Soil Preference and Burrow Characteristics of Two Theraphosidae Species in Penang Island, Malaysia

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  Soil Preference and Burrow Characteristics of Two Theraphosidae Species in Penang Island, Malaysia Abstract Tarantulas play a crucial role in maintaining ecological balance by regulating insect populations. However, little is known about the soil preferences and burrow structures of tarantulas in Malaysia. This study aims to determine the soil preference as well as the burrow structure of  Coremiocnemis cunciularia  and  Chilobrachys andersoni  from Penang Island. The soil characteristics of the soil samples collected around the burrows of  Coremiocnemis cunciularia  (n = 30) and  Chilobrachys andersoni  (n = 30) were determined using soil texture analysis. The measurements and burrow structures from adults and juveniles of  Coremiocnemis cunciularia  and  Chilobrachys andersoni  were determined. It was revealed that the moisture content and clay percentage in the soil samples around burrows of  Chilobrachys anderso...

Of Seven New K+ Channel Inhibitor Peptides of Centruroides bonito, α-KTx 2.24 Has a Picomolar Affinity for Kv1.2

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Of Seven New K+ Channel Inhibitor Peptides of Centruroides bonito, α-KTx 2.24 Has a Picomolar Affinity for Kv1.2

Abstract

Seven new peptides denominated CboK1 to CboK7 were isolated from the venom of the Mexican scorpion Centruroides bonito and their primary structures were determined. The molecular weights ranged between 3760.4 Da and 4357.9 Da, containing 32 to 39 amino acid residues with three pu-tative disulfide bridges. The comparison of amino acid sequences with known potassium scorpion toxins (KTx) and phylogenetic analysis revealed that CboK1 (α-KTx 10.5) and CboK2 (α-KTx 10.6) belong to the α-KTx 10.x subfamily, whereas CboK3 (α-KTx 2.22), CboK4 (α-KTx 2.23), CboK6 (α-KTx 2.21), and CboK7 (α-KTx 2.24) bear > 95% amino acid similarity with members of the α-KTx 2.x subfamily, and CboK5 is identical to Ce3 toxin (α-KTx 2.10). Electrophysiological assays demonstrated that except CboK1, all six other peptides blocked the Kv1.2 channel with Kd values in the picomolar range (24–763 pM) and inhibited the Kv1.3 channel with comparatively less po-tency (Kd values between 20–171 nM). CboK3 and CboK4 inhibited less than 10% and CboK7 in-hibited about 42% of Kv1.1 currents at 100 nM concentration. Among all, CboK7 showed out-standing affinity for Kv1.2 (Kd = 24 pM), as well as high selectivity over Kv1.3 (850-fold) and Kv1.1 (~6000-fold). These characteristics of CboK7 may provide a framework for developing tools to treat Kv1.2-related channelopathies.

Shakeel, Kashmala, Timoteo Olamendi-Portugal, Muhammad Umair Naseem, Baltazar Becerril, Fernando Z. Zamudio, Gustavo Delgado-Prudencio, Lourival Domingos Possani, and Gyorgy Panyi. 2023. "Of Seven New K+ Channel Inhibitor Peptides of Centruroides bonito, α-KTx 2.24 Has a Picomolar Affinity for Kv1.2" Toxins 15, no. 8: 506. https://doi.org/10.3390/toxins15080506