Molecular and functional identification of a short-type peptidoglycan recognition protein, PGRP-S, in the Chinese soft-shelled turtle Pelodiscus sinensis

Peptidoglycan recognition proteins (PGRPs), which are discovered in invertebrates and vertebrates, play an important role in antibacterial immunity. However, the function of PGRPs is largely uninvestigated in reptiles. In the present study, a short-type PGRP gene, designed as C-turtle-PGRP-S, was identified in the Chinese soft-shelled turtle, Pelodiscus sinensis. The C-turtle-PGRP-S contains a highly conserved PGRP domain and has close relationship with PGRP-S orthologues in other species according to sequence and phylogenetic analyses. C-turtle-PGRP-S gene was constitutively expressed in all detected tissues and was induced by Edwardsiella tarda. Additionally, recombinant C-turtle-PGRP-S showed PGN binding activity and antibacterial function against E. tarda. Therefore, it is suggested that the function of PGRP-S is likely to be conserved in reptile vertebrates, as observed in other vertebrates, shedding light on the evolutionary conservation of PGRPs.

Comparative Studies of Structural and Functional Properties of Snake Venom Metalloproteinases

Snake venom metalloproteinases (SVMPs) induces local and systemic effects on patients suffering from snakebite, degrading extracellular matrix (ECM) proteins such as collagen, gelatin, elastin, laminin, fibronectin, nidogen (entactin), and thrombospondin that cause local hemorrhage and tissue damage. They cleave or activate coagulation factors such as fibrinogen, fibrin, prothrombin, factor V, factor IX, factor X and protein C that bring about systemic coagulopathy. SVMPs and their truncated forms cleave or interfere with platelet adhesive proteins such as vWF, fibrinogen and collagen, and cleave or interfere with platelet receptors such as GPVI, alpha2beta1, GPIb, GPIX, and GPIIbIIIa that result in platelet aggregation defect. SVMPs induce cancer cell line to form morphological changes and apoptosis in vitro concordant with skin necrosis after snakebite in some cases. These local effects caused by SVMPs have no certain treatments, even with commercial anti-venom. SVMPs researches are focusing on their inhibitors, measurement and replacement of blood coagulation factor defects, or anti-cancer drug.

Characterization of the structure and composition of gecko adhesive setae

The ability of certain reptiles to adhere to vertical (and hang from horizontal) surfaces has been attributed to the presence of specialized adhesive setae on their feet. Structural and compositional studies of such adhesive setae will contribute significantly towards the design of biomimetic fibrillar adhesive materials. The results of electron microscopy analyses of the structure of such setae are presented, indicating their formation from aggregates of proteinaceous fibrils held together by a matrix and potentially surrounded by a limiting proteinaceous sheath. Microbeam X-ray diffraction analysis has shown conclusively that the only ordered protein constituent in these structures exhibits a diffraction pattern characteristic of beta-keratin. Raman microscopy of individual setae, however, clearly shows the presence of additional protein constituents, some of which may be identified as alpha-keratins. Electrophoretic analysis of solubilized setal proteins supports these conclusions, indicating the presence of a group of low-molecular-weight beta-keratins (14-20 kDa), together with alpha-keratins, and this interpretation is supported by immunological analyses.