[3dem] Biological TEM Standards

[David Gene Morgan]

Hi,

	Just to jump back in, I fully agree with Reinhard about the value of 
preparing the sample yourself.

	Another issue with grids of negatively stained catalase is that they 
don't age well.  A freshly made grid with freshly prepared crystals will 
show multiple orders of diffraction from the stained crystals either in 
electron diffraction mode or when looking at the Fourier transforms of 
images of the stained crystals.  As time goes by (and especially if the 
grids are not stored under constant temperature and humidity), the 
number of diffraction orders that are visible will decrease.  In my 
experience, purchased grids with negatively stained catalase are never 
as good as ones I have made myself, and often only show one or maybe two 
diffraction orders when they arrive from the manufacturer.

	One other thing that preparing the crystals yourself allows is you can 
do things like glucose embedding, standard freezing for cryoTEM, etc. 
If you purchase a prepared grid, you only get the stained crystals, and 
you can teach so much more if your students can prepare the same sample 
multiple ways.

On 10/15/2014 10:46 AM, Reinhard Rachel wrote:
>>>> 15.10.2014 um 16:36:
>> This may not be clear from David's message, but you can buy already prepared
>
>> TEM grids of negatively stained catalase from at least two sources: Ted
> Pella
>> and Electron Microscopy Sciences.
>
> this might be true - but this "eliminates" one important step - the sample
> preparation.
> Personally, I will always try to have this step included in teaching or
> demonstrating EM to the 'un-experienced' - it is so important; it is one of the
> key steps. - Even a 'not optimally' prepared biological sample is valuable for
> teaching, and for explaining the difficulties.
> kind regards,
> Reinhard
>


-- 
                  David Gene Morgan
              Electron Microscopy Center
                   047D Simon Hall
                   IU Bloomington
                812 856 1457 (office)
                812 856 3221 (3200)
             http://bio.indiana.edu/~cryo