Mike O'Hara wrote:
> > Carrying on from the original question (are viruses alive) and looking at Mario Vaneechoutte's definition, how do people feel about 'alive' for the BSE agent. At this stage it looks to be a variant protein form that perpetuates its structure by altering non-variant forms (the ultimate in political conversions). One would have to suppose that the variant form arose in some way and has since perpetuated itself.
>Ed Rybicki wrote:
> For me, it's simple: it's not replicating; like fire, it is simply
> propagating a chemical reaction which varies according to its
> substrate; therefore, it is not alive.
Strange, according to the definition I favour: 'Life or living
information is that information which is capable of make more material
instantiations of itself by copying already existing instantiations of
itself', prions are alive. It came as a surprise that something else
than DNA-RNA could replicate on its own and by a completely different
mechanism, but prions fit the definition of 'life' I stick to.
All depends on the definition of course, still this one allows for a
clear cut between living and nonliving information.
Indeed, as Mike O'Hara points out: it is sufficient that an initial
instantiation somehow originates to start an instoppable proces: prions
keep transforming normal proteins into prion proteins. Compare to wrong
information (oral, printed, in the media, on the net): once it got
started, you can't withdraw it. Only a few copies can be abolished, but
the other copies keep going on copying. That's life. It's a cancer.
(Sorry if a similar posting reaches you. At the moment I can't see the
first one in the Newsgroup, so I try again).
PS. Maybe prions can be considered as a new form of life, which
originated much later than DNA-RNA-protein life, and which could exist
as a parasite on this predominant form of life. This is different than
DNA-RNA-protein parasitic species, which are derived from
Laboratory Bacteriology & Virology
Blok A, De Pintelaan 185
University Hospital Ghent
Belgium 9000 Ghent
Tel: +32 9 240 36 92
Fax: +32 9 240 36 59
E-mail: Mario.Vaneechoutte at rug.ac.be