摘要:

ABSTRACTGlycogen phosphorylase and synthase activities were detected in the sonic lysate of rumen ciliates of the genusEntodinium. The ciliate phosphorylase had the following properties. The pH optimum was narrow and centered at pH 5.9. The activity was maximum at 30°C; above 40°C a rapid inactivation occurred. The Kmvalue for glucose‐1‐phosphate (G‐1‐P) and for glycogen was 15 mM and 0.069% (w/v), respectively. NaF and ethylenediamine tetraacetic acid had no stimulative effect on the enzyme activity, though adenosine 3′,5′‐monophosphate and theophylline activated it. NaHSO3inhibited the enzyme activity at a concentration of 1 mM. The inhibition of glucose was noncompetitive for G‐1‐P. Glycolytic intermediates and nucleotides had a minor effect on phosphorylase activity. Glycogen synthase existed in two forms, glucose‐6‐phosphate dependent and independent forms: the proportion of the latter form increased with the decrease of reserve polysaccharide levels in the ciliates. Correlations between glycolytic enzyme activities included phosphorylase and synthase activities and reserve polysaccharide contents in the ciliates were determined, and a possible regulatory mechanism of polysaccharide synthesis and de

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1982.tb01331.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

ABSTRACTPrecursors of 2‐aminobutanoic acid (2‐ABA), found in the incubation medium of mixed rumen ciliate protozoa, were examined with washed or starved bacteria‐free ciliates. Threonine and methionine strongly stimulated the formation of 2‐ABA. Formation of 2‐ABA by direct conversion of threonine and dethiomethylation of methionine was confirmed by radiotracer experiments with [U‐14C]L‐threonine and [carboxyl‐14C] and [methyl

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1982.tb01332.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

ABSTRACTThe surface charge ofTritrichomonas foetuswas evaluated by means of the binding of colloidal iron hydroxide particles at pH 1.8 and cationized ferritin particles at pH 7.2 to the cell surface, as visualized by electron microscopy and by direct measurements of the electrophoretic mobility (EPM), of cells suspended in solutions of different ionic strength and pH. At pH 7.2,T. foetushas a negative surface charge with a mean EPM of −1.03 μmμs−1μV−1μcm. At lower pH, there is a decrease in the negative surface charge with an isoelectric point at pH 1.2. At higher pH (>9.0), there is an increase in the surface charge reaching an EPM of −2.5 μmμs−1μV−1μcm. These results indicate that the surface ofT. foetuscontains both negatively and positively charged dissociating groups. Binding of colloidal iron hydroxide and cationized ferritin particles throughout the cell surface of the protozoon was observed. Treatment ofT. foetuswith neuraminidase or trypsin reduced significantly the EPM of the cells. Enzyme‐treated cells recovered their normal EPM when incubated for 6 h in fresh culture medium by a process that is i

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1982.tb01333.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

ABSTRACTNineteen clones ofTrypanosoma cruziwere obtained as single‐cell isolates fromTriatoma infestans. Ten of the clones were isolates from a patient with chronic Chagas' disease; nine clones were isolates from a dog infected withT. cruzistrain CA‐I isolated originally from a chronic chagasic patient. The growth kinetics and peak modal Coulter volume of these clones were characterized. Significant inter‐ and intra‐group differences between growth rates and peak modal volumes were found. These data indicate that subpopulations and, consequently, genetic heterogeneity ofT. cruziexist in chronic chagasic patients. All of the clones infected vertebrate cells i

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1982.tb01334.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

