Page 2
WEALTH & SCIENCE
Tuesday • July 12,199^
DNA identification
Procedures can put investigators 'at the scene'
in murder cases, says Texas A&M geneticist
By Ellie Hudson
The Battalion
DNA testing allows prosecutors to positive
ly identify or exclude murder suspects, says
Dr. Jim Womack, a mammalian geneticist
with the Texas A&M Veterinary School.
“The technique is powerful enough to put
them (suspects) at the scene,” he said. “I
firmly believe that.”
Womack is currently working on a project
to map the genome, or set of chromosomes,
of domestic cattle and has served as an ex
pert witness in court to the validity of DNA
testing.
“The test relies on not any of us having the
same DNA makeup, except for identical
twins,” he said.
There are two types of DNA testing, called
Restriction Fragment Length Polymorphism
(RFLP) and Polymerase Chain Reaction
(PCR).
A lab technician for the Travis County
Medical Examiner’s office said RFLP is used
for large quantity samples and gives the best
statistics for determining the frequency of al
leles (the units that carry a gene’s traits) in a
population. Once it is known how frequently
a certain trait occurs in a given population,
the likelihood of that trait appearing in both
samples can be calculated.
She said PCR is used for smaller samples.
This process works like a photocopier, making
multiple gene copies from the given sample.
However, if the sample has any contami
nants, these get amplified as well, which can
skew the results.
“The best results occur when several sys
tems are used together,” the technician said.
“The easiest (sample) to get DNA from is
straight liquid blood.”
Womack said, “Its (DNA’s) value as evi
dence depends on the quality of the sample.”
Norm Carmack, administrative assistant
to the Travis County chief medical examiner,
said DNA samples can be obtained from
blood, semen, hair, skin or saliva. The struc
ture of the DNA is obtained from these sam
ples and then compared to the DNA structure
of a known suspect.
Barry Wilkerson, crime scene technician
for the College Station Police Department,
said the chances of someone’s DNA match-
Genetic “fingerprinting” is possible because there are
short sections within each person’s DNA which are unique
to that individual (except in the case of identical twins).
Samples of hair or blood from a crime
scene can be processed to extract
the DNA (deoxyribonucleic
acid). Each human cell contains
about five feet of coiled DNA strands.
Simpson defense
faces DNA testing
LOS ANGELES (AP) - A fierce
battle to block DNA evidence, ef
forts to explain away a trail of
blood and a search for new alibi
witnesses face O.J. Simpson’s de
fense team as it plots strategy for
his murder trial.
With a preliminary hearing of
fering a hint of the evidence, it’s
clear that the murder case against
the famous defendant is far from
open and shut.
In the end, Simpson’s guilt or in
nocence may be decided by scien
tists who analyze the murder
scene’s gore - blood, hair, fingernail
scrapings and wound patterns.
“There’s a lot of hard work
ahead for the defense,” said crimi
nal defense attorney Barry Tarlow.
Tuesday *
DNA matching
takes 10 to 12 weeks
to complete and is
said by forensic ex
perts to be 99.99 per
cent accurate.
ing another person’s is one in five billion,
which provides better results than blood-
type testing.
However, Wilkerson said finger printing is
still the most accurate form of identification,
as it is almost 10 times more accurate.
Wilkerson said samples are best when
fresh at collection or if they are frozen imme
diately. Once the DNA starts to break down,
however, the data is not as reliable.
Texas law in 1988 made DNA testing ad
missible evidence in court.
DNAfrom blood or hair found at
crime‘scene and DNAfrom
suspect are cut into short
fragments by an enzyme.
Ttaqin nxoTt abisA j
The DNA-fragments are a
processed. Patterns derived
from both DNA samples can
be compared like fingerprints.
Sample from crime scene
Sample from suspect
“They’re dealing with the awesome
resources of the district attorney’s
office.”
Boston attorney J. Albert John
son, who practices with a member
of Simpson’s legal team, F. Lee Bai
ley, said Simpson’s lead attorney,
Robert Shapiro, must become an
expert in DNA fingerprinting and
prepare to fight the admission of
such genetic evidence at the trial.
Based on an individual’s unique
genetic makeup, DNA matching
takes 10 to 12 weeks to complete
and is said by forensic experts to be
99.99 percent accurate.
Nonetheless, Johnson said, DNA
evidence is inadmissible in some
states, atlti Pgteb'Arenella, S. law
professor at the University of Cali 1
fornia, Lbs Ahge'les, said a recent
appellate decision in California ex
cluded the most sophisticated form
of DNA testing from a criminal
case because the statistical sample
was inadequate to make it trust
worthy.
“There is going to be a major
fight about DNA testing,” Arenella
said.
But University of Southern Cali
fornia law professor Erwin
Chemirinsky said defense lawyers
should not underestimate the pow
er of simple blood tests.
“People have gotten the impres
sion that without DNA testing,
blood evidence is untrustworthy,
but that’s not true,” he said.
