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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 ...
URA3 is often used in yeast research as a "marker gene", that is, a gene to label chromosomes or plasmids. URA3 encodes Orotidine 5'-phosphate decarboxylase (ODCase), which is an enzyme that catalyzes one reaction in the synthesis of pyrimidine ribonucleotides (a component of RNA). [1]
In particular, if the distribution of survivor number turns out to decay more like a power law than like an exponential, then we can conclude with high statistical likelihood that Darwinian scenario is true. This is a rough overview of the Luria–Delbrück experiment. (Section 4.4 [1])
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]
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.
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 ...
Synthetic genetic array analysis is generally conducted using colony arrays on petriplates at standard densities (96, 384, 768, 1536). To perform a SGA analysis in S.cerevisiae, the query gene deletion is crossed systematically with a deletion mutant array (DMA) containing every viable knockout ORF of the yeast genome (currently 4786 strains). [9]
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.