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2.
BMC Evol Biol ; 19(1): 174, 2019 08 28.
Artigo em Inglês | MEDLINE | ID: mdl-31462236

RESUMO

BACKGROUND: A number of non-visual responses to light in vertebrates, such as circadian rhythm control and pupillary light reflex, are mediated by melanopsins, G-protein coupled membrane receptors, conjugated to a retinal chromophore. In non-mammalian vertebrates, melanopsin expression is variable within the retina and extra-ocular tissues. Two paralog melanopsin genes were classified in vertebrates, Opn4x and Opn4m. Snakes are highly diversified vertebrates with a wide range of daily activity patterns, which raises questions about differences in structure, function and expression pattern of their melanopsin genes. In this study, we analyzed the melanopsin genes expressed in the retinas of 18 snake species from three families (Viperidae, Elapidae, and Colubridae), and also investigated extra-retinal tissue expression. RESULTS: Phylogenetic analysis revealed that the amplified gene belongs to the Opn4x group, and no expression of the Opn4m was found. The same paralog is expressed in the iris, but no extra-ocular expression was detected. Molecular evolutionary analysis indicated that melanopsins are evolving primarily under strong purifying selection, although lower evolutionary constraint was detected in snake lineages (ω = 0.2), compared to non-snake Opn4x and Opn4m (ω = 0.1). Statistical analysis of selective constraint suggests that snake phylogenetic relationships have driven stronger effects on melanopsin evolution, than the species activity pattern. In situ hybridization revealed the presence of melanopsin within cells in the outer and inner nuclear layers, in the ganglion cell layer, and intense labeling in the optic nerve. CONCLUSIONS: The loss of the Opn4m gene and extra-ocular photosensitive tissues in snakes may be associated with a prolonged nocturnal/mesopic bottleneck in the early history of snake evolution. The presence of melanopsin-containing cells in all retinal nuclear layers indicates a globally photosensitive retina, and the expression in classic photoreceptor cells suggest a regionalized co-expression of melanopsin and visual opsins.


Assuntos
Proteínas de Répteis/genética , Retina/metabolismo , Opsinas de Bastonetes/genética , Serpentes/genética , Animais , Relógios Circadianos , Evolução Molecular , Regulação da Expressão Gênica , Filogenia , Opsinas de Bastonetes/fisiologia , Serpentes/classificação , Serpentes/fisiologia , Visão Ocular
3.
PLoS One ; 14(7): e0218851, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31314800

RESUMO

The Western Ghats are well known as a biodiversity hotspot, but the full extent of its snake diversity is yet to be uncovered. Here, we describe a new genus and species of vine snake Proahaetulla antiqua gen. et sp. nov., from the Agasthyamalai hills in the southern Western Ghats. It was found to be a member of the Ahaetuliinae clade, which currently comprises the arboreal snake genera Ahaetulla, Dryophiops, Dendrelaphis and Chrysopelea, distributed in South and Southeast Asia. Proahaetulla shows a sister relationship with all currently known taxa belonging to the genus Ahaetulla, and shares ancestry with Dryophiops. In addition to its phylogenetic position and significant genetic divergence, this new taxon is also different in morphology from members of Ahaetuliinae in a combination of characters, having 12-13 partially serrated keels on the dorsal scale rows, 20 maxillary teeth and 3 postocular scales. Divergence dating reveals that the new genus is ancient, dating back to the Mid-Oligocene, and is one of the oldest persisting monotypic lineages of snakes in the Western Ghats. This discovery adds to the growing list of ancient lineages endemic to the Agasthyamalai hills and underscores the biogeographic significance of this isolated massif in the southern Western Ghats.


Assuntos
Biodiversidade , Colubridae/fisiologia , Filogenia , Serpentes/fisiologia , Animais , Colubridae/classificação , Colubridae/genética , Arco Dental/fisiologia , Deriva Genética , Especiação Genética , Índia , Serpentes/classificação , Serpentes/genética
4.
Rev Soc Bras Med Trop ; 52: e20190120, 2019 May 30.
Artigo em Inglês | MEDLINE | ID: mdl-31166491

RESUMO

INTRODUCTION: In this study, we examined the clinical manifestations, laboratory evidence, and the circumstances of snakebites caused by non-venomous snakes, which were treated at the Regional Hospital of Juruá in Cruzeiro do Sul. METHODS: Data were collected through patient interviews, identification of the species that were taken to the hospital, and the clinical manifestations. RESULTS: Eight confirmed and four probable cases of non-venomous snakebites were recorded. CONCLUSIONS: The symptoms produced by the snakes Helicops angulatus and Philodryas viridissima, combined with their coloration can be confused with venomous snakes (Bothrops atrox and Bothrops bilineatus), thus resulting in incorrect bothropic snakebite diagnosis.


