The influence of genetic and environmental factors on the metabolism of a single oral dose of ethanol 1.2 ml per kg body weight was analysed in 19 identical and 21 fraternal healthy, adult, un-selected male twin pairs. The heritability values of the rates of absorption, degradation and elimination of ethanol were 0.57, 0.41 and 0.46 respectively. Environmental factors, such as daily alcohol intake and smoking, increased the rate of elimination of blood alcohol. Intrasubject variation in ethanol metabolism was studied by repeated tests in 11 male volunteers at intervals of at least 2 months, under the same conditions as in the twins; the coefficients of variation for parameters of metabolism was about 8%. The results demonstrate both genetic control of ethanol absorption, degradation and elimination and the appreciable influence of environmental factors. The almost total genetic control of ethanol metabolism postulated by Vesell et al. (1971) could not be confirmed.
Nuclear DNA binding protein p92 is a sequence specific octamer binding protein with identical molecular weight as the ubiquitous octamer binding protein Oct-1. It binds to octamer related sequences from the enhancer of human papillomavirus type 18. The activity and intracellular distribution of p92 is regulated by extracellular signals. In serum starved Hela-fibroblast hybrid cells p92 is localized to the cytosol. Serum stimulation leads to nuclear import of p92. In fractions of asynchronously growing cells, which were separated according to cell cycle phases into G1, S, and G2 populations by centrifugal elutriation, p92 DNA binding is confined to S phase. In binding site blots however, p92 DNA binding activity is also present in G1 and G2. In G1 and G2 DNA binding activity of p92 is masked by a novel nuclear inhibitor I-92. The cyclic association of p92 with its inhibitor I-92 provides a new mechanism of regulating S phase dependent activity of a sequence specific DNA binding protein.
Biochemical and autoradiographic evidence show both glycogen synthesis and the presence of glycogen synthase (UDP glucose [UDPG] : glycogen 4-a-D-glucosyltransf erase; EC 2.4 .1 .11) in isolated nuclei of Ehrlich-Lettre mouse ascites tumor cells of the mutant subline H D33. 5 d after tumor transplantation, glycogen (average 5-7 pg/cell) is stored mainly in the cell nuclei . The activity of glycogen synthase in isolated nuclei is 14 .5 mU/mg protein. At least half of the total cellular glycogen synthase activity is present in the nuclei . The nuclear glycogen synthase activity exists almost exclusively in its b form . The K,, value for (a + b) glycogen synthase is 1 x 10-3 M UDPG, the activation constant is 5 x 10 -3 M glucose-6-phosphate (Glc-6-P) .Light and electron microscopic autoradiographs of isolated nuclei incubated with UDP-[1-3 H]glucose show the highest activity of glycogen synthesis not only in the periphery of glycogen deposits but also in interchromatin regions unrelated to detectable glycogen particles. Together with earlier findings on nuclear glycogen synthesis in intact HD33 ascites tumor cells (Zimmermann, H .-P., V. Granzow, and C. Granzow. 1976 . J. Ultrastruct. Res. 54 :115-123), the results of tests on isolated nuclei suggest a predominantly appositional mode of nuclear glycogen deposition, without participation of the nuclear membrane system .In intact cells, synthesis of UDPG for nuclear glycogen synthesis depends on the activity of the exclusively cytoplasmic UDPG pyrophosphorylase (UTP : a-D-glucose-1-phosphate uridylyltransferase ; EC 2.7 .7 .9) . However, we conclude that glycogen synthesis is not exclusively a cytoplasmic function and that the mammalian cell nucleus is capable of synthesizing glycogen .Intranuclear glycogen deposition has been observed in amphibian (19), avian (11), and a variety of mammalia cells, particularly in hepatocytes (5,28,30,38), cells of renal collecting tubules (6), and cardiac muscle cells (8), partly under normal, partly under various pathological conditions . With respect to the origin of intranuclear glycogen, translocations of cytoplasmic glycogen particles into the nuclear compartment (30,40) free wild-type Ehrlich-Lettrt; ascites tumor, which was manipulated pharmacologically by means of N-methyl-colchicamide (27). A genome mutation of HD33 cells is associated with various phenotypical deviations from the wild type,' among which a pronounced nuclear and/or cytoplasmic glycogen storage is the most conspicuous (46). Characteristically, between days 4 and 6 after transplantation, glycogen deposits of increasing size are located chiefly within the tumor cell nuclei . Additional cytoplasmic glycogen storage is restricted to later stages oftumor development (46). On days 5 and 6, pronounced nuclear glycogen storage coincides with minimal cytoplasmic glycogen deposition in interphase cells . Thus, cells at this stage of tumor development provide a unique substrate for an analysis of their nuclear glycogen metabolism.In previous communications (...
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