Snake venom bioprospecting as an approach to finding potential anti-glioblastoma molecules.

Glioblastoma (GB) is the most common type of malignant tumor of the central nervous system, responsible for significant morbidity and with a 5-year overall relative survival of only 6.8%. Without advances in treatment in the last twenty years, the standard of care continues to be maximum safe resection, Temozolomide (TMZ), and radiotherapy. Many new trials are ongoing, and despite showing increased progression-free survival, these trials did not improve overall survival. They did not consider the adverse effects of these therapies. Therefore, an increasing number of bioprospecting studies have used snake venom molecules to search for new strategies to attack GB selectively without producing side effects. The present review aims to describe GB characteristics and current and new approaches for treatment considering their side effects. Besides, we focused on the antitumoral activity of snake venom proteins from the Viperidae family against GB, exploring the potential for drug design based on in vitro and in vivo studies. This review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. In January 2024, a systematic search was performed in the PubMed, EMBASE, and Web of Science databases from January 2000 to December 2023. Search terms were selected based on the population/exposure/outcome (PEO) framework and combined using Boolean operators ("AND", "OR"). The search strategy used these terms: glioblastoma, glioma, high-grade glioma, WHO IV glioma, brain cancer, snake venom, Viperidae, and bioprospection. We identified 10 in vivo and in vitro studies with whole and isolated proteins from Viperidae venom that could have antitumor activity against glioblastoma. Studies in bioprospecting exploring the advantage of snake venom proteins against GB deserve to be investigated due to their high specificity, small size, inherent bioactivity, and few side effects to cross the blood-brain barrier (BBB) to reach the tumor microenvironment.

The annual ovarian cycle in Northern pit vipers (Bothrops atrox) using serum steroids and ultrasound of the female reproductive tract.

Knowledge on hormonal regulation of reproductive cycles in viperid snakes is still incipient, especially when it comes to females and tropical species. There is an urgent need to understand the reproduction of venomous snakes to improve assisted reproduction techniques and optimize the maintenance of these animals in captivity. With this in mind, we monitored Northern pit viper females year-round throughout different seasons via serum levels of progesterone (P4) and estradiol (E2) in conjunction with ultrasound examinations. Ovarian follicles were classified according to their size and stage of vitellogenesis in F-I and F-II (non-vitellogenic phase) or in F-III and F-IV (vitellogenic phase). During autumn and winter, five adult males were rotated among these females for reproductive pairing, which resulted in 17 copulations and 2 pregnancies in the first year and 12 copulations and 5 pregnancies in the second year. Then, we assessed changes in P4 and E2 levels according to seasons, predominant ovarian structures and the presence of embryos or eggs in the oviduct. Our findings showed high levels of E2 when a greater number of vitellogenic follicles were detected, indicating a possible influence of E2 on vitellogenesis and higher levels of P4 whenever eggs and embryos were visualized in the oviduct, implying its role in maintaining pregnancy. Descriptive analysis of the vipers' ovarian cycles revealed a greater number of vitellogenic follicles during winter, probably as a result of increases in E2; whereas pregnancies occurred predominantly in spring, under the influence of P4. The use of ultrasound images, as a minimally invasive methodology, associated with serum steroid levels has proven to be an efficient approach in the reproductive monitoring of Northern pit vipers in vivo. In addition, these data suggest that female pit vipers under human care display a seasonal reproductive cycle, despite earlier studies involving captive males of the species indicating a lack of seasonality in sperm production and quality.

Suspected envenomation by the common European adder (Vipera berus berus) in 28 horses in Finland.

