Non-Mendelian inheritance induced by gene amplification in the germ nucleus of Paramecium tetraurelia.
A genetic investigation of strain d4-95, which carries a recessive mutant allele (pwB(95)) of pawn-B, one of the controlling elements of voltage-dependent calcium channels in Paramecium tetraurelia, revealed a non-Mendelian feature. Progeny of the cross between d4-95 and wild type often expressed a clonally stable mutant phenotype, even when they had a wild-type gene. The mutant phenotype was also expressed after self-fertilization of theoretical wild-type homozygotes recovered from the cross. Our molecular analysis demonstrated that the copy number of the mutant pwB gene in the micro- and macronucleus of d4-95 was much greater than that of the wild type. Most of the amplified, extra pwB gene copies in d4-95 were heritable independently from the original pwB locus. Repeated backcrossing of d4-95 with the wild type to dilute extra pwB genes in the strain produced segregants with a completely normal Mendelian trait in testcrosses. These results strongly suggest that a non-Mendelian inheritance of d4-95 was induced by gene amplification in the micronucleus.
Matsuda
Atsushi
A
Institute of Biological Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8572, Japan.
Takahashi
Mihoko
M
D000483:Alleles; D000818:Animals; D015220:Calcium Channels / Q000235:genetics; D002467:Cell Nucleus / Q000502:physiology*; D003433:Crosses, Genetic; D016054:DNA, Protozoan / Q000302:isolation & purification; D005306:Fertilization; D005784:Gene Amplification; D018628:Gene Dosage; D005808:Genes, Recessive; D006720:Homozygote; D008565:Membrane Proteins; D009154:Mutation; D016805:Paramecium tetraurelia / Q000235:genetics*; D010641:Phenotype; D015800:Protozoan Proteins
D015220:Calcium Channels; D016054:DNA, Protozoan; D008565:Membrane Proteins; D015800:Protozoan Proteins; C412164:pawn-B protein, Paramecium tetraurelia