Macronuclear transformation with specific DNA fragments controls the content of the new macronuclear genome in Paramecium tetraurelia.
A previously isolated mutant cell line called d48 contains a complete copy of the A surface antigen gene in the micronuclear genome, but the gene is not incorporated into the macronucleus. Previous experiments have shown that a cytoplasmic factor made in the wild-type macronucleus can rescue the mutant. Recently, S. Koizumi and S. Kobayashi (Mol. Cell. Biol. 9:4398-4401, 1989) observed that injection of a plasmid containing the A gene into the d48 macronucleus rescued the cell line after autogamy. It is shown here that an 8.8-kb EcoRI fragment containing only a portion of the A gene coding region is sufficient for the rescue of d48. The inability of other A gene fragments to rescue the mutant shows that this effect is dependent upon specific Paramecium DNA sequences. Rescue results in restoration of the wild-type DNA restriction pattern in the macronucleus. These results are consistent with a model in which the macronuclear A locus normally makes an additional gene product that is required for correct processing of the micronuclear copy of the A gene.
You
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Department of Biochemistry, Purdue University, West Lafayette, Indiana 47907.
Aufderheide
K
K
Morand
J
J
Rodkey
K
K
Forney
J
J
D000818:Animals; D000953:Antigens, Protozoan / Q000235:genetics*; D000954:Antigens, Surface / Q000235:genetics*; D015139:Blotting, Southern; D002467:Cell Nucleus / Q000502:physiology*; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics* / Q000302:isolation & purification; D008970:Molecular Weight; D009154:Mutation; D009693:Nucleic Acid Hybridization; D010247:Paramecium / Q000235:genetics / Q000276:immunology / Q000502:physiology*; D010957:Plasmids; D015183:Restriction Mapping
D000953:Antigens, Protozoan; D000954:Antigens, Surface; D004247:DNA