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PubMed2005

Divergent non-LTR retrotransposon lineages from the genomes of scorpions (Arachnida: Scorpiones).

We screened across the taxonomic diversity of order Scorpiones (22 species belonging to 21 genera and 10 families) for the presence of seven different clades of non-LTR retrotransposons in their genomes using PCR with newly designed clade-specific consensus-degenerate hybrid oligonucleotide primers. Scorpion genomes were found to contain four known non-LTR retrotransposon clades: R1, I, Jockey, and CR1. In total, 35 fragments of reverse transcriptase genes of new elements from 22 scorpion species were obtained and analyzed for three clades, Jockey, I, and CR1. Phylogenies of different clades of elements were built using amino acid sequences inferred from 33 non-LTR retrotransposon clones. Distinct evolutionary lineages, with several major groups of the non-LTR retroelements were identified, showing significant variation. Four lineages were revealed in Jockey clade. The phylogeny of I clade showed strong support for the monophyletic origin of such group of elements in scorpions. Three separate lineages can be distinguished in the phylogenetic tree of CR1 clade. The large fraction of the isolated elements appeared to be defective.

Animals↗
PubMed1989

Lack of effect of a neurotoxin from the scorpion Buthus martensi Karsch on nerve fibers of this scorpion.

A neurotoxin (BmK I) was purified from the venom of the scorpion species Buthus martensi Karsch. Effects of this toxin on the excitability of the abdominal nerve fibers of the same scorpion were examined. The toxin had no effect at all on the action and resting potentials recorded intracellularly even at a concentration as high as 100 microM. A similar result was obtained through optical measurements of the action potential using a potential sensitive dye. Sea anemone toxin II (8 microM) had no effect on nerve excitability either. However, tetrodotoxin (50 nM) reversibly suppressed the action potential and grayanotoxin II (20 microM) induced a sustained depolarization of the nerve membrane which resulted in a reversible suppression of the action potential. BmK I at a concentration of 0.1 microM greatly prolonged the action potential in the crayfish giant axon. We conclude that the Na channel of nerve fibers of this scorpion is totally insensitive to the neurotoxin in this scorpion's venom.

Animals↗
PubMed2005

Parasitism of bark scorpion Centruroides exilicauda (Scorpiones: Buthidae) by entomopathogenic nematodes (Rhabditida: Steinernematidae; Heterorhabditidae).

In laboratory bioassays, Steinernema glaseri Steiner, Steinernema riobrave Cabanillas, Poinar & Raulston, Heterorhabditis bacteriophora Poinar, and Heterorhabditis marelatus Liu & Berry were capable of infecting and killing the bark scorpion, Centruroides exilicauda (Wood). Steinernema feltiae (Filipjev) and Steinernema carpocapsae (Weiser) failed to infect C. exilicauda at 22 degrees C. S. glaseri, H. marelatus, and H. bacteriophora caused significant mortality at 22 degrees C, indicating the potential role of these parasites as a biocontrol option. Efficacy of S. glaseri and H. bacteriophora was reduced in an assay conducted at 25 degrees C. Only S. glaseri was able to reproduce in the target host. Dissection of scorpions at the end of the experimental periods revealed inactive juvenile S. riobrave, H. marelatus, and H. bacteriophora nematodes. Both mermithid and oxyurid nematodes have been documented as nematode parasites of scorpions, but rhabditids have not been reported until now. Field studies are warranted to assess the usefulness of entomopathogenic nematodes as biocontrol agents of bark scorpions.

Animals↗
PubMed1998

Second degree atrio-ventricular block and cardiotoxicity secondary to envenomation by the scorpion Leiurus quinquestriatus ('yellow scorpion')--an indication for serotherapy?

Tachyarrhythmia following scorpion envenomation might be an indication for anti venin therapy. We present a case of an unusual cardiotoxic response to Leiurus quinquestriatus ('yellow scorpion') venom-second degree atrio-ventricular block (Mobitz type 1). We review the biological activities of L. quinquestriatus' venom and the arrhythmia's possible pathophysiology. The question arising from this case is the therapeutic approach to cardiotoxicity and bradyarrhythmias induced by scorpion envenomation-mainly, the indication for anti serum therapy.

