ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1983.tb01402.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1983.tb01403.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

ABSTRACTUltrastructural observations of the cortically‐located mitochondria ofTetrahymena thermophilarevealed associations not only between the mitochondria and certain of the cortical microtubule bands, but also between the mitochondria and the epiplasm of the cortex. Most of the distal mitochondrial surface is close and parallel to the epiplasm; favorable views show bridge‐like structures spanning the 20–10 nm gap between the mitochondrion and the epiplasm.Previous studies have shown that the placement of mitochondria in the cortex appears to be determined by certain of the cortical microtubule bands. This study, however, shows that mitochondrion‐microtubule interactions account for only a small proportion of the total mitochondrial area associated with the cortex; the rest is accounted for by the epiplasm. A possible analogue of the spectrin layer of erythrocyte membranes, the epiplasm may be important in helping to arrange the intricately organized components of the ciliate cortex. Its involvement in apparently helping to “moor” mitochondria to their cortical sites is the first suggestion of any role in cell patterning played by t

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1983.tb01404.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

ABSTRACTThe fine structure of the trophozoite ofAcanthamoeba palestinensiswith a special emphasis on the Golgi complex, microbodies, and mitochondria has been examined. Golgi complexes are distributed throughout the cytoplasm but are most abundant in the perinuclear region. Usually two Goigi complexes are found in the same plane on opposite sides of the nucleus. One of them appears to be in an intimate association with the nuclear membrane. The region of contact contains compact cisternae, vesicles of various sizes, as well as granular and amorphous electron‐dense material. Structural changes in the nuclear envelope are also observed in this area. A structure consisting of a Golgi complex and electron‐dense microtubule organizing center, comparable to the centrosphere of otherAcanthamoebaspecies, has been observed. Microbodies, surrounded by a single unit membrane and containing a granular matrix and tubular inclusions, are scattered throughout the cytoplasm. These organelles, circular (∼1 μm in diameter) or ovoidal (∼1 μm in length and ∼0.5 μm in width) in section, have often an irregular outline. These microbodies are probably the morphological equivalent of peroxisomes and glyoxysomes. Most mitochondria show a typical structure including tubular cristae and intracristal inclusions. Occasionally mitochondria with two apposed double membranes running through the midline are found. Such atypical cristae have never been reported in small am

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1983.tb01405.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

ABSTRACTThe adoral ciliary zone of the rumen ciliates,Entodiniumspp., was observed topographically in the SEM. The upper side of the anterior end of the body was indented by the vestibulum, which had cilia arranged on its right wall and ribs along the left wall. The adoral ciliary zone could be divided into at least two arrangements. The outer ciliary zone had many membranelle‐like structures, which consisted of cilia arranged radially from the body axis. Each membranelle‐like structure consisted of two rows of about eight cilia each lining up in a single file. It was, however, different from a typical membranelle, because its cilia were connected with the vestibular cilia and were arranged not spirally but on a plane. These cilia extended toward the outside because of the projecting cytoplasm from which they originated. In contrast, the cilia of the inner ciliary zone were aggregated to form relatively unsystematic bundles. Since the vestibular opening was slanted on the upper side of the body, the ciliary bundles were thick on the lower side and sparse on the upper side of the body. Neither outer nor inner ciliary zones completely surrounded the vestibular opening. The ciliature started from the left side of the vestibular opening, encircled the lower side of the body, and entered the vestibulum from its right side. The functions of these two types of ciliary arrangements are discus

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1983.tb01406.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

RESUMECeTetradimorpha, rencontre en eau douce se présente soit sous forme sphérique pourvue de quatre flagelles et d'axopodes rayonnants, soit sous forme allongée avec a l'avant quatre flagelles associes a quatre axopodes et a l'arriére six a huit axopodes divergents. L'etude ultrastructurale révèle un cytosquelette axopodial de type centroplastidie comprenant un centroplaste lenticulaire homogéne, centre organisateur des quatre axopodes anterieurs et des six a huit axopodes posterieurs, auquel s'ajoutent les quatre cinetosomes des flagelles anterieurs. En outre, un deuxiéme éleément cytosquelettique incluant un microtubule associe chacun des quatre cinetosomes a l'axopode antérieur correspondant. Des cordons microfibrillaires réunissent axopodes et cinetosomes au niveau du centroplaste, puis a quelque distance du centroplaste les axopodes posterieurs. Les axonémes des axopodes comprenant de 5 a 30 microtubules sont constitues de triades, lorsqu'on peut détecter une organisation. Le noyau, a nucléole central est coince dans le cone axopodial posterieur, lui‐méme entouré des dictyosomes. Par l'organisation du cytosquelette, par la structure des kinétocystes, par la structure des flagelles dépourvus de mastigonémes tubulaires,Tetradimorphadiffére nettement deCiliophrys marina.Comme le prévoyait Davidson (1975), il represönte bien un des chainons dans la série évolutive des Héliozoaires centrohélidiens. Mais il ne présente guère d'affinites avec les Chrysomonadines considerees comme la souche des Héliozoaires. L'intéret de ce Protiste dans l'étude de la differentiation et de l'evolution du cytosquelette est également présente.ABSTRACTThis freshwater species ofTetradimorphahas a spherical body with four flagella and radiating axopods; it transforms into a pear‐shaped cell that anteriorly has four flagella intercalated between four axopods and posteriorly has six to eight divergent axopods. Ultrastructural study reveals an axopodial cytoskeleton of the centrohelidan type comprising an homogeneous lenticular centroplast which acts as MTOC for axopodial microtubules. A second skeletal element is a microtubular linkage between the kinetosomes and the axonemes of anterior axopods. A microtubule embedded in dense material diverges from near the base of each kinetosomes and parallels the distal portion of the axoneme of each anterior axopod. A microfibrillar envelope around the centroplast links the axopodial bases to the kinetosomes situated just above. Close to the centroplast, microfibrillar strands link the axopodial axonemes to the kinetosomes. Axopodial axonemes are composed of 5 to 30 microtubules irregularly arranged except for some that form equilateral triangles. The nucleus containing a central nucleolus is constrained within a cone formed by the axonemes of the posterior axopods and surrounded by dictyosomes. By the cytoskeletal organization, the structure of kinetocysts, and flagella wthout tubular mastigonemes,Tetradimorphadiffers obviously fromCiliophrys marina.As Davidson (1975) predicted,Tetradimorphais an intermediate link in the centrohelidan lineage: however, it lacks the characteristics of chrysomonads, the supposed ancestors of Heliozoa. The contribution of this genus to the study of the differentiation and the evolution of the cytoske

