Studies over the last thirty-five years have learned much about dynein. More important, these past studies have provided intriguing glimpses of what information is yet to come. The ciliated protozoa, including Tetrahymena from which dynein was first isolated, will continue to be valuable in the analysis of dynein structure and isoform function.
Paramecium tetraurelia d4-SL4, a mutant derived from wild-type stock 51, possesses a clonal life span about one tenth that of the parental stock. The putative gene(s) that specifies the short life span does not seem to be a house-keeping gene. Assuming that life span-related changes are related to the prevalence of particular mRNAs, we searched for genes preferentially expressed in either young wild-type stocks or the mutant stock using the differential display strategy. A total of four cDNA clones showing such altered gene expression were isolated, three of which were expressed predominantly in the mutant stock. All of the genes were likely to be novel ones. Northern blot analysis revealed significant changes in the level of transcription of these genes with increased culture age.
The marine ciliate Anigsteinia candida (Yagiu and Shigenaka, 1956) Isquith and Repak, 1974 has been redescribed and recorded from the Arabian Gulf for the first time since the original discovery from Hiroshima Bay in Japan. More detailed observarions and morphometric analysis of the Saudi population have been included, which matches in many aspects those of the Japanese population. It measures about 400 × 60 μm with an average length/width ratio of 7.3 : 1 (414 × 56 μm, ratio 7.5 : 1 for the original description); the 24-30 ciliary rows were found to be within the range of the Japanese population (22-27 rows); the 200-260 spherical to ellipsoidal beads of the macronucleus were also within the range of 181-287 in the Japanese population. The faintly yellowish cortical granules were found to be the only morphological difference from the originally described colorless granules.