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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
gal-
strains out there are either gal4, gal11 or gal3 (personal impression -
no
statistics). Conversely Gal+ means that the starin is (at least
marginally
utilize galactose) and has intact (more or less) Gal4p/Gal11p/Gal80/82p
system.

According to Ulery, Mangus and Jaehning (Mol Gen Genet 230: 129-135,
1991),
"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
inhibited.

Hope this helps.

Arle
*************************************************
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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