Characterization of venom components from the scorpion Androctonus crassicauda of Turkey: Peptides and genes

Proteomic analysis and lethality of the venom of Aegaeobuthus nigrocinctus, a scorpion of medical significance in the Middle East

The scorpion Aegaeobuthus nigrocinctus inhabits areas in Turkey and the Levant region of the Middle East where severe/lethal envenomings have been reported. Previous research indicated its extreme venom lethality to vertebrates and distinct envenomation syndrome. We report on the composition of A. nigrocinctus venom from Lebanese specimens using nESI-MS/MS, MALDI-TOF MS, SDS-PAGE and RP-HPLC. Venom lethality in mice was also assessed (LD50 = 1.05 (0.19-1.91) mg/kg, i.p), confirming A. nigrocinctus venom toxicity from Levantine populations. Forty-seven peaks were resolved using RP-HPLC, 25 of which eluted between 20 and 40 % acetonitrile. In reducing SDS-PAGE, most predominant components were <10 kDa, with minor components at higher molecular masses of 19.6, 26.1, 46.3 and 57.7 kDa. MALDI-TOF venom fingerprinting detected 20 components within the 1,000-12,000 m/z range. Whole venom 'shotgun' bottom-up nLC-MS/MS approach, combined with in-gel tryptic digestion of SDS-PAGE bands, identified at least 67 different components belonging to 15 venom families, with ion channel-active components (K+ toxins (23); Na+ toxins (20); Cl- toxins (2)) being predominant. The sequence of a peptide (named α-KTx9.13) ortholog to Leiurus hebraeus putative α-KTx9.3 toxin was fully determined, which exhibited 81-96 % identity to other members of the α-KTx9 subfamily targeting Kv1.x and Ca2+-activated K+ channels. Chlorotoxin-like peptides were also identified. Our study underscores the medical significance of A. nigrocinctus in the region and reveals the potential value of its venom components as lead templates for biomedical applications. Future work should address whether available antivenoms in the Middle East are effective against A. nigrocinctus envenoming in the Levant area.

Antihelimentic effect of Androctonus crassicauda scorpion venom against Trichuris arvicolae isolated from Psammomys obesus in Egypt

Trichuridae family has a genetic and morphological variability between species affecting rodents, but it is considerably hard to morphologically diagnose species within the genus of Trichuris and the individuals of these species are identified according to their host, as it is known that Trichuris spp. is strictly host-specific. However, some species lack host specificity. So, it is necessary to use molecular data in order to well identify the Trichuris spp. in Egyptian rodents. The host examined in the current research is Psammomys obesus and the molecularly identified species from its cecum is Trichuris arvicolae. In addition, Trichuris arvicolae was subjected to in vitro treatment with Androctonus crassicauda Crude Venom as a model of natural alternative treatment for gastrointestinal nematodes that increasingly develop anthelmintic drug resistance. The changes in Trichuris arvicolae were monitored using scanning electron microscopy, Androctonus crassicauda Crude Venom made a significant ultrastructural surface changes in Trichuris arvicolae, including marked cuticular sloughing, disintegrated bacillary glands, bursting of vulva and edema of anal region. This study was done for closer identification of Trichuris spp. infecting rodents in Egypt and evaluating the efficacy of Androctonus crassicauda Crude Venom in vitro.

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.

Recombinant expression and antigenicity of two peptide families of neurotoxins from Androctonus sp

Background

Scorpion neurotoxins such as those that modify the mammalian voltage-gated sodium ion channels (Nav) are the main responsible for scorpion envenomation. Their neutralization is crucial in the production of antivenoms against scorpion stings.

Methods

In the present study, two in silico designed genes - one that codes for a native neurotoxin from the venom of the Anatolian scorpion Androctonus crassicauda, named Acra 4 - and another non-native toxin - named consensus scorpion toxin (SccTx) obtained from the alignment of the primary structures of the most toxic neurotoxins from the Middle Eastern and North African scorpions - were recombinantly expressed in E. coli Origami.

Results

Following bacterial expression, the two expressed neurotoxins, hereafter named HisrAcra4 and HisrSccTx, were obtained from inclusion bodies. Both recombinant neurotoxins were obtained in multiple Cys-Cys isoforms. After refolding, the active protein fractions were identified with molecular masses of 8,947.6 and 9,989.1 Da for HisrAcra4 and HisrSccTx, respectively, which agreed with their expected theoretical masses. HisrAcra4 and HisrSccTx were used as antigens to immunize two groups of rabbits, to produce either anti-HisrAcra4 or anti-HisrSccTx serum antibodies, which in turn could recognize and neutralize neurotoxins from venoms of scorpion species from the Middle East and North Africa. The antibodies obtained from rabbits neutralized the 3LD₅₀ of Androctonus australis, Leiurus quinquestriatus hebraeus and Buthus occitanus venoms, but they did not neutralize A. crassicauda and A. mauritanicus venoms. In addition, the anti-HisrAcra4 antibodies did not neutralize any of the five scorpion venoms tested. However, an antibody blend of anti-HisrAcra4 and anti-HisrSccTx was able to neutralize A. crassicauda and A. mauritanicus venoms.

Conclusions

Two recombinant Nav neurotoxins, from different peptide families, were used as antigens to generate IgGs for neutralizing scorpion venoms of species from the Middle East and North Africa.