Assuntos
Mordeduras de Serpentes/diagnóstico , Serpentes/anatomia & histologia , Animais , Brasil/epidemiologia , Colubridae , Erros de Diagnóstico , Feminino , Humanos , Masculino , Mordeduras de Serpentes/epidemiologia , Serpentes/classificação , Serpentes/fisiologia
5.
Naturwissenschaften ; 106(5-6): 24, 2019 May 08.
Artigo em Inglês | MEDLINE | ID: mdl-31069520

RESUMO

Acclimation to lower temperatures decreases energy expenditure in ectotherms but increases oxygen consumption in most endotherms, when dropped below thermoneutrality. Such differences should be met by adjustments in oxygen transport through blood. Changes in hematological variables in correspondence to that in metabolic rates are, however, not fully understood, particularly in non-avian reptiles. We investigated the effect of thermal acclimation on a snake model, the grass snakes (Natrix natrix). After 6 months of acclimation to either 18 °C or 32 °C hematocrit, hemoglobin concentration, erythrocyte number, and size were assessed. All variables revealed significantly lower values under warm compared to cold ambient temperature. Our data suggest that non-avian reptiles, similarly as birds, reduce erythrocyte fraction under energy-demanding temperatures. Due to low deformability of nucleated erythrocytes in sauropsids, such reduced fraction may be important in decreasing blood viscosity to optimize blood flow. Novel findings on flexible erythrocyte size provide an important contribution to this optimization process.


Assuntos
Aclimatação/fisiologia , Temperatura Baixa , Eritrócitos/fisiologia , Serpentes/fisiologia , Animais , Tamanho Celular , Contagem de Eritrócitos , Hematócrito , Hemoglobinas , Temperatura Alta
6.
Proc Natl Acad Sci U S A ; 116(11): 4798-4803, 2019 03 12.
Artigo em Inglês | MEDLINE | ID: mdl-30804193

RESUMO

Limbless animals like snakes inhabit most terrestrial environments, generating thrust to overcome drag on the elongate body via contacts with heterogeneities. The complex body postures of some snakes and the unknown physics of most terrestrial materials frustrates understanding of strategies for effective locomotion. As a result, little is known about how limbless animals contend with unplanned obstacle contacts. We studied a desert snake, Chionactis occipitalis, which uses a stereotyped head-to-tail traveling wave to move quickly on homogeneous sand. In laboratory experiments, we challenged snakes to move across a uniform substrate and through a regular array of force-sensitive posts. The snakes were reoriented by the array in a manner reminiscent of the matter-wave diffraction of subatomic particles. Force patterns indicated the animals did not change their self-deformation pattern to avoid or grab the posts. A model using open-loop control incorporating previously described snake muscle activation patterns and body-buckling dynamics reproduced the observed patterns, suggesting a similar control strategy may be used by the animals. Our results reveal how passive dynamics can benefit limbless locomotors by allowing robust transit in heterogeneous environments with minimal sensing.


Assuntos
Locomoção , Serpentes/fisiologia , Animais , Fenômenos Biomecânicos , Modelos Biológicos
7.
Bioinspir Biomim ; 14(3): 036005, 2019 02 26.
Artigo em Inglês | MEDLINE | ID: mdl-30699386

RESUMO

Transient locomotion under water is highly constrained by drag and added mass, yet some aquatic snakes catch their prey using a fast forward acceleration, with the mouth opened. These aquatic snakes show a convergence of their head shape in comparison with closely related species that do not forage under water. As both drag and added mass are related to some extent to the shape of the moving object, we explored how shape impacts the hydrodynamic forces applied to the head of a snake during a prey capture event. We compared two 3D-printed heads representing typical shapes of aquatically-foraging and non-aquatically-foraging snakes, and frontal strike kinematics based on in vivo observations. By using direct force measurements, we calculated the drag and added mass coefficient of the two models. Our results show that both drag and added mass are reduced in aquatic snakes. The drag coefficient of the aquatic model is 0.24, which is almost two times smaller than the non-aquatic model. The added mass coefficient of the aquatic model is 0.15 versus 0.24 for the non-aquatic model, showing that the convergence of head shape in aquatically foraging snakes is associated with a hydrodynamic advantage during frontal striking. The vorticity field measurements with particle image velocimetry show that a less intense recirculation bubble behind the jaw of the aquatic model, compared to the non-aquatic model, might be the basis of this advantage.


Assuntos
Hidrodinâmica , Modelos Biológicos , Comportamento Predatório/fisiologia , Serpentes/fisiologia , Natação/fisiologia , Animais , Fenômenos Biomecânicos
8.
An Acad Bras Cienc ; 91(suppl 1): e20170976, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-29791565

RESUMO

Body-size is significantly correlated with the number of vertebrae (pleomerism) in multiple vertebrate lineages, indicating that somitogenesis process is an important factor dictating evolutionary change associated to phyletic allometry and, consequently, species fitness and diversification. However, the role of the evolution of extreme body sizes (dwarfism and gigantism) remains elusive in snakes, mainly with respect to postnatal ontogeny in dietary preferences associated with evolution of gigantism in many lineages. We described herein a new species in the highly diversified and species-rich genus Atractus on the basis of four specimens from the southeastern slopes of the Ecuadorian Andes. The new species is morphologically similar and apparently closely related to two other allopatric giant congeners (A. gigas and A. touzeti), from which it can be distinguished by their distinct dorsal and ventral coloration, the number of supralabial and infralabial scales, the number of maxillary teeth, and relative width of the head. In addition, we discuss on the ontogenetic trajectories hypotheses and dietary specializations related to evolution of gigantism in the goo-eaters genus Atractus.


Assuntos
Tamanho Corporal , Comportamento Alimentar/fisiologia , Serpentes/anatomia & histologia , Animais , Evolução Biológica , Equador , Feminino , Serpentes/classificação , Serpentes/fisiologia
9.
Artigo em Inglês | MEDLINE | ID: mdl-30268769

RESUMO

While it has been known for a while that some snake species are extremely sensitive to acetaminophen, the underlying mechanism for this toxicity has not been reported. To investigate if essential detoxification enzymes are missing in snake species that are responsible for biotransformation of acetaminophen in other vertebrate species, livers were collected from a variety of snake species, together with samples from alligator, snapping turtle, cat, rat, and cattle. Subcellular fractions were analyzed for enzymatic activities of phenol-type sulfotransferase and UDP­glucuronosyltransferase, total glutathione S­transferase, and N­acetyltransferase. The results showed that none of the snake species, together with the cat samples, had any phenol-type glucuronidation activity, and that this activity was much lower in alligator and turtle samples than in the mammalian species. Combined with the lack of N­acetyltransferase activity in snakes and cats, this would explain the accumulation of the aminophenol metabolite, which induces methemoglobinemia and subsequent suffocation of snakes and cats after acetaminophen exposure. While previous investigations have concluded that in cats the gene for the phenol-type glucuronosyltransferase isoform has turned into a pseudogene because of several point mutations, evaluation of genomic information for snake species revealed that they have only 2 genes that may code for glucuronosyltransferase isoforms. Similarity of these genes with mammalian genes is <50%, and suggests that the expressed enzymes may act on other types of substrates than aromatic amines. This indicates that the extreme sensitivity for acetaminophen in snakes is based on a different phylogenetic origin than the sensitivity observed in cats.


Assuntos
Acetaminofen/metabolismo , Poluentes Ambientais/metabolismo , Fígado/enzimologia , Filogenia , Proteínas de Répteis/metabolismo , Serpentes/fisiologia , Acetaminofen/efeitos adversos , Acetaminofen/toxicidade , Acetiltransferases/genética , Acetiltransferases/metabolismo , Agkistrodon/genética , Agkistrodon/fisiologia , Analgésicos não Entorpecentes/efeitos adversos , Analgésicos não Entorpecentes/metabolismo , Animais , Biotransformação , Boidae/genética , Boidae/fisiologia , Colubridae/genética , Colubridae/fisiologia , Crotalus/genética , Crotalus/fisiologia , Bases de Dados Genéticas , Resistência a Medicamentos , Poluentes Ambientais/toxicidade , Glucuronosiltransferase/genética , Glucuronosiltransferase/metabolismo , Glutationa Transferase/genética , Glutationa Transferase/metabolismo , Isoenzimas/genética , Isoenzimas/metabolismo , Proteínas de Répteis/genética , Serpentes/genética , Especificidade da Espécie , Sulfotransferases/genética , Sulfotransferases/metabolismo , Toxicocinética
10.
PLoS Negl Trop Dis ; 12(12): e0007014, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-30507945

