Sex Role–Dependent Behavioral and Architectural Divergence in a Jumping Spider

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  Sex Role–Dependent Behavioral and Architectural Divergence in a Jumping Spider ABSTRACT Sex differences in behavior and functional traits are often attributed to differences in mating effort intensity, but the role of sex-specific parental demands remains poorly understood. Using the jumping spider Toxeus maxillosus —where males engage in mate searching and courtship without providing parental care, while females provide extended maternal care from egg attendance to offspring maturity (around 3 months)—we conducted an exploratory investigation into whether these distinct selective pressures led to divergence in spatial behaviors and nest architecture. Results revealed that males and females showed equivalent accuracy, latency, and learning-related performance in both a route-planning test under water stress and a color-pattern associative memory task. In contrast, during nest-construction assays, females built complex, multi-entrance structures that closely matched the container'...

In vivo biodistribution of Loxosceles intermedia venom in animal models with different pathological outcomes

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In vivo biodistribution of Loxosceles intermedia venom in animal models with different pathological outcomes

Abstract

Spiders of the Loxosceles spp. genus have a wide geographic distribution and are among the main causes of arachnidism in Brazil. Despite advances in venom characterization, fundamental aspects such as its in vivo kinetics and biodistribution remain little understood. This study aimed to investigate the biodistribution of Loxosceles intermedia spider venom through radiolabeling with technetium-99 metastable (99ᵐTc). Radiolabeling efficiency was evaluated using paper chromatography and C18 column, and effectiveness was assessed by SDS-PAGE. Biological activity after radiolabeling was verified through an in vitro sphingomyelinase activity assay and by evaluating dermonecrotic and edematogenic effects in rabbits. The results showed that most venom proteins were efficiently radiolabeled and that the venom remained biologically active after radiolabeling, allowing its distribution to be tracked in mice and rabbits. In both models, the venom concentrated at the injection site and was predominantly biodistributed to the kidneys and bladder. These findings are relevant given the distinct pathophysiological profiles of the animal models used. This is the first study to evaluate, in real time and in live animals, the biodistribution of L. intermedia venom through radiolabeling, and it may provide valuable data for understanding its mechanisms of action and improved the diagnostic of loxoscelism.
Da Silva Moreira, R., Pires, L. O., Cardoso Cunha, L., Fiorini de Carvalho, I. A., Chávez-Olórtegui, C., Minozzo, J. C., Rocha, M. N., Cardoso, V. N., Antunes Fernandes, S. O., & Felicori, L. F. (2025). In vivo biodistribution of Loxosceles intermedia venom in animal models with different pathological outcomes. Toxicon, 108619. https://doi.org/10.1016/j.toxicon.2025.108619