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.

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.

scholarly journals Isolation of Neurospora crassa A mating type mutants by repeat induced point (RIP) mutation.

Genetics ◽  
1992 ◽  
Vol 132 (1) ◽  
pp. 125-133 ◽  
Author(s):  
N L Glass ◽  
L Lee
Keyword(s):  
Neurospora Crassa ◽  
Mating Type ◽  
Single Copy ◽  
Open Reading Frame ◽  
Sexual Cycle ◽  
Reading Frame ◽  
Heterokaryon Incompatibility ◽  
Functional Regions ◽  
A Genome ◽  
Ascospore Formation

Abstract In the filamentous fungus, Neurospora crassa, mating type is regulated by a single locus with alternate alleles, termed A and a. The mating type alleles control entry into the sexual cycle, but during vegetative growth they function to elicit heterokaryon incompatibility, such that fusion of A and a hypha results in death of cells along the fusion point. Previous studies have shown that the A allele consists of 5301 bp and has no similarity to the a allele; it is found as a single copy and only within the A genome. The a allele is 3235 bp in length and it, too, is found as a single copy within the a genome. Within the A sequence, a single open reading frame (ORF) of 288 amino acids (mt A-1) is thought to confer fertility and heterokaryon incompatibility. In this study, we have used repeat induced point (RIP) mutation to identify functional regions of the A idiomorph. RIP mutations in mt A-1 resulted in the isolation of sterile, heterokaryon-compatible mutants, while RIP mutations generated in a region outside of mt A-1 resulted in the isolation of mutants capable of mating, but deficient in ascospore formation.

scholarly journals Evaluation of the Hematoxylin Staining Method for Detecting Wheat Tolerance to Alumlnum

1981 ◽  
Vol 31 (2) ◽  
pp. 152-160 ◽  
Author(s):  
Hiroko TAKAGI ◽  
Hyoji NAMAI ◽  
Kan-ichi MURAKAMI
Keyword(s):  
Staining Method ◽  
Hematoxylin Staining

scholarly journals A MEIOTIC UV-SENSITIVE MUTANT THAT CAUSES DELETION OF DUPLICATIONS IN NEUROSPORA

Genetics ◽  
1978 ◽  
Vol 89 (2) ◽  
pp. 245-269
Author(s):  
Dorothy Newmeyer ◽  
Donna R Galeazzi
Keyword(s):  
Neurospora Crassa ◽  
Single Gene ◽  
Complete Loss ◽  
Duplicate Segment ◽  
Sensitive Mutant ◽  
Rearrangement Breakpoint ◽  
Ascospore Formation

ABSTRACT The meiotic-3 (mei-3) mutant of Neurospora crassa has several effects: (1) When homozygous, it almost completely blocks meiosis and ascospore formation, (2) it is sensitive to UV, (3) its growth is inhibited by histidine and, (4) it increases the instability of nontandem duplications. This was shown for duplications produced by five different rearrangements and was demonstrated by two different criteria. The effects on meiosis and duplication instability are expressed strongly at 25°; the effects on sensitivity to UV and to histidine are expressed strongly at 38.5° but only slightly at 25°. Nevertheless, all four effects were shown to be due to a single gene. mei-3 is not allelic with previously reported UV-sensitive mutants.—Two other results were obtained that are not necessarily due to mei-3: (1) A cross involving mei-3 produced a new unlinked meiotic mutant, mei-4, which is not sensitive to UV or histidine, and (2) a burst of several new mutants occurred in a different mei-3 stock, including a partial revertant of mei-3.—mei-3 has previously been shown to cause frequent complete loss of a terminal duplicate segment, beginning exactly at the original rearrangement breakpoint. Possible mechanisms are discussed by which a UV-sensitive mutant could cause such precise deletions.

scholarly journals Evaluation of microscopic protocols for somatic cell counts in milk of dairy sheep

2018 ◽  
Vol 85 (0) ◽  
Author(s):  
Cristiane Rosa Moraes ◽  
Tatiana Regina Vieira ◽  
Andrea Troller Pinto ◽  
Verônica Schmidt
Keyword(s):  
Somatic Cell ◽  
Cell Count ◽  
Somatic Cell Count ◽  
Staining Method ◽  
Dairy Sheep ◽  
Carnoy’S Solution ◽  
Cell Counts ◽  
Glass Slides ◽  
Ewe's Milk ◽  
Microscope Slides

ABSTRACT: The somatic cell count (SCC) is a diagnostic tool that indicates the mammary gland health and can be determined by the counting of cells in the microscope. There are discussions regarding appropriate staining method to the ewes’ milk. The present study aimed to identify a methodology of microscopic SCC proper to the milk of the ovine species. Therefore, glass slides for smear were manufactured with 10 µL of ewe’s milk in 1 cm2, and the fixers xylol and Carnoy’s solution were tested, as well as and May-Grünwald, Broadhurst-Paley, Wrigth and Panoptic stainings. Carnoy’s solution was elected, because it allowed a better fixation of the dairy film to the microscope slides, and Broadhurst-Paley staining, due to its good coloration and visualization of cells, as well as the differentiation of cytoplasmic corpuscles in ewe’s milk. Broadhurst-Paley coloration is a tool applicable to the somatic cell count in ovine specie’s milk.

scholarly journals A Simple Nuclear Contrast Staining Method for MicroCT-Based 3D Histology Using Lead(II) Acetate

2020 ◽  
Author(s):  
Brian Metscher
Keyword(s):  
3D Imaging ◽  
Staining Method ◽  
Prima Facie ◽  
Cell Nuclei ◽  
Staining Solution ◽  
X Ray ◽  
Hematoxylin Staining ◽  
Basic Protocol ◽  
Cell Components ◽  
Local Cell

ABSTRACTX-ray microtomography (microCT) enables histological-scale 3D imaging of many types of biological samples, but it has yet to rival traditional histology for differentiation of tissue types and cell components. This report presents prima facie results indicating that a simple lead(II) acetate staining solution can impart preferential X-ray contrast to cell nuclei. While not strictly selective for nuclei, the staining reflects local cell-density differences. It can be applied in a single overnight treatment and does not require hematoxylin staining or drying of the sample. The stain is removable with EDTA, and it may enhance early calcifications. A basic protocol is given as a guide for further testing and optimisation.

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