Comparative investigations of the sandfish's -keratin (Reptilia: Scincidae: Scincus scincus)

The sandfish (Scincidae: Scincus scincus) is a lizard capable of moving through desert sand in a swimming-like fashion. The epidermis of this lizard shows a high resistance against abrasion together with a low friction to sand as an adaption to a subterranean life below the desert's surface, outperforming even steel. The low friction is mainly caused by chemical composition of the scales, which consist of glycosylated -keratins. In this study, the friction, the micro-structure, the glycosylation of the -keratin proteins and -keratin coding DNA of the sandfish in comparison to other reptilian species was investigated, mainly with the closely related Berber skink (Scincidae: Eumeces schneideri) and another sand swimming species, the not closer related Shovel-snouted lizard (Lacertidae: Meroles anchietae). Glycosylated -keratins of the sandfish, visualized with different lectins resulted in O-linked glycans through PNA employed as carbohydrate marker. Furthermore, the glyc osylation of -keratins in various squamatean species was investigated and all species tested were found positive; however, it seems like both sand swimming species examined have a much stronger glycosylation of their -keratins. In order to prove this finding through a genetic foundation, DNA of a -keratin coding gene of the sandfish was sequenced and compared with a homologue gene of Eumeces schneideri. By comparison of the protein sequence, a higher abundance of O-glycosylation sites was found in the sandfish (enabled through the amino acids serine and threonine), giving molecular support for a higher glycosylation of the -keratins in this species.