A5078718906- Reproductive Biology and Fertility
- Microtubule and mitosis dynamics
- Genomics and Chromatin Dynamics
- DNA Repair Mechanisms
- Sperm and Testicular Function
- Animal Genetics and Reproduction
- RNA Research and Splicing
- Nuclear Structure and Function
- RNA Interference and Gene Delivery
- Epigenetics and DNA Methylation
- Chromosomal and Genetic Variations
- Lipid Membrane Structure and Behavior
- Pluripotent Stem Cells Research
- Cellular Mechanics and Interactions
- Ubiquitin and proteasome pathways
- Renal and related cancers
- DNA and Nucleic Acid Chemistry
- Magnetic confinement fusion research
- Reproductive biology and impacts on aquatic species
- Genetic and Clinical Aspects of Sex Determination and Chromosomal Abnormalities
- Plant Molecular Biology Research
- Telomeres, Telomerase, and Senescence
- Genetics, Aging, and Longevity in Model Organisms
- Cancer-related Molecular Pathways
- Protein Interaction Studies and Fluorescence Analysis
Nagoya University
2002-2020
Tokyo Institute of Technology
1995-2007
University of Wisconsin–Madison
2006
Northeast Agricultural University
2006
Ludwig-Maximilians-Universität München
2006
National Institute of Genetics
2005
Osaka University
2005
Nagasaki University
2005
University of California, San Diego
2001
Tokyo Metropolitan Institute of Medical Science
2000
Packaging without nucleosomes The fundamental compaction of DNA in chromosomes is thought to start with the wrapping around nucleosomes, but nucleosome required for condensation mitotic chromosomes? Shintomi et al. combined Xenopus egg extracts and mouse sperm nuclei found that chromosome-like structures could be assembled near-complete absence (see Perspective by Kakui Uhlmann). These “nucleosome-depleted” were composed condensin-enriched discrete axes poorly organized chromatin loops. This...
The contribution of histone H1 to mitotic chromosome condensation was examined with the use a cell-free extract from Xenopus eggs, which transforms condensed sperm nuclei into metaphase chromosomes. When removed extract, resultant chromosomes were indistinguishable those formed in complete extract. Nucleosomal spacing same for both. Thus, is not required structural reorganization that leads this egg
Complex transitions in chromatin structure produce changes genome function during development metazoa. Linker histones, the last component of nucleosomes to be assembled into chromatin, comprise considerably divergent subtypes as compared with core histones. In all metazoa studied, their composition dramatically early embryogenesis concomitant zygotic gene activation, leading distinct functional that are still poorly understood. Here, we show embryonic linker histone B4, which is maternally...
In eukaryotic cells, genomic DNA is primarily packaged into nucleosomes through sequential ordered binding of the core and linker histone proteins. The acidic proteins termed chaperones are known to bind histones neutralize their positive charges, thereby facilitating proper deposition onto assemble nucleosomes. For histones, however, little has been about regulatory mechanism for DNA. Here we report that, in Xenopus eggs, associated with homologue nucleosome assembly protein-1 (NAP-1),...
Abstract It is known that differentiated cells can be reprogrammed to an undifferentiated state in oocyte cytoplasm after nuclear transfer. Recently, some reports suggested Xenopus egg extracts have the ability reprogram mammalian somatic cells. Reprogramming events of extract treatment and cell culture extract‐treated not been elucidated. In this experiment, we examined reprogramming reversibly permeabilized or nonpermeabilized porcine fibroblast treatment. The egg‐specific histone B4 was...
Chromosome condensation is critical for accurate inheritance of genetic information. The degree condensation, which reflected in the size condensed chromosomes during mitosis, not constant. It differentially regulated embryonic and somatic cells. In addition to developmentally programmed regulation chromosome there may be adaptive based on spatial parameters such as genomic length or cell size. We propose that affected by a parameter called amount per nuclear space, “intranuclear DNA...
Nuclear transfer to oocytes is an efficient way transcriptionally reprogram somatic nuclei, but its mechanisms remain unclear. Here, we identify a sequence of molecular events that leads rapid transcriptional reprogramming nuclei after transplantation Xenopus oocytes. RNA-seq analyses reveal by results in selective switch transcription toward oocyte rather than pluripotent type, without requiring new protein synthesis. Time-course at the single-nucleus level show induced most transplanted...