Characterization of the first two toxins isolated from the venom of the ancient scorpion Tityus (Archaeotityus) mattogrossensis (Borelli, 1901)

Background:

Almost all Tityus characterized toxins are from subgenera Atreus and Tityus, there are only a few data about toxins produced by Archaeotityus, an ancient group in Tityus genus.

Methods:

Tityus (Archaeotityus) mattogrossensis crude venom was fractionated by high performance liquid chromatography, the major fractions were tested in a frog sciatic nerve single sucrose-gap technique. Two fractions (Tm1 and Tm2) were isolated, partially sequenced by MALDI-TOF/MS and electrophysiological assayed on HEK293 Nav 1.3, HEK293 Nav 1.6, DUM and DRG cells.

Results:

The sucrose-gap technique showed neurotoxicity in four fractions. One fraction caused a delay of action potential repolarization and other three caused a reduction in amplitude. An electrophysiological assay showed that Tm1 is active on HEK293 Nav 1.3, HEK293 Nav 1.6, DUM and DRG cells, and Tm2 on HEK293 Nav 1.3 and DRG cells, but not in HEK293 Nav 1.6. In addition, Tm1 and Tm2 did promote a shift to more negative potentials strongly suggesting that both are α-NaScTx.

Conclusion:

Although Tityus (Archaeotityus) mattogrossensis is considered an ancient group in Tityus genus, the primary structure of Tm1 and Tm2 is more related to Tityus subgenus. The patch clamp electrophysiological tests suggest that Tm1 and Tm2 are NaScTx, and also promoted no shift to more negative potentials, strongly suggesting that both are α-NaScTx. This paper aimed to explore and characterize for the first time toxins from the ancient scorpion Tityus (Archaeotityus) mattogrossensis.

Toxicity and protein composition of venoms of Hottentotta saulcyi, Hottentotta schach and Androctonus crassicauda, three scorpion species collected in Iran

BACKGROUND

Scorpion stings comprise a serious problem throughout the globe, especially in regions where they are more frequent. Despite a recent upsurge of interest in scorpion venoms by various research groups, there remain many challenges.

OBJECTIVE

Therefore, in this study, we aimed to study the toxicity and protein composition of venoms of Hottentotta saulcyi, Hottentotta schach and Androctonus crassicauda, three scorpion species collected in Iran.

MATERIALS AND METHODS

Scorpion species were collected from Esfahan farm scorpion company and maintained in the laboratory in containers that mimic their natural habitat. Venom was extracted from A. crassicauda, H. schach and H. saulcyi by electrical stimulation of 8 and 10 V. The toxicity of each venom was established by using four groups of male Swiss albino mice aged 2 months (weighting 18-20 g) for testing each dose of venom. One group was used as a control. Venom was injected into mice by subcutaneous route. Then, animals were monitored for 24 h and LD₅₀ was estimated by the graphic method of Miller and Tainter. Thus, high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was used to determine amino acids in the venom, and protein concentrations were determined by the Biuret method.

RESULTS

LD₅₀ of scorpion venoms by subcutaneous route was found to be 1.70 mg/kg b.w (A. crassicauda), 1.47 mg/kg b.w (H. saulcyi) and 0.85 mg/kg b.w (H. schach). A. crassicauda, H. saulcyi and H. schach contain 26, 30, and 31 amino acids, respectively. A. crassicauda contains low concentrations of alpha-aminoadipic acid, beta-aminoisobutyric acid, beta-alanine and citrulline. H. saulcyi contains a concentration of hydroxylysine, whereas H. schach has no such concentration. A. crassicauda also had the highest levels of tyrosine and threonine. Only A. crassicauda venom contains a low proportion of proteins (14.80%) compared with those of H. schach (16.26%) and H. saulcyi (16.20%). Albumin content in the venoms was 11.7% (H. saulcyi), 5.4% (H. schach) and 4.4% (A. crassicauda).

CONCLUSION

Scorpions venoms have a variable toxicity and an interesting composition in amino acids and proteins. Work on the development of anti-venom is fundamental.

Peptidomic characterization and bioactivity of Protoiurus kraepelini (Scorpiones: Iuridae) venom

Protoiurus kraepelini is a scorpion species found in parts of Turkey and Greece. In this study, the peptide profile of its venom was determined for the first time. The electrophoretic profile of the crude venom showed a protein distribution from 2 to 130 kDa. MALDI-TOF MS analysis of the venom peptide fraction yielded 27 peptides between 1059 and 4623 Da in mass. Several ion channelblocking and antimicrobial peptides were identified by peptide mass fingerprinting analysis. Cytotoxic and antimicrobial effects of the venom were also demonstrated on Jurkat cells and Escherichia coli, respectively. As the first peptidomic characterization study on P. kraepelini venom, this report lays the foundation for detailed future studies that may lead to the discovery of novel bioactive peptides.

Determination of median effective dose (ED50) of scorpion antivenom against scorpion envenomation using a newly developed formula

BACKGROUND

About 50 species of scorpions cause fatal scorpionism worldwide. Most of these are members of the Buthidae family, and include, among others, Mesobuthus eupeus, Androctonus crassicauda, Leiurus abdullahbayrami, Leiurus quinquestriatus, Tityus pachyurus and Androctonus australis. Because high doses of scorpion venom and antivenom can cause death and hypersensitive reactions, there is a need to develop a formula that can be used to calculate both lethal and effective doses for scorpion venom and antivenom, respectively, thereby obviating the need for laboratory experiments.

METHODS

In view of this, a literature search was carried out with the aim of modifying the formula (LD 50 = ED 50 3 × W a × 10 - 4 ) for calculation of the median lethal dose (LD50) of scorpion venom and the ED50 of antivenom. The human equivalent dose (HED) formula was assessed for extrapolation of LD50 and ED50 from animals to human for comparison and relevance with the new formula.

RESULTS

The findings showed that the newly developed formula (LD50 = ED50 1/3 × W a  × 10-4) yielded results that are very close to the reported values. Therefore, the newly developed and HED formulas can be used for calculation of LD50 and ED50 values for scorpion venom and antivenom, respectively.

CONCLUSION

The new formula yielded better results than the HED formula, confirming its predictive validity, precision, and reliability, thereby obviating the need for rigorous experiments and justifying the principles of reduction, refinement, and replacement (3Rs).

Comparative analyses and implications for antivenom serotherapy of four Moroccan scorpion Buthus occitanus venoms: Subspecies tunetanus, paris, malhommei, and mardochei

Temporary passive immunity such as serotherapy against venoms requires the full knowledge of all venom's components. Here, four venoms from Moroccan common yellow scorpions belonging to Buthus occitanus, subspecies tunetanus, paris, malhommei, and mardochei, all collected in four different restricted areas, were analysed in deep. They were fractionated by reversed-phase high-performance liquid chromatography (RP-HPLC) and their molecular masse profile determined by off-line MALDI-TOF mass spectrometry. Characterisation of their main components was achieved by enzyme-linked immunosorbent assay (ELISA) using specific antisera against the major lethal scorpion toxins identified so far, i.e. voltage-gated sodium channels (Na_v) modulators α- and β-toxins, as well as diverse potassium channel pore blocker toxins. For fractions with identical RP-HPLC retention times, we observe that their relative quantities show large differences. Moreover, identical masses present simultaneously in the four venoms are infrequent. ELISAs show that the majority of the RP-HPLC compounds cross-react with the antiserum against the "α-like" toxin Bot I, which has been previously identified in the Algerian Buthus occitanus tunetanus venom. Moreover, minor fractions were recognised by the antiserum against the highly lethal "classical" α-toxin of reference AaH II from the Androctonus australis venom. As such, our results bring new sights for further improving scorpion venom serotherapy in Morocco.

Medical application of scorpion venom to breast cancer: A mini-review

Breast cancer is the leading cause of mortality in women worldwide. Today, 1 in 8 women born in the United States will have an invasive cancer in their lifetime. Despite significant attempts, the prognosis of metastatic breast cancer still remains poor. This has compelled scientists to look elsewhere for better therapeutic outcomes. Recent advances in venomic studies have demonstrated some promise in cancer-related ailments. Scorpion venom, a complex cocktail of biogenic amines, proteins, peptides, mucoproteins, organic salts and neurotoxins has shown a potential therapeutic application due to its cytotoxic, apoptogenic, immunosuppressive and antiproliferative properties. This communication reviews the effects of scorpion venom components on breast cancer and their mechanisms.

Induction of IL-12 from human monocytes after stimulation with Androctonus crassicauda scorpion venom

The objective of this study was to evaluate the capacity of venom from Androctonus crassicauda to induce expression/production of interleukin (IL)-12 by isolated human monocytes. For this purpose, isolated human monocytes were exposed to different concentrations of the venom (0.16-20 μg/ml) for varying periods (6, 12, and 24 h). Apart from measures of venom cytotoxicity (i.e., lactase dehydrogenase activity [LDH] release), measures of IL-12 p40 mRNA (by Real-time PCR) of IL-12 release (by ELISA) were performed. The results showed that the venom produced significant concentration- and duration of incubation-dependent cytotoxicity. Expression of IL-12 p40 mRNA was significantly increased at all exposure timepoints relative to that in unexposed cells, but was maximal after 6 h of exposure. At that timepoint, the effect from a dose of 2.5 μg venom/ml provided the maximal increase among all doses tested. At the level of the protein itself, IL-12 production remained almost consistently elevated (vs. unexposed control values) across all exposure timepoints, with the greatest formation again occurring after 6 h of incubation at a dose of 2.5 μg venom/ml. The findings from this study demonstrated that venom from the A. crassicauda scorpion contained active constituents that could induce a sustained activation of human monocytes that was manifested, in part, as promotion of the expression/production of IL-12.

Whole Transcriptome of the Venom Gland from Urodacus yaschenkoi Scorpion

Australian scorpion venoms have been poorly studied, probably because they do not pose an evident threat to humans. In addition, the continent has other medically important venomous animals capable of causing serious health problems. Urodacus yaschenkoi belongs to the most widely distributed family of Australian scorpions (Urodacidae) and it is found all over the continent, making it a useful model system for studying venom composition and evolution. This communication reports the whole set of mRNA transcripts produced by the venom gland. U. yaschenkoi venom is as complex as its overseas counterparts. These transcripts certainly code for several components similar to known scorpion venom components, such as: alpha-KTxs, beta-KTxs, calcins, protease inhibitors, antimicrobial peptides, sodium-channel toxins, toxin-like peptides, allergens, La1-like, hyaluronidases, ribosomal proteins, proteasome components and proteins related to cellular processes. A comparison with the venom gland transcriptome of Centruroides noxius (Buthidae) showed that these two scorpions have similar components related to biological processes, although important differences occur among the venom toxins. In contrast, a comparison with sequences reported for Urodacus manicatus revealed that these two Urodacidae species possess the same subfamily of scorpion toxins. A comparison with sequences of an U. yaschenkoi cDNA library previously reported by our group showed that both techniques are reliable for the description of the venom components, but the whole transcriptome generated with Next Generation Sequencing platform provides sequences of all transcripts expressed. Several of which were identified in the proteome, but many more transcripts were identified including uncommon transcripts. The information reported here constitutes a reference for non-Buthidae scorpion venoms, providing a comprehensive view of genes that are involved in venom production. Further, this work identifies new putative bioactive compounds that could be used to seed research into new pharmacological compounds and increase our understanding of the function of different ion channels.

Characterization of Leiurus abdullahbayrami (Scorpiones: Buthidae) venom: peptide profile, cytotoxicity and antimicrobial activity

BACKGROUND

Scorpion venoms are rich bioactive peptide libraries that offer promising molecules that may lead to the discovery and development of new drugs. Leiurus abdullahbayrami produces one of the most potent venoms among Turkish scorpions that provokes severe symptoms in envenomated victims.

METHODS

In the present study, the peptide profile of the venom was investigated by electrophoretic methods, size-exclusion and reversed-phase chromatography and mass spectroscopy. Cytotoxic and antimicrobial effects were evaluated on a breast cancer cell line (MCF-7) and various bacterial and fungal species.

RESULTS

Proteins make up approximately half of the dry weight of L. abdullahbayrami crude venom. Microfluidic capillary electrophoresis indicated the presence of 6 to 7 kDa peptides and proved to be a highly practical peptidomics tool with better resolution when compared to conventional polyacrylamide gel electrophoresis. Mass spectroscopy analysis helped us to identify 45 unique peptide masses between 1 to 7 kDa with a bimodal mass distribution peaking between molecular weights of 1 to 2 kDa (29%) and 3 to 4 kDa (31%). L. abdullahbayrami crude venom had a proliferative effect on MCF-7 cells, which may be explained by the high concentration of polyamines as well as potassium and calcium ions in the arachnid venoms. Antimicrobial effect was stronger on gram-negative bacteria.

CONCLUSIONS

This work represents the first peptidomic characterization of L. abdullahbayrami venom. Considering the molecular weight-function relationship of previously identified venom peptides, future bioactivity studies may lead to the discovery of novel potassium and chloride ion channel inhibitors as well as new antimicrobial peptides from L. abdullahbayrami venom.

The anti-proliferative effects and mechanisms of low molecular weight scorpion BmK venom peptides on human hepatoma and cervical carcinoma cells in vitro

Peptides from scorpion venom have been previously studied for use in the prevention and treatment of various types of cancer in folk medicine. The present study investigated the anti-proliferative effects and mechanisms of the low molecular weight (~3 kDa) BmK scorpion venom peptides (LMWSVP) on human hepatoma (SMMC 7721) and cervical carcinoma (HeLa) cells. The data indicated that LMWSVP inhibited the growth of SMMC 7721 cells, but had no effect on the growth of HeLa cells. SMMC 7721 cells were more sensitive, with a higher affinity, to LMWSVP as compared with HeLa cells. In addition, LMWSVP induced apoptosis of SMMC 7721 cells by upregulating the expression of caspase-3 and downregulating the expression of Bcl-2. These data provide an experimental basis for further purification and application of LMWSVP for use as an anti-tumor drug in clinical trials.

The Mediterranean scorpion Mesobuthus gibbosus (Scorpiones, Buthidae): transcriptome analysis and organization of the genome encoding chlorotoxin-like peptides

Background

Transcrof toxin genes of scorpion species have been published. Up to this moment, no information on the gene characterization of M. gibbosus is available.

Results

This study provides the first insight into gene expression in venom glands from M. gibbosus scorpion. A cDNA library was generated from the venom glands and subsequently analyzed (301 clones). Sequences from 177 high-quality ESTs were grouped as 48 Mgib sequences, of those 48 sequences, 40 (29 “singletons” and 11 “contigs”) correspond with one or more ESTs. We identified putative precursor sequences and were grouped them in different categories (39 unique transcripts, one with alternative reading frames), resulting in the identification of 12 new toxin-like and 5 antimicrobial precursors (transcripts). The analysis of the gene families revealed several new components categorized among various toxin families with effect on ion channels. Sequence analysis of a new KTx precursor provides evidence to validate a new KTx subfamily (α-KTx 27.x). A second part of this work involves the genomic organization of three Meg-chlorotoxin-like genes (ClTxs). Genomic DNA sequence reveals close similarities (presence of one same-phase intron) with the sole genomic organization of chlorotoxins ever reported (from M. martensii).

Conclusions

Transcriptome analysis is a powerful strategy that provides complete information of the gene expression and molecular diversity of the venom glands (telson). In this work, we generated the first catalogue of the gene expression and genomic organization of toxins from M. gibbosus. Our result represents a relevant contribution to the knowledge of toxin transcripts and complementary information related with other cell function proteins and venom peptide transcripts. The genomic organization of the chlorotoxin genes may help to understand the diversity of this gene family.

Overview of scorpion species from China and their toxins

Scorpions are one of the most ancient groups of terrestrial animals. They have maintained a steady morphology over more than 400 million years of evolution. Their venom arsenals for capturing prey and defending against predators may play a critical role in their ancient and conservative appearance. In the current review, we present the scorpion fauna of China: 53 species covering five families and 12 genera. We also systematically list toxins or genes from Chinese scorpion species, involving eight species covering four families. Furthermore, we review the diverse functions of typical toxins from Chinese scorpion species, involving Na⁺ channel modulators, K⁺ channel blockers, antimicrobial peptides and protease inhibitors. Using scorpion species and their toxins from China as an example, we build the bridge between scorpion species and their toxins, which helps us to understand the molecular and functional diversity of scorpion venom arsenal, the dynamic and functional evolution of scorpion toxins, and the potential relationships of scorpion species and their toxins.

A first exploration of the venom of the Buthus occitanus scorpion found in southern France

Even though Buthus occitanus scorpions are found throughout the Mediterranean region, a lack of distinctive characteristics has hampered their classification into different subspecies. Yet, stings from this particular scorpion family are reported each year to result in pain followed by various toxic symptoms. In order to determine the toxicity origin of the rare French B. occitanus Amoreux scorpion, we collected several specimens and studied their venom composition using a nano ultra high performance liquid chromatography and matrix assisted laser desorption/ionisation time-of-flight mass spectrometry (nano UHPLC/MALDI-TOF-MS) automated workflow combined with an enzyme-linked immunosorbent assay (ELISA) approach. Moreover, we compared this dataset to that obtained from highly lethal Androctonus australis and Androctonus mauretanicus scorpions collected in North Africa. As a result, we found that the B. occitanus Amoreux venom is toxic to mice, an observation that is most likely caused by venom components that inhibit voltage-gated sodium channel inactivation. Moreover, we identified similarities in venom composition between B. occitanus scorpions living in the South of France and other Buthidae collected in Morocco and Algeria. As such, the results of this study should be taken into consideration when treating stings from the B. occitanus species living in the South of France.

Biological assays on the effects of Acra3 peptide from Turkish scorpion Androctonus crassicauda venom on a mouse brain tumor cell line (BC3H1) and production of specific monoclonal antibodies

Constitutes of the venom scorpion are a rich source of low molecular mass peptides which are toxic to various organisms, including man. Androctonus crassicauda is one of the scorpions from the Southeastern Anatolia of Turkey with public health importance. This work is focused on the investigation of biological effects of Acra3 peptide from Androctonus crassicauda. For this purpose, Acra3 isolated from crude venoms was tested for its cytotoxicity on BC3H1 mouse brain tumor cells using tetrazolium salt cleavage and lactate dehydrogenase activity assays. To determine whether the cytotoxic effects of Acra3 was related to the induction of apoptosis, the morphology of the cells and the nuclear fragmentation was examined by using Acridin Orange staining and DNA fragmentation assay, respectively. Caspase 3 and caspase 9 activities were measured spectrophotometrically and flow cytometric assay was performed using Annexin-V FITC and Propidium Iodide staining. Furthermore toxic peptide Acra3 was used as an antigen for immunological studies. Results showed that Acra3 exerted very strong cytotoxic effect on BC3H1 cells with an IC50 value of 5 μg/ml. Exposure of the cells to 0.1 and 0.5 μg/ml was resulted in very strong appearance of the apoptotic morphology in a dose dependent manner. On the other side, not any DNA fragmentation was observed after treatment of the cells. Caspase 3 and 9 activities were slightly decreased with Acra3. Results from flow cytometry and lactate dehydrogenase activity assays indicate that Acra3 exerts its effects by inducing a stronger necrosis than apoptosis in BC3H1 cells. To evaluate its immunogenicity, monoclonal antibody (MAb) specific for Acra3 antigen (5B9) was developed by hybridoma technology using spleen and lymph nodes of mice and immunoglobulin type of antibody was found to be IgM. We suggest that Acra3 may exert its effects by inducing both necrotic and apoptotic pathway in some way on mouse brain tumor cells. These findings will be useful for understanding the mechanism of cell death caused by venom in vitro. Anti-Acra3 monoclonal antibody can be further used as a bioactive tools for exploring the structure/function relationship and the pharmacological mechanism of scorpion peptide neurotoxins.

Molecular cloning and biochemical characterization of the first Na(+)-channel α-type toxin peptide (Acra4) from Androctonus crassicauda scorpion venom

Due to the medical importance played in Turkey by stings of the scorpion Androctonus crassicauda, its venom has been studied with more attention. In this communication we report a new toxic peptide, named Acra4, because it is the fourth peptide completely characterized from venom of this scorpion. The peptide contains 64 amino acid residues stabilized by four disulfide bridges, with a molecular weight of 6937 Da. Purification of the lethal peptide was performed by three steps of high performance liquid chromatography (HPLC) separations, and the molecular weight was determined by mass spectrometry analysis and the full amino acid sequence was obtained by direct Edman degradation in conjunction with gene cloning. The LD50 of Acra4 was 50.5 ng/20 g mouse body weight (95% confidence intervals from 48.8 to 52.2 ng/20 g mouse body weight). Additionally, from a sample of cDNA of A. crassicauda four genes were cloned displaying sequence similarities to known scorpion toxins, and are reported here as potentially toxic peptides, named Acra5 to Acra8. Electrophysiological studies of Acra4 were performed using Na(+)-channels expressed in F11 cell culture, by patch-clamp recordings. This is the first time that such peptide from A. crassicauda having a specific Na(+)-channel α-type effect is reported. Its affinity toward Na(+)-channels in F11 cell line is in the order of 1 μM concentration.

