Transcriptome analysis of scorpion species belonging to the Vaejovis genus

Molecular diversity assessed by MALDI mass spectrometry of two scorpion species venom from two different locations in Morocco

Scorpion venom is a cocktail of molecules whose composition is remarkably plastic, controlled by several factors. The Moroccan scorpion fauna is characterized by its richness and high rate of endemism and the venom molecular variability of many species is not yet well characterized. The aim of the present study was to highlight the molecular variability of the venom composition of Androctonus amoreuxi and Buthacus stockmanni (endemic species), both belonging to the Buthidae family, collected from two Moroccan regions, Zagora and Tan-tan. Characterization of the molecular mass fingerprints (MFPs) of each specimen was performed by Matrix-assisted laser desorption ionization-mass spectrometry (MALDI-MS) using a sandwich (Sand) and a dried-droplet (DD) sample preparation and dilutions. Considering these two methods, a total of 828 ion signals were detected, and Sand method produced more adducts (56%) than DD (44%). We observed interspecific variations in the venom composition between these two species showing they share 235 ion signals, while 226 and 367 are specific for these two species, respectively. Moreover, B. stockmanni specimens showed a clear difference in their MFPs between the two geographical areas studied, suggesting intraspecific variations. Moreover, specimens from each population also show an intraspecific variability. In addition, for the same individual, a variation in the venom composition was also recorded depending on the milking frequency. Our results confirmed the presence of characteristic components in each extracted venom sample. In conclusion, MFPs assessed by MALDI-MS represent a fast, non-supervised, sensitive, reliable and cost-efficient approach for taxonomic identification and molecular variability characterization. This study undoubtedly represents a step forward for understanding the scorpion venom plasticity, intra/inter variations, and their temporal and geographical variability.

Varying Modes of Selection Among Toxin Families in the Venoms of the Giant Desert Hairy Scorpions (Hadrurus)

Venoms are primarily believed to evolve under strong diversifying selection resulting from persistent coevolution between predator and prey. Recent research has challenged this hypothesis, proposing that venoms from younger venomous lineages (e.g., snakes and cone snails) are governed predominantly by diversifying selection, while venoms from older venomous lineages (e.g., centipedes, scorpions, and spiders) are under stronger purifying selection. However, most research in older lineages has tested selection at more diverse phylogenetic scales. Although these tests are important for evaluating broad macroevolutionary trends underlying venom evolution, they are less equipped to detect species-level evolutionary trends, which likely have large impacts on venom variation seen at more diverse phylogenetic scales. To test for selection among closely related species from an older venomous lineage, we generated high-throughput venom-gland transcriptomes and venom proteomes for four populations of Giant Desert Hairy Scorpions (Hadrurus), including three Hadrurus arizonensis populations and one Hadrurus spadix population. We detected significant episodic and pervasive diversifying selection across a highly abundant toxin family that likely has a major role in venom function ([Formula: see text]KTxs), providing a contrast to the stronger purifying selection identified from other studies on scorpion venoms. Conversely, we detected weak episodic diversifying and/or stronger purifying selection in four toxin families (non-disulfide bridged peptides, phospholipase A2s, scorpine-like antimicrobial peptides, and serine proteases), most of which were less abundant and likely have ancillary functional roles. Finally, although we detected several major toxin families at disproportionate transcriptomic and/or proteomic abundances, we did not identify significant sex-based variation in Hadrurus venoms.

Comparative Proteomic Analysis of the Venoms from the Most Dangerous Scorpions in Morocco: Androctonus mauritanicus and Buthus occitanus

Morocco is known to harbor two of the world's most dangerous scorpion species: the black Androctonus mauritanicus (Am) and the yellow Buthus occitanus (Bo), responsible for 83% and 14% of severe envenomation cases, respectively. Scorpion venom is a mixture of biological molecules of variable structures and activities, most of which are proteins of low molecular weights referred to as toxins. In addition to toxins, scorpion venoms also contain biogenic amines, polyamines, and enzymes. With the aim of investigating the composition of the Am and Bo venoms, we conducted an analysis of the venoms by mass spectrometry (ESI-MS) after separation by reversed-phase HPLC chromatography. Results from a total of 19 fractions obtained for the Am venom versus 22 fractions for the Bo venom allowed the identification of approximately 410 and 252 molecular masses, respectively. In both venoms, the most abundant toxins were found to range between 2-5 kDa and 6-8 kDa. This proteomic analysis not only allowed the drawing of an extensive mass fingerprint of the Androctonus mauritanicus and Buthus occitanus venoms but also provided a better insight into the nature of their toxins.

The remarkably enzyme-rich venom of the Big Bend Scorpion (Diplocentrus whitei)

Scorpion venoms have long been studied for their peptide discovery potential, with modern high-throughput venom-characterization techniques paving the way for the discovery of thousands of novel putative toxins. Research into these toxins has provided insight into the pathology and treatment of human diseases, even resulting in the development of one compound with Food and Drug Administration (FDA) approval. Although most of this research has focused on the toxins of scorpion species considered medically significant to humans, the venom of harmless scorpion species possess toxins that are homologous to those from medically significant species, indicating that harmless scorpion venoms may also serve as valuable sources of novel peptide variants. Furthermore, as harmless scorpions represent a vast majority of scorpion species diversity, and therefore venom toxin diversity, venoms from these species likely contain entirely new toxin classes. We sequenced the venom-gland transcriptome and venom proteome of two male Big Bend scorpions (Diplocentrus whitei), providing the first high-throughput venom characterization for a member of this genus. We identified a total of 82 toxins in the venom of D. whitei, 25 of which were identified in both the transcriptome and proteome, and 57 of which were only identified in the transcriptome. Furthermore, we identified a unique, enzyme-rich venom dominated by serine proteases and the first arylsulfatase B toxins identified in scorpions.

The divergent genome of Scorpion Group 1 (SG1) intracellular bacterium from the venom glands of Vaejovis smithi (Scorpiones: Vaejovidae)

Scorpions were among the first animals on land around 430 million years ago. Like many arachnids, scorpions have evolved complex venoms used to paralyze their prey and for self-defense. Here we sequenced and analyzed the metagenomic DNA from venom glands from Vaejovis smithi scorpions. A metagenome-assembled genome (MAG) of 624,025 bp was obtained corresponding to the previously reported Scorpion Group 1 (SG1). The SG1 genome from venom glands had a low GC content (25.8%) characteristic of reduced genomes, many hypothetical genes and genes from the reported minimal set of bacterial genes. Phylogenomic reconstructions placed the uncultured SG1 distant from other reported bacteria constituting a taxonomic novelty. By PCR we detected SG1 in all tested venom glands from 30 independent individuals. Microscopically, we observed SG1 inside epithelial cells from the venom glands using FISH and its presence in scorpion embryos suggested that SG1 is transferred from mother to offspring.

Differential venom gland gene expression analysis of juvenile and adult scorpions Androctonus crassicauda

BACKGROUND

The Androctonus crassicauda, belonging to the genus Androctonus of the family Buthidae, is the most venomous scorpion in Middle East countries. However, the venom gland transcriptome profile of A. crassicauda scorpion has not yet been studied. In this study, we elucidated and compared the venom gland gene expression profiles of adult and juvenile male scorpion A. crassicauda using high-throughput transcriptome sequencing. This is the first report of transcriptional analysis of the venom glands of scorpions in different growth stages, with insights into the identification of the key genes during venom gland development.

RESULTS

A total of 209,951 mRNA transcripts were identified from total RNA-seq data, of which 963 transcripts were differentially expressed (DE) in adult and juvenile scorpions (p < 0.01). Overall, we identified 558 up-regulated and 405 down-regulated transcripts in the adult compared to the juvenile scorpions, of which 397 and 269 unique unigenes were annotated, respectively. GO and KEGG enrichment analyses indicated that the metabolic, thermogenesis, cytoskeleton, estrogen signaling, GnRH signaling, growth hormone signaling, and melanogenesis pathways were affected by two different growth conditions and the results suggested that the DE genes related to those pathways are important genes associated with scorpion venom gland development, in which they may be important in future studies, including Chs, Elovl, MYH, RDX, ACTN, VCL, PIP5K, PP1C, FGFR, GNAS, EGFR, CREB, CoA, PLCB, CALM, CACNA, PKA and CAMK genes.

CONCLUSIONS

These findings broadened our knowledge of the differences between adult and juvenile scorpion venom and opened new perspectives on the application of comparative transcriptome analysis to identify the special key genes.

sVmKTx, a transcriptome analysis-based synthetic peptide analogue of Vm24, inhibits Kv1.3 channels of human T cells with improved selectivity

Kv1.3 K⁺ channels play a central role in the regulation of T cell activation and Ca²⁺ signaling under physiological and pathophysiological conditions. Peptide toxins targeting Kv1.3 have a significant therapeutic potential in the treatment of autoimmune diseases; thus, the discovery of new toxins is highly motivated. Based on the transcriptome analysis of the venom gland of V. mexicanus smithi a novel synthetic peptide, sVmKTx was generated, containing 36 amino acid residues. sVmKTx shows high sequence similarity to Vm24, a previously characterized peptide from the same species, but contains a Glu at position 32 as opposed to Lys32 in Vm24. Vm24 inhibits Kv1.3 with high affinity (K_d = 2.9 pM). However, it has limited selectivity (~1,500-fold) for Kv1.3 over hKv1.2, hKCa3.1, and mKv1.1. sVmKTx displays reduced Kv1.3 affinity (K_d = 770 pM) but increased selectivity for Kv1.3 over hKv1.2 (~9,000-fold) as compared to Vm24, other channels tested in the panel (hKCa3.1, hKv1.1, hKv1.4, hKv1.5, rKv2.1, hKv11.1, hKCa1.1, hNav1.5) were practically insensitive to the toxin at 2.5 μM. Molecular dynamics simulations showed that introduction of a Glu instead of Lys at position 32 led to a decreased structural fluctuation of the N-terminal segment of sVmKTx, which may explain its increased selectivity for Kv1.3. sVmKTx at 100 nM concentration decreased the expression level of the Ca²⁺ -dependent T cell activation marker, CD40 ligand. The high affinity block of Kv1.3 and increased selectivity over the natural peptide makes sVmKTx a potential candidate for Kv1.3 blockade-mediated treatment of autoimmune diseases.

A non-lethal method for studying scorpion venom gland transcriptomes, with a review of potentially suitable taxa to which it can be applied

Scorpion venoms are mixtures of proteins, peptides and small molecular compounds with high specificity for ion channels and are therefore considered to be promising candidates in the venoms-to-drugs pipeline. Transcriptomes are important tools for studying the composition and expression of scorpion venom. Unfortunately, studying the venom gland transcriptome traditionally requires sacrificing the animal and therefore is always a single snapshot in time. This paper describes a new way of generating a scorpion venom gland transcriptome without sacrificing the animal, thereby allowing the study of the transcriptome at various time points within a single individual. By comparing these venom-derived transcriptomes to the traditional whole-telson transcriptomes we show that the relative expression levels of the major toxin classes are similar. We further performed a multi-day extraction using our proposed method to show the possibility of doing a multiple time point transcriptome analysis. This allows for the study of patterns of toxin gene activation over time a single individual, and allows assessment of the effects of diet, season and other factors that are known or likely to influence intraindividual venom composition. We discuss the gland characteristics that may allow this method to be successful in scorpions and provide a review of other venomous taxa to which this method may potentially be successfully applied.

Structural and functional characterization of NDBP-4 family antimicrobial peptides from the scorpion Mesomexovis variegatus

Six peptides, belonging to the NDBP-4 family of scorpion antimicrobial peptides were structurally and functionally characterized. The sequence of the mature peptides VpCT1, VpCT2, VpCT3 and VpCT4 was inferred by transcriptomic analysis of the venom gland of the scorpion Mesomexovis variegatus. Analysis of their amino acid sequences revealed patterns that are also present in previously reported peptides that show differences in their hemolytic and antimicrobial activities in vitro. Two other variants, VpCT3W and VpCTConsensus were designed to evaluate the effect of sequence changes of interest on their structure and activity. The synthesized peptides were evaluated by circular dichroism to confirm their α-helical conformation in a folding promoting medium. The peptides were assayed on two Gram-positive and three Gram-negative bacterial strains, and on two yeast strains. They preferentially inhibited the growth of Staphylococcus aureus, were mostly ineffective on Pseudomonas aeruginosa, and moderately inhibited the growth of Candida yeasts. All six peptides exhibited hemolytic activity on human erythrocytes in the range of 4.8-83.7 μM. VpCT3W displayed increased hemolytic and anti-yeast activities, but showed no change in antibacterial activity, relative to its parental peptide, suggesting that Trp6 may potentiate the interaction of VpCT3 with eukaryotic cell membranes. VpCTConsensus showed broader and enhanced antimicrobial activity relative to several of the natural peptides. The results presented here contribute new information on the structure and function of NDBP-4 antimicrobial peptides and provides clues for the design of less hemolytic and more effective antimicrobial peptides.

Effects of climate variables on the incidence of scorpion stings in Iran for five years

Background:

Although scorpionism is recorded worldwide, some regions such as Iran present a higher incidence. Due to the great prevalence of scorpion stings in Khuzestan province, southwestern Iran, the present study examined the relationship between different climate parameters and the scorpion sting rate in this area from April 2010 to March 2015.

Methods:

In this cross-sectional descriptive-analytical study, we considered all scorpion sting cases recorded in the Department of Infectious Diseases, Ahvaz Jundishapur University of Medical Sciences. Data were analyzed using statistics, frequency distribution and Pearson’s correlation coefficient.

Results:

A total of 104,197 cases of scorpion stings was recorded from 2010 to 2015. The cumulative incidence of scorpion sting was 2.23%. The spatial distribution of scorpion stings showed that most cases occurred in the Dehdez district (4,504 scorpion stings/100,000 inhabitants) and the Masjed Soleyman county (4,069 scorpion stings/100,000 inhabitants). A significant association was found between climate factors (temperature, evaporation rate, sunshine duration, humidity, and precipitation) and the scorpion sting rate. An increase in rainfall and humidity coincided with a reduction in scorpion stings whereas an increase in temperature, evaporation, and sunshine duration was accompanied by a growth of scorpion stings. No significant correlation was found between wind velocity/direction and the incidence rate of stings. Moreover, the seasonal peak incidence of scorpion stings was recorded in summer (an average of 8,838 cases) and the lowest incidence was recorded during winter (an average of 1,286 cases). The annual trend of scorpion sting cases decreased during the period from 2010 to 2015.

Conclusion:

Climate variables can be a good index for predicting the incidence of scorpion stings in endemic regions. Since they occur mostly in the hot season, designing preventive measures in the counties and districts with a high incidence of scorpion stings such as Dehdez and Masjed Soleyman can minimize mortality and other burdens.

Mass spectrometry-based top-down and bottom-up approaches for proteomic analysis of the Moroccan Buthus occitanus scorpion venom

Buthus occitanus (B. occitanus) is one of the most dangerous scorpions in the world. Despite the involvement of B. occitanus scorpion in severe cases of envenomation in Morocco, no study has focused yet on the proteomic composition of the Moroccan B. occitanus scorpion venom. Mass spectrometry‐based proteomic techniques are commonly used in the study of scorpion venoms. The implementation of top‐down and bottom‐up approaches for proteomic analyses facilitates screening by allowing a global view of the structural aspects of such complex matrices. Here, we provide a partial overview of the venom of B. occitanus scorpion, in order to explore the diversity of its toxins and hereafter understand their effects. To this end, a combination of top‐down and bottom‐up approaches was applied using nano‐high liquid chromatography coupled to nano‐electrospray tandem mass spectrometry (nano‐LC‐ESI MS/MS). The LC‐MS results showed that B. occitanus venom contains around 200 molecular masses ranging from 1868 to 16 720 Da, the most representative of which are those between 5000 and 8000 Da. Interestingly, combined top‐down and bottom‐up LC‐MS/MS results allowed the identification of several toxins, which were mainly those acting on ion channels, including those targeting sodium (NaScTxs), potassium (KScTxs), chloride (ClScTxs), and calcium channels (CaScTx), as well as antimicrobial peptides (AMPs), amphipathic peptides, myotropic neuropeptides, and hypothetical secreted proteins. This study reveals the molecular diversity of B. occitanus scorpion venom and identifies components that may have useful pharmacological activities.

Trp: a conserved aromatic residue crucial to the interaction of a scorpion peptide with sodium channels

Anti-tumour-analgesic peptide (AGAP), one scorpion toxin purified from Buthus martensii Karsch, was known as its analgesic and anti-tumour activities. Trp38, a conserved aromatic residue of AGAP, might play important roles in its interaction with sodium channels. In this study, a mutant W38F was generated and effects of W38F were examined on hNav1.4, hNav1.5 and hNav1.7 by using whole-cell patch-clamp, which were closely associated to the biotoxicity of skeletal and cardiac muscles and pain signalling. The data showed that W38F decreased the inhibition effects of peak currents of hNav1.7, hNav1.4 and hNav1.5 compared with AGAP, notably, W38F reduced the analgesic activity compared with AGAP. The results suggested that Trp38 be a crucial amino acid involved in the interaction with these three sodium channels. The decreased analgesic activity of W38F might result from its much less inhibition of hNav1.7. These findings provided more information about the relationship between structure and function of AGAP and may facilitate the modification of other scorpion toxins with pharmacological effects.

Identification of an antiviral component from the venom of the scorpion Liocheles australasiae using transcriptomic and mass spectrometric analyses

Scorpion venom contains a variety of biologically active peptides. Among them, neurotoxins are major components in the venom, but it also contains peptides that show antimicrobial activity. Previously, we identified three insecticidal peptides from the venom of the Liocheles australasiae scorpion, but activities and structures of other venom components remained unknown. In this study, we performed a transcriptome analysis of the venom gland of the scorpion L. australasiae to gain a comprehensive understanding of its venom components. The result shows that potassium channel toxin-like peptides were the most diverse, whereas only a limited number of sodium channel toxin-like peptides were observed. In addition to these neurotoxin-like peptides, many non-disulfide-bridged peptides were identified, suggesting that these components have some critical roles in the L. australasiae venom. In this study, we also isolated a component with antiviral activity against hepatitis C virus using a bioassay-guided fractionation approach. By integrating mass spectrometric and transcriptomic data, we successfully identified LaPLA₂-1 as an anti-HCV component. LaPLA₂-1 is a phospholipase A₂ having a heterodimeric structure that is N-glycosylated at the N-terminal region. Since the antiviral activity of LaPLA₂-1 was inhibited by a PLA₂ inhibitor, the enzymatic activity of LaPLA₂-1 is likely to be involved in its antiviral activity.

Novel components of Tityus serrulatus venom: A transcriptomic approach

Several research groups have studied the components produced by the venom gland of the scorpion Tityus serrulatus, which has one of the most lethal venoms in the world. Various methodologies have been employed to clarify the complex mechanisms of action of these components, especially neurotoxins and enzymes. Transcriptomes and proteomes have provided important information for pharmacological, biochemical, and immunological research. Next-generation sequencing (NGS) has allowed the description of new transcripts and completion of partial sequence descriptions for peptides, especially those with low expression levels. In the present work, after NGS sequencing, we searched for new putative venom components. We present a total of nine new transcripts with neurotoxic potential (Ts33-41) and describe the sequences of one hyaluronidase (TsHyal_4); three enzymes involved in amidation (peptidyl-glycine alpha-amidating monooxygenase A, peptidyl-alpha-hydroxyglycine alpha-amidating lyase, and peptidylglycine alpha-hydroxylating monooxygenase), which increases the lethal potential of neurotoxins; and also the enzyme Ts_Chitinase1, which may be involved in the venom's digestive action. In addition, we determined the level of transcription of five groups: toxins, metalloproteases, hyaluronidases, chitinases and amidation enzymes, including new components found in this study. Toxins are the predominant group with an expression level of 91.945%, followed by metalloproteases with only 7.790% and other groups representing 0.265%.

Scorpion Venom: Detriments and Benefits

Scorpion venom may cause severe medical complications and untimely death if injected into the human body. Neurotoxins are the main components of scorpion venom that are known to be responsible for the pathological manifestations of envenoming. Besides neurotoxins, a wide range of other bioactive molecules can be found in scorpion venoms. Advances in separation, characterization, and biotechnological approaches have enabled not only the development of more effective treatments against scorpion envenomings, but have also led to the discovery of several scorpion venom peptides with interesting therapeutic properties. Thus, scorpion venom may not only be a medical threat to human health, but could prove to be a valuable source of bioactive molecules that may serve as leads for the development of new therapies against current and emerging diseases. This review presents both the detrimental and beneficial properties of scorpion venom toxins and discusses the newest advances within the development of novel therapies against scorpion envenoming and the therapeutic perspectives for scorpion toxins in drug discovery.

Scorpion stings in pregnancy: an analysis of outcomes in 66 envenomed pregnant patients in Iran

Background:

Scorpionism is one of the most important health problems in tropical regions, which unfortunately results in thousands of deaths annually. Pregnant women are potential victims in areas with high scorpion-sting prevalence. Limited medical data are available on the effects of scorpion envenomation in pregnant women. This study aimed to examine the effect of scorpion envenomation on pregnancy outcomes in 66 cases.

Methods:

The present descriptive/analytical cross-sectional study was performed on 66 scorpion-envenomed pregnant women referred to the clinical toxicology unit of Ahvaz Razi Hospital in Iran during 2015-2017. The variables assessed in all cases, via questionnaire and hospital medical records, were: age, patient residency, gestational week, status of the fetus, laboratory anomalies, clinical severity of envenomation, sting site and scorpion species. Pregnancy outcome (miscarriage, stillbirth, preterm birth, normal delivery) and status of the newborns were also evaluated. Data were analyzed using SPSS ^® software (version 24.0).

Results:

The following pregnancy outcomes were recorded from envenomed pregnant women: miscarriage = 1.5% (n = 1), stillbirth = 4.5% (n = 3), preterm birth = 10.6% (n = 7), normal birth = 83% (n = 55). Among participants whose pregnancy led to birth, 11(17.7%) cases had prenatal-neonatal complications. Neonatal complications, including Apgar score less than 8 points at 5 min, were found in 7 (11.3%) preterm birth cases and in 4 (6.4%) normal birth cases, along with birth weight below 2500 g in normal births. A significant relationship was found between adverse pregnancy outcomes and bite location, as well as scorpion species, but no relationship was found with other variables.

Conclusion:

Envenomation significantly contributes to preterm birth. Moreover, the location of bites and the type of scorpion species have a decisive role in the pregnancy outcome of scorpion-envenomed pregnant women.

Australian Scorpion Hormurus waigiensis Venom Fractions Show Broad Bioactivity Through Modulation of Bio-Impedance and Cytosolic Calcium

Scorpion venoms are a rich source of bioactive molecules, but characterisation of toxin peptides affecting cytosolic Ca2+, central to cell signalling and cell death, is limited. We undertook a functional screening of the venom of the Australian scorpion Hormurus waigiensis to determine the breadth of Ca2+ mobilisation. A human embryonic kidney (HEK293) cell line stably expressing the genetically encoded Ca2+ reporter GCaMP5G and the rabbit type 1 ryanodine receptor (RyR1) was developed as a biosensor. Size-exclusion Fast Protein Liquid Chromatography separated the venom into 53 fractions, constituting 12 chromatographic peaks. Liquid chromatography mass spectroscopy identified 182 distinct molecules with 3 to 63 components per peak. The molecular weights varied from 258 Da-13.6 kDa, with 53% under 1 kDa. The majority of the venom chromatographic peaks (tested as six venom pools) were found to reversibly modulate cell monolayer bioimpedance, detected using the xCELLigence platform (ACEA Biosciences). Confocal Ca2+ imaging showed 9/14 peak samples, with molecules spanning the molecular size range, increased cytosolic Ca2+ mobilization. H. waigiensis venom Ca2+ activity was correlated with changes in bio-impedance, reflecting multi-modal toxin actions on cell physiology across the venom proteome.

Transcriptomic and proteomic analyses of the venom and venom glands of Centruroides hirsutipalpus, a dangerous scorpion from Mexico

Centruroides hirsutipalpus (Scorpiones: Buthidae) is related to the "striped scorpion" group inhabiting the western Pacific region of Mexico. Human accidents caused by this species are medically important due to the great number of people stung and the severity of the resulting intoxication. This communication reports an extensive venom characterization using high-throughput proteomic and Illumina transcriptomic sequencing performed with RNA purified from its venom glands. 2,553,529 reads were assembled into 44,579 transcripts. From these transcripts, 23,880 were successfully annoted using Trinotate. Using specialized databases and by performing bioinformatic searches, it was possible to identify 147 putative venom protein transcripts. These include α- and β-type sodium channel toxins (NaScTx), potassium channel toxins (KScTx) (α-, β-, δ-, γ- and λ-types), enzymes (metalloproteases, hyaluronidases, phospholipases, serine proteases, and monooxygenases), protease inhibitors, host defense peptides (HDPs) such as defensins, non-disulfide bridge peptides (NDBPs), anionic peptides, superfamily CAP proteins, insulin growth factor-binding proteins (IGFBPs), orphan peptides, and other venom components (La1 peptides). De novo tandem mass spectrometric sequencing of digested venom identificatied 50 peptides. The venom of C. hirsutipalpus contains the highest reported number (77) of transcripts encoding NaScTxs, which are the components responsible for human fatalities.

Transcriptome annotation and characterization of novel toxins in six scorpion species

Background

Venom has evolved in parallel in multiple animals for the purpose of self-defense, prey capture or both. These venoms typically consist of highly complex mixtures of toxins: diverse bioactive peptides and/or proteins each with a specific pharmacological activity. Because of their specificity, they can be used as experimental tools to study cell mechanisms and develop novel medicines and drugs. It is therefore potentially valuable to explore the venoms of various animals to characterize their toxins and identify novel toxin-families. This study focuses on the annotation and exploration of the transcriptomes of six scorpion species from three different families. The transcriptomes were annotated with a custom-built automated pipeline, primarily consisting of Basic Local Alignment Search Tool searches against UniProt databases and filter steps based on transcript coverage.

Results

We annotated the transcriptomes of four scorpions from the family Buthidae, one from Iuridae and one from Diplocentridae using our annotation pipeline. We found that the four buthid scorpions primarily produce disulfide-bridged ion-channel targeting toxins, while the non-buthid scorpions have a higher abundance of non-disulfide-bridged toxins. Furthermore, analysis of the “unidentified” transcripts resulted in the discovery of six novel putative toxin families containing a total of 37 novel putative toxins. Additionally, 33 novel toxins in existing toxin-families were found. Lastly, 19 novel putative secreted proteins without toxin-like disulfide bonds were found.

Conclusions

We were able to assign most transcripts to a toxin family and classify the venom composition for all six scorpions. In addition to advancing our fundamental knowledge of scorpion venomics, this study may serve as a starting point for future research by facilitating the identification of the venom composition of scorpions and identifying novel putative toxin families.

