Immunofluorescence study of spindle microtubule arrangements during differential gonial mitosis of Acricotopus lucidus (Diptera, Chironomidae).

The changes in microtubule arrangements correlated with the behavior of the germ line limited and soma chromosomes were studied during the last unequal gonial mitosis, the so-called differential mitosis, of the chironomid Acricotopus lucidus by indirect immunofluorescence using a monoclonal anti-beta-tubulin antibody, and by simultaneous staining with the DNA-specific fluorescence dye DAPI. An impressive difference in microtubule density between both half spindles was determined in metaphase and during the monopolar anaphasic migration of the germ line limited chromosomes. In the following normal separation of the soma chromosomes, a similar microtubule density in both half spindles occurred. In each of the half spindles, chromosome movement and spindle elongation occurred independently, and in one half spindle two anaphasic chromosome movements ran off one after another, the second without a simultaneous spindle elongation.