RESUMO

Taiwan is an island located in the south Pacific, a subtropical region that is home to 61 species of snakes. Of these snakes, four species-Trimeresurus stejnegeri, Protobothrops mucrosquamatus, Bungarus multicinctus and Naja atra-account for more than 90% of clinical envenomation cases. Currently, there are two types of bivalent antivenom: hemorrhagic antivenom against the venom of T. stejnegeri and P. mucrosquamatus, and neurotoxic antivenom for treatment of envenomation by B. multicinctus and N. atra. However, no suitable detection kits are available to precisely guide physicians in the use of antivenoms. Here, we sought to develop diagnostic assays for improving the clinical management of snakebite in Taiwan. A two-step affinity purification procedure was used to generate neurotoxic species-specific antibodies (NSS-Abs) and hemorrhagic species-specific antibodies (HSS-Abs) from antivenoms. These two SSAbs were then used to develop a sandwich ELISA (enzyme-linked immunosorbent assay) and a lateral flow assay comprising two test lines. The resulting ELISAs and lateral flow strip assays could successfully discriminate between neurotoxic and hemorrhagic venoms. The limits of quantification (LOQ) of the ELISA for neurotoxic venoms and hemorrhagic venoms were determined to be 0.39 and 0.78 ng/ml, respectively, and the lateral flow strips were capable of detecting neurotoxic and hemorrhagic venoms at concentrations lower than 5 and 50 ng/ml, respectively, in 10-15 min. Tests of lateral flow strips in 21 clinical snakebite cases showed 100% specificity and 100% sensitivity for neurotoxic envenomation, whereas the sensitivity for detecting hemorrhagic envenomation samples was 36.4%. We herein presented a feasible strategy for developing a sensitive sandwich ELISA and lateral flow strip assay for detecting and differentiating venom proteins from hemorrhagic and neurotoxic snakes. A useful snakebite diagnostic guideline according to the lateral flow strip results and clinical symptoms was proposed to help physicians to use antivenoms appropriately. The two-test-line lateral flow strip assay could potentially be applied in an emergency room setting to help physicians diagnose and manage snakebite victims.


Assuntos
Ensaio de Imunoadsorção Enzimática/métodos , Mordeduras de Serpentes/diagnóstico , Serpentes/fisiologia , Animais , Antivenenos/imunologia , Reações Cruzadas , Ensaio de Imunoadsorção Enzimática/instrumentação , Feminino , Humanos , Camundongos Endogâmicos C57BL , Mordeduras de Serpentes/sangue , Mordeduras de Serpentes/parasitologia , Serpentes/classificação , Serpentes/imunologia , Taiwan
11.
J Therm Biol ; 78: 36-41, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30509659

RESUMO

Reactive oxygen species (ROS) are inescapable byproducts of energy metabolism and may cause costly damage to biomolecules. Organisms have evolved different means to counter oxidative stress, such as modulation of ROS production, neutralization of produced ROS through free radical scavenging and the repair or removal of the damaged structures. A positive relationship between metabolic rate and ROS production is commonly expected, but the oxidative burden of aerobic metabolism remains poorly understood. We investigated whether acclimation to ambient temperatures imposing variation in standard metabolic rate (SMR) is mirrored in the oxidative status of an ectotherm. Grass snakes (Natrix natrix) acclimated for six months to warm (32 °C) conditions revealed seven times higher SMR compared to cold-acclimated (18 °C) individuals. In contrast to SMR, the amount of damage measured as reactive oxygen metabolites test (dROMs) and abundance of micronucleated erythrocytes was significantly lower in warm-acclimated individuals, while non-enzymatic antioxidant capacity of plasma was unaltered by thermal acclimation. Our results support that high SMR may allow snakes to better cope with oxidative stress, possibly through tissue repair or removal of damaged tissues that also requires energy costs. The reversed association between self-maintenance metabolism and oxidative damage to biomolecules provides novel rational for temperature dependent life histories of ectotherms. How oxidative stress may contribute to the known reduced rates of ectotherm growth or reproduction under cold temperatures or if oxidative stress may even drive such life history trait declines are now important challenges to be addressed.


