Advancing the systematics of Araneae: ultraconserved elements phylogenomics demonstrates the non-monophyly of Miturgidae Simon, 1886 and supports the Familial Rank of Systariidae Deeleman-Reinhold, 2001

Posted by
  Advancing the systematics of Araneae: ultraconserved elements phylogenomics demonstrates the non-monophyly of Miturgidae Simon, 1886 and supports the Familial Rank of Systariidae Deeleman-Reinhold, 2001 Abstract The systematic status of the family Miturgidae Simon, 1886 and related subfamilies has long been problematic, primarily due to challenges in interpreting morphological characters and limited molecular sampling. In this study, we reconstruct the phylogeny of Miturgidae using ultraconserved elements and estimate its divergence time. Our results suggest that Systariinae does not belong to Miturgidae, but rather is sister to all other families of the Dionycha B clade. Consequently, we elevate it to family rank as Systariidae Deeleman-Reinhold, 2001 and discuss its morphological synapomorphies. Furthermore, our analyses place Miturgidae as the sister clade to Viridasiidae + Selenopidae under multiple phylogenetic methods. Divergence time estimates indicate an ancient origin of...

Context makes the clot: Evolutionary and translational mismatches in snake venom thrombin-like enzyme-induced fibrin-clot formation between human and diverse animal plasmas

Posted by

 


Context makes the clot: Evolutionary and translational mismatches in snake venom thrombin-like enzyme-induced fibrin-clot formation between human and diverse animal plasmas

ABSTRACT

Snake venoms produce dynamic effects upon the blood chemistry of both prey species and human bite victims. However, comparative testing to ascertain differential coagulotoxic effects between humans and animals, and therefore the suitability of animal models to predict human effects, are scarce. To fill this knowledge gap, this study tested how pitviper with thrombin-like venoms act across vertebrate plasmas and whether animal models predict human outcomes. We evaluated Deinagkistrodon acutus, Gloydius tsushimaensis, Ovophis okinavensis, Protobothrops mangshanensis, and Trimeresurus albolabris, using thromboelastography on human, rodent, avian, and amphibian plasmas. Assays quantified initiation, kinetics, and maximal clot strength. On human plasma, all venoms were thrombin-like, acting in a pseudo-procoagulant manner to form weak fibrin clots. Clinically this would result in a net anticoagulant effect through fibrinogen depletion. However, the results on animal plasmas differed markedly. At the dose tested which produced a potent response in human plasma, none of the venoms displayed the thrombin-like activity on any animal plasma. Instead, there were a myriad of other activities suggesting destructive cleavage of fibrinogen, inhibition of clotting enzymes, and activation of clotting factor zymogens. As such, the potent thrombin-like activity on human plasma appears to be an evolutionary bioproduct, rather than one that is selected for on prey plasma. Translationally in this case, the animal models did not reliably predict the mechanistic underpinnings of human fibrinogen-depleting snakebite outcomes. This emphasises the importance of preclinical testing of venom effects to predict snakebite outcomes, should be based upon human plasma testing not animal models. These results underscore how snake venom research is fundamentally at the intersection between evolutionary biology and toxicology, with a single data set having implications for diverse, yet interlocking, fields of research. These outcomes underscore the paradigm that animal models in general are poor predictors of potential human clinical effects, and reciprocally that effects on human material are poor predictors of potential prey pathophysiological effects.
Morecroft, H., Chowdhury, A., & Fry, B. G. (2025). Context makes the clot: Evolutionary and translational mismatches in snake venom thrombin-like enzyme-induced fibrin-clot formation between human and diverse animal plasmas. Toxicon, 108584. https://doi.org/10.1016/j.toxicon.2025.108584