Factors Inhibiting Dissociation Of Neisseria gonorrhoeae Cells (open access)

Factors Inhibiting Dissociation Of Neisseria gonorrhoeae Cells

The initial studies reported in this dissertation were attempts to induce mutations in those genes which control dissociation in cells of Nei sseria gonorrhoeae. These studies led to an investigation of survival curves of cells grown in liquid media. Instead of survival curves reflecting the diploid nature of gonococci, multiple cell kinetics were observed. It was found that large clumps contained a predominance of cells of the T2 type and that when these clumps were dispersed by DNAase, it appeared that dissociation of T2 was inhibited. The notion of a mechanism of T2 to T4 dissociation being due to genetic transformation was disspelled by these data.
Date: August 1982
Creator: Gonzalez, Anthony H.
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Degradation of Humic Substances by Aquatic Bacteria (open access)

Degradation of Humic Substances by Aquatic Bacteria

A variety of aquatic bacteria were isolated and tested for their ability to degrade humic substances and their aromatic residues/monomers which serve as precursors of the trihalomethanes (THMs) found in chlorinated drinking waters. The majority of them were Gram-negative, oxidative types dominated by pseudomonads. Most of the 146 isolates were found to utilize as their sole source of carbon several or more of ten aromatic compounds known to be products of degradation of humus and also to be precursors of THMs. The aromatics tested, with percent of the isolates utilizing the compound in parentheses, were: p-hydroxybenzoate (49), vanillic acid (48), 3,5-dihydroxybenzoic acid (16), syringic acid (19), vanillin (30), benzoic acid (27), ferulic acid (34), resorcinol (9), catechol (8) and protocatechuic acid (27).
Date: August 1985
Creator: Baiu, Saleh Hamed Salem
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Systematics of the Stonefly Tribe Suwalliini Surdick and Behavioral Studies of Selected Species in the Stonefly Families Chloroperlidae and Perlidae (open access)

Systematics of the Stonefly Tribe Suwalliini Surdick and Behavioral Studies of Selected Species in the Stonefly Families Chloroperlidae and Perlidae

The purpose of this study is to revise the genus Suwallia and to evaluate the potential taxonomic importance of adeagal and other genitalic characters, adult pigment patterns and egg characters. The revision concentrates on western North American species while providing coverage of all species, except Suwallia asiatica Zhiltzova and Lavanidova where only presumed females have been available for study. Communication and mate locating behaviors in adult stoneflies are critical for life cycle completion and species perpetuation. Drumming signals are known for numerous species of Plecoptera, but mate searching patterns and specifically, if or how vibrational communication is utilized for locating mates are virtually unknown for all stonefly species. I conducted field or laboratory studies of three species to elucidate mate searching patterns and how vibrational communication is used for locating mates. The species studied included a bushtopper, Suwallia pallidula (Banks); a ground scrambler, Claassenia sabulosa (Banks); and treetopper, Perlinella drymo (Newman). The "fly-tremulate-search". "rock to rock" and "fly-drum-search" search patterns exhibited by these species are described, as well as how vibrational communication is used for mate finding. Vibrational signal production by tremulation is reported for the first time in Suwallia, and for only the second time Plecoptera.
Date: August 1997
Creator: Alexander, Kevin D. (Kevin Dewayne)
Object Type: Thesis or Dissertation
System: The UNT Digital Library
MYB5 and MYB14 Play Pivotal Roles in Seed Coat Polymer Biosynthesis in Medicago truncatula (open access)

MYB5 and MYB14 Play Pivotal Roles in Seed Coat Polymer Biosynthesis in Medicago truncatula

Article discussing MYB5 and MYB14 playing pivotal roles in seed coat polymer biosynthesis in Medicago truncatula.
Date: August 2014
Creator: Liu, Chenggang; Jun, Ji Hyung & Dixon, R. A.
Object Type: Article
System: The UNT Digital Library
Effects of Water Source, Suspended Solids, and Acclimation on Biotransformation of 2 /4-Dichlorophenoxy Acetic Acid in Aquatic Systems (open access)

Effects of Water Source, Suspended Solids, and Acclimation on Biotransformation of 2 /4-Dichlorophenoxy Acetic Acid in Aquatic Systems

In recent years there has been a great deal of scientific interest in processes that affect the fate of organic chemicals in the environment. one main reason for this increased interest is due to greater environmental concern over accidental or purposeful release of these chemicals into the environment by man. A major environmental concern is the increased use of pesticides over the last few years. In the thirty years prior to 1978 the use of pesticides has increased by a factor of forty (Ridgeway et al., 1978). Recently the use of herbicides has been increasing, but that of insecticides has stabilized (Willis, 1983). Detectable amounts of organic pesticides can be found in many areas of the biosphere. For toxic organic chemicals to be used safely, researchers must have a clear understanding of the fate and persistence of these chemicals when they are released into the environment. This understanding will also allow the development of new products that, when properly used, will not produce adverse effects to man or the environment (Weber, 1972). According to the Toxic Substance Control Act (TSCA) any new or expanded-use chemical that might be released into the environment must be tested for environmental hazard.
Date: August 1985
Creator: Moses, Christopher K. (Christopher Karam)
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Size Fractionation of Metabolically Active Phytoplankton and Bacteria in Two Diverse Lentic Systems (open access)

Size Fractionation of Metabolically Active Phytoplankton and Bacteria in Two Diverse Lentic Systems

Simultaneous size fractionation of plankton populations associated with NaH^14CO_3 and ^3H-glucose uptake was employed in eutrophic Lake Texoma (Texas and Oklahoma) and oligotrophic Flathead Lake (Montana). Autoradiography was utilized to determine the role of specific microorganisms in community metabolism. Ultraplankton (0.45-10 μm) dominated plankton numbers and metabolic activity in both aquatic systems. Many of the most abundant species were not the most productive, in terms of inorganic C fixation. Rates of heterotrophic uptake of ^3H-glucose were small in comparison to photolithotrophic uptake in both lakes, Photoheterotrophy was more extensive in Flathead Lake, Autoradiographs indicated that bacteria were responsible for observed photoheterotrophy. Oscillatoria sp. exhibited. mixotrophy in Lake Texoma,
Date: August 1980
Creator: Ellis, Bonnie K.
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Nature-Guided Synthesis of Advanced Bio-Lubricants (open access)

Nature-Guided Synthesis of Advanced Bio-Lubricants

Article describes study which finds that Orychophragmus violaceus (Ov) seed oil has superior lubrication properties, based on the unusual structural features of the major lipid species—triacylglycerol (TAG) estolides.
Date: August 12, 2019
Creator: Romsdahl, Trevor; Shirani, Asghar; Minto, Robert E.; Zhang, Chunyu; Cahoon, Edgar B.; Chapman, Kent Dean et al.
Object Type: Article
System: The UNT Digital Library