[Nhcoll-l] Tissue subsampling scissors

Wed Jun 10 03:19:00 EDT 2015

Hi Andy,

as we only have -80°C storage but not cryo (liquid nitrogen storage), I 
cannot comment on the scissors performance per se, but perhaps add a 
thought on "contamination"

For us fish folks, but also for all people working with slimy, 
mucus-rich critters, the mucus (or body fluids in case of fresh 
[muscular] tissue samples) is probably No. 1 contaminant, which - 
however - may already sit inside your storage fluid and inside your tube 
because of original contamination issues in the field. Using the same 
scissors - even if you clean them you can't dry them completely, 
condensation on the cold scissors might add to this problem - and 
immerge the same instrument into a couple of fluid filled tubes seems to 
be the higher contamination risk. Therefore, we prefer to remove the 
tissue, putting it on a neutral surface (which is tossed away after 
usage) and to cut it preferably with a scalpel blade.

The second and much more immanent and critical contamination risk occurs 
during extraction (and thus is completely independent of tissue 
subsampling), especially when using extraction kits with silica-column 
systems that do have strongly foam building washing buffers. Normally, 
washing steps are done with larger volumes, and - working at plate scale 
- with an electronic multichannel pipette. I have seen folks that not 
only did not care about the sipping and supping foam building up inside 
and outside the wells, but wondering why they do have contaminations. 
The similar applies, if pipettes are shared in and among working groups 
with one person causing an undetected aerosol contamination inside the 
pipette.

If your tissue template used for extraction is sufficiently large, there 
should be no contamination issue (unless your the DNA of your template 
is completely degraded and/or the DNA yield fairly small), as the DNA of 
the template will always outnumber potential strains. But fluid transfer 
and contamination of DNA molecules dissolved to it may be the much 
higher risk.

Hope this helps even though it does not directly answer your original 
question.

Dirk

Am 09.06.2015 um 18:27 schrieb Bentley, Andrew Charles:
>
> Hi all
>
> I am interested in knowing what others are using for subsampling 
> tissues for tissue gift purposes in their cryo collections.  I know 
> some people use scalpel blades but I prefer fine dissection scissors 
> as they not only provide a finer manipulation but also (in most cases) 
> negate having to remove the tissue from the original tube an thus 
> avoid additional contamination possibilities.
>
> We have been having issues however with the regular dissection 
> scissors we have been using as frozen tissue (especially at cryo 
> temps) causes a large amount of wear and tear (both dulling and 
> bending) of these scissors. So, we are considering purchasing ceramic 
> coated tungsten carbide scissors such as these: 
> https://urldefense.proofpoint.com/v2/url?u=http-3A__www.medicalresources.com_shopping_proddisplay.asp-3Fcatalogid-3D18330&d=AwID-g&c=-dg2m7zWuuDZ0MUcV7Sdqw&r=CLFZJ3fvGSmDp7xK1dNZfh6uGV_h-8NVlo3fXNoRNzI&m=C7oi9eL59c5PGDdHf0MB3g3q4eUFmO9hdpkEx5BuH7I&s=OzMc0KqdMgsOSABtBmQTkAfi0Tp7LWoesxxDz5VVcdM&e=  
> <https://urldefense.proofpoint.com/v2/url?u=http-3A__www.medicalresources.com_shopping_proddisplay.asp-3Fcatalogid-3D18330&d=AwMFAw&c=-dg2m7zWuuDZ0MUcV7Sdqw&r=CLFZJ3fvGSmDp7xK1dNZfh6uGV_h-8NVlo3fXNoRNzI&m=YH6kgdVNvngaC4BvStezXfuEIUtApvrk-vEQfUz0Y1M&s=hvDxlayAy9zEc7ZCtwus8kvPYWZbParjjK-l_WuSmdw&e=> 
> – which are purported to be six times more durable than regular 
> stainless steel varieties.  They are however VERY expensive and so, 
> before diving in I thought I would ask around to see what others are 
> using.
>
> Any assistance would be greatly appreciated.
>
> Andy
>
>     A  :             A  :             A  :
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>     V                V                V
> Andy Bentley
> Ichthyology Collection Manager
> University of Kansas
> Biodiversity Institute
>
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