Chlamydomonas - mutants with no cell wall attachment

Video at normal (1x) speed.

I sampled a very small number of Chlamydomonas and placed them into a petri dish under continuous light. Now two months have passed. They appear to mostly be mutants with no adherence of the cell membrane to the cell wall. Some unequally sized cells appear to be attached, likely indicating anisogamy, as dividing cells typically are all equally-sized and divide a fixed number of times.

At the end of the video I apply a very salty solution to the slide to see how they react. The plasma membranes shrivel up while the cell walls remain the same, and motility decreases substantially. After the recording, some continued to swim around despite the hostile conditions. By an hour later, many were swimming again and their plasma membranes had expanded back to their previous position.

Chlamydomonas are capable of maintaining osmotic balance in hyperosmotic shock with both contractile vacuoles and by producing glycerol to balance the osmotic pressure across their plasma membrane. They are very closely related to Dunaliella, which lack a cell wall entirely and have no contractile vacuole, relying instead entirely on glycerol to passively maintain osmotic balance, likely beneficial for their habitat of hypersaline conditions.

I will culture a subset of these Chlamydomonas in saline conditions by gradually increasing their salinity to see if they adopt a similar strategy and eliminate the cell wall entirely.