Enzymatic amplification involving glycosyltransferases forms the basis for the increased size of asparagine-linked glycans at the surface of NIH 3T3 cells expressing the N-ras proto-oncogene.

Expression of ras oncogenes in NIH 3T3 fibroblasts results in the acquisition by these cells of an invasive potential concomitant with the appearance of cell surface asparagine-linked complex-type glycan structures of a higher average molecular weight (Bolscher, J.G. M., van der Bijl, M. M. W., Neefjes, J. J., Hall, A., Smets, L.A., and Ploegh, H.L. (1988) EMBO J. 7, 3361-3368). We have investigated the enzymatic basis for the altered glycosylation by assessing the activities of all major Golgi glycosyltransferases involved in the synthesis of these structures. Use was made of a stable transfectant cell line (T15) containing the N-ras-protooncogene under the control of a glucocorticoid-inducible mouse mammary tumor virus promoter. Upon induction of the ras gene with dexamethasone: 1) the levels of N-acetylglucosaminyltransferase I and II were essentially unaltered, indicating an unaffected potential to synthesize complex-type glycans; 2) the activities of the branching N-acetylglucosaminyltransferase III and V were elevated 2- to 2.5-fold suggesting the formation of increased amounts of bisected glycans and of structures carrying a Gal beta 1----GlcNAc beta 1----6Man-branch; 3) the levels of the elongating beta 4-galactosyltransferase and beta 3-N-acetylglucosaminyl-transferase were increased 5- to 7-fold indicating a strongly enhanced capacity to synthesize polylactosaminoglycan chains; 4) the level of the major chain-terminating enzyme, alpha 3-galactosyltransferase, was slightly decreased (0.7-fold), whereas those of the alpha 3- and alpha 6-sialyltransferases were slightly elevated (1.3- and 2-fold, respectively), suggesting a shift from termination by alpha-galactosyl residues to termination by sialic acid moieties. Studies on the acceptor specificities of the different glycosyltransferases indicate that these changes occur in a coordinated manner in which the effects of altered glycosyltransferase expression levels amplify each other. Analysis of the size of cell surface complex-type glycopeptides before and after digestion with neuraminidase and endo-beta-galactosidase suggested an increased sialic acid density, an increase in the number and/or length of polylactosaminoglycan chains, and an increased branching of the glycans upon N-ras induction. The enzymatic results explain these structural changes and allow us to define the alterations in glycosylation pathways associated with ras expression.     

IL-1 serves as a secondary signal for IL-9 expression.

IL-9 is produced in vitro by activated CD4+ T cell lines of the Th2 subtype and by naive CD4+ T cells. Here we show that T cell lines stimulated with Con A in the presence of accessory cells (AC) such as irradiated spleen cells or bone marrow-derived macrophages produced substantially more IL-9 than T cells stimulated with Con A alone. These data suggest that AC influence the production of IL-9 through accessory signals that result in an at least 10-fold increase of IL-9 secretion by the respective T cells. Addition of IL-1 to T cells activated by Con A, PHA, or anti-CD3 antibodies revealed that this monokine was responsible for the potentiation of IL-9 production. This finding was confirmed by applying anti-IL-1 antibodies. The production of other lymphokines, namely, IL-3, IL-4, and IL-6, by activated T cells was not or only marginally enhanced in the presence of AC or IL-1, thus indicating that the synthesis of IL-9 is regulated differently from that of other Th2-derived lymphokines. Furthermore, it was demonstrated by Northern blot analysis that IL-1 increases IL-9 expression at the pretranslational level. Because IL-1 alone failed to induce the production of IL-9 by T cells, this monokine acts as a costimulator in combination with a T cell receptor-mediated signal.     

Binding of corticosteroid receptors to rat hippocampus nuclear matrix.

In rat hippocampus, the mineralocorticoid receptor and the glucocorticoid receptor bind corticosterone with high affinity. We have studied the association of these receptors with the nuclear matrix both after in vivo and in vitro administration of radiolabelled corticosterone to hippocampus cells. It was found that in vivo 100% and in vitro 60% of the corticosterone that specifically bound to rat hippocampus nuclei was attached to the nuclear matrix. A selective glucocorticoid receptor agonist did not compete for corticosterone binding. This indicates that this binding was mediated by the mineralocorticoid receptor rather than the glucocorticoid receptor.     

Endogenous Cytokinins in Bougainvillea ;San Diego Red': I. OCCURRENCE OF CYTOKININ GLUCOSIDES IN THE ROOT SAP

Using chromatographic, chemical, and enzymic techniques, 11 compounds capable of stimulating the division of soybean callus cells were tentatively identified in the root sap of Bougainvillea `San Diego Red.' These cytokinin-like compounds included phosphorylated and glucosylated forms of zeatin, ribosylzeatin, and their dihydro derivatives. In addition, isopentenyl adenosine and isopentenyl adenine were apparently also present. The occurrence of glucosylated derivatives in the root sap of plants has not been substantiated previously.     

Measurement of energy expenditure in humans by doubly labeled water method

The utility of the doubly labeled water method for the determination of energy expenditure and water output was investigated in humans. Approximately 10 g of 18O and 0.5 g of 2H as water was orally administered to four healthy adults. Total body water was determined from the isotope dilution, and the ensuing 18O and 2H disappearance rates from body water were determined for 13 days by mass spectrometric isotope ratio analysis of the urinary water. During this period, subjects were maintained on a measured diet to determine energy and water intake. The energy expenditure from the doubly labeled water method differed from dietary intake plus change in body composition by an average of 2%, with a coefficient of variation of 6%. The water outputs determined by the two methods differed by 1%, with a coefficient of variation of 7%. The doubly labeled water method is noninvasive, and the subjects could maintain their daily activities without restriction.     

Diversity of food beans in Kenya

In order to have the consumers’ preferences in Kenya in beans (Phaseolus vulgaris L.) more clearly outlined and to survey the variation existing in local food bean material, 997 seed samples from plants selected in farmers’ fields and from agricultural shows were investigated and classified on the basis of colour, size and shape. For the classification a new number system was used to enable easy data transfer to punch cards. This exercise was primarily carried out to aid in setting the goals for a breeding and selection programme. Of the 997 samples the ten most common types were identified, and among those the Rose cocos occurred most frequently with 36.5%, second were the Canadian wonder types with 13.1%, followed by a Red haricot with 9.2%, Mwezi moja with 9.0% and Mwitemania with 2.4%. The types differed considerably, indicating that consumers’ preferences are very flexible. Personal communications lead to the same conclusion. Therefore a breeding and selection programme has, within certain wide limits, allowance to rank characters like disease and drought resistance higher in importance than seed type.