Birefringence and DNA condensation of liquid crystalline chromosomes.
DNA can self-assemble in vitro into several liquid crystalline phases at high concentrations. The largest known genomes are encoded by the cholesteric liquid crystalline chromosomes (LCCs) of the dinoflagellates, a diverse group of protists related to the malarial parasites. Very little is known about how the liquid crystalline packaging strategy is employed to organize these genomes, the largest among living eukaryotes-up to 80 times the size of the human genome. Comparative measurements using a semiautomatic polarizing microscope demonstrated that there is a large variation in the birefringence, an optical property of anisotropic materials, of the chromosomes from different dinoflagellate species, despite their apparently similar ultrastructural patterns of bands and arches. There is a large variation in the chromosomal arrangements in the nuclei and individual karyotypes. Our data suggest that both macroscopic and ultrastructural arrangements affect the apparent birefringence of the liquid crystalline chromosomes. Positive correlations are demonstrated for the first time between the level of absolute retardance and both the DNA content and the observed helical pitch measured from transmission electron microscopy (TEM) photomicrographs. Experiments that induced disassembly of the chromosomes revealed multiple orders of organization in the dinoflagellate chromosomes. With the low protein-to-DNA ratio, we propose that a highly regulated use of entropy-driven force must be involved in the assembly of these LCCs. Knowledge of the mechanism of packaging and arranging these largest known DNAs into different shapes and different formats in the nuclei would be of great value in the use of DNA as nanostructural material.
Chow
Man H
MH
Hong Kong University of Science and Technology, Kowloon, Hong Kong.
Yan
Kosmo T H
KT
Bennett
Michael J
MJ
Wong
Joseph T Y
JT
D000818:Animals; D001718:Birefringence; D002467:Cell Nucleus / Q000235:genetics; D002875:Chromosomes / Q000235:genetics / Q000648:ultrastructure*; D003460:Crystallization; D016054:DNA, Protozoan / Q000235:genetics / Q000648:ultrastructure*; D004141:Dinoflagellida / Q000235:genetics*; D050866:Liquid Crystals; D046529:Microscopy, Electron, Transmission; D008856:Microscopy, Fluorescence; D009690:Nucleic Acid Conformation
D016054:DNA, Protozoan
Biophys Chem. 1988 Feb;29(1-2):51-62
3282561
Proc Natl Acad Sci U S A. 2003 Dec 23;100(26):15294-8
14668440
Chromosoma. 1989 Oct;98(4):280-6
2612287
Biophys J. 1993 Jul;65(1):56-72
8369461
Science. 1972 May 19;176(4036):796-7
5031474
Ultramicroscopy. 1993 Feb;49(1-4):235-51
8475602
J Struct Biol. 2004 Jun;146(3):281-90
15099570
Nature. 1999 Jul 1;400(6739):83-5
10403254
Eur J Cell Biol. 1981 Feb;23(2):295-302
6258920
Chromosoma. 2005 Dec;114(6):420-31
16252092
Eur J Cell Biol. 1984 Mar;33(2):300-11
6538843
J Theor Biol. 1997 Oct 7;188(3):379-85
9344743
Arch Androl. 2000 Nov-Dec;45(3):215-25
11111870
J Cell Biol. 1982 May;93(2):298-305
7096440
Eur Biophys J. 2008 Jul;37(6):1059-64
18259740
FEMS Microbiol Lett. 1992 Dec 15;100(1-3):361-70
1478471
Can J Microbiol. 1962 Apr;8:229-39
13902807
Tissue Cell. 1984;16(4):535-55
6484936
Eukaryot Cell. 2003 Jun;2(3):646-50
12796310
EMBO J. 2001 Mar 1;20(5):1184-91
11230141
Bioessays. 2005 Jul;27(7):730-40
15954095
Chromosoma. 1968;24(3):251-87
5708267
Philos Trans A Math Phys Eng Sci. 2006 Oct 15;364(1847):2615-33
16973479
Biophys J. 2006 May 15;90(10):3712-21
16500976
Nucleic Acids Res. 2007;35(8):2573-83
17412706
J Cell Biol. 2009 Sep 21;186(6):825-34
19752020
Chromosoma. 1991 Sep;100(8):510-8
1764969
Mol Biol Cell. 1999 Jan;10(1):197-210
9880336
Annu Rev Biophys Biomol Struct. 1993;22:27-65
7688609
Biochimie. 2001 Feb;83(2):187-92
11278068
Chromosoma. 1978 Aug 21;68(1):45-58
567570
Biophys J. 1998 Jan;74(1):645-54
9449366
Biol Cell. 2004 Oct;96(8):595-601
15519694
FEBS Lett. 1996 Jul 29;390(3):245-8
8706869