Armed stem to stinger: a review of the ecological roles of scorpion weapons

Identification, classification, and characterization of alpha and beta subunits of LVP1 protein from the venom gland of four Iranian scorpion species

Scorpion venoms contain bioactive peptides and proteins. Some, can be used for pharmaceutical purposes. So, identification of venom proteins matters because, in addition to determining the function of the toxins can also be an excellent guide to developing new drugs. Here, we got transcriptome of venom glands from four Iranian scorpion species, including Hemsicorpius lepturus, Mesobuthus eupeus, Andructunus crassicuada, and Hottentotta saulcyi using cDNA library synthesis and high-throughput transcriptomic analysis of the venom glands. In a comparative way, we identified the cDNA encoding isoforms of subunits (alpha and beta) of BotLVP1/BmLVP1-like protein in the venom gland of three species except for H. lepturus. Characterization and structure determination of the LVP1_like proteins combined with gene map analysis provided evidence of the existence of some isoforms of LVP1_like proteins, encoded by genes with two exons and one intron, which can be classified in CSαβ superfamily in the venom gland of three Iranian scorpion species. According to the high similarity with BotLVP1 and BmLVP1, these proteins could also be potent to mediate cholesterol homeostasis. However, further research is needed to prove it, and this study just may lay the foundation lead to light up this way.

Behavioural Indicators of Pain and Suffering in Arthropods and Might Pain Bite Back?

Pain in response to tissue damage functions to change behaviour so that further damage is minimised whereas healing and survival are promoted. This paper focuses on the behavioural criteria that match the function to ask if pain is likely in the main taxa of arthropods. There is evidence consistent with the idea of pain in crustaceans, insects and, to a lesser extent, spiders. There is little evidence of pain in millipedes, centipedes, scorpions, and horseshoe crabs but there have been few investigations of these groups. Alternative approaches in the study of pain are explored and it is suggested that studies on traumatic mating, agonistic interactions, and defensive venoms might provide clues about pain. The evolution of high cognitive ability, sensory systems, and flexible decision-making is discussed as well as how these might influence the evolution of pain-like states.

The effect of structural curvature on the load-bearing characteristics of biomechanical elements

Miniature, sharped-edge, curved-shape biomechanical elements appear in various biological systems and grant them diverse functional capabilities, such as mechanical defense, venom injection, and frictional support. While these biomechanical elements demonstrate diverse curved shapes that span from slightly curved needle-like elements (e.g., stingers), through moderately curved anchor-like elements (e.g., claws), to highly curved hook-like elements (e.g., fangs)-the curvature effect on the load-bearing capabilities of these biomechanical elements are yet mostly unknown. Here, we employ structural-mechanical modeling to explore the relationships between the curved shapes of biomechanical elements on their local deformation mechanisms, overall elastic stiffness, and reaction forces on a target surface. We found that the curvature of the biomechanical element is a prime modulator of its load-bearing characteristics that substantially affect its functional capabilities. Slightly curved elements are preferable for penetration states with optimal load-bearing capabilities parallel to their tips but possess high directional sensitivity and degraded capabilities for scratching states; contrary, highly curved elements are suitable for combined penetration-scratching states with mild directional sensitivity and optimal load-bearing capabilities in specialized angular orientation to their tips. These structural-mechanical principles are tightly linked to the intrinsic functional roles of biomechanical elements in diverse natural systems, and their synthetic realizations may promote new engineering designs of advanced biomedical injections, functional surfaces, and micromechanical devices.

The Enzymatic Core of Scorpion Venoms

Enzymes are an integral part of animal venoms. Unlike snakes, in which enzymes play a primary role in envenomation, in scorpions, their function appears to be ancillary in most species. Due to this, studies on the diversity of scorpion venom components have focused primarily on the peptides responsible for envenomation (toxins) and a few others (e.g., antimicrobials), while enzymes have been overlooked. In this work, a comprehensive study on enzyme diversity in scorpion venoms was performed by transcriptomic and proteomic techniques. Enzymes of 63 different EC types were found, belonging to 330 orthogroups. Of them, 24 ECs conform the scorpion venom enzymatic core, since they were determined to be present in all the studied scorpion species. Transferases and lyases are reported for the first time. Novel enzymes, which can play different roles in the venom, including direct toxicity, as venom spreading factors, activators of venom components, venom preservatives, or in prey pre-digestion, were described and annotated. The expression profile for transcripts coding for venom enzymes was analyzed, and shown to be similar among the studied species, while being significantly different from their expression pattern outside the telson.

Reevaluating scorpion ecomorphs using a naïve approach

Background

Ecomorphs create the opportunity to investigate ecological adaptation because they encompass organisms that evolved characteristic morphologies under similar ecological demands. For over 50 years, scorpions have been empirically assigned to ecomorphs based on the characteristic morphologies that rock, sand, vegetation, underground, and surface dwellers assume. This study aims to independently test the existence of scorpion ecomorphs by quantifying the association between their morphology and ecology across 61 species, representing 14 families of the Scorpiones order.

Results

Without a priori categorization of species into ecomorphs, we identified four groups based on microhabitat descriptors, which reflect how scorpion ecospace is clustered. Moreover, these microhabitat groups, i.e., ecotypes, have significantly divergent morphologies; therefore, they represent ecomorphs. These ecomorphs largely correspond with the ones previously described in the literature. Therefore, we retained the names Lithophilous, Psammophilous, and Pelophilous, and proposed the name Phytophilous for vegetation dwellers. Finally, we sought to map the morphology-ecology association in scorpions and found that the morphological regions most tightly associated with ecology are at the extremities. Moreover, the major trend in ecomorphological covariation is that longer walking legs and relatively slender pedipalps (pincers) are associated with sandy microhabitats, while the inverse morphological proportions are associated with rocky microhabitats.

Conclusions

Scorpion ecomorphs are validated in a naïve approach, from ecological descriptors and whole body anatomy. This places them on a more solid quantitative footing for future studies of ecological adaptation in scorpions. Our results verify most of the previously defined ecomorphotypes and could be used as a current practice to understand the adaptive significance of ecological morphology.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12862-022-01968-0.