D. Genetic functions of bacterial viruses (Br. EB. M. Lederberg and Mr. M. L. Norse)
A study ef the genetic preperties of a symbiotic bacteriophage, lanbda,

was initially undertaken in this laboratory in the expectation that it would

behave as a cytoplasmic facter or plasmagene. Instead there has accumlated

| very substantial evidence that in its stable synbiotic condition, the lambdg

functions as a part of the chromesomal make-up ofine bacterium. In crosses of .

lysogenic (that is, lanbda-carrying) bacteria vith nen-lysogenie strains the

property of lysogenicity is found te segregate just like any other genetic

trait and is in fact closely linked to genetic factors fer galactose fornenta-

tien. This finding has been greatly strengthened by the isolation of diploids |

heterozygous beth for lysogenicity and for galactose fermentation. These dipleids

segregate primarily the two parental comusnasions of onese traits toget
ote Ha Bolan _trpits tosetper ae
eccasional crossevers. Other students <stpeoreumaney have subsequently adduced
confirmatory
- gonsiderable/zax evidence of other kinds in suppers of the chromesomal
fLization of the bacteriophage in lysogenic syst to a rural slisre. foi
stm bes

The genetic functions of 1 rdaqdbireeore-ing OS CEI GE ue Sie |
etic Tunctiens o an actose f r e °

played in a converse way in a transduction phenome, that is, particles of

  

lambda are capable of transducing the genetic quality ef the bacteria en which
they have grown, with respect to galactose fermentation, to their new bacterial
hosts. This transduction is set off from the Salmonella transduction in at
least two ways: (1) Whereas in Salmonella every genetic trait of the bacterium :
is equally liable to transduction by phage, in E.’coli only the factors con-
trolling galactose fermentation, which are clesely linked te the site of fixza-
tien of the Lanbaa, are capable of transdustion; (2) In Salmonelia the immediate
produsteof transduction, se far as can be ascertained, already wee the perma-
nent displacement of the previous genetic material by the newly transduced home-
logues. In 3, coli there is a long-lasting intermediate stage in which beth the
xen original and the newly transduced genetic material aanfrexiss, This on
~ 2a

however be followed by a crossingover and permanent unique implantation ef the
. transduced material. From many points of view the B, coli aysten goons to be
more favorable for a study of the fundamental processes of ‘sranstuo tion, ant-te

 

The bearing of thes /tindings
on the general probleas of virus biology does not need to be exp Keay ever-
emphasised. |