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Re: Rconstructing DNA (was Re: Dino-fuzz found in amber?)

On Sun, Sep 18, 2011 at 3:53 AM, Tim Williams <tijawi@gmail.com> wrote:
>  What then? What can you do with it?  You'll never know if you're right, 
> because
> we're never going to find _T. rex_ DNA.

What you can do with *paleontology*? You never will find courtship
behaviours, colours of the most (oh wait!)...

The methodology is sound enough to molecular biologists use this
techniques and reconstitute ancestral sequences.

The rationale is basically the same as the morphological phylogenies.
We can infer that the most recent common ancestor of protostomes and
deuterostomes had bilateral simmetry. There are many characteristics
that are inferred for the Urbilateria.

Even for Cenancestor or LUCA.

Well lets take Crocodylus niloticus peptide fragment (NADH
dehydrogenase subunit 6, a mitochondrial protein), the first 10 aa
residues are: MNINRWLFST

And for Gallus sonneratii for the homologous protein fragment: MTFINRWLFS


It seems that a codon is missing in croc (or was inserted in Gallus evolution).

For the modified vertebrate mitochondrial genetic code we have for croc:
N -> AAT/C
I -> ATT/C
N -> AAT/C
R -> CGN
W -> TGA/G
F -> TTT/C
S -> TCN
T -> ACN

The G. sonnerati DNA sequence is: GTG ACC TTC ATC AAC CGA TGA CTA TTC TCA

So we see the seventh codon of C. niloticus it corresponds to the
eighth codon of G.sonnerati, which is CTA. So the croc codon probably
is CTN. And in the actual DNA sequence it is CTT.

And croc/bird split is much older than T-rex/bird split.


Roberto Takata