ISSN:1066-5234    

DOI:10.1111/j.1550-7408.1994.tb05926.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Membrane lipid compositions ofCryptosporidium parvumand Madin‐Darby bovine kidney cells, an epithelial‐like cell line commonly used to study coccidia in vitro, were analyzed using both thin‐layer chromatography and gas‐liquid chromatography. Phosphatidylcholine was the predominant lipid in bothC. parvumand Madin‐Darby bovine kidney cells, comprising 65% and 41% of the total phospholipids, respectively. Phospholipids ofC. parvumcontained twice the level of 16:0 and twenty‐fold more 18:2 than the Madin‐Darby bovine kidney cell line. We suggest that the parasite may be capable of sequestering specific complex membrane lipids at concentrations greater than those in the host cells. This study constitutes the first report of the lipid compositio

ISSN:1066-5234    

DOI:10.1111/j.1550-7408.1994.tb05927.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

The electrical membrane properties and the swimming behaviour of the freshwater ciliateBursaridium difficilewere studied by current clamp recordings and video analysis. The resting membrane potential was –45 ± 6 mV (mean ± SD, n = 80), and the input resistance and membrane capacitance were 109 ± 42 megaohms (MΩ) (n = 63) and 457 ± 150 picofarads (pF) (n = 42), respectively. Based on an estimated surface area of 6.8 × 10‐4cm2, the corresponding specific membrane resistance and capacitance are 7.4 × 104Ω× cm2and 0.7 μF/cm2.Bursaridium difficilegenerates spontaneous, all‐or‐nothing action potentials with a well‐defined threshold in normal medium. The spontaneous firing frequency was 0.22 ± 0.06 Hz (n = 80). The maximum rate of rise of the action potentials was less than 1 V/s, and they displayed a prolonged plateau phase (0.5–1 s). The action potentials were abolished in nominal Ca2+‐free solution and are thus Ca2+‐spikes. The swimming pattern ofBursaridiumin homogeneous surroundings is composed of forward swimming periods interrupted by regular, short periods of backward swimming followed by a change in the forward swimming direction. The turning frequency corresponded to the spontaneous firing frequency, and only forward swimming was observed in nominal Ca2+‐free solution. The periods of backward swimming activity are thus linked to the s

ISSN:1066-5234    

DOI:10.1111/j.1550-7408.1994.tb05928.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

ISSN:1066-5234    

DOI:10.1111/j.1550-7408.1994.tb05929.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

The nuclei of trophozoites and digestive cysts as well as mitotic nuclei of several species of the vampyrellidsVampyrella, Gobiella, Hyalodiscus, Arachnula, andLeptophryswere investigated by electron microscopy. Except for some species of the genusHyalodiscus, the vampyrellids are generally multinucleate. The nuclei of the trophozoite stage are in interphase. These nuclei are spherical, except for the genusArachnula, which reveals elongated nuclei. In digestive cysts of all vampyrellids the nuclei enlarge and the pars granulosa of the nucleoli becomes prominent. Karyokineses take place synchronously in older digestive cysts, which transform into reproductive cysts. The nuclei divide by closed intranuclear orthomitosis. In telophase the old nuclear envelope disintegrates and a new one is rearranged. Only in the genusLeptophrysthe nuclear envelope decomposes before telophase. Neither centrioles nor MTOC‐plaques have been found in any stage of mitosis. After karyokinesis the cell divides inside the cyst or when leaving the cys

ISSN:1066-5234    

DOI:10.1111/j.1550-7408.1994.tb05930.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Unlike its mammalian hosts, the opportunistic fungal pathogenPneumocystis cariniiharbors group I self‐splicing introns in its chromosomal genes encoding rRNA. This difference between pathogen and host suggests that intron splicing is a promising target for chemotherapy. We have found that intron splicing in vitro is inhibited by the anti‐Pneumocystisagent pentamidine and by a series of pentamidine analogues, as well as by some aminoglycosides, tetracycline, L‐arginine and ethidium bromide. Further studies will be needed to determine if this is the mechanism of action of pentamidine againstP. ca

ISSN:1066-5234    

DOI:10.1111/j.1550-7408.1994.tb05931.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Two strains ofNaegleria fowleriamoebae were studied when the amoebae were maintained in the same growth medium or in two different media. A weakly pathogenic strain ofN. fowleri, LEE, and a highly pathogenic strain, LEEmpCl, were compared for growth properties, the presence or absence of surface structures termed food cups, cytopathogenicity, cellular locomotion, susceptibility to complement‐mediated lysis and immunological relatedness by western immunoblot analysis when grown in Nelson medium or in Cline medium. The two different strains ofN. fowleri, LEE and LEEmpCl, were more similar in protein profiles and functional activity when both strains were grown in the same nutritional medium. Differences in growth, proteins synthesized, cytopathogenicity, susceptibility to complement lysis and rate of locomotion were noted when the same strain was grown in different media.Naegleria fowlerigrown in Cline medium demonstrated an increased rate of growth, an increase in its rate of locomotion, an increased resistance to complement lysis, and destroyed target nerve cells by contact‐dependent lysis. In contrast, the same strain of amoeba grown in Nelson medium showed slower growth, destroyed target cells by trogocytosis, and was less resistant to complement‐mediated

ISSN:1066-5234    

DOI:10.1111/j.1550-7408.1994.tb05932.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Reactivity of differentTrypanosoma cruzidevelopmental forms with purified Chagasic anti‐α‐galactosyl antibodies (anti‐Gal) was studied using epimastigotes from axenic cultures, trypomastigotes and amastigotes from infected Vero cell cultures, and an immunogold labeling method as observed by electron microscopy. Epimastigotes were poorly labeled, whereas extracellular trypomastigotes and amastigotes bound heterogeneously to the antibody with many cells being intensely labeled at the cell surface, including the membrane lining the cell body, the flagellum and the flagellar pocket. Parasites with poor labeling at the cell surface generally had several gold particles within the cell, mostly in cytoplasmic vacuoles. The Golgi complex of trypomastigotes was strongly labeled. Intracellular parasites were labeled at the parasite cell surface or within vacuolar structures. The expression inT. cruzi‐infected Vero cells of α‐galactosyl antigenic structures acquired from the parasite was shown by moderate labeling with Chagasic anti‐Gal of the membrane lining parasite‐free outward cell projections. The reactivity with purified anti‐Gal from healthy individuals at the same concentrations of Chagasic anti‐Gal was poor, with gold particles appearing in the nucleus and cytoplasm but not at the cell surface. It paralleled the labeling withBandeireae simplicifoliaIB‐4 lectin. The results provide a basis for autoimmune reactions involving anti‐Gal from ch

ISSN:1066-5234    

DOI:10.1111/j.1550-7408.1994.tb05933.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Herpetomonas roitmani, a trypanosomatid containing a bacterial endosymbiont, was cured by high doses of chloramphenicol. Wild‐type and cured flagellates were compared as to polysaccharide composition, nutritional requirements and cellular differentiation. Fucose (18.0%), xylose (15.7%), mannose (38.9%), galactose (10.8%), glucose (16.4%) and inositol (<1.0%) were identified as polysaccharide components of curedH. roitmanias assessed by gas‐liquid chromatography. However, the wild‐type strain displayed a markedly different sugar profile, in that xylose was absent and inositol preferentially synthesized, whereas the other monosaccharide components remained unchanged. Variations in nutritional pattern also occurred between both strains. The bacterial endosymbiont seems to provide the flagellates with nutritional factors, including usual amino acids, vitamins, purine (as adenine) and hemin. The process of cell differentiation was also significantly influenced by the endosymbiont. Opisthomastigote forms predominate (72.0%) in cured as compared with wild‐typeH. roitmani

ISSN:1066-5234    

DOI:10.1111/j.1550-7408.1994.tb05934.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Parathion, an organophosphorus insecticide, is highly toxic to the two free‐living marine dinoflagellatesProrocentrum micansEhrenberg (autotrophic) andCrypthecodinium cohniiBiechler (heterotrophic). To study its non‐antiacetylcholinesterase action we assessed its effect on the mitochondrial system, as shown by changes in intracellular ATP concentration and in rhodamine 123 fluorescence evaluated by image analysis. The technique of image analysis permits direct assessment of changes in the overall activity of mitochondria in living cells. Mitochondrial structures were also examined in the electron microscope. The three methods of investigation yielded complementary results. InP. micans, parathion noticeably altered mitochondria but did not significantly alter ATP concentrations. InC. cohnii, however, mitochondrial disturbance was slight, whereas ATP increased greatly. We think, therefore, that parathion has different effects on mitochondria in the two organisms, and in particular that it increases mitochondrial activity inC. coh

ISSN:1066-5234    

DOI:10.1111/j.1550-7408.1994.tb05935.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY