Re: Dinosaur osteocytes' preservation supported by molecular analysis

[David Marjanovic <david.marjanovic@gmx.at>]

Heh. Schweitzer presented it today. :-) Was pretty impressive.

> The discovery of soft,  transparent microstructures in dinosaur bone
> consistent in morphology with osteocytes was controversial.

The first half of the talk went into showing that they're indeed 
osteocytes and not a biofilm. Their filopodia are half as thin as most 
bacteria.

> We present immunological and  mass spectrometry evidence for
> preservation of proteins comprising extant osteocytes (Actin,
> Tubulin, PHEX, Histone H4) in osteocytes recovered from two non-avian
> dinosaurs.

Huh. Mass spectrometry wasn't mentioned today.
Actin and tubulin occur pretty much everywhere in eukaryotes. So does 
histone H4, but the point is that histones are specific to eukaryotes. 
PHEX is an enzyme that occurs only in osteocytes (not even their 
precursors, osteoblasts); the antibody they used to stain it is specific 
to avian PHEX and does not stain alligator osteocytes. It stains 
*Tyrannosaurus* and *Brachylophosaurus* osteocytes (the latter a little 
less strongly).

> Furthermore, antibodies to DNA  show localized binding to these
> microstructures, which also react positively with DNA intercalating
> stains propidium iodide (PI) and 4′,6′-diamidino-2-phenylindole
> dihydrochloride (DAPI).

As I got to point out in the questions session, all these things 
probably bind to tiny fragments of DNA or even isolated nucleobases. 
Schweitzer agreed that DNA that can't be sequenced is basically useless 
and that that may well be what she found there.

> We propose mechanisms for  preservation of cells and component
> molecules, and discuss implications for dinosaurian cellular
> biology.

No time for that in the talk.