|Ibrahim, Ashraf - UCLA-MEDICAL CENTER|
Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: January 15, 2006
Publication Date: April 15, 2006
Citation: Ibrahim, A.S., Skory, C.D. 2006. Genetic manipulation of zygomycetes. In: Kavanagh, K. editor. Medical Mycology, Cellular and Molecular Techniques. New York, NY: John Wiley & Sons. p. 305-325. Technical Abstract: During the last decade, advances in molecular biology have greatly advanced our understanding of the pathogenesis of invasive fungal infections, especially candidiasis and cryptococcosis, and most recently aspergillosis and blastomycosis. These advances were greatly facilitated by molecular genetic studies of these pathogens. However, the few published studies of the pathogenesis of mucormycosis have emphasized host defense mechanisms without attempting to investigate specific virulence factors of the causative organism. The limited availability of genetic tools for the study of the Mucorales fungi is a major contributing factor to the paucity of studies on the organism’s pathogenesis. While several laboratories have described numerous genetic studies with R. oryzae, R. delemar, R. niveus, M. circinelloides, A. glauca, Phycomyces blakesleeanus, and Rhizomucor pussilis certain basic molecular biology procedures, such as stable transformation and double cross-over gene replacements still are problematic. Difficulties with genetic modification of the Mucorales are partly due to the unique ability of these fungi to replicate the DNA used for transformation autonomously in a concatenated high molecular weight form. These transformants tend to lose the transformed plasmid(s) when cultured on non-selection media, resulting in a very low mitotic stability. Nevertheless, significant progress and understanding of the genetic mechanisms of the Mucorales continues at an ever increasing pace. An overview of these methods and techniques, with particular emphasis on R. oryzae, is presented in this chapter.