ABSTRACTThe structure of the major protein of the pellicular membrane ofLeishmania tropicawas investigated. This protein is composed of two polypeptides, of ca. 50,000 d molecular weight, that were found to cross‐react immunologically with the α and β subunits of pig brain tubulin. The polypeptides and pig brain tubulin subunits were partially digested withS. aureusV8 protease, and the peptides obtained analysed by SDS‐polyacrylamide gel electrophoresis. A comparison of the patterns showed that the β subunits ofLeishmaniaand pig tubulin have very similar primary structures, while the α subunits have evolved divergently. These experiments demonstrate that the major polypeptides found in the pellicular membrane ofL. tropicaare α and β subunits of tubulin. Immuno‐electron microscopy indicates that the tubulin is located in the microtubules associated with the pellicular membrane ofLeishmania. Arrays of microtubules were prepared by nonionic detergent treatment of the cells and observed by electron microscopy after negative staining. Optical diffraction reveals a 5 nm spacing between protofilaments in the microtubule and a 4 nm axial periodicity corresponding to the tubulin subunits. The pitch of the shallow left‐hand three‐start helix is 12°. A distance of 47 nm separates each microtubule from the next. These data show that the dimensions and supramolecular organization of the tubulin subunits in the microtubules are identical in the pellicular membrane ofL. tropicaand in

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1982.tb01335.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1982.tb01336.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

ABSTRACTThe effects of irreversible inhibition of protein synthesis by pactamycin in either infective forms ofTrypanosoma cruzior mammalian host cells on cellular invasion by this human pathogen were investigated. Treatment of bloodstream forms ofT. cruziwith pactamycin markedly reduced their ability to bind either fibroblast‐like cells of monkey origin or myoblasts of rat origin. The number of amastigote forms that could be established intracellularly was also significantly decreased with respect to control values obtained when mock‐treated (medium alone) trypomastigotes were incubated with the cells. Pactamycin treatment also reduced the infectivity ofT. cruzitrypomastigotes for mice as evidenced by both significantly reduced parasitemia levels and mortality rates when compared with those of control mice infected with mock‐treated parasites. Inhibition of protein synthesis in the host cells neither prevented cell infection by untreated trypomastigotes nor altered the percentages of infected cells or the magnitude of the infection in vitro. These results indicate that protein synthesis is a requirement for cell invasion byT. cruziand that the parasite can establish itself and replicate within cells relying on its own protein synthesis ab

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1982.tb01337.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

ABSTRACTAmastigotes ofTrypanosoma cruziwere purified from overlays of infected Vero cell cultures by centrifugation over a discontinuous gradient of metrizamide. Pure amastigote preparations were usually recovered from the pellet under the layer of specific gravity 1.086. The isolated amastigotes grew in cell‐free ML‐15HA medium. Growth rate for the different strains ofT. cruziwere in the order Y>Tulahuan>CL. The generation time of amastigotes in ML‐15HA medium was 16.8, 18.0, and 26.4 h for the Y, Tulahuen, and CL strains, respectively, in the presence of 5% CO2) and 16.8, 31.2, and 36.4 h, respectively, in the absence of CO2. Intracellular amastigotes did not differ ultrastructurally from amastigotes from either the density‐gradient fractionation or culture in cell‐fr

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1982.tb01338.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

ABSTRACTHaemogregarina bigeminais redescribed from the blood of the marine fishBlennius pholis, and stages presumed to be those of the haemogregarine are recorded from the hematophagous praniza larva of the isopodGnathia maxillaris. At College Rocks, Aberystwyth, Wales, the main study area, a high incidence of infection occurred inB. pholis. No exoerythrocytic stages were observed in these fish, nor was sexual dimorphism of the gametocyte evident. As in an earlier study, ecological evidence favored transmission byG. maxillarisrather than by leeches. Gametocytes, syzygy, oocysts, sporoblasts, and sporozoites were identified in the anterior hindgut of the isopod. The stages observed inG. maxillarisare compared with those of other haemogregarines described from the digestive tract of leeches. Mention is made of an intraleucocytic haemogregarine of another fish,Crenilabrus melops.

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1982.tb01339.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

ABSTRACTUnicapsula seriolaen. sp. forms long plasmodia within the striated muscle fibers ofSeriola lalandioff eastern Australia. Its spores are composed of three valves, only one of which contains a developed polar capsule. Within the capsule, the filament makes 2 1/2–3 turns, and this criterion can be used to separateU. seriolaefrom the two other members of the genus. The flesh of infected fish disintegrates during slow cookin

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1982.tb01340.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY