Seasonality in Crotalus durissus venom

Rattlesnakes belonging to the genus Crotalus are widely distributed throughout the Americas. In Brazil, symptoms commonly associated with envenomation by Crotalus durissus collilineatus include myalgia, rhabdomyolysis, renal failure, neurotoxicity, and progressive paralysis, which are related to the protein composition of this venom. Snake venom composition exhibits compositional variability that may reflect geographic distribution, age, captivity, diet, sex, and even individual genetics. Although seasonality is also considered a possible source of variation, there are few reports of such variability in snake venom. In this work, venoms of the same eight C. durissus collilineatus were extracted every three months for two years, to analyze seasonal changes in composition and activities. To this end, venom composition was analyzed by protein quantification, SDS-PAGE, and HPLC, and the LAAO, PLA2 and coagulant activities were measured. Venoms of these C. d. collilineatus showed minor seasonal differences in venom activities and no composition differences were found. LAAO and coagulant activities displayed a pattern of seasonal change, while PLA2 activity seemed to have no seasonality tendency. Also, there are sexual differences, in which males seem to be more stable than females in regard to some activities. Individual variability occurs even in seasonal variation of activities, highlighting the importance of controlling circumstances of venom extraction before comparing results between groups of snakes.

From birth to adulthood: An analysis of the Brazilian lancehead (Bothrops moojeni) venom at different life stages

The Brazilian lancehead (Bothrops moojeni) has a wide distribution in Brazil and represents a serious public health hazard. Previous works reported that the symptoms of snakebites caused by B. moojeni juveniles’ bites were mainly related to coagulation, while those caused by adults’ bites had a more prominent local damage. In this work, we analyzed the venoms of B. moojeni at different life stages to better understand the ontogeny shift in this species. Snakes were grouped by age and sex, and venom pools were formed accordingly. Compositional analyses by one-dimensional electrophoresis (1-DE), chromatography, and mass spectrometry revealed that ontogenetic changes might be mostly related to phospholipase A₂ (PLA₂) and metalloproteases. Regarding the venoms functional aspect, proteolytic, L-amino acid oxidase, PLA₂, and coagulant in vitro activities were assayed, but only the first and the last ones showed age-related changes, with the venom of snakes up to 1 year-old displaying lower proteolytic and higher coagulant activities, while those from 2 years-old onward presented the opposite relation. The venoms of 3 years-old snakes were exceptions to the compositional and functional pattern of adults as both venoms presented profiles similar to neonates. Sex-related differences were observed in specific groups and were not age-related. In vivo experiments (median lethal dose and hemorrhagic activity) were statistically similar between neonates and adults, however we verified that the adult venom killed mice faster comparing to the neonates. All venoms were mostly recognized by the antibothropic serum and displayed similar profiles to 1-DE in western blotting. In conclusion, the Brazilian lancehead venom showed ontogenetic shift in its composition and activities. Furthermore, this change occurred in snakes from 1 to 2 years-old, and interestingly the venom pools from 3 years-old snakes had particular characteristics, which highlights the importance of comprehensive studies to better understand venom variability.

Maintenance of venomous snakes in captivity for venom production at Butantan Institute from 1908 to the present: a scoping history

Maintenance of snakes at Butantan Institute started in the last century, intending to produce a different antivenom serum to reduce death caused by snakebites. Through a successful campaign coordinated by Vital Brazil, farmers sent venomous snakes to Butantan Institute by the railway lines with no cost. From 1908 to 1962, the snakes were kept in an outdoor serpentarium, where venom extraction was performed every 15 days. During this period, the snake average survival was 15 days. In 1963, the snakes were transferred to an adapted building, currently called Laboratory of Herpetology (LH), to be maintained in an intensive system. Although the periodicity of venom extraction remained the same, animal average survival increased to two months. With the severe serum crisis in 1983, the Ministry of Health financed remodeling for the three public antivenom producers, and with this support, the LH could be improved. Air conditioning and exhausting systems were installed in the rooms, besides the settlement of critical hygienic-sanitary managements to increase the welfare of snakes. In the early 1990s, snake survival was ten months. Over the years to the present day, several improvements have been made in the intensive serpentarium, as the establishment of two quarantines, feeding with thawed rodents, an interval of two months between venom extraction routines, and monitoring of snake health through laboratory tests. With these new protocols, average snake survival increased significantly, being eight years for the genus Bothrops, ten years for genus Crotalus and Lachesis, and four years for the genus Micrurus. Aiming the production of venoms of good quality, respect for good management practices is essential for the maintenance of snakes in captivity. New techniques and efficient management must always be sought to improve animal welfare, the quality of the venom produced, and the safety of those working directly with the venomous snakes.

