Over the past two weeks I have been roundly rebuffed by members of this
newsgroup for the use of the phrase 'ancient gene(s)'. This treatment
went so far as belittling when a well known individual stated:
14 June, 1997 (private response)
"...Your question implies that you view evolution as a ladder... ...I
didn't respond publicly because there seems to be no point in
embarrassing you. Unfortunately, some others may not be so considerate
and you can expect some flames. If you're lucky the regulars will simply
ignore you."
15 June, 1997 (private response to my response)
"...[These] newsgroups are intended for professionals...to discuss the
hard-core science... ...There are other newsgroups for novices...you
should keep out if you are not in the field..."
My feeling is that this individual, along with others, was well
intentioned; however, I believe that my post has exposed a gap between
current thinking and dogma.
After reviewing the literature that I was directed to by the *only*
positive response I received to my original post (Bernot, 11 June, 1997,
this newsgroup), I hold the opinion that the responses I received stating
that 'there are no ancient genes' are dogmatic and reactionary. The
problem, as I see it, stems from a lack of distinction between the use of
'gene' verses 'gene sequence'.
My position is born out by the simple fact that a set of orthologous and
nonorthologous-displaced genes minimally required for cellular life can
be identified between species and taxa (Mushegian and Koonin, 1996, PNAS
93:10268; Clayton et al., 1997, Nature 387:459); moreover, in a news
article, the term 'modern gene' is used, directly implying 'ancient
genes' (Pennisi, 1996, Science 272:1098). However, this does not imply
that the gene sequences are ancient because a myriad of mechanisms could
be used to explain convergent sequence evolution between species over the
past 3+ billion years.
So, in the light of the literature, I have redirected my query:
Of the proposed gene set minimally required for cellular life
(http://www.ncbi.nlm.nih.gov goto NCBI Research/research projects goto
Genome Analysis/comprehensive analysis of complete genomes), what
evidence or *opinion* exists concerning which gene(s) can be considered
to be the most ancient (ie. can the minimal gene set required for
cellular life be pared down to a likely pre-cellular set)?
On the other hand, in my original post I asked for the most ancient
extant organism, I'll accept the criticism that this phrasing is a bit
understated.
What I'm after is an extant bacterial species or group that demonstrates
phenotypic/behavioral characteristics similar to those that can be
identified in the fossil record as the most ancient cellular life forms
(eg. Cyanobacteria and stromatolites).
S.Higgins
SUNY Health Science Center
