摘要:

ABSTRACTSorogena stoianovitchaeis an unusual ciliated protozoan with a life cycle characterized by the aggregation of individual trophic cells to form a multicellular sorogen that rises from the liquid culture medium surface by the secretion of a stalk. The noncellular stalk is a tapered, longitudinally furrowed structure composed of a fibrillar matrix that is initially hydrated, but with time dehydrates, the stalk becoming thin and brittle. This dehydration is of importance from the earliest stages of stalk formation since it results in the formation of the outer sheath‐like region of the stalk that appears to provide much of the support of the stalk. Cytochemical tests of the stalk for polysaccharides (including acidic mucopolysaccharides) and proteins are positive. Proteolytic enzymes degrade the stalk. Lectins specific for glucose and N‐acetyl‐D‐glucosamine bind to the stalk. Gas chromatography analysis detected the presence of fucose, glucose, glucosamine, and arabinose, as well as a variety of amino acids, predominantly glycine. The cytochemical and biochemical tests, the ultrastructural data, and the behavior of the stalk material suggest that the staik is composed of a matrix of complex protein‐polysaccharide

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1983.tb05332.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

ABSTRACTThe growth rate ofTetrahymena setosacells is stimulated significantly by as little as 0.1 μg and optimally by about 1 μg of ergosterol per ml of medium. Cell yields in the stationary phase are, however, not perceptibly affected by increasing sterol concentrations. Ergosterol, in concentrations that stimulate growth optimally, does not cause a reduction of tetrahymanol synthesis. The latter process is impaired only at much higher ergosterol concentrations. Epicholesterol and coprostanol inhibit ergosterol‐stimulated growth competitively. It is concluded that the trace amounts of sterol needed byT. setosado not serve to replace tetrahymanol but function in some other manner, probably unrelated to the control of membrane fluidity. This conclusion supports the views advanced earlier by Holz, Erwin, Wagner&Rosenb

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1983.tb05333.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

ABSTRACTOne third of a collection of clonedStylonychia pustulatamicronuclear DNA PstI fragments were found to be of a similar size, consistent with their being members of a repetitious sequence family with a repeat size of about 160 base pairs. Cross‐hybridization experiments confirmed that these small cloned fragments are related by sequence homology. Hybridization of the cloned repetitious sequences to PstI digested micronuclear DNA revealed a “ladder” of bands (step size = 160 base pairs), indicating that the repeats are found in tandem arrays. This is the first demonstration of highly repetitious, tandemly repeated sequences in a ciliated prot

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1983.tb05334.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

ABSTRACTIn early log phase cultures of several of the drug‐resistant mutants ofCrithidia fasciculatathat we have previously obtained, a high percentage of cells attach in pairs at the base of the flagellum. This process, which we have termed “flagellar adherence,” lasts for several hours in some cases and occasionally involves changes in cell morphology. The attachment occurs optimally in gently agitated cultures. Flagellar adherent pairs can be disassociated by vigorous agitation; the pairs reappear in the culture within one to three h after disassociation. These paired forms can be clearly distinguished from the normal cell division forms. Clones of flagellar adherent‐competent mutant strains are uniformly able to form these pairs in culture. A low percentage of flagellar adherent forms can be induced in wild type cells by glucose sta

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1983.tb05335.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

ABSTRACTThe erythrocytic developmental cycle ofPlasmodium falciparumcan be conveniently divided into the ring, trophozoite, and schizont stages based on morphology and metabolism. Using highly synchronous cultures ofP. falciparum, considerable variation was demonstrated among these stages in sensitivity to chloroquine. The effects of timed, sequential exposure to several clinically relevant concentrations of chloroquine were monitored by three techniques: morphological analysis, changes in the rate of glucose consumption, and changes in the incorporation of3H‐hypoxanthine into parasite nucleic acids. All three techniques gave essentially identical results. The trophozoite and schizont stages were considerably more sensitive to the drug than ring‐stage parasites. Chloroquine sensitivity decreased as nuclear division neared completion. The increase in chloroquine sensitivity was coincident with a marked rise in the rate of glucose consumption and nucleic acid synthesis. The rate of nucleic acid synthesis decreased as schizogony progressed while glucose consumption continued at high rates during this process. The degree of chloroquine sensitivity was not highly correlated with either metabolic activ

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1983.tb05336.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

