Comparación del efecto neuromuscular del veneno de las serpientes coral micrurus dissoleucus y micrurus mipartitus

Los venenos de serpientes de coral (genero Micrurus) han sido reportados por tener un amplio espectro de actividades farmacológicas que incluyen acciones pre y/o postsinapticas así como también miotóxica. Mientras algunos estudios han investigado los efectos humanos potenciales, la actividad de neurotóxica de venenos de serpientes coral ha sido poco investigada en términos de relaciones ecológicas y evolutivas entre el grupo. El propósito de este estudio fue investigar los efectos fisiológicos en la neurotransmisión del veneno de las especial altamente relacionadas filogenéticamente Micrurus dissoleucus que habita principalmente en regiones séricas a semiáridas y Micrurus mipartitus la cual habita en una gran variedad de hábitats que incluyen bosque montano bajo y bosque nublado. El efecto in vitro del veneno fue examinado utilizando la preparación de musculo cervical digastrico de pollo. El veneno de M. mipartitus causo una inhibición dosis dependiente de las contracciones evocadas al nervio (0,1 Hz, 0,2 ms, Voltaje supramaximo), e inhibió significativamente la respuesta apreciablemente a la acetilcolina exógena, indicando la presencia de neurotóxinas postsinapticas. La adición de Neostigmina (5 mM) no revirtió la inhibición causada por este veneno (10?Êg/ml). El veneno de M. dissoleucus (3.50 ?Êg/ml) parece ser miotóxico indicado por la falta de inhibición a las contracciones evocadas al nervio (0,1 Hz, 0,2 ms, Voltaje supramaximo), el aumento significativo en la tensión de línea de base (3 y10 ?Êg/ml) y la inhibición de la respuesta al KCl. La inhibición de fosfolipasa A2, reemplazando Ca2+ (2,5 mM) en la solución fisiológica por Sr2+ (10 MM) atenuó la inhibición de contracciones indirectas, indicando la participación de PLA2 en la acción miotóxica del veneno. Los resultados demuestran las diferencias presentes en el veneno de especies altamente relacionadas filogeneticamente y sugieren una diversidad hasta ahora insospechada de acciones farmacológicas en un solo linaje, que tiene implicaciones en el manejo clínico de los envenenamientos y brinda una luz adicional acerca de las fuerzas que conducen la evolución de veneno.Biólogo (a)Pregrad

Domain loss facilitates accelerated evolution and neofunctionalization of duplicate snake venom metalloproteinase toxin genes.

Gene duplication is a key mechanism for the adaptive evolution and neofunctionalization of gene families. Large multi-gene families often exhibit complex evolutionary histories as a result of frequent gene duplication acting in concordance with positive selection pressures. Alterations in the domain structure of genes, causing changes in the molecular scaffold of proteins, can also result in a complex evolutionary history and has been observed in functionally diverse multi-gene toxin families. Here, we investigate the role alterations in domain structure have on the tempo of evolution and neofunctionalization of multi-gene families using the snake venom metalloproteinases (SVMPs) as a model system. Our results reveal that the evolutionary history of viperid (Serpentes: Viperidae) SVMPs is repeatedly punctuated by domain loss, with the single loss of the cysteine-rich domain, facilitating the formation of P-II class SVMPs, occurring prior to the convergent loss of the disintegrin domain to form multiple P-I SVMP structures. Notably, the majority of phylogenetic branches where domain loss was inferred to have occurred exhibited highly significant evidence of positive selection in surface-exposed amino acid residues, resulting in the neofunctionalization of P-II and P-I SVMP classes. These results provide a valuable insight into the mechanisms by which complex gene families evolve and detail how the loss of domain structures can catalyse the accelerated evolution of novel gene paralogues. The ensuing generation of differing molecular scaffolds encoded by the same multi-gene family facilitates gene neofunctionalization, whilst presenting an evolutionary advantage through the retention of multiple genes capable of encoding functionally distinct proteins

Primaerenergieverbrauch in der Bundesrepublik Deutschland 1. Halbjahr 1990/1991

SIGLECopy held by FIZ Karlsruhe; available from UB/TIB Hannover / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Estimating snakebite incidence from mathematical models: A test in Costa Rica.

