Detection of the Nicotiana rustica chloroplast genome coding for the large subunit of Fraction I protein in a somatic hybrid in which only the N. tabacum chloroplast genome appeared to have been expressed

Nine plants were produced from anthers of a somatic hybrid which had been obtained by fusion of Nicotiana tabacum L. and N. rustica L. protoplants. As determined by electrofocusing, the Fraction I protein of the original somatic hybrid had largesubunit polypeptides exclusively of the N. tabacum type. Two of the plants regenerated from anthers contained Fraction-I-protein large subunits exclusively of the N. rustica type. Since each plant was regenerated from a single cell, the somatic hybrid must have had cells containing both the N. tabacum and N. rustica chloroplast genome although the latter was not expressed. Possibilities to account for this non-expression of a chloroplast genome in the somatic hybrid are discussed.     

Enhancement of the mutagenicities of N-methyl-N′-nitro-N-nitrosoguanidine and N-methyl-N-nitrosourea by glucose

The mutagenicity of N-methyl-N′-nitro-N-nitrosoguanidine to Salmonella typhimurium hisG46 was enhanced by pre-incubating the chemical with bacteria in sodium phosphate buffer. Addition of glucose (to 15 mM) to the pre-incubation mixture further enhanced the mutagenicity. Pre-incubation with glucose also increased the mutagenicity of N-methyl-N-nitrosourea. Fructose, galactose, pyruvate and succinate also enhanced the mutagenicity of N-methyl-N′-nitro-N-nitrosoguanidine. The effect of glucose was observed with S. typhimurium strains hisG46, TA1975, TA1950, TA1535 and TA100.     

Biosynthesis and excretion of hydrolases in germinating cereal seeds

The initial formation site of hydrolases in germinating cerealseeds and their subsequent release were examined using the substrate-filmtechnique. Early in the germination of cereal seeds, e.g., barley,wheat, rye, oat and maize, -amylase invariably appeared in theregion of the epithelial cells of the scutellum, whereas itlater gradually diffused into the entire region of the endospermtissues. The initial formation site of proteinase and RNA-asein germinating barley seeds was also confirmed to be in theepithelium. We conclude that the epithelium has a more importantrole in the enzymic breakdown of reserve substances stored inthe endosperm tissues than the aleurone layer. (Received October 19, 1979; )     

Streptococcal preparation OK-432 augments cytotoxic activity against an erythroleukemic cell line in humans

Summary The effects of OK-432, an inactivated and lyophilized preparation of a low-virulence strain of Streptococcus pyogenes, were evaluated on the cytotoxicity of lymphoid cells against a natural killer (NK)-sensitive erythroleukemic cell line K562 in patients with malignant diseases. When ten patients were treated postoperatively with daily injections of OK-432, a significant degree of augmentation in the cytotoxicity of peripheral blood lymphoid cells was evoked in all the patients, and the maximum level of cytotoxicity was on the third day after the beginning of the treatment. In spite of the successive daily administration, the level of cytotoxicity declined thereafter, but stayed higher than the pretreatment level. When OK-432 was injected IP in three patients with carcinomatous peritonitis, the cytotoxic activity of ascitic lymphoid cells was significantly enhanced. Cytotoxicity of in vitro-cultured lymphoid cells taken from peripheral blood of normal donors was also augmented by the addition of OK-432.     

Ecological and mathematical considerations on self-thinning in even-aged pure stands

It is emphasized in growth analysis of self-thinning populations that relative mortality rate pertains to the difference between relative growth rates and net assimilation rates, each of which are definable on a mean plant size basis or on a biomass basis. The time trends of the ratio of relative mortality rate to relative growth rates to be expected according to Tadaki's, Shinozaki's and Hozumi's models are compared with that of the eastern white pine population, and a good agreement is exhibited. As an alternative to Hozumi's model, a new model is constructed to unite the logistic theory of plant growth and the 3/2 power law concerning self-thinning, which so far have usually been applied independently to growth analysis. To construct the model the following assumptions are made: the fundamental equation to relate mean plant weight with density in self-thinning population proposed by Shinozaki, and a special population with a specific initial density which follows thew-p trajectory of the 3/2 power law type and has an exponential decrease in its density with biological time. Properties of the model are examined from ecological and mathematical viewpoints.     

Photoreaction of tyrosin-iodinated bacteriorhodopsin at low temperature

To elucidate the role of tyrosine residues in the shift of max and the light-driven proton pump of bacteriorhodopsin~ the photochemical reaction of tyrosine-iodinated bacteriorhodopsin (tyr-mod-bR) was investigated by low-temperature spectrophotometry. After 4–5 of 11 tyrosine residues of bacteriorhodopsin were iodinated, the meta-intermediate of tyr-mod-bR in 75% glycerol solution became so stable that its decay could be observed even at room temperature and i t was stable in the dark for several hours at –65°C.Four batho-intermediates were formed by irradiation with green light (500 nm) at –170°C. Like native bacteriorhodopsin, these batho-intermediates were photoreversible at –170°C. Four corresponding meta-intermediates were also formed by irradiation at –60°C. Using the difference spectra between meta-intermediates and tyr-mod-bR, the absorption spectra of four kinds of tyr-mod-bRs, batho-intermediates, and meta-intermediates were estimated. Each was at shorter wavelengths than that of its corresponding type in native bacteriorhodopsin. The results indicate that two or more tyrosine residues have some role in determining color in native bacteriorhodopsin.     

A contractile ring and cortical changes found in the dividing Tetrahymena pyriformis

A contractile ring consisting mainly of microfilaments was found in the fission zone of dividing Tetrahymena pyriformis. Diameters of the microfilaments were widely distributed from 2.5 to 15 nm. Ring-associated structures such as lateral stripes, linkers and beads with siender tails were recognized. Lateral stripes arranged at regular intervals of about 84 nm on some parts of microfilament bundles were found in both tangential and transverse sections, suggesting that they correspond to bands fastening the contractile ring microfilaments. Linkers that connect individual lateral stripes to the epiplasmic layer were present. Beads or beads with slender tails were found to be arranged on some microfilaments.The results of the present paper also indicate that drastic morphological changes occur in the cortex of the fission zone, especially in the epiplasmic layer, accompanying contraction of the division furrow. The epiplasmic layer which was proved to be a compact filamentous network in this study has been known to exist at the periphery of cytoplasm in immediate contact with one of the cell surface membranes, the inner alveolar membrane; however, in the fission zone of the dividing ceil, it was frequently separated from the membrane and subsided into the cytoplasm. The subsided epiplasmic layer was then loosened and dispersed. The subsidence of the epipiasmic layer appears to be caused by the force generated by the contraction of the contractile ring and transmitted with the linkers to the epiplasmic layer. The changes observed in the epiplasmic layer are presumably indispensable for the rigid cortical layer contraction involved in cytokinesis of Tetrahymena.