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The multiscale structure of biomaterials enables their exceptional mechanical robustness, yet the impact of each constituent at their relevant length scale remains elusive. We used SAXD analysis to expose the intact chitin-fiber architecture within the exoskeleton on a scorpion's claw, revealing varying orientations, including Bouligand and unidirectional regions different from other arthropod species. We uncovered the contribution of individual components' constituent behavior to its mechanical properties from the micro- to the nanoscale. At the microscale, in-situ micromechanical experiments were used to determine site-specific stiffness, strength, and failure of the biocomposite due to fiber orientation, while metal-crosslinking of proteins is characterized via fluorescence maps. At the constituent level, combined with FEA simulations, we uncovered the behavior of fiber-matrix deformation with fiber diameter <53.7 nm and protein modulus in the range 1.4–11 MPa. The unveiled microstructure-mechanics relationship sheds light on the evolved structural functionalities and constituents' interactions within the scorpion cuticle. The pincer exoskeleton is a fundamental part of the scorpion's body due to its multifunctionality. Precise structural and compositional analysis within the hierarchy is paramount to understand the fundamentals of the mechanical properties of the composite exoskeleton. Here, we expose the intact chitin-fiber architecture of the pincer exoskeleton using nondestructive analysis. In-situ mechanical characterization was performed at nanometer levels within the exoskeleton hierarchy, which complemented with simulations, uncovered the elastic modulus of the protein matrix. Our findings confirm the presence and distribution of metal ions and their role as reinforcements in the protein matrix via ligand coordinate bonds. In future work, these findings can be of great potential to inspire the design of composite materials. [Display omitted] [ABSTRACT FROM AUTHOR]

• A mechanical sensing platform with a bio-inspired rigid-flexible coupling structure was proposed. • The sensing platform possesses excellent robustness, high positioning accuracy and rapid response time. • The bioinspired sensing platform accurately identifies dynamic and static loads simultaneously. • The prepared platform effectively detects the magnitude, motion trajectory, location and loading speed of spatial forces. • The proposed sensing platform can be mass-produced and highly integrated into various detecting systems. Three-dimensional force sensors play a crucial role in the aerospace industry and precision mechanical manufacturing. However, the current sensors still lack sufficient stability in the sensing of spatial mechanical forces and struggle to distinguish dynamic and static pressure signals. Coincidentally, scorpions in nature show a remarkable capacity to perceive three-dimensional stress with exceptional stability and sensitivity. This is primarily attributed to the highly sensitive sensing structure and stable multilayer structure in the slit sensilla of a scorpion. Inspired by this design, we develop a biomimetic sensing platform capable of accurately detecting the magnitude, position, and loading rate of a spatial force. This bionic system consists of an alternating combination of carbon fiber board (CFB) and hydroxylated multiwalled carbon nanotubes-styrene–isoprene (HMCNSI). Specifically, the flexible HMCNSI polymer enhances fatigue resistance, while the rigid CFB offers support and protection, resulting in exceptional robustness and stability of the sensing platform. The platform exhibits a rapid response time (14 ms), a fast recovery time (28 ms), and excellent sensitivity (GF = 46 for strain 0–3 %; GF = 118.3 for strain 3–6 %). Furthermore, the mechanical sensing platform can distinguish dynamic and static loads, identify exertion force rates in the range of 0.1–1 m/s and force magnitudes within 30 N, and provide a high positioning accuracy of 1 mm. The proposed biomimetic sensing platform exhibits promising applications in the field of precision detection of spatial forces such as human-machine interactions and intelligent robotics. [ABSTRACT FROM AUTHOR]

