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Nature Communications Aug 2023Three-finger toxins (3FTXs) are a functionally diverse family of toxins, apparently unique to venoms of caenophidian snakes. Although the ancestral function of 3FTXs is...
Three-finger toxins (3FTXs) are a functionally diverse family of toxins, apparently unique to venoms of caenophidian snakes. Although the ancestral function of 3FTXs is antagonism of nicotinic acetylcholine receptors, redundancy conferred by the accumulation of duplicate genes has facilitated extensive neofunctionalization, such that derived members of the family interact with a range of targets. 3FTXs are members of the LY6/UPAR family, but their non-toxin ancestor remains unknown. Combining traditional phylogenetic approaches, manual synteny analysis, and machine learning techniques (including AlphaFold2 and ProtT5), we have reconstructed a detailed evolutionary history of 3FTXs. We identify their immediate ancestor as a non-secretory LY6, unique to squamate reptiles, and propose that changes in molecular ecology resulting from loss of a membrane-anchoring domain and changes in gene expression, paved the way for the evolution of one of the most important families of snake toxins.
Topics: Animals; Three Finger Toxins; Phylogeny; Snakes; Toxins, Biological; Reptiles; Elapid Venoms; Evolution, Molecular
PubMed: 37567881
DOI: 10.1038/s41467-023-40550-0 -
American Journal of Veterinary Research Aug 2023The objective of this study was to determine bacterial flora throughout the gastrointestinal tract of a saltwater crocodile (Crocodylus porosus) using 16S rRNA gene...
OBJECTIVE
The objective of this study was to determine bacterial flora throughout the gastrointestinal tract of a saltwater crocodile (Crocodylus porosus) using 16S rRNA gene analysis.
ANIMALS
A convention on international trade in endangered species (CITES) of wild fauna and flora registered crocodile farm, provided a healthy male saltwater crocodile, Crocodylus porosus for this study.
PROCEDURES
Three samples were taken from the oral cavity, 3 samples from the proximal region of the small intestine (jejunum), and 3 samples from the distal part of the large intestine of the gastrointestinal tract of C. porosus were obtained using sterile cotton swabs. Next, swabs were placed in 15 mL sterile centrifuge tubes, individually, and kept on ice for immediate transportation to the laboratory. This was followed by 16S rRNA gene analysis using specific primers (341F-CCTAYGGGRBGCASCAG, and 806R-GGACTACNNGGGTATCTAAT). Amplicons were sequenced on Illumina paired-end platform, and bacterial gastrointestinal communities, the relative abundance of taxa, and principal component and coordinate analysis were performed.
RESULTS
The findings revealed that bacterial community structures from differing regions exhibited several differences. The number of observed bacterial operational taxonomic units (OTUs) was 153 in the oral cavity, 239 in the small intestine, and 119 in the large intestine of C. porosus. The small intestine reflects the highest richness. In contrast, the large intestine exhibited the least richness of microbial communities. Relative abundance of taxa showed that Proteobacteria, Bacteroidetes, and Firmicutes were dominant in all 3 sample sites. Pseudomonas differed in the oral cavity and the large intestine, with the latter exhibiting less distribution of Pseudomonas. Stenotrophomonas and Castellaniella were higher in the oral cavity, while the relative abundance of Comamonas and Salmonella was higher in the small intestine. Conversely, the relative abundance of Salmonella and Pannonibacter was augmented in the large intestine.
CLINICAL RELEVANCE
For the first time, this study demonstrates the bacterial diversity along the segments of the gastrointestinal tract of C. porosus. Bacterial flora varies throughout the gastrointestinal tract. Although further studies using large cohorts are warranted; however, our findings suggest that microbiome composition may have the potential as a biomarker in determining the overall health and well-being of C. porosus.
Topics: Male; Animals; Alligators and Crocodiles; RNA, Ribosomal, 16S; Commerce; Internationality; Gastrointestinal Tract; Bacteria
PubMed: 37353216
DOI: 10.2460/ajvr.23.03.0061 -
Scientific Reports Sep 2023The classical hypothesis proposes that the lack of recombination on sex chromosomes arises due to selection for linkage between a sex-determining locus and sexually...
