Degree Discipline

4 Matching Results

Results open in a new window/tab.

Intracellular Location of Carotenoid Pigments in Yeast-Phase Cells of Wangiella Dermatitidis and Cell Wall Morphology After Enzyme Treatment (open access)

Intracellular Location of Carotenoid Pigments in Yeast-Phase Cells of Wangiella Dermatitidis and Cell Wall Morphology After Enzyme Treatment

Carotenoid pigments in W. dermatitidis, the first pathogenic, dematiaceous fungus in which carotenoid pigments nave been reported, are located primarily (81%) in lipid organelles which floated on the surface of the supernatant fraction of lysed cells. Pigment in this fraction could be extracted with ethyl ether without prior treatment with acetone indicating the pigment is unbound in the lipid organelle. Eight percent remains after exhaustive ether extraction and is recovered after the sample is treated with acetone indicating this fraction is non-covalently bound to proteins in the membranes associated with the lipid organelle. The remaining pigment (about 12%) represents contamination of the supernatant with the lipid organelles.
Date: December 1991
Creator: Foster, Linda Ann
System: The UNT Digital Library
Comparative Biochemistry and Evolution of Aspartate Transcarbamoylase from Diverse Bacteria (open access)

Comparative Biochemistry and Evolution of Aspartate Transcarbamoylase from Diverse Bacteria

Aspartate transcarbamoylase (ATCase) catalyzes the first committed step in pyrimidine biosynthesis. Bacterial ATCases are divided into three classes, A, B and C. Class A ATCases are largest at 450-500, are. dodecamers and represented by Pseudomonas ATCase. The overlapping pyrBC' genes encode the Pseudomonases ATCase, which is active only as a 480 kDa dodecamer and requires an inactive pyrC'-encoded DHOase for ATCase activity. ATCase has been studied in two non-pathogenic members of Mycobacterium, M. smegmatis and M. phlei. Their ATCases are dodecamers of molecular weight 480 kDa, composed of six PyrB and six PyrC polypeptides. Unlike the Pseudomonas ATCase, the PyrC polypeptide in these mycobacteria encodes an active DHOase. Moreover, the ATCase: DHOase complex in M. smegmatis is active both as the native 480 kDa and as a 390 kDa complex. The latter lacks two PyrC polypeptides yet retains ATCase activity. The ATCase from M. phlei is similar, except that it is active as the native 480 kDa form but also as 450,410 and 380 kDa forms. These complexes lack one, two, and three PyrC polypeptides, respectively. By contrast,.ATCases from pathogenic mycobacteria are active only at 480 kDa. Mycobacterial ATCases contain active DHOases and accordingly. are placed in class A1 . …
Date: May 1999
Creator: Hooshdaran, Massoumeh Ziba
System: The UNT Digital Library
Biodegradation of Certain Petroleum Product Contaminants in Soil and Water By Selected Bacteria (open access)

Biodegradation of Certain Petroleum Product Contaminants in Soil and Water By Selected Bacteria

Soil contamination by gasoline underground storage tanks is a critical environmental problem. The results herein show that in situ bioremediation using indigenous soil microorganisms is the method of choice. Five sites were selected for bioremediation based on the levels of benzene, toluene, ethylbenzene and xylene and the amount of total petroleum hydrocarbons in the soil. Bacteria capable of degrading these contaminants were selected from the contaminated sites and grown in 1,200 I mass cultures. These were added to the soil together with nutrients, water and air via PVC pipes.
Date: December 1995
Creator: Nevárez-Moorillón, Guadalupe Virginia
System: The UNT Digital Library
Scientific Considerations of Olestra as a Fat Substitute (open access)

Scientific Considerations of Olestra as a Fat Substitute

Olestra is, a sucrose polyester, a noncaloric fat substitute, made from sucrose and several fatty acid esters. It has been approved by the FDA as a food additive used in preparing low-fat deep-frying foods such as savory snacks. Available literature on olestra was evaluated that had both positive and negative connotations. Clinical trials in numerous species of animals including humans were conducted to determine if olestra would affect the utilization and absorption of macro- and micronutrients; the effects of olestra on growth, reproduction, or its toxicity were also examined. The roles of olestra as a fat substitute, how it could effect on humans and the environment, and the potential impacts from its use in large amounts were assessed. Olestra can be removed from the environment by aerobic bacteria and fungi which may be isolated from activated sludge and soils.
Date: December 1999
Creator: Rattagool, Kullakan
System: The UNT Digital Library