Assuntos
Aclimatação , Metabolismo Energético , Estresse Oxidativo , Serpentes/fisiologia , Animais , Temperatura Corporal , Serpentes/metabolismo
12.
Zoolog Sci ; 35(4): 330-352, 2018 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-30079836

RESUMO

Few convenient/expeditious methods for identifying the species of shed snake skins in specific areas have been developed. The scales on shed snake skins are permeable to light and can be examined by light microscopy (LM), which is of higher availability-especially for wild animal researchers and citizen scientists-than conventional approach which examines the scale microstructures by scanning electron microscopy. We collected and examined a total of 801 shed samples or scale specimens from 53 snake species in Taiwan and adjacent islands, and developed the first guide to identify the fragmented or faded shed skins of most snake species by LM. Morphological characters of scales can be examined by LM include the apical notch, apical pits, apical lobes, keels, scale symmetry, unpigmented spots (mechanoreceptor-like organs), interscale follicles, cross/longitudinal micro-ridge, oberhautchen cells, rows of spines, light/tiny dots, and other microstructures. The microstructures on the scale specimens prepared by the stripped method and the impression method were similar to those on shed skins when examined by LM. We investigated the variations of scale morphology associated with ontogeny, body region, and position on scales, discussed the character evolution of snake scale morphology, and certified that the interscale follicles and the unpigmented spots could also be useful characters for shed skin identification. The methods and results of this study could be applied to identify squamate skins/sloughs and even fecal remnants.


Assuntos
Muda/fisiologia , Pele , Serpentes/classificação , Serpentes/fisiologia , Escamas de Animais/fisiologia , Animais , Pigmentos Biológicos , Especificidade da Espécie
13.
Proc Natl Acad Sci U S A ; 115(33): 8406-8411, 2018 08 14.
Artigo em Inglês | MEDLINE | ID: mdl-30065117

RESUMO

Several previous genomic studies have focused on adaptation to high elevations, but these investigations have been largely limited to endotherms. Snakes of the genus Thermophis are endemic to the Tibetan plateau and therefore present an opportunity to study high-elevation adaptations in ectotherms. Here, we report the de novo assembly of the genome of a Tibetan hot-spring snake (Thermophis baileyi) and then compare its genome to the genomes of the other two species of Thermophis, as well as to the genomes of two related species of snakes that occur at lower elevations. We identify 308 putative genes that appear to be under positive selection in Thermophis We also identified genes with shared amino acid replacements in the high-elevation hot-spring snakes compared with snakes and lizards that live at low elevations, including the genes for proteins involved in DNA damage repair (FEN1) and response to hypoxia (EPAS1). Functional assays of the FEN1 alleles reveal that the Thermophis allele is more stable under UV radiation than is the ancestral allele found in low-elevation lizards and snakes. Functional assays of EPAS1 alleles suggest that the Thermophis protein has lower transactivation activity than the low-elevation forms. Our analysis identifies some convergent genetic mechanisms in high-elevation adaptation between endotherms (based on studies of mammals) and ectotherms (based on our studies of Thermophis).


Assuntos
Aclimatação/fisiologia , Altitude , Serpentes/genética , Alelos , Animais , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Evolução Molecular , Feminino , Endonucleases Flap/genética , Genoma , Hipóxia , Filogenia , Seleção Genética , Serpentes/fisiologia , Tibet , Raios Ultravioleta
15.
PLoS Negl Trop Dis ; 12(7): e0006643, 2018 07.
Artigo em Inglês | MEDLINE | ID: mdl-29985919

