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Not as docile as it looks? Loxosceles venom variation and loxoscelism in the Mediterranean Basin and the Canary Islands - PubMed

Not as docile as it looks? Loxosceles venom variation and loxoscelism in the Mediterranean Basin and the Canary Islands

Enric Planas et al. Toxicon. 2015 Jan.

Abstract

The medical importance of Loxosceles spiders has promoted extensive research on different aspects of their venoms. Most of the reported cases of loxoscelism have occurred in the Americas, and thus, much work has focused on North and South American Loxosceles species. Interestingly, loxoscelism cases are rare in the Mediterranean Basin although Loxosceles rufescens, endemic to the Mediterranean, is an abundant spider even in human-altered areas. Thus, it has been suggested that the venom of L. rufescens could be of less medical relevance than that of its congeners. In this study, we challenge this hypothesis by using multiple approaches to study venom variation in selected species and lineages from the Mediterranean Basin and the Canary Islands. We found that SMase D activity, the key bioactive component of Loxosceles venom, is comparable to American species that are confirmed to have medically relevant bites. The venom protein composition using SDS-PAGE presents some differences among regional Loxosceles taxa in banding pattern and intensity, mostly between the Canarian and L. rufescens lineages. Differences between these species also exist in the expression of different paralogs of the SicTox gene family, with the Canarian species being less diverse. In conclusion, our results do not support the challenged hypothesis, and suggest that venom of these species may indeed be as potent as other Loxosceles species. Pending confirmation of loxoscelism with direct evidence of Loxosceles bites with species identification by professionals, Loxosceles in the Mediterranean region should conservatively be considered medically relevant taxa.

Keywords: Evolution; SDS-PAGE; SicTox; Sphingomyelinase D (SMase D); Spider.

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Conflict of interest statement

Conflict of interest

The authors declare that there are no conflicts of interest.

Figures

Figure 1_
Figure 1_

SDS-PAGE comparison of crude venoms from three lineages (A6, B2 and B5) of Loxosceles rufescens and two Loxosceles from the Canary Islands (GC and GM). Main banding clusters are labeled (A–D) for reference in the text. Schematic tree representing the phylogenetic relationship between L. rufescens lineages (A6, B2 and B5) and Canarian species. Broad range molecular weight markers are labeled for size reference.

Figure 2 _
Figure 2 _

SMase D-specific activity of 0.5 mg of total protein from crude venom from each Loxosceles rufescens lineage (A6, B2 and B3) and from the two Canary Islands Loxosceles species (LG and GC). We used L. arizonica for positive control and substituted 1 x Amplex Red Buffer for venom in blank.

Figure 3 _
Figure 3 _

Phylogenetic tree obtained from Bayesian inference analysis of the combined dataset of SMase D sequences that were minimally 5% different in amino acid sequence divergence for each species or lineage (colored accordingly) obtained in this study and those from Binford et al. (2009) that follow the same criteria. Black dots in nodes indicate posterior probability support > 0.95.

Figure 4 _
Figure 4 _

Relative proportions of SMase D paralogs expressed in each Loxosceles rufescens lineage (A6, B2 and B3) and from the two Canary Islands Loxosceles species (LG and GC). n = number of sequences.

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References

    1. Abdel-Rahman MA, Omran MAA, Abdel-Nabi IM, Ueda H, McVean A, 2009. Intraspecific variation in the Egyptian scorpion Scorpio maurus palmatus venom collected from different biotopes. Toxicon 53, 349–359. - PubMed
    1. Barbaro KC, Knysak I, Martins R, Hogan C, Winkel K, 2005. Enzymatic characterization, antigenic cross-reactivity and neutralization of dermonecrotic activity of five Loxosceles spider venoms of medical importance in the Americas. Toxicon 45, 489–499. - PubMed
    1. Binford GJ, 2001. Differences in venom composition between orb- weaving and wandering Hawaiian Tetragnatha (Araneae). Biol. J. Linn. Soc 74, 581–595.
    1. Binford GJ, Bodner MR, Cordes MHJ, Baldwin KL, Rynerson MR, Burns SN, Zobel-Thropp PA, 2009. Molecular evolution, functional variation, and proposed nomenclature of the gene family that includes sphingomyelinase D in sicariid spider venoms. Mol. Biol. Evol 26, 547–566. - PMC - PubMed
    1. Binford GJ, Wells MA, 2003. The phylogenetic distribution of sphingomyelinase D activity in venoms of Haplogyne spiders. Comp. Biochem. Physiol. B 135, 25–33. - PubMed

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