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In genetics, a strain is said to be auxotrophic if it carries a mutation that renders it unable to synthesize an essential compound. For example, a yeast mutant with an inactivated uracil synthesis pathway gene is a uracil auxotroph (e.g., if the yeast Orotidine 5'-phosphate decarboxylase gene is inactivated, the resultant strain is a uracil ...
Auxotrophic selection markers that allow an auxotrophic organism to grow in minimal growth medium may also be used; examples of these are LEU2 and URA3 which are used with their corresponding auxotrophic strains of yeast. [7] Another kind of selectable marker allows for the positive selection of plasmid with cloned gene.
A selectable marker is a gene introduced into cells, especially bacteria or cells in culture, which confers one or more traits suitable for artificial selection.They are a type of reporter gene used in laboratory microbiology, molecular biology, and genetic engineering to indicate the success of a transfection or transformation or other procedure meant to introduce foreign DNA into a cell.
Next to the above-mentioned selection makers a few auxotrophic strains were generated to work with auxotrophic makers. The URA3 marker (URA3 blaster method) is an often-used strategy in uridine auxotrophic strains; however, studies have shown that differences in URA3 position in the genome can be involved in the pathogeny of C. albicans. [119]
Another method of selection is the use of certain auxotrophic markers that can compensate for an inability to metabolise certain amino acids, nucleotides, or sugars. This method requires the use of suitably mutated strains that are deficient in the synthesis or utility of a particular biomolecule, and the transformed cells are cultured in a ...
Yeast artificial chromosomes (YACs) are genetically engineered chromosomes derived from the DNA of the yeast, Saccharomyces cerevisiae, which is then ligated into a bacterial plasmid. By inserting large fragments of DNA, from 100–1000 kb, the inserted sequences can be cloned and physically mapped using a process called chromosome walking .
Mammalian cells, yeast, and other eukaryotes acquire resistance to geneticin (= G418, an aminoglycoside antibiotic similar to kanamycin) when transformed with a kanMX marker. In yeast, the kanMX marker avoids the requirement of auxotrophic markers. In addition, the kanMX marker renders E. coli resistant to kanamycin.
The permissive temperature is the temperature at which a temperature-sensitive mutant gene product takes on a normal, functional phenotype. [2] When a temperature-sensitive mutant is grown in a permissive condition, the mutant gene product behaves normally (meaning that the phenotype is not observed), even if there is a mutant allele present.