Euplotes raikovi Agamaliev, 1966 (Ciliophora, Hypotrichida) From New Hampshire: Description and Morphogenesis

Euplotes raikovi, an interstitial hypotrich ciliate described once from the Caspian Sea, was isolated from intertidal sand at Rye Harbor, New Hampshire. Specimens were observed in life, and also stained by Corliss’ modification of the Chatton-Lwoff wet-silver technic and by 2 nigrosin methods. Living individuals and those fixed with Parducz's fluid are 43 × 30 (37-50 × 25–35) μm. The AZM has an average length of 27 μm and contains 24–32 membranelles. The anterior part of AZM lies on the ventral face of an apical channel, much as in E. bisulcatus. There are 7 fronto-ventral, 4 transverse, 1 left marginal, and 2 right caudal cirri. An additional small, rounded argentophilic area resembling a cirrus base is evident in silver-stained preparations, but it is barren in virtually 100% of the population. There are 7–8 (usually 7) dorsal ciliary rows with E. patella-type argyrome. The modal number of cilia in rows I-VII are 3-7-9-9-9-10-10. The unique fronto-ventral cirrus pattern is stable and predictable at the time of streak phase. Morphogenetic development indicates that the barren cirrus base is 2/V (Wallengren system), and that it apparently buds from 1/V. The left marginal cirrus and right caudal cirri have different origins.     

Species Structure in Euplotes crassus (Ciliophora, Hypotrichida)

ABSTRACT. We observed different low salinity tolerances between two groups of populations of Euplotes crassus. After mating analysis, the less tolerant populations could be assigned to three mating groups. Two of them were separated by preconjugative barriers but both conjugated with a third one. A breeding test showed evidence of (potential) introgression mediated by this "bridging" group. On the other hand, the more tolerant populations formed a fourth mating group unable to conjugate with the others and characterized by distinct zymogram patterns. We conclude that natural introgression among the studied populations is not complete and that the species structure of E. crassus comprises intrafertile sets of populations among which gene flow may be difficult or virtually absent.     

Time-course analysis of nuclear events during conjugation in the marine ciliate Euplotes vannus and comparison with other ciliates (Protozoa,Ciliophora)

Ciliates represent a morphologically and genetically distinct group of single-celled eukaryotes that segregate germline and somatic functions into two types of nuclei and exhibit complex cytogenetic events during the sexual process of conjugation, which is under the control of the so-called “mating type systems”. Studying conjugation in ciliates may provide insight into our understanding of the origins and evolution of sex and fertilization. In the present work, we studied in detail the sexual process of conjugation using the model species Euplotes vannus, and compared these nuclear events with those occurring in other ciliates. Our results indicate that in E. vannus: 1) conjugation requires about 75 hours to complete: the longest step is the development of the new macronucleus (ca. 64h), followed by the nuclear division of meiosis I (5h); the mitotic divisions usually take only 2h; 2) there are three prezygotic divisions (mitosis and meiosis I and II), and two of the eight resulting nuclei become pronuclei; 3) after the exchange and fusion of the pronuclei, two postzygotic divisions occur; two of the four products differentiate into the new micronucleus and macronucleus, respectively, and the parental macronucleus degenerates completely; 4) comparison of the nuclear events during conjugation in different ciliates reveals that there are generally three prezygotic divisions while the number of postzygotic divisions is highly variable. These results can serve as reference to investigate the mating type system operating in this species and to analyze genes involved in the different steps of the sexual process.     

卡龙游仆虫无性生殖期间的形态发生学研究：原生动物,纤毛虫

卡龙游仆虫为海洋中自由生纤毛虫,利用银染法对该种二分裂期间的形态发生学进行了初步的研究,其主要过程为：１．伴随大核改组带的出现和ＤＮＡ复制开始,口原基发生于老口围 方皮膜下一龛腔内,后由前至后组装成围口小膜而演化为后ＡＺＭ。老口围带及口侧膜在原位被被前仔虫继承;２．体棘毛场首先出现两组棘毛原基,其随后各自独立演化成９根前、后仔虫的额－腹－横棘毛;３．缘棘毛原基也为独立发生,初为单一,后断裂为二并分     

