20
THIN;; YOU DIDN’T KNOW
ABOUT DNA
BY KIRSTEN WEIR
ILLUSTRATION BY
JONATHON ROSEN
1. Sorry, Jimmy: James Watson and Francis Crick did
not discover ;;;. ;at honor goes to Swiss biochemist
Friedrich Miescher, who in ;;;; found the molecule in
the nuclei of white blood cells and called it nuclein.
2. Nor did they ;gure out that ;;; is our genetic blueprint; bacteriologist Oswald Avery and his colleagues
did that in the early ;;;;s. 3. What Watson and Crick
did do, in ;;;;, was decipher the double-helix structure
of ;;;. ;eir discovery ran as a single-page paper in
Nature. 4. Phosphorus is a key component of ;;;, but
late last year a team of ;;;; scientists announced
they had found a bacterium that could use arsenic
instead. “What else can life do that we haven’t seen
yet?” wondered lead researcher Felisa Wolfe-Simon.
5. Don’t try this at home: If uncoiled, the ;;; in all the
cells in your body would stretch ;; billion miles—from
here to Pluto and back. 6. Most of that ;;; resides not
in the cell nuclei, which control heredity, but in our
mitochondria, the organelles (units within cells) that
generate metabolic energy. 7. Puny humans: Paris
japonica, a ;owering plant native to Japan, has the long-est known genome, nearly ;;; billion base pairs. ;at’s
;; times as long as the human genome. 8. Aside from
bacteria, the smallest genome belongs to the intestinal parasite Encephalitozoon intestinalis, with a tri;ing
;.; billion base pairs. 9. Scientists are working to
create vaccines against ;;;, ;u, and hepatitis C from
snippets of synthetic ;;;; the ;;; tricks the body
into producing harmless viral proteins that train the
immune system to attack real viruses. 10. ;;; vaccines for West Nile virus, melanoma, and hemorrhagic
disease are already available for horses, dogs, and
salmon, respectively. 11. At the Chinese University of
Hong Kong, fetal ;;; was extracted from a pregnant
woman’s blood plasma and tested for Down syndrome.
Prenatal ;;; screening could someday replace amniocentesis. 12. Telomeres, sequences of ;;; at the tips
of chromosomes, get shorter every time a cell divides;
when they get too short, the cell dies. Some scientists
are trying to extend life by extending the telomere.
13. Good news if you’re a mouse: Researchers at
Dana Farber Cancer Institute in Boston engineered
mice with telomerase (an enzyme that adds ;;; to
telomeres) that could be switched on and o;. With
the enzyme activated, the mice grew new brain cells
and lived longer. 14. Bad news if you’re a mouse:
Scientists at Osaka University recently developed
mice that are especially susceptible to ;;; copying errors, seeking to increase the rate of mutations
and see what new traits appear. 15. ;e results so
far include short-legged mice, mice with fewer toes
than normal, and mice that chirp like songbirds.
16. Guess who’s in your ;;;? At least ; percent of the
human genome originated in viruses, whose genetic
code was integrated with ours over roughly ;; million
years of primate evolution. 17. Over the next ;ve
years, the International Barcode of Life Project aims
to establish genetic identi;ers for ;;;,;;; species—
short sections of unique ;;; in the same location on
the genome, a bit like the ;;; on your box of Froot
Loops. 18. Already, forensic specialists can identify
criminals from traces of “touch ;;;” left in ;nger-prints at a crime scene. 19. Next up: food forensics.
British microbiologists sequenced ;;; to identify
the bacteria in a round of Stilton blue. ;ey found
that at least six microbial groups in;uence the ;avor
of the cheese’s “dairy matrix.” 20. And scientists at
the University of Guelph in Ontario showed that ;;;
from the worm (actually an agave butter;y caterpillar)
traditionally placed in bottles of mescal leaches into
the liquor. So now we know: You don’t actually have
to “swallow the worm” to swallow the worm.
DISCOVER (ISSN 0274-7529, USPS# 555-190) is published monthly, except for combined issues in January/February and July/August. Vol. 32, no. 3. Published by Kalmbach Publishing Co., 21027 Crossroads Circle, P.O.
Box 1612, Waukesha, WI 53187-1612. Periodical postage paid at Waukesha, WI, and at additional mailing offices. POSTMASTER: Send address changes to DISCOVER, P. O. Box 37808, Boone, IA 50037. Canada Publication
Agreement 40010760, return all undeliverable Canadian addresses to P.O. Box 875, STN A Windsor, ON, N9A 6P2.
Back issues available. All rights reserved. Nothing herein contained may be reproduced without written permission of Kalmbach Publishing Co., 90 Fifth Avenue, New York, NY 10011. Printed in the U. S. A.
