Tissue culture media sterility testing

Test Compounds. Nickel subsulfide (crystalline oNi3S2, particle size < 5 ym) was provided by Dr. Edward Kostiner, University of Connecticut, and its purity and crystal structure were verified by emission spectroscopy and X-ray diffractometry as previously described (L5 - Amorphous nickel monosulfide (NiS) was precipitated by addition of aimnonium sulfide to a solution of NiCl2 that was prepared from carbonyl-derived Ni dust and ultrapure HCl. The amorphous NiS was devoid of crystal structure, based upon X-ray diffractometry. The aNi3 2 and NiS powders were sterilized by washing in acetone immediately prior to suspension in tissue culture medium. 

Fertilization medium (FM) All chemicals should be Sigma-Aldrich tissue culture or embryo-tested grade. Prepare the following concentrated stocks and filto each through a 0.4- jm MiUipore filter into a sterile plastic tube. Store frozen at -20 C. 

Cells to be tested are grown in a tissue culture dish (not a flask, which would be difficult to scrape) until confluent. Most of the growth medium is removed, and an artificial linear wound is made in the monolayer, by using, e.g. a sterile pipet tip, or a rubber policeman . Care has to be taken to clean all the wounded area from cells, because in case an uneven scraper is used, which leaves behind some attached cells, their presence at the end of the experiment may complicate the interpretation of the results. The plate is then rinsed several times with PBS to remove all the debris, and the test medium (containing dilutions of the supposed migration-... 

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