BackgoundThe venom of the Cuban scorpion Rhopalurus junceus is poorly study from the point of view of their components at molecular level and the functions associated. The purpose of this article was to conduct a proteomic analysis of venom components from scorpions collected in different geographical areas of the country.ResultsVenom from the blue scorpion, as it is called, was collected separately from specimens of five distinct Cuban towns (Moa, La Poa, Limonar, El Chote and Farallones) of the Nipe-Sagua-Baracoa mountain massif and fractionated by high performance liquid chromatography (HPLC); the molecular masses of each fraction were ascertained by mass spectrometry analysis. At least 153 different molecular mass components were identified among the five samples analyzed. Molecular masses varied from 466 to 19755 Da. Scorpion HPLC profiles differed among these different geographical locations and the predominant molecular masses of their components. The most evident differences are in the relative concentration of the venom components. The most abundant components presented molecular weights around 4 kDa, known to be K+-channel specific peptides, and 7 kDa, known to be Na+-channel specific peptides, but with small molecular weight differences. Approximately 30 peptides found in venom samples from the different geographical areas are identical, supporting the idea that they all probably belong to the same species, with some interpopulational variations. Differences were also found in the presence of phospholipase, found in venoms from the Poa area (molecular weights on the order of 14 to 19 kDa). The only ubiquitous enzyme identified in the venoms from all five localities studied (hyaluronidase) presented the same 45 kD molecular mass, identified by gel electrophoresis analysis.ConclusionsThe venom of these scorpions from different geographical areas seem to be similar, and are rich in peptides that have of the same molecular masses of the peptides purified from other scorpions that affect ion-channel functions.

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Context: In Cuba, the venom of the endemic scorpion Rhopalurus junceus has been used in traditional medicine for cancer treatment. The genetic variability in populations from distinct origin and differences in the composition of venom –a little explored topic- could influence the pharmacological effects of products used in medical practice. Aims: To characterize the populations of R. junceus from six different districts of the Moanicum sector in northeastern Cuba, taking into account the variations in the sequences of cytochrome oxidase subunit I gene (COI) and peptide masses of venom. Methods: For the genetic characterization, a 658 bp gene fragment of COI was amplified by PCR. The genetic structure of populations was analyzed hierarchically, using an analysis of molecular variance (AMOVA). In proteomic analysis, molecular masses of venom constituents were arranged in increasing order, and different components were considered when masses differed by 2 Da. Results: R. junceus species in the six districts studied in the Moanicum sector belong to different populations. The sequences of COI gene showed high levels of genetic variability, recovering 47 haplotypes (87% unique). The composition of the venom was also significantly different between the districts. The most abundant components presented masses of 3-6 kDa (K+-channel specific peptides) and 6,1-10 kDa (Na+-channel specific peptides). Conclusions: Populations of R. junceus showed high genetic differentiation and a broad intraspecific variation in the venom peptides (3-10 kDa) in six districts of Moanicum sector of Cuba. This richness in scorpion varieties with different toxins profile should be considered for pharmacological applications.