Electronic supplementary material

The online version of this article (10.1186/s12864-019-6013-6) contains supplementary material, which is available to authorized users.

Transcriptomic and Proteomic Analysis of the Tentacles and Mucus of Anthopleura dowii Verrill, 1869

Sea anemone venom contains a complex and diverse arsenal of peptides and proteins of pharmacological and biotechnological interest, however, only venom from a few species has been explored from a global perspective to date. In the present study, we identified the polypeptides present in the venom of the sea anemone Anthopleura dowii Verrill, 1869 through a transcriptomic and proteomic analysis of the tentacles and the proteomic profile of the secreted mucus. In our transcriptomic results, we identified 261 polypeptides related to or predicted to be secreted in the venom, including proteases, neurotoxins that could act as either potassium (K⁺) or sodium (Na⁺) channels inhibitors, protease inhibitors, phospholipases A2, and other polypeptides. Our proteomic data allowed the identification of 156 polypeptides—48 exclusively identified in the mucus, 20 in the tentacles, and 88 in both protein samples. Only 23 polypeptides identified by tandem mass spectrometry (MS/MS) were related to the venom and 21 exclusively identified in the mucus, most corresponding to neurotoxins and hydrolases. Our data contribute to the knowledge of evolutionary and venomic analyses of cnidarians, particularly of sea anemones.

Smp76, a Scorpine-Like Peptide Isolated from the Venom of the Scorpion Scorpio maurus palmatus, with a Potent Antiviral Activity Against Hepatitis C Virus and Dengue Virus

Growing global viral infections have been a serious public health problem in recent years. This current situation emphasizes the importance of developing more therapeutic antiviral compounds. Hepatitis C virus (HCV) and dengue virus (DENV) belong to the Flaviviridae family and are an increasing global health threat. Our previous study reported that the crude venom of Scorpio maurus palmatus possessed anti-HCV and anti-DENV activities in vitro. We report here the characterization of a natural antiviral peptide (scorpion-like peptide Smp76) that prevents HCV and DENV infection. Smp76 was purified from S. m. palmatus venom and contains 76 amino acids with six residues of cysteine. Smp76 antiviral activity was evaluated using a cell culture technique utilizing Huh7it-1, Vero/SLAM, HCV (JFH1, genotype 2a) and DENV (Trinidad 1751, type 2). A potential antiviral activity of Smp76 was detected in culture cells with an approximate IC₅₀ of 0.01 μg/ml. Moreover, Smp76 prevents HCV infection and suppresses secondary infection, by inactivating extra-cellular infectious particles without affecting viral replication. Interestingly, Smp76 is neither toxic nor hemolytic in vitro at a concentration 1000-fold higher than that required for antiviral activity. Conclusively, this report highlights novel anti-HCV and anti-DENV activities of Smp76, which may lay the foundation for developing a new therapeutic intervention against these flaviviruses.

Dissecting Toxicity: The Venom Gland Transcriptome and the Venom Proteome of the Highly Venomous Scorpion Centruroides limpidus (Karsch, 1879)

Venom glands and soluble venom from the Mexican scorpion Centruroides limpidus (Karsch, 1879) were used for transcriptomic and proteomic analyses, respectively. An RNA-seq was performed by high-throughput sequencing with the Illumina platform. Approximately 80 million reads were obtained and assembled into 198,662 putative transcripts, of which 11,058 were annotated by similarity to sequences from available databases. A total of 192 venom-related sequences were identified, including Na⁺ and K⁺ channel-acting toxins, enzymes, host defense peptides, and other venom components. The most diverse transcripts were those potentially coding for ion channel-acting toxins, mainly those active on Na⁺ channels (NaScTx). Sequences corresponding to β- scorpion toxins active of K⁺ channels (KScTx) and λ-KScTx are here reported for the first time for a scorpion of the genus Centruroides. Mass fingerprint corroborated that NaScTx are the most abundant components in this venom. Liquid chromatography coupled to mass spectometry (LC-MS/MS) allowed the identification of 46 peptides matching sequences encoded in the transcriptome, confirming their expression in the venom. This study corroborates that, in the venom of toxic buthid scorpions, the more abundant and diverse components are ion channel-acting toxins, mainly NaScTx, while they lack the HDP diversity previously demonstrated for the non-buthid scorpions. The highly abundant and diverse antareases explain the pancreatitis observed after envenomation by this species.

Biochemical characterization of the venom of Central American scorpion Didymocentrus krausi Francke, 1978 (Diplocentridae) and its toxic effects in vivo and in vitro

Venoms of medically important scorpions from Buthidae family have been intensively studied, in contrast to non-buthid venoms, for which knowledge is scarce. In this work, we characterized the venom of a Diplocentridae species, Didymocentrus krausi, a small fossorial scorpion that inhabits the Tropical Dry Forest of Central America. D. krausi venom soluble fraction contains proteases with enzymatic activity on gelatin and casein. Mass spectrometry and venomic analysis confirmed the presence of elastase-like, cathepsin-O-like proteases and a neprilysin-like metalloproteinase. We did not detect phospholipase A₂, C or D, nor hyaluronidase activity in the venom. By homology-based venom gland transcriptomic analysis, NDBPs, a β-KTx-like peptide, and other putative toxin transcripts were found, which, together with a p-benzoquinone compound present in the venom, could potentially explain its direct hemolytic and cytotoxic effects in several mammalian cell lines. Cytotoxicity of D. krausi venom was higher than the effect of venoms from two buthid scorpion species distributed in Costa Rica, Centruroides edwardsii and Tityus pachyurus. Even though D. krausi venom was not lethal to mice or crickets, when injected in mouse gastrocnemius muscle at high doses it induced pathological effects at 24 h, which include myonecrosis, weak hemorrhage, and inflammatory infiltration. We observed an apparent thrombotic effect in the skin blood vessels, but no in vitro fibrinogenolytic activity was detected. In crickets, D. krausi venom induced toxicity and paralysis in short periods of time.

Transcriptomic and Proteomic Analyses Reveal the Diversity of Venom Components from the Vaejovid Scorpion Serradigitus gertschi

To understand the diversity of scorpion venom, RNA from venomous glands from a sawfinger scorpion, Serradigitus gertschi, of the family Vaejovidae, was extracted and used for transcriptomic analysis. A total of 84,835 transcripts were assembled after Illumina sequencing. From those, 119 transcripts were annotated and found to putatively code for peptides or proteins that share sequence similarities with the previously reported venom components of other species. In accordance with sequence similarity, the transcripts were classified as potentially coding for 37 ion channel toxins; 17 host defense peptides; 28 enzymes, including phospholipases, hyaluronidases, metalloproteases, and serine proteases; nine protease inhibitor-like peptides; 10 peptides of the cysteine-rich secretory proteins, antigen 5, and pathogenesis-related 1 protein superfamily; seven La1-like peptides; and 11 sequences classified as "other venom components". A mass fingerprint performed by mass spectrometry identified 204 components with molecular masses varying from 444.26 Da to 12,432.80 Da, plus several higher molecular weight proteins whose precise masses were not determined. The LC-MS/MS analysis of a tryptic digestion of the soluble venom resulted in the de novo determination of 16,840 peptide sequences, 24 of which matched sequences predicted from the translated transcriptome. The database presented here increases our general knowledge of the biodiversity of venom components from neglected non-buthid scorpions.

