Ontogenetic and sexual differences in the venom of Bothrops moojeni: insights from a litter and its mother.

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.

Insights on sperm assays and cryopreservation in six Neotropical pit vipers.

Breeding snakes in captivity has become more and more relevant due not only to the growing interest on their venoms but also to the increasing number of endangered species worldwide. Unfortunately, studies on the formation of germplasm banks for these reptiles do not follow the same pace, and literature on sperm cryopreservation remains in its infancy when compared to other taxa. Herein, we first validated a sperm-egg binding assay (using chicken egg perivitelline membrane - EPM) and some nonfluorescent staining techniques for semen analysis of two pit viper genera (Bothrops and Crotalus), and then we investigated the protective effects of dimethylacetamide (DMA), dimethylformamide (DMF), and dimethylsulfoxide (DMSO) at different concentrations (3, 6 and 12%) throughout the freezing process in five species of lancehead and one of rattlesnake. Our validation process showed high correlations among sperm functional tests (including sperm-binding to EPM) and motion parameters. A total of 166 fresh ejaculates were acquired from 233 collection attempts, and 63.9% of these samples exhibited minimal motility for freezing (≥20%). During cryopreservation we observed that post-thaw motility and quality was improved by higher levels of cryoprotectants (CPA), regardless the CPA type. Lower concentrations of CPA were less harmful to sperm motility and progressive motility following the equilibrium phase, but were ineffective in protecting these cells from the freeze-thaw cycle. Likewise, higher CPA concentrations increased post-thaw integrity of the acrosome and plasma membrane for most species, except for rattlesnakes in which only 12% DMSO produced better outcomes.

Histopathological Findings in the Viscera of Malformed Neotropical Viperids.

Congenital malformations (CMs) or developmental abnormalities are pathological processes defined as morphological defects that originate during embryonic stages. A wide variety of CMs is observed in reptiles, most of which are incompatible with normal life. Characterization of CMs and their pathogenesis are of great importance for the conservation of reptiles, including neotropical viperids (NVs). External CMs are often reported in these species, but little is known about concomitant microscopical findings in the viscera of malformed individuals. In order to partially fill in this gap in knowledge, we aimed to investigate and characterize histopathological findings in the viscera of malformed NVs, jararacas (Bothrops jararaca) and South American rattlesnakes (Crotalus durissus), correlating these findings with features of external CMs. From 78 malformed snakes analysed, 100% (19/19) of rattlesnakes and 98.3% (58/59) of jararacas had histopathological changes in the viscera. Liver and/or kidney fatty degeneration was the most common finding in malformed and control animals. Renal glomerulocystic and tubular disease was significantly correlated with brachygnathia (P < 0.05) in jararacas. These results add to the body of knowledge of snake pathology and demonstrate some associations between external CMs and visceral histopathological findings, some of which could have implications for individual survival.

Comparison of venoms from wild and long-term captive Bothrops atrox snakes and characterization of Batroxrhagin, the predominant class PIII metalloproteinase from the venom of this species.

Comparisons between venoms from snakes kept under captivity or collected at the natural environment are of fundamental importance in order to obtain effective antivenoms to treat human victims of snakebites. In this study, we compared composition and biological activities of Bothrops atrox venom from snakes collected at Tapajós National Forest (Pará State, Brazil) or maintained for more than 10 years under captivity at Instituto Butantan herpetarium after have been collected mostly at Maranhão State, Brazil. Venoms from captive or wild snakes were similar except for small quantitative differences detected in peaks correspondent to phospholipases A2 (PLA2), snake venom metalloproteinases (SVMP) class PI and serine proteinases (SVSP), which did not correlate with fibrinolytic and coagulant activities (induced by PI-SVMPs and SVSPs). In both pools, the major toxic component corresponded to PIII-SVMPs, which were isolated and characterized. The characterization by mass spectrometry of both samples identified peptides that matched with a single PIII-SVMP cDNA characterized by transcriptomics, named Batroxrhagin. Sequence alignments show a strong similarity between Batroxrhagin and Jararhagin (96%). Batroxrhagin samples isolated from venoms of wild or captive snakes were not pro-coagulant, but inhibited collagen-induced platelet-aggregation, and induced hemorrhage and fibrin lysis with similar doses. Results suggest that in spite of environmental differences, venom variability was detected only among the less abundant components. In opposition, the most abundant toxin, which is a PIII-SVMP related to the key effects of the venom, is structurally conserved in the venoms. This observation is relevant for explaining the efficacy of antivenoms produced with venoms from captive snakes in human accidents inflicted at distinct natural environments.

Malformations in neotropical viperids: qualitative and quantitative analysis.

Malformations can occur in all living species, but there is little information about anomalies that occur in snakes and their frequency. This study assessed malformations in newborn South American pit vipers (Bothrops jararaca) and South American rattlesnakes (Crotalus durissus) from wild captured pregnant females (240 and 35 litters, respectively). Newborn snakes were measured, weighed, sexed and studied grossly and by radiography for the presence of malformations. Ninety-five malformed pit vipers were identified from 4,087 births (2.3%), while 36 malformed rattlesnakes were found from 324 births (11.1%). Spinal abnormalities were the most common in both species, followed by fusion of ventral scales. Pit vipers showed a greater range of malformations including schistosomia (22.1%), kinked tail (13.7%), bicephaly (3.1%) and hydrocephaly (2.1%).

Circadian pattern of Bothrops moojeni in captivity (Serpentes: Viperidae)

Members of the subfamily Crotalinae are considered to be essentially nocturnal and most of the data about these snakes have been collected from the field. Information on how nutritional status affects the movement rate and activity patterns is a key point to elucidating the ecophysiology of snakes. In this study, we distributed 28 lancehead Bothrops moojeni into three groups under distinct feeding regimens after a month of fasting. Groups were divided as follows: ingestion of meals weighing (A) 40 percent, (B) 20 percent, or (C) 10 percent of the snake body mass. Groups were monitored for five days before and after food intake and the activity periods and movement rates were recorded. Our results show that B. moojeni is prevalently nocturnal, and the activity peak occurs in the first three hours of the scotophase. After feeding, a significant decrease in activity levels in groups A and B was detected. The current results corroborate previous field data that describe B. moojeni as a nocturnal species with low movement rates. The relationship between motion and the amount of food consumed by the snake may be associated with its hunting strategy.