Interestingly, I am writing about
an organism which always amazed me and I took so long to write some words about
it. I studied it in detail, during my graduation. Introduction to these
creatures during my curriculum made me more curious about them. It also imbibed
another fact on to my brain, that biology is fascinating.
Recently I had a fever for a week
or so, not something usual (since generally common cold and fever is seen for
2-3 days). It was a viral infection, as I was told. I was actually spending a
lot of time with somebody of other species (unwanted although). It was a wait
and watch. I could only wait for him to leave my body, as he was using my own
cells to replicate his genetic material. There was nothing anybody could do,
except for suppressing the symptoms he creates (fever). This is the smallest
demonstration of power by these creatures. Pandemic Flu of 1918 (~ 50 million
people died) and many such attacks show the real power (potential) of the one
of the tiniest species on earth.
The theory put by Urey-Miller
explaining chemical origin of life and generation of organic molecules
including all 20 amino acids by a simple chemical reaction under reducing
environment and available high electrical energy seems to be an explanation for
what was the starting point from where life originated on earth. Lets believe
for a moment that it was an accident (really hard to believe, but I will put my
vote onto it), but since then life has never given up. Since its formation, it
has been struggling to survive and has adapted to even the extremes. That is
simply a diverse and dynamic behavior, which we can only appreciate (yet hardly
understand). Why suddenly I am thinking about the origin and evolution process?
One part of the answer is, I most of the times do that. The other part of the
answer is, parasitism is the peak of all the survival strategies developed by
organisms with simple but precise design which could not have appeared at first
(as seen to be a resultant in Miller-Urey experiment) but it came as a living
style later in the process of evolution when life started establishing itself
on this planet. Life evolved, forming clumps, grouping together for protection,
gaining higher degree of organization, specializing according to the
environment... so on and so forth. But some of the forms did not care to
achieve all these things. They were smart and cunning. This goes to all the
parasites, although I hate your kind of living but have to admire your adaptive
capabilities. The parasite class has many species on the list. Worms, bugs,
many plant parasites, but smallest of all "THE VIRUSES". They sneak
through everything, unseen, unheard and without anybody's knowledge they just
make replicates (best example is some strains of Ebola virus, who do not even
show any symptoms after infecting). Theory behind any parasite doing what he is
doing is just that those genes wish to survive. We in general tend to think
that, "Huh, a parasite must be enjoying his life, without really working
hard, as seen against somebody like plant". Plants not only create food
for themselves but even for other life forms (that is really a noble job). But
this is not a case. Parasites do struggle and they really struggle hard. For
us, host parasite interactions are difficult to understand. But by simple logic
it is quite clear that a parasite has to adapt if a host tries to change. And
he has to do it every time, if he needs to survive.
Let’s think about viruses’ way of
living for a moment. He is precise to its host, because it needs a lot many
personality changes for him to enter a new species. Like in case of portability
of Avian-Swine-Human host of the flu viruses. These three hosts, must be having
different protein signature (receptors), but they found a way in which they can
bind to both forms or get transmitted from one species to another. This is an
amazing capacity. Viruses are simple coat proteins with some specific
structures to attach to host cells, and inside the capsid lies a simple strand
of DNA/RNA which needs to replicate. So he knows, that change in which protein
(attachment coat proteins) will make him species portable, and here is the
natural selection acting, which selects the one whose genome has changed in
such a way that only that protein has changed. Another thing with viruses is
that they have no machinery to do all the activities like carry out replication
on its own & carry out pathways which generally a normal cell can carry
out. It needs a lot of complexity in the system and energy regulation
techniques. Virus never seems to be concentrating on all those aspects. He rather
chooses to use somebody else's machinery for all such activities. Does this
ensure survival in a better way? Definitely yes, in case he is sure that life
will anyways exist on this planet, which will help him to propagate. But if
not, then what is he up to? Interesting...
Some time back when I questioned
in philosophical terms, what viruses are trying to do on earth, I instantly
replied saying that they are nature’s creation to make us aware that there are
tiny species out there that can halt us and nature is the decision maker. On
the other hand biologically speaking, Nature actually has nothing to prove here
(this is a common human trait), it need not rather. So it looks like, “LIFE”
just shows us that "there is another way it can propagate!”
