Scorpion Group 1 (SG1) represents a novel, highly divergent lineage of symbiotic bacteria within the class Mollicutes (phylum Mycoplasmatota). Currently, SG1’s distribution remains restricted - it has been identified exclusively within the scorpion family Vaejovidae, specifically in the genera Vaejovis and Mesomexovis. To date, SG1 has not been detected in other major scorpion families, suggesting a specialized host-symbiont relationship. In this study, we utilized the long-read capabilities of Oxford Nanopore Technology to sequence the 16S rRNA gene from the venom of two scorpion species: Paruroctonus becki (family Vaejovidae) and Anuroctonus phaiodactylus (family Anuroctonidae). We aimed to uncover cryptic microbial diversity, such as SG1, that may have been overlooked by previous short-read sequencing platforms. Our results revealed SG1 was indeed present in A. phaiodactylus but its presence was undetected in P. becki. We thus extend the host range of SG1 beyond Vaejovidae to include Anuroctonidae, refining the evolutionary boundaries of this unusual Mollicutes-scorpion association.
Rosa E. Prahl, Pratik Neupane, Angela A. Salim, Richard J. Lewis, Irina Vetter, Robert J. Capon, Glenn F. King, Volker Herzig
Scorpion venoms are natural sources of neurotoxins that primarily modulate the properties of neuronal ion channels, particularly voltage-gated sodium and potassium channels. However, they also contain a variety of small bioactive molecules that have been largely neglected in the omics era of toxinological research. In the present study, we employed a high-throughput FLIPR screen of arthropod venoms against nicotinic acetylcholine receptors (nAChRs) expressed in the human SH-SY5Y neuroblastoma cell line. The venom of the Malaysian forest scorpion Heterometrus spinifer (family: Scorpionidae) proved to be an agonist of nAChRs, and the small choline ester senecioylcholine was identified as being responsible for the observed effect. Synthetic senecioylcholine and its isomers tigloylcholine and angeloylcholine were not insecticidal when injected into sheep blowflies. Based on previous reports of senecioylcholine being toxic to vertebrates along with the agonistic effect we observed on human nAChRs, we postulate that senecioylcholine in scorpion venom is likely to assist with vertebrate prey capture and defense against vertebrate predators. Since senecioylcholine has only been previously reported in marine gastropods and moths, its presence in scorpion venom seems to represent an unusual case of convergent evolution.
Emma C. Brase, Eileen A. Hebets, Kevin B. Smith, Brandi Pessman, Heather Akin, Harley M. Boutard, Laura Segura Hernández, Marshal Hedin, Michael D. Dodd
Many people are afraid of spiders and consider them to be both dangerous and disgusting, which can negatively impact their mental well-being as well as their relationship with nature. Very few studies have examined what characteristics draw visual attention toward or away from spiders, or have assessed the impact of arachnophobia and sex on attentional biases. Here, 118 undergraduate students freely viewed single and paired images of spiders and other arthropods in their natural environments while having their eye movements monitored. Participants also completed a survey measuring spider phobia and attitudes toward spiders. Multiple eyetracking metrics (total dwell time, first run dwell time, first fixation time, and run count) were used as indicators of attentional bias. Findings suggest a general avoidance of spider images in the presence of other non-spider arthropod images as well as avoidance of scorpion images in the presence of non-scorpion arachnid images. Presentation of image pairs with two kinds of spiders elicit attention toward spider-specific features. These effects were occasionally, though not often, moderated by sex and phobia levels. Across all metrics, there was a tendency to record longer first fixation times, shorter dwell times, and lesser run counts toward images of spiders. Images of jumping spiders and insects received considerably more and faster attentional allocation relative to other spiders. Understanding how general body form versus specific spider features influence visual attention provides insight into visual factors that may motivate spider phobia, providing evidence-based knowledge that could be useful in treatments. Additionally, knowledge of potentially appealing features of spiders may provide useful perspectives for communicating the usefulness of spiders in our ecosystem.
