Mucopolysaccharide Which Regulates Growth in Neurospora

Abstract

Neurospora produces a mucopolysaccharide (called MP) which inhibits its growth, causes vacuolation and agglutination of its cells, and precipitates its purified membrane protein. Cultures of a colonial strain display a phase of slow growth; the induction of this phase is traced to the production of MP by the mold. Stationary-phase cultures of wild type also produce MP. MP is a polymer of galactosamine, its amino groups only partially acetylated, probably containing other minor components. MP molecular weight is approximately 10 6 . Complete acetylation abolishes the biological activities of MP. It is suggested that the regulatory effect of MP is mediated by its interaction with the protoplasmic membrane.