Transmission Electron Microscopical Observations on Stomatogenesis during Metamorphosis of Eufolliculina uhligi (Ciliophora: Heterotrichida)1

Stomatogenesis during metamorphosis of the marine loricate ciliate, Eufolliculina uhligi, was observed by transmission electron microscopy. Kinetosome proliferation in the stomatogenic territory leads to the formation of an anarchic field. This separates into the left adoral and the right paroral primordia. Both primordia consist of pairs of kinetosomes. One kinetosome of a pair is associated with one transverse and two postciliary microtubules; the other has one transverse microtubule. The postciliary microtubules of the adoral kinetosomes become divergent; those of the paroral kinetosomes become convergent. The adoral kinetosomes arrange in promembranelles. Then a third row of kinetosomes is produced anteriorly to each promembranelle. This third row is short at the peristome but longer in the buccal area. The paroral kinetosomes form a stichodyad. The buccal part of the paroral primordium is resorbed during formation of the buccal cavity. Stomatogenesis ends with the development of a functioning cytostome. During this process, the postciliary microtubules of the buccal adoral membranelles elongate and become associated with cytopharyngeal vesicles. Fusion of these vesicles with the cytostome has been observed some time after the completion of the oral structures.     

The Cortical Morphogenetic Cycle Associated with Cell Division in Diophrys Dujardin, 1841 (Ciliophora,Hypotrichida)1

Morphogenesis of cell division was investigated in Diophrys scutum, D. oligothrix, and D. appendiculata utilizing both light microscopy of living and stained specimens and SEM of preserved specimens. The cortical morphogenetic pattern of Diophrys is similar to that of other members of the family Euplotidae. The opisthe oral primordium, which develops in a subsurface pouch, forms posterior to the parental buccal cavity. The proter inherits the parental adoral zone of membranelles (AZM) apparently unchanged. The endoral membrane forms to the right of the posterior end of the AZM in the proter, in association with the developing AZM in the opisthe. The paroral cirrus and membrane develop from a single streak that first appears along the right edge of the buccal cavity in the proter to the right of the developing buccal structures of the opisthe. Frontal and transverse cirri develop in both proter and opisthe from five separate cirral primordia that form to the right of the buccal cavity. Left marginal cirri do not develop in association with the corresponding parental structures. Kinetosomes formed within the opisthe oral primordium, or kinetosomes that were part of any parental ciliary structure, do not appear to become part of any developing paroral structures, frontal, transverse, or left marginal cirri. Speciation within the genus Diophrys and evolution of the family Euplotidae as they relate to the morphogenesis of cortical structure are discussed.     

Morphological description of three marine ciliates (Ciliophora, Scuticociliatia), with establishment of a new genus and two new species

Three marine scuticociliates, Falcicyclidium fangi nov. gen., nov. spec., Falcicyclidium atractodes nov. spec., and Cristigera media Kahl, 1928 were investigated using live observation and silver impregnation methods. The genus Falcicyclidium is distinguished by the combination of: (i) dorsoventrally flattened body, (ii) hook-like (falciform) paroral membrane, (iii) anterior end of paroral membrane posterior to anterior end of membranelle 1, and (iv) multiple caudal cilia. Falcicyclidium fangi nov. spec., the type of the new genus, can be recognized by the combination of its large size, extremely dorsoventrally flattened (3:1) body, consistently 10 somatic kineties, and the broad, elongate buccal area occupying 60% of the body length. Falcicyclidium atractodes nov. spec. is mainly characterized by a unique spine projecting from both the anterior and posterior end. The uncommon form, Cristigera media is redescribed based on the population from Qingdao, the statistic data and additional features, especially the morphology of the living cells, are documented.     

Morphogenesis in the Heterotrich Ciliate Climacostomum virens. II. Oral Development During Regeneration1

