Phylogenetic and Morphological Analyses of Androctonus crassicuda from Khuzestan Province, Iran (Scorpiones: Buthidae)

The Androctonus crassicuda is the most diverse scorpion species in the family of Buthidae, which is endemic to Khuzestan province, Iran. Investigation of the relationship of species by means of a molecular study of specimens is one of the new approaches due to the limitations of the morphological approaches. In the current study, the analysis was based on 32 morphological characteristics of A. crassicuda native to southwest Iran. Moreover, the DNA sequencing of two mitochondrial markers, namely cytochrome oxidase subunit I and 12sRNA loci was performed, and the phylogenetic tree was constructed using maximum likelihood method with 1000 replications using MEGA software (version 7). Based on the results of the phylogenetic tree, A. crassicuda was classified into a monophyletic group. However, the genetic diversity of this species populations was not significant (0.001). The highest and lowest genetic distance of A. crassicuda was compared with the reports obtained in Urmia and west Azerbaijan, Iran. There was a clear divergence between the A. crassicuda isolated from northern and southern areas of Iran. This study showed the importance of geographical and climate features of the region and genetic distance among the populations. The phylogenetic analysis of Androctonus species from other regions showed the highest and lowest genetic distance with A. gonneti (Morocco) and A. amoreuxi (Portugal), respectively. The comparison of the morphological characteristics and morphometric results revealed that metasoma characteristics are important in the identification of A. crassicuda. The results of the analysis of the morphometric values of A. crassicuda were mainly compatible with the phylogenetic trees and supported the traditional morphological classification, thereby presenting a clearly definition of the genera of Androctonus species.

Antigenic and Substrate Preference Differences between Scorpion and Spider Dermonecrotic Toxins, a Comparative Investigation

The Hemiscorpius lepturus scorpion and brown spider Loxosceles intermedia represent a public health problem in Asia and America, respectively. Although distinct, these organisms contain similar toxins responsible for the principal clinical signs of envenomation. To better understand the properties of these toxins, we designed a study to compare recombinant Heminecrolysin (rHNC) and rLiD1, the major phospholipase D toxins of scorpion and spider venom, respectively. Using a competitive ELISA and a hemolytic inhibition test, we come to spot a cross reaction between scorpion and spider venoms along with an epitopic similarity between rHNC and rLiD1 associated with neutralizing antibodies. Results show that the ability of the rHNC to hydrolyze lysophosphatidylcholine (LPC) is equivalent to that of rLiD1 to hydrolyze sphingomyelin and vice-versa. rHNC exclusively catalyze transphosphatidylation of LPC producing cyclic phosphatidic acid (cPA). The in-silico analysis of hydrogen bonds between LPC and toxins provides a possible explanation for the higher transphosphatidylase activity of rHNC. Interestingly, for the first time, we reveal that lysophosphatidic acid (LPA) can be a substrate for both enzymes using cellular and enzymatic assays. The finding of the usage of LPA as a substrate as well as the formation of cPA as an end product could shed more light on the molecular basis of Hemiscorpius lepturus envenomation as well as on loxoscelism.

The Dual α-Amidation System in Scorpion Venom Glands

Many peptides in scorpion venoms are amidated at their C-termini. This post-translational modification is paramount for the correct biological function of ion channel toxins and antimicrobial peptides, among others. The discovery of canonical amidation sequences in transcriptome-derived scorpion proproteins suggests that a conserved enzymatic α-amidation system must be responsible for this modification of scorpion peptides. A transcriptomic approach was employed to identify sequences putatively encoding enzymes of the α-amidation pathway. A dual enzymatic α-amidation system was found, consisting of the membrane-anchored, bifunctional, peptidylglycine α-amidating monooxygenase (PAM) and its paralogs, soluble monofunctional peptidylglycine α-hydroxylating monooxygenase (PHMm) and peptidyl-α-hydroxyglycine α-amidating lyase (PALm). Independent genes encode these three enzymes. Amino acid residues responsible for ion coordination and enzymatic activity are conserved in these sequences, suggesting that the enzymes are functional. Potential endoproteolytic recognition sites for proprotein convertases in the PAM sequence indicate that PAM-derived soluble isoforms may also be expressed. Sequences potentially encoding proprotein convertases (PC1 and PC2), carboxypeptidase E (CPE), and other enzymes of the α-amidation pathway, were also found, confirming the presence of this pathway in scorpions.

