25

LEDERBERG, ESTHER H., University of Wisconsin, Madison,
WigoPisiotrony for maltese fermentetion and phage resis~
tence Int Scheriehia coll K-12.-=-iwo Loci, Maly eat Tp0>
aye been indepsndently described, Mal) controls maltese
fermentations Loe determines resistance to virulent Lambda
mutants, Both were known to be linked to § (streptomycin)
and usually hemizygous in otherwise heterozygous diploids,
Recent evidence suggests that both effects are apparently
pleiotropic manifestations of a single locis: 1) Existing
gtecks are either Mali“Lpo or Mal; *Lpe*. 2) When these
eultures were crossed, Mal*Lpo™ & p28 crossover re-
combinants were absent Géspite extensive tests. 3) On EMB
maitose agar MaltLoo™ colonies gave Mait reversions whish
proved to be Dpsts In turn, Mal~Lpo” reappeared among the
resiatant eueeieore after exposure the phage, lambda~2,
This mutation cycle was repeated several times in a mumber
ef stocks, Occasionally mutants resistant to lambda-2 ware
naltese~positive, These were tested by crosses with
Mal,“Lpe" and ascribed to mitation at any of several other
eet: Wenetically distinctive maltose-negative mutants
have been found with unaltered phage susceptibility. The
pleiotropy has elgo been noted in a gecom, probably non=
allelic mutant phenotypically identical with Malj“Lpo"
at 37° and Mal: bee at 30°, The dual effects aré there-
fore aesoc “at Gio loci, and soparated at others. All
the Male mutants ferment glucose, and are presumably
blectsd in tho cingle amylomaltese enzyme. Preliminary
attempts to uncever the possible physiological basis of
the correlation have been unsuccessful, The addition ef
either meltose or amylose to the medium had no influencs on
the phage reaction.

Reprinted fvom Genetics, 102580581, 1955.