent of ophidiomycosis (Snake Fungal Disease), which has been detected globally. However, surveillance efforts in the central U.S., specifically Texas, have been minimal. The threatened and rare Brazos water snake (Nerodia harteri harteri) is one of the most range restricted snakes in the U.S. and is sympatric with two wide-ranging congeners, Nerodia erythrogaster transversa and Nerodia rhombifer, in north central Texas; thus, providing an opportunity to test comparative host-pathogen associations in this system. To accomplish this, we surveyed a portion of the Brazos river drainage (~ 400 river km) over 29 months and tested 150 Nerodia individuals for the presence of Oo via quantitative PCR and recorded any potential signs of Oo infection. We found Oo was distributed across the entire range of N. h. harteri, Oo prevalence was 46% overall, and there was a significant association between Oo occurrence and signs of infection in our sample. Models indicated adults had a higher probability of Oo infection than juveniles and subadults, and adult N. h. harteri had a higher probability of infection than adult N. rhombifer but not higher than adult N. e. transversa. High Oo prevalence estimates (94.4%) in adult N. h. harteri has implications for their conservation and management owing to their patchy distribution, comparatively low genetic diversity, and threats from anthropogenic habitat modification.


Assuntos
Colubridae , Dermatomicoses , Onygenales , Animais , Dermatomicoses/microbiologia , Humanos , Serpentes/microbiologia , Simpatria
14.
Sci Rep ; 12(1): 12705, 2022 07 26.
Artigo em Inglês | MEDLINE | ID: mdl-35882893

RESUMO

Animal movements reflect temporal and spatial availability of resources as well as when, where, and how individuals access such resources. To test these relationships for a predatory reptile, we quantified the effects of prey abundance on the spatial ecology of invasive brown treesnakes (Boiga irregularis) on Guam. Five months after toxicant-mediated suppression of a brown treesnake population, we simultaneously used visual encounter surveys to generate relative rodent abundance and radiotelemetry of snakes to document movements of surviving snakes. After snake suppression, encounter rates for small mammals increased 22-fold and brown treesnakes had smaller mean daily movement distances (24 ± 13 m/day, [Formula: see text] ± SD) and activity areas (5.47 ± 5 ha) than all previous observations. Additionally, snakes frequenting forest edges, where our small mammal encounters were the highest, had smaller mean daily movement distances and three-dimensional activity volumes compared to those within the forest interior. Collectively, these results suggest that reduced movements by snakes were in part a response to increased prey availability. The impact of prey availability on snake movement may be a management consideration when attempting to control cryptic invasive species using tools that rely on movement of the target species to be effective.


Assuntos
Colubridae , Animais , Colubridae/fisiologia , Guam , Espécies Introduzidas , Mamíferos , Comportamento Predatório , Serpentes/fisiologia
15.
Parasitology ; 149(11): 1419-1424, 2022 09.
Artigo em Inglês | MEDLINE | ID: mdl-35801291

RESUMO

Invasive species pose a threat not only to biodiversity because they displace or compete with native fauna, but also because of the pathogens they can host. The Canary Islands are an Atlantic biodiversity hotspot threatened by increasing numbers of invasive species, including the California kingsnake Lampropeltis californiae, which was recently introduced to Gran Canaria. Seventy-seven snakes were examined for gastrointestinal parasites in 2019­2020. Sporocysts of Sarcocystis sp. were detected in 10 of them; detection of gamogonia stages in histological sections of 3 snakes confirmed the snake as a definitive host. Partial ssrDNA was amplified using SarcoFext/SarcoRext primers; an additional sequence of Sarcocystis was obtained from the tail muscle of the endemic Gran Canaria giant lizard Gallotia stehlini for a comparison. Identical ssrDNA sequences of unknown Sarcocystis sp. were obtained from 5 different snakes. Phylogenetic analysis showed that Sarcocystis sp. isolated from invasive California kingsnakes is unrelated to Sarcocystis provisionally considered S. stehlini from the endemic lizard. The dixenous coccidia are rarely reported to invade new predator­prey systems. However, the present data suggest that previously unknown Sarcocystis sp. is circulating among invasive snakes and as yet unknown vertebrate intermediate hosts, with undetermined consequences for the Gran Canaria ecosystem.


