November 14, 2017 Tuesday
Bedtime Story
Encoding the Genetic Code of Bacteriophages
Last night I had left you with few lines of
Hankin’s 1896 paper wherein he was describing bactericidal action of the waters
of Ganges and Yamuna.
Like a true scientist he simply mentioned
his observations but did not venture to make any conjectures.
Hankin very unknowingly was describing the
presence of bacteriophage in the rivers of Yamuna and Ganges that had
bactericidal actions against the Vibrio cholera.
It would be 20 years later that the French
microbiologist Felix d’Herelle and the English bacteriologist Frederick Twort
would go on to discover and isolate the phages.
As always, the English will go on to claim
that they made the discovery first before the Frenchman.
Thus the claim that our boatman was making
about the river of Ganges was true to some extent though he was clearly wrong
in giving it a divine or supernatural twist.
Now in 2005 claim was being made that these
same bacteriophages or rather their genes formed the spacers in the
repeat-spacer array of CRISPR genes.
Here for the first time theory was proposed
that the spacers are fragments of DNA viruses gathered from viruses that had
previously attacked the bacteria.
Now the question arises that why would bacteria
or species of Archaea store genes of their enemies within their own coding?
Knowing how immune system works, the
natural question that arose was that could the CRISPR-Cas system could be
playing the role of microbial immunity for the bacteria?
This idea tentatively put forth by the
three groups was out rightly and flatly dismissed by the established doyens of
that time.
Now see once again how closely related biological
genetics is related to digital technology and how intimately they go together.
Mojica was now targeting the sequence in
the spacer parts of the repeat-spacer array of CRISPR genes.
Mojica had the sequence of the spacers.
He fed them into a program or an algorithm
that is known as BLAST.
BLAST stands for Basic Local Alignment
Search Tool that compares any primary biological sequence information, may they
be amino acid sequences of proteins or nucleotides of DNA or RNA sequence with
known sequences in its data base.
With this program one can compare any
particular query sequence with database of sequences so that one is able to
identify the query sequence.
BLAST is the perfect merger of human
digital technology and the biological digital technology and no wonder it is
the most widely used bioinformatics program used for sequence searching.
It was first published in 1990 in the
Journal of Molecular Biology in 1990 and it has an astonishing more than 50,000
citations.
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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