摘要:

ABSTRACTFlow cytometry has been used to make direct measurements of rates of uptake of latex microspheres from dilute, monodisperse suspensions byTetrahymena pyriformis.Measurements were made for five different sizes of microspheres, ranging from 1.09 to 6.17 μm diameter. Fractions of cells in the population that did not ingest the microspheres offered were also determined. In addition, the size distributions, as indicated by the forward angle light scattering intensity which is measured by the instrument, were determined for the whole population and for the subpopulations of cells that did and did not ingest the particles, for each particle size used. It was found that the fraction of cells that did not ingest the particles was small and independent of particle size when this was less than about 2.7 μm, but increased with particle size when particle size was increased above this value. The so‐called maximum clearance rate, which can be calculated from the data, was found to increase monotonically with particle size if it were based only on those cells which actually ingested the particles offered. However, a plot of maximum clearance rate vs. particle size exhibited a maximum if the clearance rate were based on all cells present in the populat

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1990.tb01120.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

ABSTRACTThe course of malarial infection was compared in pregnant mice inoculated withPlasmodium bergheiat different stages of gestation. When 12–14 wk old, pregnant BALB/c mice were inoculated with 1 × 106ofP. bergheiNK65‐infected red cells at gestation day 0, 2, 4, 6, 8, 10, 12, 14 or 16, the mice inoculated on gestation days 6–12 expired 6.5 days after inoculation compared to 9.5 days in non‐pregnant mice. Parasitemia in these pregnant mice increased rapidly on day 4 after inoculation and anemia also developed earlier on day 5. However, the degree of parasitemia and anemia in the terminal stage of infection in these pregnant mice was milder than that of non‐pregnant controls. Blood urea nitrogen increased at the terminal stage although the degree of increase in mice inoculated on gestation days 6–10 was comparatively small. Pregnant malarial mice died earlier with less physiological changes than non‐pregnant controls. It was concluded that pregnancy makes the host susceptible to physiological changes cau

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1990.tb01121.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

ABSTRACTThe present study was undertaken to determine whether murine macrophage cell lines exhibited in vitro amoebicidal activity comparable to that elicited by activated murine peritoneal macrophages. Peritoneal macrophages activated in vivo by bacillus Calmette‐Guérin orPropionibacterium acnesdemonstrated significant cytolysis ofNaegleria fowleriamoebae. The macrophage cell line RAW264.7 also effected cytolysis of amoebae, but to a lesser extent than that elicited by activated peritoneal macrophages. However, the macrophage cell lines, J774A.1 and P388D1, did not exhibit amoebicidal activity. Macrophage conditioned medium prepared from RAW264.7 macrophages mediated cytolysis of L929 tumor cells but had no effect onN. fowleriamoebae. In addition, neither recombinant tumor necrosis factor nor recombinant interleukin‐1 exhibited amoebicidal activity. Scanning electron microscopy of co‐cultures revealed thatN. fowlerbound to activated peritoneal macrophages and RAW264.7 macrophages. These results suggest that RAW264.7 macrophages treated in vitro with lipopolysaccharide are similar to macrophages activated in vivo in that they effect contact‐dependent cytolysis ofNaegleria fowleriamoebae. The RAW264.7 macrophages are unlike primary macrophage cultures in that they either do not release soluble amoebicidal factors into the conditioned medium or they release insufficient qu

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1990.tb01122.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

ABSTRACTThe natural ecology of a heterosporous microsporidium,Amblyospora connecticuswas investigated at three different salt marsh habitats during 1986–1989. The parasite has a well‐defined seasonal transmission cycle that occurs regularly each year and intimately involves the primary mosquito host,Aedes cantator,and the intermediate copepod host,Acanthocyclops vernalis.In the spring, the microsporidium is horizontally transmitted from the copepod, where it appears to overwinter, to the mosquito via the ingestion of haploid spores produced in the copepod. Mosquitoes develop a benign infection, and females transmit the microsporidium transovarially to their progeny via infected eggs. Oviposition occurs during the summer and infected eggs hatch synchronously in the fall causing widespread epizootics. Infected larvae die, and the cycle is completed when meiospores are released into the pool and subsequently are eaten byA. vernalis,which reappears in the fall and early winter.Amblyospora connecticusthereby persists by surviving in one of two living hosts throughout most of its life cycle rather than in the extra‐corporeal environment. This represents an important survival strategy forA. connecticusas results show the salt marsh habitat to be a relatively unstable environment that is subject to periodic flooding and drying. The adaptive significance of utilizing an intermediate host in the life cycle is discussed as it directly facilitates transmission and enhances survival of the microspor

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1990.tb01123.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

ABSTRACTThe pattern of cytospindle assembly and the modifications of the microtubular cytoplasmic network during division ofParameciumare 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 ofParameciumis discusse

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1990.tb01124.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

