Xref: utzoo sci.bio:1329 sci.astro:2378 sci.philosophy.tech:675
Path: utzoo!utgpu!water!watmath!clyde!att!ucbvax!husc6!bloom-beacon!athena.mit.edu!ayermish
From: ayermish@athena.mit.edu (Aimee Yermish)
Newsgroups: sci.bio,sci.astro,sci.philosophy.tech
Subject: Re: DNA for interstellar messages
Summary: oh, come on...
Keywords: realities of viruses
Message-ID: <6211@bloom-beacon.MIT.EDU>
Date: 14 Jul 88 23:57:29 GMT
References: <2743@bath63.ux63.bath.ac.uk> <2244@ur-tut.UUCP> <3916@ut-emx.UUCP>
Sender: daemon@bloom-beacon.MIT.EDU
Reply-To: ayermish@athena.mit.edu (Aimee Yermish)
Organization: Massachusetts Institute of Technology
Lines: 44

Besides the problems of not wanting to let loose a nasty evil killer
phage from hell on the nice friendly space aliens, there are some
realities that just don't make walkie-talkie-viruses the most
promising of methods.

1.  Why would you *want* to use DNA, which is not a particularly
obvious code, for communication with another planet?  Sagan squares
seem a lot more promising.  Remember that viruses are generally pretty
small and it's all they can do to contain their *own* coding
information, so huge quantities of interesting stuff are probably out
of the question.

2.  You're assuming that there are cells on the receiving planet that
can (a) be infected by the virus (tailspikes are pretty specific
enzymes, y'know) (b) replicate it (requires the presence of
machinery which can transcribe and translate the code, not to mention
the correct precursors) and (c) lyse it (probably the easiest step, if
you've gotten that far, but it still requires a susceptibility to
whatever protease the virus has).  Somehow I don't think that's a
terrific assumption to make.

3.  Unless you stuck the virus in some nice container, space vacuum
might well do nasty things to the virus.  But if you're sending a nice
container, why not put something more self-explanatory (like, say, a
picture) in it?

4.  Why send a single probe that moves slower than light and gets
stuck on asteroids and falls into stars and such when you can send a
electromagnetic radiation-type message?

5.  Speaking of electromagnetic radiation, there's an awful lot of it
out there in space with no atmosphere to protect you.  UV radiation
does bad things to DNA.  In particular, it dimerizes adjacent
thymidine residues, leaving you with something unreadable.  Here on
earth, the cells have evolved all sorts of complex mechanisms to find
and correct errors.  Viruses don't carry those mechanisms with them.

I'd think of some more, but I have to run.  Sorry to burst bubbles.

--Aimee
------------------------------------------------------------------
Aimee Yermish		ayermish@athena.mit.edu
MIT couldn't care less about anything I say. 
(as long as I finish that last paper...)