ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1983.tb01023.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

ABSTRACT.Experiments have been carried out onGregarina garnhamito examine some of the factors that may be significant in gliding. Suspension of gregannes in Ficoll showed that substrate contact is essential. Reflection interference microscopy shows that there are fluctuating surface/substrate contacts, but it is not necessary for the whole of the undersurface of the cell to be in close contact with the substrate. Gliding is always accompanied by the formation of a mucus trail. The effects of the drugs amphetamine and ephedrine on mucus trail formation and gliding have been examined. Lateral undulations of the epicyte folds have previously been implicated in grcgarinc gliding, butG. garnhamidoes not exhibit lateral undulations of the epicyte folds as it moves. The folds are predominantly straight with indications of varicosities or swellings along the length of the folds. These observations are discussed in relation to gliding movement.

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1983.tb01024.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

ABSTRACT.The ciliated protozoonTetrahymena patulacan be grown in a chemically defined medium supplemented with a suitable lipid. High purity natural phosphoiipids; mono‐, di‐, and triglycerides: and free fatty acids are suitable lipids. The more complete lipids appear to serve simply as nutritionally convenient sources of fatty acids.T. patulacan also be grown in the synthetic medium supplemented with cholesterol or other sterols in lieu of fatty acid containing lipids. Supplementation with either ethanolamine or choline permits suboptimal growth of the ciliate in a lipid‐free synthetic medium. No other water soluble compound, of a variety that were tested, permitted growth of the ciliate in the lipid‐free

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1983.tb01025.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

ABSTRACT.Inhibition, inactivation, pH, and kinetic studies using both homogenates and purified lysosomal fractions ofParamecium caudalumand ofP. tetraureliawere carried out to examine the lysosomal acid phosphatase (AcPase) and its relationship to p‐nitrophenylphosphatase (pNPPase), glucose‐6‐phosphatase (G6Pase), and 5′‐nucleotidase (AMPase). The results generally support the idea thatParameciumcells contain a distinct lysosomal AcPase with a broad substrate specificity. The hydrolysis of glucose‐6‐phosphate (G6P) and adenosine 5′‐monophosphate (AMP) was shown to be due to this enzyme, suggesting that true G6Pase and AMPase may be lacking in these two species; however, some hydrolysis of AMP at pH 7.5 catalyzed by an unknown soluble enzyme distinct from alkaline phosphatase and Na+‐K+‐ATPase was observed. Since the hydrolysis of p‐nitrophenylphosphate (pNPP) at acid pH was also shown to be due to AcPase alone, pNPPase could be used as a rapid assay forParameciumAcPase. At an alkaline pH, however, this activity was catalyzed by an alkaline phosphatase located in the cytosol fraction.P. caudatumAcPase was shown to have kinetic properties similar to those of purified rat liver and human prostatic AcPase and to have relative substrate affinities in the order of G6P<β‐glycerophosphate

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1983.tb01026.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

ABSTRACT.A new procedure is described that utilizes Percoll gradients for purifying micronuclei (MIC) and macronuclei (MAC) fromTetrahymena thermophila. Separation of MIC from MAC during certrifugation in Percoll gradients occurs as a result of their difference in size rather than density. Three kinds of tests were used to evaluate the purity of the nuclei: visualization of the nuclei by light microscopy; examination of the nuclei by electron microscopy; and Southern blots of MIC and MAC DNA probed with the 5s rRNA genes or a fragment from the MAC extrachromosomal rDNA molecule. When examined under the light microscope, the isolated MIC and MAC have much lower nuclear cross contamination levels than previous methods have reported. MIC's contaminated with less than 1 MAC in 1000 MIC and MAC's contaminated with less than 1 MIC in 500 MAC can be routinely prepared. Quantitative analyses of electron micrographs gave higher estimates of cross contamination in our purified nuclei, which may, in part, be explained by the difficulty in identifying small MIC or MAC fragments. Southern blots of MIC and MAC DNA probed with 5s rDNA confirmed the level of MAC contamination in the MIC estimated by light microscopy during purification of the nuclei. The level of nucleolar contamination in the MIC was estimated at 10% by Southern blots of MIC and MAC DNA, derived from a heterokaryon with distinctive MIC and MAC Bam HI sites, using an rDNA probe.

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1983.tb01027.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

ABSTRACT.Cyclic AMP binding activity was determined in the ciliateTetrahymena pyriformisNT‐1 strain. The fractions having the binding activity were eluted in a single peak coincident with a protein kinase activity. Although metal ions were not essential for activity, the binding was slightly activated by Mg2+or Ca2+. The binding activity was sensitive to temperature, ionic strength, and pH of the reaction mixture and was decreased by treatment of the cytosol protein with trypsin or by heating at 100°C. The binding was specific for cyclic AMP, with an estimated apparent Kd of 40 nM. When the cyclic AMP binding activity in subcellular fractions was measured, an increase in the activity of ciliary, mitochondrial, and microsomal fractions was observed during the transition from the exponential to the stationary phase of cell growth, whereas no significant change occurred in the binding activity of the whole cell homogenate. These results suggest that the redistribution of cyclic AMP binding proteins may be implicated in the regulation of cyclic AMP concentration in the ce

