On The Cell Development Patterns In Some Important Groups Of Ciliated Protozoa

Ciliated protozoa is the most complex and highly differentiated among single-celled organisms,of which some groups are closely related to occurrence of red-tide, bait-animal culture in aquaculture, disease of animal, water quality purification in polysaprobic environment, material cycle and energy flow in"micro-food-loop". Moreover, owe to its special nuclear dualism, complicated morphogenetic process and unique sexual reproduction (conjugation), ciliates play important roles in molecular biology, cell biology and researches on relationship between nucleus and cytoplasm.(1) Main stages of general cortical development during binary division of Kiitricha marina which are characterized by"numerous"unique features that are never observed in all other known spirotrichs were investigated, the features are as follows: (1) no new UM-anlage in the opisthe is formed, hence the undulating membranes in the opisthe derive from the division of the de-differentiated parental ones; (2) no marginal cirral rows are formed; (3) no typical dorsal kineties (DK) are generated (i.e. several rows of pre-DK consisting of dikinetids with both basal bodies ciliated appear to mix with either isolated small cirri or cirral fragments; (4) all cirral anlagen are formed interkinetally from the de-differentiated old cirral rows; and (5) unlike all other known"hypotrichs"(s. l.), the differentiation of ciliature from the primordia occurs mostly after cell division. Based on all the morphogenetic information showing above, we conclude that Kiitricha may represent an intermediate taxon between heterotrichs (s. l.) and the Stichotrichia-Hypotrichia-complex and could be similar to the ancestor form of the latter group. So, Kiitricha might be placed in the class Spirotrichea at about subclass level, next to the Phaconidiidia, Hypotrichia, and Stichotrichia. We support the establishment of a new subclass Protohypotrichia Shi et al., 1999 within the class Spirotrichea and we transfer all taxa assigned to the order Kiitrichida to it.(2) The morphogenetic data reveals that the discocephalines have both stichotrich and hypotrich characteristics. Five morphogenetic characters are highly characteristic of the stichotrichs and only two morphogenetic features that are shared by discocephalines and euplotids to the exclusion of stichotrichs. On balance, therefore, the morphogenetic data suggest that the discocephalines are more closely related to the stichotrichs than the hypotrichs. Based on the data all above, we suggest that the discocephalines should have the taxonomic rank of order (i.e. Discocephalida Wicklow, 1982) as suggested by Puytorac et al. (1993), within the subclass Stichotrichia.(3) In general, the developmental pattern of Trachelostyla pediculiformis conforms to that of oxytrichids, i.e. typical 5-FVT-anlagen mode. It differs conspicuously in some other morphogenetic features from typical oxytrichids in some key points, e.g. the old AZM is renewed completely in the proter; the generation mode of dorsal kineties is of"one group type", and all three caudal cirri derive from the right-most 3 DK-anlagen (or kineties), and only two old dorsal kineties are involved in the construction of the new anlagen and the DK-anlage fragmentation occurs only in the single, left-most primordium. We conclude from the available morphogenetic evidence that: (1) Trachelostylidae, represented by the genus Trachelostyla, might be a lower but sister group to the closely-related family Oxytrichidae; (2) Gonostomum should be assigned to Oxytrichidae (s. l.).(4) The origin of marginal and dorsal kineties anlagen in Apokeronopsis crassa and Apokeronopsis ovalis, derived de novo, that means have no business with the old structure, and the developmental mode of the macronuclear nodules of this species (fuse into many masses) were shown for the first time, and Apokeronopsis nov. gen. was established based on morphogenetic data combined. Additionally we conclude that Apokeronopsis is a transitional form between the Pseudokeronopsinae and Thigmokeronopsis as it shares morphogenetic features with both.(5) The morphogenetic process of Diaxonella trimarginata almost follows a typical urostylid mode, one of the most significant morphogenetic features in D. trimarginata is the mode of the formation of the left marginal rows: only a single anlage develops intrakinetally to the right of the old left marginal rows, and then develops to replace the old structures, which is similar to that described in Pseudourostyla cristata and Pseudourostyla nov. The morphogenetic data suggest a close relationship between the genera Diaxonella and Pseudourostyla and we place the genus Diaxonella in the family Pseudourostylidae Jankowski, 1979.(6) Morphogenesis of Pseudoamphisiella alveolata was investigated and compared with its congener P. lacazei. With reference to the dissimilarities, we judged that morphogenetic patterns in the genus Pseudoamphisiella are not conservative. Moreover, on the same basis we suggest that the family Pseudoamphisiellidae might likewise be a highly evolved taxon within Urostylida and the assertion that pseudoamphisiellids at family level is justified.(7) The morphogenetic process of Metaurostylopsis sinica was thoroughly investigated. Compared with its congener M. marina, whose morphogenetic features was known, M. sinica shows some unique characteristics: the macronuclear nodules fuse into a single sausage-like mass; FVT-anlage streak n forms two frontoterminal cirri, an extra ventral cirrus and a transverse cirrus, i.e. typical urostylid mode but not a Metaurostylopsis mode. Metaurostylopsis was considered to be the sister group of the Pseudokeronopsidae because the macronucleus already shows the tendency not to fuse to a compact, globular mass and M. sinica is considered to be closer to the lower urostylids while M. marina is closer to the pseudokeronopsids. (8) The complete morphogenetic process of Chlamydodon mnemosyne (including the development of terminal and equtorial fragmnets) was reported and contributed new information to the understandability of morphogenesis of cyrtophorids.(9) As for morphogenesis, Hartmannula sinica correspond well with its congeners. This suggests that the mode of cell development among congeners could be very stable. The basic morphogenetic characteristics of H. sinica are in accordance with most other cyrtophorids (e.g. Hartmannulopsis, Thigmogaster, Chlamydonyx, Trochilioides, Brooklynella, Chilodonella and Trithigmostoma) in two main aspects: (1) the parental oral ciliature (circumoral and preoral kineties) is retained for the proter, and (2) the new oral primordium for the opisthe originates from several inner left somatic kineties.(10) Morphogenesis of Condylostoma spatiosum proceeds basically as described in a previous report and can be summarized as follows: (1) the parental adoral zone of membranelles is partly dedifferentiated and then renewed in the posterior portion; (2) in the proter, both the frontal cirri and the paroral membrane are newly formed by anlagen derived from the disaggregated old structures; (3) in the opisthe the anlagen of the paroral membrane and the frontal cirri develop from the right margin of the oral primordium; (4) two frontal cirri are formed one after the other by the frontal cirral anlage; (5) during morphogenesis, no recognizable duplication of basal bodies takes place in somatic kineties; and (6) macronucleus divides after prior fusion.(11) The morphogenetic process of Oxytricha, Euplotes charon and Diophrys apoligothrix thoroughly described and compared with their congeners. The result shows that the morphogenesis of these 4 genera is highly conservative.(12) A new genus Apokeronopsis nov. gen. was established and other two Thigmokeronopsis Wicklow, 1981 and Diaxonella Jankowski, 1979 are redefined.(13) Two new combinations, Apokeronopsis crassa (Claparède & Lachmann, 1858) Shao et al. 2008 and Apokeronopsis antarctica (Petz, 1995) Shao et al. 2008 are proposed. Two new species, Hartmannula sinica and Metaurostylopsis sinica, are also suggested.