The classical hypothesis proposes that the lack of recombination on sex chromosomes arises due to selection for linkage between a sex-determining locus and sexually antagonistic loci, primarily facilitated by inversions. However, cessation of recombination on sex chromosomes could be attributed also to neutral processes, connected with other chromosome rearrangements or can reflect sex-specific recombination patterns existing already before sex chromosome differentiation. Three Coleonyx gecko species share a complex XXXX/XXY system of sex chromosomes evolved via a fusion of the Y chromosome with an autosome. We analyzed synaptonemal complexes and sequenced flow-sorted sex chromosomes to investigate the effect of chromosomal rearrangement on recombination and differentiation of these sex chromosomes. The gecko sex chromosomes evolved from syntenic regions that were also co-opted also for sex chromosomes in other reptiles. We showed that in male geckos, recombination is less prevalent in the proximal regions of chromosomes and is even further drastically reduced around the centromere of the neo-Y chromosome. We highlight that pre-existing recombination patterns and Robertsonian fusions can be responsible for the cessation of recombination on sex chromosomes and that such processes can be largely neutral.
Topics: Female; Animals; Male; Lizards; Sex Chromosomes; Y Chromosome; Cell Movement; Recombination, Genetic
PubMed: 37726346
DOI: 10.1038/s41598-023-39937-2 -
PeerJ 2023Closely related species with ecological similarity often aggressively compete for a common, limited resource. This competition is usually asymmetric and results in one...
Closely related species with ecological similarity often aggressively compete for a common, limited resource. This competition is usually asymmetric and results in one species being behaviorally dominant over the other. Trade-offs between traits for behavioral dominance and alternative strategies can result in different methods of resource acquisition between the dominant and subordinate species, with important consequences for resource partitioning and community structure. Body size is a key trait thought to commonly determine behavioral dominance. Priority effects (., which species arrives at the resource first), however, can also determine the outcome of interactions, as can species-specific traits besides size that give an advantage in aggressive contests (., weapons). Here, we test among these three alternative hypotheses of body size, priority effects, and species identity for what determines the outcome of competitive interactions among two species of burying beetles, and . Both overlap in habitat and seasonality and exhibit aggressive competition over a shared breeding resource of small vertebrate carrion. In trials, we simulated what would happen upon the beetles' discovery of a carcass in nature by placing a carcass and one beetle of each species in a container and observing interactions over 13 h trials ( = 17 trials). We recorded and categorized interactions between beetles and the duration each individual spent in contact with the carcass (the key resource) to determine which hypothesis predicted trial outcomes. Body size was our only significant predictor; the largest species won most aggressive interactions and spent more time in contact with the carcass. Our results offer insight into the ecology and patterns of resource partitioning of and , the latter of which is unique among local for being a canopy specialist. is also unique among all in using snake eggs, in addition to other carrion, as a breeding resource. Our results highlight the importance of body size and related trade-offs in ecology and suggest parallels with other coexisting species and communities.
Topics: Animals; Coleoptera; Aggression; Ecosystem; Body Size; Snakes
PubMed: 38025751
DOI: 10.7717/peerj.16090 -
PloS One 2024Clinical assessment of body condition is crucial in captive and free-ranging reptiles, since a large percentage of diseases result from inadequate nutrition. However,...
Clinical assessment of body condition is crucial in captive and free-ranging reptiles, since a large percentage of diseases result from inadequate nutrition. However, preventive health care is restricted by the lack of a practical method for the assessment in tortoises. Pre-existing evaluation systems based on weight and shell measurements are laborious and ignore the clinical presentation of the animal. The present study aimed to facilitate the assessment by establishing a body condition score. A total of 373 Hermann's Tortoises (Testudo hermanni) (n = 281 tortoises kept as pets in Germany and n = 92 tortoises originating from a free-ranging population (68) or a rearing station (24) in France) were examined and data (weight (g), carapace length (cm), width (cm), height (cm)) were recorded in a standard protocol between October 2020 and October 2021. A modified version of a body condition score for Mojave Desert Tortoises (Gopherus agassizii) (1 = cachectic, 3 = ideal, 5 = obese) was utilized and tested against pre-existing shell measurement systems (Jackson's ratio, body condition index, volume condition index, circumferential product). German captive tortoises were significantly heavier and larger than French specimens. In the Spearman's correlation matrix, the body condition score showed a statistically significant correlation with all measurement methods in the total population of captive tortoises (Testudo hermanni boettgeri), with a medium correlation strength, and a lack of correlation in free-ranging tortoises (Testudo hermanni hermanni). However, individual animal data suggested misleading results of mathematical equations in terms of body condition. Clinical evaluation of tortoises, including a body condition score, should be considered essential to provide good healthcare and should be an integral part of general examination.
