title: Denaturation map of the ribosomal DNA of Lytechinus variegatus sperm.
abstract: Electron microscopy of the partially heat denatured ribosomal DNA (rDNA) from sea urchin (Lytechinus variegatus) sperm has demonstrated that it consists of repeating units of 3.6 +/- 0.2 micron, corresponding to a mol.wt of 7.2 +/- 0.4 x 10(6). Based on differential denaturability, each repeat unit is divided into 2 regions. The larger region of 2.47 +/- 0.11 micron (mol.wt 4.9 +/- 0.22 x 10(6)) corresponds in length to the ribosomal precursor RNA of sea urchins and the smaller, GC-rich, subunit of 1.16 +/- 0.09 micrometer (mol.wt 2.3 +/- 0.18 x 10(6)) is presumed to contain non-transcribed spacer sequences.
mesh_terms: D000818:Animals; D001483:Base Sequence; D004247:DNA; D008297:Male; D008854:Microscopy, Electron; D008970:Molecular Weight; D009691:Nucleic Acid Denaturation; D012270:Ribosomes / Q000032:analysis; D012617:Sea Urchins; D013094:Spermatozoa / Q000032:analysis*
chemical_list: D004247:DNA