“Countless defendants have been
convicted on serological evidence.”
MARK
SMITH
Sports E
A
bri
doA
stii
park in .
thousan
their firsi
ture into
Tom I
with the
White S(
Thomas i
lead 12-9
Henk«
wipes the
He winds
launches
right fieh
to the ws
but in ke
set by Jc
Pele-style
ball into i
run. Thi
Rangers
under .50
playoffs.
Meanwh
A few
Arlingtoi
team ph
lights i
domed st
the mou
Fred Me
taking a
The Astr
Hudek
his risin]
Center f:
through i
ly would
McGriff.
do the di
Reds wh
game. .
above .5
another ;
tnhf>r ”
Doesn
Realignn
AP graphics by Karl Tate. Sources: Cellmark Diagnostics; The Almanac
of Science and Technology; Scientific American
With th
League Be
gional ri\>
the divis
sense. Bi
teams int
other tean
a sh
first
The:
mg
hav<
in tl
,50(
thr
Small college makes super-sized discovery
This star died when the dinosaurs died/ says professor
BOSTON (AP) — Less than
two months after tiny Wheaton
College began its supernova pro
gram, a professor and students
made an exciting discovery — a
brightly burning star that col
lapsed on itself about 65 million
years ago.
The rare supernova was the
first discovered by a small col
lege program. Wheaton has
1,300 undergraduates at its
campus in Norton.
Professor Timothy Barker,
who founded the fledgling pro
gram, pinpointed the star.
“This star died when the di
nosaurs died,” Barker said.
With the help of students,
Barker spent 10 years preparing
for the search project, creating a
computer program that would
instruct a 14-inch telescope to
focus on 1,200 galaxies in se
quence, one every 30 seconds.
“The significance is the heroic
effort and the great job these
guys did,” said Carl Pennypack-
er, co-director of a more sophisti
cated supernova search at the
University of California, Berke
ley. “I think it’s a triumph of will
and dedication.”
In late May, Barker and his
students began spending their
nights on the roof of the school’s
science center, looking for dying
stars on a TV monitor linked to
a light-sensitive camera that
looks through the telescope.
If the monitor shows a bright
star that’s not on the map, they
have their first clue to what
might be a supernova.
Barker spotted such a star
just before midnight on June 26,
smack in the middle of galaxy
NGC 4948.
He said he wasn’t sure how
far the star is from earth.
wmmmm
Is there really such a thing as ‘safe sex’?
By Trey Dublin
A. P. Beutel Health Center
Is there really a means to having safe
sex? The phrase “safe sex” is under fire be
cause of the true meaning of the phrase.
The phrase “safer sex” has replaced “safe
sex” when referring to reducing the risks of
acquiring sexually transmitted diseases
(STDs) through sexual contact.
In examining the change from the stan
dard belief of safe sex to one of safer sex,
people should keep the following circum
stances in mind:
The reasons for the change from safe sex
to safer sex lie primarily in the definition of
the term “safe.” “Safe,” when used in con
junction with sex, has a strict meaning.
Webster’s dictionary defines the term “safe”
as being: freed from harm or risk; secure
from threat of danger; affording safety or se
curity from danger, risk or difficulty; not li
able to take risk. This definition of the term
allows for no mistakes or margin of error.
There is not a means of sexual contact
that would eliminate all risks of sexually
transmitted diseases. The only way that
this can be reached is through abstinence.
To use the phrase “safe sex” would lead to
the conclusion that there is no chance that
an STD can be transmitted from an infected
individual.
Another reason for using the phrase
“safer sex” is that there are individuals who
practice methods of safe sex incorrectly.
There are various ways to reduce the risk
of transmission of STDs, but when they are
used ineffectively, the chance of infection in
creases.
Some ways to reduce the risk of infection
include: wearing a condom and using a
birth control foam, jelly or lubricant contain
ing nonoxynol-9.
Improper use of the condom is a common
error. Some mistakes that are made con
cerning condom use include putting the con
dom on wrong, not using a water-base lubri
cant and improper storage.
All of these mistakes can lead to an in
creased infection risk. When used properly,
the methods of having “safer sex” are effec
tive in decreasing the risk of contracting
STDs.
The next time one uses the term “safe
sex,” he or she should think carefully and
question the validity of the phrase. Is there
really such a thing as safe sex?
The Battalion (U
spring semesters
holidays and ex;
Station, TX 7784
POSTMASTER:
A&M University
Measuring up
Stew Milne/ The Battalion
News: The Bait;
Division of Studi
013 Reed McDo
Edsel Sledge of Mesas surveys the grassy area between the
O&M building and the Langford complex so he can map out
the site. Sledge was participating in Camp Planet Earth, tak
ing place this week at Texas A&M.
Advertising: Pul
Battalion. Fora
advertising, call
a.m. to 5 p.m. fv
Subscriptions: f
year. To charge