Assuntos
Apicomplexa , Colubridae , Lagartos , Sarcocystidae , Sarcocystis , Sarcocistose , Animais , Colubridae/parasitologia , Ecossistema , Lagartos/parasitologia , Filogenia , Sarcocistose/epidemiologia , Espanha/epidemiologia
16.
J Zoo Wildl Med ; 53(2): 266-274, 2022 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-35758568

RESUMO

Environmental enrichment is a strategy used to improve the welfare of animals under human care. While enrichment techniques for mammals and birds have been studied extensively, reptilian enrichment has received less attention. There has been an increase in enrichment programs for reptiles in zoological institutions, however many are not accompanied by behavioral studies. Detailed recording of behavioral responses to enrichment is necessary to assess the efficacy of the enrichment type and to determine its utility in various settings. In this study, 18 snakes of multiple species, from two Families (Colubridae, Pythonidae), were exposed to four enrichment types (Humid Hide, Olfactory, Climbing, Suspended Hide). Baseline recordings were conducted prior to the introduction of enrichment. Snakes were recorded for two hours after introduction of each item. Five behavior types were identified based on baseline videos: tongue flicking, climbing, hiding, interacting with transparent boundaries, and utilizing non-enrichment items. Interacting with transparent boundaries was classified as an undesirable behavior, while the other four behaviors were classified as desirable. Changes in climbing and tongue flicking behaviors were noted with introduction of each item- these changes were not statistically significant. The increase in these behaviors may indicate clinical importance, and shows that snakes under human care respond to environmental enrichment. As some snakes showed a reduction in undesirable behaviors when compared to baseline conditions, this may suggest increased welfare during times when enrichment is offered. The extent to which these results can be applied to other species merits further study.


Assuntos
Colubridae , Animais , Comportamento Animal , Aves , Colubridae/fisiologia , Mamíferos , Répteis
17.
Integr Comp Biol ; 62(4): 852-864, 2022 10 29.
Artigo em Inglês | MEDLINE | ID: mdl-35657730

RESUMO

As organisms transition between different environments, they must do more than simply move through that transition and those environments. Changes in the environment must be detected via the senses. The types of sensory information and the mechanisms of collecting that information may also change as an individual moves through different environments. We use tongue-flicking in northern water snakes, Nerodia sipedon, to examine the mechanics of sensory behavior as snakes move from terrestrial to aquatic habitats. A combination of high-speed video and mesocosm experiment revealed that water snakes will alter the mechanics of tongue-flicking in the context of their environment. Tongue-flicks on land are distinctive, with multiple oscillations, large protrusion distance, and high velocities. Comparatively, tongue-flicks under water are much shorter events, with reduced protrusion and fewer oscillations. At the surface of the water, in the presence of potential anuran prey, water snakes will tap the tips of the tongue on the surface of the water, without undergoing the full oscillations observed on land or underwater. We attribute the differences in the aerial and underwater tongue-flicks to trade-offs in the physical and chemical properties of the environment. The surface tapping behavior we observed is likely snakes altering their behavior to maximize the encounter and collection of frog-specific chemical cues, which are known to travel on the water's surface. Given the ecological transitions and distinctive biogeographical patterns rooted in water snake ecology, there are likely more examples of changing sensory mechanics to be discovered upon further investigation.


Assuntos
Colubridae , Animais , Fenômenos Biomecânicos , Água , Língua , Ecossistema
18.
J Exp Zool B Mol Dev Evol ; 338(6): 331-341, 2022 09.
Artigo em Inglês | MEDLINE | ID: mdl-35652464

RESUMO

The chorioallantoic membrane of oviparous reptiles forms a vascular interface with the eggshell. The eggshell contains calcium, primarily as calcium carbonate. Extraction and mobilization of this calcium by the chorioallantoic membrane contributes importantly to embryonic nutrition. Development of the chorioallantoic membrane is primarily known from studies of squamates and birds. Although there are pronounced differences in eggshell structure, squamate and bird embryos each mobilize calcium from eggshells. Specialized cells in the chicken chorionic epithelium transport calcium from the eggshell aided by a second population of cells that secrete protons generated by the enzyme carbonic anhydrase. Calcium transporting cells also are present in the chorioallantoic membrane of corn snakes, although these cells function differently than those of chickens. We used histology and immunohistology to characterize the morphology and functional attributes of the chorioallantoic membrane of corn snakes. We identified two populations of cells in the outer layer of the chorionic epithelium. Calbindin-D28K , a cellular marker for calcium transport expressed in squamate chorioallantoic membranes, is localized in large, flattened cells that predominate in the chorionic epithelium. Smaller cells, interspersed among the large cells, express carbonic anhydrase 2, an enzyme not previously localized in the chorionic epithelium of an oviparous squamate. These findings indicate that differentiation of chorionic epithelial cells contributes to extraction and transport of calcium from the eggshell. The presence of specializations of chorioallantoic membranes for calcium uptake from eggshells in chickens and corn snakes suggests that eggshell calcium was a source of embryonic nutrition early in the evolution of Sauropsida.


Assuntos
Anidrases Carbônicas , Colubridae , Animais , Cálcio/metabolismo , Anidrases Carbônicas/metabolismo , Galinhas , Membrana Corioalantoide , Casca de Ovo , Oviparidade
19.
Toxins (Basel) ; 14(5)2022 05 02.
Artigo em Inglês | MEDLINE | ID: mdl-35622569

RESUMO

Yamakagashi (Rhabdophis tigrinus) inhabits Japan widely, and incidents involving its bites occur every year. Its bite causes disseminated intravascular coagulation when the amount of infused venom is high, and it can be fatal if treatment with Yamakagashi antivenom is delayed. Although Yamakagashi antivenom is used for treating Yamakagashi bites, it is an unapproved drug and its capacity for storage is limited. Hence, it is difficult to administer to patients promptly. As a therapeutic agent for this bite, we investigated the application of recombinant thrombomodulin alpha, a commercially available disseminated intravascular coagulation therapeutic agent. Its therapeutic effect on Yamakagashi venom was confirmed in a coagulation system of human plasma using in vitro Yamakagashi venom as well as a rat experimental model of disseminated intravascular coagulation using in vivo Yamakagashi venom. The administration of recombinant thrombomodulin alpha induced an effect that prolonged the blood coagulation time of Yamakagashi venom in vitro, and the drug was administered in vivo within 0.5 h after the administration of Yamakagashi venom to save rats. Blood coagulation markers such as platelet count, prothrombin time, fibrinogen concentration, and D-dimer levels recovered to normal values in rats. Therefore, recombinant thrombomodulin alpha may be used as a therapeutic agent for Yamakagashi bites.


Assuntos
Colubridae , Coagulação Intravascular Disseminada , Animais , Anticoagulantes/uso terapêutico , Antivenenos/uso terapêutico , Humanos , Ratos , Trombomodulina/uso terapêutico , Peçonhas/uso terapêutico
20.
Artigo em Inglês | MEDLINE | ID: mdl-35490925

RESUMO

The Green racer Philodryas patagoniensis is a snake species from South America and accidents with this genus are often neglected. Therefore, this study aimed to evaluate the toxicological, cytotoxic, and inflammatory potential of P. patagoniensis venom (PpV). The experimental model Artemia salina was used to determine toxicity through the median lethal dose (LD50). Cell viability and genotoxicity were evaluated in human mononuclear cells using the Trypan blue test and the Comet assay, respectively. To assess inflammation, mice had the ventral surface of the right hind paw injected with saline, formalin, and three different concentrations of venom (1, 1.5, and 2 µg. 50 µL-1). LD50 in A. salina was 461 µg. mL-1. PpV caused a significant increase in cell death and genotoxicity in human mononuclear cells at two concentrations (575 and 1150 µg. mL-1). PpV shown also to be a strong agent causing nociception in mice. Paw edema totaled four days at 1.5 µg. 50 µL-1. The hyperalgesia caused by the venom had a long duration in mice, lasting eight days at all concentrations evaluated. Thus, we evaluated for the first time the toxicological potential of PpV in A. salina model and in leukocytes. We concluded that systemic oxidative stress, which we infer to be in the genesis of cytotoxicity and genotoxicity observed in vitro, and the inflammatory process are part of the pathways that trigger the venom damage cascades. Relevant data for both scientific research and clinical medicine. Nonetheless, studies are needed to elucidate these mechanisms.


Assuntos
Colubridae , Venenos de Serpentes , Animais , Colubridae/metabolismo , Edema/induzido quimicamente , Inflamação/induzido quimicamente , Leucócitos/metabolismo , Camundongos , Venenos de Serpentes/metabolismo
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