X-Message-Number: 9455
Date: Sat, 11 Apr 1998 13:47:49 -0700 (PDT)
From: Doug Skrecky <>
Subject: dmso improves fixation

  Fassel TA.  Sohnle PG.  Kushnaryov VM.
  Department of Microbiology, Medical College of Wisconsin, Milwaukee 53226,
  The use of dimethylsulfoxide for fixation of yeasts for electron microscopy.
  Biotechnic & Histochemistry.  72(5):268-72, 1997 Sep.
  Conventional methods of chemical fixation are often inadequate for preserving
  yeast ultrastructure. The thick cell wall severely limits penetration of
  fixatives rendering poor detail of the cell wall, membranes, and overall
  anatomy. Dimethylsulfoxide (DMSO) enhances penetration of
  chemicals and has been added to fixatives to improve cell preservation. At
  high concentrations (5 to 50%), however, it affects ultrastructure
  unpredictably. We found that adding 0.1% DMSO to fixatives
  greatly improved retention of yeast ultrastructure. Candida albicans, C.
  glabrata and Aspergillus fumigatus were fixed for 3 hr in 3%
  paraformaldehyde, 1% glutaraldehyde, 1 mM MgCl2, 1 mM CaCl2, 0.1%
  DMSO in 0.1 M sodium cacodylate buffer followed by 1% OsO4,
  1% K2Cr2O7, 0.85% NaCl, 0.1% DMSO in the same buffer. Thin
  epoxy sections were post-stained in uranyl acetate and lead citrate. The
  multilayered character of the cell wall was distinct and well structured.
  Addition of ruthenium red or alcian blue to the fixatives further enhanced
  the outer fibrillar layer. The plasma membrane was contiguous and tightly
  adjacent to the inner mannoprotein layer of the cell wall. The cytoplasm was
  well preserved and the overall preservation of the yeast ultrastructure was
  significantly improved.

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