Adult↗
PubMed2001

A naturally occurring non-coding fusion transcript derived from scorpion venom gland: implication for the regulation of scorpion toxin gene expression.

Scorpion venom glands synthesize and secrete a great number of low molecular mass toxic peptides for prey and defense. Many cDNAs and genomic genes encoding these toxins have been isolated and sequenced. However, their expression regulation mechanism is not yet known at present. During screening of a cDNA library prepared from venom glands of the scorpion Buthus martensii Karsch, we isolated a natural fusion cDNA composed of the 5'-untranslated region (UTR) and upstream coding sequence of a long-chain toxin transcript and the downstream coding sequence and 3'-UTR of a short-chain toxin transcript. The junction site is just the overlapping region of 11 nucleotides (GGCAAGGAAAT) between the two wild transcripts, and thus leads to the formation of an early stop codon, which will cause premature translation. Based on the above observations, combined with the genomic data, we proposed a characteristic regulation mechanism of scorpion toxin genes, in which trans-splicing and nonsense mediated mRNA decay are involved.

3' Untranslated Regions↗
PubMed1993

Scorpionism in South Africa. A report of 42 serious scorpion envenomations.

Forty-two cases of serious scorpion envenomation, of which 4 had a fatal outcome, are presented. The clinical profile, differential diagnosis and management of scorpionism are discussed. Most envenomations occurred in the summer months, peaking in January and February. An immediate local burning pain was the most prominent symptom. Systemic symptoms and signs developed within 4 hours of the sting in most instances, characterised by general paraesthesia, hyperaesthesia, muscle pain and cramps. Other striking features included dysphagia, dysarthria and sialorrhoea with varying degrees of loss of pharyngeal reflexes. The blood pressure and the temperature were often raised and the tendon reflexes increased, while motor power was often impaired. In a considerable number of patients the course was complicated by varying degrees of respiratory dysfunction, which tended to be more serious in children. The oustanding feature in children was an extreme form of restlessness characterised by excessive neuromuscular activity. Victims of scorpion sting, particularly in high-risk localities, should be closely observed for 12-24 hours. Children and other high-risk patients should be hospitalised. All patients with symptoms and signs of systemic envenomation should receive antivenom. Parabuthus granulatus (Hemprich & Ehrenberg, 1828) has been identified as the most important venomous species in the western Cape. The antivenom is produced from the venom of the medically less important P. transvaalicus Purcell, 1899. A strong case can therefore be made for the inclusion of P. granulatus venom in the production of a polyvalent antivenom.

Adult↗
PubMed1988

[Scorpions and scorpion stings in Jordan].

The scorpion fauna of Jordan consists of fourteen species belonging to three families (Buthidae, Scorpionidae and Diplocentridae), of which three species are poisonous: Leiurus quinquestriatus, Adroctonus crassicauda and Buthus occitanus. A key to all species is included. Five hundred and forty-seven cases of scorpion stings were reported during 1982-1985, including two fatalities. Clinical data for sixteen cases treated at the Jordan University Hospital are summarized. In Jordan human and cultural customs are related to scorpion stings. Sting accidents according to age groups and seasons are given.

Adolescent↗
PubMed2005

Characterization of a novel cDNA encoding a short venom peptide derived from venom gland of scorpion Buthus martensii Karsch: trans-splicing may play an important role in the diversification of scorpion venom peptides.

A novel cDNA clone (named BmKT-u) which is a hybrid molecule of the 5'-terminal region of BmKT' cDNA and the 3'-terminal region of an undocumented cDNA (named BmKu), was isolated from a cDNA library made from the venom gland of scorpion Buthus martensii Karsch. BmKT-u codes for a 30 amino acid residue precursor peptide composed of a 20-residue signal sequence, and a putative 10-residue novel mature peptide. Northern blot hybridization showed BmKT-u cDNA is generated from a transcript. RT-PCR experiments excluded the possibility that BmKT-u cDNA is an artifact generated during reverse transcription. Genomic amplifications performed with three pairs of BmKT-u gene-specific primers showed the BmKT-u gene does not exist in the genome of the scorpion as a single transcriptional unit. Genomic cloning for BmKT' showed that the BmKT' gene contains an intron of 509 bp inserted into the region encoding the C-terminal region of the signal peptide. A sequence alignment comparison of the cDNA of BmKT-u with genomic BmKT' revealed that the junction site of the hybrid molecule is located at the 5'-splicing site of the intron. The data suggest that the BmKT-u transcript is a naturally occurring mature mRNA that is generated by trans-splicing. Trans-splicing may contribute to the diversity of venom peptides from venomous animals.

Amino Acid Sequence↗
PubMed2006

Serum levels of IL-6 and its soluble receptor, TNF-alpha and chemokine RANTES in scorpion envenomed children: their relation to scorpion envenomation outcome.

During the present study, 30 children in Upper Egypt (less than 12 years old) were admitted to Pediatric Intensive Care Unit because of scorpion envenomation. They were compared with 20 apparently normal children of matching age and sex as controls. The victims and controls were subjected to complete clinical examination and full blood picture. The serum levels of interleukin-6 (IL-6), soluble IL-6 receptor (sIL-6R), regulated upon activation normal T cells expressed and secreted (RANTES ) and tumour necrosis factor-alpha (TNF-alpha) were determined once for the controls and twice for the victims, the first sample on admission and the second sample after 24h. All victims showed significantly higher mean values of IL-6, sIL-6R, RANTES, TNF-alpha, and leucocytic count both on admission and on the follow up when compared with controls. According to the clinical manifestations of envenomation, 40% of the victims had a mild envenomation manifestation, while 60% of them had severe manifestations. The severely envenomed children showed significantly higher mean values of IL-6, sIL-6R, TNF-alpha, RANTES and leucocytic count both on admission and on the follow up samples when compared with the mild cases. The non-survival victims (five victims) showed significantly higher mean values of IL-6, sIL-6R, TNF-alpha, RANTES and leucocytic count both on admission and on the follow up samples in comparison to the survivals. Furthermore, those fatal cases showed a non-significant decline in the serum levels of IL-6, sIL-6R, TNF-alpha, RANTES and leucocytic count on the following up samples, while the survivals showed a significant decline in the serum levels of these parameters on the following up samples. In conclusion, these data revealed that IL-6, sIL-6R, TNF-alpha and chemokine, RANTES are involved in the pathogenesis of scorpion envenomation and correlated with its severity.

Animals↗
PubMed1978

Review of Southern African scorpions and scorpionism.

Medically important scorpions are discussed in terms of their venom, methods of envenomation and distribution in relation to the pattern of human population density dispersal. Notes on the treatment of scorpion sting and the identification of important species are provided.

Animals↗
PubMed2002

Characterization of scorpion alpha-like toxin group using two new toxins from the scorpion Leiurus quinquestriatus hebraeus.

Two novel toxins, Lqh6 and Lqh7, isolated from the venom of the scorpion Leiurus quinquestriatus hebraeus, have in their sequence a molecular signature (8Q/KPE10) associated with a recently defined group of alpha-toxins that target Na channels, namely the alpha-like toxins [reviewed in Gordon, D., Savarin, P., Gurevitz, M. & Zinn-Justin, S. (1998) J. Toxicol. Toxin Rev. 17, 131-159]. Lqh6 and Lqh7 are highly toxic to insects and mice, and inhibit the binding of alpha-toxins to cockroach neuronal membranes. Although they kill rodents by intracerebroventricular injection, they do not inhibit the binding of antimammal alpha-toxins (e.g. Lqh2) to rat brain synaptosomes, not even at high concentrations. Furthermore, in voltage-clamp experiments, rat brain Na channels IIA (rNav1.2A) expressed in Xenopus oocytes are not affected by Lqh6 nor by Lqh7 below 3 micro m. In contrast, muscular Na channels (rNav1.4 and hNav1.5) expressed in the same cells respond to nanomolar concentrations of Lqh6 and Lqh7 by slowing of Na current inactivation and a leftward shift of the peak conductance-voltage curve. The structural and pharmacological properties of the new toxins are compared to those of other scorpion alpha-toxins in order to re-examine the hallmarks previously set for the alpha-like toxin group.

Amino Acid Sequence↗
PubMedDate not supplied

[First record of scorpionism caused by Tityus adrianoi Lourenço (Scorpiones: Buthidae)].

Three cases of scorpionism caused by Tityus adrianoi Lourenço occurring in the cities of Belo Horizonte and Curvelo, Minas Gerais State, Brazil, are presented. The patients were treated on the same day as the accident and in all cases, only local pain was reported, which varied from low to intense, without posterior complications. All three cases were classified as mild.

Adult↗
PubMed1996

Solution structure of P01, a natural scorpion peptide structurally analogous to scorpion toxins specific for apamin-sensitive potassium channel.

The venom of the North African scorpion Androctonus mauretanicus mauretanicus possesses numerous highly active neurotoxins that specifically bind to various ion channels. One of these, P05, has been found to bind specifically to calcium-activated potassium channels and also to compete with apamin, a toxin extracted from bee venom. Besides the highly potent ones, several of these peptides (including that of P01) have been purified and been found to possess only a very weak, although significant, activity in competition with apamin. The amino acid sequence of P01 shows that it is shorter than P05 by two residues. This deletion occurs within an alpha-helix stretch (residues 5-12). This alpha-helix has been shown to be involved in the interaction of P05 with its receptor via two arginine residues. These two arginines are absent in the P01 sequence. Furthermore, a proline residue in position 7 of the P01 sequence may act as an alpha-helix breaker. We have determined the solution structure of P01 by conventional two-dimensional 1H nuclear magnetic resonance and show that 1) the proline residue does not disturb the alpha-helix running from residues 5 to 12; 2) the two arginines are topologically replaced by two acidic residues, which explains the drop in activity; 3) the residual binding activity may be due to the histidine residue in position 9; and 4) the overall secondary structure is conserved, i.e., an alpha-helix running from residues 5 to 12, two antiparallel stretches of beta-sheet (residues 15-20 and 23-27) connected by a type I' beta-turn, and three disulfide bridges connecting the alpha-helix to the beta-sheet.

Amino Acid Sequence↗
PubMed1999

An nmr conformational analysis of a synthetic peptide Cn2(1-15)NH2-S-S-acetyl-Cn2(52-66)NH2 from the New World Centruroides noxius 2 (Cn2) scorpion toxin: comparison of the structure with those of the Centruroides scorpion toxins.

The solution structure of a synthetic peptide, Cn2(1-15)NH2-S-S-acetyl-Cn2(52-66)NH2 from toxin 2 (Cn2) of the New World scorpion Centruroides noxius was determined using nmr and molecular dynamics calculations. The peptide has no significant secondary structure such as an alpha-helix or a beta-sheet, yet it has a fixed conformation for the first chain. The backbone secondary structure involving residues 6-12 in this peptide shows an excellent overlap with the structures of natural neurotoxins from Centruroides sculpturatus Ewing. Residues 6-9 form a distorted type I beta-turn and residues 10-12 form a gamma-turn. As residues 7-10 in the Centruroides toxins correspond to one of the regions of highest sequence variability, it may account for the species specificity and/or selectivity of toxic action. The conformation of this region evidently plays an important role in receptor recognition and in binding to the neutralizing monoclonal antibody BCF2 raised against the intact toxin.

Amino Acid Sequence↗
PubMed2001

Egg maturation and parthenogenetic recovery of diploidy in the scorpion Liocheles australasiae (Fabricius) (Scorpions, ischnuridae).

