Restoration Of Wild-type Phenotype Research Articles

Injection of total genomic DNA and restoration of wild type phenotype in trichocyst non-discharge mutant TND of Paramecium caudatum.

To restore wild type phenotypes in mutants controlled by recessive genes, microinjection of whole genomic DNA into recipient macronucleus in Paramecium caudatum was performed. Donor DNA carrying three wild-type genetic markers (exocytosis, behavior and mating type) was introduced into a recipient cell which was a triple recessive homozygote for the corresponding genes. Of the three phenotypes, a trichocyst non-discharge mutant TND converted to wild type by microinjection of not only total genomic DNA but also fractionated restriction fragments, although the restored phenotype was not complete. This transformation was more efficient when injection was performed by using the recipient cells of S phase, compared with the cells of G1 phase. This successful restoration of wild type phenotype gives us hope for cloning mutated genes, especially when no information about gene products is available. We discuss the advantage of this total genomic DNA injection and the possibility of target gene cloning using this strategy.

Injection of total genomic DNA and restoration of wild type phenotype in trichocyst non-discharge mutant TND of Paramecium caudatum

Injection of total genomic DNA and restoration of wild type phenotype in trichocyst non-discharge mutant TND of Paramecium caudatum

GENETIC MODULATION OF RNA METABOLISM IN DROSOPHILA. I. INCREASED RATE OF RIBOSOMAL RNA SYNTHESIS

ABSTRACT It has been suggested that a particular Y chromosome which is rDNA-deficient (YbbSuVar-5) may be associated with an increased utilization of rDNA template in adult testes (Shermoen and Kiefer 1975). To extend the observations on this chromosome, experiments were designed to determine if the chromosome has an effect on rRNA synthesis in bobbed adults and on classic bobbed phenotypes (shortened and thinner scutellar bristles and delayed development). Specific activity measurements were made on rRNA extracted from adult males of the genotypes car bb/Ybb- and car bb/YbbSuVar-5, which are rDNA-deficient to the same extent, and from Samarkand+ isogenic (Sam+ iso), which is a wild-type stock. The resulting data demonstrated that the presence of the YbbSuVar-5 chromosome increases the rate of ribosomal RNA synthesis in adult flies. In addition, it was found that the presence of this particular Y chromosome restores wild-type bristle phenotype and development time. Appropriate genetic crosses indicate that the observed effects (increased rRNA synthesis, restoration of wild-type phenotype) are a function of this particular Y chromosome, and are not due to autosomal factors. The results of these experiments suggest that the rate of rRNA accumulation is under genetic control.