Effects of Congo red on wall synthesis and morphogenesis in Saccharomyces cerevisiae

Congo red, a stain which prevents polyglycan microfibril assembly, was assayed on growing cells of Saccharomyces cerevisiae. In the presence of 0.25 mg/ml of the chemical, yeast developed aberrant wall thickenings and malformed septa, and underwent several budding events without the occurrence of the separation between mother and daughter cells. It is suggested that Congo red may uncouple polymerization and crystallization of the wall constituents, primarily chitin, that normally form microfibrils. It is also propsed that the regular assembly of the chains into microfibrils is needed to give a correct rate and direction to the process of polyglycan synthesis.