| The ultrastructure, protein composition and cytoskeleton of Stylonychia curvata in Hypotrich ciliate were determined by use of sanning electron microscopy, transmission electron microscopy(TEM), as well as SDS-PAGE; The phylogenetic relationship and molecular genetic character of hypotrich ciliates, including Stylonychia mytilus and Tachysoma pellionella in Oxytrichidae, Urostyla grandis in Urostylidae, Euplotes encysticus in Euplotidae, Pseudokeronopsis rubra in Holostichidae, as well as three species of cysts. The result is as follows:1. The ultrastructure and protein composition of Stylonychia curvata(1) The ultrastructure of Stylonychia curvata: The ultrastructure of Stylonychia curvata is similar to that of the ciliate in Oxytrichidae. By use of selective extraction, together with diethylene glycoldisterate (DGD) embedment-free section TEM, the structure of intermediate filament-lamina-nuclear matrix (IF-LA-NM) was observed: the network display inconsistent in different regions, of which, the compact part is mainly composed of intermediate filament or filament ribbons about 10-30nm in diameter, whereas the sparse part is largely composed of filament lOnm in diameter. Compared with that in cytoplasm, the network in nucleus is rather densely arranged. The thin-layer-like LA is about 50nm in thickness, whose filaments connect with IF in cytoplasm and with NM in nucleus respectively.(2) Comparison of protein component between vegetative cells and resting cells: Compared with vegetative cells, the resting cells of Stylonychia curvata preserve some part of the protein bands:95.3, 82.9, 77.2, 65.7, 62.3, 58.3, 48.6, 40.4, 37.2, 35.2, 31.0, 25.1, 18.4, 16.3kD, whereas lost some protein bands, meanwhile, produce some new particular proteins: 70.1, 56.3, 46.2, 28.2, 26.2, 24.2, 22.2kD. The result shows that the protein composition has changed notably in the course of kinetosome-resorbing cyst formation.(3) Conclusion: The intermediate filament-lamina-nuclear matrix (IF-LA-NM) exist in the Stylonychia curvata, which is composed of filament about 10nm in diameter. Compared with vegetative cells, the protein component of resting cells have been greatly changed. 2. Phylogenetic relationship of hypotrich ciliate(1) Phylogenetic relationship of vegetative cells of hypotrich ciliate: The phylogenetic tree was constructed using the neighbor-joining (NJ) method and maximum-parsimony (MP) method after the small subunit ribosomal RNA (SSrRNA) gene for four species of hypotrich ciliate and three species of resting cells were sequenced, and aligned, the result suggested that: there were two branching lineages, in one of which both Euplotes encysticus and Aspidisca steinii diverge first from the main line and share closer relationship with each other than with other species with strong bootstrap support (90% [NJ]); in the other, the Diophrys appendiculata, Uronychia transfuga, Pseudokeronopsis rubra, Urostyla grandis separated orderly from the hypotrich line. Furthermore, the trees also supported that two groups including Sterkiella nova and Onychodromus quadricomutus, as well as Stylonychia mytilus and Paraurostyla weissei were closely related with strong bootstrap support(99%[NJ], 97%[MP] and 40%[NJ], 74%[MP] respectively). Therefore, the molecular data cast light on that Euplotidae might separate earlier than other species of hypotrich ciliate.,(2)Comparative analysis on molecular characters among resting cellss in hypotrich ciliate: With the reference of vegetative cellss, the nucleotide composition, locations in codon, evolutionary distance, standard error, Transitional and Transversional rate of SSrRNA of three species of resting cellss coming from Urostyla grandis, Euplotes encysticus and Tachysoma pellionella were determined using the method of Kimura two-parameter correction model. The result is as follows:Evolutionary distance: The evolutionary distance of vegetative cellss and resting cellss between Urostyla grandis and Euplotes encysticus is 0.162 and 0.170 respectively, this reveals that the genetic...
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