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PubMed2003

Molecular cloning and nucleotide sequence analysis of encoded anti-insect toxin BotIT2 from the scorpion Buthus occitanus tunetanus venom.

Numerous toxins from scorpion venoms are much more toxic to insects than to other animal classes, and possess high affinity to Na+ channels. Many of them active on insects were purified from the venom of Buthus occitanus tunetanus. Using amino acid sequences of BotIT2 and RACE-PCR amplification (Rapid amplification of cDNA ends) technique, we isolated, identified and sequenced the nucleotide sequence from the venom glands of the scorpion Buthus occitanus tunetanus. The cDNA encodes a precursor of an insect toxin of 60 amino acid residues. The deduced nucleotide sequence toxin was identical to the determined amino acid sequence of BotIT2. BotIT2 is more similar to the excitatory toxins in its mode of action and to the depressant toxins in its primary structure.

Amino Acid Sequence↗
PubMed2006

Cerebrovascular manifestations in scorpion sting: a case series.

Cerebrovascular manifestations are uncommon presentations of scorpion sting in the Indian subcontinent. A prospective study was carried out on 50 patients with scorpion sting referred to the Government General Hospital during the period from April 2004 to March 2005. In all the patients, detailed history, physical examination with a specific neurological examination and routine biochemical testing and fundus examination were done. Computerized Tomography (CT) and Magnetic Resonance Imaging (MRI) were done in cases with neurological deficit. All these patients also underwent a complete hematological, rheumatologic and cardiovascular work-up for stroke. Cerebrovascular involvement was noted in four patients (8%). Hemorrhagic stroke was noted in two patients (4%) and thrombotic stroke was noted in two patients (4%). The mean time of presentation of neurological symptoms was 2 days. Stroke has been a common presentation in our series (8%). Contrary to world literature, there have been no reports of cranial nerve palsies or neuromuscular involvement in our series.

Adolescent↗
PubMed2006

[Snakes, scorpions and other poisonous creatures: prophylaxis and emergency medicine].

Most cases of poisoning by animals are caused by snakes, spiders or scorpions. In addition to"first aid" such as calming the victim and immobilization of the bitten limb, other measures include monitoring vital functions and rapid transportation to hospital as dictated by the symptoms presenting, and, where indicated, injection of an antiserum (identification of the animal concerned). On no account should the bite wound be cut or attempts made to suck out the venom. While the sting of a scorpion or a spider bite often do not lead to severe complications in adults, a brush with a poisonous snake may be much more serious.

Adult↗
PubMed2006

A study on venom proteins of Iurus dufoureius asiaticus Birula, 1903 (Scorpiones: Iuridae).

The scorpion Iurus dufoureius asiaticus (Birula 1903) which is the largest scorpion in Europe and Turkey belongs to the family Iuridae and is endemic in Turkey. No data has been found about the venom components of I. d. asiaticus. In this study, the venom extract ob-tained from I. d. asiaticus specimens collected from Aydin were analyzed using the Tris tricine SDS-PAGE method. A total of 28 protein fractions or fraction groups were detected in the range of 6.5-205 kDa.

Animals↗
PubMed1991

[Myocardial and central nervous system involvement in scorpion envenomation by Androctonus bicolor bicolor].

A 3-year-old girl was stung by a scorpion (Androctonus bicolor bicolor) in her foot while walking barefoot in a courtyard in the early evening. Within an hour she began to vomit and became extremely agitated. On admission she was stuporous and hypotensive, and severe hypertonicity and prolonged convulsions ensued. Treatment consisted of adrenalin, corticosteroids, diazepam, chloral hydrate and phenobarbital and she improved within 2 hours. The following day myocardial involvement, with tachycardia, gallop rhythm and electrocardiographic abnormalities developed and treatment with digoxin and dexamethasone was started. Full recovery took 6 days. Both black and brown scorpions of this species are dangerous and may cause multisystem manifestations, especially in young children. Usually found in the desert or in sand dunes, it sometimes occurs in inhabited areas as well, in rubble or building ruins. Its distribution is from Haifa in the north down to the Sinai peninsula.

Animals↗
PubMed1983

Scorpion sting producing severe muscular paralysis. A case report.

A case of scorpion (Parabuthus species) envenomation causing severe respiratory failure is presented. Systemic effects, which included muscular weakness, hypertonus and bulbar dysfunction, developed 8 hours after poisoning; this emphasizes the importance of close observation of victims of envenomation. Treatment included the administration of scorpion antivenom (SAIMR) and mechanical ventilation for 4 days.