ABSTRACTPolypeptide mating pheromones Er‐1 and Er‐2, purified from the supernatant ofEuplotes raikovicultures of mating type I and mating type II, respectively, were used to immunize mice and obtain monoclonal antibodies. Five hybridoma clones producing antibodies specific to the mating pheromones were selected. They were analyzed for immunospecificity by immunoperoxidase assay, immunoblotting, and for their efficacy in inhibition of mating pheromone activity. Monoclonal antibodies from two hybridoma clones recognized only the mating pheromone used as antigen; those from the other three clones reacted, to comparable extents, with both mating pheromones. On the basis of these results it was assumed that two immunogenic sites exist in Er‐1 and Er‐2, one specific and the other common to both mating phe

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1990.tb01125.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

ABSTRACTThe fatty acid profiles and contents of protozoa from the rumen fluid of cattle varied according to the type of diet consumed by their host. Changing from a high‐quality hay diet to a low‐quality hay diet (DA) decreased the proportions of saturated acids and increased the proportions of the unsaturated acids 18:1 cis‐9, 18:2 and 18:3 in neutral lipids (NL) and phospholipids (PL). Adding sucrose, urea and sulphur (SUS) to DA increased the proportions of branched chain acids in PL while addition of safflower oil increased polyunsaturated acids in PL and 18:1 trans‐11 in NL. Diet did not alter the PL fatty acid content of protozoa but oil supplement of DA resulted in a 10‐fold increase in the content of free fatty acids. The defaunating effect of oil supplement was partly reversed by SUS suggesting that factors other than the fatty acid content of cells are important in determining the toxicity of oil to rumen protozoa. The results indicate that the amounts of individual long‐chain fatty acids taken up by rumen ciliates are largely determined by their concentrations in ru

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1990.tb01126.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

ABSTRACTSpores ofNosema algeraeVávra and Undeen were subjected to various dosages of 254 nm ultraviolet radiation (UV). Very high dosages of UV were required to block germination. Germination was normal immediately after UV dosages of 0.2 to 1.0 J/cm2, followed by a delayed effect in which both percentage germination and the intrasporal concentration of trehalose decreased with time after UV exposure. Although a few spores were germinated, most of them were inactivated (rendered temporarily unable to germinate) by exposure to UV of 1.1 J/cm2. Ultraviolet radiation between 1.1 and 3.4 J/cm2stimulated spores to germinate. However, spores were completely unable to germinate immediately after exposure to dosages above 3.8 J/cm2. Ammonia had little effect on stimulation by UV but was inhibitory to germination after stimulation had occurred. These results demonstrate that UV behaves like a germination stimulus and are discussed in terms of the hypothesis that germination is initiated by the breakdown of barriers between trehalose and trehalase

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1990.tb01127.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

ABSTRACTTrypanosoma fallisin. sp. is described fromBufo americanusin Ontario. The parasite was observed in 65 of 94 toads examined. The trypanosomes were pleomorphic with respect to the age of infections, being longer and broader in early infections (during spring and summer) and shorter and more slender during late summer and autumn. They ranged in size from 38–76 μm in body length and 3–8 μm in width, with a free flagellum 6–30 μm long. Epizootiological and experimental evidence suggests that this trypanosome is transmitted to the toads by the leech,Batracobdella picta. Trypanosoma fallisiis morphologically similar toT. bufophlebotomidescribed inBufo boreasfrom California, but geographic isolation, host and vector differences as well as slight morphological differences indicate that speciation has occurred. Similar trypanosomes fromBufo americanus(which were identified asT. bufophlebotomi) in Michigan, are probablyT. fallisi.This species shares many ultrastructual features with trypanosomes of other lower vertebrates and also of

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1990.tb01128.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

ABSTRACTIn the cell cortex of the parasitic ciliateIchthyophthirius multifiliisdifferent kinds of cisternae were observed: the alveolar sacs, thick membrane cisternae and the endoplasmic reticulum. The thick membrane cisternae possess coated dilated rims and sometimes could be observed close to the endoplasmic reticulum. Using cytochemical techniques acid phosphatase, thiamine pyrophosphatase and nucleoside diphosphatase activities were detected in the thick membrane cisternae and in the alveolar sacs of trosphozoites. In the endoplasmic reticulum acid phosphatase activity was not detected and only very small amounts of thiamine pyrophosphatase and nucleoside diphosphatase reaction product were observed. After exit from the host, a reduction in acid phosphatase activity was evident in the alveolar sacs. At theront stage acid phosphatase activity is absent from these structures. However, high thiamine pyrophosphatase and nucleoside diphosphatase activities remain in the alveolar sacs during the whole life cycle. On the other hand, acid phosphatase, thiamine pyrophosphatase and nucleoside diphosphatase activities were detected in thick membrane cisternae of theronts. Based on the morphological aspects and enzymatic content the thick membrane cisternae of the cell cortex are designated as golgian‐like cisternae. The cytochemical results point out a relationship between the alveolar sacs and the Golgi comple

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1990.tb01129.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY