October 29, 2017 Sunday
Bedtime Story
Mysterious Palindromic Interrupted Clustered Repeats
Yoshizumi Ishino at the Osaka University
was primarily interested in the cloning of gene iap of E. coli that coded for
the enzyme alkaline phosphatase.
This is an enzyme that removes the
phosphate group from organic compounds by hydrolysis and is widely found in the
cells of organisms, both eukaryotes and prokaryotes.
On cloning the iap gene, Ishino got the
expected iap product that contained 345 amino acids.
But along with that he also unexpectedly got
some mysterious short, palindromic repeat sequences of nucleotides.
(I must add that a genetic palindrome of
nucleotides is slightly different from that which is conventionally understood
in its English meaning and I shall not go further than that).
Ishino had no idea what these interrupted
clustered repeats were, so he simply stated that in his paper and moved on.
As a matter of fact he moved on to the
laboratory of Dieter Söll at Yale who had in his turn been tutored under the
great scientist Har Gobind Khorana at the University of Wisconsin-Madison.
Nothing much was reported on these
mysterious clustered repeats for the next six years.
Subsequent progress that happened in this
area came unexpectedly from two papers originating from Netherlands.
Both the papers were published in the year
1993, one in August and the other in September, the former in the Journal of
Clinical Microbiology and the later in Molecular Biology.
The first paper was titled “Comparison of
various repetitive DNA elements as genetic markers for strain differentiation
and epidemiology of Mycobacterium tuberculosis”.
The second paper was titled “Nature of DNA
polymorphism in the direct repeat cluster of Mycobacterium tuberculosis;
application for strain differentiation by a novel typing method.”
As you can see from the titles of both the
two papers, the Netherland team of molecular biologists never used the term
CRISPR but simply used the terms cluster and repeats.
Moreover, they seemed not to have given much
importance to the findings and all that they could think of was to exploit the
diversity of these cluster repeats of DNA in M. tuberculosis in classifying this
clinically important microbe into different strains.
So these cluster repeats of DNA was then primarily
being considered as a taxonomical tool for the various strains of M.
tuberculosis.
At about the same time in the early 1990s,
a microbiologist by the name of Francisco Mojica was investigating two
organisms from the kingdom Archaea at the University of Alicante in Spain.
As you will yourself agree, all the three
nouns of interest in the above sentence are totally nondescript; the
microbiologist, the university and the organisms.
Yet all will play a significant role in our
story that will continue to play out in the nights to come.
Stay tuned to the voice of an average story storytelling
chimpanzee or login at http://panarrans.blogspot.com
Good night mon ami and my fellow cousin ape.
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Another great educator and a teacher that I am aware of is
Professor Subhashish Chattopadhyay in Bangalore, India.
While I narrate stories, Professor Subhashish an electronic
engineer and a former professor at BARC, does and teaches real mathematics and
physics.
He started the participation of Indian students at the
International Physics Olympiad.
Do visit him here:
All his books can be downloaded for free through this link:
For edutainment and English education of your children, I
recommend this large collection of Halloween Songs for Kids:
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