ABSTRACTGossypol, a polyphenolic compound from the cotton plant, immobilizes and structurally alters culturedTrypanosoma cruziepimastigotes. Ultrastructural changes observed in gossypol‐treated parasites were first detected in the kinetoplast and mitochondrion. At 50 μM concentration, much disorganization was evident after 5 min of incubation. With 25 μM gossypol, the same effect occurred after 30 min. Most epimastigotes were rounded, containing various membranous structures that could not be related to known cell compone

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1983.tb05337.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

ABSTRACTNosema disstriae, a parasite of the forest tent caterpillar,Malacosoma disstria, was cultured with cell lines UMN‐MDH‐1(Malacosoma disstria), IPLB‐1075(Heliothis zea), and BTC‐32(Triatoma infestans). Infected cultured cells were used to infect the healthy cell lines. Electron micrographs of thin sections of 6‐day‐old cultures revealed infected cells that exocytosed vesicles containing vegetative and immature sporulating forms of the parasite. Some of these forms were believed to be responsible for intercellular transmission of the parasite. The spread of infection was augmented by culturing the cells at high densities; if the density was too low, there was little or no cross infection. Cross infection was inhibited, but not blocked completely, by high osmolality of the culture medium. The yield of spores from a confluent cell monolayer at the end of growth was generally 1–4 × 107per ml of

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1983.tb05338.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

ABSTRACTIndirect immunofluorescence using anti‐myosin rabbit sera showed myosin localized in a characteristic pattern at the anterior pole ofToxoplasma gondii. This polar fluorescent staining was abolished by pre‐absorption of the anti‐sera with myosin extracted from avian muscle. Both intracellular and extracellularT. gondiishowed similar patterns when formaldehyde‐fixed, but neither showed polar fluorescence when acetone was used as the sole fixative. Immunofluorescent staining of liveT. gondiirevealed no polar fluorescence, suggesting that myosin is not present on the outer parasite membrane. Anti‐myosin serum did not prevent host cell invasion and plaque formation in the presence of human complement. Inhibition of contractile proteins with cytochalasin D inhibitedT. gondiimotility and infectivity in a plaque formation assay. The pattern of polar fluorescence described here resembles the IgM‐associated polar staining frequently detected in human sera, but we believe it is a different phenomenon because human sera that showed such staining retained their activity after pre‐absorption with avian myosin. The unusual localization of myosin at the anterior pole ofT. gondiitachyzoites may play a role in the function of anterior organelles, which are thought to facilitate the invasion

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1983.tb05339.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

ABSTRACTBloodstream trypomastigote and culture procyclic (insect midgut) forms of a clonedT. rhodesiensevariant (WRATat 1) were tested for agglutination with the lectins concanavalin A (Con A), phytohemagglutinin P (PP), soybean agglutinin (SBA), fucose binding protein (FBP), wheat germ agglutinin (WGA), and castor bean lectin (RCA). Fluorescence‐microscopic localization of lectin binding to both formalin‐fixed trypomastigotes and red cells was determined with fluorescein isothiocyanate (FITC)‐conjugated Con A, SBA, FBP, WGA, RCA, PNA (peanut agglutinin), DBA(Dolichos bifloris), and UEA(Ulex europaeus)lectins. Electron microscopic localization of lectin binding sites on bloodstream trypomastigotes was accomplished by the Con A‐horseradish peroxidase‐diaminobenzidine (HRP‐DAB) technique, and by a Con A‐biotin/avidin‐ferritin method. Trypomastigotes, isolated by centrifugation or filtration through DEAE‐cellulose or thawed after cryopreservation, were agglutinated by the lectins Con A and PP with agglutination strength scored as Con A

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1983.tb05340.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

ABSTRACTMethods of transmission and the effects of temperature and mites on ageledeme development ofHerpetomonaswere examined in populations ofDrosophila melanogastermaintained in the laboratory.Herpetomonaswas observed in feces of infected adults taken from population cages and in the vomitus of clean flies shortly after feeding on a saline suspension of flagellates. Free‐swimming flagellates were found in the moist areas of food cups. AdultD. melanogasterbecame infected when they fed on flagellates taken from the endoperitrophic space, the ectoperitrophic space or the Malpighian tubules.At 25°C the flagellates infected approximately 90% of the host population within 20 days. The high transmission rate was prematurely disrupted if host populations were subjected to changes in temperature. Free‐swimming flagellates did not appear to be affected at these temperature changes. Food mites(Tyrophagus)established in the growth media of the fly nearly eliminated theHerpetomonasfromDrosophilapopulat

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1983.tb05341.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY