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  • American Association for the Advancement of Science (AAAS)
  • Blackwell Publishing Ltd
  • 1
    Electronic Resource
    Electronic Resource
    In Vitro Excystation of Spironucleus muris (1996)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 43 (1996), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: . In vitro excystation of Spironucleus muris cysts, purified by sequential sucrose and Percoll gradients from mouse feces, was studied. Three in vitro excystation procedures, used for Giardia, were assessed to determine the most useful method. Excystation was monitored by light microscopy and subsequently characterized by transmission and scanning electron microscopy. Spironucleus muris excysted routinely at a level greater than 90% when induced in Hanks’ balanced salt solution containing sodium bicarbonate at pH 2.0 and transferred to Tyrodes’ salt solution as an excystation medium. Similarly, high rates of excystation were recorded after induction of S. muris cysts in 0.1 M potassium phosphate buffer (pH 7.0) with sodium bicarbonate and excystation in trypticase-yeast extract-iron medium (TYI medium) or phosphate-buffered saline. A lower rate and percentage of excystation were observed after induction of S. muris cysts in an aqueous hydrochloric acid solution (pH 2.0) followed by excystation in TYI medium. All excystation methods produced extremely active S. muris trophozoites with normal morphology. Nonexcysting S. muris cysts have a wall composed of an outer fibrous and an inner membranous portion. Following induction, numerous vesicles appeared in the peritrophic space. Excystation began by the cyst wall opening at one pole, and the anterior part of the trophozoite protruding from the cyst wall. The trophozoite emerged progressively from the cyst wall and the empty cyst wall appeared to collapse. Excysted trophozoites exhibited normal morphological features of S. muris trophozoites isolated from the mouse intestine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1996.tb02473.x
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  • 2
    Electronic Resource
    Electronic Resource
    Stabilization and Erosion Control Value of Oyster Cultch for Intertidal Marsh (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Restoration ecology 5 (1997), S. 0 
    Details
    ISSN: 1526-100X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Oyster cultch was added to the lower intertidal fringe of three created Spartina alterniflora marshes to examine its value in protecting the marsh from erosion. Twelve 5-m-wide plots were established at each site, with six randomly selected plots unaltered (non-cultched) and cultch added to the remaining (cultched) plots. Within each cultched plot, cultch was placed along the low tide fringe of the marsh during July 1992, in a band 1.5 m wide by 0.25 m deep. Marsh-edge vegetation stability and sediment erosion were measured for each plot from September 1992 to April 1994. Significant differences (p 〈 0.05) in marsh-edge vegetation change were detected at the only south-facing site after a major southwester storm. Significantly different rates of sediment erosion and accretion also were observed at this same site. Areas upland of the marsh edge in the cultched areas showed an average accretion of 6.3 cm, while noncultched treatment areas showed an average loss of 3.2 cm. A second site, with a northern orientation, also experienced differential sediment accretion and erosion between treatment type, caused instead by boat wakes that were magnified by the abutment of a dredge effluent pipe across the entire front fringe of the site. During this period we observed significant differences in sediment accumulation, with the areas upland of the marsh edge in the cultched treatment having an average accretion of 2.9 cm and the noncultched an average loss of 1.3 cm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1526-100X.1997.09710.x
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  • 3
    Electronic Resource
    Electronic Resource
    Organizational Prospects, Influence Costs, and Ownership Changes (1992)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of economics & management strategy 1 (1992), S. 0 
    Details
    ISSN: 1530-9134
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Economics
    Notes: We augment efficiency-based theories of ownership by including influence costs. Our principal conclusion is that the prospect of organizational decline and layoffs creates additional influence costs in multiunit organizations that would be absent if there was no prospect of layoffs and would be lessened or eliminated in focused organizations. This helps explain the tendency of firms to divest poorly performing units, as well as the pattern of sales of such units to firms already in businesses related to that of the divested unit.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1430-9134.1992.00009.x
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  • 4
    Electronic Resource
    Electronic Resource