The regeneration (RG) of the oral apparatus (OA) by Climacostomum virens (Ciliophora, Heterotrichida) is examined by estimation of the ability of live cells to ingest food as well as by Nomarski interference contrast microscopy, bright field microscopy of protargol-stained specimens, and by scanning electron microscopy. When placed in a 6% (w/v) urea solution for ～ 2 min 10 sec, populations of 10,000–100,000 cells shed a large part of their OA. In more than 90% of the cells that shed, the discarded segment is comprised of the apical membranelles, most of the adoral membranelles, and of a variable part of the buccal tube. After washing and incubation at 26°C, 50% of the cells regenerate a functional OA in 4 h 47 min, and after 5 h 26 min, 90% of the cells are able to ingest food. At any given moment during the process, 50–90% of the cells are morphologically in the same stage of RG. Seven stages (among which three are divided into two substages) of RG are defined. The process begins by the disorganization of the remnant oral structures. Concomitantly, kinetosomes multiply along the kineties of the zone of discontinuity and form the longitudinally oriented oral primordium. The latter gives rise to the adoral primordium, which rapidly produces the adoral zone of membranelles (AZM), and to the paroral primordium, which subsequently forms the apical membranelles, the buccal peristomial kineties, and the paroral kinety. Morphogenetic movements lead to incurvation of the AZM and the frontal field and to invagination of the buccal tube.     

Dexiotrichides pangi n. sp. (protozoa,ciliophora, scuticociliatia), a new marine ciliate from the north China sea

The morphology, infraciliature, and silverline system of a new marine scuticociliate, Dexiotrichides pangi n. sp. were investigated. The new species is characterized by: size about 45-65 x 20-25 microm in vivo with kidney-like body shape and obliquely truncated semicircle-shaped apical plate; cytostome at bottom of conspicuously depressed oral cavity, which is located at the cell equatorial level; paroral membrane extending anteriorly to membranelle 3; scutica multi-rowed; 33-38 somatic kineties; contractile vacuole near ventral side and subcaudally positioned, opening at posterior end of somatic kinety 3; one oval macronucleus and one small micronucleus; caudal cilium positioned in a small pouch; marine habitat. Based on the data obtained, an improved diagnosis for the genus Dexiotrichides is suggested: body with circular cross-section and conspicuous cilia-free apical plate; buccal cavity conspicuously depressed with cytostome located near or at equatorial level; three membranelles transversely orientated each with 2-3 rows; paroral membrane zigzaging structure, extending to about half of the length of buccal field; multi-rowed scutica; somatic kinety one strongly shortened and terminating anteriorly at posterior end of buccal field; basal bodies in equatorial region arranged usually in circular pattern, while in the anterior portion of somatic kinety 2, basal bodies characteristically in pairs and separated from the posterior part of kinety 2; one caudal cilium.     

Morphogenesis in the Heterotrich Ciliate Climacostomum virens. I. Oral Development During Cell Division

The principal characteristics of stomatogenesis during division in Climacostomum virens are: (A) Kinetosomal proliferation on the left side of a variable number of kineties in the ventral somatic cortex forms an oral primordium consisting of several kinetosomal fields, which then fuse to form a single anarchic field. (B) A constant topographical relationship exists between the primordium and a well defined cortical pattern, the zone of discontinuity. (C) The anarchic field primordium divides into 2 unequal parts—to the left, the AZM primordium, and to the right, the paroral primordium, which differentiates into the apical membranelles, the peristomial field, and the buccal tube. (D) Preoral and oblique kineties of the somatic cortex form along the right side of the paroral primordium. (E) Parental oral structures are partially dedifferentiated. Stomatogenesis in C. virens and other heterotrichs is compared.     

Stomatogenesis during sexual and asexual reproduction in an amicronucleate strain of Paramecium caudatum.

Amicronucleate cells of Paramecium caudatum, whose micronuclei have been artifically removed by micropipetting, are characterized by the appearance of a deciliated area at the posterior part of the buccal opening. These cells form food vacuoles at a slightly lower rate than micronucleate cells. Their mean interfission time is longer than that in micronucleates. The exconjugants of amicronucleate cells can not form food vacuoles and eventually die witout fission, though conjugation proceeds normally in them as well as in their micronucleate mate. The oral apparatus of amicronucleate exconjugants seems to be shallower than that of micronucleates. The membranellar cilia, therefore, can be seen through the buccal overture by scanning electron microscope. The results obtained from the cross of micronucleate and amicronucleate strains and from the induction of autogamy in amicronucleate strains suggest that the micronucleus has a primary role in developing the normal oral apparatus after nuclear reorganization.     