Topics: Animals; Turtles; France; Germany; Delivery of Health Care
PubMed: 38635596
DOI: 10.1371/journal.pone.0301892 -
Journal of Molecular Evolution Aug 2023Snake venom can vary both among and within species. While some groups of New World pitvipers-such as rattlesnakes-have been well studied, very little is known about the...
Snake venom can vary both among and within species. While some groups of New World pitvipers-such as rattlesnakes-have been well studied, very little is known about the venom of montane pitvipers (Cerrophidion) found across the Mesoamerican highlands. Compared to most well-studied rattlesnakes, which are widely distributed, the isolated montane populations of Cerrophidion may facilitate unique evolutionary trajectories and venom differentiation. Here, we describe the venom gland transcriptomes for populations of C. petlalcalensis, C. tzotzilorum, and C. godmani from Mexico, and a single individual of C. sasai from Costa Rica. We explore gene expression variation in Cerrophidion and sequence evolution of toxins within C. godmani specifically. Cerrophidion venom gland transcriptomes are composed primarily of snake venom metalloproteinases, phospholipase A[Formula: see text]s (PLA[Formula: see text]s), and snake venom serine proteases. Cerrophidion petlalcalensis shows little intraspecific variation; however, C. godmani and C. tzotzilorum differ significantly between geographically isolated populations. Interestingly, intraspecific variation was mostly attributed to expression variation as we did not detect signals of selection within C. godmani toxins. Additionally, we found PLA[Formula: see text]-like myotoxins in all species except C. petlalcalensis, and crotoxin-like PLA[Formula: see text]s in the southern population of C. godmani. Our results demonstrate significant intraspecific venom variation within C. godmani and C. tzotzilorum. The toxins of C. godmani show little evidence of directional selection where variation in toxin sequence is consistent with evolution under a model of mutation-drift equilibrium. Cerrophidion godmani individuals from the southern population may exhibit neurotoxic venom activity given the presence of crotoxin-like PLA[Formula: see text]s; however, further research is required to confirm this hypothesis.
Topics: Humans; Animals; Crotalinae; Viperidae; Crotoxin; Crotalid Venoms; Snake Venoms; Polyesters
PubMed: 37269364
DOI: 10.1007/s00239-023-10115-2 -
CNS Neuroscience & Therapeutics Oct 2023Gecko, the "sky dragon" named by Traditional Chinese Medicine, undergoes rapid coagulation and scarless regeneration following tail amputation in the natural ecology,...
AIMS
Gecko, the "sky dragon" named by Traditional Chinese Medicine, undergoes rapid coagulation and scarless regeneration following tail amputation in the natural ecology, providing a perfect opportunity to develop the efficient and safe drug for blood clotting. Here, gecko thrombin (gthrombin) was recombinantly prepared and comparatively studied on its procoagulant activity.
METHODS
The 3D structure of gthrombin was constructed using the homology modeling method of I-TASSER. The active gthrombin was prepared by the expression of gecko prethrombin-2 in 293 T cells, followed by purification with Ni -chelating column chromatography prior to activation by snake venom-derived Ecarin. The enzymatic activities of gthrombin were assayed by hydrolysis of synthetic substrate S-2238 and the fibrinogen clotting. The vulnerable nerve cells were used to evaluate the toxicity of gthrombin at molecular and cellular levels.
RESULTS
The active recombinant gthrombin showed super-high catalytic and fibrinogenolytic efficiency than those of human under different temperatures and pH conditions. In addition, gthrombin made nontoxic effects on the central nerve cells including neurons, contrary to those of mammalian counterparts, which contribute to neuronal damage, astrogliosis, and demyelination.
CONCLUSIONS
A super-high activity but safe procoagulant candidate drug was identified from reptiles, which provided a promising perspective for clinical application in rapid blood clotting.
Topics: Animals; Humans; Thrombin; Blood Coagulation; Lizards; Mammals
PubMed: 37144588
DOI: 10.1111/cns.14250 -
PeerJ 2023Using modern ichnological and stratigraphic tools, we reinvestigate two iconic sauropodomorph-attributed tetradactyl ichnogenera, and , and their stratigraphic...