RESUMO

INTRODUCTION: The global incidence of snakebite is estimated at more than 2.5 million cases annually, with greater than 100,000 deaths. Historically, Myanmar has one of the highest incidences of venomous snakebites. In order to improve the health outcomes of snakebite patients in Myanmar, access to accurate snakebite incidence data is crucial. The last population-based study in Myanmar was conducted more than a decade ago. In 2014, the Ministry of Health and Sports data from health facilities indicated an incidence of about 29.5 bites/ 100,000 population/year (a total of 15,079 bites). Since data from health facilities lack information about those who do not seek health care from government health services, a new population-based survey was conducted in 2 rural areas of Mandalay region. The survey data were compared to those obtained from healthcare services. METHOD: 4,276 rural respondents in Kyaukse and Madaya townships in Mandalay Division were recruited using cluster sampling that involved random selection of 150 villages and random sampling of 30 households from each village. One adult member of each household was interviewed using a structured questionnaire. RESULTS: One respondent from each of 4,276 households represented 19,877 residents from 144 villages. 24 people in these households had suffered snakebite during the last one year giving an annual incidence of 116/100,000. During the last ten years, 252 people suffered snakebites. 44.1% of the victims were women. 14% of the villages reported 4 or more bites during the last ten years, whereas 27% villages reported no snakebites. 92.4% of the victims recovered fully, 5.4% died, and 2% suffered long term health issues. One victim was reported to have died from causes unrelated to the snakebite. While there was no statistically significant difference between outcomes for children and adults, 4 of 38 of those under 18 years of age died compared to 7 of 133 adults between 19 to 40 years of age. CONCLUSION: This incidence reported by the community members points to substantially more snakebites than the number of snakebite patients attending health facilities. This higher incidence points to the need for a nation-wide population-based survey, community education about gaining access to care where antivenom is available, and to the potential need for a larger supply of antivenom and expansion of medical care in rural areas.


Assuntos
Mordeduras de Serpentes/epidemiologia , Adolescente , Adulto , Animais , Antivenenos/administração & dosagem , Criança , Feminino , Humanos , Incidência , Masculino , Mianmar/epidemiologia , População Rural/estatística & dados numéricos , Mordeduras de Serpentes/tratamento farmacológico , Mordeduras de Serpentes/parasitologia , Serpentes/fisiologia , Adulto Jovem
16.
Genome Biol Evol ; 10(8): 2110-2129, 2018 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-30060036

RESUMO

Colubridae represents the most phenotypically diverse and speciose family of snakes, yet no well-assembled and annotated genome exists for this lineage. Here, we report and analyze the genome of the garter snake, Thamnophis sirtalis, a colubrid snake that is an important model species for research in evolutionary biology, physiology, genomics, behavior, and the evolution of toxin resistance. Using the garter snake genome, we show how snakes have evolved numerous adaptations for sensing and securing prey, and identify features of snake genome structure that provide insight into the evolution of amniote genomes. Analyses of the garter snake and other squamate reptile genomes highlight shifts in repeat element abundance and expansion within snakes, uncover evidence of genes under positive selection, and provide revised neutral substitution rate estimates for squamates. Our identification of Z and W sex chromosome-specific scaffolds provides evidence for multiple origins of sex chromosome systems in snakes and demonstrates the value of this genome for studying sex chromosome evolution. Analysis of gene duplication and loss in visual and olfactory gene families supports a dim-light ancestral condition in snakes and indicates that olfactory receptor repertoires underwent an expansion early in snake evolution. Additionally, we provide some of the first links between secreted venom proteins, the genes that encode them, and their evolutionary origins in a rear-fanged colubrid snake, together with new genomic insight into the coevolutionary arms race between garter snakes and highly toxic newt prey that led to toxin resistance in garter snakes.


Assuntos
Evolução Molecular , Genoma , Anotação de Sequência Molecular , Comportamento Predatório , Serpentes/genética , Adaptação Fisiológica , Animais , Feminino , Células Fotorreceptoras de Vertebrados , Receptores Odorantes/genética , Répteis/classificação , Répteis/genética , Pigmentos da Retina/genética , Seleção Genética , Serpentes/classificação , Serpentes/fisiologia , Peçonhas/genética , Canais de Sódio Disparados por Voltagem/genética
18.
Curr Pharm Biotechnol ; 19(4): 308-335, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29929461

RESUMO

BACKGROUND: Research involving snake venom has gradually surpassed the simple discovery of new molecules using purification and structural characterization processes, and extended to the identification of their molecular targets and the evaluation of their therapeutic potential. Nevertheless, this only became possible due to constant progress in experimental biology and protein purification approaches. OBJECTIVE: This review aims to discuss the main components of snake venoms that have been investigated for biotechnological purposes, and to discover how these promising biomolecules were obtained with the satisfactory degree of purity that have enabled such studies. Advances in purification technologies of various snake venom molecules have allowed for important discoveries of proteins and peptides with different biomedical and biotechnological applications. RESULT AND CONCLUSION: It is believed that significant experimental and computational advances will arise in similar proportions in the coming years that will allow researchers to map the molecular regions responsible for their pharmacological actions, their respective mechanisms of action and their cell targets.


