November 04, 2017 Saturday
Bedtime Story
Ruud Jansen in his 2002 Paper Names the Repeats as CRISPR
It was thanks to Ruud Jansen that these
mysterious short tandem palindromic repeats finally had a name (in the print
for the first time in 2002 and whose abstract I shall be quoting below).
It has to be borne in mind that even if now
named and confirmed, the function of this CRISPR still remained unknown.
Various functions were attributed to CRISPR
that ranged from playing a role in gene regulation to replicon partitioning, from
DNA repair to sundry other possible functions that a gene can encode for.
All of the conjectures turned out to be
wrong.
The next breakthrough came in the form of March
2002 paper by Ruud Jansen of Utrecht University, Netherlands in Molecular
Biology.
The paper was titled “Identification of
genes that are associated with DNA repeats in prokaryotes.”
This data threw some light to the mystery
behind these repeats but not adequate enough to draw any meaningful conclusion.
In this paper Ruud Jansen and his team from
Utrecht showed that the prokaryote repeat cluster came along with a set of
homologous genes.
Let me directly quote the abstract of this
verbatim:
“Using in silico analysis we studied a
novel family of repetitive DNA sequences that is present among both domains of
the prokaryotes (Archaea and Bacteria), but absent from eukaryotes and viruses.
This family is characterized by direct
repeats, varying in size from 21 to 37 bp, interspaced by similarly sized
non-repetitive sequences.
To appreciate their characteristic
structure, we will refer to this family as the clustered regularly interspaced
short palindromic repeats (CRISPR).
In most species with two or more CRISPR
loci, these loci are flanked on one side by a common leader sequence of 300 –
500 bases.
The direct repeats and the leader sequences
were conserved within a species, but dissimilar between species.
The presence of multiple chromosomal CRISPR
loci suggests that CRISPRs are mobile elements.
Four CRISPR-associated (cas) genes were
identified in CRISPR-containing prokaryotes that were absent from
CRISPR-negative prokaryotes.
The cas genes were invariably located adjacent
to a CRISPR locus, indicating that the cas genes and CRISPR loci have a
functional relationship.
The cas3 gene showed motifs characteristic
for helicases of the superfamily 2, and the cas4 gene showed motifs of the RecB
family of exonucleases, suggesting that these genes are involved in DNA
metabolism or gene expression.
The spatial coherence of CRISPR and cas
genes may stimulate new research on the genesis and biological role of these
repeats and genes.”
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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