Soluble scute proteins of healthy and ill desert tortoises (Gopherus agassizii)

Objectives-To characterize protein composition of shell scute of desert tor toises and to determine whether delectable differences could be used to ide ntify healthy tortoises from tortoises with certain illnesses. Animals-20 desert tortoises. Procedures-Complete postmortem examinations were performed on all tortoises , Plastron scute proteins were solubilized, scute proteins were separated b y use of sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAG E), and proteins were analyzed, using densitometry. Two-dimensional immobil ized pH gradient-PAGE (2D IPG-PAGE) and immunoblot analysis, using polyclon al antisera to chicken-feather beta keratin and to alligator-scale beta ker atin, were conducted on representative samples. The 14-kd proteins were ana lyzed for amino acid composition. Results-The SDS-PAGE and densitometry revealed 7 distinct bands, each with a mean relative protein concentration of > 1%, ranging from 8 to 47 kd, and a major protein component of approximately 14 kd that constituted up to 75 % of the scute protein. The 2D IPG-PAGE revealed additional distinct 62- an d 68-kd protein bands. On immunoblot analysis, the 14-, 32-, and 45-kd prot eins reacted with both antisera. The 14-kd proteins had an amino acid compo sition similar to that of chicken beta keratins. There was a substantial di fference in the percentage of the major 14-kd proteins from scute of ill to rtoises with normal appearing shells, compared with 14-kd proteins of healt hy tortoises. Conclusions and Clinical Relevance-The major protein components of shell sc ute of desert tortoises have amino acid composition and antigenic features of beta keratins. Scute protein composition may be altered in tortoises wit h certain systemic illnesses.