title: Participation of calcium in flagellar shortening and regeneration in Chlamydomonas reinhardii.
abstract: Cation chelators cause flagellar shortening in Chlamydomonas reinhardii. Most effective are EDTA and EGTA (1 mM) but pyrophosphate (10 mM) also is effective. Addition of 5 mM Ca2+ after shortening caused by 4 mM EGTA results in flagellar regeneration. Other divalent cations can replace Ca2+ with the following relative activities: Ca2+ greater than Sr2+ = Mn2+ much greater than Ba2+ = Mg2+. Although the specific ion requirement to reverse shortening is not clear, it is possible that all of the ions act by displacing one bound cation, presumably Ca2+. A specific requirement for Ca2+ in flagellar regeneration could be demonstrated, however, because as little as 50 microM EGTA in the presence of 500 microM Mg2+ delayed regeneration and prevented full regeneration. Ca2+ at 100 microM overcame this inhibition.
mesh_terms: D002118:Calcium / Q000502:physiology*; D002413:Cations, Divalent / Q000494:pharmacology; D002614:Chelating Agents / Q000494:pharmacology; D002696:Chlamydomonas / Q000502:physiology*; D011756:Diphosphates / Q000494:pharmacology; D005407:Flagella / Q000187:drug effects / Q000502:physiology*; D012038:Regeneration / Q000187:drug effects*
chemical_list: D002413:Cations, Divalent; D002614:Chelating Agents; D011756:Diphosphates; C003319:sodium pyrophosphate; D002118:Calcium