Résumé
This chapter mainly focuses on specific genes of Aspergillus fumigatus as well as genes missing in A. fumigatus but present in other Aspergillus species, with the aim to identify genes that encode particular functions specifically associated with the life-style of A. fumigatus. Species-specific comparisons shown in the chapter were based on the BLASTP program, with the pam250 substitution matrix to favor recognition of large similar segment pairs and the seg filter to mask compositionally biased regions in the query sequences. In each considered species, each nonunique protein is assigned to a class of paralogs. Clustering of genes responsible for secondary metabolite synthesis have been already identified in A. fumigatus. The survey of the genome led to the identification of a cluster of genes that seems specific to A. fumigatus. Among the 377 genes specific to A. fumigatus, 74% encode small proteins (shorter than 150 amino acids), whereas only 8% of the genes in the whole A. fumigatus genome encode such small proteins. Genome comparison studies in Aspergillus have shown that species- or genus-specific genes constitute a tiny part of the genome compared to other fungal species. Moreover, the analyses of A. fumigatus-specific genes have not been very informative in terms of gene functions and do not highlight any particular pathway which could be unique to this fungus. The chapter confirms that the eight analyzed Aspergillus species are closely related and shows that no major particular event of function loss or gain took place in A. fumigatus during its evolution.