Some chemical properties of isolated pea nucleoli.

Isolated nuclei and nucleoli of ungerminated pea embryos have been analyzed chemically for their content of DNA, RNA, zinc, iron, phosphorus, and protein sulfhydryl groups. The values obtained cannot be considered to represent the whole of the living nucleolar body as an undetermined amount of material is extracted from nucleoli in the course of their isolation. Only negligible amounts of DNA have been found in the isolated nucleoli; most of the DNA released on disruption of nuclei appears in a fraction showing very few structures under the light microscope.

The isolation of nucleoli from ungerminated pea embryos.

A method is described for the isolation of nuclei and nucleoli from ungerminated pea embryos. Electron micrographs of the nucleolar preparation indicate a high degree of purity but only a partial preservation of composition, because of a loss of material from the nucleoli which occurs during the isolation procedure.

The accumulation of soluble deoxyribosidic compounds in relation to nuclear division in anthers of Lilium longiflorum.

Intervals of sporogenous DNA synthesis in lily anthers are associated with marked accumulations of methanol- and acid-soluble deoxyribosidic compounds. There are differences in solubility between compounds accumulating at meiosis and those accumulating at mitosis. The formation of these compounds appears to be related to a breakdown of somatic DNA.

Variations in sulfhydryl concentration during microsporocyte meiosis in the anthers of Lilium and Trillium.

Anthers of lily and trillium were followed with respect to variations in protein and soluble sulfhydryls during meiosis and mitosis of the sporogenous tissue. In lily, the meiotic and mitotic cycles are each preceded by a rise in soluble -SH; in trillium there is only one rise which precedes meiosis. During division there is a marked drop in soluble -SH and a rise in soluble disulfides.

The position of the cell nucleus in pathways of hydrogen transfer: cytochrome C, flavoproteins, glutathione, and ascorbic acid.

A study has been made of calf thymus and liver tissue to ascertain the position of the nucleus with respect to mechanisms capable of hydrogen transfer. Although previous work had shown that reduced pyridine nucleotide coenzymes are produced in the course of nuclear metabolism, it has now been established that the flavoprotein system of cytochrome c reductase, cytochrome c, and most, if not all, of other flavoproteins are absent from nuclei. Metabolites capable of cytochrome c reduction, notably ascorbic acid and glutathione, have been demonstrated in the nuclei.