Like many labs we do imaging at ~37 degrees when working with live
tissue.  We heat our objective lens and have heated cell/slice
chambers to hold the samples.  I am uncertain whether 70 degrees would
exceed the safe maximum for an objective lens or not.  The biggest
issue is if the high temperature would break the seals on the
objective.  If you are using oil or water dipping lenses this would
damage the lens.  Also, would the high temperature alter the optical
performance of the lens?  Is this something you could compensate for,
for instance adjusting a correction collar?  Another issue is that
physical stress on a lens (due to thermal expansion of dissimilar
materials) can induce birefringence effects in the lens which can
cause issues if you are using polarized light sources.
Temperature cycling lenses can also be a problem.  The lens we keep at
~37 degrees is kept heated all the time.  Cycling between room
temperature and 37 degrees every experiment is hard on the seals.  We
have found that just keeping the lens at a constant temperature is
better for the health of the lens.
The objective and microscope manufacturer should be able to help
answer these questions.  One way to sidestep these issues would be to
use a non-contact air lens, although this would greatly limit your
lens NA and resolution.

I hope this helps!

Craig


On Sun, Sep 27, 2009 at 10:34 PM, Graham Wright
<[log in to unmask]> wrote:
> Hello,
>
> The bacteria in question would want to be at 70 'C. I'm interested whether
> there are any FPs that will, in theory, work at such temperatures. I am also
> interested whether there are any microscopes and objectives that can operate
> and withstand such temperatures to enable live cell imaging.
>
> It's just an idea for now, but one we're interested to know whether it's
> possible or not.
>
> Thanks,
> Graham
>
>
> 2009/9/26 Craig Brideau <[log in to unmask]>
>>
>> How elevated are the temperatures?  Do you have a microscope and/or
>> objective lens that will work at these elevated temperatures?
>>
>> Craig
>>
>>
>> On Fri, Sep 25, 2009 at 2:53 AM, Graham Wright
>> <[log in to unmask]> wrote:
>> > Dear list,
>> >
>> > I have been asked an interesting question by a colleague about what the
>> > highest temperature at which one can do fluorescence time-lapse imaging
>> > as
>> > well as if there are thermostable fluorescent proteins to work with at
>> > elevated temperatures. Also, does anyone know of fluorescence microscopy
>> > work with Archaebacteria?
>> >
>> > Thanks for the help,
>> >
>> > Graham Wright
>> >
>
>