Asexual Spore Release from Saprolegniaceous Water Moulds: Involvement of Calmodulin

Abstract

SUMMARY: The localized cell wall lysis associated with asexual spore release from sporangia and spore cysts of saprolegniaceous water moulds appears, based on immunocytochemical and inhibitor studies, to be dependent on calmodulin (CaM). Distinct bands of CaM surround the exit pores of sporangia and cysts produced by Achlya ambisexualis, Dictyuchus monosporus and Saprolegnia ferax. In differentiating sporangia and cysts, CaM becomes concentrated in the apical papillae, at the tips of which exit pores are formed. While all stages of sporulation can be inhibited to an extent by micromolar concentrations of trifluoperazine, an anti-CaM drug, spore release is the most sensitive.