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  • Author or Editor: Bruce L. Homer x
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Objectives—To characterize protein composition of shell scute of desert tortoises and to determine whether detectable differences could be used to identify 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 by use of sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and proteins were analyzed, using densitometry. Two-dimensional immobilized pH gradient-PAGE (2D IPG-PAGE) and immunoblot analysis, using polyclonal antisera to chicken-feather β keratin and to alligator-scale β keratin, were conducted on representative samples. The 14-kd proteins were analyzed 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- and 68- kd protein bands. On immunoblot analysis, the 14-, 32-, and 45-kd proteins reacted with both antisera. The 14-kd proteins had an amino acid composition similar to that of chicken β keratins. There was a substantial difference in the percentage of the major 14- kd proteins from scute of ill tortoises with normal appearing shells, compared with 14-kd proteins of healthy tortoises.

Conclusions and Clinical Relevance—The major protein components of shell scute of desert tortoises have amino acid composition and antigenic features of β keratins. Scute protein composition may be altered in tortoises with certain systemic illnesses. ( Am J Vet Res 2001;62:104–110)

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in American Journal of Veterinary Research



To determine optimal site for collection of bone marrow from desert tortoises, and to characterize cytologic staining and morphologic features of bone marrow hematopoietic cells.


16 desert tortoises.


Bone marrow was obtained at necropsy from the pelvis, proximal portion of the humerus, femur, and thickened portions of the cranial to craniolateral and caudal to caudolateral margins of the carapace and plastron for histologic and cytologic examinations. Cytocentrifuged preparations of marrow cells were evaluated for reactivity to cytochemical stains.


Histologic sections were adequate for evaluating acidophils, acidophil precursors, and erythrocyte precursors. It was difficult to differentiate among monocytes, lymphocytes, thrombocytes, and blast cells, and eosinophils could not be differentiated from heterophils. Basophils were in rare, small clusters of 3 to 12 cells. A few lymphoid follicles were found in the pelvis and long bones.

Use of cytochemical staining accomplished differentiation between agranular heterophil precursors and granulated heterophils, and between granulated eosinophils and basophils. Monocytes, azurophils, and monoblasts had similar staining features. Staining of erythrocyte precursors with Sudan black B differentiated them from lymphocytes. Only a few small cells with periodic acid-Schiff-positive cytoplasm were identified as thrombocytes. Lymphocytes did not stain with any of the cytochemical stains.


For histologic and cytologic evaluation of bone marrow hematopoietic cells, pelvis, proximal portion of the humerus, femur, and thickened portions of the peripheral cranial and caudal regions of the carapace and plastron are suitable sites to collect specimens. There are distinct cytochemical markers for heterophil, monocyte, and erythrocyte precursors, as well as later stage heterophils, eosinophils, basophils, monocytes, and azurophils. (Am J Vet Res 1996;57:1608–1615)

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in American Journal of Veterinary Research