Assuntos
Venenos de Serpentes/química , Venenos de Serpentes/farmacologia , Serpentes/fisiologia , Animais , Descoberta de Drogas , Humanos , Proteínas/química , Venenos de Serpentes/genética , Venenos de Serpentes/uso terapêutico
19.
PLoS One ; 13(6): e0199377, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29949610

RESUMO

The royal python (Python regius) is commonly bred in captivity. To have a successful breeding season, accurate monitoring of the reproductive activity is necessary. The use of non-invasive monitoring methods in exotics is important in order to minimize stress. For this purpose ultrasound has been anecdotally used to monitor royal python reproductive activity. However, there is limited information regarding the reproductive cycle of this species. The aim of the present study is to monitor the female reproductive cycle of the royal python using ultrasonography and gonadal steroid metabolite measurements in the faeces. The reproductive activity of one hundred twenty-nine adult female P. regius was examined during two consecutive years. We performed brief scans on non-anaesthetized snakes using a portable ultrasound system and a 10-12 MHz linear array transducer (MyLab™ 30 Gold, Esaote). Ultrasound features, dimension and echogenicity of the reproductive structures were determined. During the second reproductive cycle, the hormonal profiles of 30 animals were also evaluated, with a monthly collection of faecal samples. These samples were classified according to reproductive stage, as identified by ultrasonographic examination, and the mean faecal progesterone and 17ß-estradiol levels were calculated using the results from an enzyme-linked immunosorbent assay (ELISA). Progesterone levels increased during the reproductive cycle. Estradiol levels showed greater variability, although they appeared to increase before coupling when compared to the levels between coupling and egg laying. The present study suggests that it is possible to identify different phases in the female royal python reproductive cycle: anovulatory phase, transition, folliculogenesis and embryogenesis. Ultrasound is also useful for identifying follicular regression or slugs. Gonadal steroid metabolite measurements from the faeces could help integrate reproductive information. The use of ultrasonography in addition to the steroid metabolite measurement in the faeces gives an accurate picture of ovarian activity in captive adult female royal pythons.


Assuntos
Fezes/química , Hormônios/metabolismo , Reprodução , Serpentes/fisiologia , Animais , Estradiol/metabolismo , Feminino , Progesterona/metabolismo , Ultrassonografia
20.
Toxicon ; 150: 151-167, 2018 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-29800609

RESUMO

With the threat of a post-antibiotic era looming, the search for new and effective antibiotics from novel sources is imperative. Not only has crude snake venom been shown to be effective, but specific components within the venoms, such as Phospholipase A2s and l-amino acid oxidases have been isolated and demonstrated to be effective as well. Despite numerous studies being completed on snake venoms, there is a heavy bias towards utilizing the venoms from the highly toxic Elapidae and Viperidae species. Very few studies have been conducted on the less toxic, but taxonomically more diverse, Colubridae. Furthermore, an extensive review of the literature examining the efficacy and potential specificity of these venoms has not been completed. Therefore, the aims of this study were to elucidate any similarities in snake venoms as well as investigate the efficacy of snake venom antimicrobial properties towards morphologically and metabolically diverse microbial classes and the prevalence of snake species with antimicrobial properties within each snake family. The results indicate that snake venoms and their isolated components are powerful antimicrobial agents but vary in efficacy towards different microbial classes. Furthermore, due to similarities in venom composition, and limited preliminary studies, the less toxic Colubridae family may be a fruitful area of research to find novel antimicrobial agents that are less harmful to humans.


Assuntos
Antibacterianos/farmacologia , Bactérias/efeitos dos fármacos , Venenos de Serpentes/química , Venenos de Serpentes/farmacologia , Serpentes/classificação , Animais , Antibacterianos/química , Análise por Conglomerados , Serpentes/fisiologia
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