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mitosis , meiosis

Arunika Das, Jeffry Cesario, Anna Maria Hinman, Janet K Jang, Kim S McKim
Bipolar spindle assembly occurs in the absence of centrosomes in the oocytes of most organisms. In the absence of centrosomes in Drosophila oocytes, we have proposed that the kinesin 6 Subito, a MKLP-2 homolog, is required for establishing spindle bipolarity and chromosome biorientation by assembling a robust central spindle during prometaphase I. Although the functions of the conserved motor domains of kinesins is well studied, less is known about the contribution of the poorly conserved N- and C- terminal domains to motor function...
March 7, 2018: G3: Genes—Genomes—Genetics
Michael D Griswold, Cathryn Hogarth
The first step in established spermatogenesis is the production of progenitor cells by the stem cell population. The progenitor cells (undifferentiated A spermatogonia) expand in number via the formation of syncytial chains by mitosis. The mechanism by which these progenitor cells commit to meiosis and spermatogenesis is tightly controlled and results in complex morphological organization all of which is designed to efficiently achieve large numbers of spermatozoa. The major extrinsic factor that triggers the commitment to meiosis and establishes the structural complexity is retinoic acid (RA)...
January 31, 2018: Stem Cell Research
Heike Loeser, Simon Schallenberg, Moritz von Winterfeld, Lars Tharun, Hakan Alakus, Arnulf Hölscher, Elfriede Bollschweiler, Reinhard Buettner, Thomas Zander, Alexander Quaas
Background: Esophageal adenocarcinomas show an increasing incidence in the Western world and their overall survival remains low. Microtubules are multifunctional cytoskeletal proteins involved in crucial cellular roles, including maintenance of cell shape, intracellular transport, meiosis, and mitosis. Microtubulus-TUBB3 was found overexpressed in several carcinomas suggesting a significant role in cancer development. High levels of TUBB3 expression were also described to be associated with poor clinical outcome in various cancers...
December 29, 2017: Oncotarget
Yu Ren, Feiyang Diao, Sunita Katari, Svetlana Yatsenko, Huaiyang Jiang, Michelle A Wood-Trageser, Aleksandar Rajkovic
BACKGROUND: Hypergonadotropic hypogonadism (HH) is a genetically heterogeneous disorder that usually presents with amenorrhea, atrophic ovaries, and low estrogen. Most cases of HH are idiopathic and nonsyndromic. Nucleoporin 107 (NUP107), a protein involved in transport between cytoplasm and nucleus with putative roles in meiosis/mitosis progression, was recently implicated as a cause of HH. We identified a NUP107 genetic variant in a nonconsanguineous family with two sisters affected with primary amenorrhea and HH, and generated a mouse model that carried the human variant...
January 24, 2018: Molecular Genetics & Genomic Medicine
Lijuan Feng, Zhen Shi, Jing Xie, Binbin Ma, Xin Chen
Tissue homeostasis depends on the ability of tissue-specific adult stem cells to maintain a balance between proliferation and differentiation, as well as ensure DNA damage repair. Here, we use the Drosophila male germline stem cell system to study how a chromatin factor, enhancer of polycomb [E(Pc)], regulates the proliferation-to-differentiation (mitosis-to-meiosis) transition and DNA damage repair. We identified two critical targets of E(Pc). First, E(Pc) represses CycB transcription, likely through modulating H4 acetylation...
January 23, 2018: Cell Death and Differentiation
Xing Duan, Yu Zhang, Kun-Lin Chen, Hao-Lin Zhang, Lan-Lan Wu, Hong-Lin Liu, Zhen-Bo Wang, Shao-Chen Sun
LIM kinases (LIMK1/2) are LIM domain-containing serine/threonine/tyrosine kinases that mediate multiple cellular processes in mitosis. In the present study, we explored the functional roles and potential signaling pathway of LIMK1/2 during mouse oocyte meiosis. Disruption of LIMK1/2 activity and expression significantly decreased oocyte polar body extrusion. Live-cell imaging revealed that spindle migration was disturbed after both LIMK1 and LIMK2 knock down, and this might be due to aberrant distribution of actin filaments in the oocyte cytoplasm and cortex...
January 10, 2018: Journal of Cellular Physiology
Tanvi Bhola, Orsolya Kapuy, P K Vinod
In response to developmental and environmental conditions, cells exit the mitotic cell cycle and enter the meiosis program to generate haploid gametes from diploid germ cells. Once cells decide to enter the meiosis program they become irreversibly committed to the completion of meiosis irrespective of the presence of cue signals. How meiotic entry and commitment occur due to the dynamics of the regulatory network is not well understood. Therefore, we constructed a mathematical model of the regulatory network that controls the transition from mitosis to meiosis in Schizosaccharomyces pombe...