Paratelmatobius mantiqueira Pombal amp; Haddad, 1999 (Anura: Leptodactylidae): New specimens and rectification of the type locality of a rare species from the Serra da Mantiqueira, southeastern Brazil

There are currently seven species of small frogs (up to 30 mm in snout-vent length) in the genus Paratelmatobius Lutz Carvalho 1958 (Frost, 2020). They are all endemic to mountain ranges in the Atlantic Forest, occurring in the Serra do Mar and Serra da Mantiqueira, southeastern Brazil (Santos et al. 2019). Most congeneric species are considered rare and their distribution is restricted to small areas (Domenico et al. 2014; Santos et al. 2020). Paratelmatobius mantiqueira Pombal Haddad 1999 is one of the most enigmatic species in the genus. It hadn't been seen from 1953, when the type series was collected, until 2005, when one specimen was found in the municipality of Resende, state of Rio de Janeiro (Vrcibradic et al. 2010). Recently, we found a new population of P. mantiqueira in the state of São Paulo. While reviewing the scattered information available about the species, we noticed inconsistencies related to the species' type locality. We propose its rectification in this manuscript.

The Role of Feeding Specialization on Post-Prandial Metabolic Rate in Snakes of the Genus Bothrops

Feeding specialization is a recurrent issue in the evolution of snakes and is sometimes associated to morphological and/or behavioral adaptations that improve snake performance to exploit a particular food type. Despite its importance for animal fitness, the role of physiological traits has been much less studied than morphological and behavioral traits in the evolution of feeding specialization in snakes. In this context, the energetic cost of post-prandial period is an important physiological factor due to the remarkable effect on the snake energy budget. We collected data on post-prandial metabolic rate (SDA) in five species of pit vipers from the genus Bothrops with different degrees of mammal feeding specialization to test the hypothesis that feeding specialist species have lower energy costs during the digestion of their regular food item when compared to species with a more generalist diet. Our results support this hypothesis and suggest that ontogenetic changes in diet can be accompanied by changes in energy cost of the digestion process.

Phylogenetic analysis of standard metabolic rate of snakes: a new proposal for the understanding of interspecific variation in feeding behavior

The current proposal about the variation of standard metabolic rates (SMR) in snakes predicts that SMR is influenced by the feeding frequency (frequent or infrequent feeders). However, feeding frequency in snakes is poorly studied and hard to quantify under natural conditions. Alternatively, foraging strategy was studied for a large number of species and is usually related to the feeding frequency. In this work, we performed a meta-analysis on the SMR of compiled data from 74 species of snakes obtained from the literature and five more different species of lanceheads (genus Bothrops), after categorization according to the foraging mode (ambush or active foraging) and regarding their phylogenetic history. We tested the hypothesis that foraging mode (FM) is a determinant factor on the interspecific variation of SMR despite the phylogenetic relationship among species. We demonstrated that FM predicted SMR, but there is also a partial phylogenetic structuration of SMR in snakes. We also detected that evolution rates of SMR in active foragers seem to be higher than ambush-hunting snakes. We suggested that foraging mode has a major effect over the evolution of SMR in snakes, which could represent an ecophysiological co-adaptation, since ambush hunters (with low feeding rates) present a lower maintenance energetic cost (SMR) when compared to active foragers. The higher SMR evolution rates for active foraging snakes could be related to a higher heterogeny in the degree of activity during hunting by active foragers when compared to ambush-hunting snakes.

PARÂMETROS ELETROCARDIOGRÁFICOS DE CASCAVÉIS (Crotalus durissus, Linnaeus, 1758) EM CATIVEIRO

            Apesar de a eletrocardiografia ser vastamente empregada na clínica veterinária, esta ferramenta ainda é pouco utilizada no diagnóstico de patologias em serpentes. Este trabalho teve como objetivo a caracterização dos parâmetros eletrocardiográficos da espécie Crotalus durissus em cativeiro, sob condições controladas.  Para isto, 23 serpentes foram submetidas ao exame eletrocardiográfico, aonde os seguintes parâmetros foram analisados: a freqüência cardíaca, ritmo, eixo cardíaco, ondas P e T, complexo QRS, assim como os intervalos P-R e S-T nas derivações cardíacas DI, DII, DIII, Avf, Avl e Avr. Os resultados demonstraram que a técnica foi eficiente nas mensurações das deflexões cardíacas, porém a análise da freqüência e ritmo geralmente é prejudicada devido a um viés estresse-induzido e sua interpretação deve ser cautelosa. Os parâmetros eletrocardiográficos de Crotalus durissus determinados neste trabalho foram bastante consistentes e com mínimas variações, o que parece possibilitar sua utilização no diagnóstico das doenças cardíacas em serpentes. A escassez de padrões eletrocardiográficos em serpentes torna muito difícil a comparação e a interpretação de como as variáveis morfológicas, fisiológicas e ecológicas podem influenciar os parâmetros eletrocardiográficos, por este motivo, novas pesquisas que determinem os padrões eletrocardiográficos de diferentes espécies serão absolutamente necessárias para o uso do eletrocardiograma como ferramenta diagnóstica na rotina clínica.