Fellow zincologists:
I have been sent some of your postings. You seem to have it about right about zinc.
TSQ (Frederickson et al., J Neurosci Meth, 1987) and it's more recent congeners, zinquin and TFLZn (365:405) are the only cell-permeant zinc-specific indicators available. Newport Green (488:5156) is fair, but has a very high Kd, (10exp-6) and thus only shows high concentrations, as seen during zinc release in neurons and beta cells, and so forth (e.g., Weiss and Sensi, TINS, 2001; Li et al., J Neurophysiol, in press; Soc Neurosci Abs, 2000, 2001).Unfortunately, niether the quinolines nor Newport Green is ratiometric. Also: the lipophilic quinolines will stain zinc in synaptic vesicles, whereas the "trappable" dyes will not, due to their metabolism in the cytosol.Thus Newport Green and TSQ derivatives give completely different staining with live tissue in vitro or in vivo.
Fixed tissue cannot be stained for zinc, period. Neither can tissue that has "autofixed" by simply sitting at room temperaturee 12 hours post-mortem.
See the silver (AMG) methods of Danscher (there is only one "Danscher") for histologic staining of weakly-bound or aquozinc in situ for LM or EM.
By the way, TefLabs in Austin (www.teflabs.com) is a great source for TSQ, TFLZn and ZinQuin.. Akwasi Minta, who originally made the TSQ for us at Molecular Probes is now CEO at Teflabs.
The only ratioable probe for zinc that I know of that is not calcium-magnesium sensitive is the apo-carbonic anyhdrase +ABDN system that Thompson, Fierke and I developed (Thompson et al., J Neurosci Meth, 2000; SPIE 2001; J Neurosci Abs, 2000), which can be used from 1 pM to 10 uM, in either the affinity or the percent-saturation modes. We can supply you with that indicator, but is is NOT membrane permeant.
There will be a session on this topic at the meeting "Zinc Signals 2002," (www.caymanconferences.com) next Spring in Grand Cayman. Please come listen to all of the zinc measurement folks as they tout their wares.
Let me know how it turns out:
Keep on zincin'
Chris Frederickson
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