ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1991.tb04795.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

ABSTRACTExoerythrocytic forms ofPlasmodium gallinaceumwere cultured in vitro using salivary gland sporozoites extracted from experimentally infectedAedes fluviatilismosquitoes. the host cells were macrophage precursors from chicken bone marrow. At various times after introduction of Sporozoites, the cultures were stained by Giemsa or by immunofluorescence assay (IFA) using anti‐sporozoite‐specific monoclonal antibodies (MAb). the time to complete parasite development in vitro was 50‐70 h. By 70 h, ruptured segmenters and free merozoites were visible within the cells. Inoculation of normal chickens with infected cultures induced parasitemia after a pre‐patent period of 10‐11 days. In vitro young exoerythrocytic forms, late schizonts that include the matured segmenters, and free merozoites shared common antigens with the sporozoites as revealed by IFA using anti‐sporozoite‐specific MAbs. Our data indicate that macrophages support development ofP. gallinaceumsporozoites and that the circumsporozoite proteins are present until Ac end of the primary exoerythrocyt

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1991.tb04796.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1991.tb04797.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

ABSTRACTGeosim was identified as the cause of a distinct earthy/grassy odour detected in cultures of a free‐living amoeba,Vannellaspecies. Volatile components of cell lysates were isolated and concentrated by the Closed Loop Stripping method. Capillary, gas chromatography/mass spectrometry was used to identify odorous compounds. Bacterial symbionts observed in the cytoplasm of the amoebae may be responsible for production of the geosmin. This appears to be the first report of odorous compounds associated with a free‐living protozoan and suggests that in some circumstances,Vannellasp. may contribute to taste and odour problems in drinking wa

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1991.tb04798.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

ABSTRACTEarlier studies showed thatLeishmania majorpromastigotes are sensitive to osmotic conditions. A reduction in osmolality caused the cells to shorten and to rapidly release most of their large internal pool of alanine. In this study some effects of hyper‐osmotic stress were examined. an increase in osmolality of the culture medium from 308 to 625 mOsm/kg caused only a small decrease in growth rate. When cells grown in the usual culture medium (308 mOsm/kg) were washed, resuspended in iso‐osmotic buffer, and subjected to acute hyper‐osmotic stress by addition of mannitol, the alanine content increased even in the absence of exogenous substrate. Promastigotes, depleted of alanine by a 5‐min exposure to hypo‐osmotic conditions, also synthesized alanine when resuspended in iso‐osmotic buffer. Washed cells resuspended in iso‐osmotic buffer consume their internal pool of alanine under aerobic conditions, Rates of consumption decreased on addition of mannitol, becoming zero at about 440 mOsm/kg. At higher osmolalities, alanine synthesis occurred. to estimate whether proteolysis could account for alanine synthesis in the absence of exogenous substrate, cells that had been grown with [1‐14C]leucine were washed and resuspended under hypo‐, iso‐, and hyper‐osmotic conditions and the amounts of14CO2and14C‐labelled peptides released in 1 h were measured. Little proteolysis occurred under these conditions, but the possibility that proteolysis was the source of the alanine increase, observed in response to hyper‐osmotic st

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1991.tb04799.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

ABSTRACTEarly development ofEimeria papillata(Apicomplexa) in the mouse was evaluated using Nomarski interference‐contrast and brightfield microscopy. Sporozoite‐shaped meronts, which were motile and contained a large posterior refractile body and a smaller anterior refractile body, were observed entering and leaving host cells in the jejunum of an experimentally infected mouse at 26 h post inoculation (HPI). However, early developmental stages were not observed in tissue of the duodenum, ileum, cecum and colon. the mean length and width of these meronts (n = 20) were 12.0 μm and 3.7 μm, respectively. Spherical or subspherical meronts containing crescent‐shaped merozoites were observed at

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1991.tb04800.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

ABSTRACTDynein arms and isolated dynein fromParamecium tetraureliaciliary axonemes are comparable in structure, direction of force generation, and microtubule translocation ability to other dyneins. In situ arms have dimensions and substructure similar to those ofTetrahymena.Based on spoke arrangement in intact axonemes, arms translocate axonemal microtubules in sliding such that active dynein arms are (‐) end directed motors and the doublet to which the body and cape of the arms binds (N) translocates the adjacent doublet (N+1) upward. After salt extraction, based on ATPase activity, paramecium dynein is found as a 22S and a 14S species. the 22S dynein is a three‐headed molecule that has unfolded from the in situ dimensions; the 14S dynein is single headed. Both dyneins can be photocleaved by UV light (350 nm) in the presence of Mg2‐, ATP and vanadate; the photocleavage pattern of 22S dynein differs from that seen withTetrahymena.Both isolated dyneins translocate taxol‐stabilized, bovine brain microtubules in vitro. Under standard conditions, 22S dynein, like comparable dyneins from other organisms, translocates at velocities that are about three times faster than 14S

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1991.tb04801.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

ABSTRACTThis report contains the newest directions for preparation of the synthetic nutrient medium for someTetrahymenaspecies that do not require lipids. In the standard mediumT. thermophila.strains SB 210 and 281, multiply at 37°C with doubling times of around 2 h and at 26°C around 5 h. We have established multiplication rates as functions of variations in the composition of the medium. In media in which all components are present at one‐third of the normal concentrations and only the essential amino acids are included, growth and multiplication become sharply dependent on glucose in strain SB 281. Such media may be used for selection and enrichment of certain specified cell li

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1991.tb04802.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

ABSTRACTThis report serves to introduce the symposium on food chains and food webs that is jointly sponsored by the Society of Protozoologists and the Phycological Society of America. A brief history of the field of aquatic microbial ecology is presented with an emphasis on the development of theoretical models that have directed the course of research — research that has shaped the development of new and more complex models of the present. the paper aims to provide historical background for all symposium participants and an introduction to the specific presentations of the four guest speaker

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1991.tb04803.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

ABSTRACTThe literature on discriminant feeding by planktonic protozoans using geometric and nongeometric criteria is reviewed with emphasis on recent studies that indicate phagotrophic protists can use information other than particle size or shape to sort among potential prey. Sufficient data are available for ciliates, aplastidic microflagellates, and phagotrophic dinoflagellates. Numerous representative taxa of all three groups have chemosensory capabilities, either to specific chemicals or to prey exudates, that modify their motility patterns resulting in aggregation or dispersal. Representatives of all three groups also have specific prey preferences. These considerations imply, but do not prove, selectivity in feeding through use of chemical cues. Although prey geometry is clearly a first‐order determinant of ingestion through passive mechanical selection, recent studies illustrate that planktonic ciliates and flagellates can use other criteria to discriminate among prey. the evidence clearly implicates use of chemical cues, most likely perceived through contact chemoreception. Filter feeders as well as raptors have such abilities indicating that feeding mechanisms per se do not imply limitations on feeding behavior. Evidence of considerable flexibility and complexity in chemoperceptive feeding suggests that we have only glimpsed the more detailed features of feeding behavior in aquatic protozoan

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1991.tb04804.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY