The Deciphered Genome of Mesobuthus martensii Uncovers the Resistance Mysteries of Scorpion to Its Own Venom and Toxins at the Ion Channel Level

Scorpions are amongst the most ancient arthropods, as the oldest fossils were dated from the late silurian (Proscorpius osborni, 418 million years B.P.) [1]. Extant scorpions (with about 2,000 species spreading globally) are therefore 'living fossils', which retained all of the primitive features except that they are considerably smaller compared to their up to 1-meter long Brontoscorpio anglicus ancestor (a species of fossil scorpion from Silurian to lower Devonian) [2]. From the fossils of the late Silurian period, scorpions were found to have developed and adapted their venomous systems [1]. Evolving over the past 400 million years, scorpion venoms contain a variety of compounds, including the more or less potent and selective peptide toxins acting on the diverse and ubiquitous ion channel proteins. The latter are widely distributed in many systems, such as nervous, skeletal and cardiovascular in the scorpion's prey (or predator). Basically, the severity of scorpion envenomation ranges from local pain and paresthesia to lethal cardiotoxicity and encephalopathy [3]. At present, it is a serious cause of mortality in several Latin countries, in South America, southern and western Asia, and Africa. The number of scorpion stings is estimated to be ca. 1.2 million per year worldwide, resulting in more than 3,200 deaths [4]. Scorpions are known for their deadly venoms but are likely resistant to their own venoms due to the 'sexual' stings and cannibalism occurring in many scorpion species. In 1998, it was reported that the scorpion Androctonus australis, as well as its muscle and nerve fibers, were insensitive to both its own venom and purified toxins [5]. Fifteen years later, the mysterious veil of scorpion resistance to its own venom and toxins was unmasked at the molecular level, by the deciphered draft genome sequence of the Chinese golden scorpion Mesobuthus martensii (eastern Asia) that has been recently published by the research group of Professor Wenxin Li [6]. The project started at Wuhan University back in the 1990s, when Professor Li and his colleagues continuously discovered scorpion toxin cDNAs after constructing the first venomous gland cDNA library of M. martensii [7]. They pursued in exploring scorpion toxin OPEN ACCESS