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A satisfactory synthesis of crystalline betaine aldehyde was achieved and methods were developed for the isolation and characterization of choline, betaine aldehyde, betaine and related compounds. The suitability of these methods (ion-exchange column chromatography and thin-layer chromatography in particular) were demonstrated by their application to the choline oxidase system known to exist in the mitochondria of rat liver. Attempts were made to demonstrate a similar choline oxidase system in plants. Experiments designed to demonstrate the existence of these enzymes by spectrophotometric and polarographic methods in mitochondria extracted from plant sources were largely unsuccessful. The mitochondria were structurally intact and were of high bio chemical integrity. On the isolated occasions when stimulation of respiration occurred when choline was supplied as substrate, the formation of betaine aldehyde or betaine was never confirmed by the characterization techniques which had been developed. The existence of a permeability barrier to the uptake of choline was discounted as an explanation of the 'latency' of the enzymes investigated. The methods employed to overcome such a barrier in mitochondria extracted from rat liver were without effect on the plant systems. Radioactive choline was taken up by mitochondria, from plants and a fraction of the labelled compound became closely associated with the mitochondrial membranes. However, the level of radioactivity did not increase with time indicating an upper limit of choline uptake or a continual utilization of the choline taken up. The existence of an alternative pathway for the oxidation of choline was superficially examined but no definite conclusions could be reached.

Two developmental systems for leaves of Festuca pratensis were compared, namely development along the leaf (base to apex) and development of the whole leaf with time. The methods for examination of nucleic acids from leaves of F. pratensis were optimised and the changes occurring in rRNA fractions, tRNAs and polyribosomes during both developmental systems were recorded. These changes were related to changes in levels and syntheses of soluble and particulate proteins. Activities of enzymes intimately involved in these relationships, namely RNAses, ATPases, phosphatases, pyrophosphatases and phosphodiesterases were monitored during development. The metabolic status was further examined by the study of the polypeptide - synthesizing capacity of the ribosomes at different stages as revealed in wheatgerm- derived cell-free systems. Three phases of increased metabolism were apparent in both developmental systems but only the initial and final phases involved increased RNA synthesis which was correlated with increased protein synthetic capacity. Work involving "greening-up" and excision showed some similarities to the normal courses of development but also important differences particularly with respect to the magnitude of the response.

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