Qi

FRIED, PHYLLIS J., and JOSHUA LEDERBERG, University of
Wisconsin, Madison, Wis.--Linkege in EB. coli K~12.--The
distribution of unselected markers among selected proto-
troph recombinants had implied that the known loci in £.

. Coli strain K-12 were located on one linkage group. In-
dependent verification of the linkage of Lag to M was
sought in crosses using other selected markers, so that
these were allowed to segregate. In MLact X-M’Lac™, both
M* and Lae” predominated. However, there was no inter-
action between these factors to verify their linkage to
each other, This was corroborated by the non-correlation
of the factors M, S, and Th, with P, Lac, and Vl, whereas
linkage correlations were found within each of the two
groups.--If both selected markers of a cross were confined
to one group, the segregation of the other nevertheless
deviated markedly from random. (The preferential appearance
in the segregants of the alleles contributed by one parent
has been asgociated with the polarity of a recentiy dis-
covered sex compatibility factor.)--The separation of M
and Lag into distinct linkage groups obviates the need
for postulating several mutually independent factors
linked to M (Lederberg et al. 1951, Cold. Spr. Harb.

Symp. XVI).

Reprinted from Genctics, 37:582, 1952.