Morphology and Genetics of a Periodic Colonial Mutant of Neurospora crassa

Sussman, Alfred S.; Lowry, Robert J.; Durkee, Thomas

doi:10.2307/2440293

Cited by 31 publications

(16 citation statements)

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“…These experiments further document the fundamental differences (16) between the bd strain and the clock strain of Neurospora (20) which has a rhythm effectively controlled (both expression and period) by such medium components. The rhythm of clock is considered to be non-circadian because of its insensitivity to light and sensitivity to temperature.…”

Section: Discussionmentioning

confidence: 62%

Effects of Medium Composition and Carbon Dioxide on Circadian Conidiation in Neurospora

1972

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Efforts to significantly perturb the timing mechanism, and thus the period, of the rhythm responsible for circadian conidiation in bd, a strain of Neurospora crassa, by altering the medium composition have been unsuccessful. Various salt solutions, sugars, and amino acids do, however, have pronounced effects on growth and conidiation, and thus on the expression and persistence of rhythmicity.Aeration August, 1970. perturb the postulated timing mechanism is to vary the growth medium. In general, perturbing the metabolism of an organism has little effect on its circadian rhythmicity (9), but changes in rhythm expression and period have been demonstrated in certain strains of Neurospora and other fungi by supplementing the growth medium with appropriate sugars and amino acids (3, 5, 10).The work reported here was initiated to determine if varying the growth medium would provide useful information about the mechanisms responsible for the bd rhythmicity. The experiments provide a better understanding of the band-gene role in Neurospora rhythmicity, and suggest that aeration is an important variable in the expression of Neurospora rhythmicity. The effects of aeration provide new insight into the occurrence of rhythmicity in Neurospora and the role of carbon dioxide in regulating conidiation of Neurospora cultures. MATERIALS AND METHODSStrains. A single-mutant strain, band (bd), which exhibits the timex phenotype on our standard glucose-arginine medium (16) was used throughout. This strain, MLS 41-4 (bd, a), was isolated after three backcrosses of the original bd (E7a) into the St. Lawrence wild-type, 74-OR 23-1A. The sources of the other wild-type and exotic strains used have been reported, as have the methods of stock maintenance and preservation (18).Media. The media contained Vogel's salts (22), 1.5% Difco Bacto-agar (unless otherwise stated), and the supplements listed. All percentage designations for media are weight per volume. The media were prepared, autoclaved, and dispensed (8 ml/tube) into 55-cm Pyrex growth-tubes stoppered with cotton. Heat-labile amino acids were filter sterilized and added to warm medium (45-50 C) before dispensing.Growth Conditions. Growth-tube cultures were inoculated, incubated 18 to 20 hr at room temperature in the light, and then placed in continuous darkness at 25 C. Scoring of rhythmicity and period calculations have been described previously (16, 18

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Section: Discussionmentioning

confidence: 62%

Effects of Medium Composition and Carbon Dioxide on Circadian Conidiation in Neurospora

1972

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“…Among the fungi, a number of noncircadian rhythms in development have been described (for review, see Bünning 1973) in otherwise wild-type strains. An early example is the clock strain (Sussman et al 1964(Sussman et al , 1965, identified as producing a rhythm in growth when cultured in race tubes, but later shown to not be circadian (Feldman and Hoyle 1974).…”

Section: Frq-less Oscillators and Other Noncircadian Feedback Loopsmentioning

confidence: 99%

Circadian Output, Input, and Intracellular Oscillators: Insights into the Circadian Systems of Single Cells

