Expression Profile of flbD During Morphogenesis in the Dimorphic Fungus Penicillium Marneffei

Abstract

Penicillium marneffei is a pathogenic fungus that is thermally dimorphic in nature. It is able to exist as mold at 25°C and as yeast at 37°C. With the emergence of the AIDS epidemic, the number of infections due to this fungus also grew. Penicilliosis due to P. marneffei is considered to be an AIDS defining illness. The genes that may regulate the processes of conidiation and dimorphism in P. marneffei need to be examined in detail. One such gene is flbD, belonging to the family of flb genes. flbD is thought to regulate conidiation in P. marneffei. This particular study attempts to characterize a mutant (I242) generated by Agrobacterium-mediated transformation (AMT). This mutant is able to form conidia at 37°C, compared to the wild type which grows as a yeast. We hypothesize that flbD over expression is in this mutant is responsible for this aberrant phenotype. RNA was extracted from the wild type F4 strain of P. marneffei and the mutant I242 at 24 hours and 120 hours of growth (mold and yeast phases) in broth cultures. RNA from the conidia of both the strains was also collected. cDNA was synthesized from these samples. RT-PCR was conducted on the cDNA samples in an attempt to determine the expression profile of flbD in the wild type and mutant. The results show that, under conditions that do not favor conidiogenesis (growth in broth), flbD is expressed by strain I242, but not the wild type. This observation supports our hypothesis.