The Study On The Microtubular Organelles And Extrusive Organelles In Pseudourostyla Nova

The ciliates are the higher degree class of protozoan, and the cortical microtubular cytoskeletons of ciliates have some differentiation and specialization. The ciliature microtubular organelles are the important components of cortical microtubular cytoskeletons. The microtubules are the foundation which correlate to the ciliates activities closely, so it become the focus in the area of the protistology and cytobiology. To date, the related researches mainly focused on the cortical microtubular cytoskeletons of lower ciliates. However, the data are very limited about the extrusomes of the hypotrich ciliates. Study on the assembly mechanism of microtubular have important biological meaning for the further elucidation of heredity and regulation of ciliatures in ciliates.The cortical organelles in ciliates have some differentiation and specialization. Extrusomes are membrane-limited organelles and distributed widely in ciliated protozoa. Extrusomes play an important role in the life activity of ciliates. To date, the related researches mainly focused on the extrusomes of lower ciliates.On the contrary, the data are very limited about the extrusomes in hypotrich ciliates. The study on morphological characteristics, morphogenesis, and the location of extrusomes in hypotrich ciliates can supply the new data for further elucidation of the diversity and heredity of cell organelles, the relationship between function of organelles and cellular activity.The structure of ciliature microtubular organelles and extrusive organelles in Pseudourostyla nova were visualized using direct FLUTAX labeling, and the more delicate ultrastructure were observed by using scanning and transmission electron microscopy(SEM, TEM), and enzymo-cytochemistry. 1. The microtubular organelles and cytoplasm organelles in P. nova.1.1 The morphology and morphogenesis of microtubular organellesThe ciliature microtubular organelles in the ventral cortex of P. nova were visualized using direct FLUTAX. The organelles consist of adoral zone of membranelles (AZM), undulating membranes (UM), frontal-midventral-transverse cirri (FVTC), left and right marginal cirri (LMC and RMC) and the base-associated microtubules, etc. In the basal part of the AZM, there are membranelle brackets and the associated oral rib-wall microtubules. There are four types of microtubules at the base of FVTC:anterior longitudinal (ALM), posterior longitudinal (PLM), transverse (TM) and radiate microtubules (RM). These different types of microtubules differ from each other in developmental degree. During morphogenesis of the ciliature microtubular organelles, the disintegration of midventral cirri (MC) accompany with the generation of AZM primordia in opisthe and the regeneration of AZM primordia in proter; the disintegration of UM and MC accompany with the generation of UM and FVTC; the disintegration of LMC and RMC accompany with the generation of correspondence LMC and RMC. Among the generation of cirri primordia, part of basal bodies take part in formation of primordia, some old cirri (e.g. frontal, transverse and marginal cirri) could persist and remain unchanged for a long time and then they might absorbed by cell.As the result showing, The base-associated microtubules in the ventral cortex of P. nova possess some species-independent structural characters. During the process of the morphogenesis of the ciliatures, the old cirri play a role in positioning and material contribution. Moreover, in view of the cortex ciliature pattern of P. nova was not described correct yet, part of frontal cirri (FC) and MC which have similar morphology and location were separated in this article. The characteristics of base-associated microtubules among variation ciliatures have classificative value on separating the ciliatures which have similar morphology and location. The resule provide the foundation data for revealing the differentiation and diversity of cortical microtubular organelles in the hypotrich ciliates.1.2 The ultrustructure of microtubular and cytoplasm organelles in P.nova The cortical pellicle, cytoplasm beneath pellicle, cortical microtubular organelles and other organelles in hypotrich ciliates P. nova were observed by using transmission electron microscopy. Compared with Euplotes, the former has a tightly arranged microtubules layer beneath the pellicle, but the arrangement of microtubules in P. nova are random and discontinuous, it is speculated that have relationship with the morphology characteristic of Urostyla. Compared with higher development ciliates, such as Sporadotrichina and Euplotina, the FVTC, LMC and RMC are stronger, and the number of cirris is limited. But the FVTC, LMC and RMC are relatively smaller in P. nova. According to the significant difference among the different kinds of ciliates, this study further demonstrated that the development of cirri base-associated microtubules have relationship with the differentiation and specialization of cell. The aim of the present study is to futher elucidate the diversity of the ciliature microtubular organelles, and also provide the new data for classification in hypotrich ciliates.2. Study on extrusive organelles in hypotrichous ciliate P. nova2.1 The ultrastructure of extrusome in P. novaThe distribution, morphological characteristics, morphogenesis process, and extrusive process of the extrusive organelles in hypotrichous ciliate P. nova was observed by using scanning and transmission electron microscopy. The results show that the extrusomes in P. nova are different from the trichocysts in Paramecium. Extrusomes in P. nova are distributed irregularly throughout cytoplasm and the mature organelles are situated in cytoplasm beneath the pellicle; The anterior end of P. nova extrusomes possesses a cap-like structure consisted of multilayered membranes, It seems that during extrusion, cap and shaft of the extrusive organelles can be discharged outside the pellicle and the remaining non-discharged substance of the organelles is electron-lucent. The pellicular structure seems to be able to become intact again through membrane-fusion after extrusion. Vesicles irregular in size and shape, the vesicles are located densely in cytoplasm area around Golgi apparatus. They contain fibrous substance showing a low electron density similar to that of the remaining substance of the extrusionSo we can speculate that the extrusomes of P. nova might originate from the Golgi apparatus and become matured in cytoplasm.The observation that different fixative could cause various status of extrusomes suggests that these extrusomes play some defensive roles. The phenomenon that no extrusomes are distributed in cytoplasm regions surrounding AZM indicates that the extrusomes bear no relations with the predatory process of P. nova ciliate.2.2 The expression of acid phosphatase in extrusomeIn order to elucidate the destiny of remained substances after extrusion of the extrusomes, The ultrastructure of extrusomes of hypotrichous ciliate P. nova was observed by using transmission electron microscopy and enzymo-cytochemistry. In the extrusomes, acid phosphatase was found distributed only in the area with low electron density, so we speculate that the energy which generate through hydrolyzation of acid phosphatase maybe have relationship on the migration of mature extrusomes. A large quantity of acid phosphatase were demonstrated in the region with the residual structural substance of extruded extrusomes by enzymo-cytochemical electron microscopy in the present study. It could be speculated that the residual substance of extrusomes in P. nova might be reabsorbed and reused by ciliate cell via food vacuoles and take part in material recycling of the cell.