Directory 
Joan Ramon Daban Balaña
  • Biography
  • Professor Emeritus. Dept. of Biochemistry and Molecular Biology, UAB (2019-present)
    Professor. Dept. of Biochemistry and Molecular Biology, UAB (1999-2019)
    Associate Professor. Dept. of Biochemistry and Molecular Biology, UAB (1985-98)
    Assistant Professor. Dept. of Biochemistry, UAB (1981-84)
    Postdoc. Dept. of Chemistry, Columbia University, New York (1980-81)
    Postdoc. Institute of Fundamental Biology, UAB (1977-79)
    Ph.D. Institute of Fundamental Biology, UAB (1973-76)
    B.Sc. (Chemistry). University of Barcelona (1968-73)
    Technical Engineering (Chemistry). Escola Industrial, Barcelona (1963-68)
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  • Research groups
  • Chromatin Laboratory
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  • Projects
  • Our group was interested in the study of chromatin structure at intermediate concentrations of divalent cations. Our results led us to the proposal of the interdigitated solenoid model for the 30-nm fiber, which is now widely accepted in the chromatin literature. Since the early 2000s, we have been interested in the chromatin structure in the presence of higher cation concentrations, similar to those found in metaphase chromosomes. We have discovered that in condensed chromosomes, chromatin is densely packed forming plate-like structures instead of the typical fibers considered in the current models of metaphase chromosomes. Our electron microscopy images have shown that chromosome plates can form multilayered structures, having a thickness of approximately 6 nm each layer. These observations and further structural studies performed using atomic force microscopy have allowed us to suggest the thin-plate model for chromatin folding in metaphase chromosomes, in which we proposed that chromosomes are formed by many stacked plates oriented perpendicular to the chromatid axis. This model allows an easy physical explanation of the characteristic banding patterns of metaphase chromosomes obtained in cytogenetic studies. We have also found using electron tomography and polarizing microscopy that nucleosomes are irregularly oriented in the well-defined plates that occupy the entire volume of the chromatid. To justify the small thickness observed for the plates, we have suggested that there is an interdigitation between the successive layers. The resulting compact structure is necessary for the safe transfer of the genomic DNA to the daughter cells during mitosis. More recently, we have used synchrotron X-ray scattering techniques and cryo-electron tomography to study the internal structure and the physical properties of chromatin plates. At present, we are conducting theoretical and modeling studies on the possible biological functions of the multilaminar self-organization of chromosomes.
     
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  • Publications
  • - JR. Daban & A. Bermúdez (1998) Interdigitated solenoid model for compact chromatin fibers. Biochemistry 37:4299-4304
    - JR. Daban (2000) Physical constraints in the condensation of eukaryotic chromosomes. Local concentration of DNA versus lineal packing ratio in higher order chromatin structures. Bochemistry 39:3861-3866.
    - JR. Daban (2003) High concentration of DNA in condensed chromatin. Biochem. Cell Biol. 81:91-99.
    - JM. Caravaca, S. Caño, I. Gállego & JR. Daban (2005) Structural elements of bulk chromatin within metaphase chromosomes, Chromosome Res 13:725-743.
    - I. Gállego, P. Castro-Hartmann , JM Caravaca, S. Caño & J.R. Daban (2009) Dense chromatin plates in metaphase chromosomes. Eur Biophys J 38:503-522.
    - P. Castro-Hartmann, M. Milla  & JR. Daban (2010) Irregular orientation of nucleosomes in the well-defined chromatin plates of metaphase chromosomes. Biochemistry 49: 4043-4050.
    - I. Gállego, G. Oncins, X. Sisquella, X. Fernández-Busquets & JR. Daban (2010) Nanotribology results show that DNA forms a mechanically resistant 2D network in metaphase chromatin plates. Biophys J 99:3951-3958.
    - JR. Daban (2011) Electron microscopy and atomic force microscopy studies of chromatin and metaphase chromosome structure. Micron 42:733-750.
    - M. Milla & JR. Daban (2012) Self-assembly of thin plates from micrococcal nuclease-digested chromatin of metaphase chromosomes. Biophys J 103:567-575.
    - JR. Daban (2014) The energy components of stacked chromatin layers explain the morphology, dimensions and mechanical properties of metaphase chromosomes. J Royal Soc Interface 11: 20131043.
    - JR. Daban (2015) Stacked thin layers of metaphase chromatin explain the geometry of chromosome rearrangements and banding. Scientific Reports 5:14891.
    - A. Chicano,  E. Crosas,  J. Otón,  R. Melero, BD. Engel & JR. Daban (2019) Frozen-hydrated chromatin from metaphase chromosomes has an interdigitated multilayer structure.
    EMBO J. 38:e99769.
    - A. Chicano & JR. Daban (2019) Chromatin plates in the interphase nucleus. FEBS Lett. 593:810-819.
    - JR. Daban (2020) Supramolecular multilayer organization of chromosomes: possible functional roles of planar chromatin in gene expression and DNA replication and repair. FEBS Lett. 594:395-411.
    - JR. Daban (2021) Multilayer organization of chromosomes. In Cytogenomics (Editor: T. Liehr), Academic Press (Elsevier).
    - JR. Daban (2021) Soft-matter properties of multilayer chromosomes. Physical Biology, 18:053001.
     
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