ROSELLINIA LIMONIISPORA: NUCLEAR CHANGES IN THE DEVELOPING ASCUS

1964 ◽  
Vol 42 (1) ◽  
pp. 13-21 ◽  
Author(s):  
David S. Hayman
Keyword(s):  
Daughter Nucleus ◽  
Nuclear Division ◽  
General Pattern ◽  
Late Pachytene ◽  
Homologous Chromosomes ◽  
Nuclear Cycle ◽  
Fusion Nucleus ◽  
Nuclear Changes ◽  
A Cell ◽  
Rapid Elongation

The nuclear cycle in the developing ascus of Rosellinia limoniispora, as revealed in aceto-orcein and acetocarmine smears, follows the general pattern for the higher Ascomycetes: crozier formation, early synapsis of homologous chromosomes in the fusion nucleus followed by nucleolar fusion, rapid elongation of chromosomes and ascus up to late pachytene of prophase I followed by contraction of the chromosomes and nucleolus, and the formation of eight nuclei as a result of two meiotic and one mitotic divisions. The orientation of nuclei in divisions II and III is haphazard. Ascospore delimitation is by simple cleavage of the cytoplasm; no centriole – astral ray mechanism was observed. A nuclear division occurs in each young ascospore, one daughter nucleus being cut off into a cell and degenerating.

An Ultrastructural and Radioautographic Study of Early Oogenesis in the Toad Xenopus Laevis

1973 ◽  
Vol 12 (1) ◽  
pp. 71-93
Author(s):  
LESLEY WATSON COGGINS
Keyword(s):  
Electron Microscope ◽  
Xenopus Laevis ◽  
Thymidine Incorporation ◽  
Ultrastructural Level ◽  
Extrachromosomal Dna ◽  
Late Pachytene ◽  
Synaptonemal Complexes ◽  
Round Nucleus ◽  
A Cell ◽  
Major Period

Early oogenesis in the toad Xenopus laevis has been investigated at the ultrastructural level, with particular reference to the formation of extrachromosomal DNA. Thymidine incorporation was localized by electron microscope radioautography. In oogonia, the nucleus is irregular in outline and may contain several nucleoli. Oocytes, from premeiotic interphase to late pachytene, are found in cell nests which are estimated to consist of about 16 cells each. Adjacent oocytes within a nest are connected by intercellular bridges and develop synchronously. Each premeiotic interphase-leptotene oocyte has a round nucleus which contains one or two centrally located, spherical nucleoli. Electron-microscope radioautography showed that all nuclei in a cell nest incorporate thymidine synchronously during premeiotic S-phase. In zygotene oocytes, axial cores and synaptonemal complexes are observed in the nucleus and abut against the inner nuclear membrane in the region nearest the centre of the cell nest. The nucleolus is still more-or-less round in outline, but is asymmetrically positioned in the nucleus. It lies near the nuclear envelope on the side of the nucleus furthest away from the attachment of the chromosome ends, that is, nearest the outside of the cell nest. Each nucleolus is surrounded by a fibrillar ‘halo’ of nucleolus-associated chromatin into which a low level of thymidine incorporation occurs during zygotene. This is thought to represent the start of the major period of amplification of the ribosomal DNA. Pachytene is characterized by the presence of synaptonemal complexes in the nucleus. The nucleolus becomes very irregular in outline. The fibrillar area around it, which represents the extrachromosomal DNA, increases in size and thymidine is incorporated over the whole of this region. In late pachytene, many small fibrogranular bodies, the multiple nucleoli, are formed in it. The members of a cell nest become separated from one another at this time and begin to develop asynchronously. In diplotene, synaptonemal complexes are no longer observed in the nucleus. The most prominent structures in the nucleus are now the multiple nucleoli, which increase greatly in number in early diplotene. A large increase in cytoplasmic volume occurs and the oocyte grows in size.

scholarly journals KCTD19 and its associated protein ZFP541 are independently essential for meiosis in male mice

PLoS Genetics ◽  
2021 ◽  
Vol 17 (5) ◽  
pp. e1009412
Author(s):  
Seiya Oura ◽  
Takayuki Koyano ◽  
Chisato Kodera ◽  
Yuki Horisawa-Takada ◽  
Makoto Matsuyama ◽  
...  
Keyword(s):  
Dna Damage ◽  
Reproductive Tract ◽  
Zinc Finger Protein ◽  
Male Mice ◽  
Late Pachytene ◽  
Histone Deacetylase 1 ◽  
Tetramerization Domain ◽  
Evolutionarily Conserved ◽  
Division Process ◽  
A Cell

Meiosis is a cell division process with complex chromosome events where various molecules must work in tandem. To find meiosis-related genes, we screened evolutionarily conserved and reproductive tract-enriched genes using the CRISPR/Cas9 system and identified potassium channel tetramerization domain containing 19 (Kctd19) as an essential factor for meiosis. In prophase I, Kctd19 deficiency did not affect synapsis or the DNA damage response, and chiasma structures were also observed in metaphase I spermatocytes of Kctd19 KO mice. However, spermatocytes underwent apoptotic elimination during the metaphase-anaphase transition. We were able to rescue the Kctd19 KO phenotype with an epitope-tagged Kctd19 transgene. By immunoprecipitation-mass spectrometry, we confirmed the association of KCTD19 with zinc finger protein 541 (ZFP541) and histone deacetylase 1 (HDAC1). Phenotyping of Zfp541 KO spermatocytes demonstrated XY chromosome asynapsis and recurrent DNA damage in the late pachytene stage, leading to apoptosis. In summary, our study reveals that KCTD19 associates with ZFP541 and HDAC1, and that both KCTD19 and ZFP541 are essential for meiosis in male mice.

Cytogenetics of decaploid Agropyron elongatum (Elytrigia elongata) (2n = 70). I. Frequency of decavalent formation

Genome ◽  
1990 ◽  
Vol 33 (6) ◽  
pp. 811-817 ◽  
Author(s):  
Mikio Muramatsu
Keyword(s):  
High Frequency ◽  
Chromosome Association ◽  
Agropyron Elongatum ◽  
Homologous Chromosomes ◽  
Ring Shape ◽  
Meiotic Configuration ◽  
Multivalent Formation ◽  
A Cell ◽  
Chromosome Associations ◽  
Metaphase I

The multivalents that appeared in the decaploid strain of Agropyron elongatum (2n = 10x = 70), a relative of wheat, ranged from trivalent to decavalent. Few univalents occurred. The metaphase I chromosome association in 12 cells where all configurations could clearly be identified averaged 0.42 ring X + 0.17 chain X + 0.42 ring VIII + 0.17 branched VIII + 0.25 chain VIII + 0.17 chain VII + 1.17 ring VI + 0.33 branched VI + 0.5 chain VI + 1.67 ring IV + 0.42 branched IV + 0.58 chain IV + 0.08 branched III + 0.17 chain III + 12.58 ring II + 3.75 open II + 0.25 I. The occurrence of decavalents, up to two in one cell, and of a cell with five multivalents, each of which involved more than five chromosomes, and many multivalents of ring shape indicated that the strain is autodecaploid.The chromosome associations of each cell can be interpreted as seven groups of 10 homologous chromosomes. The high frequency of bivalents indicated a tendency toward reduced multivalent formation, for which an explanation is suggested.Key words: Agropyron elongatum, meiotic configuration, decaploid, multivalent.

Nuclear distribution and behavior in Thielaviopsis basicola

1972 ◽  
Vol 50 (12) ◽  
pp. 2423-2429 ◽  
Author(s):  
H. C. Huang ◽  
Z. A. Patrick
Keyword(s):  
Daughter Nucleus ◽  
Nuclear Division ◽  
Mitotic Division ◽  
Thielaviopsis Basicola ◽  
Cytological Investigation ◽  
A Chain ◽  
And Behavior ◽  
Septal Pores ◽  
Derivatives Of ◽  
Mycelial Cell

