Counting Choanos

From ChoanoWiki

Counting choanos using the hemocytometer

The hemocytometer lets you figure out how many cells there are in a given volume. The bright round things are choanos. The dark spots are bacteria.

1. Scrape cells.
   • If cells were not very dense, take 1 ml of culture to count.
   • If the cells were very dense, dilute 100 µl of culture into 900 µl media
2. Add ~ 1 µl formaldehyde to the 1 ml of cells. This kills the choanos so they won’t swim around while you are trying to count them.
3. Clean the hemocytometer with a kimwipe. Place the coverslip on top of the hemocytometer.
4. Make sure the choanos are resuspended by inverting the tube. Put 10 µl of the choano suspension onto the hemocytometer.
5. On the microscope, count 4 (4 x 4) squares and take the average as your “square count”. (Can also just count one square for a less precise count).
6. Figure out many choanos/ml:

choanos/ml = (square count) (10⁴) (dilution factor, if applicable)