BackgroundSnakebite envenoming is a neglected public health challenge that affects mostly economically deprived communities who inhabit tropical regions. In these regions, snakebite incidence data is not always reliable, and access to health care is scare and heterogeneous. Thus, addressing the problem of snakebite effectively requires an understanding of how spatial heterogeneity in snakebite is associated with human demographics and snakes' distribution. Here, we use a mathematical model to address the determinants of spatial heterogeneity in snakebite and we estimate snakebite incidence in a tropical country such as Costa Rica.Methods and findingsWe combined a mathematical model that follows the law of mass action, where the incidence is proportional to the exposed human population and the venomous snake population, with a spatiotemporal dataset of snakebite incidence (Data from year 1990 to 2007 for 193 districts) in Costa Rica. This country harbors one of the most dangerous venomous snakes, which is the Terciopelo (Bothrops asper, Garman, 1884). We estimated B. asper distribution using a maximum entropy algorithm, and its abundance was estimated based on field data. Then, the model was adjusted to the data using a lineal regression with the reported incidence. We found a significant positive correlation (R2 = 0.66, p-value ConclusionsOur model underscores the importance of the synergistic effect of exposed population size and snake abundance on snakebite incidence. By combining information from venomous snakes' natural history with census data from rural populations, we were able to estimate snakebite incidence in Costa Rica. The model was able to fit the incidence data at fine administrative scale (district level), which is fundamental for the implementation and planning of management strategies oriented to reduce snakebite burden

The Origin and Evolution of Metalloproteinases in the Venom of Snakes

Background: Snake venom metalloproteinases (SVMPs) are a pathologically-important, often major, toxin component of snake venoms, particularly in the venoms of viperid snakes. The SVMPs are members of the large multi-locus adamalysin gene family alongside ADAM (a disintegrin and metalloproteinase) and ADAMTS (ADAM with thrombospondin motifs) proteins. Here we discuss the evolution of SVMPs from: (i) their single ancestral recruitment into the venom of advanced snakes, to (ii) the diverse structural and functional isoforms observed in venom today. Methods: Phylogenetic analyses were used to reconstruct the evolutionary history of the adamlysins, with a focus on the SVMPs. Subsequently, the mode and tempo of SVMP evolution was analysed using ancestral sequence reconstructions, positive selection tests and macromolecular structure modeling. Results and Discussion: The ancestral recruitment of SVMPs into venom resulted from the duplication of an ADAM28-like gene. Consequently, basal SVMPs are most closely related to reptilian ADAM28 and mammalian ADAM28, ADAM7 and ADAM decysin-1 proteins. Notably, ancestral SVMPs exhibit complete conservation of cysteine residues with their non-venom ADAM homologs, demonstrating that the gain and loss of cysteine residues thought to be important for facilitating structural changes/post-translational modifications are the direct result of mutations following the recruitment of SVMPs into venom. Following this recruitment event, novel SVMP domain scaffolds have been generated in viperid snakes (P-II and P-I classes) through the duplication of SVMP genes coupled with the action of positive selection. P-III SVMPs first evolved into the P-II structure through the single evolutionary loss of the cysteine-rich domain, whilst multiple independent losses of the P-II disintegrin domain have resulted in convergent evolution of P-I SVMPs. In both instances of domain loss, adaptive evolution is a major driving force – positive selection was found to predominately act on amino acid residues predicted to be surface-exposed on the molecular surface of new SVMP scaffolds. Conclusions: These results highlight how changes to the genetic structure of venom toxins can catalyze the accelerated evolution of novel proteins and facilitate major structural and functional alterations. The generation of different molecular scaffolds (P-I, P-II and P-III SVMPs) encoded by the same multi-locus gene family appears to facilitate protein neofunctionalization, whilst also presenting an evolutionary advantage through the retention of multiple genes capable of encoding functionally distinct proteins