Inactivation of cyclin B–Cdc2 kinase at the exit from M phase depends on specific proteolysis B subunit, whereas Cdc2 subunit remains present nearly constant levels throughout cell cycle. It is unknown how escapes degradation when destroyed. In Xenopus egg extracts that reproduce in vitro, we have found dissociation complex occurred under conditions where was tethered to 26S proteasome but not yet degraded. The dephosphorylation Thr 161 unlikely be necessary for two subunits. However,...
ABSTRACT Meiotic cell cycles differ from mitotic in that the former lack S-phase interphase between meiosis I and II. To obtain clues for mechanisms involved cycle regulation unique to meiosis, we have examined changes chromosomal morphology H1 kinase activity during a meiotic period metaphase (MI) II (MII) Xenopus oocytes. Using populations of oocytes underwent germinal vesicle breakdown (GVBD) within 10 minute interval, found declined gradually 60 after GVBD then increased steadily...
The ability to reprogram in vivo a somatic cell after differentiation is quite limited. One of the most impressive examples such process transdifferentiation pigmented epithelial cells (PECs) lens during regeneration newts. However, very little known molecular events that allow newt transdifferentiate. Histone B4 an oocyte-type linker histone replaces somatictype H1 reprogramming mediated by nuclear transfer (SCNT). We found expressed and required PECs. Knocking down decreased proliferation...
The Xenopus oocyte is known to accumulate filamentous or F‐actin in the nucleus, but it currently unknown whether also accumulates embryo nuclei. Using fluorescence‐labeled actin reporters, we examined distribution embryonic cells and found that nuclei during blastula stage not gastrula stage. To further investigate nuclear F‐actin, devised a egg extract reproduces formation of which accumulates. this extract, primarily at subnuclear membranous region essential maintain chromatin binding...
Oocytes of most vertebrates arrest at metaphase the second meiosis (meta-II) to await fertilization, thus preventing parthenogenetic activation. This is caused by a cytoplasmic activity called cytostatic factor (CSF), which was first identified in frog Rana pipiens oocyte >30 years ago. CSF executed maintaining cyclin B-Cdc2 elevated levels largely through prevention B destruction. Although established Mos-mitogen-activated protein kinase pathway and released Ca-calmodulin II pathway, it...
Abstract Human spermatozoa were demembranated with Triton X‐100 (TX) and injected into the mature eggs of Xenopus laevis . The nuclei these decondensed developed pronuclei. Chromosomes did not appear in until end a 5‐hr incubation period. When human further treated dithiothreitol (DTT) before they eggs, sperm nuclear decondensation pronuclear development took place considerably faster than detergent alone. By period, chromatin threads or chromosome‐like structures appeared, but none cleaved....
Recombination in a helium and helium-hydrogen plasma was experimentally investigated the linear divertor simulator NAGDIS-II. To identify physical mechanisms, electron-ion recombination (EIR) molecular assisted (MAR), parameters recombining region have been measured. We used spectroscopic techniques on basis of continuum emission line from highly excited levels due to EIR Langmuir probes. The dependence neutral pressure pure mixture shows clearly that is caused by different processes two...
Abstract Using dephosphorylated neurofilament (NF) proteins as substrates, the kinase with a higher activity for in NF‐H than phosphorylated form of was searched porcine brain extract. Most extract pelleted microtubules. The purified from high salt microtubule pellets composed cdk5 and 26 kDa protein, fragment 35 regulatory subunit cdk5. In contrast to association active microtubules, each uncomplexed differently distributed supernatant fraction pellet, respectively, by ultracentrifugation...
Abstract The conditions necessary for inducing pronucleus formation and chromosome condensation of human sperm nuclei were studied using Xenopus egg extracts. When lysolecithin (LC)‐and dithiothreitol (DTT)‐treated spermatozoa incubated with extract prepared an extraction medium containing 10 mM EGTA, transformed into chromosomes, bypassing the pronuclear stage. On contrary, LC‐DTT‐treated in without EGTA mimicked LC‐permeabilized that they underwent accompanied by DNA synthesis subsequent...