A phase overshadowed by mitotic division: interphase

2021 ◽  
pp. 1-14
Author(s):  
Ayla Karataş
Keyword(s):  
Mitotic Division

Ultrastructure of primary spermatocyte in fish (Tilapia: Oreochromis niloticus): The synaptonemal complex

1986 ◽  
Vol 44 ◽  
pp. 288-289
Author(s):  
T. Guha ◽  
A. Q. Siddiqui ◽  
P. F. Prentis
Keyword(s):  
Fine Structure ◽  
Electron Microscope ◽  
Synaptonemal Complex ◽  
Oreochromis Niloticus ◽  
Short Communication ◽  
Primary Spermatocyte ◽  
Mitotic Division ◽  
Meiotic Cell ◽  
Electron Microscope Level ◽  
Homologous Chromosomes

The Primary Spermatocytes represent a stage in spermatogenesis when the first meiotic cell division occurs. They are derived from Spermatogonium or Stem cell through mitotic division. At the zygotene phase of meiotic prophase the Synaptonemal complex appears in these cells in the space between the paired homologous chromosomes. Spermatogenesis and sperm structure in fish have been studied at the electron microscope level in a few species? However, no work has yet been reported on ultrastructure of tilapia, O. niloticus, spermatozoa and spermatogenetic process. In this short communication we are reporting the Ultrastructure of Primary Spermatocytes in tilapia, O. niloticus, and the fine structure of synaptonemal complexes seen in the spermatocyte nuclei.

scholarly journals A Screen for Genes Involved in the Anaphase Proteolytic Pathway Identifies tsm1+, a Novel Schizosaccharomyces pombe Gene Important for Microtubule Integrity

Genetics ◽  
1998 ◽  
Vol 149 (3) ◽  
pp. 1251-1264
Author(s):  
Ekaterina L Grishchuk ◽  
James L Howe ◽  
J Richard McIntosh
Keyword(s):  
Schizosaccharomyces Pombe ◽  
Nuclear Division ◽  
Mitotic Division ◽  
Temperature Sensitive ◽  
Permissive Temperature ◽  
Anaphase Promoting Complex ◽  
Chloromethyl Ketone ◽  
Proteolytic Pathway ◽  
Functional Involvement ◽  
Spindle Elongation

Abstract The growth of several mitotic mutants of Schizosaccharomyces pombe, including nuc2-663, is inhibited by the protease inhibitor N-Tosyl-L-Phenylalanine Chloromethyl Ketone (TPCK). Because nuc2+ encodes a presumptive component of the Anaphase Promoting Complex, which is required for the ubiquitin-dependent proteolysis of certain proteins during exit from mitosis, we have used sensitivity to TPCK as a criterion by which to search for novel S. pombe mutants defective in the anaphase-promoting pathway. In a genetic screen for temperature-sensitive mitotic mutants that were also sensitive to TPCK at a permissive temperature, we isolated three tsm (TPCK-sensitive mitotic) strains. Two of these are alleles of cut1+, but tsm1-512 maps to a novel genetic location. The tsm1-512 mutation leads to delayed nuclear division at restrictive temperatures, apparently as a result of an impaired ability to form a metaphase spindle. After shift of early G2 cells to 36°, tsm1-512 arrests transiently in the second mitotic division and then exits mitosis, as judged by spindle elongation and septation. The chromosomes, however, often fail to segregate properly. Genetic interactions between tsm1-512 and components of the anaphase proteolytic pathway suggest a functional involvement of the Tsm1 protein in this pathway.

scholarly journals Mutational analyses of fs(1)Ya, an essential, developmentally regulated, nuclear envelope protein in Drosophila.

Genetics ◽  
1995 ◽  
Vol 141 (4) ◽  
pp. 1473-1481 ◽  
Author(s):  
J Liu ◽  
K Song ◽  
M F Wolfner
Keyword(s):  
Cell Cycle ◽  
Embryonic Development ◽  
Nuclear Envelope ◽  
Envelope Protein ◽  
Chromatin Condensation ◽  
Cell Cycle Control ◽  
Nuclear Lamina ◽  
Mitotic Division ◽  
Developmentally Regulated ◽  
Egg Maturation

Abstract The fs(1)Ya protein (YA) is an essential, maternally encoded, nuclear lamina protein that is under both developmental and cell cycle control. A strong Ya mutation results in early arrest of embryos. To define the function of YA in the nuclear envelope during early embryonic development, we characterized the phenotypes of four Ya mutants alleles and determined their molecular lesions. Ya mutant embryos arrest with abnormal nuclear envelopes prior to the first mitotic division; a proportion of embryos from two leaky Ya mutants proceed beyond this but arrest after several abnormal divisions. Ya unfertilized eggs contain nuclei of different sizes and condensation states, apparently due to abnormal fusion of the meiotic products immediately after meiosis. Lamin is localized at the periphery of the uncondensed nuclei in these eggs. These results suggest that YA function is required during and after egg maturation to facilitate proper chromatin condensation, rather than to allow a lamin-containing nuclear envelope to form. Two leaky Ya alleles that partially complement have lesions at opposite ends of the YA protein, suggesting that the N- and C-termini are important for YA function and that YA might interact with itself either directly or indirectly.

