Peptide transport by embryos of germinating barley (hordeum vulgare)

Two new fluorescent-labelling techniques for studying peptide transport are described. A peptide transport system has been demonstrated in a higher plant tissue, the scutellum of germinating barley embryos. This system has been extensively characterized, and found to have many similarities to peptide transport systems in microorganisms and mammalian tissues. Evidence has also been obtained for the existence of a peptide transport system in the membrane of an intracellular organelle, possibly the vacuole. Peptide transport is an active process and appears to require the production of a proton gradient across the plasmalemma. Disruption of the proton gradient not only inhibits peptide transport, but also causes general exodus of amino acids from the embryo and affects amino acid metabolism. Considerable pools of small peptides have been detected in both the endosperm and embryo of the germinating barley grain. The concentrations of peptides achieved in the endo sperm are of the right order of magnitude for the efficient operation of the peptide transport system. It seems that the uptake of small peptides by the scutellum of germinating barley embryos is of considerable importance in the transfer of nitrogen from the endosperm to the embryo during the iLobilization of zhe protein storage reserves

A SOCIAL COGNITIVE THEORY PERSPECTIVE ON INDIVIDUAL REACTIONS TO COMPUTING TECHNOLOGY

Understanding individual reactions to computing technology is a central concern of information systems research. This research seeks to understand these reactions from the perspective of Social Cognitive Theory (Bandura 1977, 1978, 1982, 1986), a widely accepted theory of behavior in Social Psychology and Industrial/Organizational Psychology. The theory holds that behavior, environment, and cognitive and other individual factors are engaged in an ongoing reciprocal interaction. Two cognitive factors in particular are given prominence in the theory: (1) outcome expectations, or beliefs about the consequences of behavior and (2) self-efficacy, beliefs about one\u27s ability to successfully execute particular behaviors. A model of individual reactions to computing technology based on this theory was tested on a sample of 940 Canadian knowledge workers. Eleven of the fourteen hypotheses were supported by the analysis. Key findings were that self-efficacy, outcome expectations, affect and anxiety all had a direct influence on computer use. In addition, outcome expectations and self-efficacy were found to indirectly influence computer use through affect and anxiety. Tile behavior and influence of others in the individuals\u27 reference groups was found to exert a small influence on selfefficacy and outcome expectations