Implications of some genetic control mechanisms in Neurospora.

Abstract

INEODUCTION Apologia For the would-be writer of a review article, it can be sobering to ask whether the article is needed. On posing this question to myself, I realized that a number of very perceptive and, in some cases, extensive reviews have already appeared in print. These are listed below. I saw few ways to cover the same ground differently, and certainly no way to cover it better. It seemed more profitable to use this space as an opportunity (i) to examine a few of the special features of Neurospora crassa and closely related species that are likely to escape attention elsewhere and (ii) for some unabashed speculation about the evolutionary pressures that have shaped the control mechanisms extant in Neurospora and perhaps in other eucaryotes. This article is meant to be read with that in mind. Books, Reviews, and Other Sources of Information The following sources will be useful to those wishing to get abreast of the literature of Neurospora. Fincham and Day (45). General fungal genetics textbook, with emphasis on Neurospora. Chromosome mechanics, mutagenesis, mapping functions, fine structure determination, extrachromosomal inheritance, physiological genetics. Davis (37). A critical review of metabolic organization and compartmentation of function in Neurospora and other fungi. Prevention of futile cycling by summation of anabolism and catabolism. Marzluf (89). A valuable discussion of genetic regulation of metabolic pathways in fungi. Perkins and Barry (103). A remarkable, comprehensive review of cytogenetics, meiosis and mitosis, and chromosomal aberrations; life cycle of N. crassa and related heterothallic and pseudohomothallic species. Contains genetic maps and tabulations of kinds of auxotrophs and morphological, color, and other kinds of mutants. Perkins et al. (105). Natural history of the genus Neurospora. Taxonomy and chromosome homology of a large collection of isolates from nature. Srb et a1. (121). Genetics of development of the sexual apparatus. Nelson et al. (98). Biochemical and morphological changes during conidium formation, especially as revealed by mutational dissection. Schmit and Brody (116). Biochemistry and physiology of conidial germination. Brody (20) and Scott (117). Effect of enzyme levels and metabolic pools on cell wall and membrane composition and on morphology. Mishra (95). Various aspects of morphogenesis. Bachmann and Strickland (12). An inval-361

Identification of genes displaying differential expression in the nuc-2 mutant strain of the mold Neurospora crassa grown under phosphate starvation

“…Therefore, the differential expression of these transcripts that occurs in the nuc-2A mutant or in the wild-type strains of N. crassa, respectively, grown in low-or high-Pi medium (Fig. 2) could account for the regulation of the Pi-repressible phosphatases (Metzenberg, 1979). In fact, these ESTs were expressed when the nuc-2 gene is nonfunctional, as it occurs in this gene when the wild-type strain is grown in sufficient Pi (Fig.…”

“…All living organisms have evolved complex signal transduction networks that enable them to sense the availability of nutrients and modulate metabolic activities for their acquisition. The filamentous mold Neurospora crassa synthesizes a number of Pi-repressible phosphatases and permeases that have the function of making more Pi available to the cell, i.e., these enzymes are synthesized and secreted in response to the signaling of phosphorus starvation (Metzenberg, 1979;Han & Rossi, 1989). The genetic and molecular mechanisms controlling this response in N. crassa include four regulatory genes, nuc-2, preg, pgov, and nuc-1, involved in a hierarchical relationship (Metzenberg, 1979).…”

“…The filamentous mold Neurospora crassa synthesizes a number of Pi-repressible phosphatases and permeases that have the function of making more Pi available to the cell, i.e., these enzymes are synthesized and secreted in response to the signaling of phosphorus starvation (Metzenberg, 1979;Han & Rossi, 1989). The genetic and molecular mechanisms controlling this response in N. crassa include four regulatory genes, nuc-2, preg, pgov, and nuc-1, involved in a hierarchical relationship (Metzenberg, 1979). The availability of Pi is sensed by the nuc-2 gene, whose transcription is regulated in response to the levels of Pi (Peleg et al, 1996a).…”

The role of structural and regulatory genes in the development of maize endosperm

“…This situation is reminiscent of some of the regulatory models proposed in other eukaryotic systems, where a cascade of events leading to structural gene activation is ascribable to multiple regulatory genes. Some examples of this are the control of globin synthesis in the reticulocyte [221], the regulation of phosphate absorption in Neurospora [222] and the ga14-guZ80 interaction regulating the galactose pathway in Saccharomyces [223]. Each case shows some similarities with the hypothesis that 0 2 controls zein synthesis through an intermediate step conditioned by 06.…”

A rapid method for determination of acid phosphatase activity of whole yeast cells

“…Acid phosphatase (EC 3.1.3.2) belongs to the group of enzymes that hydrolyse the phosphate esters thus providing inorganic phosphate (Pi) for the cells (Metzenberg 1979). Because they are easily assayed these enzymes represent good models for studying the gene expression of the maturation and excretion of transportable enzymes (Bajwa et al 1984).…”