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1983.tb01028.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

ABSTRACT.The pathway of de novo pyrimidine biosynthesis in the rodent parasitic protozoaBabesia rodhainihas been investigated. Specific activities of five of the six enzymes of the pathway were determined: aspartate transcarbamylase (ATCase: E.C. 2.1.3.2): dihydroorotase (DHOase: E.C. 3.5.2.3): dihydroorotate dehydrogenase (DHO‐DHase: E.C. 1.3.3.1); orotate phosphoribosyltransferase (OPRTase: E.C. 2.4.2.10); and orotidine‐5′‐phosphate decarboxylase (ODCase: E.C. 4.1.1.23). Michaelis constants for ATCase, DHO‐DHasc. OPRTase, and ODCase were determined in whole homogenates. Several substrate analogs were also investigated as inhibitors and inhibitor constants determined. N‐(phosphonacetyl)‐L‐aspartate was shown to be an inhibitor of the ATCase with an apparent K, of 7μM. Dihydro‐5‐azaorotate inhibited the DHO‐DHase (K, 16 μM) and 5‐azaorotate (Ki, 21 μM) was an inhibitor of the OPRTase. The UMP analog, 6‐aza‐UMP (Ki, 0.3 μM) was a potent inhibitor of ODCase, while lower levels of inhibition were found with the product. UMP (Ki, 120 μM) and the purine nucleotide, XMP (K1, 95 μM). Additionally, menoctone, a ubiquinone analo

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1983.tb01029.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

ABSTRACT.Leishmania tropicapromastigotes transport α‐aminoisobutyric acid (AIB), the nonmetabolizable analog of neutral amino acids, against a substantial concentration gradient. AIB is not incorporated into cellular material but accumulates within the cells in an unaltered form. Intracellular AIB exchanges with external AIB. Various energy inhibitors (amytal, HOQNO, KCN, DNP, CCCP, and arsenate) and sulfhydryl reagents (NEM, pCMB, and iodoacetate) severely inhibit uptake. The uptake system is saturable with reference to AIB‐and the Lineweaver‐Burk plots show biphasic kinetics suggesting the involvement of two transport systems. AIB shares a common transport system with alanine, cysteine, glycine, methionine, serine, and proline. Uptake is regulated by feedback inhibition and transinhi

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1983.tb01030.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

ABSTRACT.Polyurethane substrates were anchored near the surface of 14 lakes in the northern tip of the lower peninsula of Michigan. I wo substrates were removed from each take and taken to the laboratory after 1, 3, 6, 15, and 21 days of exposure. At the laboratory, one substrate was used for determining the number of species of diatoms and the other for protozoa. A cluster analysis of the matrix of Jaccard's coefficients for all diatom samples from all lakes showed that virtually all samples from any given lake consistently clustered together. This indicates that, with respect to species occurrence, distinct and compositionally stable diatom assemblages formed on the substrates in fewer than 21 days. Analysis of all protozoan samples from all lakes did not show such clustering, however, and the correspondence of clusters for protozoan and diatom communities for the 14 lakes was not particularly good. This suggests that the link between the two groups at the species level is not particularly strong during the early phases of artificial substrate colonization.

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1983.tb01031.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

ABSTRACT.Forty‐five axenically grown algal (sensu lato) species representing six divisions—that is. 13 Chlorophyceae, 14 Chrysophycophyta, five Dinophycophyta, seven Cryptophycophyta, two Rhodophycophyta, and four Cyanochloronta—were aseplicaily presented separately as potential food sources to the marine helerotrich ciliateFabrea salinaunder standardized algal number, medium, lighting, and temperature. The algae can be placed into three groups based on their effect on the intrinsic growth rate of the ciliate. Nutritious:Rhodomonas lens, cryptomonad LIS1,Dunaliella parva, Prasinodadus marinus, Chroomonas salina, D. tertiolecta, Chaeloceros galvestonensis, D. primolecta, Phaeodactylum tricornutum, D. salina, Isochrysis galbana, Cylindrothecaclosterium, cryptomonad strains M2, WH2&FSA,Chroomonas sp., P. lubricus, and Peridinium trochoideum.Maintamers: Cyanobacterium strain Tigriopus blue green,P. triquetum.Monochrysis lutheri, Exuviella gracilis, Platymonas tetrathele. Cyclotella caspa, Crypthecodinium cohnii, Prasinocladus C5strain,D. viridis, Nannochloris occulata, Tetraselmis gracilis, Anacystis marinum, Rhodosorus marinum, andThalassiosira pseudonana.Nonnutritious:Stichococcus immobilis, Hymenomonassp. strain 150,Syracosphaerasp. strain 181, Tetraselmis verrucosa, Thalassiosira fluviatilis, Microcoleus chthonoplastes, Synechococcus sp.,Pavlova gyrans, Prymnesium parvum, Coccolithus huxleyi, Olisthodiscus luteus, Amphidinium carterii, and Porphyridium aerugineum.There was no apparent relationship between a given taxon and the nutritional value of the group, with the possible exception of the Cryptophyco

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1983.tb01032.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY