UNT Libraries - 17 Matching Results

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

Description: 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, characteri… more
Date: December 1989
Creator: Arnold, Winfred R., 1960-
Item Type: Refine your search to only Thesis or Dissertation
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Interactions between Carotid and Cardiopulmonary Baroreceptor Populations in Men with Varied Levels of Maximal Aerobic Power

Description: Reductions in baroreflex responsiveness have been thought to increase the prevalence of orthostatic hypotension in endurance trained athletes. To test this hypothesis, cardiovascular responses to orthostatic stress, cardiopulmonary and carotid baroreflex responsiveness, and the effect of cardiopulmonary receptor deactivation on carotid baroreflex responses were examined in 24 men categorized by maximal aerobic power (V02max) into one of three groups: high fit (HF, V0-2max=67.0±1.9 ml•kg^-1•min^… more
Date: August 1989
Creator: Pawelczyk, James A. (James Anthony)
Item Type: Refine your search to only Thesis or Dissertation
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The Stoneflies (Plecoptera) of the Ozark and Ouachita Mountains

Description: Collections of stoneflies (Plecoptera) were made at 603 stream sites from Nov. 1983 - May 1988 in the Ozark-Ouachita Mountain region, in relation to physiographic and vegetational characteristics. Examination of approximately 9000 vials from these collections, supplemented with material from major museums and other collectors, revealed 88 stonefly species in 8 families and 24 genera. Pearson's measure of association (R) showed there was a significant association between species present and eac… more
Date: December 1989
Creator: Poulton, Barry C. (Barry Charles)
Item Type: Refine your search to only Thesis or Dissertation
open access

Systematics of Coccidian Parasites (Apicomplexa) from Amphibians and Reptiles in Northcentral Texas

Description: Between February 1986 and October 1988, 863 amphibians and reptiles were collected in northcentral Texas and examined for coccidial parasites. Thirteen percent of amphibians <26% salamanders, 11% frogs and toads) and 28% of reptiles (54% turtles, 25% snakes) harbored 20 previously described and 16 new species of coccidia; overall prevalence of infection was 176/863 < 20%). Sixteen Ambvstoma texanum were infected with Eimeria ambystomae which represents new host and geographic locality records f… more
Date: December 1989
Creator: McAllister, Chris Thomas
Item Type: Refine your search to only Thesis or Dissertation
open access

Pyrimidine Metabolism in Rhizobium: Physiological Aspects of Pyrimidine Salvage

Description: The objective of this research was to study the pyrimidine salvage pathways of Rhizobium. Three approaches were used to define the pyrimidine salvage pathways operative in two species of Rhizobium, R. meliloti and R. leguminosarum . The first approach was to ascertain the pyrimidine bases and nucleosides that could satisfy the pyrimidine requirement of pyrimidine auxotrophs. Uracil, cytosine, uridine or cytidine all satisfied the absolute pyrimidine requirement. The second approach was to selec… more
Date: December 1989
Creator: Ibrahim, Mohamed M.
Item Type: Refine your search to only Thesis or Dissertation
open access

Toxicological Characterization of Trinity River Sediments

Description: Sediments in the Trinity River were chemically, physically and biologically characterized and assessed for toxicity. Laboratory bioassays were conducted to identify sediments which induced toxic responses in test organisms and to document these responses through time. Metal and organic contaminant concentrations in bottom sediments were measured. Relationships between these concentrations and biological responses observed in laboratory bioassays were determined. Toxicity identification / reduct… more
Date: December 1989
Creator: Hall, Jerry F. (Jerry Fowler)
Item Type: Refine your search to only Thesis or Dissertation
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Measurement of Feedback Inhibition In Vivo and Selection of ATCase Feedback Altered Mutants in Salmonella typhimurium

Description: Aspartate transcarbamoylase (ATCase; encoded by pyrBI genes) is one of the most studied regulatory enzymes in bacteria. It is feedback inhibited by cytidine triphosphate (CTP) and activated by adenosine triphosphate (ATP). Much is known about the catalytic site of the enzyme, not nearly as much about the regulatory site, to which CTP binds. Until now a positive selection for feedback-modified mutants was not available. The selection we have developed involves the use of a pyrA deletion in S. ty… more
Date: August 1989
Creator: Bailey, Andrea J., 1952-
Item Type: Refine your search to only Thesis or Dissertation
open access

Validation of a Coupled Herbicide Fate and Target Plant Species Effects Model

Description: A series of experiments provided data to parameterize and validate a coupled herbicide fate and target plant species effects model. This simulation model is currently designed to predict responses of water hyacinth populations to treatments of the dimethylamine formulation of 2,4- dichloro-phenoxy acetic acid (2,4-D -DMA). Experiments investigated 1) the response of water hyacinth to varying exposures of 2,4-D (DMA); 2) the role of water hyacinth density and herbicide interception in treatment … more
Date: December 1989
Creator: Clifford, Philip A. (Philip Alan)
Item Type: Refine your search to only Thesis or Dissertation
open access

Degradation of Phenolic Acids by Azotobacter Species Isolated from Sorghum Fields

Description: Sorghum plants excrete phenolic acids which reduce subsequent crop yields. These acids accumulate in field soil by combining with soil and clay particles to form stable complexes which remain until degraded by bacterial metabolism. The amount of phenolic acids in soil samples were obtained by gas chromatography measurements, while Azotobacter populations were obtained by plate counts in 40 sorghum field samples from Denton County, Texas. One can conclude that increasing the Azotobacter populati… more
Date: August 1989
Creator: Al-Hadhrami, Mohamed N. (Mohamed Nasser)
Item Type: Refine your search to only Thesis or Dissertation
open access

