[Histonet] oysters larvae again

[John A. Kiernan]

Anne Sophie's MEMPFA-T fixative (0,1 M Mops pH
7,4; 2 mM EGTA; 1 mM MgSO4; 4% paraformaldehyde;
0,1% Tween 20) does contain EGTA, which chelates
calcium ions, but 2mm seems intuitively to be very
weak. Are the shells of oyster larvae extremely
thin?

I've not come across this MEMPFA-T fixative
before. Could anyone provide a reference for it?

-- 
-------------------------------
John A. Kiernan
Department of Anatomy and Cell Biology
The University of Western Ontario
London,   Canada   N6A 5C1
   kiernan[AT]uwo.ca
   http://publish.uwo.ca/~jkiernan/
   http://instruct.uwo.ca/anatomy/530/index.htm
_______________________________
"Monfils, Paul" wrote:
> 
> I don't have a background in ISH, so I can't offer an opinion on the best
> fixative for that purpose.
> 
> Regarding your second question, while I'm not familiar with either fixative,
> I can see that the Davidson fixative, containing 10% acetic acid and no
> buffers, would decalcify (dissolve) larval oyster shells.  But the MEMPFA-T
> appears to be made up in pH 7.4 buffer, in which case I don't see how it
> would decalcify. In any case, I am wondering why you are using a
> formaldehyde-based fixative for TEM?  Ordinarily a glutaraldehyde-based
> fixative would be preferable for TEM.
> 
> > ----------
> > From:         histonet-bounces <@t> lists.utsouthwestern.edu on behalf of
> > Anne-Sophie MARTINEZ
> > Sent:         Tuesday, March 21, 2006 5:13 AM
> > To:   histonet <@t> lists.utsouthwestern.edu
> > Subject:      [Histonet] oysters larvae again
> >
> > Hello,
> > (1) I plan to fix oysters larvae/juveniles (4 month) for in toto ISH.
> > Which fixative is the best : Davidson (10% formaldehyde 37-40%, 30%
> > ethanol 95%, 60% seawater, 10% acetic acid) or MEMPFA-T (0,1 M Mops pH
> > 7,4; 2 mM EGTA; 1 mM MgSO4; 4% paraformaldehyde; 0,1% Tween 20)?
> > (2) Would it be possible to use the MEMPFA-T to fix and "decalcify" the
> > shelves of the juveniles for TEM (embedding in type lowyril, unicril,
> > LR-white resins) instead of classical fixative (4% PFA) and then EDTA?
> > Thank you very much again.
> > Anne-Sophie
> >
> >