用非离子去垢剂抽提获得的小游仆虫皮层细胞骨架的构形

由扫描电镜术显示,应用非离子去垢剂抽提获得的小游仆虫(Euplotes grocilis)皮层细胞骨架是由非纤毛区皮层骨架、纤毛器骨架及其附属纤维等构成的三维结构网架。各类细胞骨架以纤维物质为基本成分组成纤维网、纤维层、纤维束和纤维薄片等不同形态单元。其中：非纤毛区皮层骨架以表面纤维网和表膜下纤维层为形态单元位于细胞的外周层;纤毛器骨架中的口围带骨架、口侧膜骨架、额腹横棘毛骨架按各自的分布图式在皮层内定位,成为主要的皮层骨架结构。尽管这些纤毛器骨架显示不同的形态,但却具有相同的建构特征,即都是由纤毛器的毛基体、纤毛器托架和骨架附属纤维相互联系镶嵌在一起形成的相对独立的结构单元。分析推测,游仆虫皮层表面纤维网使细胞表面形成区域化结构,它也可能与细胞表面各部分的联系及其细胞与环境的相互作用有关;纤毛器骨架中各个纤毛器的毛基体复合结构可能对纤毛器托架和骨架附属纤维等起到微管组织中心的作用。     

镰游仆虫腹面皮层细胞骨架的扫描电镜观察

应用非离子去垢剂抽提和扫描电镜样品制备、观察相结合的方法，显示了镰游仆虫的腹面皮层细胞骨架，详细描述了处于毛基体和毛基体下水平的口围带、口侧膜、额腹横棘毛骨架，以及口围带小膜托架、口侧膜托架、额腹横棘毛托架的主要附属纤维和非纤毛区表膜下皮层骨架的立体图形。作者据所述各种纤毛器托架附属纤维的定位和分布特征推测，这些附属结构可能与细胞内各种纤毛器间的联系，以及包括纤毛器运动在内的整个细胞运动的协调等有关。     

“Candidatus Euplotechlamydia quinta,” a novel chlamydia-like bacterium hosted by the ciliate Euplotes octocarinatus (Ciliophora,Spirotrichea)

Our knowledge of ciliate endosymbiont diversity greatly expanded over the past decades due to the development of characterization methods for uncultivable bacteria. Chlamydia-like bacteria have been described as symbionts of free-living amoebae and other phylogenetically diverse eukaryotic hosts. In the present work, a systematic survey of the bacterial diversity associated with the ciliate Euplotes octocarinatus strain Zam5b-1 was performed, using metagenomic screening as well as classical full-cycle rRNA approach, and a novel chlamydial symbiont was characterized. The metagenomic screening revealed 16S rRNA gene sequences from Polynucleobacter necessarius, three previously reported accessory symbionts, and a novel chlamydia-like bacterium. Following the full-cycle rRNA approach, we obtained the full-length 16S rRNA gene sequence of this chlamydia-like bacterium and developed probes for diagnostic fluorescence in situ hybridizations. The phylogenetic analysis of the 16S rRNA gene sequences unambiguously places the new bacterium in the family Rhabdochlamydiaceae. This is the first report of chlamydia-like bacterium being found in Euplotes. Based on the obtained data, the bacterium is proposed as a new candidate genus and species: “Candidatus Euplotechlamydia quinta.”     

Methods for Inducing Selfing, Selfing and Its Role in the Life Cycle of Euplotes woodruffi syngen 3 (Ciliophora)

Methods for inducing selfing, and the relation between selfing and the life cycle of Euplotes woodruffi syngen 3 are reported. Three intercrossing stocks were used in this experiment. Selfing was induced with several treatments as follows: cell-free fluid from the cultures of complementary mating types; intact cells of GI or S phase in the cell cycle; heat-killed cells, and lysed cells of GI-, S-, and D-phase cells which were prepared by freeze-thawing. Stock SJ-27 was used as a parental stock from which Fl clones were originated through selfing. The other two stocks, SJ-8 and SJ-19, were used as testers. The period of immaturity varied from clone to clone. The heterotypic conjugation of clones with cells of stock SJ-8 seems to occur earlier in the life cycle than with cells of stock SJ-19. This result shows that this syngen has an adolescent period in the life cycle. The length of selfing immaturity seems to be different from that of crossing immaturity, and selfing appeared slightly later than crossing with testers. But the clones in which selfing 1st occurred are considered to be in adolescence or maturity, not in senility. Once selfing appeared in any clone, the clone continued to produce selfing pairs till just before clonal death. The viability of selfing and of outcrossing were compared and found not significantly different. Inbreeding depression took place in some of the F2 clones by successive selfing. The viability of F2 clones from young parents was significantly higher than that from old parents (220 to 230 fissions) both in selfing and outcrossing. The total life spans which were studied in three F1 clones were 168 to 264 fissions.     

