Analysis of second-step mutations of class II and class III CHO aprt heterozygotes: chromosomal differences in deletion frequencies
| Autor: | Walter Edward Bradley, Abdelmajid Belouchi |
|---|---|
| Rok vydání: | 1991 |
| Předmět: |
Heterozygote
Genetic Linkage Fixed allele Molecular Sequence Data Adenine Phosphoribosyltransferase Biology medicine.disease_cause Polymerase Chain Reaction Cell Line Cricetulus Gene Frequency Cricetinae Genetics medicine Animals Allele Allele frequency Alleles Chromosomal inversion Mutation Base Sequence Ovary Wild type Cell Biology General Medicine Null allele Molecular biology Female Restriction fragment length polymorphism Chromosome Deletion Polymorphism Restriction Fragment Length |
| Zdroj: | Somatic cell and molecular genetics. 17(3) |
| ISSN: | 0740-7750 |
| Popis: | We have determined the nucleotide sequence surrounding a BclI restriction fragment length variation near the aprt gene of CHO cells. By BclI digestion of the PCR-amplified DNA from a variety of APRT-deficient mutants derived from CHO cells, we were able to infer the following. First, all three heterozygotes of class II, which are known to undergo the second mutational step via a large deletion event occurring at high frequency, are mutant at the chromosome Z4-linked allele, and wild type at the Z7 allele. Second, both class-III heterozygotes, which mutate to the APRT- phenotype at low frequency, are mutant at the Z7 allele, wild type at the Z4 allele. A total of 12 class-I lines, defined as having already undergone a deletion event and yielding fully APRT- mutants at low frequency were all found to have lost the Z7-linked allele. We conclude that the Z7-linked allele is substantially more susceptible to mutation by the large deletion event than is the Z4-linked allele. This supports a hypothesis we advanced earlier to explain the existence of the class-III heterozygotes but does not support previous work suggesting that a chromosomal inversion break-point junction near the Z4-linked aprt allele is responsible for the high frequency deletion event. |
| Databáze: | OpenAIRE |
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