molecular and radioactivity

[Hachey, John]

If you were to start up a molecular biology lab today, would you require
a setup for radioactive work? With all the various chromogenic, chemiluminescent and fluorogenic
detection reagents available today, is radioactivity extraneous? Any specific protocols
still absolutely requiring radioactivity?

Thanks, Curious John

[Emily A Breneman (breneman@Princeton.EDU)]

I think mRNA display is much easier when (if not impossible without) using radioactive isotopes.
Emily

[Cathal Garvey]

Hi John,
Speaking as a practising molecular biologist, I can think of no routinely
used procedure performed today involving radioactive molecules.

In fact, most if not all of the older hazardous reagents that were used a
decade ago are easily replaceable now. Many mutagenic compounds like EtBr
can be replaced with harmless and less cumbersome to manage alternatives,
though equipment used to visualise the results may need to be updated to
maintain resolution.

One use of Radioactivity that used to be commonplace was in-situ
hybridisations and protein or DNA blots, but these have been entirely
replaced with flourescent alternatives by now.

The only valid use of Radioactivity I've encountered that remains in
reasonably mainstream use is mutation breeding for plants or the like, but
even in this case one can use an X-ray machine instead of a radioactive
source.

I hope this helped! If you have questions about replacing particular
reagents or protocols with less radioactive alternatives, I'd be happy to
help look it up for you.
-Cathal Garvey

[Michael Sullivan]

Although I don't use radioactivity often, there are still a few
procedures where I do or would choose to use it.

For blotting/hybridization procedures, I would still choose
radioactivity, hands down. As far as I know, most non-radioactive
detection procedures require an immunoblot-like detection step. In my
opinion, this just adds one more additional set of steps that needs
to be optimized and opportunity for noise or background to be
introduced inot the experiment. When might one want to do some type
of hybridization experiment? A conventional library screen (I've done
one of these in the last 2 years), outhern bolt to determination of
the number of loci for a transgenic event, or looking at whether
there are multiple classes of transcripts corresponding to a given
gene. For the latter, if one wants quantitative data, radioactivity
is linear over several orders of magnitude while most non-radioactive
detection systems have a far more limited linear range.

Of course there are many biochemistry experiments that are most
easily done with radioactivity, but this will be largely dependent on
exactly what you are working on. I may be facing doing kinetics on a
methyl transferase soon. From my perusal of the literature, this
looks like it will be much simpler to do with radioactivity than by
any other approach.

Mike

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[WS]

Well said, Dima!

When designing a lab from scratch, it makes very well sense to include
instrumentation and space for radioactive isotope work. To add it
later, it might require a lot more of paperwork and construction (and
therefore money and time).

Wo