Contamination in SH-SY5Y cultures, mycoplasma? - (Jun/02/2010 )

Anyone with experience of mycoplasma- (or other bacteria-) infection of SH-SY5Y cells? How did the cells look and react to that?

I have a contamination in my cultures which shows as a lot of black dots in the cells cytoplasm. In some dishes, also the media contains moving black dots. It also seems as the cells are growing at a slower rate than usual. Could this be mycoplasma? If so, I would not be able to see the bacteria as black dots in the microscope would I? I have tried to grow the bacteria on blood-agar plates but no colonies showed after 4 days. Gram-staining of pellet from the contaminated media did no show any distinct bacteria. I have also tried to throw away everything (cells, media, serum etc) and start with freshly thawed cells and new solutions but the black dots came back after a few days. What could this possibly be?

S

Cell debris? It is unlikely to be mycoplasma if you can see it. The black dots in the cytoplasm may be mitochondria or other sub-cellular structure, especially if the cells are nearing confluence/ have been cultured a lot.

It is probably not cell debris, because the black dots even show in dishes with only culture media (without any cells) after 3-4 days in the incubator. Also, the dots in the cytoplasm seems to be moving around..