Ultrastructural aspects of the somatic and buccal infraciliature ofColeps amphacanthus Ehrenberg 1833

Summary Somatic and buccal infraciliature ofColeps amphacanthus Ehrenberg 1833 were studied by light and electron microscopy. The somatic kineties are composed of monokinetids and 2 dikinetids at the anterior end of each kinety. The monokinetids are associated with postciliary microtubules at triplet 9, a kinetodesmal fiber at triplet 5 and 7 and nearly radially arranged transverse microtubules at triplet 4. The associated fibrillar systems of the posterior kinetosome of the dikinetids are like those of the monokinetids. The anterior kinetosome is associated with transverse microtubules at triplet 4 and one or few postciliary microtubules at triplet 9. The anterior kinetosome bears only a short cilium.The oral ciliature is composed of a kinety of nearly circumorally arranged paroral dikinetids and 3 adoral organelles at the ventral left side of the oral opening. Nematodesmata arising from the oral ciliature form the major component of the cytopharyngeal apparatus which is lined by microtubular ribbons of postciliary origin. The buccal cavity is surrounded by oral papillae which often contain toxicysts.     

Microtubular Systems of Paramecium in Division: Pattern of Cytospindle Assembly

The pattern of cytospindle assembly and the modifications of the microtubular cytoplasmic network during division of Paramecium are studied by means of indirect immunofluorescence. The assembly of cytospindle starts at two independent areas placed respectively around the proter's and opisthe's buccal overture. The moment of the microtubule bundles’appearance depends on their distance from the buccal opening, with those closest appearing 1st. The existence of microtubule organizing centers that act transiently during division of Paramecium is discussed.     

Chloroplast actin filaments organize meshwork on the photorelocated chloroplasts in the moss <Emphasis Type="Italic">Physcomitrella patens</Emphasis>

Cytoskeleton dynamics during phototropin-dependent chloroplast photorelocation movement was analyzed in protonemal cells of actin- and microtubule-visualized lines of Physcomitrella patens expressing GFP- or tdTomato-talin and GFP-tubulin. Using newly developed epi- and trans-microbeam irradiation systems that permit fluorescence observation of the cell under blue microbeam irradiation inducing chloroplast relocation, it was revealed that meshwork of actin filaments formed at the chloroplast-accumulating area both in the avoidance and accumulation movements. The structure disappeared soon when blue microbeam was turned off, and it was not induced under red microbeam irradiation that did not evoke chloroplast relocation movement. In contrast, no apparent change in microtubule organization was detected during the movements. The actin meshwork was composed of short actin filaments distinct from the cytoplasmic long actin cables and was present between the chloroplasts and plasma membrane. The short actin filaments emerged from around the chloroplast periphery towards the center of chloroplast. Showing highly dynamic behavior, the chloroplast actin filaments (cp-actin filaments) were rapidly organized into meshwork on the chloroplast surface facing plasma membrane. The actin filament configuration on a chloroplast led to the formation of actin meshwork area in the cell as the chloroplasts arrived at and occupied the area. After establishment of the meshwork, cp-actin filaments were still highly dynamic, showing appearance, disappearance, severing and bundling of filaments. These results indicate that the cp-actin filaments have significant roles in the chloroplast movement and positioning in the cell.     

Ultrastructure and Cortical Morphogenesis in the Euplotine Hypotrich Certesia quadrinucleata Fabre-Domergue, 1885 (Ciliophora,Protozoa)1

The cortical development during cell division and the interphase ultrastructure of the marine interstitial hypotrich Certesia quadrinucleata is described using light microscopy and both scanning and transmission electron microscopy. Membranelles are paramembranelles; postciliary microtubules from rightmost membranellar kinetosomes line the buccal cavity and separate parallel arrays of pharyngeal discs that border the cytopharynx. A large paroral membrane is present; an endoral membrane is absent. Alveolar plates lie within alveolar membranes except in regions where organelles and organellar complexes (cirri, the condylopallium, dorsal bristles, membranelles, and the paroral membrane) emerge from the cortex. Muciferous-like bodies attach to the plasma membrane in these regions. Dorsal bristles possess transverse and postciliary microtubules as well as kinetodesmal fiber like those of other hypotrichs. Lasiosomes are present. A unique bulbous structure—the condylopallium—protrudes from the anterior right of the cell. The morphogenetic pattern is euplotine in that cortical development begins in one latitudinal zone, and the oral primordium of the opisthe develops within a subsurface pouch apart from the frontal primordia. Microtubular bundles appear beside (later attached to) developing frontal anlagen; they disappear after cirri are in final interphase locations. Although possessing unique characters, Certesia shares a close phylogenetic relationship with Euplotes.     