Vipera berus berus is the only venomous snake present in the Nordic countries and cases of envenomation in horses are reported during the warmer months. Little is known about the presentation, treatment and survival of horses with common European adder envenomation. Clinical and laboratory findings, treatment and outcome are reported for 28 horses admitted to Helsinki University Equine Hospital in 2008-2023 due to suspicion of snake bite. Eleven of these horses received antivenom treatment. Other common treatments included non-steroidal anti-inflammatories (22/28), antimicrobials (19/28), intravenous fluid therapy (11/28), corticosteroids (9/28) and local treatment (11/28). All horses survived until discharge. No difference was detected in the length of hospital stay between horses with moderate envenomation that had or had not received antivenom treatment. Horses with moderate envenomation are more likely to receive antivenom treatment and require longer hospital stay than horses with mild envenomation. Antivenom treatment is not associated with shorter hospital stay. Little evidence supports the use of corticosteroids and antibiotics in treatment of envenomation. Studies with larger numbers of animals are warranted to evaluate the effect of treatment, including administration of antivenom, on long-term outcome and survival from envenomation.

The tale of the rattle: Using rattle size to understand growth and sexual dimorphism in an insular population of rattlesnakes (Crotalus oreganus caliginis).

Islands have played a key role in our understanding of rapid evolution. A large body of literature has examined morphological changes in response to insularity and isolation, which has yielded useful generalizations about how animals can adapt to live in very small geographic areas. However, understanding the evolution of morphological variation in insular populations often requires detailed data sets on longitudinal patterns of growth and development, and such studies typically necessitate long-term mark-recapture on a large sample of individuals. Rattlesnakes provide a unique opportunity to address some of these difficulties because the addition of rattle segments to the rattle string occurs with regular periodicity and their size directly correlates with the body size of the snake at the time of the ecdysis cycle generating the segment. Here, we used a large database of rattle segment sizes recorded from island (Isla Coronado Sur, Baja California, Mexico) and mainland (Camp Pendleton, California, United States) populations of Western Rattlesnakes (Crotalus oreganus and C. o. caliginis) that separated approximately 10,000 years ago to compare body sizes at different ecdysis cycles, which allowed us to assess differences in growth rates and patterns of sexual size dimorphism. Our results show that rattlesnakes on Isla Coronado Sur appear to be born smaller and grow more slowly than their mainland counterparts, resulting in a "dwarfed" island population. However, despite significant differences in body size, both populations exhibited the same degree of sexual dimorphism. Our study demonstrates the potential to use rattle characteristics to recover detailed estimates of fundamental demographic parameters.

A Guide to the Clinical Management of Vipera Snakebite in Italy.

The genus Vipera encompasses most species of medically significant venomous snakes of Europe, with Italy harbouring four of them. Envenomation by European vipers can result in severe consequences, but underreporting and the absence of standardised clinical protocols hinder effective snakebite management. This study provides an updated, detailed set of guidelines for the management and treatment of Vipera snakebite tailored for Italian clinicians. It includes taxonomic keys for snake identification, insights into viper venom composition, and recommendations for clinical management. Emphasis is placed on quick and reliable identification of medically relevant snake species, along with appropriate first aid measures. Criteria for antivenom administration are outlined, as well as indications on managing potential side effects. While the protocol is specific to Italy, its methodology can potentially be adapted for other European countries, depending on local resources. The promotion of comprehensive data collection and collaboration among Poison Control Centres is advocated to optimise envenomation management protocols and improve the reporting of epidemiological data concerning snakebite at the country level.

One-Step Affinity Purification of Leucine-Rich α2-Glycoproteins from Snake Sera and Characterization of Their Phospholipase A2-Inhibitory Activities as ß-Type Phospholipase A2 Inhibitors.

