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From: michaelm@bcsaic.UUCP (michael b maxwell)
Newsgroups: net.bio
Subject: Re: Protein synthesis in red blood cells
Message-ID: <379@bcsaic.UUCP>
Date: Fri, 15-Nov-85 17:41:20 EST
Article-I.D.: bcsaic.379
Posted: Fri Nov 15 17:41:20 1985
Date-Received: Mon, 18-Nov-85 07:29:34 EST
References: <371@bcsaic.UUCP> <1414@mtgzz.UUCP>
Reply-To: michaelm@bcsaic.UUCP (michael b maxwell)
Organization: Boeing Computer Services AI Center, Seattle
Lines: 24

In article <1414@mtgzz.UUCP> jak@mtgzz.UUCP (j.a.kushner) writes:
>Now the mature adult erythrocyte is ready to leave the marrow and circulate 
>as a 'bag of hemoglobin' transferring O2 and CO2 between the lungs and the 
>tissues, and also acting to buffer the blood...without the nucleus, there 
>can be no further protein synthesis.  Not only is hemoglobin production 
>shut-off, but other vital enzymes can no longer be synthesized...
>In so doing, the lifespan of the rbc is decreased...

Interesting!  I realize it's only a matter of definition, but it almost
seems that the cell dies when it extrudes its nucleus (or as its
remaining mRNA disappears), since it can't synthesize anything else.
Its capicity for responding to the environment would seem to be at about the
same level as that of a buffer (in the chemical sense)--it can
chemically store O2 and release it, but not much more...  If viruses are
non-living because they don't have any protein synthesis machinery of
their own (definition, I know), it would seem that erythrocytes are too.
Incidently, what is the selective advantage of not having a nucleus in
one's RBCs?  Do they fit through smaller capillaries?  (But so do white blood
cells!)  And what happens to the ribosomes etc., which would seem to be
superfluous now?
-- 
Mike Maxwell
Boeing Artificial Intelligence Center
	...uw-beaver!uw-june!bcsaic!michaelm