Sediment Characteristics and Bioavailability of Sorbed Neutral Organic Compounds

Description: Several sediment characteristics were analyzed to determine their suitability for use as potential normalization factors for the bioavailability of neutral organic compounds sorbed to sediments. Percent organic carbon, cation exchange capacity and particle surface area were measured sediment characteristics that varied sufficiently to encompass the range in observed sediment toxicity. Laboratory sediment toxicity test data using fluoranthene suggest that there is no biologically significant cor… more
Date: December 1989
Creator: Suedel, Burton C. (Burton Craig)
Item Type: Refine your search to only Thesis or Dissertation
open access

Interrelational Laboratory Information System for Data Storage and Retrieval

Description: The necessity for a functional user friendly laboratory data management program has become evident as the quantity of information required for modern scientific research has increased to to titanic proportions. The required union of strong computer power, ease of operation, and adaptability have until recently been outside the realm of most research laboratories. Previous systems, in addition to their high cost, are necessarily complex and require software experts in order to effect any changes… more
Date: August 1989
Creator: Gregory, Michael W. (Michael Walter)
Item Type: Refine your search to only Thesis or Dissertation
open access

Two-Dimensional Gel Electrophoresis of in Vivo and in Vitro Synthesized Proteins, Antigenic Proteins, and Cross-Reactive Antigens in Treponema Pallidum Subsp. Pallidum Nichols Strain and Treponema Phagedenis Biotype Reiter

Description: Two-dimensional electrophoretic protein profiles of in vivo and in vitro propagated T.pallidum subsps. pallidum Nichols strain were analyzed and compared. This comparative analysis revealed two in vitro synthesized, cytoplasmic cylinder-associated polypeptides with molecular masses 29.5 and 34.7 kDa, pI 5.62, and one in vitro "lost" polypeptide with molecular mass 34.7 kDa, pI 5.34. integral membrane proteins of in vitro and in vivo propagated T. pallidum was identified by phase partitioning wi… more
Date: May 1989
Creator: Sayahtaheri, Sousan
Item Type: Refine your search to only Thesis or Dissertation
open access

Characterization of the Self-Replicating Kirsten Murine Leukemia Viral DNA: Replication and Tetracycline Resistance

Description: This research project deals with the characterization of self-replicating Kirsten murine viral DNA. The replication of this viral DNA and tetracycline resistance conferred to bacteria by this viral DNA will be studied. The restriction endonuclease and Southern blot analysis revealed a fragment of pBR322 from the Hind III and Pst I site that is located in the 3' end of the MLV-K:E molecule. Single stranded sequencing of the two terminal ends of this fragment verified that the 3' end of MLV-K:E c… more
Date: August 1989
Creator: Najmabadi, Hossein
Item Type: Refine your search to only Thesis or Dissertation
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The Suspension Cultivation of, and the use of Alternative Cell lines for the In Vitro Cultivation of, Treponema Pallidum Subspecies Pallidum

Description: This study had two objectives: to achieve suspension cultivation of Sf1Ep cells and to develop procedures for achieving the replication of T. pallidum in those cell cultures. Sf1Ep cells have been the sole cell line used for the in vitro cultivation of T. pallidum. A study was undertaken to determine if other cell lines can support growth of T. pallidum. Rabbit skin fibroblasts (RAB-9), nude mouse ear (NME) cells, and normal rebbit testis fibroblasts (RT) were compared to Sf1Ep cells for their … more
Date: May 1989
Creator: Riley, Bryan Scott
Item Type: Refine your search to only Thesis or Dissertation
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Suppression of Immune Functions by PCBs in the Earthworm Lumbricus terrestris

Description: This research is part of an effort to develop non-mammalian surrogate immunoessays with the earth worm Lumbricus terrestris to assess immunotoxic potential of xenobiotics to mammals. The objective was to determine if earthworm immunoessays, namely E- and S- rosette formation and phagocytosis, are sensitive to a known mammalian immunotoxin, the PCB Arclor 1254. Results are presented in terms of PCB exposure and tissue concentrations during uptake/depuration.
Date: May 1989
Creator: Rodriguez Grau, Jorge Luis
Item Type: Refine your search to only Thesis or Dissertation
open access

The Teratogenic Effects of Nocodazole and Acrylamide in Mus Musculus

Description: In two separate experiments, weight adjusted doses of nocodazole and acrylamide were injected intraperitoneally at various time intervals into twelve week old female mice. Within the nocodazole experiment, the doses were injected at varying time intervals before and after mating. On day seventeen of gestation, the female mice were sacrificed and their uterine contents examined. Nocodazole induced a significant increase in reproductive pathology per total implants when administered one hour aft… more
Date: May 1989
Creator: Oliva, Jean L. (Jean Louise)
Item Type: Refine your search to only Thesis or Dissertation
open access

Characterization of the Outer Membrane of Treponema Pallidum Subsp. Pallidum by Binding Studies Using Antibodies, Complement, and Host Serum Proteins

Description: The major goal of this study was to achieve sustained cultivation of virulent T. pallidum in vitro. The putatuive binding of host proteins to the outer membrane (OM) of intact, virulent T. pallidum subsp. pallidum has been investigated. A major breakthrough was the development of a filtration assay, usinglow protein-binding membrane filters, for the measurement of substances bound to or incorporated into th eOM of T. pallidum. This avoided the conventional manipulations which can damage the fra… more
Date: December 1989
Creator: Chang, Po-Hsun
Item Type: Refine your search to only Thesis or Dissertation
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