RESEARCH
Another Piece in the RNA Puzzle S e q u e n c e s of building blocks d e t e r m i n e d p r o a c h using highly specific e n z y m e s ONE
MORE
step
in unravelinu
the
complex structure of nucleic acids has been taken by K. K. Reddi at the I'niversit\ of California's virus laboratory. By digesting nucleic acids with an enzyme which attacks only a specific linkage. Reddi has established the ar rangement of the nucleotides in por tions of the nucleic acid chain. Nucleic acids have chains of mono nucleotides which differ from one an other only in the nature of the purine or pyrimidine radical attached to the ribose ring. Nucleic acids from diflrrent sources differ in type and in propor tion of their component nucleotides. However, three strains of tobacco mosaic virus which exhibit definite hiological differences all have the same purine and pyrimidine composition. It is a reasonable assumption that the differences in biological activities are connected with differences in the arrangement of the pyrimidine and purine nucleotides along the chain. But Reddi's work offers the first proof of this assumption. Reddi digests nucleic· acid from to bacco mosaic virus with pancreatic ribonuclease—a highly specific enzyme. Examination of the digestion products then gives evidence for the arrange ment of the purine a n d pyrimidine nucleotides. Results obtained so far show that these nucleotides occur in clusters of two or-more as well as alter nating with each other. There is a certain regulariU in the mode of ar rangement of both the purine and the pyrimidine nucleotides which suggests that the distribution is not random. • Results. So far, Reddi has identi fied three dinucleotides and one tri nucleotide in the ribonuclease digest. Since each of these must be preceded in the chain by a monopyriinidine nucleotide, he establishes the existence of specific (or almost specific) threeand four-unit sequences. These se quences account for more than 70' Ί of the known content of pyrimidine nucleotides and about half of the con tent of purine nucleotides. Moreover, he has used a similar technique to demonstrate the presence of" seven different dinucleotide se-
by ap
c• |iinic*c*s. Here he employs an en/y me ( ohlained from bacterial sources) •v* liieli is more exhaustive in degrading UNA than is pancreatic libonuclease. "The exact type of bond is not yet IN nown. Redcli finds that the three -strains of tobacco mosaic virus have .'
SCIENTIFIC GLASS APPARATUS C O . , I N C . BLOOMFIELD, N E W JERSEY
estinghouse FIRST IN A TOMIC PO WER Offers Challenging Opportunités at the
NAVAL
National Aeademv of Sciences meeting in Berkeley. Calif., shows that nuik* mice kept on 30' * deutei nun oxide iτ ι their drinking water lor eight weeks become compîeteîv sterile. Fertilitv returns 3 0 to SO dav s after hea\ ν water is removed from t h e diet. The precise cause of this sterilit\ is still unknown, h u t A. M . Hughes of _.() admin istration, and this can h e compared with t h e known spermatogenic cycle of the mouse. From this comparison, ( "alvin's group deduces that sterility r e sults from interference with the very t arly stages of sperm formation —before the first maturation division, in fact. It is at this stage that t h e rearrange ment of the chromosomes occurs. Pos sibly this interference with the sperm production process is d u e t o a lethal mutation caused by changes in t h e hydrogen hooding of t h e chromosomal nucleoproteins. Hydrogen bonding is known t o he important in determining the s h a p e of t h e nucleoproteins a n d hence controls cell development t o some degree. If these bonds a r e weakened by substituting a few deuterium atoms for hydrogen atoms, mutations could well result. This technique (feeding D..O to ex perimental animals) a d d s another tool to those already being used to unravel the structure and mode of action of t h e nucleoproteins.
REACTORS FACILITY Idaho Falls, Idaho uss NAUTILUS WORLD'S riRST F«ACTICAL APPLICATION Of NUCLEAR POWER ATOMIC POWtR BY WCST1NGMOUSE
W E S T I N G H O U S E e m n l oyes w o r k i n g a t the N a v a l Reactors F a c i l i t y live i n t h e center of the n a t i o n ' s most versatile r e creational area . . . fishing, hunting, boating, c a m p i n g , skiing. PHYSICAL O R I N O R G A N I C CHEMIST OR C H E M I C A L ENGINEER, advanced degree or equivalent experience. Will perform solid-liquid separations, corrosion tests, gamma rây spectrometry, colloid chemistry, analytical and radiochemistry procedures. SENIOR M A S S SPECTROSCOPIST to direct developmental work m fully equipped mass spectrometer laboratory, Phd or MS «n Physical Chemistry/ experienced in electricity and analytical instrumentation. Additional openings for Electrical or Mechanical Engineers with steam plant operating experience.
Send resume to:
Westinghouse Electric Corporation Personnel Services, P. O . Box 376, Idaho Falls, Idaho 42
C.&EN
N O V . 24, 1958
• A n e w , germ-free
l a b o r a t o r y has
been built at the University of Michi gan medical center. It will be used to study t h e role of organisms in the life of humans and animals. • The bulk of naturally occurring radioactivity in t h e air is d u e to radon -and its decay products (Science, Nov. 7, p a g e 1139). This radioactivity conies from radioactive decay of radium in t h e soil a n d t h e consequent diffusion of radon gas into the air. fc The
Institute
of Paper
Chemistry
gets a grant of $50,000 from Louis C'alder Foundation to establish a n e w lab, t h e Lou Calder Plant Biochemistry Laboratory. T h e n e w l a b will study the mechanisms of wood development, is expected to b e complete by March 1, 1959.
