Quantitative analysis of gene expression in sexual structures ofAspergillus nidulansby sequencing of 3′-directed cDNA clones

Abstract

We constructed a 3'-directed cDNA library of cleistothecia and Hülle cells of Aspergillus nidulans to examine gene expression patterns of the sexual structures and to have probes necessary to isolate sexual structure-specific genes. Sequencing of 360 randomly selected cDNA clones yielded 272 expressed sequence tags (ESTs), most of which probably represent frequently or less expressed genes in sexual structures of A. nidulans. Among the 272 ESTs, 33 ESTs (87 cDNA clones) appeared more than once and 2 ESTs appeared 6 times; 9 ESTs matched GenBank entries. When compared with sequences obtained from a mycelial 3'-directed cDNA library of A. nidulans, 28 out of 33 ESTs seem to be sexual structure-specific. Northern blot analyses of 20 ESTs showed that 17 are sexual structure-specific. The remaining three ESTs also hybridized with RNA isolated from vegetative mycelia. These results suggest that analyses of ESTs from different cell types or tissues can readily demonstrate gene expression patterns of specific cell types and identify cell type-specific cDNA probes.

Fungal Morphogenesis, from the Polarized Growth of Hyphae to Complex Reproduction and Infection Structures

“…Early on, both N. crassa and S. macrospora were used for differential gene expression studies, using expressed sequence tag (EST) sequencing or differential hybridization techniques to discover fruiting body-specific genes (338,339). Since the isolation of ascomycete fruiting bodies is difficult due to their small size (Ͻ500 m), in these studies, RNA was isolated not only from fruiting bodies but also from nonreproductive hyphae.…”