Pachytene

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Kuei-shu Tung - One of the best experts on this subject based on the ideXlab platform.

  • Nuclear localization of the meiosis-specific transcription factor Ndt80 is regulated by the Pachytene checkpoint.
    Molecular biology of the cell, 2011
    Co-Authors: Ying Wang, Chun-yu Chang, Kuei-shu Tung
    Abstract:

    In budding yeast, the Ndt80 protein is a meiosis-specific transcription factor that is essential for the exit of Pachytene and progression into nuclear divisions and spore formation. The Pachytene checkpoint responds to defects in meiotic recombination and chromosome synapsis and negatively regulates the activity of Ndt80. The activity of Ndt80 was suggested to be regulated at both transcriptional and posttranslational levels; however, the mechanism for posttranslational regulation of Ndt80 was unclear. From a study of ndt80 in-frame deletion mutations, we have identified a dominant mutation NDT80-bc, which is able to completely bypass the Pachytene checkpoint. The NDT80-bc mutation relieves the checkpoint-mediated arrest of the zip1, dmc1, and hop2 mutants, producing spores with low viability. The NDT80-bc mutant provides direct evidence for the posttranslational control of Ndt80 activity. Furthermore, the data presented show that Ndt80 is retained in cytoplasm in the zip1 mutant, whereas Ndt80-bc is found in the nucleus. We propose that the nuclear localization of Ndt80 is regulated by the Pachytene checkpoint through a cytoplasmic anchor mechanism.

  • The Pachytene checkpoint prevents accumulation and phosphorylation of the meiosis-specific transcription factor Ndt80
    Proceedings of the National Academy of Sciences of the United States of America, 2000
    Co-Authors: Kuei-shu Tung, Eun-jin Erica Hong, G. Shirleen Roeder
    Abstract:

    Abstract In budding yeast, many mutants defective in meiotic recombination and chromosome synapsis undergo checkpoint-mediated arrest at the Pachytene stage of meiotic prophase. We recovered the NDT80 gene in a screen for genes whose overexpression bypasses the Pachytene checkpoint. Ndt80 is a meiosis-specific transcription factor that promotes expression of genes required for exit from Pachytene and entry into meiosis I. Herein, we show that the Ndt80 protein accumulates and is extensively phosphorylated during meiosis in wild type but not in cells arrested at the Pachytene checkpoint. Our results indicate that inhibition of Ndt80 activity is one mechanism used to achieve Pachytene arrest.

G. Shirleen Roeder - One of the best experts on this subject based on the ideXlab platform.

  • The Pachytene checkpoint prevents accumulation and phosphorylation of the meiosis-specific transcription factor Ndt80
    Proceedings of the National Academy of Sciences of the United States of America, 2000
    Co-Authors: Kuei-shu Tung, Eun-jin Erica Hong, G. Shirleen Roeder
    Abstract:

    Abstract In budding yeast, many mutants defective in meiotic recombination and chromosome synapsis undergo checkpoint-mediated arrest at the Pachytene stage of meiotic prophase. We recovered the NDT80 gene in a screen for genes whose overexpression bypasses the Pachytene checkpoint. Ndt80 is a meiosis-specific transcription factor that promotes expression of genes required for exit from Pachytene and entry into meiosis I. Herein, we show that the Ndt80 protein accumulates and is extensively phosphorylated during meiosis in wild type but not in cells arrested at the Pachytene checkpoint. Our results indicate that inhibition of Ndt80 activity is one mechanism used to achieve Pachytene arrest.

  • Pachytene Exit Controlled by Reversal of Mek1-Dependent Phosphorylation
    Cell, 2000
    Co-Authors: Julie M Bailis, G. Shirleen Roeder
    Abstract:

    During yeast meiosis, a checkpoint prevents exit from Pachytene in response to defects in meiotic recombination and chromosome synapsis. This Pachytene checkpoint requires two meiotic chromosomal proteins, Red1 and Mek1; Mek1 is a kinase that phosphorylates Red1. In mutants that undergo checkpoint-mediated Pachytene arrest, Mek1 is active and Red1 remains phosphorylated. Activation of Mek1 requires the initiation of meiotic recombination and certain DNA damage checkpoint proteins. Mek1 kinase activity and checkpoint-induced Pachytene arrest are counteracted by protein phosphatase type 1 (Glc7). Glc7 coimmunoprecipitates with Red1, colocalizes with Red1 on chromosomes, and dephosphorylates Red1 in vitro. We speculate that phosphorylated Red1 prevents exit from Pachytene and that completion of meiotic recombination triggers Glc7-dependent dephosphorylation of Red1.

