Enzymology and Molecular Biology of Aflatoxin Biosynthesis.

Infections with mold pathogens have emerged as an increasing risk faced by patients under sustained immunosuppression. Species of the Aspergillus family account for most of these infections, and in particular Aspergillus fumigatus may be regarded as the most important airborne pathogenic fungus. The improvement in transplant medicine and the therapy of hematological malignancies is often complicated by the threat of invasive aspergillosis. Specific diagnostic methods are still limited as are the possibilities of therapeutic intervention, leading to the disappointing fact that invasive aspergillosis is still associated with a high mortality rate that ranges from 30% to 90%. In recent years considerable progress has been made in understanding the genetics of A. fumigatus, and molecular techniques for the manipulation of the fungus have been developed. Molecular genetics offers not only approaches for the detailed characterization of gene products that appear to be key components of the infection process but also selection strategies that combine classical genetics and molecular biology to identify virulence determinants of A. fumigatus. Moreover, these methods have a major impact on the development of novel strategies leading to the identification of antimycotic drugs. This review summarizes the current knowledge on the biology, molecular genetics, and genomics of A. fumigatus.

Menacing mold: the molecular biology of Aspergillus fumigatus.

Efficient protoplast isolation from fungi using commercial enzymes

SUMMARY Forced interspecific hybridization has been used in yeasts for many years to study speciation or to construct artificial strains with novel fermentative and metabolic properties. Recent genome analyses indicate that natural hybrids are also generated spontaneously between yeasts belonging to distinct species, creating lineages with novel phenotypes, varied genetic stability, or altered virulence in the case of pathogens. Large segmental introgressions from evolutionarily distant species are also visible in some yeast genomes, suggesting that interspecific genetic exchanges occur during evolution. The origin of this phenomenon remains unclear, but it is likely based on weak prezygotic barriers, limited Dobzhansky-Muller (DM) incompatibilities, and rapid clonal expansions. Newly formed interspecies hybrids suffer rapid changes in the genetic contribution of each parent, including chromosome loss or aneuploidy, translocations, and loss of heterozygosity, that, except in a few recently studied cases, remain to be characterized more precisely at the genomic level by use of modern technologies. We review here known cases of natural or artificially formed interspecies hybrids between yeasts and discuss their potential importance in terms of genome evolution. Problems of meiotic fertility, ploidy constraint, gene and gene product compatibility, and nucleomitochondrial interactions are discussed and placed in the context of other known mechanisms of yeast genome evolution as a model for eukaryotes.

Evolutionary Role of Interspecies Hybridization and Genetic Exchanges in Yeasts

Filamentous fungi are important in medicine, industry, agriculture, and basic biological research. For example, some fungal species are pathogenic to humans, whereas others produce beta-lactam antibiotics (penicillin and cephalosporin). Industrial strains produce large amounts of enzymes, such as glucoamylase and proteases, and low molecular weight compounds, such as citric acid. The largest and most economically important group of plant pathogens are fungi. Several fungal species have biological properties and genetic systems that make them ideally suited for basic biological research. Recently developed techniques for genetic engineering of filamentous fungi make it possible to alter their detrimental and beneficial activities in novel ways.

https://science.sciencemag.org/content/sci/244/4910/1313.full.pdf

Genetic Engineering of Filamentous Fungi

INTRODUCTION 21 ISOLATION OF PROTOPLASTS AND THEIR P ROPERTIES 22 Enzymatic Methods for Protoplast Isolation 22 Nonenzymatic Procedures for Protoplast Release 26 Properties of Protopiasts 27 WALL REGENERATION AND REVERSION OF PROTOPLASTS 28 Frequency of Protoplast Reversion 28 Morphology of Protoplast Reversion 29 Ultrastructure and Composition of the Regenerated Wall ..... 30 Biochemical Aspects oj Wall Biogenesis 31 PROTOPLAST FUSION AND GENETIC MANIPULATION 33 Protoplast Fusion and the Hybridization of Fungal Species 33 Transformation in Fungi by Using Protoplasts . .. ........ 36 CONCLUDING REMARKS 36

J F Peberdy

Papers

Fungal protoplasts: isolation, reversion, and fusion