Lactuca serriola is a well-known plant in the El kalaa of Sraghna region that occupies an important place in traditional medicine for its alleged effectiveness against the venom of scorpions and snakes. This work aims to study the neutralizing capacity of Lactuca serriola extracts on scorpion Buthus atlantis venom by histological and biochemical analyses. In this study we test for the first time, the anti-venom activity of Lactuca serriola against Buthus atlantis venom by fixing the dose of venom at LD 99 , while the dose of the extract was variable (0.5, 2 g/kg). Histological changes in vital organs as well as biochemical changes in mice were recorded. The quantification and qualification of polyphenols were performed by High Performance Liquid phase Chromatography (HPLC). The results showed that the LD 50 of Buthus atlantis venom subcutaneously is 0.4 mg/kg, and the methanolic extract of the plant Lactuca serriola at the dose of 2 g/kg administered orally had a 66.66% protective capacity. Based on the results of the histological and biochemical study, the effect of the venom revealed tissue damage and enzyme imbalance, whereas the administration of the plant extract showed restoration of lesions in the different tissues, and a counteraction of the serum enzyme imbalance. HPLC analysis of the polyphenols revealed the presence of chlorogenic acid, sorbic acid, coumaric acid and quercetin. The present study supports the traditional use of Lactuca serriola as anti-venom and the potential for natural product drug discovery. • Acute toxicity for Buthus atlantis scorpion venom may be classified as a highly toxic substance worldwide. • The richness of Lactuca serriola plant extract in phenolic compounds was deduced from the phytochemical screening and HPLC analysis. • The induction of envenomation by subcutaneous injection of an LD99 is manifested by histological and biochemical alterations in the main vital organs. [ABSTRACT FROM AUTHOR]

Since scorpions exist almost all over the world, some expected body differences exist among the species: undoubtedly, the most evident is the shape and size of their pincers or chelae. The scorpion chela is a multifunctional body component (e.g. attack/defense, mating and protection from the environment) that leads to the development of different stresses in the cuticle. How such stresses in the cuticle are accommodated by different chelae shape and size is largely unknown. Here we provide new comparative data on the hierarchical structure and mechanical properties of the chela cuticle in two scorpion species: Scorpio Maurus Palmatus (SP) that has a large chela and Buthus Occitanus Israelis (BO), with a slender chela. We found that the SP exocuticle is composed of four different sublayers whereas the BO exocuticle displays only two sublayers. These structures are different from the exocuticle morphologies in crustaceans, where the Bouligand morphology is present throughout the entire layer. Moreover, the scorpion chela cuticle presents an exclusive structural layer made of unidirectional fibers arranged vertically towards the normal direction of the cuticle. Nanoindentation measurements were performed under dry conditions on transversal and longitudinal planes to evaluate the stiffness and hardness of the different chela cuticle layers in both scorpions. The chela cuticle structure is a key factor towards the decision of the scorpion whether to choose to sting or use the chela for other mechanical functions. Many arthropods such as lobsters, crabs, stomatopods, isopods, and spiders have been the subject of research in recent years, and their hierarchical structure and mechanical properties extensively investigated. Yet, except for a limited number of pre-1980 publications, comparatively little work has been devoted to the terrestrial scorpion. The scorpion chela is a multifunctional part of the body (e.g. attack/defense, mating and protection from the environment) that involves the development of various stresses in the cuticle. How these stresses in the chela cuticle are managed by different chelae shape and size is still unknown. The lack of a single study that integrates morphological characterization of the entire hierarchical structure of the scorpion chela cuticle, and local mechanical properties, significantly affects the scientific knowledge regarding important structural approaches that can be used by nature to maximize functionality. [ABSTRACT FROM AUTHOR]

Scorpion toxins can kill other animals by inducing paralysis and arrhythmia, which limits the potential applications of these agents in the clinical management of diseases. Antitumor-analgesic peptide (AGAP), purified from Buthus martensii Karsch, has been proved to possess analgesic and antitumor activities. Trp38, a conserved aromatic residue of AGAP, might play an important role in mediating AGAP activities according to the sequence and homology-modeling analyses. Therefore, an AGAP mutant, W38G, was generated, and effects of both AGAP and the mutant W38G were examined by whole-cell patch clamp techniques on the sodium channels hNav1.4 and hNav1.5, which were closely associated with the biotoxicity of skeletal and cardiac muscles, respectively. The data showed that both W38G and AGAP inhibited the peak currents of hNav1.4 and hNav1.5; however, W38G induced a much weaker inhibition of both channels than AGAP. Accordingly, W38G exhibited much less toxic effect on both skeletal and cardiac muscles than AGAP in vivo. The analgesic activity of W38G and AGAP were verified in vivo as well, and W38G retained analgesic activity similar to AGAP. Inhibition to both Nav1.7 and Nav1.8 was involved in the analgesic mechanism of AGAP and W38G. These findings indicated that Trp38 was a key amino acid involved in the biotoxicity of AGAP, and the AGAP mutant W38G might be a safer alternative for clinical application because it retains the analgesic efficacy with less toxicity to skeletal and cardiac muscles. [ABSTRACT FROM AUTHOR]

Objective: Scorpionism is an endemic public health problem in Jordan encountered by health providers in all parts of the country. This study updates epidemiological data on scorpion sting encounters in Jordan.Methods: Data on scorpion sting encounters were obtained from government and military hospitals around the country, and the National Drug and Poison Information Center (NDPIC). P values and 95% confidence intervals (CIs) were calculated using SPSS Professional Statistics Package version 22 (IBM Corp., Armonk, NY) program.Results: Epidemiological data on 1205 scorpion sting cases reported between 2006 and 2012 are reported. Male to female ratio was 1.18:1, aged 23.3±16 (mean±SD) and 26.4±16.9 years for males and females, respectively. Age groups between 1 to 20 years old constituted 44.6% of the total sting encounters, while adults aged >30 years constituted 30%. Scorpion sting encounters peaked in July (22.5%) and August (23%), with the lowest numbers of recorded cases in February and January (1.6 and 1.9%, respectively). Scorpion stings occurred mostly outdoors (66%). Medical complications associated with scorpion sting cases included fever, difficulty in breathing, drowsiness and dizziness, and numbness, while severe complications include respiratory failure and tachycardia. Hospitalization required 1 to 3 days among admitted patients with no fatalities.Conclusions: Scorpion stings remain a medical problem in Jordan that requires more attention by health providers. Reporting of scorpion sting cases should be enforced from all healthcare centers throughout the country to better understand the epidemiology and health implications of human encounters. [ABSTRACT FROM AUTHOR]

• We have assembled 8 new scorpion mitogenomes from transcriptomic datasets, annotated and described them in detail. We duplicated the number of scorpion mitogenomes available at NCBI. • We performed a comparative analysis and confirmed the differential synteny of the family Buthidae with respect to other scorpions. • The family Buthidae invariably showed differential patterns in the molecular characteristics of mitogenomes with respect to other scorpions. Scorpions are a group of arachnids with great evolutionary success that comprise more than 2,000 described species. Mitochondrial genomes have been little studied in this clade. We describe and compare different scorpion mitochondrial genomes and analyze their architecture and molecular characteristics. We assembled eight new scorpion mitochondrial genomes from transcriptomic datasets, annotated them, predicted the secondary structures of tRNAs, and compared the nucleotide composition, codon usage, and relative synonymous codon usage of 16 complete scorpion mitochondrial genomes. Lastly, we provided a phylogeny based on all mitochondrial protein coding genes. We characterized the mitogenomes in detail and reported particularities such as dissimilar synteny in the family Buthidae compared to other scorpions, unusual tRNA secondary structures, and unconventional start and stop codons in all scorpions. Our comparative analysis revealed that scorpion mitochondrial genomes exhibit different architectures and features depending on taxonomic identity. We highlight the parvorder Buthida, particularly the family Buthidae, as it invariably exhibited different mitogenome features such as synteny, codon usage, and AT-skew compared to the parvorder Iurida that included the rest of the scorpion families we analyzed in this study. Our results provide a better understanding of the evolution of mitogenome features and phylogenetic relationships in scorpions. [ABSTRACT FROM AUTHOR]

• The PI/AgNPs aerogels with structural strength, light, and flexible were prepared. • The SPM provided structural strength while providing recovery and contact points. • The SPM-interface secondary response was used to achieve wide electrical response. • The PI/AgNPs sensors showed good conductivity response consistency at 25 ℃ and 250 ℃. The demand for sensitive pressure sensors is increasing due to the rapid development of intelligent electronic equipment in high-tech fields such as aerospace and transportation. However, the high-temperature conditions encountered in aerospace applications pose challenges to the performance of flexible sensing materials used in related equipment. In this context, silver nanoparticles (AgNPs)-wrapped polyimide (PI) hybrid aerogels (PI/AgNPs aerogels) with scorpion pectine-like microstructures (SPM) were fabricated by freeze-drying the precursor solution, followed by a thermal imidization reaction and a dipping process with a AgNPs solution. The SPM grew vertically on the layered structure with a height between 20 and 40 μm. These PI/AgNPs provided sufficient structural strength as a support while providing recovery and contact points. The AgNPs were uniformly dispersed on the SPM (with a thickness of 78–120 nm on PI/AgNPs-1). The SPM-interface secondary response structure was used to realize an electrical response in a broad tension (the PI/AgNPs-2 aerogel has changed from −15.63 kPa under 30 % tensile stress to 69.25 kPa under 70 % compression stress). The hybrid aerogels had excellent sensing performance, including good resistance change (89 %), ultra-high sensitivity (6.9 kPa−1), the ability to detect different deformations (compression, tension, and bending), and low fatigue after 3000 load-unload cycles. In addition, these aerogels were able to withstand high temperatures up to 250 °C, and they showed good conductivity response consistency at high and room temperatures. These PI/AgNPs aerogels can be used as sensors in extreme conditions such as in aeroengine peripheral electronics for sensing and detecting external loads. [ABSTRACT FROM AUTHOR]

In this study, we characterized the distribution of microsatellites in the genomes and genes of Centruroides exilicauda and Mesobuthus martensii , carried out Gene Ontology (GO) analysis and GO enrichment analysis of coding sequences (CDSs) with microsatellite (SSR). In addition, over-represented GO functions related to environmental interactions, development process and methylation were identified to develop functional markers and facilitate further analysis of microsatellite function in the genes of scorpions. Location analysis indicated that microsatellites were predominantly concentrated at both ends of genes. Most genes containing microsatellite had the SSR present at only one locus, from which we infer that the number of SSRs per gene is limited even though intragenic tandem repeats can generate functional variability. Lastly, we identified 75 SSRs in 64 genes of 54 expanded gene families and 1 SSR in the toxin gene of Mesobuthus martensii , allowing future studies on the effect of microsatellites on gene function. [ABSTRACT FROM AUTHOR]

Objective: Scorpion stings are registered worldwide, but the incidence and the features of the envenomations vary depending on the region. The aim of this review was to summarize the epidemiological, clinical, diagnostic, and therapeutic data worldwide regarding humans stung by scorpions.Methods: A systematic review of the literature was conducted through the online databases of the Virtual Health Library (VHL), which hosts Medline and the Latin American and Caribbean Center on Health Sciences Informational (LILACS) database. We selected articles published between January 1, 2002 and July 31, 2014.Results: Scorpion envenomation reports were found throughout the world, mainly in subtropical and tropical regions. The clinical manifestations were sympathetically and parasympathetically mediated, depending on the species of scorpion. Some of the most common severe complications of scorpionism included respiratory distress syndrome, pulmonary edema, cardiac dysfunction, impaired hemostasis, pancreatitis, and multiple organ failure. Scorpion envenomation could be classified as mild, moderate, and severe, and the therapeutic approach was based on the case severity. The treatment comprised 3 components: symptomatic measures, vital functions support, and injection of antivenom. Moreover, the time that elapsed between the sting and administration of the appropriate medical care was extremely important to the patient's prognosis.Conclusions: The large number of scorpion stings worldwide is concerning and reaffirms the need for new prevention measures and policies to reduce the incidence, prevalence, morbidity, and mortality rates from these poisonous arachnids. [ABSTRACT FROM AUTHOR]

In this study the antimicrobial activity of low molecular weight (3.22 kDa) chitosan, obtained for the first time from a species belonging to the Scorpiones, was screened against nine pathogenic microorganisms (seven bacteria and two yeasts) and compared with that of medium molecular weight commercial chitosan (MMWCC). It was observed that the antimicrobial activity of the low molecular weight scorpion chitosan (LMWSC) was specific to bacterial species in general rather than gram-negative or gram-positive bacterial groups. It was also determined that LMWSC had a stronger inhibitory effect than the MMWCC, particularly on the bacterium Listeria monocytogenes and the yeast Candida albicans , which are important pathogens for public health. In addition, it was recorded that the MMWCC had a greater inhibitory effect on Bacillus subtilis than LMWSC. According to the results obtained by the disc diffusion method, the antibacterial activity of both LMWSC and MMWCC against B. subtilis and Salmonella enteritidis was higher than the widely used antibiotic Gentamicin (CN, 10 μg/disc). [ABSTRACT FROM AUTHOR]

The lesser Asian scorpion Mesobuthus eupeus (Buthidae) is one of the most widely spread and dispersed species of the Mesobuthus genus, and its venom is actively studied. Nevertheless, a considerable amount of active compounds is still under-investigated due to the high complexity of this venom. Here, we report a comprehensive analysis of putative potassium channel toxins (KTxs) from the cDNA library of M. eupeus venom glands, and we compare the deduced KTx structures with peptides purified from the venom. For the transcriptome analysis, we used conventional tools as well as a search for structural motifs characteristic of scorpion venom components in the form of regular expressions. We found 59 candidate KTxs distributed in 30 subfamilies and presenting the cysteine-stabilized α/β and inhibitor cystine knot types of fold. M. eupeus venom was then separated to individual components by multistage chromatography. A facile fluorescent system based on the expression of the KcsA-Kv1.1 hybrid channels in Escherichia coli and utilization of a labeled scorpion toxin was elaborated and applied to follow Kv1.1 pore binding activity during venom separation. As a result, eight high affinity Kv1.1 channel blockers were identified, including five novel peptides, which extend the panel of potential pharmacologically important Kv1 ligands. Activity of the new peptides against rat Kv1.1 channel was confirmed (IC50 in the range of 1-780 nM) by the two-electrode voltage clamp technique using a standard Xenopus oocyte system. Our integrated approach is of general utility and efficiency to mine natural venoms for KTxs. [ABSTRACT FROM AUTHOR]

The Yellow-legged hornet (Vespa velutina nigrithorax), native to regions of Southeast Asia, was accidentally introduced in Europe, South Korea, and Japan, where is has often become invasive. Due to its potential negative impacts at ecologic, economic and social levels, this hornet was included in the "Union list" of the EU legislation for invasive alien species. This means that measures are urgently needed to prevent further introductions, as well as to early-detect and control spread to avoid new populations. In this study we aim to identify the main reported drivers of distribution, ecological preferences, impacts, and methods for preventing introduction, controlling, and managing this invasive species. The supporting information was obtained from a comprehensive literature search. Then, a literature review was performed to classify the records gathered and to extract the relevant information following an adapted Drivers-Pressures-State-Impacts-Responses framework. The achieved results show a growing interest of researchers on V. velutina nigrithorax through time due to its quick spread and impacts on new ecosystems. They also revealed that there is much information on the State of invasions, whereas more knowledge is needed regarding the Drivers of those invasions. Biological traits such as life history traits, morphology, and the sting venom properties are some of the most studied topics regarding V. velutina nigrithorax. In the future, research should focus on the topics that lack information, analyse other Response solutions that meet the intended measures by the EU legislation, and use new methodology to study the impacts caused by this invader under new perspectives. [ABSTRACT FROM AUTHOR]

Two insect-specific scorpion toxins, BjαIT and AahIT were produced as alkali-soluble protein inclusions in Escherichia coli. The inclusion bodies themselves exhibited no toxicity against Culex pipiens larvae. However, coadministration with Cry4Aa toxin enhanced the mosquitocidal activity by 2–3 fold. Insect-specific scorpion toxins can be good supplements for Cry toxin-based bioinsecticides. [Copyright &y& Elsevier]

To gain success in the evolutionary "arms race," venomous animals such as scorpions produce diverse neurotoxins selected to hit targets in the nervous system of prey. Scorpion α-toxins affect insect and/or mammalian voltage-gated sodium channels (Navs) and thereby modify the excitability of muscle and nerve cells. Although more than 100α-toxins are known and a number of them have been studied into detail, the molecular mechanism of their interaction with Navs is still poorly understood. Here, we employ extensive molecular dynamics simulations and spatial mapping of hydrophobic/hydrophilic properties distributed over the molecular surface ofα-toxins. It is revealed that despite the small size and relatively rigid structure, these toxins possess modular organization from structural, functional, and evolutionary perspectives. The more conserved and rigid "core module" is supplemented with the "specificity module" (SM) that is comparatively flexible and variable and determines the taxon (mammal versus insect) specificity of α-toxin activity. We further show that SMs in mammal toxins are more flexible and hydrophilic than in insect toxins. Concomitant sequence-based analysis of the extracellular loops of Navs suggests thatα-toxins recognize the channels using both modules. We propose that the core module binds to the voltage-sensing domain IV, whereas the more versatileSMinteracts with the pore domain in repeat I of Navs. These findings corroborate and expand the hypothesis on different functional epitopes of toxins that has been reported previously. In effect, we propose that the modular structure in toxins evolved to match the domain architecture of Navs. [ABSTRACT FROM AUTHOR]

We report the case of a 2-year-old Bedouin boy in whom developed severe and unusual complications after being stung, most probably, by the yellow scorpion Leiurus quinquestriatus hebraeus. Five hours after arrival to the emergency department, the boy had multisystem organ failure involving the central nervous system (seizure activity followed by coma with dilated, nonreactive pupils, and severe brain edema), shock (noncardiogenic), disseminated intravascular coagulation, renal failure, hepatic failure, and watery diarrhea, causing his death. In view of the relevant literature, we discuss the pathophysiologic events ultimately leading to his death. [ABSTRACT FROM AUTHOR]

Abstract: The study of internal clock systems of scorpions in weightless conditions is the goal of the SCORPI experiment. SCORPI was selected for flight on the International Space Station (ISS) and will be mounted in the European facility BIOLAB, the European Space Agency (ESA) laboratory designed to support biological experiments on micro-organisms, cells, tissue, cultures, small plants and small invertebrates. This paper outlines the main features of a breadboard designed and developed in order to allow the analysis of critical aspects of the experiment. It is a complete tool to simulate the experiment mission on ground and it can be customised, adapted and tuned to the scientific requirements. The paper introduces the SCORPI-T experiment which represents an important precursor for the success of the SCORPI on BIOLAB. The capabilities of the hardware developed show its potential use for future similar experiments in space. [Copyright &y& Elsevier]

Animal toxins are associated with well defined selectivity profiles; however the molecular basis for this property is not understood. To address this issue we refined our previous three-dimensional models of the complex between the sea anemone toxin BgK and the S5-S6 region of Kvl.1 (Gilquin, B., Racape, J., Wrisch, A., Visan, V., Lecoq, A., Grissmer, S., Ménez, A., and Gasparini, S. (2002) J. Biol. Chem. 277, 37406-37413) using a docking procedure that scores and ranks the structures by comparing experimental and back-calculated values of coupling free energies ΔΔGint obtained from double-mutant cycles. These models further highlight the interaction between residue 379 of Kv1.1 and the conserved dyad tyrosine residue of BgK. Because the nature of the residue at position 379 varies from one channel subtype to another, we explored how these natural mutations influence the sensitivity of Kv1 channel subtypes to BgK using binding and electrophysiology experiments. We demonstrated that mutations at this single position indeed suffice to abolish or enhance the sensitivity of Kv1 channels for BgK and other sea anemone and scorpion toxins. Altogether, our data suggest that the residue at position 379 of Kv1 channels controls the affinity of a number of blocking toxins. [ABSTRACT FROM AUTHOR]

Maurocalcine (MCa) is a 33-amino-acid residue peptide toxin isolated from the scorpion Scorpio maurus palmatus. External application of MCa to cultured myotubes is known to produce Ca2+ release from intracellular stores. MCa binds directly to the skeletal muscle isoform of the ryanodine receptor, an intracellular channel target of the endoplasmic reticulum, and induces long lasting channel openings in a mode of smaller conductance. Here we investigated the way MCa proceeds to cress biological membranes to reach its target. A biotinylated derivative of MCa was produced (MCab) and complexed with a fluorescent indicator (streptavidine-cyanine 3) to follow the cell penetration of the toxin. The toxin complex efficiently penetrated into various cell types without requiring metabolic energy (low temperature) or implicating an endocytosis mechanism. MCa appeared to share the same features as the so-called cell-penetrating peptides. Our results provide evidence that MCa has the ability to act as a molecular carrier and to cress cell membranes in a rapid manner (1–2 min), making this toxin the first demonstrated example of a scorpion toxin that translocates into cells. [ABSTRACT FROM AUTHOR]

Scorpion β-toxins that affect the activation of mammalian voltage-gated sodium channels (Navs) have been studied extensively, but little is known about their functional surface and mode of interaction with the channel receptor. To enable a molecular approach to this question, we have established a successful expression system for the anti-mammalian scorpion β-toxin, Css4, whose effects on rat brain Nays have been well characterized. A recombinant toxin, His-Css4, was obtained when fused to a His tag and a thrombin cleavage site and had similar binding affinity for and effect on Na currents of rat brain sodium channels as those of the native toxin isolated from the scorpion venom. Molecular dissection of His-Css4 elucidated a functional surface of 1245 Ų composed of the following: 1) a cluster of residues associated with the α-helix, which includes a putative "hot spot" (this cluster is conserved among scorpion β-toxins and contains their "pharmacophore"); 2) a hydrophobic cluster associated mainly with the β2 and β3 strands, which is likely to confer the specificity for mammalian Navs; 3) a single bioactive residue (Trp-58) in the C-tail; and 4) a negatively charged residue (Glu-15) involved in voltage sensor trapping as inferred from our ability to uncouple toxin binding from activity upon its substitution. This study expands our understanding about the mode of action of scorpion β-toxins and illuminates differences in the functional surfaces that may dictate their specificities for mammalian versus insect sodium channels. [ABSTRACT FROM AUTHOR]

Buthotus judaicus toxin 1 (BjTx-1) and toxin 2 (BjTx-2), two novel peptide activators of ryanodine receptors (RyR), were purified from the venom of the scorpion B.judaicus. Their amino acid sequences differ only in 1 residue out of 28 (residue 16 corresponds to Lys in BjTx-1 and Ile in BjTx-2). Despite a slight difference in EC50, both toxins increased binding of [³H]ryanodine to skeletal sarcoplasmic reticulum at micromolar concentrations but had no effect on cardiac or liver microsomes. Their activating effect was Ca2+-dependent and was synergized by caffeine. B. judaicus toxins also in- creased binding of [³H]ryanodine to the purified RyR1, suggesting that a direct protein-protein interaction mediates the effect of the peptides. BjTx-1 and BjTx-2 induced Ca2+ release from Ca2+-loaded sarcoplasmic reticulum vesicles in a dose-dependent manner and induced the appearance of long lived subconductance states in skeletal RyRs reconstituted into lipid bilayers. Three-dimensional structural modeling reveals that a cluster of positively charged residues (Lys11 to Lys16) is a prominent structural motif of both toxins. A similar structural motif is believed to be important for activation of RyRs by imperatoxin A (IpTxa), another RyR-activating peptide (Gurrola, G. B., Arevalo, C., Sreekumar, R., Lokuta, A. J., Walker, J. W., and Valdivia, H. H. (1999) J. Biol. Chem. 274, 7879–7886). Thus, it is likely that B. judaicus toxins and imperatoxin A bind to RyRs by means of electrostatic interactions that lead to massive conformational changes in the channel protein. The different affinity and structural diversity of this family of scorpion peptides makes them excellent peptide probes to identify RyR domains that trigger the channel to open. [ABSTRACT FROM AUTHOR]