Novel potassium channel blocker venom peptides from Mesobuthus gibbosus (Scorpiones: Buthidae)

In the present study, we report for the first time, the molecular, biochemical and electrophysiological characterization of the components present in the soluble venom from Mesobuthus gibbosus (Brullé, 1832). According to the epidemiological and clinical situation of scorpion envenomation cases M. gibbosus scorpion is one of the most important health-threatening species of Turkey. Despite the medical importance reported for M. gibbosus, there is no additional information on toxin peptides and venom components to clarify the toxic effect of the M. gibbosus sting. Biochemical characterization of the venom was performed using different protocols and techniques following a bioassay-guided strategy (HPLC, mass spectrometry and Edman degradation sequencing). Venom fractions were tested in electrophysiological assays on a panel of six K(+) channels (K(v)1.1-1.6) by using the two-electrode voltage clamp technique. Three new α-KTx peptides were found and called MegKTx1, MegKTx2 and MegKTx3 (M. gibbosus, K(+) channel toxin number 1-3). A cDNA library from the telson was constructed and specific screening of transcripts was performed. Biochemical and molecular characterization of MegKTx peptides and transcripts shows a relation with toxins of three different α-KTx subfamilies (α-KTx3.x, α-KTx9.x and α-KTx16.x).

Purification and cDNA cloning of a novel neurotoxic peptide (Acra3) from the scorpion Androctonus crassicauda

Androctonus crassicauda is one of the Southeastern Anatolian scorpions of Turkey with ethno-medical and toxicological importance. Two toxic peptides (Acra1 and Acra2) were isolated and characterized from the venom of this scorpion. In this communication, the isolation of an additional toxin (Acra3) by chromatographic separations (HPLC and TSK-gel sulfopropyl) and its chemical and functional characterization is reported. Acra3 is a 7620Da molecular weight peptide, with 66 amino acid residues crosslinked by four disulfide bridges. The gene coding for this peptide was cloned and sequenced. Acra3 is anticipated to undergo post-translational modifications at the C-terminal region, having an amidated serine as last residue. Injection of Acra3 induces severe neurotoxic events in mice, such as: excitability and convulsions, leading to the death of the animals within a few minutes after injection. Electrophysiological assays conducted with pure Acra3, using cells that specifically expressed sodium channels (Nav1.1-Nav1.6) showed no clear effect. The exact molecular target of Acra3 remained undiscovered, similar to three other scorpion peptides that clustered very closely in the phylogenetic tree included here. The exact target of these four peptides is not very clear.

Identification and phylogenetic analysis of Tityus pachyurus and Tityus obscurus novel putative Na+-channel scorpion toxins

Background

Colombia and Brazil are affected by severe cases of scorpionism. In Colombia the most dangerous accidents are caused by Tityus pachyurus that is widely distributed around this country. In the Brazilian Amazonian region scorpion stings are a common event caused by Tityus obscurus. The main objective of this work was to perform the molecular cloning of the putative Na⁺-channel scorpion toxins (NaScTxs) from T. pachyurus and T. obscurus venom glands and to analyze their phylogenetic relationship with other known NaScTxs from Tityus species.

Methodology/Principal Findings

cDNA libraries from venom glands of these two species were constructed and five nucleotide sequences from T. pachyurus were identified as putative modulators of Na⁺-channels, and were named Tpa4, Tpa5, Tpa6, Tpa7 and Tpa8; the latter being the first anti-insect excitatory β-class NaScTx in Tityus scorpion venom to be described. Fifteen sequences from T. obscurus were identified as putative NaScTxs, among which three had been previously described, and the others were named To4 to To15. The peptides Tpa4, Tpa5, Tpa6, To6, To7, To9, To10 and To14 are closely related to the α-class NaScTxs, whereas Tpa7, Tpa8, To4, To8, To12 and To15 sequences are more related to the β-class NaScTxs. To5 is possibly an arthropod specific toxin. To11 and To13 share sequence similarities with both α and β NaScTxs. By means of phylogenetic analysis using the Maximum Parsimony method and the known NaScTxs from Tityus species, these toxins were clustered into 14 distinct groups.

Conclusions/Significance

This communication describes new putative NaScTxs from T. pachyurus and T. obscurus and their phylogenetic analysis. The results indicate clear geographic separation between scorpions of Tityus genus inhabiting the Amazonian and Mountain Andes regions and those distributed over the Southern of the Amazonian rainforest. Based on the consensus sequences for the different clusters, a new nomenclature for the NaScTxs is proposed.

Turkish scorpion Buthacus macrocentrus: general characterization of the venom and description of Bu1, a potent mammalian Na⁺-channel α-toxin

The venom of the scorpion Buthacus macrocentrus of Turkey was fractionated by high performance liquid chromatography (HPLC) and its mass finger print analysis was obtained by spectrometry. More than 70 different fractions were obtained, allowing the determination of the molecular masses of at least 60 peptides ranging between 648 and 44,336 Da. The venom is enriched with peptides containing molecular masses between 3200-4500 Da, and 6000-7500 Da. They very likely correspond to K⁺-channel and Na⁺-channel specific peptides, respectively, as expected from venoms of scorpions of the family Buthidae, already determined for other species. The major component obtained from HPLC was shown to be lethal to mice and was further purified and characterized. It contains 65 amino acid residues maintained closely packed by 4 disulfide bridges, and shows a molecular weight of 7263 Da. Additionally, a cDNA from the venomous glands of this scorpion was used in conjunction with sequence data from Edman degradation and mass spectrometry for cloning the gene that codes for Bu1 as we named this toxin. This gene codes for a 67 amino acid residues peptide, where the two last are eliminated post-translationally for production of an amidated C-terminal arginine. Its sequence is closely related to toxins from the species Leiurus quinquestriatus, as revealed by a phylogenetic tree analysis. Electrophysiological results conducted with Bu1 using patch-clamp techniques indicate that it modifies the Na⁺ currents, in a similar way as other well known α-scorpion toxins. These results support the conclusion that this species of scorpions is dangerous to humans, having an epidemiological interest for the country.

