9407810 Stringer This project is being funded as a Research Planning Grant. The work centers on Pneumocystis, an exotic fungus which was for many years thought to be a protozoan, and which may represent a new order of fungi. The organism exists in morphologically distinct developmental forms, cysts and trophic forms, and very little is known about its life cycle. The project will address a single fundamental and important question: can genetic markers be identified which are specific to the different forms of Pneumocystis? The specific aims are to separate the cysts and trophic forms of Pneumocystis from natural isolates, prepare mRNA from the different forms, compare them by a PCR-based technique called differential display to identify cDNAs that appear to be differentially expressed in the different forms, use standard analytical techniques to verify that the mRNAs detected by differential display are present in different amounts in the different forms, and determine the sequences of these differential cDNAs. In addition, in situ hybridization will be used to define expression of the mRNAs in the various forms of the organism. %%% Pneumocystis is an unusual fungal pathogen that is commonly found in mammalian lungs and which causes pneumonia in immuno-compromised mammalian hosts. It is difficult to study because to date it has not been cultured successfully in vitro. Taxonomically, it appears to be only distantly related to other known fungi, and in fact for many years was mistakenly believed to be a protozoan. Because of the novel taxonomic status of this organism, the significance of studies of it extend well beyond merely learning more about an important pathogen. Molecular research on Pneumocystis and organisms like it has only recently begun. The proposed work will be an important contribution to the evolutionary and general biological understanding of fungi in general. ***