Three homologous acidic peptides have been isolated from the venom of three different Parabuthus scorpion species, P. transvaalicus, P. villosus, and P. granulatus. Analysis of the primary sequences reveals that they structurally belong to subfamily 11 of short chain α-K[sup +]blocking peptides (Tytgat, J., Chandy, K. G., Garcia, M. L., Gutman, G. A., Martin-Eauclaire, M. F., van der Walt, J. J., and Possani, L. D. (1999) Trends Pharmacol. Sci. 20, 444-447). These toxins are 36-37 amino acids in length and have six aligned cysteine residues, but they differ substantially from the other α-K[sup +] toxins because of the absence of the critical Lys27 and their total overall negative charge. Parabutoxin 1 (PBTx1), which has been expressed by recombinant methods, has been submitted to functional characterization. Despite the lack of the Lys[sup 27], this toxin blocks several Kv1-type channels heterologously expressed in Xenopus oocytes but with low affinities (micromolar range). Because a relationship between the biological activity and the acidic residue substitutions may exist, we set out to elucidate the relative impact of the acidic character of the toxin and the lack of the critical Lys[sup 27] on the weak activity of PBTx1 toward Kv1 channels. To achieve this, a specific mutant named rPBTx1 T24F/V26K was made recombinantly and fully characterized on Kv1-type channels heterologously expressed in Xenopus oocytes. Analysis of rPBTx1 T24FN26K displaying an affinity toward Kv1.2 and Kv1.3 channels in the nanomolar range shows the importance of the functional dyad above the acidic character of this toxin. [ABSTRACT FROM AUTHOR]

Describes how tetrapandins, a new class of scorpion toxins inhibit store-operated calcium entry in human embryonic kidney-293 cells. Chemical inhibitors; Mass spectrometry analysis; Liquid chromatography.

Presents a study suggesting that critical amino acid residues determine the binding affinity and the Ca[sup 2+] release efficacy of maurocalcine in skeletal muscle cells. Background on maurocalcine, a 33 amino acid residue peptide toxin isolated from the scorpion Scorpio maurus palmatus; Chemical synthesis of the toxin and its mutated analogues; Interaction with the skeletal muscle ryanodine receptor.

• FA levels are used to evaluate the impact of urbanization in the scorpion Bothirurus bonariensis. • The FA levels show a significant increased according to the increase of urbanization over the years. • Different types of traits are differentially affected by the environmental stress. • FA can be useful to evaluate the effects of environmental stress on invertebrate populations. • Stenotopic scorpions are a good model for studying the anthropogenic impact on natural ecosystems. Urbanization causes the loss of large amounts of habitat and produces significant changes in environmental conditions with consequences in the individual's behavior, morphology, and physiology in natural populations. The urbanization can impact in the individual's development instability (DI) that may be measured with the fluctuating asymmetry (FA) level making it an environmental quality bioindicator. In addition, the FA of each trait should be interpreted considering the trait functional importance, morphogenesis and history of selection pressures. In this paper, we evaluated the impact of two decades of increasing urbanization levels over a population of the pampean scorpion Bothriurus bonariensis. We analyze the FA level in somatic and genital traits in adult individuals of both sexes, collected every ~ 10 years (1997, 2008, 2018). Interestingly, in this study the somatic traits (pedipalp chelae) would be under directional selection and are shaped throughout the individual's growth. In contrast, the genital traits (male's hemispermatophore) are involved in the sperm transfer process and could be under stabilizing selection. Also, hemispermatophores are affected for less time by environmental stressors since they are formed once the individual has reached sexual maturity. Our results showed a significant increase in the FA levels in somatic traits of males and females, according to the increase of urbanization along years. In contrast, genital traits showed no changes in the level of FA in females, and only a few male genital traits presented an increase in the FA level. This work shows evidence that the measured scorpion traits (under different selective pressures and morphogenesis) might present differences in their susceptibility to environmental stress. We discuss these results in a context of DI of individuals caused by urbanization. We support the idea that the level of FA can be useful as an index to evaluate the effects of environmental stress on invertebrate populations. Furthermore, our paper presents the scorpions as a good model that could be used as an indicator group for studying the impact of the anthropogenic disturbance factors on natural ecosystems. [ABSTRACT FROM AUTHOR]