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Studies on the Morphology and Biology of Cotton Rats (Sigmodon hispidus) from Northern Mexico to Southern Nebraska

Description: This investigation was designed to evaluate the need for retaining both Sigmodon hispidus texianus and Sigmodon hispidus berlandieri as subspecific designations. An attempt was made to demonstrate bioclimatic variation and reproductive seasonality in cotton rats. The validity of applying the results of isolated studies of cotton rat populations to the species as a whole was examined.
Date: December 1971
Creator: Cleveland, Arthur Gordon
Partner: UNT Libraries

Heat Resistance in Vegetative Cells and Cysts of Azotobacter

Description: The purpose of the current study is to determine something of the nature of the heat resistance in Azotobacter, if in fact this is found to exist. An attempt is made to determine the specific physiological state associated with heat resistance as well as to resolve this resistance quantitatively.
Date: August 1969
Creator: Rosenthal, Raoul S.
Partner: UNT Libraries

Pleomorphism in Selected Genera of Algae

Description: It is the purpose of this study to ascertain what environmental factors might cause morphological changes exhibited by certain algae, also to determine if this variation in morphology is vegetative, reproductive, or artifactual in nature, and to show what effects these changes in morpohology might have on classification of the organisms in question.
Date: June 1967
Creator: Bruton, Barbara A.
Partner: UNT Libraries

Some Effects of X-Irradiaion on the Adrenal Response to Hypothalamic Stimulation in Rats

Description: Exactly where in the hypothalamus is the adrenal-pituitary response to X-irradiation "triggered" or initiated? Moreover, does ionizing radiation act directly on specific centers in the brain or does it act indirectly via the production of some humoral agents? Finally, what role does the hypothalamus play in the radiation-syndrome? The purpose of the present study was to attempt to answer these questions by determining the effects of two stressor agents, X-irradiation and electrical stimulation applied either singly or together, on the activity of the adrenal-pituitary axis. The parameters measured were changes in plasma corticosterone, in circulating eosinopihils, and in adrenal gland weight.
Date: January 1967
Creator: Agnew, Robert Laing
Partner: UNT Libraries

A Screening of Fungi for Metabolites Inhibitory to the Growth of Bloom-Forming Blue-Green Algae

Description: Since many approaches to dealing with algal blooms are inefficient, expensive, or harmful, it was concluded that a biologically-synthesized chemical agent, specifically inhibitory to pre-bloom algal cells, might prove helpful in controlling algal blooms. Fungi were chosen as the biological entities to investigate for such a chemical.
Date: December 1970
Creator: Hardcastle, Ronald V.
Partner: UNT Libraries

The Autecology of Celtis Laevigata in Flood Plain Forests of Denton County, Texas

Description: This thesis describes the present nature of one facet of some of the flood plain forest stands in Denton County, Texas. The specific purpose was to demonstrate the presence or absence of difference between the Celtis laevigata (commonly known as the hackberry, southern hackberry or sugarberry) populations in stands on Denton Creek and Elm Fork of the Trinity River.
Date: January 1970
Creator: Hander, Lecil B.
Partner: UNT Libraries

A Study of Malate Dehydrogenase Isoenzymes in the Midge Larva Glyptotendipes barbipes

Description: Two isoenzymes of malate dehydrogenase were isolated and partially purified from the midge larva Glyptotendipes barbipes. Differential centrifugation followed by cellulose acetate and polyacrylamide gel electrophoresis revealed one isoenzyme associated with the mitochondrial fraction and another form found only in the cytoplasm.
Date: May 1972
Creator: Jones, Vicki E.
Partner: UNT Libraries

Some Acute Effects of X-Irradiation (LD100) on Plasma and Adrenal Tissue Histamine in Rats

Description: The effects of a lethal dose (1380 r) of X-irradiation on plasma and adrenal tissue histamine levels of rats were studied. The plasma histamine response was triphasic (increase at 1-3 hours, decrease at 5 and 9 hours and return to control at 24 hours post-irradiation). The adrenal tissue histamine response was found to be biphasic (decrease at 1 to 9 hours and a return to control level at 24 hours post-irradiation).
Date: May 1972
Creator: Ferguson, James L.
Partner: UNT Libraries

Actinoplanes Philippinensis: Effect of Carbon Sources on Zoospore Production

Description: Actinomycetes are able to utilize a great variety of carbohydrates, like sugar. The particular kind of sugar and its concentration has decisive effect on the growth of microorganisms. The proper nutritional media aids also in the production of spores. Based on this generalization, that the growth and sporulation of microorganisms are greatly influenced by the nature and the concentration of carbohydrates, an attempt has been made to study Actinoplanes philippinensis with respect to this influence.
Date: May 1968
Creator: White, Olivia
Partner: UNT Libraries

Factors Affecting Slime Formation in a Spray Irrigation Waste Disposal System

Description: It was the purpose of this investigation to determine (1) what organisms are associated with the formation of this slime layer, (2) if certain chemical factors in the environment either enhance or retard formation of the slime layer, (3) whether or not there are certain chemical factors which are detrimental to slime formation, yet not detrimental to purification, or that perhaps enhance purification, (4) whether or not there are chemical factors which enhance purification of the effluent without preventing slime formation, and (5) what effects the chemical treatments have on the microbial flora of the soil system.
Date: August 1970
Creator: Jorgensen, James H.
Partner: UNT Libraries

A Study of a Branchiobdellid from Denton County, Texas

Description: In this study, branchiobdellids were collected from crayfish captured from two adjacent sites in Denton County, Texas. Identification of the branchiobdellid, Cambarincola vitrea Ellis, was first made and then work was extended to include several topics of ecological interest.
Date: May 1970
Creator: Koepp, Stephen J.
Partner: UNT Libraries

Nitrogen Accretion on a Lacustrine Plain

Description: The purpose of the investigation was to locate the plant population which had the greatest impact on soil nitrogen in a successional sequence from newly deposited alluvia to a mature streamside forest, and to evaluate the pioneer populations in terms of their annual nitrogen contribution.
Date: May 1972
Creator: Davis, Karla S.
Partner: UNT Libraries

Obligately Thermophilic Nitrogen-Fixation in Some Soil Bacteria

Description: In the work presented here, it is claimed that bacteria have been isolated which are capable of growth at high temperatures utilizing molecular nitrogen as their sole nitrogen source. Soil bacteria were isolated which grew at 55 C in nitrogen-free media. They were found to be obligatory thermophiles in nitrogen-free media and facultative thermophiles in media containing organically bound nitrogen.
Date: August 1971
Creator: Milam, Mary
Partner: UNT Libraries

Effects of High Altitude Exposure on Capillary Permeability

Description: Observations of decreases in plasma volume, shifts in plasma and lymph protein concentrations, and increases in capillary permeability at high altitude have been reported in the literature by several investigators. This investigation was begun in an attempt to elucidate the possible significance of these phenomena in future space exploration, and because of the lack of knowledge concerning the underlying mechanisms. The purpose of this investigation was to determine the effects of exposure to hypobaric pressures on the capillary permeability to the normal plasma and lymph proteins.
Date: December 1971
Creator: Reaves, Troy Albert
Partner: UNT Libraries