Rational attenuation of elapid long-chain neurotoxin by targeted residue substitution and disulfide architecture simplification: implications for receptor interaction and immune recognition

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  Rational attenuation of elapid long-chain neurotoxin by targeted residue substitution and disulfide architecture simplification: implications for receptor interaction and immune recognition Abstract Elapid long-chain neurotoxins (LNTxs) exert their toxicity through high-affinity binding to nicotinic acetylcholine receptors (nAChRs). Specific residues mediate this process, including basic (Lys23, Arg33, Arg36, Lys49), structural (Cys26, Cys30), and aromatic (Phe29) amino acids. To investigate the functional and immunogenic implications of modifying these residues, we designed two recombinant variants of a consensus LNTx. The first variant, rLcNTx V1, contains charge-reversal mutations at four key basic positions, while the second, rLcNTx V2, lacks the segment corresponding to the fifth disulfide bond. We expressed both variants in Escherichia coli Origami cells. rLcNTx V1 was recovered in a soluble form, but rLcNTx V2 was present only in inclusion bodies. We assessed the binding ...

Andean giants: Priscula spiders from Ecuador, with notes on species groups and egg-sac troglomorphism (Araneae: Pholcidae)

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 Andean giants: Priscula spiders from Ecuador, with notes on species groups and egg-sac troglomorphism (Araneae: Pholcidae)


ABSTRACT

The Andean genus Priscula Simon, 1893 includes the largest Neotropical pholcid spiders, but due to their mostly cryptic lifestyle they remain poorly collected and poorly studied. Many species available in collections remain undescribed and nothing has been published about the phylogeny and the biology of the genus. Here, we deal with a recent collection of Priscula spiders from Ecuador, the country of origin of the type species, P. gularis Simon, 1893. We describe eight new species, collected at 17 localities at altitudes from 640–3160 m, all based on males and females: P. azuay sp. nov., P. llaviucu sp. nov., P. espejoi sp. nov., P. esmeraldas sp. nov., P. chapintza sp. nov., P. pastaza sp. nov., P. bonita sp. nov., and P. lumbaqui  sp. nov. We use a sample of approximately 26 species-level taxa, mostly from Ecuador and Venezuela, to propose a first hypothesis about relationships within the genus. Our data (mainly CO1) suggest the existence of five species groups, three of which are represented in Ecuador. The cave-dwelling P. pastaza sp. nov. is only slightly troglomorphic (paler than usual; anterior median eyes strongly reduced or lost) but differs dramatically from forest-dwelling congeners in its biology: it hangs fully exposed in its web during the day; it produces egg sacs with only 6–7 eggs (average in 15 other species: 42 eggs); and it produces the largest eggs relative to body size of all studied species.

Bernhard A., H., Guanliang, M., Nadine, D., Jonas, A., & Mauricio, H. (2023). Andean giants: Priscula spiders from Ecuador, with notes on species groups and egg-sac troglomorphism (Araneae: Pholcidae). European Journal of Taxonomy, 909(1), 1-63. https://doi.org/10.5852/ejt.2023.909.2351