    Electron Microscope Study of the Exoerythrocytic Form of Plasmodium gallinaceum in Thin Sections of Infected Tissue Cultures (1960)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 7 (1960), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The exoerythrocytic forms of Plasmodium gallinaceum in thin sections of infected tissue cultures have been examined with the electron microscope. It was seen that important changes occur in the fine structure of the parasite during the various phases of the cycle. The cytoplasm of the merozoites at the beginning and at the end of each cycle shows a great electron density due to a fine granulation. Larger granules are found at one pole of the parasite. The merozoites have a large nucleus in the center, and an oval body of great electron density at one pole, the significance of which is unknown. Short canaliculi can also be seen in the cytoplasm, but no mitochondria have been found.The cytoplasm of the schizonts shows a low electron density. It contains small particles scattered irregularly throughout its whole mass. The nuclei are not well defined; the oval body observed in the merozoites apparently has disappeared. Short canaliculi are present everywhere; however, mitochondria could not be identified with certainty.In the final phase of the cycle, in the rosette formations, the cytoplasm assumes again the fine granular structure. The future merozoites are grouped around a cytoplasmic core, with which they are directly connected. The whole segmenter is situated in a vacuole formation. In cross sections of the merozoites an opening in the central pole has been observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1960.tb00734.x
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  • 5
    Electronic Resource
    Electronic Resource
    Orientation of Paramecium Under the Conditions of Weightlessness (1993)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 40 (1993), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: . A cell culture of Paramecium with a precise negative gravitaxis was exposed to 4 times 10-6g during a parabolic flight of a sounding rocket for 6 min. Computer image analysis revealed that without gravity stimulus the individual swimming paths remained straight. In addition, three reactions could be distinguished. For about 30 s, paramecia maintained the swimming direction they had before onset of low gravity. During the next 20 s, an approximate reversal of the swimming direction occurred. This period was followed by the expected random swimming pattern. Similar behavior was observed under the condition of simulated weightlessness on a fast-rotating clinostat. Control experiments on the ground under hyper-gravity on a low-speed centrifuge microscope and on a vibration test facility proved that the observed effects were caused exclusively by the reduction of gravity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1993.tb04937.x
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  • 6
    Electronic Resource
    Electronic Resource
    Comparison of Ribosomal and Isozymic Phylogenies of Tetrahymenine Ciliates (1989)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 36 (1989), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: A recent analysis of sequence variations in ribosomal RNA's from 31 species of tetrahymenine ciliates groups them into 9 sets referred to as “ribosets.” These species associations are not well correlated with the distributions of distinctive morphological characteristics. The phylogenetic structure suggests that modem “pyriform” tetrahymenines may be paraphyletic survivors of primitive design and that the morphologically distinctive forms may include examples of convergent evolution of derived forms. Alternatively, the common ancestor may have been a polymorphic species that has lost its plasticity in some derived lineages. In an attempt to test the ribosomal phylogeny, we here compare it with a phytogeny based on isozymic variation. The main features of the ribosomal and isozymic phylogenies are similar. The carnivorous (macrostome-forming) species are widely scattered in both, as are the bacteriophagous pyriform species. Isozymic and ribosomal analyses are optimally useful, however, in different contexts. Isozymic variations can distinguish species that are ribosomally identical. Ribosomal variations provide more secure evaluations of distant relationships.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1989.tb02661.x
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  • 7
    Electronic Resource
    Electronic Resource