A cytological investigation of four biotypes of Thielaviopsis basicola isolated from field soil and of three cultural variants revealed that the hyphal cells, conidiophores, endoconidia, and chlamydospores are regularly uninucleate except those cells in which nuclear division or nuclear migration has occurred.The nucleus in the end cell of the conidiophore divides mitotically and successively after cell division to produce a chain of uninucleate endoconidia. During the formation of chlamydospores, a daughter nucleus migrates from the mycelial cell into the chlamydospore primordium. This primordium later forms a one-celled chlamydospore. If the chlamydospore consists of more than one cell, all the nuclei in the cells are derivatives of the nucleus in the primordium.Nuclear migration from one cell to another was observed to take place by means of anastomosis and (or) through septal pores of the mycelia. Anastomosis occurs between mycelia, between endoconidia, and between a mycelium and an endoconidium.The entire process of mitotic division occurs within an intact nuclear envelope. An intranucleate spindle was demonstrated in dividing nuclei in living preparations. Stained preparations revealed that there are four chromosomes in T. basicola.

scholarly journals AN ENDOMITOTIC EFFECT OF A CELL CYCLE MUTATION OF SACCHAROMYCES CEREVISIAE

Genetics ◽  
1981 ◽  
Vol 97 (3-4) ◽  
pp. 551-562 ◽  
Author(s):  
David Schild ◽  
Honnavara N Ananthaswamy ◽  
Robert K Mortimer
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Genetic Analysis ◽  
Nuclear Division ◽  
Pedigree Analysis ◽  
Visual Observation ◽  
Temperature Sensitive ◽  
Cell Stage ◽  
Haploid Strain ◽  
A Cell ◽  
Dna Measurements

ABSTRACT A recessive temperature-sensitive mutation of Saccharomyces cerevisiae has been isolated and shown to cause an increase in ploidy in both haploids and diploids. Genetic analysis revealed that the strain carrying the mutation was an aa diploid, although MNNG mutagenesis had been done on an a haploid strain. When the mutant strain was crossed with an aa diploid and the resultant tetraploid sporulated, some of the meiotic progeny of this tetraploid were themselves tetraploid, as shown by both genetic analysis and DNA measurements, instead of diploid as expected of tetraploid meiosis. The ability of these tetraploids to continue to produce tetraploid meiotic progeny was followed for four generations. Homothallism was excluded as a cause of the increase in ploidy; visual pedigree analysis of spore clones to about the 32-cell stage failed to reveal any zygotes, and haploids that diploidized retained their mating type. An extra round of meiotic DNA synthesis was also considered and excluded. It was found that tetraploidization was independent of sporulation temperature, but was dependent on the temperature of germination and the growth of the spores. Increase in ploidy occurred when the spores were germinated and grown at 30°, but did not occur at 23°. Two cycles of sporulation and growth at 23° resulted in haploids, which were shown to diploidize within 24 hr when grown at 30°. Visual observation of the haploid cells incubated at 36° revealed a celldivisioncycle phenotype characteristic of mutations that affect nuclear division; complementation analysis demonstrated that the mutation, cdc31-2, is allelic to cdc31-1, a mutation isolated by HARTWEeLL et al.(1973) and characterized as causing a temperature-sensitive arrest during late nuclear division. The segregation of cdc31-2 in heterozygous diploids was 2:2 and characteristic of a noncentromere-linked gene.

scholarly journals The Investigation of Antimutagenic Effects on Chromosomes and Cell Division Mechanisms against Mitomycine C in Human Lymphocyte Culture of Liquid Extracts Obtained from Blueberry (Vaccinium myrtillus L.) and Raspberry (Rubus idaeus L.)

2020 ◽  
pp. 1-14
Author(s):  
Müge Mavioğlu Kaya ◽  
Süleyman Gül
Keyword(s):  
Culture Medium ◽  
Nuclear Division ◽  
Rubus Idaeus ◽  
Control Group ◽  
Cell Culture Medium ◽  
Blood Samples ◽  
A Cell ◽  
Group Ii ◽  
Vaccinium Myrtillus L ◽  
Control Group Group