Mutations affecting the cytoskeletal organization of syncytial Drosophila embryos

Development ◽  
1993 ◽  
Vol 118 (4) ◽  
pp. 1245-1254 ◽  
Author(s):  
W. Sullivan ◽  
P. Fogarty ◽  
W. Theurkauf
Keyword(s):  
Mitotic Division ◽  
P Element ◽  
Drosophila Embryo ◽  
Nuclear Movement ◽  
Microtubule Organization ◽  
Cytoskeletal Organization ◽  
New Genes ◽  
Movement Organization ◽  
Cytoplasmic Organization ◽  
Drosophila Embryos

Cytoplasmic organization, nuclear migration, and nuclear division in the early syncytial Drosophila embryo are all modulated by the cytoskeleton. In an attempt to identify genes involved in cytoskeletal functions, we have examined a collection of maternal-effect lethal mutations induced by single P-element transposition for those that cause defects in nuclear movement, organization, or morphology during the syncytial embryonic divisions. We describe three mutations, grapes, scrambled, and nuclear-fallout, which define three previously uncharacterized genes. Females homozygous for these mutations produce embryos that exhibit extensive mitotic division errors only after the nuclei migrate to the surface. Analysis of the microfilament and microtubule organization in embryos derived from these newly identified mutations reveal disruptions in the cortical cytoskeleton. Each of the three mutations disrupts the actin-based pseudocleavage furrows and the cellularization furrows in a distinct fashion. In addition to identifying new genes involved in cytoskeletal organization, these mutations provide insights into cytoskeletal function during early Drosophila embryogenesis.

scholarly journals SDG2-Mediated H3K4me3 Is Crucial for Chromatin Condensation and Mitotic Division during Male Gametogenesis in Arabidopsis

2017 ◽  
Vol 174 (2) ◽  
pp. 1205-1215 ◽  
Author(s):  
Violaine Pinon ◽  
Xiaozhen Yao ◽  
Aiwu Dong ◽  
Wen-Hui Shen
Keyword(s):  
Chromatin Condensation ◽  
Mitotic Division ◽  
Male Gametogenesis

Ultrastructure of teliospores and promycelium and basidiospore formation in the two-spored form of Gymnoconia nitens, one of the causes of orange rust of Rubus

2007 ◽  
Vol 85 (10) ◽  
pp. 935-940 ◽  
Author(s):  
Charles W. Mims ◽  
Elizabeth A. Richardson
Keyword(s):  
Fluorescence Microscopy ◽  
Mitotic Division ◽  
Sequence Of Events ◽  
Transverse Septum ◽  
Rubus Argutus

Gymnoconia nitens (Schwein.) Kern & H. W. Thurston consists of two forms that cause orange rust of Rubus . The teliospores of both of these forms are morphologically identical to aeciospores, but upon germination form promycelia that give rise to either two or four basidiospores. In this study, we examined the teliospores and the sequence of events leading to basidiospore development in the two-spored form of G. nitens. The teliospores of this species are formed in chains from uninucleate sporogenous cells that line the base of each sorus on infected Rubus argutus Link. (blackberry) leaves. Fluorescence microscopy revealed that approximately 90% of the mature teliospores were uninucleate. During germination, the teliospore nucleus migrated into the developing promycelium and underwent a single mitotic division. A transverse septum formed between the two daughter nuclei creating two uninucleate cells. A tapered sterigma arose from each cell and gave rise to a basidiospore. These findings indicate that the basidiospores of the two-spored form of G. nitens were formed in an asexual fashion.

scholarly journals Megasporocyte formation in Pisum sativum L. against the back ground of bud development

2014 ◽  
Vol 50 (1-2) ◽  
pp. 169-172 ◽  
Author(s):  
Wanda Wojciechowska ◽  
Teresa Mackiewicz
Keyword(s):  
Pisum Sativum ◽  
Mitotic Division ◽  
Bud Development ◽  
Pisum Sativum L ◽  
Back Ground ◽  
Mother Cells

Megasporocyte formation in <em>Pisum sativum</em> L. takes place at the stages of bud development, when the vexillum surpasses the lower androecium whorl slightly at the beginning, and markedly in further stages. Under the epidermis of an ovule, a multicellular archesporium is formed. Mitotic division of these cells gives rise to a two-layered parietal tissue and to a group of megaspore mother cells (MMCs). The tetrad is formed from one megasporocyte. In the bud development of <em>Pisum sativum</em> the carpel walls accrete to each other relatively early.

scholarly journals A small increase in CHEK1 activity leads to the arrest of the first zygotic division in human

2020 ◽  
Author(s):  
Beili Chen ◽  
Jianying Guo ◽  
Ting Wang ◽  
Qianhui Lee ◽  
Jia Ming ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Mitotic Checkpoint ◽  
Mitotic Division ◽  
Fine Tuning ◽  
Human Reproduction ◽  
Cycle Arrest ◽  
Assisted Human Reproduction ◽  
C Terminus ◽  
Low Concentrations

ABSTRACTThe first mitotic division in mammalian zygotes is unique. The fertilized egg reactivates its cell cycle, and the maternal and paternal genomes start to reprogram to become totipotent. The first division is very sensitive to a range of perturbations, particularly the DNA damage, leading to the embryo’s failure to enter the first mitosis. We discovered that a point mutation in the human CHEK1 gene resulted in an Arginine 442 to Glutamine change at the C-terminus of the CHEK1 protein. CHEK1 R442Q mutation caused the zygote to arrest just before the first division. Heterozygote individuals appeared to be healthy except that the female carriers are infertile. Expressing the corresponding mouse mutant Chk1 protein in zygotes also caused arrest before the first mitosis. Treating Chk1 R442Q mouse zygotes with low concentrations of CHEK1 inhibitor enabled the embryos to overcome the cell cycle arrest and resume normal development. Our results revealed an unexpected zygote mitotic checkpoint, which is extremely sensitive to the CHEK1 kinase activity. The fine-tuning of the DNA damage checkpoint permits the arrested one-cell embryos to overcome the first mitotic block and develop into healthy animals. These findings have important implications in assisted human reproduction.

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