[bio.dros] Immuno on embryos-update

[ITO, Kei]

>3)  Ni2+ can increase background.  Avoid if possible.

Another problem of using Ni2+ is fading. Ni-containing Black DAB 
staining tends to fades faster than brown staining without Ni. 
After five years, Black staining may have gone away (depending 
on the mounting procedure). And sometimes you DO want to 
re-examine your preps five years later.

Also, if you want to post-fix (after DAB reaction) the specimen 
with glutaraldehyde, avoid using Ni2+. The staining may go away 
quickly during this procedure.

Kei