January 9, 2018: Scientific Reports
Kouhei Takenaka, Takuma Tanabe, Makoto Kawamukai, Yasuhiro Matsuo
In Schizosaccharomyces pombe, the transcription factor Rst2 regulates ste11 in meiosis and fbp1 in glucogenesis downstream of the cyclic adenosine monophosphate (cAMP)-dependent protein kinase (PKA) pathway. Here, we demonstrate that Rst2 regulates additional cellular events. Overexpressed Rst2 elevated the frequency of oval, bent, branched, septated, and multi-septated cells. Cells showed normal nuclear divisions but exhibited abnormal nuclear organization at low frequency. In oval cells, microtubules were curved but they were rescued by the deletion of mal3...
January 10, 2018: Bioscience, Biotechnology, and Biochemistry
Paul Talbert, Sivakanthan Kasinathan, Steven Henikoff
Centromeres are the chromosomal sites of assembly for kinetochores, the protein complexes that attach to spindle fibers and mediate separation of chromosomes to daughter cells in mitosis and meiosis. In most multicellular organisms, centromeres comprise a single specific family of tandem repeats, often 100-400 bp in length, found on every chromosome, typically in one location within heterochromatin. Drosophila melanogaster is unusual in that the heterochromatin contains many families of mostly short (5-12 bp) tandem repeats, none of which appear to be present at all centromeres, and none of which are found only at centromeres...
January 5, 2018: Genetics
Qing Li, Hongdan Yang, Lin He, Qun Wang
Spermatogenesis involves a series of process including exiting from the mitotic cell cycle, entry into meiosis, completion of complex differentiation programs, and producing spermatozoa. Expression of various genes in an ordered manner, and interactions between various genes and their protein products, primarily controlled at the post-transcriptional level with DEAD-box RNA helicases playing a crucial role in germ cell development, are required for production of fertile sperm. Many members of this family have been deeply studied in spermatogenesis, such as DDX3X, DDX25 and DDX4, but few data are available on DDX52...
December 27, 2017: Gene
Joni M Seeling, Alexis A Farmer, Adam Mansfield, Hyuk Cho, Madhusudan Choudhary
Aurora kinases (AKs) are serine/threonine kinases that are essential for cell division. Humans have three AK genes: AKA, AKB, and AKC. AKA is required for centrosome assembly, centrosome separation, and bipolar spindle assembly, and its mutation leads to abnormal spindle morphology. AKB is required for the spindle checkpoint and proper cytokinesis, and mutations cause chromosome misalignment and cytokinesis failure. AKC is expressed in germ cells, and has a role in meiosis analogous to that of AKB in mitosis...
December 28, 2017: International Journal of Molecular Sciences
Antoine Vallot, Ioanna Leontiou, Damien Cladière, Warif El Yakoubi, Susanne Bolte, Eulalie Buffin, Katja Wassmann
Cell division with partitioning of the genetic material should take place only when paired chromosomes named bivalents (meiosis I) or sister chromatids (mitosis and meiosis II) are correctly attached to the bipolar spindle in a tension-generating manner. For this to happen, the spindle assembly checkpoint (SAC) checks whether unattached kinetochores are present, in which case anaphase onset is delayed to permit further establishment of attachments. Additionally, microtubules are stabilized when they are attached and under tension...
December 16, 2017: Current Biology: CB
Chencheng Yao, Qingqing Yuan, Minghui Niu, Hongyong Fu, Fan Zhou, Wenhui Zhang, Hong Wang, Liping Wen, Ligang Wu, Zheng Li, Zuping He
Human spermatogenesis includes three main stages, namely, the mitosis of spermatogonia, meiosis of spermatocytes, and spermiogenesis of spermatids, which are precisely regulated by epigenetic and genetic factors. Abnormality of epigenetic and genetic factors can result in aberrant spermatogenesis and eventual male infertility. However, epigenetic regulators in controlling each stage of normal and abnormal human spermatogenesis remain unknown. Here, we have revealed for the first time the distinct microRNA profiles in human spermatogonia, pachytene spermatocytes, and round spermatids between obstructive azoospermia (OA) patients and non-obstructive azoospermia (NOA) patients...
