ABSTRACT
CONTENTS 20.1 Introduction ............................................................................................................................. 343
20.1.1 TE Detection ............................................................................................................. 344 20.2 Spectrum of Transposable Elements in the Three Species .................................................... 345
20.2.1 TEs in Aspergillus nidulans ..................................................................................... 345 20.2.2 TEs in Aspergillus fumigatus ................................................................................... 347 20.2.3 TEs in Aspergillus oryzae ........................................................................................ 347
20.3 Repeat-Induced Point Mutation .............................................................................................. 347 20.4 A+T Content ............................................................................................................................ 348 20.5 Clustering and Fragmentation ................................................................................................ 349
20.5.1 Aspergillus fumigatus ............................................................................................... 349 20.5.2 Aspergillus nidulans ................................................................................................. 351 20.5.3 Aspergillus oryzae .................................................................................................... 351
20.6 Transposon-Related Genes in Aspergillus nidulans ............................................................... 351 20.7 Transcription from TEs and Transposition ............................................................................. 352 20.8 Implications for Genome Expansion, Sexuality, and Chromosomal Rearrangement ............ 352
20.8.1 Genome Expansion ................................................................................................... 352 20.8.2 Sexuality ................................................................................................................... 352 20.8.3 Chromosomal Rearrangement .................................................................................. 353
20.9 Conclusions ............................................................................................................................. 353 Acknowledgment ............................................................................................................................... 354 References .......................................................................................................................................... 354
20.1 Introduction The release of genome sequences for three Aspergillus species provides an opportunity to examine transposable elements (TEs-–here used interchangeably with “transposons” and “retrotransposons”) in three related organisms, treating these genomes as historical records of successive waves of TE proliferation and subsequent decay. Only a small proportion of these relatively compact genomes are made up of TEs, but despite this, all three include a wide spectrum of TE types. There is strong evidence, in all three fungi, of a destructive process specifi c for repeated sequences, namely repeat-induced point mutation (RIP), now widely reported in fi lamentous ascomycetes.
