Artist's representation of the CRISPR-Cas9 system (Image source: phys.org) |
By: Renald James Legaspi (Polinton)
Changes in the
genetic material brought about by infections and environmental stresses, in
most cases, leave molecular traces in the cell. By practice, researchers could
accurately trace these changes by measuring the gene activity through the
transcript or mRNA equipped with the molecular traces. However, due to the high
instability of mRNA, it tremendously decreases the efficacy for tracing cell
history. Thus, a novel method using CRISPR-Cas System provides a more promising
approach for this cause.
Randell Platt, a
researcher from the Department of Biosystems Science and Engineering, and his
colleagues developed a permanent molecular recording method by writing
transcriptional events into DNA that is re-accessed through sequencing.
The group
employed the use of CRISPR-Cas System known to offer prokaryotic adaptive
immunity. Naturally, this system records the genetic information of mobile
genetic elements infecting a certain organism through the process known as
CRISPR spacer integration.
Spacers or the
pathogen-acquired sequences are separated by direct repeats and are closely
associated with the genes required in the mechanism of the CRISPR System. These
associate genes are generally called cas genes.
Platt's method
made use of E.coli wherein the group infused one of the cas genes
with a reverse transcription allowing DNA synthesis from an RNA transcript.
These acquired DNA are stored in the CRISPR array, which is a process similar
to a recording device or a computer memory storage.
More
importantly, according to the group, this process could be repeated multiple
times using a single CRISPR System allowing the possibility of several spacers
in an array.
Using the
order-logic, a certain DNA sequence could be traced upon and its order of entry
compared to other sequences by counting the direct repeats naturally flanking
between spacers.
"Researchers
have been working on creating forms of synthetic cellular memory for a long
time, but we are the first to develop one that can record information about the
expression of each gene in a cell over time."
As said by
Randall, this technique not only provides with a recording device of a cell's
history but allows the creation of ordered and logical inferences, for it uses
a system that is naturally efficient and stable in nature.
For these, the
team spent two years of labor but is dedicated to spend more years for the
endeavor of this revolutionary method.
Reference:
ETH Zurich. "Recording device for cell history."
ScienceDaily. ScienceDaily, 3 October 2018.
<www.sciencedaily.com/releases/2018/10/181003134441.htm>.
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