The elongation of palmitic acid in cell-free extracts of Penicillium chrysogenum

No Thumbnail Available
Ashley, Jill K.
Bennett, Alice S.
Issue Date
Thesis (M.S.)
Other Identifiers

Results of previous research on whole-cell cultures of Penicillium chrysogenum have suggested that acetyl CoA, without being converted to malonyl CoA, supplies the two carbon units for the elongation of palmitic acid. The purpose of this study was to determine the mode of elongation of 1-t4C palmityl CoA by a 20,000 x g mitochondrial pellet from P. chrysogenum.Acetyl CoA or malonyl CoA was incubated with radioactivelylabeled palmityl CoA for 20 minutes. Avidin was added to some experimental reaction mixtures. The resulting fatty acids were saponified, extracted with hexane, methylated with diazomethane, and purified by thin layer chromatography. The methyl esters were separated and identified by gas-liquid chromatography. The radioactivity of each methyl ester was determined by liquid scintillation spectrometry.Elongation of palmityl CoA was observed in the presence of acetyl CoA, but not in the presence of malonyl CoA. The addition avidin produced a greater proportion of short-chained fatty acidsthe expense of palmitic acid, but did not decrease the percentage of long-chained fatty acids produced.A high proportion of label was recovered in the C18:3 fatty acid, linolenic acid. This suggested that two pathways of linolenic acid synthesis may be operating in this organism.Methods for detection and control of cancer encompass a large area of today's research. Recent use of granulomas as a model for such detection and control may be a promising field, especially for monitoring tumor antigens and immune responses. These granuloma systems are increasingly becoming vehicles in the study of tumor immunology. Although granulomas may be induced naturally by means of foreign bodies i.e. viral, fungal, or bacterial agents, new methods are being established to produce artificial granuloma systems. These systems include chemical or foreign body implantations followed by tumor vaccine challenges. The research presented here involved the use of a golf ball-induced granuloma for the purpose of establishment of a detection system for immune responses. The use of a golf ball-induced granuloma provided a closed system for monitoring cell-mediated and humoral responses to tumor antigens. Immune responses were monitored by means of hematocrits (packed blood cell counts), white blood cell differential counts, and electrophoretic results.Hematocrit results indicated no great immune response to the closed vaccine injected granulomasystems. Observations made on differential white blood cell counts indicated decreasing neutrophil/lymphocyte ratios for cellular immune responses. Electrophoretic results for granuloma fluids indicated decreases in albumin levels concurrent with increases in peak two,and complete loss of peak three following vaccination. Responses to tumor specific antigens in the form of cell-mediated immune responses are indicated by the results presented in this research. Utilization of the golf ball-induced granuloma system provided a means of separating the cell-mediated and humoral immune responses.Tumor specific antigens elicited various immune responses and provide hope for future identification of tumors by this method. Future development and utilization of the golf ball-induced granuloma system may be potential means of monitoring cell-mediated immune responses to tumor malignancies.