Biochemical characterisation and substrate-specific proteolytic diversity of venom metalloproteinases in African puff adders

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  By 4028mdk09 - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=11200575 Biochemical characterisation and substrate-specific proteolytic diversity of venom metalloproteinases in African puff adders Abstract The puff adder ( Bitis arietans ) is a highly venomous viper responsible for many snakebite fatalities in Africa, yet there have been few geographically comprehensive analyses of its venom proteins, particularly of the proteases that play a key role in pathology of envenoming. To address this, we have isolated, identified and characterised the bioactivity of the venom metalloproteases of puff adders obtained from a range of localities. Prominent in all venoms was a PI snake venom metalloproteinase (SVMP), derived from a larger PII precursor. This protein existed as either non-glycosylated (21 kDa) or glycosylated, the latter containing either one (26 kDa) or two N-glycans (30 kDa). All the venoms we tested contained either one or the other form: none had...

Species traits modulate ecological release in island red devil spiders (Araneae: Dysderidae)

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Species traits modulate ecological release in island red devil spiders (Araneae: Dysderidae)

Abstract

  1. Ecological release, defined as the expansion of range, habitat and/or resource usage by an organism following a reduction in competitors, is ubiquitous in oceanic islands. Species colonising recently formed islands, whose ancestors evolved in highly competitive environments, may experience relaxed selection because of reduced diversity of not only competitors, but also predators and parasites. Indeed, factors other than competition may also be involved in determining the species' ability to expand their niche. Ecological specialisation, for instance, has been frequently considered an irreversible change, preventing the reversal to more generalist states.
  2. Here, we integrate geometric morphometric methods, stable isotope analyses and species distribution models using the spider genus Dysdera as a model organism to explore the implications of different cheliceral morphotypes related to different trophic adaptations on the species' ability to undergo ecological release.
  3. Contrary to our expectations, species with morphotypes associated with a more specialised diet tend to expand their trophic niche, increase their spatial range and modify their phenotype more similarly across the same area of morphospace when compared to generalist species.
  4. This outcome might be explained by their ability to feed on isopods, a prey typically rejected by most predators, along with other arthropods. This specialisation may have been crucial in expanding their ecological niche compared to generalist species.
  5. Our study constitutes one of the first examples of using a multidisciplinary approach to better understand the effects of ecological release on colonising species with supposed different trophic preferences.
Bellvert, A., Enguídanos, A., Pollock, L. J., Patiño, J., Kaliontzopoulou, A., & Arnedo, M. A. Species traits modulate ecological release in island red devil spiders (Araneae: Dysderidae). Insect Conservation and Diversity. https://doi.org/10.1111/icad.12841