New Technology
DETA coating for better DNA retention. Penn State
material scientists have developed a coating made of organic molecules
that tethers DNA to a glass surface, that may make DNA microarrays
denser and more affordable. The coating is licensed by Schott Glass
Technologies of Duryea, PA. Dr. Carlo G. Pantano, director of the
universitys Materials Research Institute, states, “The coating
is a single molecule thick, about one nanometer, in which the DNA that
attaches to this flexible leash is able to act as if it were free
floating.”
Tests show that the spin coating of liquid
3-trimethoxysilylpropyl diethylenetriamine, DETA, on the surface of the
glass deposited a uniform monomolecular layer coating that had a 50%
better DNA retention than aminopropyl triethoxysilane, the standard
coating. Silicon dioxide-based microarrays were found to have the best
retention of DNA, retaining 22.5%, which is as much as 17% higher than
other subtrates tested.
Pantano indicates that research on coatings for DNA microarrays is
driven by the need to put more spots on each slide so that more
potential drugs or genes can be tested at once. “With less
self-fluorescence, better adhesion of the DNA probes, and more
functionality of the tethered DNA,” he says, “we are moving in
the right direction. Perhaps we will find a way to produce re-usable
microarrays.”
Medical History
Century-old smallpox scabs discovered. Scabs from
19th-century smallpox vaccinations were found in a New Mexico university
library. Inger Damon, chief of the Centers for Disease Control and
Preventions (CDCs) pox virus group, thinks since the sample is so
old, it is “highly unlikely” that the scabs will yield live
smallpox, but believes the discovery could shed some light on the
development of American smallpox vaccines. Within days of the finding,
two FBI agents went to the library in Santa Fe to pick up the scabs.
Then on April 3 the same day the FBI received them the scabs
were forwarded on to the CDC in a triple-bagged, overnight mail package.
The sample now resides in a freezer at the CDC.
During the Civil War, many soldiers were treated for smallpox
at hospitals such as the the Minton House in Cape Girardeau, MO.
Susanne Caro, the librarian at the College of Santa
Fes Fogelson Library, found the scabs in an envelope inside an 1888
book on Civil War medicine written by Dr. W.D. Kelly who had done work
on childhood vaccinations in the late 1800s. The inscription on the
envelope read, “scabs from vaccination of W.B. Yarringtons
children,” and was signed by Kelly.
Caro contacted George Wunderlich, executive director
of the National Museum of Civil War Medicine in Frederick, MD, who notes
that during the late 1800s, pus or bits of scabs from smallpox patients
with mild cases were implanted in the skins of healthy people to
generate a mild illness that bestowed lifetime immunity. The practice,
used in the early 18th century, predated the cowpox-based vaccine that
later became standard. Cowpox virus was used in inoculations in 1796 by
Edward Jenner.
Paul Sledzik, a forensic anthropologist at the Armed
Forces Institute of Pathology at Walter Reed, after speaking with
Wunderlich, stated, “To be able to look at an untreated specimen
from the 19th century using the tools of today is incredible. If you
want to look at disease evolution, this would be the perfect opportunity
to do that.”
According to Damon, “This could lead to a
greater evolutionary understanding of the smallpox vaccine were using
in the United States. It all depends on whats in there.” Through
a series of tests slated for next year, the CDC hopes to develop a
genetic portrait of the virus used in the vaccine likely cowpox.
“These scabs will potentially be the oldest material well
have looked at in terms of being able to determine any kind of genomic
characterization,” says Damon.
News
Unique laboratorians. In an unusual report from Dar Es Salaam, Tanzania, the Associated Press reported on Dec. 15 that giant pouched rats (Cricetomys gambianus) trained to sniff out land mines in Africa are now learning with the help of a $163,780 grant from the World Bank to detect tuberculosis (TB) bacteria in human saliva. The rat can sniff 120 to 150 human saliva samples in lab dishes in 30 minutes compared to the days work it takes for a human technician to analyze 20 samples. The rat stops in front of samples that smell like TB and waits to be rewarded, but walks past samples where TB is not present. Some of the grant funds will be used to build a new lab to test for TB at the research station at Sokoine University of Agriculture in Morogoro, 100 miles west of Dar Es Salaam. February 2004: Vol. 36, No. 2
