At first, the saprophytic eukaryote Neurospora crassa and the photosynthetic prokaryote Synechococcus elongatus may seem to have little in common. However, in both organisms a circadian clock organizes cellular biochemistry, and each organism lends itself to classical and molecular genetic investigations that have revealed a detailed picture of the molecular basis of circadian rhythmicity. In t...

The distribution and localization of structural polymers in the cell wall of Neurospora crassa has been studied by selective removal and light and electron microscope examination. Observations with the light microscope indicated that each polymer by itself can provide structural integrity to the cell wall. Examination by electron microscopy showed that the cell wall consists of an outer layer o...

Mycelia and ungerminated conidia of Neurospora crassa were found to secrete extracellular endocellulase (EC 3.2.1.4). A simple induction system of potassium phosphate buffer (ph 6.0) plus inducer relied on the internal metabolic reserves of conicia or mycelia to provide energy and substrates for protein synthesis. Buffer concentration for optimum enzyme production was 100 mM, but at higher buff...

With the realization in 1940 (1) that structural analogues of a metabolite frequently prevent utilization of that metabolite, it became possible to develop antimetabolites which block specific biosynthetic pathways. By blocking various steps in a biosynthetic pathway, antimetabolites are useful for elucidating intermediary metabolism. It was the object of the present study to investigate the bi...

Circadian systems include slave oscillators and central pacemakers, and the cores of eukaryotic circadian clocks described to date are composed of transcription and translation feedback loops (TTFLs). In the model system Neurospora, normal circadian rhythmicity requires a TTFL in which a White Collar complex (WCC) activates expression of the frequency (frq) gene, and the FRQ protein feeds back ...

Incubation of mitochondria from Neurospora crassa and Saccharomyces cerevisiae with the radioactive ATPase inhibitor [14C]dicyclohexylcarbodiimide results in the irreversible and rather specific labelling of a low-molecular-weight polypeptide. This dicyclohexylcarbodiimide-binding protein is identical with the smallest subunit (Mr 8000) of the mitochondrial ATPase complex, and it occurs as olig...

When Neurospora crassa is grown in the presence of Cu(II) ions, it accumulates the metal with the concomitant synthesis of a low molecular weight copper-binding protein. The molecule binds 6 g-atom of copper per mole protein (Mr = 2200) and shows a striking sequence homology to the zinc- and cadmium-binding vertebrate metallothioneins. Absorption, circular dichroism, and electron paramagnetic r...

U NDER the title “Fifty Years Ago: The Neurospora Revolution,” HOROWITZ (1 99 1) has celebrated an anniversary of the epochal 1941 paper of BEADLE and TATUM, which reported the first mutants with biochemically defined nutritional requirements. HOROWITZ’S account and others (HOROWITZ 1973, 1985, 1990; LEDERBERC 1990) have focused on the people who were involved, the genesis of their ideas, and t...

In vitro assembly or complementation of a hybrid assimilatory nitrate reductase was attained by mixing a preparation of nitrate-induced N. crassa mutant nit-1 specifically with acid-treated (pH 2.5) bovine milk or intestinal xanthine oxidase, rabbit liver aldehyde oxidase, or chicken liver xanthine dehydrogenase. The complementation reaction specifically required induced nit-1, the only nitrate...

FREQUENCY (FRQ), a key component of the Neurospora circadian clock, is progressively phosphorylated after its synthesis. Previously, we identified casein kinase II (CKII) as a kinase that phosphorylates FRQ. Disruption of the catalytic subunit of CKII abolishes the clock function; it also causes severe defects in growth and development. To further establish the role of CKII in clock function, o...