Scorpion and spider venom peptides: gene cloning and peptide expression

This communication reviews most of the important findings related to venom components isolated from scorpions and spiders, mainly by means of gene cloning and expression. Rather than revising results obtained by classical biochemical studies that report structure and function of venom components, here the emphasis is placed on cloning and identification of genes present in the venomous glands of these arachnids. Aspects related to cDNA library construction, specific or random ESTs cloning, transcriptome analysis, high-throughput screening, heterologous expression and folding are briefly discussed, showing some numbers of species and components already identified, but also shortly mentioning limitations and perspectives of research for the future in this field.

Characterization of three "Birtoxin-like" toxins from the Androctonus amoreuxi scorpion venom

The venom of the North African scorpion Androctonus amoreuxi (Aam) was analyzed using a combination of gel filtration, C18 reverse phase HPLC together with mass spectrometry analysis and bioassays. Three novel Birtoxin-like (BTX-L) peptides of 58 amino acid residues comprising three disulfide bridges were isolated and chemically characterized. One peptide, AamBTX-L3, induced serious toxic symptoms in mice and was lethal at nanogram quantities using intracerebroventricular injection. The three BTX-L peptides were tested in competition experiments on rat brain synaptosomes against the (125)I-labeled "classical" α- and β-toxins of reference, as well as with the (125)I-KTX, a voltage-gated potassium channel blocker. Only AamBTX-L3 was able to prevent the equilibrium binding of the β-toxin (125)I-Css IV to its receptor site 4 with a IC(50) value of 189 nM. Even if previous electrophysiological data allowed the classification of other BTX-L peptides among the β-type toxins, this report clearly shows that AamBTX-L3 is pharmacologically a β-toxin, which recognizes the voltage-gated Na(+) (Na(v)) channels from central mammalian neurons. In order to uncover the residues functionally essential for interaction between the AamBTX-L3 with the putative receptor site of (125)I-Css IV on Na(v)1.2, molecular models of the three novel Aam BTX-L molecules were made and their surfaces were compared to the already described Css IV biologically interactive surfaces. A hypothesis is given that in BTX-L3, three residues found in the α-helix play a key role during target binding.

Bioinformatic characterizations and prediction of K+ and Na+ ion channels effector toxins

BACKGROUND

K+ and Na+ channel toxins constitute a large set of polypeptides, which interact with their ion channel targets. These polypeptides are classified in two different structural groups. Recently a new structural group called birtoxin-like appeared to contain both types of toxins has been described. We hypothesized that peptides of this group may contain two conserved structural motifs in K+ and/or Na+ channels scorpion toxins, allowing these birtoxin-like peptides to be active on K+ and/or Na+ channels.

RESULTS

Four multilevel motifs, overrepresented and specific to each group of K+ and/or Na+ ion channel toxins have been identified, using GIBBS and MEME and based on a training dataset of 79 sequences judged as representative of K+ and Na+ toxins.Unexpectedly birtoxin-like peptides appeared to present a new structural motif distinct from those present in K+ and Na+ channels Toxins. This result, supported by previous experimental data, suggests that birtoxin-like peptides may exert their activity on different sites than those targeted by classic K+ or Na+ toxins.Searching, the nr database with these newly identified motifs using MAST, retrieved several sequences (116 with e-value < 1) from various scorpion species (test dataset). The filtering process left 30 new and highly likely ion channel effectors.Phylogenetic analysis was used to classify the newly found sequences. Alternatively, classification tree analysis, using CART algorithm adjusted with the training dataset, using the motifs and their 2D structure as explanatory variables, provided a model for prediction of the activity of the new sequences.

CONCLUSION

The phylogenetic results were in perfect agreement with those obtained by the CART algorithm.Our results may be used as criteria for a new classification of scorpion toxins based on functional motifs.

Proteins, lethality and in vivo effects of Iurus dufoureius asiaticus scorpion venom

Iurus dufoureius asiaticus, Birula, 1903 scorpions were collected in Mugla province located in the Aegean region, Turkey. There are few number of publications about I.d. asiaticus, and there are no data regarding minimal lethal dose and effects of the scorpion venom till now. This is the first study about toxicity and effects of I.d. asiaticus scorpion venom in mice. Previously, most of the proteins in venom of I.d. asiaticus from Aydin region in Turkey were reported to be between 14 and 205 kDa in size. In this study, we determined the electrophoretic protein pattern of the venom taken from Mugla province to be between 29 and 116 kDa by SDS-PAGE. Intracerebroventricular (i.c.v.) was determined instead of s.c. injection since there were no deaths in any s.c. test groups. The LD(50) of I.d. asiaticus scorpion venom was found to be 47.7 microg/20 g mouse by i.c.v. injection route. After s.c. injection venom, mice were shown any intoxication symptoms. On the other hand, after i.c.v. administration of venom, mice showed symptoms such as excitability, hyper salivation, weakness, paralysis, coma and resulting in death. The possible cause of death could be due to multi-system organ failure depending on the toxic effect of the venom. These both results showed that the venom was not lethal on s.c. injection, but it was lethal on i.c.v. injection. This may imply that the scorpion is of little danger to humans.

