CHARACTERISTICS OF DEVELOPING ASCI OF NEUROSPORA CRASSA

1965 ◽  
Vol 43 (8) ◽  
pp. 933-938
Author(s):  
Mary B. Mitchell
Keyword(s):  
Neurospora Crassa ◽  
Spore Formation ◽  
Immature Fruit ◽  
Nuclear Behavior ◽  
Nuclear Cycle

Morphology of the ascus and of the ascus cluster, as observed in carmine-stained, squash preparations of the contents of immature fruit bodies, is described with the aid of photomicrographs. Complications which raise questions regarding the applicability of the currently accepted scheme of ascus development are discussed. The function of the crozier, the mechanism of spore formation, and the correlation of nuclear behavior with ascus growth appear to have been misunderstood. It is concluded that the initial stages of ascus development involve complexities, the resolution of which may reveal unknown aspects of the nuclear cycle.

Aberrant nuclear behavior at meiosis and anucleate spore formation by sporulation-deficient (spo) mutants of Saccharomyces cerevisiae

1974 ◽  
Vol 83 (1) ◽  
pp. 166-174 ◽  
Author(s):  
P.B. Moens ◽  
Rochelle E. Esposito ◽  
M.S. Esposito
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Spore Formation ◽  
Nuclear Behavior

scholarly journals The nuclear cycle in bacteria

1949 ◽  
Vol 47 (2) ◽  
pp. 182-187 ◽  
Author(s):  
K. A. Bisset
Keyword(s):  
Life Cycle ◽  
Central Body ◽  
Spore Formation ◽  
Lag Phase ◽  
Vegetative Phase ◽  
Reduction Processes ◽  
Nuclear Cycle

1. Strains ofBact. coliand related bacteria possess a life cycle resembling that of Myxobacteria. The vesicular, resting nucleus is contained in a microcyst, which is formed by a process suggestive of sexual conjugation.2. The microcyst germinates by the transformation of the resting nucleus into the chromosome-like bodies typical of active, vegetative cultures. These may be analogous to the chromosome complexes of yeasts. The period of germination of microcysts corresponds to the lag phase of cultures.3. The nucleus remains permanently in the mitotic condition during the active, vegetative phase of growth, and reproduces by an asexual and a sexual method.4. Older cultures may be transformed directly into microcysts or may first adopt a secondary, vegetative phase, in which the nucleus is in the form of a single, central body.5. Microcyst formation differs from spore formation in that it lacks the obvious reduction processes associated with spore formation, upon which a few original observations are included.

scholarly journals Nuclear behavior in the vegetative hyphae of Neurospora crassa

1966 ◽  
Vol 10 (1) ◽  
Author(s):  
C. L. Wilson
Keyword(s):  
Neurospora Crassa ◽  
Nuclear Behavior

Meiotic nuclear behavior and ascospore formation in five homothallic species of Neurospora

1978 ◽  
Vol 56 (7) ◽  
pp. 754-763 ◽  
Author(s):  
Namboori B. Raju
Keyword(s):  
Neurospora Crassa ◽  
Chromosome Numbers ◽  
Staining Method ◽  
Carnoy’S Solution ◽  
Nuclear Behavior ◽  
Polar Caps ◽  
Single File ◽  
Apical Pore ◽  
Hematoxylin Staining ◽  
Ascospore Formation

Meiotic nuclear behavior and chromosome numbers have been examined, using a propionic–iron–hematoxylin staining method, in Neurospora crassa and in five homothallic species, N. africana, N. dodgei, N. galapagosensis, N. lineolata and N. tcrricola. Ascus development, haploid chromosome numbers (n = 7), and morphology in all five homothallic species resemble the heterothallic N. crassa. The following observations have not been reported previously for any Neurospora species, although some have been described in other fungi. Most observations apply to all five homothallic species and to N. crassa except where otherwise indicated. (1) Chromosomes elongate considerably between karyogamy and the beginning of synapsis, and leptotene and zygotene stages can be identified. (2) The ascus tip flattens, and an apical pore begins to form during diplotene. (3) After telophase III, when all eight nuclei line up in single file, the nuclei are always arranged perpendicularly to the ascus wall with all spindle plaques on the same side. All nuclei then tilt relative to the ascus base with the spindle plaques at the lower end; consequently, the spores become obliquely arranged. (4) Ascospores of N. terricola are initially spindle shaped and occupy the entire ascus but later become compact and ovoid with spaces between them. (5) Maturing ascospores grow two to four times their initial compacted size. (6) In the young ascus, the nucleolus usually orients toward the base. (7) In N. terricola, the nucleolus is frequently hemispherical, especially in the young asci. (8) Half-moon-shaped polar caps are sometimes visible, one on each side of the prophase I nucleus; these are most prominent in N. terricola. (9) Cytological preparations are greatly improved if hydrolyzed perithecia are thoroughly washed in a Carnoy's solution containing chloroform.

Ultrastructure and Morphology of the Neurospora Crassa Cell Wall Mutants, Slime And Slime X, Using Tem and Sem

1976 ◽  
Vol 34 ◽  
pp. 54-55
Author(s):  
Karen S. Howard ◽  
H. D. Braymer ◽  
M. D. Socolofsky ◽  
S. A. Milligan
Keyword(s):  
Cell Wall ◽  
Neurospora Crassa ◽  
Wild Type ◽  
Morphological Comparison ◽  
Small Areas ◽  
Solid Media ◽  
Thin Sectioning ◽  
X Cells ◽  
Mutant Cells ◽  
Isolated Cell

The recently isolated cell wall mutant slime X of Neurospora crassa was prepared for ultrastructural and morphological comparison with the cell wall mutant slime. The purpose of this article is to discuss the methods of preparation for TEM and SEM observations, as well as to make a preliminary comparison of the two mutants.TEM: Cells of the slime mutant were prepared for thin sectioning by the method of Bigger, et al. Slime X cells were prepared in the same manner with the following two exceptions: the cells were embedded in 3% agar prior to fixation and the buffered solutions contained 5% sucrose throughout the procedure.SEM: Two methods were used to prepare mutant and wild type Neurospora for the SEM. First, single colonies of mutant cells and small areas of wild type hyphae were cut from solid media and fixed with OSO4 vapors similar to the procedure used by Harris, et al. with one alteration. The cell-containing agar blocks were dehydrated by immersion in 2,2-dimethoxypropane (DMP).

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