Using modern ichnological and stratigraphic tools, we reinvestigate two iconic sauropodomorph-attributed tetradactyl ichnogenera, and , and their stratigraphic occurrences in the middle Upper Triassic of Lesotho. These tracks have been reaffirmed and are stratigraphically well-constrained to the lower Elliot Formation (Stormberg Group, Karoo Basin) with a maximum depositional age range of <219-209 Ma (Norian). This represents the earliest record of basal sauropodomorph trackways in Gondwana, if not globally. Track and trackway morphology, the sedimentary context of the tracks, and unique features (., drag traces) have enabled us to discuss the likely limb postures and gaits of the trackmakers. has bipedal (. ) and quadrupedal (. ) trackway states, with the oldest quadrupedal track and trackway parameters suggestive of a columnar, graviportal limb posture in the trackmaker. Moreover, an irregularity in the intermanus distance and manus orientation and morphology, in combination with drag traces, is indicative of a non-uniform locomotory suite or facultative quadrupedality. Contrastingly, , the youngest trackway, has distinctive medially deflected, robust pedal and manual claw traces and a wide and uniform intermanus distance relative to the interpedal. These traits suggest a quadrupedal trackmaker with clawed and fleshy feet and forelimbs held in a wide, flexed posture. Altogether, these trackways pinpoint the start of the southern African ichnological record of basal sauropodomorphs with bipedal and quadrupedal locomotory habits to, at least, c. 215 Ma in the middle Late Triassic.
Topics: Animals; Fossils; Dinosaurs; Locomotion; Gait; Lesotho
PubMed: 37790620
DOI: 10.7717/peerj.15970 -
PloS One 2023High temperatures and low water availability often strike organisms concomitantly. Observing how organisms behaviorally thermohydroregulate may help us to better...
High temperatures and low water availability often strike organisms concomitantly. Observing how organisms behaviorally thermohydroregulate may help us to better understand their climatic vulnerability. This is especially important for tropical forest lizards, species that are purportedly under greater climatic risk. Here, we observed the influence of hydration level on the Voluntary Thermal Maximum (VTmax) in two small Amazonian lizard species: Loxopholis ferreirai (semiaquatic and scansorial) and Loxopholis percarinatum (leaf litter parthenogenetic dweller), accounting for several potential confounding factors (handling, body mass, starting temperature and heating rate). Next, we used two modeling approaches (simple mapping of thermal margins and NicheMapR) to compare the effects of dehydration, decrease in precipitation, ability to burrow, and tree cover availability, on geographic models of climatic vulnerability. We found that VTmax decreased with dehydration, starting temperature, and heating rates in both species. The two modeling approaches showed that dehydration may alter the expected intensity, extent, and duration of perceived thermal risk across the Amazon basin for these forest lizards. Based on our results and previous studies, we identify new evidence needed to better understand thermohydroregulation and to model the geography of climatic risk using the VTmax.
Topics: Animals; Lizards; Dehydration; Body Temperature Regulation; Body Temperature; Temperature; Geography
PubMed: 37910524
DOI: 10.1371/journal.pone.0286502 -
Toxins Aug 2023Snake venom research has historically focused on front-fanged species (Viperidae and Elapidae), limiting our knowledge of venom evolution in rear-fanged snakes across...
Snake venom research has historically focused on front-fanged species (Viperidae and Elapidae), limiting our knowledge of venom evolution in rear-fanged snakes across their ecologically diverse phylogeny. Three-finger toxins (3FTxs) are a known neurotoxic component in the venoms of some rear-fanged snakes (Colubridae: Colubrinae), but it is unclear how prevalent 3FTxs are both in expression within venom glands and more broadly among colubrine species. Here, we used a transcriptomic approach to characterize the venom expression profiles of four species of colubrine snakes from the Neotropics that were dominated by 3FTx expression (in the genera , , , and ). By reconstructing the gene trees of 3FTxs, we found evidence of putative novel heterodimers in the sequences of and , revealing an instance of parallel evolution of this structural change in 3FTxs among rear-fanged colubrine snakes. We also found positive selection at sites within structural loops or "fingers" of 3FTxs, indicating these areas may be key binding sites that interact with prey target molecules. Overall, our results highlight the importance of exploring the venoms of understudied species in reconstructing the full evolutionary history of toxins across the tree of life.
Topics: Animals; Colubridae; Three Finger Toxins; Binding Sites; Gene Expression Profiling; Neurotoxicity Syndromes
PubMed: 37755949
DOI: 10.3390/toxins15090523