Local and Temporal Pattern of Con A-Binding Site Aggregation During Conjugation in Euplotes vannus (Ciliophora,Hypotrichida)1

ABSTRACT. Conjugating cells of Euplotes vannus (syngens Naples and Barcarès) were investigated for Con A-binding sites by means of fluorescence microscopy. Cells fixed with 0.4% paraformaldehyde and incubated with 15 μg/ml FITC-Con A showed a distinct region of strong fluorescence, the size, shape and localization of which characteristically changed during the course of conjugation, first appearing at courtship stage (cells contact without forming pairs) and vanishing soon after the migration pronuclei have been exchanged, but before cells have separated. Con A binding and conjugation were blocked by cyclohexamide and α-galactosidase. Con A-binding was also inhibited by α-mannosidase, α-glucosidase and β-galactosidase without affecting conjugation except a delay of pair formation. The results suggest an involvement of newly formed or translocated glycoconjugates in cell pairing during conjugation.     

Cytochemical investigations of the alveolar plates of theEuplotidae (Ciliophora,Hypotrichida)

Summary The ultrastructural appearance of organic plates lying in the alveoli of a freshwater species ofEuplotes is described and seen to be similar to those previously reported from the marine speciesE. vannus. Enzymatic digestion using pepsin and trypsin indicates that the plates in both species are mainly composed of protein with a fine coating of polysaccharides, as revealed using the Thiéry-technique for polysaccharide staining.     

拟翁口虫形态学及形态发生学现象的初步研究

应用荧光紫杉醇直接荧光标记方法显示了一种腹毛类纤毛虫拟翁口虫(Onychodromopsis sp.)腹皮层纤毛器微管胞器及形态发生,根据该纤毛虫的皮层纤毛模式和纤毛器基部微管的形态,将其归为侧毛虫科(Pleurotrichidae)拟翁口虫属(Onychodromopsis);并据后仔虫口原基的发生、左右缘棘毛原基的...     

Redescription of Phacodinium metchnikoffi (Ciliophora, Hypotrichida): General Morphology and Taxonomic Position

ABSTRACT Living and stained specimens of Phacodinium metchnikoffi , collected near Madrid, Spain, were studied under light microscopy. Infraciliature was stained using a silver-impregnation procedure. The somatic infraciliature is composed of a relatively small number of discontinuous kineties, formed by groups of few kinetosomes (pallets). The buccal ciliature is composed of an adoral zone of membranelles and a paroral formation otherwise unknown in ciliates, with many short kineties, which lie on a rigid stem. We propose that P. metchnikoffi is a primitive hypotrich and, consequently, we present a new classification system for hypotrichs.     

The Order Euplotida (Ciliophora): Taxonomy, with Division of Euplotes into Several Genera

ABSTRACT. The order Euplotida represents a monophyletic order of five families of hypotrich ciliates united by morphology, stomatogenesis, ultrastructure, cyst structure, and behavior. A review of variability of ciliation and nuclei among the 14 genera suggests that lines of evolution may have involved both the loss of cirri and nuclear simplification. We present a binary key to genera in the families Aspidiscidae ( Aspidisca and Euplotaspis ), Certesiidae n. fam. ( Certesia ), Gastrocirrhidae ( Cytharoides, Euplotidium , and Gas-trocirrhus ), Uronychiidae ( Diophryopsis, Diophrys, Paradiophrys , and Uronychia ), and Euplotidae. The latter family contains species formerly in the genus Euplotes. Based primarily on cortical structure, endosymbionts, data from morphometric analysis, and ecology, we recognize four different groups. The first group of species remains in Euplotes with Euplotes charon as type. We place a second group of species into the genus Moneuplotes Jankowski 1979 with Moneuplotes vannus (Müller, 1786) as type. We erect two new genera: Euplotoides n. g. and Euplotopsis n. g. with Euplotoides patella (Müller, 1773) n. comb. and Euplotopsis affinis (Dujardin, 1841) n. comb. as type species respectively. We discuss possible phylogenetic relationships within the order.     