Snakes contain three types of phospholipase A2 (PLA2)-inhibitory proteins in their blood, PLIα, ß, and γ, which protect them from their own venom, PLA2. PLIß is the snake ortholog of leucine-rich α2 glycoprotein (LRG). Since autologous cytochrome c (Cyt c) serves as an endogenous ligand for LRG, in this study, we purified snake LRGs from various snake serum samples using Cyt c affinity chromatography. All purified snake LRGs were found to be dimers linked by disulfide bonds. Laticauda semifasciata and Naja kaouthia LRGs showed no inhibitory activity against L. semifasciata PLA2 and weak inhibitory activity against Gloydius brevicauda basic PLA2. Elaphe climacophora PLIß had weaker inhibitory activity against G. brevicauda basic PLA2 than G. brevicauda and Elaphe quadrivirgata PLIs, which are abundant in blood and known to neutralize G. brevicauda basic PLA2. Protobothrops flavoviridis LRG showed no inhibitory activity against basic venom PLA2, PL-X, or G. brevicauda basic PLA2. Binding analysis of P. flavoviridis LRG using surface plasmon resonance showed very strong binding to snake Cyt c, followed by that to horse Cyt c, weak binding to yeast Cyt c, and no binding to P. flavoviridis PL-X or BPI/II. We also deduced the amino acid sequences of L. semifasciata and P. flavoviridis LRG by means of cDNA sequencing and compared them with those of other known sequences of PLIs and LRGs. This study concluded that snake LRG can potentially inhibit basic PLA2, but, whether it actually functions as a PLA2-inhibitory protein, PLIß, depends on the snake.

Potential Biotechnological Applications of Venoms from the Viperidae Family in Central America for Thrombosis.

Central America is home to one of the most abundant herpetofauna in the Americas, occupying only 7% of the continent's total area. Vipers and lizards are among the most relevant venomous animals in medical practice due to the consequences of envenomation from the bite of these animals. A great diversity of biomolecules with immense therapeutic and biotechnological value is contained in their venom. This paper describes the prominent leading representatives of the family Viperidae, emphasizing their morphology, distribution, habitat, feeding, and venom composition, as well as the biotechnological application of some isolated components from the venom of the animals from these families, focusing on molecules with potential anti-thrombotic action. We present the leading protein families that interfere with blood clotting, platelet activity, or the endothelium pro-thrombotic profile. In conclusion, Central America is an endemic region of venomous animals that can provide many molecules for biotechnological applications.

Paradoxical Exception to Island Tameness: Increased Defensiveness in an Insular Population of Rattlesnakes.

Island tameness results largely from a lack of natural predators. Because some insular rattlesnake populations lack functional rattles, presumably the consequence of relaxed selection from reduced predation, we hypothesized that the Santa Catalina Island, California, USA, population of the southern Pacific rattlesnake (Crotalus helleri, which possesses a functional rattle), would exhibit a decrement in defensive behavior relative to their mainland counterparts. Contrary to our prediction, rattlesnakes from the island not only lacked tameness compared to mainland snakes, but instead exhibited measurably greater levels of defensiveness. Island snakes attempted to bite 4.7 times more frequently as we endeavored to secure them by hand, and required 2.1-fold more time to be pinned and captured. When induced to bite a beaker after being grasped, the island snakes also delivered 2.1-fold greater quantities of venom when controlling for body size. The additional venom resulted from 2.1-fold larger pulses of venom ejected from the fangs. We found no effects of duration in captivity (2-36 months), which suggests an absence of long-term habituation of antipredator behaviors. Breeding bird surveys and Christmas bird counts indicated reduced population densities of avian predators on Catalina compared to the mainland. However, historical estimates confirmed that populations of foxes and introduced mammalian predators (cats and pigs) and antagonists (herbivorous ungulates) substantially exceeded those on the mainland in recent centuries, and therefore best explain the paradoxically exaggerated defensive behaviors exhibited by Catalina's rattlesnakes. These findings augment our understanding of anthropogenic effects on the behaviors of island animals and underscore how these effects can negatively affect human safety.

Female long-term sperm storage results in viable offspring in the Himalayan Mountain Pitviper, Ovophis monticola.

The ability of females to store sperm for extended periods in their reproductive tracts (termed long-term sperm storage, LTSS) has been reported across a diversity of vertebrate taxa. The evolutionary, ecological, and physiological significance of LTSS is wide-ranging and includes the ability to produce offspring when mates may be temporally scarce by way of decoupling copulation from ovulation, inbreeding avoidance, and the generation and maintenance of genetic diversity in progeny. Among vertebrate lineages, nonavian reptiles exhibit a remarkable capacity for LTSS, with the production of viable offspring reported after periods exceeding 6 years since prior contact with a potential mate. Given that female reptiles are able to store viable sperm for prolonged periods, it is important to disentangle LTSS from that of facultative parthenogenesis (FP), a reproductive trait which appears widespread among all reptile lineages. The implications of this distinction are particularly important in the context of the development and management of captive breeding programs. To accurately determine between the two reproductive strategies, genomic screening is highly recommended. Following a period of isolation for 13 months from a potential male mate, a female Himalayan Mountain Pitviper (Ovophis monticola) produced a clutch of three male offspring. Here, through genome-scale analyses of the female and her progeny, we document the first record of LTSS in this genus and exclude FP as the alternative hypothesis.

Hidden in the sand: Phylogenomics unravel an unexpected evolutionary history for the desert-adapted vipers of the genus Cerastes.

The desert vipers of the genus Cerastes are a small clade of medically important venomous snakes within the family Viperidae. According to published morphological and molecular studies, the group is comprised by four species: two morphologically similar and phylogenetically sister taxa, the African horned viper (Cerastes cerastes) and the Arabian horned viper (Cerastes gasperettii); a more distantly related species, the Saharan sand viper (Cerastes vipera), and the enigmatic Böhme's sand viper (Cerastes boehmei), only known from a single specimen in captivity allegedly captured in Central Tunisia. In this study, we sequenced one mitochondrial marker (COI) as well as genome-wide data (ddRAD sequencing) from 28 and 41 samples, respectively, covering the entire distribution range of the genus to explore the population genomics, phylogenomic relationships and introgression patterns within the genus Cerastes. Additionally, and to provide insights into the mode of diversification of the group, we carried out niche overlap analyses considering climatic and habitat variables. Both nuclear phylogenomic reconstructions and population structure analyses have unveiled an unexpected evolutionary history for the genus Cerastes, which sharply contradicts the morphological similarities and previously published mitochondrial approaches. Cerastes cerastes and C. vipera are recovered as sister taxa whilst C. gasperettii is a sister taxon to the clade formed by these two species. We found a relatively high niche overlap (OI > 0.7) in both climatic and habitat variables between C. cerastes and C. vipera, contradicting a potential scenario of sympatric speciation. These results are in line with the introgression found between the northwestern African populations of C. cerastes and C. vipera. Finally, our genomic data confirms the existence of a lineage of C. cerastes in Arabia. All these results highlight the importance of genome-wide data over few genetic markers to study the evolutionary history of species.

The annual ovarian cycle in Northern Pit Vipers (Bothrops atrox) using serum steroids and ultrasound of the female reproductive tract

Knowledge on hormonal regulation of reproductive cycles in viperid snakes is still incipient, especially when it comes to females and tropical species. There is an urgent need to understand the reproduction of venomous snakes to improve assisted reproduction techniques and optimize the maintenance of these animals in captivity. With this in mind, we monitored Northern pit viper females year-round throughout different seasons via serum levels of progesterone (P4) and estradiol (E2) in conjunction with ultrasound examinations. Ovarian follicles were classified according to their size and stage of vitellogenesis in F-I and F-II (non-vitellogenic phase) or in F-III and F-IV (vitellogenic phase). During autumn and winter, five adult males were rotated among these females for reproductive pairing, which resulted in 17 copulations and 2 pregnancies in the first year and 12 copulations and 5 pregnancies in the second year. Then, we assessed changes in P4 and E2 levels according to seasons, predominant ovarian structures and the presence of embryos or eggs in the oviduct. Our findings showed high levels of E2 when a greater number of vitellogenic follicles were detected, indicating a possible influence of E2 on vitellogenesis and higher levels of P4 whenever eggs and embryos were visualized in the oviduct, implying its role in maintaining pregnancy. Descriptive analysis of the vipers’ ovarian cycles revealed a greater number of vitellogenic follicles during winter, probably as a result of increases in E2; whereas pregnancies occurred predominantly in spring, under the influence of P4. The use of ultrasound images, as a minimally invasive methodology, associated with serum steroid levels has proven to be an efficient approach in the reproductive monitoring of Northern pit vipers in vivo. In addition, these data suggest that female pit vipers under human care display a seasonal reproductive cycle, despite earlier studies involving captive males of the species indicating a lack of seasonality in sperm production and quality.

Ontogenetic and sexual differences in the venom of Bothrops moojeni: insights from a litter and its mother / Diferenças ontogenéticas e sexuais no veneno de Bothrops moojeni: percepções de uma ninhada e de sua mãe

Variability in snake venom composition is well-documented and crucial for understanding snake ecology and predicting snakebites. In this study, we characterize the venom composition and biological activities of newborn female and male Bothrops moojeni and their mother. Our results reveal significant differences between the venom of newborn females and males, demonstrating a broad and diverse range of proteins. The venoms of newborn females showed higher serine protease effects, increased hemorrhagic activity, and greater lethality compared to the venom of newborn males. However, no differences were observed in phospholipase A2 and coagulant activity. The differences in protein composition and toxic activities between maternal and neonatal venom, as well as between the venoms of newborn females and males, contribute to understanding the diverse outcomes of snakebites. These results underscore the importance of considering sex and ontogeny in understanding venom composition in snakes.

A variabilidade na composição dos venenos de serpentes é bem documentada e crucial para a compreensão da ecologia das serpentes ou do prognóstico dos envenenamentos ofídicos. Nesse estudo, caracterizamos a composição e a atividade biológica do veneno de fêmeas e machos recém-nascidos e sua mãe. Nossos resultados revelaram diferenças significativas entre o veneno de fêmeas e machos recém-nascidos, demonstrando uma ampla e diversificada gama de proteínas. Os venenos de fêmeas recém-nascidas apresentaram mais efeitos de serina protease, aumento da atividade hemorrágica e maior letalidade em comparação ao veneno dos machos recém-nascidos. No entanto, nenhuma diferença foi observada na fosfolipase A2 e na atividade coagulante. As diferenças na composição proteica e nas atividades tóxicas entre o veneno materno e neonatal, bem como entre os venenos de fêmeas e machos recém-nascidos contribuem para a compreensão dos diversos resultados dos acidentes ofídicos. Esses resultados ressaltam a importância de considerar o sexo e a ontogenia na compreensão da composição do veneno desses animais.

Snake venom Metalloproteases na família Viperidae: revisão narrativa com ênfase no Gênero Bothrops

With distribution across almost the entire globe, the Viperidae family can be described as one of the most sophisticated groups of venomous animals when it comes to the inoculation of their toxins, due to the presence of highly efficient hollow fangs in both predation or defense scenarios. Unfortunately, due to agricultural expansion and the destruction of their natural habitats, encounters between vipers and humans, especially in rural contexts, are a severe reality in many communities, currently being classified by the World Health Organization as a Neglected Tropical Disease. Enhancing the problem, the toxins composing the venoms of vipers are notoriously known for their debilitating activity, sometimes leading to permanent damage to limbs or even amputations, causing substantial losses not only to the incapacitated victim but also to the economically dependent family unit. This potential of the venom is the result of the synergy of a myriad of toxins that, together, generate the clinical manifestation of envenoming. Within vipers, the presence of proteolytic enzymes is abundant, strongly associated with critical pathological manifestations such as necrosis and hemorrhage. Crucial among these proteases, Snake Venom Metalloproteases (SVMPs), zinc-associated metalloproteases, represent a robust portion of the venom of many vipers and are widely recognized for causing hemorrhage due to their action on the basement membrane of blood vessels, as well as their ability to generate coagulopathies. These toxins are important not only for their specific actions but also in amplifying the damage caused by other toxin families present in the venom, reinforcing the need to elucidate their mechanisms not only for the improvement of therapeutic techniques but also for their intrinsic value in the natural history of these animals.

Com distribuição por quase todo o globo, a família Viperidae pode ser descrita como um dos grupos de animais peçonhentos com a mais sofisticada especialização quando se trata da inoculação de suas toxinas, graças à presença de presas ocas altamente eficientes em situações de predação ou defesa. Infelizmente, devido à expansão agrícola e à destruição dos habitats naturais destes animais, o encontro de víboras com humanos, principalmente em contextos rurais, é uma realidade severa em muitas comunidades, sendo atualmente considerado pela Organização Mundial da Saúde como uma Doença Tropical Negligenciada. Potencializando o problema, as toxinas que compõem as peçonhas de viperídeos são notoriamente conhecidas por sua propriedade debilitante, por vezes acarretando em danos permanentes a membros ou mesmo amputações, causando perdas substanciais não somente à vítima incapacitada para o trabalho, mas ao núcleo familiar economicamente dependente. Tal potencial presente na peçonha pode ser entendido graças à sinergia de uma miríade de toxinas que, em conjunto, geram o quadro clínico do envenenamento. Dentro dos viperídeos, é abundante a presença de enzimas proteolíticas, fortemente associadas a manifestações patológicas críticas como necrose e hemorragia. Crucial entre as proteases, as Snake Venom Metalloproteases (SVMP), metaloproteases associadas a uma molécula de zinco, representam uma porção robusta da peçonha de muitas víboras e são amplamente reconhecidas por causarem hemorragia devido à sua ação na membrana basal de vasos sanguíneos, bem como à capacidade em gerar coagulopatias. Tais toxinas são importantes não somente por sua ação especializada, mas também em amplificar os danos causados por outras famílias de toxinas presentes na peçonha, reforçando a necessidade da elucidação de seus mecanismos não somente para a melhoria de técnicas terapêuticas, mas também por seu valor intrínseco na história natural destes animais.

Food preference for native and invasive prey in the naive lancehead pitviper

The presence of invasive species in the environment can be highly detrimental. The success of these species depends on their interaction with native ones. The prey–predator relationship between invasive and native species can result in biodiversity loss or the introduction of new food items for local predators. Due to its tropical and extensive nature, Brazil is vulnerable to the colonization of invasive species. Snakes are a group of animals that can act as both predators and prey for invasive species. The pitviper Bothrops jararaca is an abundant and widely distributed native species on the Brazilian coast. Based on this, we conducted a study on the feeding preferences of naive B. jararaca juveniles regarding invasive and native prey. We found that this species exhibits a greater preference for native anurans compared to Rana catesbeiana, an invasive amphibian associated with significant environmental impacts. Additionally, the gecko Hemidactylus mabouia, a prey that triggered intense predatory responses from the pitviper, reveals that this species, even with a short period of coexistence with B. jararaca, has established an intense prey–predator relationship. The negative correlation between prey size and feeding interest, guided solely by olfactory cues, adds a layer of complexity to understanding the feeding choices of B. jararaca, providing valuable insights for conservation and environmental management strategies.

Proteomic characteristics of six snake venoms from the Viperidae and Elapidae families in China and their relation to local tissue necrosis.

