| Abstract: | Cortical features were analyzed in successive samples of continuously growing stock cultures of amicronucleate strains GL-C and GL-I, and in micronucleate strain WH-6 (syngen 1, mating type I). Thirteen successive samples of strain GL-C, representing a time span of 111 months, 5 samples of WH-6 (43 months) and 2 samples of GL-I (1 month) were examined. The observed range of commonly expressed ciliary row numbers (corticotypes) was 16–20 rows in strain GL-C, 15–20 in strain GL-I, and 16–20 in strain WH-6. These ranges remained constant through time within each strain. The individual samples each included all or a large part of the total range observed in the strain, but the relative abundances of different corticotypes within this range shifted through time. The shifts appeared random, with no discernible trends. Mean contractile vacuole pore (CVP) position and number of CVP meridians were assayed in the 2 “GL” strains. Mean CVP position was an apparently stable character, with only slight fluctuations through time, while the distribution of number of CVP meridians was somewhat less constant. The CVP parameters of strains GL-C and GL-I were considerably different, and both of these strains were very different from the GL strain which had been studied by Nanney. In fact, these 3 “GL” strains have, among them, virtually the entire gamut of known CVP characteristics. The possible significance of these wide differences among strains presumed to be closely related is considered in the Discussion. |
