Detection of pinocytic activity using selective staining with phosphotungstic acid

Summary Post-staining with phosphotungstic acid has been investigated using thin sections of isolated tomato fruit protoplast material. Certain areas of the plasmalemma and some cytoplasmic vesicles were found to stain intensely, and this selectivity of staining has been shown to be associated with pinocytic activity.This work was supported by a special grant from the S.R.C. One of us (MAM) acknowledges the award of an S.R.C. Research Studentship. This work is part of a thesis approved for the degree of Ph.D. in the University of Nottingham (MAM).     

Protein synthesis in tomato fruit locule tissue: The sites of synthesis and the pathway of carbon into protein

Summary The net increase in total protein during development of tomato fruit locule tissue has been further investigated with respect to the sites of protein synthesis within the cells. The results point to the plastids as being the major sites of protein synthesis. This is supported by radioisotope experiments in which labelled carbon from bicarbonate has been show to appear in protein at a higher rate than exogenously supplied amino acid. Isolated plastids incorporate carbon from bicarbonate, glucose and pyruvate into protein, and it is suggested that the pathway of carbon into protein involves photosynthetic pathways. The results are discussed with reference to possible differences between protein synthesis in plastids, and protein synthesis in the cytoplasm of plant cells.     

The nodulation of micro-propagated plants of Parasponia andersonii by tropical legume rhizobia

A simple clonal micro-propagation system for Parasponia andersoniiwas employed to study the nodulation response of this non-legumeto inoculation by the broad host range Rhizobium sp. NGR234,isolated from Lablab purpureus, and also to tropical legumerhizobia isolated from Aeschynomene species. Partially effectivenodules, assayed by acetylene reduction and ¹⁵N dilution procedures,were induced with strain NGR234 and its spontaneous streptomycinresistantmutant ANU240. Effective nodules were produced by one of theAeschynomene strains (ORS302) tested, with rates of acetylenereduction comparable to those of root nodules produced by Bradyrhizobiumstrain CP279, originally isolated from P. andersonii. Lightand transmission electron microscopy showed that there was acorrelation between the nitrogen fixing capability of the symbiosisbetween NGR234 and Parasponia and the number of persistent infection(fixation) threads within the nodule cells. Key words: Parasponia, Bradyrhizobium, Rhizobium, Aeschynomene, micro-propagation, root nodules, nitrogen fixation     

Prolific plant regeneration from protoplast-derived tissues of Lotus corniculatus L. (birdsfoot trefoil)

Protoplasts isolated enzymatically from seedling roots, hypocotyls and cotyledons of Lotus corniculatus L. produced callus which underwent prolific shoot regeneration. The rapidity and ease of recovering plants from protoplast-derived tissues makes this forage legume an attractive experimental system for genetic manipulation.