Micro- & Ultrastructural Observations On The Cortical Microtubules And Cytopasmic Organelles Of Soil Ciliate Cyrtohymena Australis (Hypotrichida, Cliophora)

Hypotrich ciliates are the highest level taxa of protozoa. Cyrtohymena australis is one of soil ciliates which belongs to Cyrtohymena, Oxytrichidae, Sporadotrichina. Now the study is limited to the observation about microstructure in few ciliates, we know less about ultrastructure, the function and the change about components of ciliature microtubulin between cyst and vegetative cell. By using differential interference microscopy, protargol impregnation, fluorescence labelling, scanning electron microscopy and transmission electron microscopy, microstructure and ultrastructure in C. australis was observed, like microtubular organelles, base microtubules, some features of microstructure in morphogenesis, cortical microtubules and cytopasmic organelles.1 Ciliate pattern and dorsal kineties morphogenesisC. australis was flexible and its cortical granules were yellow at low magnification. Through protargol impregnation, we knew that paroral membrane (PM) and endoral membrane (EM) crossed to form a circular area to be undulating membrane (UM), front-ventral-transverse cirri (FVTC) were distributed as the pattern of 8-5-5, left and right marginal cirri (LMC/RMC) were both one colume and separated from each other, three caudal cirri (CC),9-12 dorsal kineties (DK), macronucleus (Mac) had two with the shape of spheroidicity.On the dorsal surface about the division period of C. australis, there were three dorsal anlagens and four dorsomarginal anlagens while vegetative cell had twelve DK. However, according to the description of Cyrtohymena shii by Jasbir-Singh and C. australis, as one species same as C. shii in one genus named Cyrtohymena, twelve DK maybe developed like this:except four dorsomarginals anlagens gave rise to four DK for proter and opisthe, the first two of three dorsal anlagens gave rise to two bipolar DK while the third one gave rise to three, four, five, six, seven or even eight DK.2 Obseration by laser scanning confocal microscopyThe results about ciliature base microtubules in the cell cortex of C. australis are as follows. The membranelle brackets and its connected microtubules as well as the base-associated microtubules formed the microtubular cytoskeleton of the adoral zone membranelles (AZM). The base-associated microtubules of the undulating membranelles (UM), PM and EM crossed to form a circular area and contained microtubular cytoskeletal net. The base-associated microtubules of the FVTC and L/RMC generally contained anterior longitudinal microtubules (ALM), posterior longitudinal microtubules (PLM) and transverse microtubules (TM). Eight FC all had long PLM, and two FC had developed ALM; five VC all had developed PLM, and one which was near oral-end bracket had strong ALM; ALM of TC formed an area of cone and PLM scattered in the rear; LMC had ALM and PLM, but no obvious TM; RMC had ALM and developed TM. The results show the distribution pattern of base microtubules of C. australis has its species specificity, such as the components and different levels of the development of the L/RMC. Further, they illustrate morphology and construction of cortical microtubules had diversity.The results show that centrin were located in base and cilia rod of AZM、 UM、 FVTC and L/RMC by immunofluorescence. It supposed that centrin has a relationship with maintain and assembly of base and cilia rod.3 Obseration about ultrastructureThe results show the cilium pattern of C.australis had diversity by scanning electron microscope (SEM). The arrangement of FVTC was not strict accordance with the pattern of 8-5-5. The number of VC near the oral-end bracket and TC changed between three to nine and five to eight, and five VC are common. AZM of proter consisted of part reserve old AZM and new grown membrane in the degeneration area of old AZM, the feature is different from other ciliates. The cyst of C. australis belonged to "kinetosome-resorbing", internal of cyst were full of crossing fibers and granules, which may play important role in connection of fiber and were not observed in other cysts.Long fiber layer structure under the pellicle of C. australis may had function of support and firmness by transmission electron microscope (TEM). The base of membrance in AZM was separated by protuberance in adjacent pellicle, fibers both existed in protuberance and base of membrane and it answered the question of closely connection of membrane near to each other. Micronucleus (Mic) in cyst and vegetative cell were same, chromatin was full of Mic and nucleolus was not seen in Mic, but there were vesicles near the nuclear membranes continuous to cytoplasm and it supposed that Mic in cyst had some material exchange with cytoplasm. Mac in cyst had some obvious changes like most of nucleolus disappeared, some chromatin located in nuclear membranes, and numbers of mitochondria reduced. These features were relevant to their function. Cysts have many autophagic vacuoles and there were different matter in them like tightly wound fibers, glycogen granules, some lamellar structure and so on, but their role in cyst were not clear. The study about formation and function of autophagic vacuoles will have important significance for revealing the characteristics of cysts.