尖前口虫的口器发生研究(纤毛门, 膜口目)

研究了咽膜类纤毛虫尖前口虫无性生殖期的核器及口器的演化.其发生特征为;1)新的口原基形成于原前庭动基列与口侧膜间,表观为原口侧膜分裂而致;2)随着形态发生的进行,由口原基依次演化出后仔虫的三片咽膜、口侧膜和三条前庭动基列;3)原口器完全被前仔虫所继承;4)体纤毛器在整个形态发生过程中一直保持双动基列结构.       

Phytochrome-induced intercellular signalling activates cab::luciferase gene expression

The phytochrome-induced expression pattern of the chlorophyll a/b binding protein (cab) gene was studied using a cab2::luciferase reporter transgene in the tobacco cotyledon. The role of developmentally regulated competence, cooperativity among cells and signal propagation was investigated by red-light microbeam irradiation of distinct areas of the cotyledon. Even with a minimal fluence, the response was not restricted to the irradiated cells. Following irradiation of the cotyledon base, the luciferase activity revealed a robust propagation of activating signals to areas that had not received a light stimulus. The acropetal outspread formed distinct expression patterns depending on the site of the irradiation. The combination of imaging luciferase activity in living seedlings and microbeam microscopy provides significant experimental evidence of how cellular light perception and intercellular signalling contribute to the cab gene expression pattern.     

Ontogeny and molecular phylogeny of a new marine ciliate genus,Heterokeronopsis g. n. (Protozoa,Ciliophora, Hypotricha), with description of a new species

The morphology and morphogenesis of a new ciliate, Heterokeronopsis pulchra g. n., sp. n., isolated from a mangrove wetland near Shenzhen, southern China, were investigated using live observation and protargol impregnation methods. Heterokeronopsis g. n. is characterized by having a bipartite adoral zone, an extremely shortened paroral membrane, frontal cirri arranged in an indistinct bicorona, a midventral complex composed of midventral pairs and midventral row(s), one left and one right marginal row, bipolar dorsal kineties, and buccal cirri; frontoterminal, transverse, and caudal cirri are absent. The single species H. pulchra sp. n. has a long, slender body that is brownish in colour, two kinds of cortical granules, one posteriorly located contractile vacuole, one buccal cirrus, usually six frontal cirri, three dorsal kineties, and one midventral row. The main morphogenetic features are: (i) the old oral apparatus is completely replaced by new structures derived from the oral primordium of the proter which originates de novo on the dorsal wall of the buccal cavity, (ii) the posteriormost frontal-midventral-transverse cirral anlage generates a midventral row, (iii) no frontoterminal and transverse cirri are formed, (iv) the anlagen for the marginal rows and the dorsal kineties are formed intrakinetally, and (v) the macronuclear nodules fuse into a mass at the middle stage. Phylogenetic analyses based on SSU rRNA gene sequence data reveal that Heterokeronopsis pulchra is a member of the family Pseudokeronopsidae and is most closely related to Nothoholosticha fasciola.     

Corticocolpoda kaneshiroae N. G., N. Sp., a New Colpodid Ciliate (Protozoa, Ciliophora) from the Bark of Ohia Trees in Hawaii

Corticocolpoda kaneshiroae n. g., n. sp. was discovered in the bark of Ohia trees (Metrosideros polymorpha) from the Hawaiian Archipelago. Its morphology and infraciliature were studied in live cells, with the scanning electron microscope, as well as in specimens impregnated with protargol, silver nitrate, and silver carbonate. The new genus, Corticocolpoda, belongs to the family Colpodidae and is unique in having a left oral ciliary field (polykinetid) composed of 13–20 equidistantly spaced, paired rows of monokinetids. The new species, C. kaneshiroae, measures 100–300 × 60–250 μm and has a huge vestibulum used to capture large food items, mainly other ciliates. The oral ciliary fields are within the vestibulum and of equal length; the right field is a paroral membrane composed of a single row of dikinetids. Several micronuclei are attached to the ellipsoid macronucleus. The mucocysts are inconspicuous and arranged around the somatic dikinetids. The resting cyst is globular and has a 1–2 μm thin, firm, yellowish inner wall and a 20-μm-thick, fragile, hyaline outer wall. Convergent evolutionary paths and a possible polyphyly of the Colpodidae are discussed. An improved key to the genera of the family Colpodidae is provided. Twenty-three species of ciliates and one flagel***iate (Hemimastix amphikineta), which occurred together with C. kaneshiroae, are new for the fauna of Hawaii and listed in the ecology section.     