Redefinition of the Urostylidae (Ciliophora,Hypotrichida) on the Basis of Morphogenetic Characters*

SYNOPSIS Examination of stained specimens (protargol and nigrosinbutanol) of hypotrich ciliates during division allows understanding of morphogenesis of buccal structures and cirri. Midventral, frontal, and transverse cirri in both proter and opisthe of Urostyla marina differentiate from a longitudinal series of numerous oblique ciliary streaks in a manner similar to that of Bakuella, Holosticha, Keronopsii. Pseudourostyla, and Uroleptus. This pattern differs markedly from that in Amphisiella, Kahliella, Paraholosticha, and Paraurostyla, in which the fronto-ventral and transverse cirri arise from a series of fewer (2–5) ciliary streaks in a longitudinal or fan-like array. Rows of marginal cirri in U. marina arise independently, as in Urostyla grandis. On the basis of comparisons of both structural and morphogenetic features of this and other hypotrichs, the family Urostylidae is redefined to contain Urostyla (type), Bakuella, Holosticha, Keronopsis, Pseudourostyla, and Uroleptus. Other genera formerly contained in the families Holostichidae and Urostylidae are placed in synonymy, assigned to other families, or held in uncertain familial relationship pending their rediscovery and further investigation.     

A Comparative Analysis of the Morphology and Morphogenesis of Gonostomum strenua (Engelmann, 1862) (Ciliophora, Hypotrichida) and Related Species

The morphology and morphogenesis of the hypotrichous ciliate, Gonostomum strenua, found in the soil of a hill in Qingdao (Tsingtao, 36°08’N, 120°43’E), People's Republic of China is described. Some characteristics (organization of the frontoventral cirral rows, origin of the primary primordium and arrangement of the marginal as well as transverse cirri) are sufficiently different from a closely related species Gonostomum affine to suggest that it is a separate species, though its body shape, nucleus and buccal apparatus are very similar to that of G. affine. A comparison of the infraciliatures of the two species is necessary since morphological characteristics alone are sometimes insufficient for species separation.     

Cold microgradients elicit adaptive behavior in isotropically cooled, inert populations of Oxytricha bifaria (Ciliophora, Hypotrichida)

To complete our investigations on the oriented behavioral response of isotropically cooled, inert populations of Oxytricha bifaria to a warm thermal gradient, their physiological potentialities under cold microgradient conditions arising at 8.5 degrees C were studied. We monitored the behavior of the experimental populations, both at the level of the passing cold wave front, and afterwards when the thermal gradient stabilized, evaluating (i) their distribution in general, (ii) their relative centroids, (iii) the percentage of both backward creeping and immobile ciliates, and (iv) the numerical indices and rates of their creeping tracks. At the arrival of the cold wave front, the oxytrichas react immediately to the thermal stimulus, creep backwards at very high velocity along uninterrupted linear tracks, and thus move away from the cooling source. No specific behavioral response was ever observed in the static microgradient conditions. At 8.5 degrees C, despite their inertness, the ciliates are still able to behave adaptively, reacting immediately and orientatedly, once a directional factor (the cold-repelling thermal gradient) arises in an isotropic environment. This is similar to their behavior in the symmetric warm attracting thermal gradient.     

食物在贻贝棘尾虫(原生动物,纤毛虫)细胞内的消化过程

利用免疫荧光显微术、透射电镜及电镜酶细胞化学技术对食物在腹毛类纤毛虫-- 贻贝棘尾虫细胞内的消化过程进行了追踪观察.食物在进入消化腔隙的初期,外面包被着一层膜结构,但此外层膜很快被消化而消失;尔后食物在贻贝棘尾虫体内的消化过程可分为两种方式:一种方式为直接在消化腔隙内完成,此过程同1982年Kaul et al.和Das s et al.的报道;而另一部分食物的消化过程表现为食物逐步向细胞质内突入,以致最终完全被细胞质包围形成一被膜包裹的圆泡状结构;在此过程中,细胞质边缘突出众多含有酸性磷酸酶等物质的小囊泡结构,小囊泡与食物融合,其内的酸性磷酸酶等水解酶释放出来, 食物的表膜逐渐瓦解,个体逐渐变小,最终消化后的营养物质被释放到细胞的消化腔隙内; 这种食物通过胞口与胞咽达消化腔隙后,再由细胞质将其包裹形成的食物泡,我们称之为" 后成食物泡".这两种消化方式与贻贝棘尾虫的消化胞器为一腔隙结构相适应[动物学报 5 4(3):510-516,2008].