Jiming Jiang - One of the best experts on this subject based on the ideXlab platform.

  • Super-stretched Pachytene chromosomes for plant molecular cytogenetic mapping.
    Methods in molecular biology (Clifton N.J.), 2010
    Co-Authors: Dal-hoe Koo, Jiming Jiang
    Abstract:

    We developed a simple technique to mechanically stretch maize Pachytene chromosomes more than 20 times longer than their original size. A modified Carnoy's II solution (6:3:1) ethanol:acetic acid:chloroform was used to fix the meiotic sample. The super-stretched Pachytene chromosomes produced from this procedure can be directly used in conventional fluorescence in situ hybridization (FISH) experiments and also for the immunofluorescent in situ detection of DNA methylation. This technique adds a new dimension and higher resolving power to Pachytene chromosome-based molecular cytogenetics research.

  • super stretched Pachytene chromosomes for fluorescence in situ hybridization mapping and immunodetection of dna methylation
    Plant Journal, 2009
    Co-Authors: Dal-hoe Koo, Jiming Jiang
    Abstract:

    Meiotic Pachytene chromosome-based fluorescence in situ hybridization (FISH) mapping is one of the most important tools in plant molecular cytogenetic research. Here we report a simple technique that allows stretching of Pachytene chromosomes of maize to up to at least 20 times their original size. A modified Carnoy's II fixative (6:1:3 ethanol:chloroform:acetic acid) was used in the procedure, and proved to be key for super-stretching of Pachytene chromosomes. We demonstrate that super-stretched Pachytene chromosomes provide unprecedented resolution for chromosome-based FISH mapping. DNA probes separated by as little as 50 kb can be resolved on super-stretched chromosomes. A combination of FISH with immunofluorescent detection of 5-methyl cytosine on super-stretched Pachytene chromosomes provides a powerful tool to reveal DNA methylation of specific chromosomal domains, especially those associated with highly repetitive DNA sequences.

  • Super‐stretched Pachytene chromosomes for fluorescence in situ hybridization mapping and immunodetection of DNA methylation
    The Plant journal : for cell and molecular biology, 2009
    Co-Authors: Dal-hoe Koo, Jiming Jiang
    Abstract:

    Meiotic Pachytene chromosome-based fluorescence in situ hybridization (FISH) mapping is one of the most important tools in plant molecular cytogenetic research. Here we report a simple technique that allows stretching of Pachytene chromosomes of maize to up to at least 20 times their original size. A modified Carnoy's II fixative (6:1:3 ethanol:chloroform:acetic acid) was used in the procedure, and proved to be key for super-stretching of Pachytene chromosomes. We demonstrate that super-stretched Pachytene chromosomes provide unprecedented resolution for chromosome-based FISH mapping. DNA probes separated by as little as 50 kb can be resolved on super-stretched chromosomes. A combination of FISH with immunofluorescent detection of 5-methyl cytosine on super-stretched Pachytene chromosomes provides a powerful tool to reveal DNA methylation of specific chromosomal domains, especially those associated with highly repetitive DNA sequences.

  • construction of a bacterial artificial chromosome bac library for potato molecular cytogenetics research
    Genome, 2000
    Co-Authors: Junqi Song, Fenggao Dong, Jiming Jiang
    Abstract:

    Lack of reliable techniques for chromosome identification is the major obstacle for cytogenetics research in plant species with large numbers of small chromosomes. To promote molecular cytogenetics research of potato (Solanum tuberosum, 2n = 4x = 48) we developed a bacterial artificial chromosome (BAC) library of a diploid potato species S. bulbocastanum. The library consists of 23 808 clones with an average insert size of 155 kb, and represents approximately 3.7 equivalents to the potato genome. The majority of the clones in the BAC library generated distinct signals on specific potato chromosomes using fluorescence in situ hybridization (FISH). The hybridization signals provide excellent cytological markers to tag individual potato chromosomes. We also demonstrated that the BAC clones can be mapped to specific positions on meiotic Pachytene chromosomes. The excellent resolution of Pachytene FISH can be used to construct a physical map of potato by mapping molecular marker-targeted BAC clones on pachyten...

Ying Wang - One of the best experts on this subject based on the ideXlab platform.

  • Nuclear localization of the meiosis-specific transcription factor Ndt80 is regulated by the Pachytene checkpoint.
    Molecular biology of the cell, 2011
    Co-Authors: Ying Wang, Chun-yu Chang, Kuei-shu Tung
    Abstract:

    In budding yeast, the Ndt80 protein is a meiosis-specific transcription factor that is essential for the exit of Pachytene and progression into nuclear divisions and spore formation. The Pachytene checkpoint responds to defects in meiotic recombination and chromosome synapsis and negatively regulates the activity of Ndt80. The activity of Ndt80 was suggested to be regulated at both transcriptional and posttranslational levels; however, the mechanism for posttranslational regulation of Ndt80 was unclear. From a study of ndt80 in-frame deletion mutations, we have identified a dominant mutation NDT80-bc, which is able to completely bypass the Pachytene checkpoint. The NDT80-bc mutation relieves the checkpoint-mediated arrest of the zip1, dmc1, and hop2 mutants, producing spores with low viability. The NDT80-bc mutant provides direct evidence for the posttranslational control of Ndt80 activity. Furthermore, the data presented show that Ndt80 is retained in cytoplasm in the zip1 mutant, whereas Ndt80-bc is found in the nucleus. We propose that the nuclear localization of Ndt80 is regulated by the Pachytene checkpoint through a cytoplasmic anchor mechanism.

Zhiping Weng - One of the best experts on this subject based on the ideXlab platform.

  • long first exons and epigenetic marks distinguish conserved Pachytene pirna clusters from other mammalian genes
    Nature Communications, 2021
    Co-Authors: Phillip D Zamore, Zhiping Weng, Kaili Fan, Deniz M Ozata, Gen Zhang, William E Theurkauf
    Abstract:

    In the male germ cells of placental mammals, 26–30-nt-long PIWI-interacting RNAs (piRNAs) emerge when spermatocytes enter the Pachytene phase of meiosis. In mice, Pachytene piRNAs derive from ~100 discrete autosomal loci that produce canonical RNA polymerase II transcripts. These piRNA clusters bear 5′ caps and 3′ poly(A) tails, and often contain introns that are removed before nuclear export and processing into piRNAs. What marks Pachytene piRNA clusters to produce piRNAs, and what confines their expression to the germline? We report that an unusually long first exon (≥ 10 kb) or a long, unspliced transcript correlates with germline-specific transcription and piRNA production. Our integrative analysis of transcriptome, piRNA, and epigenome datasets across multiple species reveals that a long first exon is an evolutionarily conserved feature of Pachytene piRNA clusters. Furthermore, a highly methylated promoter, often containing a low or intermediate level of CG dinucleotides, correlates with germline expression and somatic silencing of Pachytene piRNA clusters. Pachytene piRNA precursor transcripts bind THOC1 and THOC2, THO complex subunits known to promote transcriptional elongation and mRNA nuclear export. Together, these features may explain why the major sources of Pachytene piRNA clusters specifically generate these unique small RNAs in the male germline of placental mammals. The Pachytene piRNA loci are transcribed by RNA polymerase II in the male germline of placental mammals. Here the authors show that a long first exon or a long unspliced transcript correlates with germline-specific production of piRNA precursor transcripts and mature piRNAs.

  • an ancient transcription factor initiates the burst of pirna production during early meiosis in mouse testes
    Molecular Cell, 2013
    Co-Authors: Xin Zhiguo Li, Zhiping Weng, Xianjun Dong, Ewelina Bolcunfilas, Jie Wang, Jia Xu, Melissa J Moore, John C Schimenti, Phillip D Zamore
    Abstract:

    Animal germ cells produce PIWI-interacting RNAs (piRNAs), small silencing RNAs that suppress transposons and enable gamete maturation. Mammalian transposon-silencing piRNAs accumulate early in spermatogenesis, whereas Pachytene piRNAs are produced later during postnatal spermatogenesis and account for >95% of all piRNAs in the adult mouse testis. Mutants defective for Pachytene piRNA pathway proteins fail to produce mature sperm, but neither the piRNA precursor transcripts nor the trigger for Pachytene piRNA production is known. Here, we show that the transcription factor A-MYB initiates Pachytene piRNA production. A-MYB drives transcription of both Pachytene piRNA precursor RNAs and the mRNAs for core piRNA biogenesis factors including MIWI, the protein through which Pachytene piRNAs function. A-MYB regulation of piRNA pathway proteins and piRNA genes creates a coherent feedforward loop that ensures the robust accumulation of Pachytene piRNAs. This regulatory circuit, which can be detected in rooster testes, likely predates the divergence of birds and mammals.