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Biomedical subjects

R I Francki

Publications and source records attributed to R I Francki.

At least 73 records · Page 4Linked to original sources
PubMed1971

Metabolism of Separated Leaf Cells: II. Uptake and Incorporation of Protein and Ribonucleic Acid Precursors by Tobacco Cells.

Enzymatically separated tobacco leaf cells took up amino acids, uracil, and uridine from the incubation medium and incorporated them into proteins and RNA, respectively, at a linear rate for approximately 30 hours. Both uptake and incorporation were light-dependent, although cells prepared from preilluminated plants or preillumination of cells allowed some uptake and incorporation to occur in the dark. The light was necessary to satisfy a photosynthetic requirement, but could be replaced in part by ATP in the medium.Several lines of evidence support the conclusion that the rate of uptake of amino acids, uracil, and uridine was dependent upon the subsequent incorporation of these compounds into macromolecules.

Journal Article↗
PubMed1971

Metabolism of separated leaf cells: I. Preparation of photosynthetically active cells from tobacco.

Suspensions of mesophyll cells, prepared from tobacco leaves by treatment with pectinase, fixed CO(2) by photosynthesis. The products of carbon assimilation were similar for both cells and intact tissue. The cells sustained a constant fixation rate for 20 to 25 hours. For optimal CO(2) fixation, enzymatic maceration of the tissue was accomplished in 0.8 m sorbitol, but photosynthesis was optimal in 0.6 m sorbitol at pH 7 to 7.5. A hypertonic environment during maceration, which results in cell plasmolysis, is essential to maintain intact plasmalemmas and hence photosynthetically active cells. For sustained CO(2) fixation, light intensities below 500 foot-candles were required. Higher light intensities (to 1000 foot-candles) gave high initial rates of CO(2) fixation, but the cells bleached and were inactive on prolonged incubation. At pH 7.0 the bicarbonate concentration at maximal velocity of CO(2) fixation was about 1.5 mm and the apparent Km for bicarbonate was 0.2 mm.

Journal Article↗