title: Nuclear deoxyribonucleic acid characterization of the marine chromophyte Olisthodiscus luteus.
abstract: Nuclear DNA of the marine chromophytic alga Olisthodiscus luteus was analyzed in this study. Reassociation kinetics analysis has shown that 440-nucleotide DNA fragments from the genome of this alga contain 4% foldback, 58% repetitive, and 34% single-copy sequences. Precise analysis using isolated single-copy DNA revealed that Olisthodiscus has a large haploid DNA content of 1.66 x 10(-12) g/cell. For determination of the organization of single-copy and repetitive sequences within this genome, DNA fragments 3000 nucleotides in length were reassociated to C0t= 100 M . s. At this low C0t value 89% of the DNA bound to hydroxylapatite, suggesting that single-copy and repetitive elements are interspersed. The lengths of the duplexed repetitive DNA on these 3000-nucleotide fragments were measured by electron microscopy after digestion with S1 nuclease which removed the unreassociated single-copy DNA regions. Of these repetitive sequences, 68% were shorter than 1200 nucleotide pairs in length and had a modal length of 350 nucleotide pairs. A minor class of longer (to 4000 nucleotide pairs) repetitive sequences was also observed.
mesh_terms: D002467:Cell Nucleus / Q000032:analysis*; D004247:DNA / Q000032:analysis*; D004277:DNA, Single-Stranded / Q000032:analysis; D056890:Eukaryota / Q000032:analysis*; D005796:Genes; D007700:Kinetics; D008854:Microscopy, Electron; D009691:Nucleic Acid Denaturation; D009695:Nucleic Acid Renaturation; D012091:Repetitive Sequences, Nucleic Acid
chemical_list: D004277:DNA, Single-Stranded; D004247:DNA