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...

Insights Into Spatial Orientation and Cognition in Tarantulas (Araneae: Theraphosidae) Under Natural Conditions, With Notes on Possible Ontogenetic Niche Shifts

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Insights Into Spatial Orientation and Cognition in Tarantulas (Araneae: Theraphosidae) Under Natural Conditions, With Notes on Possible Ontogenetic Niche Shifts

ABSTRACT

Research on cognition in spiders, particularly in relation to navigation, has primarily focused on araneomorphs studied under controlled conditions. Mygalomorphs, such as tarantulas (Theraphosidae), have been largely neglected and almost nothing is known about their cognitive foraging behaviour in natural environments. Here, we present nine observations of arboreal and fossorial New World tarantulas, including a blind cave-dwelling species, which together provide rare field-based evidence that tarantulas may be capable of flexible, experience-based navigation. All observed arboreal species, as well as two fossorial species, exhibited behaviour that may reflect spatial learning, by foraging in prey-rich locations situated relatively far from their retreats. This behaviour differs from ontogenetic shifts in habitat use, which are noted here in several species for comparison; possible ontogenetic shifts in foraging behaviour in troglobitic tarantulas are also briefly discussed. The remaining observations involve tarantulas responding to disturbance with fast, direct returns to their burrows without disorientation. We discuss the likely allothetic and idiothetic cues underlying these behaviours, while also considering alternative or complementary explanations for retreat recognition and foraging movements based on chemical and chemo-tactile cues. Finally, we briefly review existing experimental research on tarantula cognition, as well as studies on physiological and behavioural changes associated with stress or altered internal states that may interact with cognitive processes.

Zamani, A., & West, R. C. (2026). Insights Into Spatial Orientation and Cognition in Tarantulas (Araneae: Theraphosidae) Under Natural Conditions, With Notes on Possible Ontogenetic Niche Shifts. Ecology and Evolution, 16(4), e73329. https://doi.org/10.1002/ece3.73329