Patients envenomed by snakes from the Viperidae and Elapidae families in China often have varying degrees of local tissue necrosis. Due to the relative clinical characteristics of local tissue necrosis and ulceration following envenoming, this study has analyzed the proteome of six snake venoms from the Viperidae and Elapidae family, and the toxin profiles of each snake were compared and correlated with the clinical manifestations that follow cytotoxic envenoming. Deinagkistrodon acutus and Naja atra envenomation induce severe ulceration, which is absent in Bungarus multicinctus envenomation and mild in the other three vipers. It is interesting to note that the proportion of c-type lectins (CTL) (20.63%) in Deinagkistrodon acutus venom was relatively high, which differs from the venom of other vipers. In addition, three-fingered toxin (3FTx) (2.15%) is present in the venom of Deinagkistrodon acutus, but has not been detected in the remaining three vipers. Snake venom metalloprotease (SVMP) (34.4%-44.7%), phospholipase A2 (PLA2) (9.81%-40.83%), and snake venom serine protease (SVSP) (9.44%-16.2%) represent the most abundant families of toxin in Viperidae venom. The Elapidae venom proteome was mainly composed of neurotoxins and cytotoxins, including 3FTx (39.28%-60.08%) and PLA2 (8.24%-58.95%) toxins, however, the proportion of CRISPS (26.36%) in Naja atra venom was relatively higher compared to Bungarus multicinctus venom. Significant differences in SVMP, SVSP, and 3FTx expression levels exist between the Viperidae and the Elapidae family. The main toxins responsible for the development of tissue necrosis and ulcerations following Viperidae envenoming are hematotoxins (SVSMP, SVSP) and myotoxins (PLA2). Deinagkistrodon acutus venom contains high levels of CTL and traces of 3FTx, leading to more severe local necrosis. However, Naja atra venom can also cause severe local necrosis through the effects of myotoxin (3FTx, CRISP, PLA2). Bungarus multicinctus venom does not contain myotoxins, resulting in pure systemic neurological manifestations no obvious necrosis of local tissue in patients.

Composition characterization of various viperidae snake venoms using MS-based proteomics N-glycoproteomics and N-glycomics.

Viperidae snake species is widely abundant and responsible for most envenomation cases in Turkey. The structural and compositional profiles of snake venom have been investigated to study the venom component variation across different species and to profile the venom biological activity variation against prey. In this context, we used proteomics, glycoproteomics and glycomics strategies to characterize the protein, glycoproteins and glycan structural and compositional profiles of various snake venoms in the Viperidae family. Moreover, we compared these profiles using the downstream bioinformatics and machine learning classification modules. The overall mass spectrometry profiles identified 144 different proteins, 36 glycoproteins and 78 distinct N-glycan structures varying in composition across the five venoms. A high amount of the characterized proteins belongs to the glycosylated protein family Trypsin-like serine protease (Tryp_SPc), Disintegrin (DISIN), and ADAM Cysteine-Rich (ACR). Most identified N-glycans have a complex chain carrying galactosylated N-glycans abundantly. The glycan composition data obtained from glycoproteomics aligns consistently with the findings from glycomics. The clustering and principal component analyses (PCA) illustrated the composition-based similarities and differences between each snake venom species' proteome, glycoproteome and glycan profiles. Specifically, the N-glycan profiles of M. xanthina (Mx) and V. a. ammodytes (Vaa) venoms were identical and difficult to differentiate; in contrast, their proteome profiles were distinct. Interestingly, the variety of the proteins across the species highlighted the impact of glycosylation on the diversity of the glycosylated protein families. This proposed high throughput approach provides accurate and comprehensive profiles of the composition and function of various Viperidae snake venoms.

A genome assembly for the southern Pacific rattlesnake, Crotalus oreganus helleri, in the western rattlesnake species complex.

Rattlesnakes play important roles in their ecosystems by regulating prey populations, are involved in complex coevolutionary dynamics with their prey, and exhibit a variety of unusual adaptations, including maternal care, heat-sensing pit organs, hinged fangs, and medically-significant venoms. The western rattlesnake (Crotalus oreganus) is one of the widest ranging rattlesnake species, with a distribution from British Columbia, where it is listed as threatened, to Baja California and east across the Great Basin to western Wyoming, Colorado and New Mexico. Here, we report a new reference genome assembly for one of six currently recognized subspecies, C. oreganus helleri, as part of the California Conservation Genomics Project (CCGP). Consistent with the reference genomic sequencing strategy of the CCGP, we used Pacific Biosciences HiFi long reads and Hi-C chromatin-proximity sequencing technology to produce a de novo assembled genome. The assembly comprises a total of 698 scaffolds spanning 1,564,812,557 base pairs, has a contig N50 of 64.7 Mb, a scaffold N50 of 110.8 Mb, and BUSCO complete score of 90.5%. This reference genome will be valuable for studies on the genomic basis of venom evolution and variation within Crotalus, in resolving the taxonomy of C. oreganus and its relatives, and for the conservation and management of rattlesnakes in general.