Loros¹,

Dunlap²,

Larrondo³

et al. 2007

Cold Spring Harbor Symposia on Quantitative Biology

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Circadian output comprises the business end of circadian systems in terms of adaptive significance. Work on Neurospora pioneered the molecular analysis of circadian output mechanisms, and insights from this model system continue to illuminate the pathways through which clocks control metabolism and overt rhythms. In Neurospora, virtually every strain examined in the context of rhythms bears the band allele that helps to clarify the overt rhythm in asexual development. Recent cloning of band showed it to be an allele of ras-1 and to affect a wide variety of signaling pathways yielding enhanced light responses and asexual development. These can be largely phenocopied by treatments that increase levels of intracellular reactive oxygen species. Although output is often unidirectional, analysis of the prd-4 gene provided an alternative paradigm in which output feeds back to affect input. prd-4 is an allele of checkpoint kinase-2 that bypasses the requirement for DNA damage to activate this kinase; FRQ is normally a substrate of activated Chk2, so in Chk2 , FRQ is precociously phosphorylated and the clock cycles more quickly. Finally, recent adaptation of luciferase to fully function in Neurospora now allows the core FRQ/WCC feedback loop to be followed in real time under conditions where it no longer controls the overt rhythm in development. This ability can be used to describe the hierarchical relationships among FRQ-Less Oscillators (FLOs) and to see which are connected to the circadian system. The nitrate reductase oscillator appears to be connected, but the oscillator controlling the longperiod rhythm elicited upon choline starvation appears completely disconnected from the circadian system; it can be seen to run with a very long noncompensated 60-120-hour period length under conditions where the circadian FRQ/WCC oscillator continues to cycle with a fully compensated circadian 22-hour period.

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“…We did not attempt to obtain numerical values for perithecial densities in our experiments, and have scored the plates between "O" for no initials detectable even by microscopic observations, to "--+ + " for the perithecial density found in our control cultures as given above. It was also noted for each plate and tube whether perithecial initiation or (35), except for the fact.' that these chang-es did not take place synchronoul\--, and that the periods in our case were of 2 to 3 hiouirs duiration, as against being circadian in the mutants.…”

Section: Methodsmentioning

confidence: 99%

Selective Effects of Purine and Pyrimidine Analogues and of Respiratory Inhibitors on Perithecial Development and Branching in Sordaria

Lindenmayer

Schoen

1967

Plant Physiol.

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Sumimtary. The initiation of perithecia in the homothallic ascomycete Sordaria fimiiicola was completely suppressed, without seriously inhibiting vegetative growth, by growing the fungus on an agar medium containing one of the following additions: 1) 1 uM 5-fluorouracil, 2) 10 to 100 jum 6-azauracil, 8-azaguanine or 8-azaadenine, 3) 50 to 500 uM cyanide or azide, 4) 5 % (w/,v) casein 'hydrolysate. In contrast to the selective activity of the analogues of 3 RNA bases, whose inhibition could be reversed by the appropriate normal bases only, none of the analogues of thymine were active, neither were the thio-derivatives of RNA bases. Other inhibitors of RNA and protein synthesis, like actinomycin D, puromycin and cycloheximide, were also without selective activity, although the last of these inhibited perithecial maturation at 0.1 um concentration but not initiation. Amino acid analogues were inactive, as were the metabolic inhibitors thiourea, 2,4-dinitrophenol and fluoride. The compounds which inhibited the formation of perithecia also lowered the branching frequencv of leading hyphae, but not their linear growth rates. Consequently, the branch (lensities wvere diminished in their presence. Hypotheses to account for these findings are discussed in terms of inhibition of growth in general, of the synthesis of some specific messenger RNAs, and of RNA-mediated transport across membranes, the last of which seeming the most fruitful for further work.Purine and pyrimidine analogues have been found to intervene at crucial developmental stages in both plants and animals. One of the most direct of these effects on p'aants was the suppression by some of the RNA base analogues of the normal sheet-like (cordate) growth of fern gametophytes while permitting their continued filamentous growth (3,20,21,22,29,30). None of the strictly DNA base analogues had such effect (29). Actinomycin D was effective (30), and so were 2 amino acid analogues, 5-methyltryptophane and ethionine (20-22), but not any of the common respiratory and glycolytic inhibitors (20). The leaf morphology of a water fern could be affected by application of 5-fluorouracil and 2-thiouracil, in the sense that normal lobation was suppressed and the characteristic sunken stomata of the land-form were favored (39). Similarly, 2-thiouracil affected leaf morphogenesis in flowering plants (17), and 5-fluorouracil has been demonstrated as an inhibitor of flower induction (8).

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Morphology and Genetics of a Periodic Colonial Mutant of Neurospora crassa

Cited by 31 publications

References 0 publications

Effects of Medium Composition and Carbon Dioxide on Circadian Conidiation in Neurospora

Effects of Medium Composition and Carbon Dioxide on Circadian Conidiation in Neurospora

Circadian Output, Input, and Intracellular Oscillators: Insights into the Circadian Systems of Single Cells

Selective Effects of Purine and Pyrimidine Analogues and of Respiratory Inhibitors on Perithecial Development and Branching in Sordaria

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