Identification of insect-selective and mammal-selective toxins from Parabuthus leiosoma venom

Venoms were collected from two scorpion species: Parabuthus leiosoma and Parabuthus pallidus from Kenya. Subcutaneous injection and oral toxicity tests of crude and pure fractions of scorpion venoms were done in Mus musculus (mice), Chilo partellus and Busseola fusca. The highest activity against C. partellus was found in P. leiosoma venom (LC(50) 0.689 mg/50mg body weight). Bioassay-guided purification by a combination of cation-exchange (CE) and reverse-phase high-performance liquid chromatography (RP-HPLC) led to the isolation of three toxic peptides. A lepidopteran-selective toxin (P. leiosoma insect toxin, Plit) was isolated, and the partial N-terminal amino acid sequence (-KDGYPVDNANCKYE-) plus the molecular weight (6688.5 Da) determined. A peptide with significant insect toxicity coupled with mild effects on mice (P. leiosoma toxin, Plt) was isolated, and the partial N-terminal amino acid sequence (-LCEKFKVQRLVELNCVD-) plus the molecular weight (6742.5 Da) was determined. Another toxin with anti-mammalian activity (P. leisoma mammal-selective toxin, Plmt), and N-terminal partial amino acid sequence of ADVPGNYPLDKNGNRYY- plus a molecular weight of 7145.5 Da was also isolated. Comparison of the partial N-terminal amino acid sequences with other toxins revealed that Plit shows high homology to other known insect toxins. Similarly, Plmt shows high homology with several birtoxin-like anti-mammalian toxins. Plt does not exhibit homology with any known scorpion toxin with combined anti-insect and anti-mammalian activity.

Transcriptome analysis of the venom gland of the Mexican scorpion Hadrurus gertschi (Arachnida: Scorpiones)

Background

Scorpions like other venomous animals posses a highly specialized organ that produces, secretes and disposes the venom components. In these animals, the last postabdominal segment, named telson, contains a pair of venomous glands connected to the stinger. The isolation of numerous scorpion toxins, along with cDNA-based gene cloning and, more recently, proteomic analyses have provided us with a large collection of venom components sequences. However, all of them are secreted, or at least are predicted to be secretable gene products. Therefore very little is known about the cellular processes that normally take place inside the glands for production of the venom mixture. To gain insights into the scorpion venom gland biology, we have decided to perform a transcriptomic analysis by constructing a cDNA library and conducting a random sequencing screening of the transcripts.

Results

From the cDNA library prepared from a single venom gland of the scorpion Hadrurus gertschi, 160 expressed sequence tags (ESTs) were analyzed. These transcripts were further clustered into 68 unique sequences (20 contigs and 48 singlets), with an average length of 919 bp. Half of the ESTs can be confidentially assigned as homologues of annotated gene products. Annotation of these ESTs, with the aid of Gene Ontology terms and homology to eukaryotic orthologous groups, reveals some cellular processes important for venom gland function; including high protein synthesis, tuned posttranslational processing and trafficking. Nonetheless, the main group of the identified gene products includes ESTs similar to known scorpion toxins or other previously characterized scorpion venom components, which account for nearly 60% of the identified proteins.

Conclusion

To the best of our knowledge this report contains the first transcriptome analysis of genes transcribed by the venomous gland of a scorpion. The data were obtained for the species Hadrurus gertschi, belonging to the family Caraboctonidae. One hundred and sixty ESTs were analyzed, showing enrichment in genes that encode for products similar to known venom components, but also provides the first sketch of cellular components, molecular functions, biological processes and some unique sequences of the scorpion venom gland.

Characterization of peptide components in the venom of the scorpion Liocheles australasiae (Hemiscorpiidae)

Scorpion venoms are composed of a number of neurotoxic peptides. A variety of toxins have been isolated from the venoms of scorpions of the family Buthidae, however, little interest has been paid to non-Buthidae scorpions. In this study, we examined the toxicity of the venom of Liocheles australasiae (Hemiscorpiidae) to mice and crickets, and characterized the peptide components by HPLC and mass spectrometry. Over 200 components were detected in the L. australasiae venom by LC/MS analysis, with components of molecular masses ranging from 500 to 5000 Da being particularly abundant. A number of peptides contained two to four disulfide bridges, which was estimated based on the mass difference after derivatization of Cys residues. A peptide having a monoisotopic molecular mass of 7781.6 Da and four disulfide bridges was isolated from the venom. The peptide has a primary structure similar in terms of the position of eight Cys residues to those observed in several peptides found from scorpions, ticks and insects, although biological roles of these peptides are unknown.

Mass fingerprinting of toxic fractions from the venom of the Indian red scorpion, Mesobuthus tamulus: biotope-specific variation in the expression of venom peptides

The red scorpion, Mesobuthus tamulus, is found in two distinct biotopes within the Indian state of Maharastra-a tropical, sea-level biotope and a semi-arid biotope, up to 600 m. Scorpions from these two geographical areas show marked differences in toxicity. Using mass spectrometry, we have shown biotope-specific variation in the expression of peptides from scorpions collected from these two distinct areas. Matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOFMS) and reversed-phase liquid chromatography/electrospray ionisation mass spectrometry (LC/ESI-MS) were assessed as techniques for obtaining mass fingerprint data. On line LC/ESI-MS was judged to be the method of choice and unique biotope-specific mass fingerprints, with key diagnostic markers, were obtained.