The Primary Duct of Bothrops jararaca Glandular Apparatus Secretes Toxins

Abstract

Despite numerous studies concerning morphology and venom production and secretion in the main venom gland (and some data on the accessory gland) of the venom glandular apparatus of Viperidae snakes, the primary duct has been overlooked. We characterized the primary duct of the Bothrops jararaca snake by morphological analysis, immunohistochemistry and proteomics. The duct has a pseudostratified epithelium with secretory columnar cells with vesicles of various electrondensities, as well as mitochondria-rich, dark, basal, and horizontal cells. Morphological analysis, at different periods after venom extraction, showed that the primary duct has a long cycle of synthesis and secretion, as do the main venom and accessory glands; however, the duct has a mixed mode venom storage, both in the lumen and in secretory vesicles. Mouse anti-B. jararaca venom serum strongly stained the primary duct’s epithelium. Subsequent proteomic analysis revealed the synthesis of venom toxins—mainly C-type lectin/C-type lectin-like proteins. We propose that the primary duct’s toxin synthesis products complement the final venom bolus. Finally, we hypothesize that the primary duct and the accessory gland (components of the venom glandular apparatus) are part of the evolutionary path from a salivary gland towards the main venom gland.

Morphological Analysis Reveals a Compartmentalized Duct in the Venom Apparatus of the Wasp Spider (Argiope bruennichi)

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“…In case of the established snake venom gland organoids, the utilization of a mammalian growth factor cocktail seemingly allows a virtual indefinite culturing ( Post et al, 2020 ). The compartmentalized nature of venom systems, in which distinct areas produce different components of the venom, are also maintained in venom gland organoids ( Tayo et al, 2010 ; Hu et al, 2011 ; Undheim et al, 2014 ; Valente et al, 2018 ; Post et al, 2020 ; Schmidtberg et al, 2021 ). Furthermore, given that organoids faithfully produce venom components, they can be used to culture venom glands from animals that are difficult to study even by venomics, to obtain larger amounts of venom for functional analysis.…”