Purification of thymocyte growth peptide (TGP) from sheep thymus. Relationship to FTS/thymulin

Thymocyte growth peptide (TGP) initiates DNA synthesis in immature thymocytes and has previously been characterized as an acidic peptide isolated from calf thymus. We now report the isolation of TGP from sheep thymus and show it to be a nonapeptide with a large N-terminal blocking moiety characterized by high UV absorbance. The amino acid composition is identical to FTS, consisting of 2 Gly, 2 Ser, 2 Glx, 1 Ala, 1 Lys, 1 Asx. In contrast to FTS, TGP is acidic with an apparent isoelectric point of 4.2 and a high UV absorbance at 270–280 nm. Reverse phase chromatography of TGP at an acidic pH results in a change of the molecule and the appearance of two new compounds TGP-A and TGP-B, both with less than 50% of the original TGP activity. Full activity could be restored by the addition of ZnCl2 to TGP-A. Both TGP-A and B have some amino acid composition and high UV absorbance as native TGP. We propose that TGP consists of a non-peptide moiety bound to the N-terminal of the nonapeptide Glu-Ala-Lys-Ser-Gln-Gly-Gly-Ser-Asn and that the active molecule is stabilized by Zn2+.

High Density Tissue Culture on Microporous Membranes Perfused by Blood: Report of a New Bioartificial System

A new tissue culture system has been developed to sup-port high density cell growth using the sheep as the host. Cellular nutrition is provided by plasma solutes as they diffuse from arterial blood across microporous polycarbonate membranes into a device attached to an arteriovenous shunt. Culture chambers are constructed with transparent polycarbonate to allow photomicroscopy of the tissue in situ. System performance is demonstrated by the high density growth of fetal sheep thymus allografts and rat soft tissue sarcoma xenografts.

Comparative study of the glycosphingolipids of chicken bursa of Fabricius and of chicken, rat and human thymus

1. The glycosphingolipid compositions of the thymus and bursa of Fabricius of young male chickens were compared. The two tissues were found to contain complex mixtures of both neutral glycosphingolipids and gangliosides. Both tissues contained mono-, di-, tri-, tetra- and penta-glycosylceramides; the pentaglycosylceramide displayed a reaction of identity with authentic Forssman antigen when tested against a specific anti-(Forssman antigen) serum. The ganglioside G(m3) containing N-acetylneuraminic acid was the principle ganglioside of both tissues. 2. The thymus contained appreciable amounts of the simple ganglioside N-acetylneuraminylgalactosylceramide, a compound not found in the bursa. The ganglioside G(d3) (disialohaematoside) was detected in both tissues. 3. Rat and human thymus, like sheep thymus (Narasimhan, Hay, Greaves & Murray (1976) Biochim, Biophys. Acta 431, 578-591), both contained a tetraglycosylceramide species as their most complex neutral glycosphingolipid and possessed little or no Forssman antigen. They also contained a complex mixture of gangliosides. 4. The possible significance of these results is briefly discussed.