Lessons from the genome sequence of Neurospora crassa: tracing the path from genomic blueprint to multicellular organism.

We present an analysis of over 1,100 of the approximately 10,000 predicted proteins encoded by the genome sequence of the filamentous fungus Neurospora crassa. Seven major areas of Neurospora genomics and biology are covered. First, the basic features of the genome, including the automated assembly, gene calls, and global gene analyses are summarized. The second section covers components of the centromere and kinetochore complexes, chromatin assembly and modification, and transcription and translation initiation factors. The third area discusses genome defense mechanisms, including repeat induced point mutation, quelling and meiotic silencing, and DNA repair and recombination. In the fourth section, topics relevant to metabolism and transport include extracellular digestion; membrane transporters; aspects of carbon, sulfur, nitrogen, and lipid metabolism; the mitochondrion and energy metabolism; the proteasome; and protein glycosylation, secretion, and endocytosis. Environmental sensing is the focus of the fifth section with a treatment of two-component systems; GTP-binding proteins; mitogen-activated protein, p21-activated, and germinal center kinases; calcium signaling; protein phosphatases; photobiology; circadian rhythms; and heat shock and stress responses. The sixth area of analysis is growth and development; it encompasses cell wall synthesis, proteins important for hyphal polarity, cytoskeletal components, the cyclin/cyclin-dependent kinase machinery, macroconidiation, meiosis, and the sexual cycle. The seventh section covers topics relevant to animal and plant pathogenesis and human disease. The results demonstrate that a large proportion of Neurospora genes do not have homologues in the yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe. The group of unshared genes includes potential new targets for antifungals as well as loci implicated in human and plant physiology and disease.

Changes in fatty acid composition of Neurospora crassa accompany sexual development and ascospore germination.

Fatty acid composition was determined during several stages of sexual development in Neurospora crassa. Triacylglycerol was the predominant acyl lipid in cultures undergoing sexual development. The absolute amounts of triacylglycerol in fertilized cultures varied over time, in contrast to control (unfertilized or mock-fertilized) cultures, in which the amount of triacylglycerol decreased linearly with age. In cultures competent to undergo sexual development, alpha-linoleate was the predominant fatty acid, ranging from 53 to 65% of the total fatty acid mass. alpha-Linolenate was 3% or less of the total fatty acid, in marked contrast to the much higher levels (10-35%) typically reported for vegetative cultures. In fertilized cultures, a slightly higher mass ratio of oleate was also observed. This difference was due to the developing asci: in developing asci and mature ascospores, oleate replaced alpha-linoleate as the predominant fatty acid (45 to 50% of the total). In germinating ascospores, the fatty acid composition approached that of vegetative cultures 6 h after inducing germination by heat activation. These results show that the fatty acid composition of sexual tissues of Neurospora differs substantially from the composition of asexual tissues, and that extensive changes in fatty acid composition correlate with several events in the sexual stage of development.