Exotic (non-native) snakebite envenomation in Japan: A review of the literature between 2000 and 2022.

A limited number of studies have investigated the clinical characteristics of snakebite envenomation by exotic (non-native) snakes in Japan. This study reviewed the literature to determine the status and risk of bites by exotic pet snakes in Japan. We reviewed reports of snakebite due to exotic snakes in Japan published between 2000 and 2022, excluding reports of bites by snakes native to Japan, such as Gloydius blomhoffii, Rhabdophis tigrinus, and Protobothrops flavoviridis. During the study period, 11 exotic snakebites were recorded, involving 11 species. The majority of those bitten (10/11 cases) were male, all cases were hand injuries, and there were no fatalities. The snakes responsible belonged to the Colubridae (4/11 cases), Viperidae (4/11 cases), and Elapidae (3/11 cases) families. Cases of envenomation by G. brevicaudus, Bungarus candidus, and Dendroaspis angusticeps were of particular interest. Ten of the eleven patients developed local cytotoxic signs, and three developed "compartment syndrome," in which the surgeons performed decompressive incisions. Two bites from elapid snakes and one from a viperid snake resulted in respiratory failure. Antivenom was given in two cases. Complications were observed, such as acute kidney injury, rhabdomyolysis, coagulopathy, and residual dysfunction of the affected finger. Emergency rooms should be prepared to manage patients who have been bitten by exotic snakes, even though the number of reported cases is not high in Japan. Initial stabilization of patients is crucial, before a definitive diagnosis is made, as with native snakebite envenomation. Finger bites are reported in most cases, which may result in functional impairment of the fingers. In order to collect more comprehensive patient data in Japan, a reporting system for all snakebite envenomations should be considered.

Medically important snakes and snakebite envenoming in Iran.

Snakebite is a relatively common health condition in Iran with a diverse snake fauna, especially in tropical southern and mountainous western areas of the country with a plethora of snake species. The list of medically important snakes, circumstances and effects of their bite, and necessary medical care require critical appraisal and should be updated regularly. This study aims to review and map the distributions of medically important snake species of Iran, re-evaluate their taxonomy, review their venomics, describe the clinical effects of envenoming, and discuss medical management and treatment, including the use of antivenom. Nearly 350 published articles and 26 textbooks with information on venomous and mildly venomous snake species and snakebites of Iran, were reviewed, many in Persian (Farsi) language, making them relatively inaccessible to an international readership. This has resulted in a revised updated list of Iran's medically important snake species, with taxonomic revisions of some, compilation of their morphological features, remapping of their geographical distributions, and description of species-specific clinical effects of envenoming. Moreover, the antivenom manufactured in Iran is discussed, together with treatment protocols that have been developed for the hospital management of envenomed patients.

Conservation of Major Satellite DNAs in Snake Heterochromatin.

Repetitive DNA sequences constitute a sizeable portion of animal genomes, and tandemly organized satellite DNAs are a major part of them. They are usually located in constitutive heterochromatin clusters in or near the centromeres or telomeres, and less frequently in the interstitial parts of chromosome arms. They are also frequently accumulated in sex chromosomes. The function of these clusters is to sustain the architecture of the chromosomes and the nucleus, and to regulate chromosome behavior during mitosis and meiosis. The study of satellite DNA diversity is important for understanding sex chromosome evolution, interspecific hybridization, and speciation. In this work, we identified four satellite DNA families in the genomes of two snakes from different families: Daboia russelii (Viperidae) and Pantherophis guttatus (Colubridae) and determine their chromosomal localization. We found that one family is localized in the centromeres of both species, whereas the others form clusters in certain chromosomes or subsets of chromosomes. BLAST with snake genome assemblies showed the conservation of such clusters, as well as a subtle presence of the satellites in the interspersed manner outside the clusters. Overall, our results show high conservation of satellite DNA in snakes and confirm the "library" model of satellite DNA evolution.