ASSEMBLY AND FUNCTION OF CHLAMYDOMONAS FLAGELLAR MASTIGONEMES AS PROBED WITH A MONOCLONAL-ANTIBODY

Mastigonemes are hair-like projections on the flagella of various kind s of lower eukaryotes. We obtained a monoclonal antibody (mAb-MAST1) t o mastigonemes of Chlamydomonas reinhnrdtii, and found that it reacts with a single flagellar glycoprotein of about 230 kDa. Interestingly, immunofluorescence microscopy demonstrated that mAb-MAST1 recognizes n ot only the flagellar mastigonemes but also a ring composed of 10 or m ore particles located in the anterior end of the cell body close to th e flagellar bases, The ring structure may be the pool of the mastigone me protein, When the flagella are amputated, they regenerate to their original length in 90-120 minutes, We found that mastigonemes appear o n the new flagellar surface as early as 15 minutes after deflagellatio n, and that new mastigonemes are mostly assembled onto the distal regi on of the flagellar surface. Mastigonemes thus appear to be inserted i nto the membrane only in the distal region of the flagellum, Alternati vely, mastigonemes may be inserted at the base and transported very ra pidly to the distal portion where they are trapped, When live cells ar e treated with mAb-MAST1, mastigonemes disappear from the flagellar su rface, In these mAb-MAST1 treated cells, the swimming velocity decreas es to 70-80% of the normal value, although the flagellar beat frequenc y increases to similar to 110% of the control, These findings demonstr ate vectorial transport of mastigonemes to their assembly sites, and s how that mastigonemes function to increase flagellar propulsive force by increasing the effective surface of the flagellum.