December 24, 1961

New Horizons in Science

 

By Earl Ubell
Science Editor
Bruecke and I have sworn
to make the truth prevail: no
forces are effective in the
organism other than the purely
physical-chemical—-Emil Du
Bois-Reymond, 1847.
Eventually, physiology must
completely dissolve into or-
ganic physics and chemistry—
Emil Du Bois-Reymond, 1848.
* » *

When Du Bois-Reymond set
those brave words down as a
thirty-year-old biologist in
.|Berlin.more than a century ago,
they seemed as revolutionary as
the Communist Manifesto of
those same years. His call for
a physical-chemical basis for
life hammered at the prevailing
theory of vitalism:. the “old
men” believed an unseen, im-
measurable vital force gave the
spark to life.
In typical revolutionary
fashion and in keeping with the
times, the young men in science
rallied to the young Berliner’s
side. Bruecke was Ernst
Bruecke, who later became
Sigmund Freud’s physiology
teacher in Vienna. Hermann
von Helmholtz, then twenty-
seven and a founder of the
law of conservation of energy,
and Karl Ludwig, thirty-two, a
physiologist, joined the fight.
Of course, with their methods
they failed) to prove their
biological manifesto.
Last week another groyp of!
Predoninatitly” young ~ men}
announced they had come
closer than ever to prov-
ing the Germans right. They
had tapped one of the inner-
lmost. secrets of living things.
They had found the key to
the chemical code of life: they
had learned the basic ‘chemical
language of heredity and of the
living chemistry by which
protoplasm regenerates itself.
They had given more reason
than ever to believe that at
bottom the life force is chem-
istry and physics.
Credit for the fundamental
crack in the code goes to Dr.
Marshall W. Nirenberg, thirty-
two, of the National Institute
of Arthritis and Metabolic
Diseases, Bethesda, Md. Work-
ing with Dr. J. Heinrich
Matthaei, Dr. Nirenberg six
months ago deciphered the first
“word” of that code.

The News Leaks Out

When Dr. Nirenberg an-
nounced his achievement in
Moscow at the International
Biochemical Congress last
August, he set the world of
biochemistry abuzz. However,
the news did not leak into the
newspapers until last week. A
group of four researchers from
New York University announced
they had taken Dr. Nirenberg’s
code-breaking procedure several
steps further and deciphered
fourteen out of twenty words
of the code of life, and had thus
effectively broken it.

After this announcement by
the NYU group headed by
Nobel Prize winner Dr. Servo
Ochoa, Dr. Nirenberg’s insti-
tute announced that he and
Dr. Matthaei had also de-
ciphered as many words. At
week’s end, it seemed it would
be only a short time before the
full code was known, now that
its basic secret was revealed.

What is this code? What is
the “language” involved? What
are the “words?” These are
but metaphorical ways of ex-
pressing the great modern
question in biology: how does a
living thing transmit its char-

 

 

acteristic to its offspring?

The Code of Life
Finally Cracked

In the mood of 1848 trans-
ferred to today, biologists and
chemists know the transfer is
chemical. They know that
when sperm ‘unites with . egg,
chemicals are joined. When an
amoeba or a cell or a germ
splits in two, chemicals are
distributed.

It was only a few generations
ago that biologists traced the
site of those important chemi-
cals to the nucleus, the central
core of the cell; and in the
nucleus to the chromosomes,
microscopic rods.

Twenty years ago, they iden-
tified the chemical that carries
the hereditary. information—it
was called - deoxynucleic’ acid
(dee-OXY-NOO-KLEE-ik), and
known as DNA for short. The
past two decades have been
spent trying to understand its
chemistry. and its role in the
hereditary mechanism.

Composed of two long strings
of four basic molecules, per-
muted thousands of times, the
DNA holds the information for
the‘manufacture of proteins in
cells. The type and variety of
proteins make an animal the
size, shape and color if is. The
proteins, composed of twenty
different aminoacids, carry on
the basic life chemistry.’ |

Stull Unknown

But the biologists did not
know how the information from
the DNA moves from the
nucleus of the.cell. inte the pro-
tein manufacturing region, the |
cytoplasm, and into the ribo-
somes, the microscopic protein
factories. Recently they found
the role of the transfer agent
played, by. another chemical,
ribonucleic acid (RYE-bo-
NOO-KLEE-ik), a cousin to
DNA and known as RNA.

Unknown: What sequence of
submolecules in RNA (as trans-
ferred from the DNA) produced
the proper sequence of amino
acids in the proteins? The
whole sequence of RNA sub-
molecules—identified by letters
representing the 4 chemicals,
G, C, U, A—is the language of
life; eaeh three-letter combina-
tion is a “word.” Each word—
UUU, UAA, CUA, etc.—controls
the addition of a particular
amino acid to a particular pro-
tein.

Dr. Nirenberg fed artificial
RNA to the ribosomes. ‘This
artificial RNA had but one word
—UUU—UUU---UUU—repeated
over and over. The ribosomes
read the code and produced a
protein containing only one
amino acid, phenylalanine. This
was the news last August in —
Moscow.

The NYU group tried other
RNAs and worked out—with
some ambiguities still—the code
words for fourteen of the twen-
ty amino acids. Dr. Nirenberg
has also done so.

Future Uses.

This work has great practical
implications. If biologists know
the whole hereditary code and
learn how to change it at will,
they. may be able to. control.
heredity by chemical means.
They could raise plants and
animals of almost any desired
character, and do it in a hurry.

In human beings, it could
lead to control of hereditary
diseases like diabetes and gout,
to name but two. Some scien-
tists are even worried that it
could be applied to control the
intelligence of large human
populations wholesale; i. e.,
breed @ super-race. But all this
is in the distant future.

At the moment, the biological
manifesto of 1848 looks very
good indeed. ‘