ISSN:
1432-0983
Keywords:
Saccharomyces cerevisiae
;
Resistance
;
Mercury
;
Tyrosine
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Summary From a cross of two strains ofSaccharomyces cerevisiae, both of which had the same (wild type or normal) level of resistance to inorganic mercury, segregants having three distinguishable resistance levels, normal, sensitive and semi-sensitive, were obtained. Genetic analyses of the parents and the progeny indicated that the levels of inorganic mercury sensitivity were determined by three distinct loci,HGS1, HGS2 andMSM1. The recessive allele of theHGS1 locus,hgsl-1, and the codominant allele of theHGS2 locus,HGS2-1, were necessary for the sensitive phenotypes, and alleles in theMSM1 locus,MSMI-1 andmsml-2, were responsible for the different sensitivity levels. In short, the strains of genotypeshgs1-1 HGS2-1 msml-2 andhgsl-1 HGS2-1 MSMI-1 were sensitive and semi-sensitive, respectively, while the strains of all other genotypes were normal. Although thehgs1-1 allele was identified as thearo7-1 mutation which confers deficiency of tyrosine and phenylalanine, mutations such asaro1B (deficiency of tyrosine, phenylalanine and tryptophan) andtyr1 (deficiency of tyrosine) had similar effects asaro7-1 on inorganic mercury sensitivity. From these results we conclude that theHGS2-1 allele causes inorganic mercury sensitivity when the cells are defective in the tyrosine biosynthesis. In fact, addition of tyrosine to the growth medium containing inorganic mercury resulted in increase of colony forming ability of the sensitive strains.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00798747
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