Analysis of Paramecium macronuclear DNA using pulsed field gel electrophoresis.
We have analyzed the macronuclear DNA of Paramecium tetraurelia using orthogonal-field-alternation gel electrophoresis. The mean size of the linear macronuclear DNA molecules is approximately 450 kb. Less than 6% of the macronuclear DNA is larger than 800 kb. Using pulse times of 20, 40, 60 and 90 s we show that the macronuclear fragment containing the A type variable surface antigen gene migrates reproducibly as a 320-kb linear DNA. Over the same pulse times we describe the unusual migration of the ribosomal RNA gene (rDNA) of P. tetraurelia. At pulse times of 20 and 40 s the rDNA migrates at limit mobility (300 and 500 kb, respectively) whereas with 60- and 90-s pulse times, 2 components of rDNA are observed; 1 fraction independent of pulse time migrating at limit mobility, and a 2nd component migrating between 100-kb and 400-kb linear markers. Based upon previous electron micrographic studies of Paramecium rDNA as well as data presented here we conclude that the majority of Paramecium rDNA molecules are a circular DNA form.
Phan
H L
HL
Department of Molecular Biology, University of California, Berkeley 94720.
Forney
J
J
Blackburn
E H
EH
D000818:Animals; D015139:Blotting, Southern; D004270:DNA, Circular / Q000032:analysis*; D004587:Electrophoresis, Agar Gel / Q000379:methods; D009690:Nucleic Acid Conformation; D009693:Nucleic Acid Hybridization; D010247:Paramecium / Q000235:genetics / Q000378:metabolism*; D012335:RNA, Ribosomal / Q000235:genetics
D004270:DNA, Circular; D012335:RNA, Ribosomal