title: Metakaryotic stem cell nuclei use pangenomic dsRNA/DNA intermediates in genome replication and segregation.
abstract: Bell shaped nuclei of metakaryotic cells double their DNA content during and after symmetric and asymmetric amitotic fissions rather than in the separate, pre-mitotic S-phase of eukaryotic cells. A parsimonious hypothesis was tested that the two anti-parallel strands of each chromatid DNA helix were first segregated as ssDNA-containing complexes into sister nuclei then copied to recreate a dsDNA genome. Metakaryotic nuclei that were treated during amitosis with RNase A and stained with acridine orange or fluorescent antibody to ssDNA revealed large amounts of ssDNA. Without RNase treatment metakaryotic nuclei in amitosis stained strongly with an antibody complex specific to dsRNA/DNA. Images of amitotic figures co-stained with dsRNA/DNA antibody and DAPI indicated that the entire interphase dsDNA genome (B-form helices) was transformed into two dsRNA/DNA genomes (A-form helices) that were segregated in the daughter cell nuclei then retransformed into dsDNA. As this process segregates DNA strands of opposite polarity in sister cells it hypothetically offers a sequential switching mechanism within the diverging stem cell lineages of development.
authors.affiliation: Laboratory in Metakaryotic Biology; Department of Biological Engineering; Massachusetts Institute of Technology; Cambridge, MA USA.
authors.forename: William G
authors.initials: WG
authors.lastname: Thilly
authors.affiliation: Laboratory in Metakaryotic Biology; Department of Biological Engineering; Massachusetts Institute of Technology; Cambridge, MA USA.
authors.forename: Elena V
authors.initials: EV
authors.lastname: Gostjeva
authors.affiliation: Laboratory in Metakaryotic Biology; Department of Biological Engineering; Massachusetts Institute of Technology; Cambridge, MA USA.
authors.forename: Vera V
authors.initials: VV
authors.lastname: Koledova
authors.affiliation: Department of Pathology; Massachusetts General Hospital; Boston, MA USA.
authors.forename: Lawrence R
authors.initials: LR
authors.lastname: Zukerberg
authors.affiliation: Gastorointestinal Unit; Massachusetts General Hospital; Boston, MA USA.
authors.forename: Daniel
authors.initials: D
authors.lastname: Chung
authors.affiliation: Department of Toxicogenetics; Leiden University Medical Centre; Leiden, The Netherlands.
authors.forename: Janna N
authors.initials: JN
authors.lastname: Fomina
authors.affiliation: Department of Toxicogenetics; Leiden University Medical Centre; Leiden, The Netherlands.
authors.forename: Firouz
authors.initials: F
authors.lastname: Darroudi
authors.affiliation: Department of Developmental, Molecular and Chemical Biology; Tufts University School of Medicine; Boston, MA USA.
authors.forename: B David
authors.initials: BD
authors.lastname: Stollar
mesh_terms: D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000235:genetics*; D020090:Chromosome Segregation; D004247:DNA / Q000378:metabolism*; D004261:DNA Replication; D016650:Fluorescein-5-isothiocyanate / Q000737:chemistry; D016678:Genome; D006801:Humans; D007150:Immunohistochemistry; D059785:Karyotype; D012313:RNA / Q000378:metabolism*; D013234:Stem Cells / Q000166:cytology
chemical_list: D012313:RNA; D004247:DNA; D016650:Fluorescein-5-isothiocyanate
keywords: amitosis; development; differentiation; dsRNA/DNA; genome replication; metakaryotic; stem cells