    New Wild Tetrahymena from Southeast Asia, China, and North America, Including T. malaccensis, T. asiatica, T. nanneyi, T. caudata, and T. silvana n. spp. (1985)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 32 (1985), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Tetrahymena of the T. pyriformis complex collected from varied habitats in Malaysia, Thailand, and The People's Republic of China include strains of the micronucleate species T. americanis and T. canadensis and the amicronucleate T. Pyriformis and T. elliotti. Two new breeding species are described—T. malaccensis from Malaysia and T. asiatica from China and Thailand. Two wild selfers from China and some of the amicronucleate strains from all three countries fall into isozymic groups similar to named micronucleate and amicronucleate species. The T. patula complex is represented by two groups of clones from Malaysia that fit the morphological description of T. vorax. They, however, have radically different isozymic electrophoretic patterns and both groups differ from those of previously described T. vorax. As their molecules indicate relationships to other “T. vorax” strains as distant as that between T. vorax and T. leucophrys, they are considered to be new species, T. caudata and T. silvana. A third new breeding species, T. nanneyi, was identified among strains previously collected in North America. Viable immature progeny were obtained from the new strains of the five breeding species. Maximum temperature tolerances were determined for the new strains of four of the breeding species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1985.tb03036.x
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  • 8
    Electronic Resource
    Electronic Resource
    Submicroscopical Aspects of Schizotrypanum cruzi in Thin Sections of Tissue Culture Forms (1960)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 7 (1960), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: In order to study the blepharoplast-kinetoplast region in the adult form of Schizotrypanum cruzi thin sections of this form, obtained in tissue cultures, have been examined with the electron microscope. It has been seen that the kinetoplast is contained in a large spherical, vacuole-like space, in hich its osmiophilic mass is more dispersed than in the leishmania and crithidia forms, where it is contained in a rectangular, almost linear space. The basal body of the flagellum has been found at the margin of the vacuole, although separated from it. A group of striae in parallel array has been found with regularity in all the trypanosome forms, similar to the structures of the parabasal body in other protozoa, or to the Golgi apparatus of metazoan cells. The significance of this structure for the parasite is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1960.tb00718.x
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  • 9
    Electronic Resource
    Electronic Resource
    Electron Microscopic Study of Trypanosoma cruzi Periplast in Tissue Cultures. I. Number and Arrangement of the Peripheral Microtubules in the Various Forms of the Parasite's Life Cycle (1976)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 23 (1976), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SYNOPSIS. In an electron microscopic study, counts of peripheral microtubules were made in spheromastigotes and trypomastigotes in tissue cultures of embryonic heart muscle cells. In interphase spheromastigotes there were, at the level of the nucleus, ∼ 114 microtubules; in dividing forms, there were ∼ 222. In trypomastigotes, the number of microtubules varied according to the level of the section—there were fewer than 40 tubules in the pointed ends of an organism, while in the central segment the number of these elements ranged from 60 to 115. The highest number of microtubules was found in the region containing the Golgi complex. The distance between the microtubules was constant, equalling 44 nm, even at the pointed ends of a trypanosome. This suggests that the microtubules course parallel to one another. Cross sections and randomly arranged, variable length, longitudinal sections of the tubules were noted around the kinetosomes in dividing organisms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1976.tb03792.x
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  • 10
    Electronic Resource
    Electronic Resource
    The Glyceryl Ethers of Paramecium Phospholipids and Phosphonolipids (1987)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 34 (1987), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Two glyceryl ethers, 1-O-hexadecyl glycerol and 1-O-cis-octadec-11-enyl glycerol, chimyl and paramecyl alcohol respectively, were quantified in total phospholipids and five glycerophospholipid classes from cells and cilia of the ciliated protozoon Parammecium tetraurelia. The ether content of 2-aminoethyl phosphonoglycerolipid was 85–90 mole %. Concentrations of ethers were greatest in the ethanolamine phosphonolipids 〉 phosphatidylcholines 〉 phosphatidylserines 〉 phosphatidylethanolamines 〉 phosphatidylinositols. The glyceryl ether concentrations in total cellular phospholipids increased with culture age in P. tetraurelia and P. multimteronucleatum cells. The glyceryl ether concentrations in the phospholipids of P. tetraurelia cilia remained constant from mid log to stationary phase of culture growth. Paramecium tetraurelia phospholipid glyceryl ether concentrations were made greater by supplementation of cultures with chimyl alcohol.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1987.tb03190.x
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