Aims: In this study, we determined that whether the liquid extracts of the above-ground parts of Vaccinium myrtillus L. and Rubus idaeus L. have antimutagenic effects against mitomycin C in human peripheral lymphocytes, chromosome aberration (CA), micronucleus (MN) and mitotic index (MI) tests. Methodology: Blood samples of the negative control group (Group I) were allowed to react in a cell culture medium without any treatment, while positive control group (Group II) was allowed to interact in a cell culture medium supplemented with mitomycin-C (MMC) at a dose of 0.3 μL /mL for each chromosome medium. Blood samples of the other groups were allowed to react for 24 hours with 0.3 μL /mL MMC and V. myrtillus L. (Group III, IV, V and VI), and R. idaeus L. (VII, VIII, IX and X) extracts in 0.2 μL /mL, 0.4 μL /mL, 0.8 μL /mL and 1.6 μL /mL doses for each of cell cultures. At the end of the incubation period, culture cells were evaluated by chromosomal aberrations, mitotic, micronucleus and nuclear division index tests. Results: Compared with Group II, it was determined that mitotic, nuclear division and nuclear cytotoxic cleavage indices were increased when chromosome aberrations and micronucleus indexes were decreased in extract groups. When we compared to extract groups and group II, we observed that chromosome aberrations and micronucleus index decreased in extract groups, while mitotic, nuclear division and nuclear cytotoxic cleavage indices were increased. Conclusion: It was concluded that aqueous extracts of V. myrtillus L. and Rubus idaeus L. had significantly antimutagenic effects on the human peripheral lymphocyte cells at the working doses.

Somatic nuclear division in the sporidia of Ustilago violacea. III. Ultrastructural observations

1976 ◽  
Vol 22 (4) ◽  
pp. 495-506 ◽  
Author(s):  
N. H. Poon ◽  
A. W. Day
Keyword(s):  
Daughter Cell ◽  
Daughter Nucleus ◽  
Nuclear Division ◽  
Spindle Pole ◽  
The Other ◽  
Parent Cell ◽  
Electron Microscopic ◽  
Ustilago Violacea ◽  
Left Behind ◽  
Spindle Pole Bodies

The paper provides detailed ultrastructural observations on nuclear division in the smut fungus Ustilago violacea and is based on previous light-microscopic work outlining the division in living and stained cells. The division as in many other Basidiomycetes is not intranuclear, but occurs within a partially disrupted membrane. The division takes place after migration of most of the nucleus into the bud cell, after limited breakdown of the nuclear membrane, and after the formation of a spindle between two spindle-pole bodies (SPB). The remaining part of the nucleus containing the nucleolus is left behind in the parent cell and degenerates there. The SPB, as in other Basidiomycetes, is a dome-shaped relatively structureless body, quite distinct from the flat plaques of many Ascomycetes and the elaborate centrioles of Phycomycetes. The SPB divides shortly before migration into the daughter cell and invariably is located at the apex of the migrating nucleus. Nuclear division is completed when the two masses of chromatin clustered about each of the SPB's are separated as the spindle elongates. One daughter nucleus reforms in the bud and the other is reformed in the mother cell.Cells fixed and stained by conventional light-microscopic methods were examined in the light of the electron-microscopic observations to determine whether these procedures induce artefacts. Aceto-orcein and Giemsa when used cold were found to produce relatively artefact-free preparations. However, previous results in which the cells were warmed gently in these stains are now seen to contain artefacts in the form of contracted chromatinic granules often arranged in chains. These artefacts may provide useful information but clearly they must be interpreted cautiously until the nature of the changes induced by heating are known.

scholarly journals Translational control of lipogenesis links protein synthesis and phosphoinositide signaling with nuclear division

2021 ◽  
Author(s):  
Nairita Maitra ◽  
Staci Hammer ◽  
Clara Kjerfve ◽  
Vytas A. Bankaitis ◽  
Michael Polymenis
Keyword(s):  
Cell Cycle ◽  
Translational Control ◽  
Fatty Acid Synthase ◽  
Nuclear Division ◽  
Phosphoinositide Signaling ◽  
Signaling Axis ◽  
Dividing Cells ◽  
A Cell ◽  
Phosphatidylinositol Transfer ◽  
Phosphatidylinositol 4

