The rise and diversification of spidroins in the deep-time evolution of spiders

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  The rise and diversification of spidroins in the deep-time evolution of spiders Summary The evolutionary success of spiders is often attributed to their stunning ability to produce and utilize silk, but the potential link between the molecular and phenotypic basis of silk production and spider diversification is seldom tested in a robust dated phylogenetic framework. Here, we provide a macroevolutionary context for testing hypotheses by reconstructing and dating the spider tree of life using genomic and transcriptomic data. We searched exhaustively for members of the spider silk protein (spidroin) gene family from omics data and identified them in an iterative phylogenetic pipeline. Four distinct new types of spidroins with atypical sequence characteristics are discovered to be widespread in true spiders with the potential to affect silk properties, as inferred by our phylogenetic generalized linear mixed model and phylogenetic generalized least squares analyses. Combining our ro...

Comparative Histological Characterization of the Venom Apparatus in Five Iranian Scorpion Species

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Comparative Histological Characterization of the Venom Apparatus in Five Iranian Scorpion Species

Abstract

Background: Scorpion envenomation represents a significant public health concern worldwide. The telson is located at the distal part of the metasoma, where venom is secreted from a pair of venom glands. The curved stinger is responsible for venom delivery.

Methods: This study conducted a histological examination of five scorpion species, including Hottentotta juliae, Hotten­totta zagrosensis, Odontobuthus kermanus, and Scorpio maurus, which were gathered from Fars Province, as well as Hemiscorpius lepturus, collected from Khuzestan Province. The telson histology was assessed using the hematoxylin-eosin method.

Results: The exocuticle, endocuticle, and secretory epithelium, which consists of secretory and supporting cells, were identified in the tissues of all species. Cuticle pores were distributed throughout the telson. Each venom gland possesses a central lumen, where secreted venom accumulates within a venom sac. The intercalated tendon is located beneath the basal membrane and connects the glandular epithelium to the cuticle. The sizes and shapes of the secretory epithelial cells vary depending on the species.

Conclusion: While histology elucidates the structural organization of scorpion venom glands, integrating histological findings with proteomic and histochemical approaches would provide a more comprehensive understanding of venom composition and interspecific variation.

Soltan-Alinejad, P., Kargar-Jahromi, H., Karimi, F., & Azizi, K. (2025). Comparative histological characterization of the venom apparatus in five Iranian scorpion species. Journal of Arthropod-Borne Diseases, 19 (2). https://doi.org/10.18502/jad.v19i2.20193