[Identification of Scolopendra subspinipes mutilans and its adulterants using DNA barcode]

In this study, the COI barcode was used to identify the Scolopendra medicinal materials and its adulterants in order to provide a new method for the identification of Scolopendra. Genomic DNA was extracted from the experimental samples. The COI sequences were amplified and sequenced bi-directionally. Sequence alignment and NJ tree construction was carried out by MEGA6.0 software. The results showed that the COI sequences can be obtained from all experimental samples. The average inter-specific K2P distance of Scolopendra was 0.222 and the minimum inter-specific distance was 0.190. All the Scolopendra subspinipes mutilans medicinal samples clustered into a clade in the NJ tree and can be distinguished from its adulterants. In a conclusion, COI can be used to correctly identify Scolopendra medicinal materials, and it will be a potential DNA barcode for identifying other animal medicinal materials.

Digestive amylase of a primitive animal, the scorpion: purification and biochemical characterization

Scorpion, one of the most ancient invertebrates was chosen, as a model of a primitive animal, to purify and characterize an amylase located in the hepatopancreas. The scorpion digestive amylase (SDA) was purified. Pure SDA was obtained after heat treatment followed by ammonium sulfate fractionation and three steps of chromatography. The pure amylase is not glycosylated and has a molecular mass of 59,101 Da determined by MALDI-TOF MS analysis. The maximal amylase activity was measured at pH 7.0 and 50 degrees C, in the presence of Ca2+ and using potato starch as substrate. The enzyme was able to hydrolyze also, glycogen and amylose. The 23 NH2-terminal amino acid SDA residues were sequenced. The sequence obtained is similar to those of mammalian and avian pancreatic amylases. Nevertheless, polyclonal antibodies directed against SDA failed to recognize classical digestive amylases like the porcine pancreatic one.

Cloning, sequence analysis and homology modeling of a novel phospholipase A2 from Heterometrus fulvipes (Indian black scorpion)

We report the cloning and sequencing of group III phospholipaseA(2) from Heterometrus fulvipes (HfPLA(2)), Indian black scorpion. The cDNA sequence codes for the mature portion of the group PLA(2) of 103 amino acids. The sequence has 85% identity with Mesobuthus tamulus (Indian red scorpion) PLA(2) and a 40% identity with bee venom PLA(2) and human group III PLA(2). Most of the essential features of group III PLA(2) like Ca(2+) binding loop and catalytic residues are conserved. Homology modeling was done with the known structure of group III bee venom PLA(2). All the secondary structural motifs and the disulfide bridges are as predicted. The variation like the replacement of aspartic acid residue with glutamic acid in the well known histidine-aspartic acid dyad is a rare feature. This is the first structural model report of an Indian black scorpion PLA(2).

Sequence analysis and phylogenetic relationship of genes encoding heterodimeric phospholipases A2 from the venom of the scorpion Anuroctonus phaiodactylus

Some scorpion venom contain heterodimeric phospholipases A2. They were shown to be toxic to insects and to cause edema and/or hemolysis of mammalian erythrocytes. This manuscript describes the results of cDNA cloning of five different heterodimeric phospholipases from the venomous glands of the Mexican scorpion Anuroctonus phaiodactylus. The amino acid sequence deduced from the heterodimeric phospholipases open reading frames corresponds in each case to a different isoform. The nucleotide sequences corresponding to two of these genes were also obtained by directly sequencing genomic DNA. The cDNA isoforms show high similarity with the heterodimeric phospholipase Phaiodactylipin purified from the same scorpion. However, similar phospholipases were also found in scorpions from other species and the sequences available were used to construct a phylogenetic tree. In order to understand better the gene structure and phylogeny of these enzymes we analyzed their sequences and compared them with secretory phospholipases of other sources from groups I, II and III. The genomic DNA sequence of a similar phospholipase from bee venomous glands was also cloned. The information available on a Drosophila phospholipase was included in this analysis. The phospholipases of groups I and II contain a conserved exon-intron structure (four or five exons of the mature segment of the enzyme are separated by three or four introns). Also, the gene structure of the phospholipases from A. phaiodactylus and that of the bee venom, belonging to group III phospholipases, are interrupted by three introns. The mature peptide of the bee enzyme is a single polypeptide chain, coded by four exons, whereas those from the scorpion studied here although having four exons, showed the presence of two different polypeptides in its native state. The mature protein is processed after synthesis, producing the heterodimeric structure: a long and a short-peptide chain, linked by a disulfide bridge. The small subunit is the one coded by the fourth exon. The human phospholipase A2 and that of Drosophila, also classified into the group III phospholipases, have a considerably different exon-intron organization.

Scorpion digestive lipase: A member of a new invertebrate's lipase group presenting novel characteristics

Unlike classical digestive lipases, the scorpion digestive lipase (SDL) has a strong basic character. The SDL activity's optimal pH, when using tributyrin or olive oil as substrate, was 9.0. Added to that, the estimated isoelectric point of the native SDL using the electrofocusing technique, was found to be higher than 9.6. To our knowledge, this is the first report of an animal digestive lipase having such a basic character. When olive oil was used as substrate, SDL was shown to be insensitive to the presence of amphiphilic proteins such as bovine serum albumin (BSA). Furthermore, the hydrolysis was found to be specifically dependent on the presence of Ca(2+) ions, since no significant SDL activity was detected in the presence of ions chelator such as EDTA. Nevertheless, the SDL does not require Ca(2+) to trigger the hydrolysis of tributyrin emulsion. Interestingly Zn(2+) and Cu(2+) ions act as strong inhibitors of SDL activity when using tributyrin as substrate. An internal chymotryptic cleavage of SDL generated two fragments of 28 and 25 kDa having the same N-terminal sequence. This sequence of 19 residues does not share any homology with known animal and microbial lipases. Polyclonal antibodies directed against SDL (pAbs anti-SDL) failed to recognise ostrich pancreatic and dog gastric lipases (OPL and rDGL). Moreover, both pAbs anti-OPL and anti-rDGL failed to immunoreact with SDL. These immunological as well as distinct biochemical properties strengthen the idea that SDL appears to belong to a new invertebrate's lipase group.

Immunocytochemical localization of scorpion digestive lipase

The scorpion hepatopancreas consists of digestive diverticula and interstitial tissue. A digestive diverticulum is composed of two differentiated cell types: the secretory zymogene-like cells and the digestive cells which are the most abundant. The scorpion digestive lipase (SDL) has been previously purified from scorpion hepatopancreas, but its cellular localization has not yet been established. Polyclonal antibodies specific to SDL were prepared and used in immunofluorescence and immunogold techniques to determine the cellular location of SDL. Our results clearly established that SDL was detected intracellularly in specific vesicles tentatively named (SDL+) granules of the digestive cells. No immunolabelling was observed in secretory zymogene-like cells. This immunocytolocalization indicates that lipid digestion might occur in specific granules inside the digestive cells, as suggested by previous studies on the scorpion digestive process.

Purification and properties of hyaluronidase from Palamneus gravimanus (Indian black scorpion) venom

Scorpion venoms are a rich source of enzymes. Some of the enzymes such as phospholipase A2, proteolytic enzymes and phosphodiesterase are well characterized. However, hyaluronidase has not been studied extensively. In this paper we describe the purification and characterization of hyaluronidase (Hyaluronate lyase, E.C.3.2.1.35) from the Palamneus gravimanus scorpion venom by a combination of gel filtration on Sephadex G-75 and ion-exchange chromatography on DEAE-cellulose. The optimal pH and temperature for its maximum activity of the isolated enzyme were 4.5 and 37 degrees C, respectively, and its K(m) was 47.61 microg/ml at 37 degrees C and its specific activity was 6411.7 +/- 117TRU/min per mg against 250 +/- 4.0 TRU/min per mg for the whole desiccated venom suggesting 25-fold purification. The molecular weight of the isolated enzyme was 52 +/- 1 kDa as estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and gel filtration chromatography on Sephadex G-75. The enzyme was stable for 30 days in the presence of NaCl; no loss of activity was observed up to 37 degrees degrees C and showed a sharp decrease in its activity at 40 degrees C. Heparin inhibited the enzyme activity.

ANEPIII, a new recombinant neurotoxic polypeptide derived from scorpion peptide, inhibits delayed rectifier, but not A-type potassium currents in rat primary cultured hippocampal and cortical neurons

A new recombinant neurotoxic polypeptide ANEPIII (BmK ANEPIII) derived from Scorpion peptide, which was demonstrated with antineuroexcitation properties in animal models, was examined for its action on K+ currents in primary cultured rat hippocampal and cortical neurons using the patch clamp technique in the whole-cell configuration. The delayed rectifier K+ current (I(k)) was inhibited by externally applied recombinant BmK ANEPIII, while the transient A-current (I(A)) remained virtually unaffected. BmK ANEPIII 3 microM, reduced the delayed rectifier current by 28.2% and 23.6% in cultured rat hippocampal and cortical neurons, respectively. The concentration of half-maximal block was 155.1 nM for hippocampal neurons and 227.2 nM for cortical neurons, respectively. These results suggest that BmK ANEPIII affect K+ currents, which may lead to a reduction in neuronal excitability.

Purification and characterization of a novel lipase from the digestive glands of a primitive animal: The scorpion

Higher animal's lipases are well characterized, however, much less is known about lipases from primitive ones. We choose the scorpion, one of the most ancient invertebrates, as a model of a primitive animal. A lipolytic activity was located in the scorpion digestive glands, from which a scorpion digestive lipase (SDL) was purified. Pure SDL, a glycosylated protein, has a molecular mass of 50 kDa, it presents the interfacial activation phenomenon. It was found to be more active on short-chain triacylglycerols than on long-chain triacylglycerols. SDL is a serine enzyme and possesses one accessible sulfhydryl group which is not essential for the catalysis. Among the NH2-terminal 33 residues, a 17 amino acids sequence shows similarities with sequence of Drosophila melanogaster putative lipase. Interestingly, neither colipase, nor bile salts were detected in the scorpion hepatopancreas. This indicates that colipase evolved in vertebrates simultaneously with the appearance of an exocrine pancreas and a true liver which produces bile salts. Furthermore, polyclonal antibodies directed against SDL failed to recognise the classical digestive lipases. Altogether, these results suggest that SDL is a member of a new group of digestive lipases belonging to invertebrates.

Mesobuthus gibbosus (Scorpiones: Buthidae) on the island of Rhodes -- hybridization between Ulysses' stowaways and native scorpions?

Allozyme data suggest that the Rhodes population of Mesobuthus gibbosus is a hybrid population of recent origin. Namely, it is a mixture between an autochthonous population and an artificially introduced population probably from the Greek mainland. All samples were mainly composed of F1 hybrid genotypes and genotypes either fixed for autochthonous or introduced alleles. Back-cross hybrid genotypes were very rare. Mitochondrial DNA analysis, in contrast, revealed only one group of closely related haplotypes that are unique for the Rhodes populations, thus suggesting asymmetric introgression of the two marker classes.

Purification of a unique glycoprotein that enhances phenol oxidase activity in scorpion (Heterometrus bengalensis) haemolymph

A monomeric glycoprotein (SGP) of Mr 32,000 was isolated to purity from scorpion (Heterometrus bengalensis) haemolymph by (NH4)2SO4 fractionation, chromatofocusing and h.p.l.c. The homogeneity of SGP is confirmed by polyacrylamide-gel electrophoresis. SGP is soluble in 100%-satd. (NH4)2SO4 solution. Needle-shaped crystals of SGP were obtained in an aqueous environment. The glycan part of the molecule contains arabinose, which does not commonly occur in animal glycoproteins. Amino acid analysis demonstrated a preponderance of glycine, tyrosine and glutamic acid. SGP enhances phenol oxidase (EC 1.14.18.1) activity.

On the possible mode of action of neurohormones on cholinesterase activity in the ventral nerve cord of scorpion, Heterometrus fulvipes

It is shown that Km of ChE is not affected by the neurohormones but Vmax is increased and decreased in presence of acceleratory and inhibitory neurohormones respectively. Hence it is suggested that the neurohormones might modulate the enzyme activity be altering the maximal velocities (Vmax) rather than affecting the enzyme affinity (Km) towards the substrate.