Identification of three genes expressed primarily during development in Physarum polycephalum

During the life cycle of Physarum polycephalum, uninucleate amoebae develop into multinucleate syncytial plasmodia. These two cell types differ greatl y in cellular organisation, behaviour and gene expression. Classical geneti c analysis has identified the mating-type gene, matA, as the key gene contr olling the initiation of plasmodium development, but nothing is known about the molecular events controlled bu matA. In order to identify plasmodium d evelopment, but nothing is known about the molecular events controlled by m atA. In order to identify genes involved in regulating plasmodium formation , we constructed a subtracted cDNA library from cells undergoing developmen t. Three,genes that have their highest levels of expression during plasmodi um development were regulated in development) and identified: redA, redB (r egulated in development) and mynD (myosin). Both redA and redB are single-c opy genes and are not members of gene families. Although redA has no signif icant sequence similarities to known genes, redB has sequence similarity to invertebrate sarcoplasmic calcium-binding, proteins. The mynD gene is clos ely related to type II myosin heavy-chain genes from many organ isms and is one of a family of type II myosin genes in P. polycephalum. Our results in dicate that many more ren genes remain to be identified, some of which may play key roles in controlling plasmodium formation.