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At least 703 records · Page 39Linked to original sources
PubMed1989

Requirement of upstream activation sequences for nitrogen catabolite repression of the allantoin system genes in Saccharomyces cerevisiae.

Synthesis of the transport systems and enzymes mediating uptake and catabolism of nitrogenous compounds is sensitive to nitrogen catabolite repression. In spite of the widespread occurrence of the control process, little is known about its mechanism. We have previously demonstrated that growth of cells on repressive nitrogen sources results in a dramatic decrease in the steady-state levels of mRNA encoded by the allantoin and arginine catabolic pathway genes and of the transport systems associated with allantoin metabolism. The present study identified the upstream activation sequences in the 5'-flanking regions of the allantoin system genes as the cis-acting sites through which nitrogen catabolite repression is exerted.

Allantoin↗
PubMed2001

Microbial community analysis in the denitrification process of saline-wastewater by denaturing gradient gel electrophoresis of PCR-amplified 16S rDNA and the cultivation method.

The metallurgic wastewater generated from the processes of recovering precious metals from industrial wastes contains high concentrations of nitrogen compounds and salts. Biological nitrogen removal from this wastewater was attempted using a circulating bioreactor system equipped with an anaerobic packed bed or an anaerobic fluidized bed. The denitrification capability of the system with the anaerobic packed bed was more stable than that of the system with the anaerobic fluidized bed. The NOx removal rate of the anaerobic packed bed was as high as 97%. Microbial community analysis by denaturing gradient gel electrophoresis (DGGE) of PCR-amplified 16S ribosomal DNA (rDNA) fragments and the cultivation method revealed that the community diversity varied in accordance with wastewater composition such as the level of salinity and so on. Phylogenetic analysis suggested that the taxonomic affiliation of the dominant species in the anaerobic reactors was to the gamma-Proteobacteria including Halomonadaceae species. The PCR-DGGE method as a non-cultivation method was found to be a powerful tool for analysis of the microbial community, because the cultivation method could detect only a fraction of the microbial species present in these systems. The genetic diversity of the isolated bacteria belonging to the gamma-Proteobacteria which reduced both nitrate and nitrite in the anaerobic packed bed was higher than that of the bacteria in the anaerobic fluidized bed. This suggested that a genetically diverse microbial community stabilized the denitrifying performance in the anaerobic packed bed.

Journal Article↗
PubMed1981

Comparison of the disposition of several nitrogen-containing compounds in the sea urchin and other marine invertebrates.

1. The disposition of an aromatic amine and three aromatic nitro compounds was investigated in the sea urchin, Strongylocentrotus purpuratus. 2. The sea urchin rapidly eliminated injected compounds. The elimination rate constants decreased in the order p-toluidine greater than p-nitroanisole = p-nitrophenol greater than p-nitrotoluene. The fraction of total injected compound eliminated in 8 h was lowest for p-nitrophenol less than p-toluidine less than p-nitrotoluene less than p-nitroanisole. 3. Biotransformation for the sea urchin was primarily reduction of the nitro group followed by acetylation of the amine. 4. Other animals, starfish (Pisaster ochraceus), sea cucumber (Cucumaria miniata), gum boot chiton (Cryptochiton stelleri) and mussels (Mytilus californianus), injected with p-nitroanisole exhibited a trend toward oxidative biotransformation. 5. Elimination of parent compound was the major pathway for reducing body burden of xenobiotics for the invertebrates studied. 6. p-Toluidine oxidizes during analysis and was thus not suitable for studying biotransformation.

Amines↗
PubMed1976

Effect of certain nitrogenous heterocyclic compounds on carotenogenesis in Verticillium agaricinum.

Pyridine, isonicotinoylhydrazide and 1-methylamidazole have been used to investigate carotenoid biosynthesis in V. agaricinum. The results suggest that both torulin (C40) and neurosporaxanthin (C35) are formed from the precursors phytoene and phytofluene. These was no evidence of lycopene accumulation under these conditions. After 4 days' growth in the presence of isocotinolyhydrazine the fungus contained torulin and neurosporaxanthin only, whereas after 7 days, seven other carotenoids appeared as well, some of which were at the early stages of carotenoid biosynthesis. There results cannot be explained on the basis of a system consisting of free enzymes but of an enzyme aggregate already proposed for Phycomyces.

Carotenoids↗
PubMed2000

Nitrogen bridgehead compounds, facile synthesis of bioactive cyanopyrimido[1,2-a]pyrimidinones.

Synthesis of some new cyanopyrimido[1,2-a]pyrimidinones 5-22 have been achieved via interaction of 2-amino-6-anisyl-5-cyano-4(3H)-pyrimidinone (1) with some heterocycles having a vicinal chloroester, chlorocyano or mercaptocyano group, dimethyl acetylenedicarboxylate, active methylene compounds, ethyl 2-acetyl-3-anisylpropenoate, ethyl 3-aryl-3-cyanopropenoates, ethyl 2-cyano-3-ethoxyacrylate and some enones or enals. Some of the isolated products were subjected to biological screening tests.

Absidia↗
PubMed1975

[Research on nitrogen heterocyclic compounds. IX. Synthesis of 5-hydroxy-2,4-dicarbethoxypyrroles].

Reaction between diethyl ethoxymethylenemalonate and N-substituted diethylaminomalonates in the presence of sodium ethoxide gives 5-hydroxy-2,4-dicarbethoxypyrroles. By treating these compounds with acetic anhydride we shall get the corresponding 5-acethoxy-2,4-dicarbethoxypyrroles and, by catalytic reduction, the corresponding 2,4-dicarbethoxy-5-pyrrolidinones, which in turn are hydrolyzed to the well known corresponding pyroglutamic acids. The I.R. and N.M.R. spectral data are in agreement with the proposed structures.

Indicators and Reagents↗
PubMed2005

[Effect of oxygen and nitrogen active compounds on pH value in myometrium myocytes].

In suspension from a rat uterus using fluorescent pH1 probe BCECF-AM was established that the "apparent" pH1 value for this object was 6.72 +/- 0.02 at pHo = 7,4 (t = 25 degrees C, n = 5). Cell activation by 0.1 mM carbachol was accompanied by a rise in cytosolic pH up to 6.81 +/- 0.01. This process with different efficiency was inhibited by blockers of K(+)- and H(+)-channels: 0.1 mM 4-amidopyridine, tetraethilamonium and cadmium. The blockers of passive H(+)-transport do not inhibit completely alkalization of myoplasm that can testify in the favor of the non-channel way of passive transport H+ through plasmalemma. It was established that NO (0.1 mM sodium nitroprusside) and NO2- (10 nM) significantly enhanced the carbochol-induced rise of myoplasm pH in the cells from myometrium. It also was shown that carbachol-induced pH. in myocytes was increased by the addition of 10 nM H2O2. It was suggested that the studied compounds could influence Ca2+ transport systems by changing pH in myocytes.

Animals↗