A paratransgenic strategy to block transmission of Xylella fastidiosa from the glassy-winged sharpshooter Homalodisca vitripennis

Background

Arthropod-borne diseases remain a leading cause of human morbidity and mortality and exact an enormous toll on global agriculture. The practice of insecticide-based control is fraught with issues of excessive cost, human and environmental toxicity, unwanted impact on beneficial insects and selection of resistant insects. Efforts to modulate insects to eliminate pathogen transmission have gained some traction and remain future options for disease control.

Results

Here, we report a paratransgenic strategy that targets transmission of Xylella fastidiosa, a leading bacterial pathogen of agriculture, by the Glassy-Winged Sharpshooter (GWSS), Homalodisca vitripennis. Earlier, we identified Pantoea agglomerans, a bacterial symbiont of the GWSS as the paratransgenic control agent. We genetically engineered P. agglomerans to express two antimicrobial peptides (AMP)-melittin and scorpine-like molecule (SLM). Melittin and SLM were chosen as the effector molecules based on in vitro studies, which showed that both molecules have anti-Xylella activity at concentrations that did not kill P. agglomerans. Using these AMP-expressing strains of P. agglomerans, we demonstrated disruption of pathogen transmission from insects to grape plants below detectable levels.

Conclusion

This is the first report of halting pathogen transmission from paratransgenically modified insects. It is also the first demonstration of paratransgenic control in an agriculturally important insect vector.

Electronic supplementary material

The online version of this article (10.1186/s12896-018-0460-z) contains supplementary material, which is available to authorized users.

Spermaurin, an La1-like peptide from the venom of the scorpion Scorpio maurus palmatus, improves sperm motility and fertilization in different mammalian species

STUDY QUESTION

Is it possible to identify original compounds that are able to enhance sperm motility from the venom of the scorpion Scorpio maurus palmatus?

SUMMARY ANSWER

We identified a potent disulfide-rich peptide (DRP) of 73 amino acids that significantly improved the motility of fresh and frozen-thawed sperm in different mammalian species, including human, and improved fertilization outcome in mouse IVF experiments.

WHAT IS KNOWN ALREADY

Any disturbance of sperm motility has a strong impact on fertilization and can lead to subfertility or infertility. Significant efforts have, therefore,  been made to identify pharmacological drugs that might improve sperm motility. Such compounds are particularly useful in azoospermia to improve testicular sperm extraction and in the domain of cryopreservation because the motility of frozen-thawed sperm is reduced.

STUDY DESIGN, SIZE, DURATION

This was a basic science/medical research study aimed at identifying original compounds from a library of venoms able to enhance mammalian sperm motility, including human. We first identified in the venom of a scorpion S. m. palmatus a fraction able to potently activate sperm motility. We next purified and characterized the compound by liquid chromatography, mass spectrometry and peptide synthesis. Finally, the potency and toxicity of both purified and synthetic versions of the identified compound on sperm motility were assessed using different in vitro tests in different mammalian species.

PARTICIPANTS/MATERIALS, SETTING, METHODS

For human sperm, biological samples were collected from normozoospermic donors and subfertile patients attending a reproduction department for diagnostic semen analysis. Testicular sperm was collected from cynomolgus monkeys (Macaca fascicularis) euthanized for the needs of specific authorized research projects. The peptide was also tested on bovine and mouse epidydimal sperm. We measured different sperm motility parameters with a computer-assisted sperm analysis system in the presence or absence of the peptide.

MAIN RESULTS AND THE ROLE OF CHANCE

Size exclusion chromatography enabled us to isolate a fraction of the venom of S. m. palmatus able to increase sperm motility. By liquid chromatography and mass spectrometry, a peptide comprising 73 amino acids with 4 disulfide bridges was identified as responsible for the biological activity and called 'spermaurin'. The identity of spermaurin was confirmed by chemical synthesis. We showed that the peptide increased the motility of fresh and frozen-thawed human sperm. We observed that the potency of the peptide was higher on fresh ejaculated spermatozoa with a low motility, achieving a 100% increase of curvilinear velocity in poorly performing sperm. We also demonstrated that peptide is effective on bovine and mouse fresh epididymal, bovine frozen-thawed ejaculated and fresh non-human primate testicular sperm. Finally, in mouse IVF, the production of 2-cell embryos was increased by 24% when sperm were treated with the peptide.

LIMITATIONS, REASONS FOR CAUTION

This work is an in vitro evaluation of the ability of spermaurin to improve sperm motility parameters. Another limitation of this study is the small number of human sperm samples tested with the natural (n = 36) and synthetic (n = 12) peptides. Moreover, the effect of the peptide on IVF outcome was only tested in mouse and further tests with human and bovine gametes are required to confirm and extend this result in other mammalian species.

WIDER IMPLICATIONS OF THE FINDINGS

This work confirms our initial study showing that venoms represent an interesting source of molecules that are able to modify sperm physiology. Moreover, this work presents the first demonstrated biological action of a venom peptide from the scorpion S. m. palmatus with sequence similarities to La1 peptide from Liocheles australasiae (Wood scorpion), a widespread family of DRPs.

LARGE SCALE DATA

Not applicable.

STUDY FUNDING/COMPETING INTEREST(S)

This work is part of the project 'LAB COM-14 LAB7 0004 01-LIPAV', funded by the program LabCom 2014 from the French Research Agency (ANR). Dr Arnoult reports grants from IMV Technologies during the conduct of the study. In addition, Drs Arnoult, Martinez, Ray and Schmitt have a patent EP16305642.7 pending containing some of the information presented in this manuscript.

First Transcriptome Analysis of Iranian Scorpion, Mesobuthus Eupeus Venom Gland

Scorpions are generally an important source of bioactive components, including toxins and other small peptides as attractive molecules for new drug development. Mesobuthus eupeus, from medically important and widely distributed Buthidae family, is the most abundant species in Iran. Researchers are interesting on the gland of this scorpion due to the complexity of its venom. Here, we have analyzed the transcriptome based on expressed sequence tag (EST) database from the venom tissue of Iranian M. eupeus by constructing a cDNA library and subsequent Sanger sequencing of obtained inserts. Sixty-three unique transcripts were identified, which were grouped in different categories, including Toxins (44 transcripts), Cell Proteins (9 transcripts), Antimicrobial Peptides (4 transcripts) and Unknown Peptides (3 transcripts). The analysis of the ESTs revealed several new components categorized among various toxin families with effect on ion channels. Sequence analysis of a new precursor provides evidence to validate the first CaTxs from M. eupeus. The results are exploration of the diversity of precursors expressed of Iranian M. eupeus venom gland. We further described comparative analysis of venom components of Iranian M. eupeus with other sibling species.