Cortical Ultrastructure of the Scuticociliates Dexiotricha media and Dexiotricha colpidiopsis (Hymenostomata)*†

SYNOPSIS. Cortical ultrastructure of the scuticociliates Dexiotricha media and Dexiotricha colpidiopsis was investigated. The following elements of the somatic cortex were studied: the cell membrane, alveolar membranes and the epiplasm, kinetodesmal fibers, postciliary and transverse microtubular ribbons, and transverse fibers associated with single and paired kinetosomes; mitochondria and single microtubules located in interkinetal ridges; mature and early extrusion stages of mucocysts: the expulsion vacuole pore and tube, the nephridioplasm and the cytoproct. In the buccal cortex, the paroral kinety-ribbed wall complex, the 3 polykineties, and the cytostome-cytopharynx were investigated. Comparative survey of ciliate ultrastructure indicates 2 principal orientation patterns for kinetodesmal and postciliary fibers, recognition of which leads to reevaluation of the theory of paroral kinety formation and the ideas of homology based on this theory. Ultrastructurally, the scuticociliates are not distinct from tetrahymenines and peniculines; the 3 groups appear to be 1 assemblage.     

Differentiation of the inner ear sensory epithelia of Proteus anguinus (Urodela,amphibia)

The stages of differentiation of the inner ear sensory epithelia of the neotenous cave urodele, Proteus anguinus, was studied with light and electron microscopy. Comparative ultrastructural analysis among specimens of different sizes confirms that new sensory cells may be generated throughout life, particularly along the periphery of the saccular macula. The inner ear of Proteus contains at least four types of sensory cells that differ in their apical ciliary part. The lungs and air-filled buccal cavity may function as transducers of sound pressure in underwater conditions. Sound waves might be transmitted from the buccal cavity to the connected oval window. The very complex orientation of the sensory hair cells of the saccular macula and the large overlying saccular otoconial mass suggest that this macula facilitates orientation of Proteus in its underground aqueous habitat.     

Ultrastructure and cell size-dependent regulation of the adoral zone of membranelles in the heterotrich ciliate Stentor coeruleus

The number and length of oral membranelles were determined for both large and small Stentor from well-fed, growing cultures and nutrient-deprived cultures, respectively. Small cells possess both significantly fewer and shorter membranelles than do large cells. For both large and small cells, each membranelle is composed of three rows of basal bodies. The membranelles closest to the gullet have a third row that is only slightly shorter than the other two. The third row becomes rapidly shorter as membranelles become increasingly distant from the gullet. A short distance from the gullet, and for the remainder of the band, the third row is composed ofonly one to four basal bodies. The first two rows consist of approximately 35 basal bodies each in large cells and approximately 26 basal bodies each in small cells. This indicates that Stentor regulates the number of basal bodies per row, but not the number of rows, in response to changes in cell size. © 1992 Wiley-Liss, Inc.     

Chloroplasts do not have a polarity for light-induced accumulation movement

Chloroplast photorelocation movement in green plants is generally mediated by blue light. However, in cryptogam plants, including ferns, mosses, and algae, both red light and blue light are effective. Although the photoreceptors required for this phenomenon have been identified, the mechanisms underlying this movement response are not yet known. In order to analyze this response in more detail, chloroplast movement was induced in dark-adapted Adiantum capillus-veneris gametophyte cells by partial cell irradiation with a microbeam of red and/or blue light. In each case, chloroplasts were found to move toward the microbeam-irradiated area. A second microbeam was also applied to the cell at a separate location before the chloroplasts had reached the destination of the first microbeam. Under these conditions, chloroplasts were found to change their direction of movement without turning and move toward the second microbeam-irradiated area after a lag time of a few minutes. These findings indicate that chloroplasts can move in any direction and do not exhibit a polarity for chloroplast accumulation movement. This phenomenon was analyzed in detail in Adiantum and subsequently confirmed in Arabidopsis thaliana palisade cells. Interestingly, the lag time for direction change toward the second microbeam in Adiantum was longer in the red light than in the blue light. However, the reason for this discrepancy is not yet understood. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.