Osmotic stress and regulatory volume decrease in Crithidia fasciculataparasites

Abstract

Regulatory volume decrease (RVD) describes the response to hypoosmotic stress in many cells including the parasitic flagellate Crithidia fasciculata. Hypoosmotic stress causes initial swelling, the cell expels excess liquid and returns to a normal volume. This process is not able to withstand excessive osmotic stress. We use the MTT (3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyl‐2H‐tetrazolium bromide) Assay is used to assess cell viability, while microscopy images and spectroscopic light scatter used to follow changes in cell shape and size. It was found that after being placed in 70% hypotonic (30% isotonic) solution, cells did not recover from hypoosmotic stress. We are currently developing protocols for this little‐studied parasite and investigating the mechanisms of RVD in Crithidia fasciculata including the role of the osmoregulatory contractile vacuole.