Identifying differentially expressed genes in the dimorphic fungusPenicillium marneffeiby suppression subtractive hybridization

Abstract

Penicillium marneffei is the only known Penicillium species that exhibits temperature-dependent dimorphic growth. It usually infects immunocompromised individuals and may cause fatal penicilliosis marneffei. Its pathogenicity appears to be intimately related to the dimorphic transition from a mycelial phase in the environment to a yeast phase in the human host. To further understand the molecular mechanisms in the switching process of Penicillium marneffei, differential gene expression analysis was carried out between the mycelial phase and the yeast phase by suppression subtractive hybridization. Five hundred genes from forward and reverse-subtracted cDNA libraries were screened by cDNA array dot blotting and 43 genes were identified to be differentially expressed. These genes were found to be homologs of genes involved in various cellular processes including cell wall synthesis, signal transduction, cell cycle, substance transport, general metabolism and stress response, etc. Six genes were further analyzed using relative quantification real-time reverse transcriptase PCR. It is believed that these genes determine some of the major characteristics of dimorphism in Penicillium marneffei.