A Deeper Examination of Thorellius atrox Scorpion Venom Components with Omic Techonologies

This communication reports a further examination of venom gland transcripts and venom composition of the Mexican scorpion Thorellius atrox using RNA-seq and tandem mass spectrometry. The RNA-seq, which was performed with the Illumina protocol, yielded more than 20,000 assembled transcripts. Following a database search and annotation strategy, 160 transcripts were identified, potentially coding for venom components. A novel sequence was identified that potentially codes for a peptide with similarity to spider ω-agatoxins, which act on voltage-gated calcium channels, not known before to exist in scorpion venoms. Analogous transcripts were found in other scorpion species. They could represent members of a new scorpion toxin family, here named omegascorpins. The mass fingerprint by LC-MS identified 135 individual venom components, five of which matched with the theoretical masses of putative peptides translated from the transcriptome. The LC-MS/MS de novo sequencing allowed to reconstruct and identify 42 proteins encoded by assembled transcripts, thus validating the transcriptome analysis. Earlier studies conducted with this scorpion venom permitted the identification of only twenty putative venom components. The present work performed with more powerful and modern omic technologies demonstrates the capacity of accomplishing a deeper characterization of scorpion venom components and the identification of novel molecules with potential applications in biomedicine and the study of ion channel physiology.

Differential toxicity and venom gland gene expression in Centruroides vittatus

Variation in venom toxicity and composition exists in many species. In this study, venom potency and venom gland gene expression was evaluated in Centruroides vittatus, size class I-II (immature) and size class IV (adults/penultimate instars) size classes. Venom toxicity was evaluated by probit analysis and returned ED₅₀ values of 50.1 μg/g for class IV compared to 134.2 μg/g for class I-II 24 hours post injection, suggesting size class IV was 2.7 fold more potent. Next generation sequencing (NGS and qPCR were used to characterize venom gland gene expression. NGS data was assembled into 36,795 contigs, and annotated using BLASTx with UNIPROT. EdgeR analysis of the sequences showed statistically significant differential expression in transcripts associated with sodium and potassium channel modulation. Sodium channel modulator expression generally favored size class IV; in contrast, potassium channel modulators were favored in size class I-II expression. Real-time quantitative PCR of 14 venom toxin transcripts detected relative expression ratios that paralleled NGS data and identified potential family members or splice variants for several sodium channel modulators. Our data suggests ontogenetic differences in venom potency and venom related genes expression exist between size classes I-II and IV.

A mutant of the Buthus martensii Karsch antitumor-analgesic peptide exhibits reduced inhibition to hNav1.4 and hNav1.5 channels while retaining analgesic activity

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 hNa_v1.4 and hNa_v1.5, 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 hNa_v1.4 and hNa_v1.5; 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 Na_v1.7 and Na_v1.8 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.

Discovery of three toxin peptides with Kv1.3 channel and IL-2 cytokine-inhibiting activities from Non-Buthidae scorpions, Chaerilus tricostatus and Chaerilus tryznai

Non-Buthidae venomous scorpions are huge natural sources of toxin peptides; however, only a few studies have been done to understand their toxin peptides. Herein, we describe three new potential immunomodulating toxin peptides, Ctri18, Ctry68 and Ctry2908, from two non-Buthidae scorpions, Chaerilus tricostatus and Chaerilus tryznai. Sequence alignment analyses showed that Ctri18, Ctry68 and Ctry2908 are three new members of the scorpion toxin α-KTx15 subfamily. Electrophysiological experiments showed that Ctri18, Ctry68 and Ctry2908 blocked the Kv1.3 channel at micromole to nanomole levels, but had weak effects on potassium channel KCNQ1 and sodium channel Nav1.4, which indicated that Ctri18, Ctry68 and Ctry2908 might have specific inhibiting effects on the Kv1.3 channel. ELISA experiments showed that Ctri18, Ctry68 and Ctry2908 inhibited IL-2 cytokine secretions of activated T lymphocyte in human PBMCs. Excitingly, consistent with the good Kv1.3 channel inhibitory activity, Ctry2908 inhibited cytokine IL-2 secretion in nanomole level, which indicated that Ctry2908 might be a new lead drug template toward Kv1.3 channels. Together, these studies discovered three new toxin peptides, Ctri18, Ctry68 and Ctry2908, with Kv1.3 channel and IL-2 cytokine-inhibiting activities from two scorpions, C. tricostatus and C. tryznai, and highlighted that non-Buthidae venomous scorpions are new natural toxin peptide sources.

Recombinant expression of Intrepicalcin from the scorpion Vaejovis intrepidus and its effect on skeletal ryanodine receptors

BACKGROUND

Scorpion venoms contain toxins that modulate ionic channels, among which are the calcins, a small group of short, basic peptides with an Inhibitor Cystine Knot (ICK) motif that target calcium release channels/ryanodine receptors (RyRs) with high affinity and selectivity. Here we describe the heterologous expression of Intrepicalcin, identified by transcriptomic analysis of venomous glands from Vaejovis intrepidus.

METHODS

Recombinant Intrepicalcin was obtained in Escherichia coli BL21-DE3 (periplasm) by fusing the Intrepicalcin gene to sequences coding for signal-peptide, thioredoxin, His-tag and enterokinase cleavage site.

RESULTS

[³H]Ryanodine binding, used as a functional index of RyR activity, revealed that recombinant Intrepicalcin activates skeletal RyR (RyR1) dose-dependently with K_d=17.4±4.0nM. Intrepicalcin significantly augments the bell-shaped [Ca²⁺]-[³H]ryanodine binding curve at all [Ca²⁺] ranges, as is characteristic of the calcins. In single channel recordings, Intrepicalcin induces the appearance of a subconductance state in RyR1 with a fractional value ∼55% of the full conductance state, very close to that of Vejocalcin. Furthermore, Intrepicalcin stimulates Ca²⁺ release at an initial dose=45.3±2.5nM, and depletes ~50% of Ca²⁺ load from skeletal sarcoplasmic reticulum vesicles.

CONCLUSIONS

We conclude that active recombinant Intrepicalcin was successfully obtained without the need of manual oxidation, enabling it to target RyR1s with high affinity.

GENERAL SIGNIFICANCE

This is the first calcin heterologously expressed in the periplasma of Escherichia coli BL21-DE3, shown to be pharmacologically effective, thus paving the way for the generation of Intrepicalcin variants that are required for structure-function relationship studies of calcins and RyRs.

