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Meaning of GAL+ nomenclature

Arle Kruckeberg arle at biovax.leeds.ac.uk
Tue Nov 28 18:44:14 EST 1995

In article <30B37DE9.314F at medcor.mcgill.ca>
Greg Cosentino <Cosentino at medcor.mcgill.ca> writes:

> I have what will likely be a rather naive question. A yeast strain I 
> am using has the designation "GAL+" in the genotype description. I 
> can't find this described in either the Guthrie and Fink or 
> Strathern, Jones and Broach yeast handbooks [etc.]
To which Vlad (killer yeast) replies:
generally gal- means that the strain does not grow on galactose. Most
strains out there are either gal4, gal11 or gal3 (personal impression -
statistics). Conversely Gal+ means that the starin is (at least
utilize galactose) and has intact (more or less) Gal4p/Gal11p/Gal80/82p

According to Ulery, Mangus and Jaehning (Mol Gen Genet 230: 129-135,
"many laboratory strains of yeast are defective in galactose metabolism
owing to a recessive mutation in the previously characterized nuclear
gene  _IMP1_...we have shown that _IMP1_ and _GAL2_ [encoding the
galactose transporter] segregate as tightly linked genes. Based on
these data, we believe that _imp1_ is a partially defective allele of
the _GAL2_ gene". They go on to say that "S288C ... is known to carry a
defective _GAL2_ gene" and that "the Gal- phenotype [of the S288C
background] was reverted to Gal+ at an early point in the development
of these strains" but I do not know that this has ever been shown to be
"a correction in the _GAL2_ gene". Recently, I think in the journal
Yeast, strains were described for standard yeast molecular genetics in
which the defective _gal2_ allele was replaced with wildtype _GAL2_
allele (ref not at my fingertips). In my hands, _gal2_ strains grow on
galactose, but not well, and not well at all if respiration is

Hope this helps.

a.k.a. Dr. Arthur L. Kruckeberg
 Department of Biochemistry and Molecular Biology
University of Leeds        phone  +44 +113 2333172
Leeds LS2 9JT              FAX    +44 +113 2333167
Great Britain              arle at biovax.leeds.ac.uk

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