Metabacteria

[B.J.Tindall]

Ken,
To which my answer is, if the Archaebacteria/Archaea/Metabacteria are the
ancestors of the eukaryotes why don't eukaryotes have isoprenoid ether
linked lipids? Secondly the stereo chemistry of the lipids in eubacteria +
eukarya is different to that in Archaebacteria/Archaea/Metabacteria. Yoshe
Koga's group have shown that one of the key enzymes in the synthesis of the
isoprenoid ether linked lipids vs the synthesis of ester linked lipids is
not only stereospecific, but the two enzymes probably share not common
evolutionary origin. Thirdly the properties of the acyl vs isoprenoid based
memberanes are significantly different. Most people are either not aware of
that or simply sweep these facts under the carpet.....

With respect to the website you quote I would agree with problems listed
with respect to the alignment of the 16S rDNA and 18S rDNA sequences.
Unfortunately there are also fine structural differences between the
ribosome of the Archaebacteria/Archaea/Metabacteria, the
Bacteria/Eubacteria, and Eukaryotes. One of the key issues which are also
indirectly raised is the origin of life - rooting of all life. Essentially
I see no way of proving this unambiguously.

Brian


At 16:45 16.03.06 -0600, you wrote:
>Dear All,
>      I just happened to stumble upon this internet site by Dr. Hori of
Japan.  He and Dr. Osawa proposed the name Metabacteria to replace the
inaccurate name Archaebacteria.  This was many years before the really
horrible name Archaea was proposed in 1990 (as part of the Three Domain
classification, a warmed-over version of the discredited Three Urkingdom
classification).  The only logical choice is between Archaebacteria and
Metabacteria.  The name Archaea should NOT be used (well, except for the
spider genus Archaea).  I still prefer the name Metabacteria, rather than
Archaebacteria.  Then maybe it would dissuade those who still use
metabacteria as an outgroup in eubacterial phylogenetic analyses (which is
why thermophilic bacteria are artificially pulled to the base of
eubacterial trees).  Anyway, I'm glad to see Hori and Osawa haven't given
up on getting their name Metabacteria recognized and used, as well as due
credit for their early recognition that metabacteria ("arc
> haebacteria") are the bacteria closest to the origins of the eukaryotic
host cell:
>
>http://www.bio.nagoya-u.ac.jp/~hori/archaea.html
>


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