A comparison of adhesive performance among six cursorial spider species

Posted by
  A comparison of adhesive performance among six cursorial spider species Abstract The ability to adhere to surfaces is particularly relevant for cursorial predatory arthropods like hunting spiders, which often traverse relatively complex environments characterized by large variation in substrate properties. Here, we evaluated the adhesive performance of six hunting spider species that are common in eastern temperate North America and lack specialized tarsi for climbing smooth or inclined surfaces [Lycosidae: Pardosa lapidicina Emerton, 1885 and Rabidosa rabida (Walckenaer, 1837); Oxyopidae: Oxyopes salticus Hentz, 1845; Pisauridae: Pisaurina mira (Walckenaer, 1837); Dolomedidae: Dolomedes triton (Walckenaer, 1837), and Dolomedes scriptus Hentz, 1845]. We tested adhesion performance as shear load resistance (g) on a glass plate, and as the angle of failure (°) when the plate was gradually inclined relative to horizontal. Average angle of failure and shear resistance differed among ...

Pirates of the coagulase: Clinical implications of dramatic ontogenetic shifts in Yellow Beard (Bothrops atrox) lancehead pitviper Factor Va-mediated venom activation of blood clotting factors

Posted by

 


Pirates of the coagulase: Clinical implications of dramatic ontogenetic shifts in Yellow Beard (Bothrops atrox) lancehead pitviper Factor Va-mediated venom activation of blood clotting factors

ABSTRACT

Bothrops atrox (Yellow Beard Lancehead Pitviper) is responsible for the majority of snakebite morbidity in the Amazon, yet the biochemical basis and clinical consequences of its ontogenetic venom variation remain incompletely resolved. We compared Colombian neonate and adult B. atrox venoms across plasma and fibrinogen clotting assays, thromboelastography, antivenom neutralisation, and clotting factor zymogen activation with defined cofactor conditions. Neonate venom clotting was faster on plasma, whereas adult venom showed stronger thrombin-like (pseudo-procoagulant) action on fibrinogen. All three regional antivenoms neutralised both age classes to varying degrees, with Butantan outperforming ICP and Antivipmyn-Tri. For all antivenoms, neutralisation was consistently better for adult venom. Factor-activation assays revealed activation of prothrombin and Factor VII by both age classes, with a stronger neonate signal. Prothrombin activation strictly required Factor Va as an obligate cofactor; neonate venom could generate usable FVa from FV in addition to using endogenous (thrombin-produced) FVa, while adult venom depended on endogenous FVa. Strikingly, we demonstrate Factor VII activation by B. atrox for the first time and show that FVa markedly potentiates this reaction, including FVa produced by venom cleavage of FV, with age-class differences in the efficiency of venom-produced FVa utilisation. Unlike prothrombin, the neonate venom was able to activate FVII in the absence of FVa, but at much lower levels. Metalloproteases being responsible for prothrombin activation was confirmed with the selective inhibitor prinomastat. These data resolve the mechanistic drivers of ontogenetic potency shifts and explain antivenom performance differences, with immediate implications for antivenom formulation and adjunctive inhibitor use.
Jordan, K., Champagne, P. S., Seneci, L., & Fry, B. G. (2026). Pirates of the coagulase: Clinical implications of dramatic ontogenetic shifts in Yellow Beard (Bothrops atrox) lancehead pitviper Factor Va-mediated venom activation of blood clotting factors. Toxicon, 109025. https://doi.org/10.1016/j.toxicon.2026.109025