Implantation of cultured thymic fragments in congenitally athymic nude rats: ignorance of thymic epithelial haplotype in generation of alloreactivity.

We studied the development of thymus-dependent immunity in congenitally athymic nude rats after implantation of cultured thymic fragments (CTF), particularly the development of in vitro alloreactivity in allogeneic combinations. CTF of DA (RT1a), PVG (RT1c), and RP (RT1p(u,1] origin were implanted in nude rats of WAG (RT1u) origin. In analysis 14 to 18 wk later, all recipients exhibited thymus-dependent immunocompetence assessed by (immuno)-histology of lymphoid organs and responsiveness to in vitro concanavalin A stimulation and in vivo ovalbumin immunization.

Identification of Abscisic Acid in Tulipa gesneriana L. by Gas-Liquid Chromatography with Electron Capture and Combined Gas-Liquid Chromatography and Mass Spectrometry.

A major growth inhibitory substance of tulip bulbs (Tulipa gesneriana L. cv Paul Richter) has been unequivocally shown to be abscisic acid (ABA). The ABA methyl ester of the free ether-soluble acid fractions of tulip organs had the identical retention time on gas-liquid chromatography with electron capture detector as authentic ABA methyl ester.

Terpene Biosynthesis in Cell-free Extracts and Excised Shoots from Wedgwood Iris.

Excised shoots and cell-free extracts prepared from Wedgwood iris (Iris hollandica Hoog. "Wedgwood") shoots metabolized (14)C-labeled mevalonic acid (MVA). By using cell-free extracts, the (14)C from MVA-1-(14)C was recovered as (14)CO(2), while that from MVA-2-(14)C was recovered as neutral terpenes, acid-hydrolyzable terpenes, or (14)CO(2).

Temperature Regulation of Endogenous Gibberellin Activity and Development of Tulipa gesneriana L.

The changes in the contents of free and bound gibberellin-like activity (GA) of Tulipa gesneriana L. cv. Ralph during development under 2 temperature conditions were studied.