Inside Salk 12 | 15www.salk.edu
DECODING THE BOOK OF LIFE
holds out what looks like a glass
business card with four pencil-thin lines run-
ning across it. Each line is a channel that can
hold up to about 150 million fragments of DNA
from samples such as, for example, a diseased
brain and a healthy brain.
After one side of the double-stranded DNA is
stripped off, the sample-laden card—known as
a flow cell—is fed into a box-shaped machine
called a sequencer. The sequencer reloads
matching molecules, sequences of four nucleo-
tides (adenine, thymine, cytosine and guanine)
onto the DNA. But these replacement A, T, C
and G nucleotides are tagged with colors,
allowing a camera inside the machine to cap-
ture a snapshot of the newly colorized DNA and
decode what exactly those sequences are.
Despite only being made up of four letters, so
to speak, our DNA—and all the accompanying
bits that hang onto it—is still a puzzle to read.
It has been described as a book in which there
are no spaces or punctuation marks and with
letters thrown in at random. But decoding this
book is the key to understanding disease and
health, development and aging.
Manching Ku, director of Salk’s Next Generation Sequencing Core, holds a flow cell containing samples of DNA, which will be entered into a sequencer for decoding.
A flow cell can hold several million
fragments of DNA samples.
for integrating human stem cells into nonviable
mouse embryos in a dish. The work, published
in the journal
in May 2015, garnered
international attention for being a critical pre-
cursor to regenerative therapies.
“The core’s state-of-the-art technical support
for projects involved with the routine mainte-
nance, characterization and differentiation of
human pluripotent stem cells was critical to
this work,” says
, first author of the
paper and postdoctoral researcher in
the Izpisua Belmonte lab. “The customized
basal media provided by the Stem Cell Core
was one of the key components for generating
these human region-selective pluripotent
The discovery prompted much interest from
other labs at Salk, to the point where Boyer
acquired the chemicals and protocol for the
technique so that everyone could use it. She
is currently working with Wu to optimize and
outline an easy-to-use protocol.
“The cores are facilitators of research and
the hubs of collaboration—we make science
more cost-effective, time-efficient and robust,”