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Pyrimidine Biosynthesis in the Genus Streptomyces : Characterization of Aspartate Transcarbamoylase and Its Interaction with Other Pyrimidine Enzymes (open access)

Pyrimidine Biosynthesis in the Genus Streptomyces : Characterization of Aspartate Transcarbamoylase and Its Interaction with Other Pyrimidine Enzymes

Aspartate transcarbamoylase (ATCase) of Streptomyces was characterized and its interaction with other pyrimidine enzymes explored.
Date: May 1998
Creator: Hughes, Lee E. (Lee Everette)
System: The UNT Digital Library
Radial Compression High Performance Liquid Chromatography as a Tool for The Measurement of Endogenous Nucleotides in Bacteria (open access)

Radial Compression High Performance Liquid Chromatography as a Tool for The Measurement of Endogenous Nucleotides in Bacteria

High performance liquid chromatography was used to measure ribonucleoside triphosphates in microbial samples. Anion exchange columns in a radial compression module were used to separate and quantify purine and pyrimidine ribonucleotides. Endogenous ribonucleoside triphosphates were extracted from Escherichia coli and pseudomonas aeruginosa using three different solvents, namely trifluorocetic acid (TFA; 0.5M), trichloroacetic acid (TCA; 6 per cent w/v) and formic acid (1.0M) Extracts were assayed for uridine 5'-triphosphate (ATP), and guanosine 5'-triphosphate (GTP) by using anion exchange radial compression high performance (pressure) liquid chromatography. The three extraction produres were compared for yield of triphosphates. E. coli, the TFA extraction procedure was more sensitive and reliable than TCA and formic acid extraction procedures, but , in P. aeruginosa, the best yields of ATP and GTP were obrained following extraction with TFA. Yields of UTP and CTP increased when extraction was performed in TCA. These data illustrate that different extraction produres produce different measures for different triphosphates, a point often overlooked.
Date: August 1986
Creator: Dutta, Probir Kumar
System: The UNT Digital Library
Effects of Water Quality, Instream Toxicity, and Habitat Variability on Fish Assemblages in the Trinity River, Texas (open access)

Effects of Water Quality, Instream Toxicity, and Habitat Variability on Fish Assemblages in the Trinity River, Texas

The Trinity River flows through the Dallas-Ft. Worth Metroplex in north central Texas where it receives effluents from numerous point sources including seven large regional wastewater treatment facilities. Historically, the Trinity River has been impacted by massive wastewater loadings which often constitute > 80% of the total river discharge during low flow periods. Normally, high mass loadings correspond to the summer months, compounding the effects of a naturally stressful period, characterized by high temperatures and low dissolved oxygen concentrations. Samples from 12 stations were collected quarterly over an 18 month period from the Trinity River and two tributaries. Water samples were analyzed for a variety of water quality variables, including metals, priority pollutants, pesticides, and general water quality parameters. Water samples were also tested for acute and subchronic effects with several test species. Fish were collected at each station and assemblages were characterized using traditional classification techniques and the Index of Biotic Integrity. In addition, sediment samples were assessed for toxic effects which could have adversely impacted fish recruitment and in situ biomonitoring experiments were performed. Quantitative habitat characterization analyses were performed to gain additional information that could possibly explains differences in fish assemblage structure related to habitat variability. Data …
Date: December 1989
Creator: Arnold, Winfred R., 1960-
System: The UNT Digital Library