Adolescent↗
PubMed1995

Scorpion envenomation in children in southern India.

The clinical presentation of 32 children with scorpion envenomation was analysed. The most common presentation was cold, clammy extremities with normal blood pressure. Myocarditis was present in 16 children (50%) and encephalopathy in four (12.5%). Two children died. ECG was a sensitive indicator of myocarditis which was subclinical in four children. Left ventricular dysfunction was a transient phenomenon. Myocarditis and encephalopathy were the two lethal complications observed. Serum free fatty acid levels were elevated two to three-fold in all symptomatic patients. Blood glucose levels were only mildly elevated and serum amylase levels and electrolytes were normal in all the children. No specific antivenom was given. In the absence of specific antivenom, early and active supportive treatment reduces the morbidity and mortality due to scorpion envenomation.

Animals↗
PubMed1993

Stroke following scorpion sting.

A 30 year old male presented with crossed buccofacial apraxia, apraxia for speech, Left UMN facial palsy and hemiplegia following scorpion sting. A cerebrovascular accident can develop following a scorpion sting due to venom-induced cerebral thrombosis.

Adult↗
PubMed1997

Solution structure of maurotoxin, a scorpion toxin from Scorpio maurus, with high affinity for voltage-gated potassium channels.

Maurotoxin (MTX), purified from the scorpionid Scorpio maurus is a potent ligand for potassium channels. It shows a broad specificity as being active on Kv1.1 (Kd = 37 nM), Kv1.2 (Kd = 0.8 nM), Kv1.3 (Kd = 150 nM) voltage-gated potassium channels, as well as on small-conductance calcium-activated potassium channels. It has a unique disulfide pairing among the scorpion toxins family. The solution structure of MTX has been determined by 2D-NMR techniques, which led to the full description of its 3D conformation: a bended helix from residues 6 to 16 connected by a loop to a two-stranded antiparallel beta sheet (residues 23 to 26 and 28 to 31). The interaction of MTX with the pore region of the Kv1.2 potassium channel has been modeled according to their charge anisotropy. The structure of MTX is similar to other short scorpion toxins despite its peculiar disulfide pairing. Its interaction with the Kv1.2 channel involves a dipole moment, which guides and orients the toxin onto the pore, toward the binding site, and which thus is responsible for the specificity.

Amino Acid Sequence↗
PubMed1998

[Scorpion toxins and defensins].

The scorpion venoms possess many neurotoxic peptides which constitute a group of molecular families with a common architecture and a high degree of polymorphism. This architecture is found also in circulating antimicrobial peptides belonging to the defensins family, which are especially structurally related to the blocking potassium channels neurotoxins. The diversification in functions with a unique architectural scheme is discussed taking in account the biophysiological characteristics of the scorpion order.

Animals↗
PubMed1976

Experimental studies on the aetiology of acute scorpion pancreatitis.

This study examined the action of the venom of the scorpion Tityus trintatis on the pancreas and gastrointestinal tract in anaesthetized dogs, on the isolated extracorporeal haemoperfused canine pancreas and on the isolated canine sphincter of Oddi. The venom induces exocrine secretion in both the isolated and intact pancreas and causes contraction of the isolated sphincter of Oddi. These results are discussed in relation to the pathogenesis of acute scorpion pancreatitis and possibly of some other forms of acute pancreatitis.

Acute Disease↗
PubMed2002

Electrophysiological analysis of synaptic interactions within peg sensilla of scorpion pectines.

Pectines are unique, midventral sensory appendages that help direct mating and food-finding behaviors in scorpions. Dense two-dimensional arrays of bimodally sensitive (chemical and mechanical) peg sensilla form the primary sensory structures on pectines. Several qualities of peg sensilla make them well suited to electrophysiological investigation, including accessibility, stability of extracellular recordings, and the ease with which spiking cells can be identified and categorized. Cross-correlations of spontaneous neural activity show signs of synaptic interactions between sensillar neurons in all species examined to date (Paruroctonus mesaensis, Hadrurus arizonensis, Centruroides vittatus) representing three families and two superfamilies. Both excitatory and inhibitory interactions have been observed, as well as possible dyadic synaptic arrangement. Computer simulations of cross-correlograms are consistent with experimental data and may help provide additional insight into functionality of synaptic connections. Intra-sensillar interactions, coupled with the topographic order of peg sensilla and their central nervous system projections, may allow scorpions to precisely resolve microfeatures of chemical stimuli. Future research directions include inter-sensillar recordings to determine whether synaptic interactions extend between adjacent sensilla. Other unresolved questions that can be approached electrophysiologically are whether mechanosensory cells interact with chemosensitive cells and how the synaptic circuits function under specific chemical and mechanical stimulation.

Animals↗
PubMedDate not supplied

Unique interaction of scorpion toxins with the hERG channel.

ERG potassium channels specify one component of the delayed rectifier in the heart and are likely to play an important functional role in other excitable cells. Compared to other K+ channels, the human ERG (hERG) channel possesses an unusually long S5-P linker that presumably forms an alpha-helix important for channel function. hERG-specific toxins bind to the outer mouth of the hERG channel. Channel residues in the middle of the S5-P linker and at the pore entrance are critical for toxin binding. One of these scorpion toxins is BeKm-1. Residues critical for BeKm-1 binding to the hERG channel are located in the alpha-helix and the following loop, whereas the "traditional" interaction surface of other short scorpion toxins is formed by residues on the beta-sheet. This unique localization of BeKm-1's interaction surface and its specific action on the hERG channel suggest a unique outer mouth structure of the hERG channel. We used the mutant cycle analysis approach to define contacts in the toxin-channel complex. This information provides critical constraints and is important for molecular modeling of the hERG pore structure.

Animals↗
PubMed1993

Characterization of toxin III of the scorpion Leiurus quinquestriatus quinquestriatus: a new type of alpha-toxin highly toxic both to mammals and insects.

The primary structure of toxin III of Leiurus quinquestriatus quinquestriatus (Lqq III) was elucidated by automatic Edman degradation of the reduced and S-carboxymethylated protein and derived tryptic peptides. Like other scorpion toxins that are active on sodium channels, Lqq III, consisting of 64 amino acids, is a 7 kDa single-chain polypeptide crosslinked by four disulfide bridges. It belongs to the alpha-toxin group, as judged by competition experiments with 125I AaH II for binding to rat brain synaptosomes (K0.5 = 7 x 10(-7) M). Lqq III is the first alpha-toxin to be characterized that is highly toxic to mice [LD50 = 50 micrograms (7.1 nmol)/kg body wt], by subcutaneous injection, insects Blatella germanica [LD50 = 60 ng (8.5 pmol)/g body wt.] and Musca domestica [LD50 = 120 ng (17 pmol)/g body wt]. When tested via the intracerebroventricular route, the toxicity for mice [55 micrograms (8 nmol)/kg] was of the same order as that found by subcutaneous injection, indicating that Lqq III has a higher affinity for peripheral sodium channels that for those of the central nervous system. There are three differences between the sequences of Lqq III and Lqh alpha IT, an alpha-toxin isolated from the venom of Leiurus quinquestriatus hebraeus. These substitutions are found at positions 20, 24, and 64 (Ser-->Ala,Asp-->Glu and His-->Arg, respectively). Surprisingly Lqh alpha IT is only weakly active in mice [LD50 = 5 mg (0.7 mumol)/kg], while in insects its toxicity is similar to that of Lqq III [140 ng (20 pmol)/g body wt blowfly larvae]. These observations are relevant to the definition of scorpion toxin structure-activity relationships.

Amino Acid Sequence↗
PubMed2006

Role of disulfide bonds in modulating internal motions of proteins to tune their function: molecular dynamics simulation of scorpion toxin Lqh III.

A series of 1-ns MD simulations were performed on the scorpion toxin Lqh III in native and disulfide bond broken states. The removal of disulfide bonds has caused hydrogen bond network alteration in the five-residue turn, the long loop, the alpha-helix, the loop connecting strands II and III, and the C-terminal region. In addition and more importantly, it has influenced the amplitude of the fluctuations of five-residue turn, loops, and C-terminal region with a minor effect on the fluctuations of the cysteines in the broken bond sites. These findings suggest that disulfide bonds are not the most important factors in rigidifying their own locations, while they have more important effects at a global scale. Furthermore, our results reveal that disulfide bonds have considerable influence on the functionally important essential modes of motions and the correlations between the motions of the binding site residues. Therefore, we can conclude that disulfide bonds have a crucial role in modulating the function via adjusting the dynamics of scorpion toxin molecules. Although this conclusion cannot be generalized to all peptides and proteins, it demonstrates the importance of more investigations on this aspect of disulfide bond efficacy.

