TLlIEe THE CLuL

Vhat is different about self=-reproducing matter? Jlow does a s.eak
you eat turn into you and a steak I eat turn into me? Biologists have
@ new cluee In the last few years they have isolated the tanplates inside
every cell] which keeps living material organised in its ovm pattcrn,
These templates are the nucleic acids CNA, short for desoxyribormmeleic
acid and ite gmk similar colleague, RNA, short for ribommcleic acide
Both molecules are long strings of thousands of familiar groups of atoms
whose indivicual patterns of recurrence make the difference between a cell
of you and a cell of mae

Five years ago, when he was only 25, Chicago-born James Tf. “atson
and the English physicist F.H.C. Crick worked out a model of the TNA
molecule in the Cavendish Laboratory at Cambridgse They surcested that
it acted as if it were two commlementary strings wound arou@h each other
and held together by crocs brace groups. Urarind the strings and you
have two identical chaing of molecules run:ing in opposite dircetions .
The stumps of the broken cross braces could then attract, assemble, or
"grow" just the groups of atoms needed to make a new partners

Proof of this model is enrvaring biochemists and biolorists all

over the world,

 

a Now Assistant Professor

of Biology at tiarvard, tr. “atson is trying to correlzte the structure

of the DNA molecule with its biological role as the key ,enetic matcrial,
Thirty~three~year-old Joshua Lederberg, newly aspoi tec chairnan

of the newly ereuted d partment of nedical scnetics at the Univercity af

Wisconsin is a young biologist who has helped suscest a new answer to

an old question, low did sex begin? ‘Sexual recrocuction is the key to

evolution because 14 cluffles genes fran two parents to procuce inivicuals
who vary just enough for natural selection, but how did nature hit

on this marvellous device? ta The single-celled bacteria which reprocuce

by the siaele srocess of slitting co not sound like a promising approach

but that's just where Josh Lederberg and Edward Le “tum found the cluee
Lederberg wus a 2l-ysar<-old gracuate schoo] at Yale when he

started working on Tir rw
bacteria,

         

      

met iad

at the

Li

 

Rockefeller Inctitute for Medical Research had changed one pneumonia
bactcria into another form by artificially injecting its TNA into the
alien cell, #€ Could bacteria transfer [NA to cach other naturally?
Lederberg and Tatum
xed different strains of bacteria torether on the same plate
they got one in a million offspring with characteristics of both, like
Mendel's crossed pease ‘Further studies of bacteria at the University
L Lederberg

of Wisconsin convinced immfthat bacteria have genes strung along chromosomes
just like higher forms of life and that some bacteria are "males" am
who can give characteristics to "females" even though they don't need
sex to reproduce, The males smigzle up to the f-males and slide part
of the long DNA molecule into them, It takes a half hour. When the
female splits, wah offspring just divide the rconetic material,

Lederberg's work has won him many awards, including the £1i
lilly citation for 1953 as the oustanding young bacteriologist. llis
work on the sex life of bacteria equips biolorists with a perfect lab=
oratory animl for the study of reneticse Bacterias are simple,
compact, mmmubigeiien cheap to keep, prolific, and a new generation

is born every tverty mimtese