In the scorpion Liocheles australasiae, egg maturation and parthenogenetic recoveries of chromosome number and nuclear DNA content were examined by histological, karyological observations and quantitative measurements of DNA. The primary oocyte becomes mature through two successive maturation divisions. The first maturation division takes place in the primary oocyte to produce a secondary oocyte and a first polar body. The second maturation division soon occurs in the secondary oocyte, in which the nucleus is divided into a mature egg nucleus and a second polar body nucleus, not followed by cytoplasmic fission. The first polar body, in one case, was successively divided into two second polar bodies; in the other case it was not divided. In either case, these polar bodies remained attached to the early embryo. The fate of these polar bodies during further embryogenesis were studied. In the karyological analysis, the chromosome number was divided into two groups, one from 27-32, the other was 54-64. The former was presumably the metaphase chromosome number at the meiotic division; the latter was presumably the metaphase chromosome number at the mitotic division. DNA content in the diploid nucleus of the primary oocyte, doubled before the maturation divisions, was reduced through the maturation divisions by one-half in the nuclei of the secondary oocyte and the first polar body and by one-fourth in the nuclei of the egg and the second polar bodies. The first reduction of DNA content corresponded to halving the number of the chromosomes in the first maturation division and the second to the nuclear division in the secondary oocyte. These reductions represent a common process of egg maturation, except the final production of the mature egg with two haploid nuclei, an egg nucleus, and a second polar body nucleus. These two nuclei, which were formed apart in the mature egg, drew near to fuse into a zygote nucleus. The chromosome number and nuclear DNA content were doubled in the zygote and each blastomere in embryos, supporting the hypothesis that the egg nucleus fuses with the second polar body nucleus and this conjugation initiates subsequent embryonic development.

Animals↗
PubMed1992

The amino acid sequence of toxin IV from the Androctonus australis scorpion: differing effects of natural mutations in scorpion alpha-toxins on their antigenic and toxic properties.

The complete amino acid sequence (64 residues) of the AaH IV toxin from the scorpion Androctonus australis Hector was determined by automated Edman degradation and was compared with the sequences of other Androctonus toxins. AaH IV was also tested by radioimmunoassay for binding to antisera raised against other toxins of the same species. The results indicated that AaH IV shares some of the antigenic properties of AaH I and AaH III toxins, but does not cross-react with anti-AaH II antibodies. The structural basis for the observed antigenic relationships can be found in the high degree of homology displayed by AaH IV with regard to AaH I and III, the changes in amino acid residues equally affecting regions included or excluded from the main predicted antigenic sites of AaH IV. The lower biological potency of AaH IV is presumably the result of some of the sequence differences. In particular, substitution affecting the charge and bulkiness of residue 61 could account for the poor receptor binding and consequential weak toxic properties of this molecule.

Amino Acid Sequence↗
PubMed2004

Comparison of a 3D-model of the classical alpha-scorpion toxin V from Leiurus quinquestriatus quinquestriatus with other scorpion toxins.

In the present paper, a study of classical and insect alpha-scorpion toxins is described. A homology model of the classical alpha-toxin LqqV from Leiurus quinquestriatus quinquestriatus was developed. The model was compared to stable and energetically favourable conformations of AaHII from Androctonus australis Hector and LqhalphaIT from Leiurus quinquestriatus hebraeus, which are the most active alpha-toxins in mammals and insects. The conformations were retrieved from molecular dynamics simulations of known structures. The model of LqqV shows a C-terminal conformation similar to LqhalphaIT. This is mainly caused by electrostatic interactions between Lys10 /Lys60 and Glu59, which are comparable to the cation-pi interactions of Tyr10 and Arg64 in LqhalphaIT. During the simulations the structures of AaHII and LqqV were stabilised through electrostatic interactions between Glu32 and Lys50 and especially the loop adjacent to the alpha-helix is affected, which is in contrast to LqhalphaIT. When the molecular electrostatic potentials of the toxins were studied, a possibly important difference between the classical alpha-toxins and the insect alpha-toxin LqhalphaIT was found in the area around Lys30 and Arg56 of AaHII, where a positive potential is missing in LqhalphaIT. A large negative potential caused by Asp3, Glu15 and Asp19 in LqhalphaIT is also unique for this toxin. It is proposed that Arg18, which is important for activity of LqhalphaIT, restricts the negative potential in this area and is not essential for toxins where negatively charged residues in comparable positions are not present.

Amino Acid Sequence↗