Animals↗
PubMed1998

Effect of some variables on the in vivo determination of scorpion and viper venom toxicities.

An adequate assessment of scorpion and snake venom LD50 is an important step for accurate evaluation of antivenom sera potencies and the optimization of serotherapy. The LD50 variation of Tunisian scorpion (Androctonus australis garzonii: Aag and Buthus occitanus tunetanus: Bot) venoms with body weight, sex and strain (Swiss or C57BI/6) of mice used, the route of venom injection, the venom-milking procedures (manually or electrically) and the venom batches have been studied over a 7-year period (1990-1996). Aag venom is 3-4 times more toxic than Bot venom. However for both venoms, the LD50 determined in C57BI/6 mice, in small body weight animal or by intraperitoneal route were respectively significantly lower than those determined in Swiss mice, in high body weight or by subcutaneous route. Significant LD50 variations (25-50%) were also seen from one electrically prepared batch to another. A good correlation (r = 0.982) was observed between the concentrations of the crude venom toxic fraction determined by ELISA and LD50 values when assessed in vivo. The LD50 variation of Tunisian viper (Cerastes cerastes: Cc and Vipera lebetina: VI) venoms with the strain (Swiss or BALB/c), sex and body weight of mice used, the season and the year of venom milking were also investigated over a 3-year period (1990-1992). No significant LD50 variations were observed with the mouse strain, the sex or the season of venom milking. However, LD50 varies significantly with the year of the venom collection and the body weight of mice used. Furthermore, SDS-PAGE analysis shows annual variation for VI venom composition where no such variations were observed for Cc venom. These results stress the need either for the standardization of the venom LD50 evaluation or of the venom quality used for the development of an efficient antivenom.

Animals↗
PubMed1994

Crystal structure of toxin II from the scorpion Androctonus australis Hector refined at 1.3 A resolution.

The crystal structure of toxin II from the scorpion Androctonus australis Hector has been refined at 1.3 A resolution using restrained least-squares methods. The final R-factor is 0.148 for the 13,619 reflections between 7.0 A and 1.3 A resolution with F > 2.5 sigma (F) and the bond length standard deviation from ideality is 0.017 A. Although minor changes have been introduced relative to the model previously refined at 1.8 A resolution, the use of higher-resolution data has allowed the modelling of some discrete disorder. Thus, three residues (including a disulphide bridge) have been built with multiple conformations. Occupancies were refined for the 106 solvent molecules included in the model, nine of them with explicit multiple sites. There is well-defined electron density for some of the protein hydrogen atoms in the final difference Fourier map. A detailed description of the toxin structure is presented, along with a comparison with the high-resolution structure of the related variant-3 scorpion toxin.

Amino Acid Sequence↗
PubMed1983

Cytophysiological aspects of digestion and storage in the liver of a scorpion, Androctonus australis (Arachnida).

The liver of a scorpion, Androctonus australis (Arachnida), was examined electron-microscopically and cytochemically, emphasizing correlations between structure, cytochemistry and physiology. The liver consists of digestive diverticula and interstitial tissue. Digestive diverticula are composed of basophilic cells and digestive cells. Basophilic cells produce exoenzymes. Digestive cells ensure intracellular digestion of nutrients absorbed by pinocytosis and store glycogen, lipids and mineral salts; the wastes of the digestive process (guanine, uric acid, mineral elements, pigments) are concentrated in "brown body vacuoles" which are ejected into the lumen of the diverticula. The interstitial tissue stores glycogen and lipids; it contains many lysosome-like organelles rich in iron. Fasting induces a decrease of the ratio of the volume of the diverticula to that of the interstitial tissue, a slow disappearance of the reserves in both diverticula and interstitial tissue, an increase of synthesis in the basophilic cells, and a decrease of the number of vacuoles in the digestive cells. The digestive mode of the scorpions associates a primitive intracellular process with an advanced extracellular process. The interstitial tissue can be considered as homologous to the adipose tissue of insects and myriapods, although it is devoid of urate cells. The excretion of guanine and uric acid has a peculiar meaning, because these purine wastes do not come from endogenous catabolism.

Animals↗