>On Wed, 2 Aug 1995 19:12:14 -0600, Andrea Elberger wrote:
>
>>In a recent posting to the confocal group, Guy Cox stated that DiI migrates
>>along the myelin to label neurons beautifully.  To clarify this, DiI migrates
>>within the lipid bilayer but yes, it does label neurons beautifully.  It has
>>been used to stain cells in culture, and does not appear to have any toxic
>>effects. DiI migrates along the cell membrane long before myelin appears and
>>after myelination, the dye still migrates continually along the membrane.
>>ANDREA ELBERGER   [log in to unmask]                    optf
 
and Ian Gibbins wrote:
 
>It's also worth noting that DiI is transported very well by living neurons
>following an injection of solution or the application of crystals into the
>terminal fields. In this case the transport is very rapid, and presumably
>is due to fast axonal transport of small particles of dye, which end up
>being concentrated  in perinuclear lysosomes or something similar.
>Different forms of DiI and its relatives work with varying degrees of
>success depending on the application...
>
 
Andrea is of course quite right it partitions into any lipid bilayer so will
label the membrane of a non-myelinated nerve or any other cell - it's just
that myelin represents a whole lot of bilayer.
 
I also agree with Ian about the speed of transport but I'm not sure about
the mechanism - I think it just spreads along the bilayer, though of course
any membrane cycling would also spread it.  But I'm pretty sure it's always
in the lipid phase.
 
Gavin Dixon used to get some of the finest 3-D nerve images I've ever
seen using the technique of touching a crystal to one point and thus lighting
up just those neurons which reached that spot.  Do you read this list,
Gavin?  If so perhaps you can share some tips.
 
                                                Guy Cox
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