PIII_PII

Sequence alignment (.fas) of translated PIII and PII SVMPs used for tests of adaptive molecular evolution in the manuscrip

PII_PI

Sequence alignment (.fas) of translated PII and PI SVMPs used for tests of adaptive molecular evolution in the manuscrip

Standard Quality Characteristics and Efficacy of a New Third-Generation Antivenom Developed in Colombia Covering <i>Micrurus</i> spp. Venoms

In Colombia, Micrurus snakebites are classified as severe according to the national clinical care guidelines and must be treated with specific antivenoms. Unfortunately, these types of antivenoms are scarce in certain areas of the country and are currently reported as an unavailable vital medicine. To address this issue, La Universidad de Antioquia, through its spin-off Tech Life Saving, is leading a project to develop third-generation polyvalent freeze-dried antivenom. The goal is to ensure access to this therapy, especially in rural and dispersed areas. This project aims to evaluate the physicochemical and preclinical parameters (standard quality characteristics) of a lab-scale anti-elapid antivenom batch. The antivenom is challenged against the venoms of several Micrurus species, including M. mipartitus, M. dumerilii, M. ancoralis, M. dissoleucus, M. lemniscatus, M. medemi, M. spixii, M. surinamensis, and M. isozonus, following the standard quality characteristics set by the World Health Organization (WHO). The antivenom demonstrates an appearance consistent with standards, 100% solubility within 4 min and 25 s, an extractable volume of 10.39 mL, a pH of 6.04, an albumin concentration of 0.377 mg/mL (equivalent to 1.22% of total protein), and a protein concentration of 30.97 mg/mL. Importantly, it maintains full integrity of its F(ab′)2 fragments and exhibits purity over 98.5%. Furthermore, in mice toxicity evaluations, doses up to 15 mg/mouse show no toxic effects. The antivenom also demonstrates a significant recognition pattern against Micrurus venoms rich in phospholipase A2 (PLA2) content, as observed in M. dumerilii, M. dissoleucus, and M. isozonus. The effective dose 50 (ED50) indicates that a single vial (10 mL) can neutralize 2.33 mg of M. mipartitus venom and 3.99 mg of M. dumerilii venom. This new anti-elapid third-generation polyvalent and freeze-dried antivenom meets the physicochemical parameters set by the WHO and the regulators in Colombia. It demonstrates significant efficacy in neutralizing the venom of the most epidemiologically important Micrurus species in Colombia. Additionally, it recognizes seven other species of Micrurus venom with a higher affinity for venoms exhibiting PLA2 toxins. Fulfilling these parameters represents the first step toward proposing a new pharmacological alternative for treating snakebites in Colombia, particularly in dispersed rural areas, given that this antivenom is formulated as a freeze-dried product

The Toxicogenomic Multiverse: Convergent Recruitment of Proteins Into Animal Venoms

Throughout evolution, numerous proteins have been convergently recruited into the venoms of various animals, including centipedes, cephalopods, cone snails, fish, insects (several independent venom systems), platypus, scorpions, shrews, spiders, toxicoferan reptiles (lizards and snakes), and sea anemones. The protein scaffolds utilized convergently have included AVIT/colipase/prokineticin, CAP, chitinase, cystatin, defensins, hyaluronidase, Kunitz, lectin, lipocalin, natriuretic peptide, peptidase S1, phospholipase A2, sphingomyelinase D, and SPRY. Many of these same venom protein types have also been convergently recruited for use in the hematophagous gland secretions of invertebrates (e.g., fleas, leeches, kissing bugs, mosquitoes, and ticks) and vertebrates (e.g., vampire bats). Here, we discuss a number of overarching structural, functional, and evolutionary generalities of the protein families from which these toxins have been frequently recruited and propose a revised and expanded working definition for venom. Given the large number of striking similarities between the protein compositions of conventional venoms and hematophagous secretions, we argue that the latter should also fall under the same definition