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1.
Modification of nuclear and cytosolic proteins by O-linked N-acetylglucosamine (O-GlcNAcylation) is ubiquitous in cells. The in vivo function of the protein O-GlcNAcylation, however, is not well understood. Here, we manipulated the cellular O-GlcNAcylation level in Drosophila and found that it promotes developmental growth by enhancing insulin signaling. This increase in growth is due mainly to cell growth and not to cell proliferation. Our data suggest that the increase in the insulin signaling activity is mediated, at least in part, through O-GlcNAcylation of Akt. These results indicate that O-GlcNAcylation is one of the crucial mechanisms involved in control of insulin signaling during Drosophila development.  相似文献   

2.
Summary In case ofAbsidia coerulea, Mucor mucedo, Rhizopus nodosus, Rhizopus oryzae andRhizopus suinus (auxoautotroph), Hypoxanthine effects, as well as in case ofPhycomyces Blakesleeanus (auxo-heterotroph), by acceleration of the germinating of the spores a temporary increased growth in contrary to controls without this additional growth factor.  相似文献   

3.
Summary Halocyamine A, an antimicrobial substance isolated from hemocytes of the solitary ascidianHalocynthia roretzi, inhibited in vitro the growth of fish RNA viruses (infectious hematopoietic necrosis virus and infectious pancreatic necrosis virus). Pretreatment of RNA virus with halocyamine A reduced the infectivity of the virus toward host cells. The growth of marine bacteria,Achromobacter aquamarinus andPseudomonas perfectomarinus, was also inhibited by halocyamine A but that ofAlteromonas putrefaciens andVibrio anguillarum was not. These results suggest that halocyamine may have a role in the defense mechanisms ofH. roretzi against marine viruses and bacteria.  相似文献   

4.
Recent discoveries revealing that carbohydrate modifications play critical roles in a wide variety of biological processes have brought wide recognition to the field of glycobiology. Growing attention has focused on the function of unusual O-linked carbohydrate modifications such as O-fucose. O-fucose modifications have been described in several different protein contexts, including epidermal growth factor-like repeats and thrombospondin type 1 repeats. The O-fucose modifications on thrombospondin type 1 repeats have only recently been described, but the site of modification occurs in a region proposed to play a role in cell adhesion. O-fucose modifications on epidermal growth factor-like repeats have been described as important players in several signal transduction systems. For instance, Notch, a cell-surface signaling receptor required for many developmental events, bears multiple O-fucose saccharides on the epidermal growth factor-like repeat of its extracellular domain. The O-fucose moieties serve as a substrate for the β1,3 N-acetylglucosaminyltransferase activity of Fringe, a known modifier of Notch function. The alteration of O-fucose structures by Fringe influences the ability of Notch ligands to activate the receptor and provides a means to regulate Notch signaling. Thus, O-fucose and Fringe provide a clear example of how carbohydrate modifications can have direct functional consequences on the proteins they modify. RID="*" ID="*"Corresponding author.  相似文献   

5.
Summary A new group of iron-containing metabolites, with growth stimulating properties for a number of microorganisms, has been isolated from streptomycetes and namedferrioxamines. It is proposed to include them, together with some known substances, like ferrichrome, coprogen and the terregens factor, which either contain or bind iron, in a new class of growth factors, thesideramines.The biological property of the sideramines is counteracted by iron-containing antibiotics from streptomycetes, thesideromycins. They comprise, besides known products like grisein and albomycin, two new groups of antibiotics, among them the highly potentferrimycins.

22. Mitteilung, Stoffwechselprodukte von Actinomyceten; 21. Mitteilung: Helv. chim. acta43, im Druck (1960).  相似文献   

6.
Summary In experiments on the influence of microscopic capillaries on the growth ofEscherichia coli, Brevibacterium linens, Micrococcus flavus andBacillus cereus, a distinet delay in growth was observed. The difference in counts was greatest after 8 h. Later a slight equilibration of counts was noted. WithB. cereus, only slight or no spore formation was observed under microcapillary conditions.Acknowledgment. The author would like to thank Mr. Theo Wihan for his excellent technical assistance.  相似文献   

7.
Summary Oxythiamine reversed the growth inhibition ofSaccharomyces cerevisiae caused by pyrithiamine, although oxythiamine alone inhibited yeast cell growth. This phenomenon was explained by thiamine production from these 2 thiamine antagonists which was demonstrated using cell suspensions and the crude extract ofS. cerevisiae.  相似文献   

8.
Summary Several quassinoids, obtained by isolation and derivatization fromSimaba multiflora andSoulamea soulameoides, were evaluated for growth inhibitory and insecticidal effects against the tobacco budworm (Heliothis virescens) and for antifeedant effects againstH. virescens and the fall armyworm (Spodoptera frugiperda). The relative activity of the quassinoids as insect growth inhibitors generally paralleled their known relative potency as antileukemic and cytotoxic agents.Phytochemical aspects of this work were supported by Contract CM-97295 with the Division of Cancer Treatment, National Cancer Institute, National Institutes of Health, Bethesda, Md. Insects were kindly supplied by the agency of the United States Department of Agriculture at Brownsville, TX.  相似文献   

9.
Methanohalophilus mahii SLP andMethanohalophilus halophilus Z-7982, two closely-related, moderately halophilic, methylotrophic methanogens, were tested for their adaptation to saline conditions. They grew in a wider range of salinities than previously reported, in a defined medium with as little as 0.1 M NaCl, and with a high as 4.0 M NaCl forM. halophilus and 4.5 M NaCl forM. mahii. Fastest growth occurred with 1.5 M NaCl forM. mahii and 1.0 M NaCl forM. halophilus. M. mahii also grew in media in which NaCl was replaced by sucrose or KCl as osmolytes up to the osmolal equivalent of 2 and 2.5 M NaCl (these media contained other sodium salts totaling about 0.1 M Na+). In media with either sucrose of KCl replacing NaCl,M. mahii grew fastest at osmolalities approximately equiosmolal to 1 M NaCl.M. mahii not only grew well at a wide range of osmosities, it also tolerated rapid shifts in osmolality. Cells subjected to a rapid 10-fold hypertonic shift resumed growth without a prolonged lag. When cells were subjected to a rapid 10-fold hypotonic shift, 90% of cells lysed, but the remaineder continued to swell with little further lysis during the next 45 min. Surviving cells resumed growth.Methanohalophilus strains grown in defined medium had low cytosolic Na+ concentrations; K+ concentrations were as high as 0.35 M. Organic osmotica in the cytosol include glycine betaine and larger amounts of N,N-dimethylglycine.  相似文献   

10.
Summary To control the growth of eurocaryotic and blue-green algae in anaerobic reactors of photosynthetically grown Rhodospirillaceae, the effect of algae inhibitors with different modes of action was examined. Tests were performed with mixed populations of green algae and blue-green algae, besides strains of the purple nonsulphur bacteriaRhodopseudomonas capsulata, Rhodospirillum rubrum andRhodomicrobium vannielii. Chloroxuron, a urea-derivative, was found to inhibit completely growth of green and blue-green algae at 5 ppm. When it was applied to the Rhodospirillaceae cultures, growth was not reduced and nitrogenase activity was not inhibited.  相似文献   

11.
The influence of mycorrhizal colonization withGlomus mosseae on parameters of N2 fixation and plant growth was studied in pot experiments with pea plants (Pisum sativum L.) infected withRhizobium leguminosarum and supplied with varied levels of phosphorus (P) and nitrogen (N). Reduced light intensities were used to evaluate the dependence of the microsymbionts on assimilate supply. In plants grown with low P supply, mycorrhization increased the concentration of P in shoots, and thus N2 fixation. Reduced light intensity significantly depressed mycorrhizal colonization and nodule growth in low-P plants. When P supply did not limit plant growth and N2 fixation, however, the percentage of mycorrhizal colonization was reduced due to the higher P status, and the microsymbionts were not impaired by low light intensities. To maximize carbohydrate supply, another experiment was carried out at high light intensity of 900 mol m–2s–1 and with non-limiting P supply. Nitrogen fertilization, given as starter N, enhanced plant growth, but delayed nodule formation. Towards flowering, nodulation rapidly increased, but less so inGlomus inoculated plants. After 28 days mycorrhizal plants were lower in shoot dry weight, nodule dry weight and nitrogenase activity. The results suggest that under many, but not all, environmental conditions the host plant is able to restrict mycorrhizal colonization and, thus, to prevent impairment ofRhizobium symbiosis.deceased in May 1994  相似文献   

12.
Summary A decrease in growth rate of the antennal bud by means of colchicine deflects the differentiation of theAristopedia antenna towards an arista.

DieDrosophilamutanteAristopedia unterscheidet sich von der Wildform durch die Umwandlung der Fühlergeißel (=Arista) in einen Fuß.  相似文献   

13.
The product of the MDR1 gene (P-gp) has been implicated in the transport of cholesterol from plasma membrane to endoplasmic reticulum for esterification. In previous studies on leukemia cell lines, we suggested that cholesterol esterification may regulate the rate of cell growth and that the MDR1 gene might be involved in this process by modulating intracellular cholesterol esters levels. To further investigate this matter, the rate of cell growth, cholesterol metabolism, expression of the MDR1 gene, and P-gp activity were compared in KB cell lines displaying differences in expression and function of P-gp (drug-sensitive phenotype versus MDR phenotype). The rate of cell growth correlated with cholesterol esterification in all KB cell lines, whereas the over-expression of MDR1 observed in the MDR cell lines was not always associated with an increased capacity of cells to esterify cholesterol. Two known inhibitors of P-gp activity, progesterone and verapamil, strongly inhibited both cholesterol esterification and cell proliferation in all KB cell lines, but they affected intracellular accumulation of labeled vinblastine only in MDR cell lines. These results further support a role for cholesterol esters in the regulation of cell growth and suggest that the P-gp expressed in MDR KB cells is not involved in the general process leading to cholesterol esterification. Received 14 February 2000; received after revision 10 April 2000; accepted 8 May 2000  相似文献   

14.
Summary In shoots ofLinum perenne apical growth was observed at both ends of the fibres. Their rounded tips, rich in protoplasm, protude into the middle lamellae of adjacent fibres or parenchyma cells. In addition to their apical growth, the fibre walls undergo symplastic growth with the walls of neighbouring cells. The formation of the pointed ends of fully developed fibres is described.  相似文献   

15.
Summary Lipopolysaccharides (LPS) from variousRhodopseudomonas andRhodospirillum species were tested for their radioprotective efficiency against X-irradiation and for their influence on the growth of spleen colony forming units (CFU-s) in mice. The LPS fromRhodopseudomonas gelatinosa Dr2 gave a high survival rate. It also favoured CFU-s formation and erythroid differentiation.  相似文献   

16.
Investigations into mechanisms that restrict the recovery of functions after an injury to the brain or the spinal cord have led to the discovery of specific neurite growth inhibitory factors in the adult central nervous system (CNS) of mammals. Blocking their growth-suppressive function resulted in disinhibition of axonal growth, i.e. growth of cultured neurons on inhibitory CNS tissue in vitro and regeneration of injured axons in vivo. The enhanced regenerative and compensatory fibre growth was often accompanied by a substantial improvement in the functional recovery after CNS injury. The first clinical studies to assess the therapeutic potential of compounds that neutralize growth inhibitors or interfere with their downstream signalling are currently in progress. This review discusses recent advances in the understanding of how the ‘founder molecule’ Nogo-A and other glialderived growth inhibitors restrict the regeneration and repair of disrupted neuronal circuits, thus limiting the functional recovery after CNS injuries. Received 5 April 2007; received after revision 28 September 2007; accepted 1 October 2007  相似文献   

17.
Summary 3 strains of soil bacteria (2Achromobacter, 1Flavobacterium) were isolated by growth on cyclo(Gly-L-Pro) as carbon/nitrogen source. Good growth required yeast extract supplements. Utilization of cyclo(Gly-L-Pro) was inducible. Many efforts failed to obtain active cell-free preparations. Injected radioactive cyclo(Gly-L-Pro) was excreted intact by the albino rat; in contrast, injected radioactive H-Gly-L-Pro-OH was extensively metabolized.Supported by Grant GM-11105 from the National Institutes of Health.  相似文献   

18.
Summary The administration of ethionin to tissue cultures of fibroblastsin vitro causes a rapid and total inhibition of the growth of the transplanted tissues.It was observed that equimolar quantities of methionin are, on the contrary, well tolerated. The inhibition is therefore seen to be due to the dismetabolic activity of the antagonist.The contemporary administration of cholin is not able to restore the growth capacity of ethionin inhibited tissue cultures.In conclusion, ethionin produces a direct action on fibroblastsin vitro, probably intervening in the process of protein synthesis of the transplanted elements.  相似文献   

19.
Summary The amino acid requirements for moulting, growth and development ofDysdercus similis have been investigated. The insects could not moult and reach maturity when given 10 essential amino acids only. However, if these were supplemented either with glutamic acid, glycine or aspartic acid growth and moulting was found to be normal.Dysdercus has an unusual synthetic mechanism for converting tyrosine into phenylalanine.The author is grateful to Prof.R. S. Saini for his guidance, critical discussions and encouragement.  相似文献   

20.
Summary A spontaneous mutant ofP. anserina isolated by screening for benomyl resistance exhibited a diurnal growth rhythm dependent on light-dark cycles. The rhythmic character, the benomyl resistance and a growth rate reduced to 50% of that of the wild type were inherited together over more than 10 generations. The locus was mapped on linkage group II, 0.35 map units distal to the locusz (=0.81 map units from the centromere).  相似文献   

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