Date of Award


Document Type


Degree Name

Master of Science (MS)


Biological Sciences



Committee Director

Lloyd Wolfinbarger, Jr.

Committee Member

Paul J. Homsher

Committee Member

Thomas O. Sitz

Call Number for Print

Special Collections LD4331.B46 M66


Neurospora produces a phase specific, cationic mucopolysaccharide composed primarily of galactosamine (GAG-MP) which becomes part of the cell wall and is later secreted into the media. Its appearance coincides with the onset of the restricted phase of growth and causes efflux of small molecular weight metabolites when incubated with conidial cells. This activity may be a product of electrostatic interactions of the GAG-MP with the conidial plasma membrane. The activity is blocked by acetylation of the primary amines on the molecule, digestion by enzymes that hydrolyze carbohydrate linkages and the inclusion of NaCl (lM) in the GAG-MP/conidia reaction mixture. The GAG-MP's physiological activity mimics that of known depolarizing agents. A model is proposed in which GAG-MP depolarizes the plasma membrane at the onset of the restricted phase of growth, stimulating a cell surface enzyme to produce endogenous cAMP which in turn switches on the enzymatic and genetic machinery necessary for that phase of growth.


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