DNA is able to condense into several orderly liquid crystalline mesophases at high concentrations both in vitro and in vivo. In the eukaryotic nucleosomeless dinoflagellates, liquid crystalline chromosomes have become the solution to condense its massive amount of DNA. In vivo chromosomes studies using the Metripol system, a motorized polarizer and data analyzer, have demonstrated that these specialized chromosomes have a defined karyology and are maintained in a highly spatially coordinated manner within the nucleus. Different karyology is observed among the species and surprisingly, not all dinoflagellates show birefringent properties in their chromosomes even though all of them apparently have same cholesteric texture in TEM sections. Several correlations are made against the retarda...[ Read more ]

DNA is able to condense into several orderly liquid crystalline mesophases at high concentrations both in vitro and in vivo. In the eukaryotic nucleosomeless dinoflagellates, liquid crystalline chromosomes have become the solution to condense its massive amount of DNA. In vivo chromosomes studies using the Metripol system, a motorized polarizer and data analyzer, have demonstrated that these specialized chromosomes have a defined karyology and are maintained in a highly spatially coordinated manner within the nucleus. Different karyology is observed among the species and surprisingly, not all dinoflagellates show birefringent properties in their chromosomes even though all of them apparently have same cholesteric texture in TEM sections. Several correlations are made against the retardance, which is a relative measure of the birefringence, of the chromosomes among various dinoflagellate species. These correlations suggest that the retardance, and probably the appearance of birefringence, is dependent on DNA content, DNA density and chromosomal organisations of the chromosomes. The current studies moreover implicate a new model to the structure of the dinoflagellate chromosomes. On the other hand, these specialised permanently condensed chromosomes have to devise a novel type of chromosomal proteins to maintain such a structure. Condensin, a multi-subunit protein that plays a central role in chromosome assembly and segregation in the prokaryotes and eukaryotes, is one of the potential protein candidates in maintaining the liquid crystalline genome. A putative condensin subunit, dCAP-H, is examined, and the results suggest that the dinoflagellates may possess a new type of condensin complex which function in the liquid crystalline genome.