The fate of aniline, a representative of arylamine pollutants derived from the manufacture of dyes, coal liquefaction, and pesticide degradation, was comprehensively evaluated by use of unpolluted and polluted pond water as model environments. Evaporation plus autoxidation proved to be minor elimination mechanisms, removing ca. 1% of the added aniline per day. Instantaneous binding to humic components of a 0. 1 % sewage sludge inoculum removed 4%. Biodegradation of aniline in pond water was accelerated by the sewage sludge inoculum. A substantial portion of the degraded aniline carbon was mineralized to CO2 within a 1-week period, and microbial biomass was formed as a result of aniline utilization. Biodegradation was clearly the most significant removal mechanism of polluting aniline from pond water. A gas chromatographic-mass spectrometric analysis of biodegradation intermediates revealed that the major pathway of aniline biodegradation in pond water involved oxidative deamination to catechol, which was further metabolized through cis,cis-muconic, beta-ketoadipic, levulinic, and succinic acid intermediates to CO2. Minor biodegradation pathways involved reversible acylation to acetanilide and formanilide, whereas N-oxidation resulted in small amounts of oligomeric condensation products.

Glycoprotein hormone ␣ subunit, in its free form (free ␣), is a major placental product. Its glycosylation was found to change dramatically during the advancement of pregnancy. In this study, we have analyzed these glycosylation changes in five normal pregnancies. Binding to Lens culinaris lectin increased dramatically in all subjects between weeks 14 and 17 from the last menstrual period, indicating more core fucosylation as well as possible changes in branching of glycans. Studies using Datura stramonium agglutinin confirmed that the type of triantennary branching changed in this period of pregnancy. The precise structural nature of these changes was determined by high-pH anion-exchange chromatography and electrospray ionization mass spectrometry. Amounts of core fucosylation and of triantennary glycans increased substantially from early to late second trimester, and a shift was observed from 134/ 133-toward predominantly 136/136-branched triantennary structures. The glycosylation changes occurred in all five individuals at the same time period in gestation, suggesting developmental regulation of N-acetylglucosaminyltransferases IV and V and ␣6-fucosyltransferase during normal pregnancy. These enzymatic activities also appear to be affected in malignant transformation of the trophoblast. Our findings have important implications for the proposed use of specific forms of glycosylation as markers for cancer, as the relative amounts of these glycans in normal pregnancy will be determined by gestational age.Glycoprotein hormone ␣ subunit is common to the heterodimeric hormones chorionic gonadotropin, luteinizing hormone, follicle-stimulating hormone, and thyroid-stimulating hormone. However, in its free form (free ␣ subunit), it is an important placental (1, 2) and pituitary (3) product, and it has been shown to have functions that are independent of the dimeric hormones (4 -7). Glycosylation of free ␣ differs from glycosylation of the combined form (8, 9). The combination of ␣ and ␤ for heterodimer formation takes place in the endoplasmic reticulum prior to processing of the immature glycans. In ␣ subunits that have not combined with a ␤ subunit, enzymes from the post-translational glycosylation machinery have access to substrate sites that are normally protected by the ␤ subunit of the heterodimer. As a result, the free form of ␣ subunit generally contains more elaborate oligosaccharide branching as well as higher amounts of core fucosylation than ␣ subunit obtained from dissociated hormone (8, 9). These characteristic glycosylation patterns prevent secreted free ␣ subunits from combining with ␤ subunits that might be encountered extracellularly, thus ensuring a population of free ␣ molecules (9, 10).The structural diversity of complex-type N-linked glycans is initiated by GlcNAc branching of the trimannosyl core and continues with the action of different glycosyltransferases that further extend these antennae (11). Specifically, the activity of N-acetylglucosaminyltransferase IV initiates the 134/133-branch of c...

No abstract

No abstract

No abstract