ABSTRACT
Research efforts in the past three decades have revealed the complex mechanisms employed by fungi to control gene activity. In their natural habitat, fungi are capable of using a variety of compounds as nitrogen and/or carbon sources. However, not all nitrogen and/or carbon sources support growth and development equally. This chapter will focus primarily on the regulatory mechanisms governing nitrogen and carbon metabolism, particularly on utilization of alternative nitrogen and carbon sources, in the model filamentous fungi Aspergillus nidulans and Neurospora crassa. Recent progress in the characterization of global factors affecting nitrogen and carbon metabolism, and pathway-specific metabolic gene regulation will be emphasized. Global regulators act on a wide range of unrelated activities involved in utilization of an array of different compounds, whereas pathway-specific regulators usually act specifically within a single or several related pathways to mediate coordinated expression of activities required for utilization of related compounds. A number of authoritative reviews of early aspects of regulation of nitrogen and carbon metabolism have been published (Caddick et al. 1994; Ebbole 1998; Kelly 1994; Felenbok and Kelly 1996; Marzluf 1997; Ruijter and Visser 1997; Scazzocchio et al. 1995).