ABSTRACTContinuously dividing cells coordinate their growth and division. How fast cells grow in mass determines how fast they will multiply. Yet, there are few, if any, examples of a metabolic pathway that actively drives a cell cycle event instead of just being required for it. Here, we show that translational upregulation of lipogenic enzymes in yeast increased the abundance of lipids and accelerated nuclear elongation and division. De-repressing translation of acetyl CoA carboxylase and fatty acid synthase also suppressed cell cycle-related phenotypes, including delayed nuclear division, associated with Sec14p phosphatidylinositol transfer protein deficiencies, and the irregular nuclear morphologies of mutants defective in phosphatidylinositol 4-OH kinase activities. Our results show that increased lipogenesis drives a critical cell cycle landmark and report a phosphoinositide signaling axis in control of nuclear division. The broad conservation of these lipid metabolic and signaling pathways raises the possibility these activities similarly govern nuclear division in mammals.

Mutations of the fizzy locus cause metaphase arrest in Drosophila melanogaster embryos

Development ◽  
1993 ◽  
Vol 117 (1) ◽  
pp. 359-376 ◽  
Author(s):  
I.A. Dawson ◽  
S. Roth ◽  
M. Akam ◽  
S. Artavanis-Tsakonas
Keyword(s):  
Cell Cycle ◽  
Cell Death ◽  
Drosophila Melanogaster ◽  
Double Mutant ◽  
Nuclear Division ◽  
Normal Function ◽  
Metaphase Arrest ◽  
Nervous Systems ◽  
Dividing Cells ◽  
A Cell

We describe the effects of mutations in the fizzy gene of Drosophila melanogaster and show that fizzy mutations cause cells in mitosis to arrest at metaphase. We show that maternally supplied fizzy activity is required for normal nuclear division in the preblastoderm embryo and, during later embryogenesis, that zygotic fizzy activity is required for the development of the ventrally derived epidermis and the central and peripheral nervous systems. In fizzy embryos, dividing cells in these tissues arrest at metaphase, fail to differentiate and ultimately die. In the ventral epidermis, if cells are prevented from entering mitosis by using a string mutation, cell death is prevented and the ability to differentiate ventral epidermis is restored in fizzy; string double mutant embryos. These results demonstrate that fizzy is a cell cycle mutation and that the normal function of the fizzy gene is required for dividing cells to exit metaphase and complete mitosis.

Nuclear division and chromosome behavior during meiosis and ascosporogenesis in Pyricularia oryzae

1987 ◽  
Vol 65 (1) ◽  
pp. 112-123 ◽  
Author(s):  
Hei Leung ◽  
P. H. Williams
Keyword(s):  
Magnaporthe Grisea ◽  
Nuclear Division ◽  
Spindle Pole ◽  
Pyricularia Oryzae ◽  
Maximum Diameter ◽  
Chromosome Movement ◽  
Chromosome Behavior ◽  
Electron Microscopic ◽  
Homologous Chromosomes ◽  
Spindle Pole Bodies

Meiosis and mitoses during ascosporogenesis in fertile mating strains of Pyricularia oryzae Cavara (teleomorph: Magnaporthe grisea) were studied using a propionic–iron–hematoxylin procedure which stained chromosomes, nucleolus, and spindle pole bodies. Meioses and mitoses in P. oryzae resembled those in other ascomycetes. Zygotene chromosomes were highly contracted followed by elongation at pachytene when close pairings of homologous chromosomes were observed. Nucleoli attained a maximum diameter of 3.8 μm during pachytene. Nucleolar growth was accompanied by a rapid growth of the ascus. Chromosome lengths varied among pachytene cells, with the longest chromosome averaging 8.5 and the smallest 2.9 μm. Telomeric knobs and chromomeres were discernible on fully extended pachytene chromosomes. Six chromosomes were observed at pachytene and diakinesis, and during metaphase of ascospore mitosis. Chromosome movement at meiotic and mitotic anaphase was asynchronous, resulting in lagging chromosomes. Electron microscopic observations revealed spindle pole bodies associated with profusion and early meiotic prophase nuclei. In pachytene nuclei, 50 nm wide structures resembling synaptonemal complexes were observed.

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