December 15, 2017: Molecular Therapy. Nucleic Acids
Fakhroddin Mesbah, Aris Donic Pracha, Tahereh Talaei-Khozani, Soghra Bahmanpour
Objective: The role of growth factors, including vascular endothelial growth factor of activated omentum on mitosis is clearly known, though not on all the aspects of in vitro oocyte maturation. This study was designed to assess the effect of activated-omental extract (AOE) on in vitro maturation (IVM) of rat cumulus-oocyte complexes (COCs). Materials and Methods: In this experimental study, the COCs were incubated in Ham's F-10 supplemented with either 20% AOE, 20% fetal bovine serum (FBS) or serum-free media...
December 2017: Iranian Journal of Basic Medical Sciences
Rachel Howard-Till, Josef Loidl
Condensin is a protein complex with diverse functions in chromatin packaging and chromosome condensation and segregation. We studied condensin in the evolutionarily distant protist model Tetrahymena, which features non-canonical nuclear organization and divisions. In Tetrahymena, the germline and soma are partitioned into two different nuclei within a single cell. Consistent with their functional specializations in sexual reproduction and gene expression, condensins of the germline nucleus and the polyploid somatic nucleus are composed of different subunits...
December 13, 2017: Molecular Biology of the Cell
Ernest G Heimsath, Yang-In Yim, Mirna Mustapha, John A Hammer, Richard E Cheney
Myosin-X (Myo10) is an unconventional myosin best known for its striking localization to the tips of filopodia. Despite the broad expression of Myo10 in vertebrate tissues, its functions at the organismal level remain largely unknown. We report here the generation of KO-first (Myo10tm1a/tm1a ), floxed (Myo10tm1c/tm1c ), and KO mice (Myo10tm1d/tm1d ). Complete knockout of Myo10 is semi-lethal, with over half of homozygous KO embryos exhibiting exencephaly, a severe defect in neural tube closure. All Myo10 KO mice that survive birth exhibit a white belly spot, all have persistent fetal vasculature in the eye, and ~50% have webbed digits...
December 11, 2017: Scientific Reports
Raquel Chamorro-Garcia, Carlos Diaz-Castillo, Bassem M Shoucri, Heidi Käch, Ron Leavitt, Toshi Shioda, Bruce Blumberg
Ancestral environmental exposures to non-mutagenic agents can exert effects in unexposed descendants. This transgenerational inheritance has significant implications for understanding disease etiology. Here we show that exposure of F0 mice to the obesogen tributyltin (TBT) throughout pregnancy and lactation predisposes unexposed F4 male descendants to obesity when dietary fat is increased. Analyses of body fat, plasma hormone levels, and visceral white adipose tissue DNA methylome and transcriptome collectively indicate that the F4 obesity is consistent with a leptin resistant, thrifty phenotype...
December 8, 2017: Nature Communications
Seira Miyazaki, Jihye Kim, Takeshi Sakuno, Yoshinori Watanabe
The kinetochore is the key apparatus regulating chromosome segregation. Particularly in meiosis, unlike in mitosis, sister kinetochores are captured by microtubules emanating from the same spindle pole (mono-orientation), and sister chromatid cohesion mediated by cohesin is protected at centromeres in the following anaphase. Shugoshin, which localizes to centromeres depending on the phosphorylation of histone H2A by Bub1 kinase, plays a central role in protecting meiotic cohesin Rec8 from separase cleavage...
December 1, 2017: Cold Spring Harbor Symposia on Quantitative Biology
Ting-Lu Yuan, Wei-Jie Huang, Juan He, Dong Zhang, Wei-Hua Tang
In flowering plants, germ lines are induced from somatic meristems within reproductive organs. Within anthers, germinal cell initials first undergo several rounds of mitotic proliferation before synchronously entering meiosis. Our understanding of the progression and the molecular basis of this mitosis to meiosis transition is still limited. Taking advantage of the correlation between anther length and premeiotic germinal cell development in maize ( Zea mays ), we studied the transcriptome dynamics of germinal cells at three sequential stages, mitotic archesporial cells, enlarging pollen mother cells at the premeiosis interphase, and pollen mother cells at the early prophase of meiosis, using laser microdissection-based expression profiling...
February 2018: Plant Physiology
Chao Shen, Ximei Li, Ruiting Zhang, Zhongxu Lin
Recombination is crucial for genetic evolution, which not only provides new allele combinations but also influences the biological evolution and efficacy of natural selection. However, recombination variation is not well understood outside of the complex species' genomes, and it is particularly unclear in Gossypium. Cotton is the most important natural fibre crop and the second largest oil-seed crop. Here, we found that the genetic and physical maps distances did not have a simple linear relationship. Recombination rates were unevenly distributed throughout the cotton genome, which showed marked changes along the chromosome lengths and recombination was completely suppressed in the centromeric regions...
2017: PloS One
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