Bioactivity of Natural and Engineered Antimicrobial Peptides from Venom of the Scorpions Urodacus yaschenkoi and U. manicatus

The spread of multidrug-resistant human pathogens has drawn attention towards antimicrobial peptides (AMPs), which are major players in the innate immune systems of many organisms, including vertebrates, invertebrates, plants and microbes. Scorpion venom is an abundant source of novel and potent AMPs. Here, we investigated natural and engineered AMPs from the scorpions Urodacus yaschenkoi and U. manicatus to determine their antimicrobial spectra as well as their hemolytic/cytotoxic activity. None of the AMPs were active against fungi, but many of them were active at low concentrations (0.25–30 µM) against seven different bacteria. Hemolytic and cytotoxic activities were determined using pig erythrocytes and baby hamster kidney cells, respectively. The amino acid substitutions in the engineered AMPs did not inhibit cytotoxicity, but reduced hemolysis and therefore increased the therapeutic indices. The phylogenetic analysis of scorpion AMPs revealed they are closely related and the GXK motif is highly conserved. The engineered scorpion AMPs offer a promising alternative for the treatment of multidrug-resistant bacterial infections and could be modified further to reduce their hemolytic/cytotoxic activity.

Venom Gland Transcriptomic and Proteomic Analyses of the Enigmatic Scorpion Superstitionia donensis (Scorpiones: Superstitioniidae), with Insights on the Evolution of Its Venom Components

Venom gland transcriptomic and proteomic analyses have improved our knowledge on the diversity of the heterogeneous components present in scorpion venoms. However, most of these studies have focused on species from the family Buthidae. To gain insights into the molecular diversity of the venom components of scorpions belonging to the family Superstitioniidae, one of the neglected scorpion families, we performed a transcriptomic and proteomic analyses for the species Superstitionia donensis. The total mRNA extracted from the venom glands of two specimens was subjected to massive sequencing by the Illumina protocol, and a total of 219,073 transcripts were generated. We annotated 135 transcripts putatively coding for peptides with identity to known venom components available from different protein databases. Fresh venom collected by electrostimulation was analyzed by LC-MS/MS allowing the identification of 26 distinct components with sequences matching counterparts from the transcriptomic analysis. In addition, the phylogenetic affinities of the found putative calcins, scorpines, La1-like peptides and potassium channel κ toxins were analyzed. The first three components are often reported as ubiquitous in the venom of different families of scorpions. Our results suggest that, at least calcins and scorpines, could be used as molecular markers in phylogenetic studies of scorpion venoms.

Scorpion toxin peptide action at the ion channel subunit level

This review categorizes functionally validated actions of defined scorpion toxin (SCTX) neuropeptides across ion channel subclasses, highlighting key trends in this rapidly evolving field. Scorpion envenomation is a common event in many tropical and subtropical countries, with neuropharmacological actions, particularly autonomic nervous system modulation, causing significant mortality. The primary active agents within scorpion venoms are a diverse group of small neuropeptides that elicit specific potent actions across a wide range of ion channel classes. The identification and functional characterisation of these SCTX peptides has tremendous potential for development of novel pharmaceuticals that advance knowledge of ion channels and establish lead compounds for treatment of excitable tissue disorders. This review delineates the unique specificities of 320 individual SCTX peptides that collectively act on 41 ion channel subclasses. Thus the SCTX research field has significant translational implications for pathophysiology spanning neurotransmission, neurohumoral signalling, sensori-motor systems and excitation-contraction coupling. This article is part of the Special Issue entitled 'Venom-derived Peptides as Pharmacological Tools.'

Transcriptomic analysis of the venom glands from the scorpion Hadogenes troglodytes revealed unique and extremely high diversity of the venom peptides

Hadogenes is a genus of large African scorpions with 18 described species. However, little is known about the venom peptide composition of any species from Hadogenes so far. Here, we fully explored the composition of venom gland peptides from Hadogenes troglodytes using transcriptomic approach. We discovered 121 novel peptides from the scorpion, including 20 new-type peptides cross-linked with one, two, three, four or seven disulfide bridges, respectively, 11 novel K⁺-channel toxin-like peptides, 2 novel ryanodine receptors-specific toxin-like peptides, a unique peptide containing the cysteine knots of spider toxins, 15 novel La1-like toxins, 3 novel TIL domain-containing peptides, 5 novel peptides with atypical cysteine patterns, 19 novel antimicrobial peptides, 6 novel cysteine-free peptides and 39 new-type cysteine-free peptides. Among them, the new-type peptides are largely dominant; this highlights the unique diversity of the venom gland peptides from H. troglodytes. Some of the new peptides would serve as new molecular probes for the investigations of cellular ion channels and other receptors, or offer new templates for the development of therapeutic drugs for the treatment of ion channel-associated diseases, and infections caused by antibiotics-resistant pathogens.

BIOLOGICAL SIGNIFICANCE

In this study, we fully explored the composition of venom gland peptides from the scorpion Hadogenes troglodytes using transcriptomic approach. We discovered a total of 121 novel peptides from the venom glands of the scorpion, of which new-type peptides are largely dominant. These data highlight the unique diversity of the venom gland peptides from the scorpion H. troglodytes, gain insights into new mechanisms for the scorpion to subdue its prey and predators, and enlarge the protein database of scorpion venom glands. The discovery of a lot of novel peptides provides new templates for the development of therapeutic drugs, and offers new molecular materials for the basic researches of various cellular receptors, and for the evolutionary investigations of scorpion toxins.

Cardiorespiratory alterations in rodents experimentally envenomed with Hadruroides lunatus scorpion venom

Background

Hadruroides lunatus is the most abundant scorpion species in the Peruvian central coast, where most of the accidents involving humans are registered. In spite of its prevalence, there are only very few studies on H. lunatus envenomation. The aim of the present study was to analyze the cardiorespiratory alterations caused by H. lunatus envenomation in rodents.

Methods

Wistar rats injected with H. lunatus scorpion venom were submitted to electrocardiography. After euthanasia, rat lungs were collected and histopathologically analyzed. Mouse cardiomyocytes were used to perform immunofluorescence and calcium transient assays. Data were analyzed by ANOVA or Student’s t-test. The significance level was set at p < 0.05.

Results

It was observed that H. lunatus venom increased heart rate and caused arrhythmia, thereby impairing the heart functioning. Lungs of envenomed animals showed significant alterations, such as diffuse hemorrhage. In addition, immunofluorescence showed that H. lunatus venom was capable of binding to cardiomyocytes. Furthermore, mouse ventricular cardiomyocytes incubated with H. lunatus venom showed a significant decrease in calcium transient, confirming that H. lunatus venom exerts a toxic effect on heart.

Conclusion

Our results showed that H. lunatus venom is capable of inducing cardiorespiratory alterations, a typical systemic effect of scorpionism, stressing the importance of medical monitoring in envenomation cases.