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1983.tb01407.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1983.tb01408.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

ABSTRACTThe trophont stage in the life cycle ofIchthyophthirius multifiliiswas studied in the electron microscope. Surface ridges contain up to 24 ridge microtubules, disposed as a ribbon. Kinetosomes show the classic morphology of 9 triplets of microtubules. Associated with each kinetosome is a kinetodesmal fibril, originating in proximity to triplets 5, 6, and 7, and having a 30 nm periodicity; 3 to 5 postciliary microtubules, originating between triplets 8 and 9; and up to 3 transverse microtubules, originating at triplet 4, as well as a parasomal sac. Each cell is partially enclosed by a system of 3 “unit” membranes: the outer limiting membrane, and the outer and inner alveolar membranes. The last two membranes define the alveolar sac. Mucocysts, each with a dense core, are present in large numbers. The contractile vacuole system includes the contractile vacuole, associated tubules and vesicles, injection canals, a discharge canal, and a pore. Microtubules abound in the walls of the contractile vacuole, injection and discharge canals, and in the region of the pores, where both ring and radial microtubular arrangements are noted. The ultrastructure suggests thatI. multifiliisis more closely related toTetrahymena pyriformisthan toParamecium aure

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1983.tb01409.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

ABSTRACTThe “mucigenic” or “muciferous” bodies ofPeranema trichophorumare further characterized here as unique extrusive organelles, the mucocysts. Intracellular and ejected mucocysts have characteristic shapes that may represent different developmental stages. Mucocysts found near the Golgi apparatus are membrane‐bounded, elongate, tubular structures with amorphous contents of low electron density. Subpellicular mucocysts are often aligned with pellicular striae and have dense contents, which are separated by an electron‐lucent zone from granular material at the tips. Ejected mucocysts are uniform in structure and consist of an inner tube with helical striations, an outer tube with a diamond‐shaped pattern, and a dense middle band. Fine fibrils, visible only after mucocyst discharge, emanate from the tips. Mucocysts may also protrude through the pellicle and discharge mucilaginous materials into the medium. Acid phosphatase activity is localized within the subpellicular mucocysts, suggesting that they may be involved in release of hydrolytic enzymes in

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1983.tb01410.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

ABSTRACTHeavy infections with enigmatic mobile organisms have recently been found in the blood of carp (Cyprinus carpio) in Central Europe. The organisms measure up to 15 μm, are variable in shape, and exhibit an unceasing twitching or dancing movement. Their developmental cycle starts with a primary cell enclosing a secondary cell. The former grows while the latter produces inside itself by a series of binary fissions and internal cleavages up to eight secondary cells, each of which encloses an inner (tertiary) cell of its own. In addition, up to four tiny cells with compact nuclei (“residual bodies”) also result from divisions of the secondary cells. Primary cells containing the products of the division of secondary cells finally disintegrate, releasing the secondary cells, which in their turn become new primary cells and repeat the cycle all over again. The structure and behavior of these organisms were so incompatible with existing ideas on myxosporean development that their myxosporean affinity was at first unrecognized. The final proof of their identity–appearance of myxosporean spores in sterile, experimentally infected hosts–is still to be presented. The interpretation of the myxosporean features of their life cycle (i.e., [1] the pericyte nature of the primary cell, [2]proliferation by disintegration of the pseudoplasmodial primary cell, [3] no rigidly fixed pattern in vegetative development), their ultrastructure (i.e., [1]characteristic bundles of microtubules and numerous free ribosomes in secondary cells, [2] lack of centrioles, [3]membranes enclosing the secondary cells within the primary cells), and facts on their epizootiology (i.e., [1] no success at transmission via leeches, [2]the occurrence of these organisms along withSphaerospora renicolaDykova and Lom) suggest that they are stages ofS. renicolafrom the kidney of carp. Similar mobile organisms were found in the blood of fry of two other fishes (Gobio gobiandTinca tinca) which are also hosts for aSphaerosporathat infects the kidney. This suggests that these organisms represent an early phase in the developmental cycle in the genusSphaerospora. The existence of cells enveloped one within the other (secondary and tertiary cells) in the developmental cycle, a characteristic myxosporean feature itself, is an intriguing parallel to similarly enclosed cells in sporogenesis of Paramyxea (Asce

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1983.tb01411.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY