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51.
B L Rothman M L Blue K A Kelley D Wunderlich D V Mierz T M Aune 《Journal of immunology (Baltimore, Md. : 1950)》1991,147(8):2493-2499
The CD44 molecule, also known as Hermes lymphocyte homing receptor, human Pgp-1, and extracellular matrix receptor III, has been shown to play a role in T cell adhesion and activation. Specifically, anti-CD44 mAb block binding of lymphocytes to high endothelial venules, inhibit T cell-E rosetting, and augment T cell proliferation induced by the CD2 or CD3-TCR pathways. We have characterized an anti-CD44 mAb (212.3) which immunoprecipitates a 90-kDa protein and is specific for CD44 as shown by peptide mapping and antibody competition studies. Interestingly, our studies with 212.3 demonstrate that this CD44-specific mAb completely inhibits T cell proliferation stimulated by the anti-CD3 mAb, OKT3. Inhibition is not a result of reduced cell viability, but is associated with 1) inhibition of IL-2 production, 2) inhibition of IL-2R expression, and 3) inhibition of OKT3-mediated increases in intracellular Ca2+ levels. In addition, 212.3 does not inhibit proliferation by the T cell mitogens PHA or PWM nor does it inhibit proliferation in a mixed lymphocyte reaction. Similar to other anti-CD44 mAb, 212.3 also augments T cell proliferation induced by mAb directed against the T11(2) and T11(3) epitopes of CD2. Thus, these studies describe a novel CD44-specific mAb (212.3) that inhibits T cell activation by OKT3 by blocking early signal transduction. Furthermore, these studies suggest that "receptor cross-talk" between the CD3-TCR complex and CD44 may regulate T cell activation. 相似文献
52.
Molecular characterisation of inter and intra-specific somatic hybrids of potato using randomly amplified polymorphic DNA (RAPD) markers 总被引:2,自引:0,他引:2
Eileen Baird Stephanie Cooper-Bland Robbie Waugh Michael DeMaine Wayne Powell 《Molecular & general genetics : MGG》1992,233(3):469-475
Summary Protoplast fusion allows the transfer of both mono- and polygenic traits between species that are sexually incompatible. This approach has particular relevance for potato, and somatic hybridisation has been used to introduce a range of disease resistance genes from sexually incompatible wild species into the cultivated potato gene pool. In addition, protoplast fusion allows the resynthesis of tetraploid genotypes from pre-selected diploid or dihaploid donor parents. A limiting factor for the efficient exploitation of this technology in potato breeding is the difficulty of unequivocally identifying nuclear hybrids (heterokaryons). In order to facilitate the identification of hybrids at an early stage following fusion, Randomly Amplified Polymorphic DNA markers (RAPDs) have been used to characterise molecularly both inter- and intra-specific somatic hybrids of potato. RAPD markers detect naturally occurring polymorphism in the donor genotypes and utilise short oligonucleotide primers of arbitrary nucleotide sequence in combination with the polymerase chain reaction (PCR). The exploitation of RAPDs in the characterisation of both somatic and sexual hybrids is discussed. 相似文献
53.
Nigel J. Kilby David L. Griggs Stephanie F. Berry 《Plant Cell, Tissue and Organ Culture》1992,28(3):275-280
Intra-population quinoline alkaloid profiles surveying quinine, quinidine, cinchonine and cinchonidine were determined for each of five populations of Cinchona ledgeriana grown as shoot-culture for 125 days. No significant difference in respect of mean alkaloid content between populations was detected. In contrast, there was considerable between-seedling variation in alkaloid content within each population. When nutrients were delivered to shoot-cultures in droplet form by means of an aerosol spray (as compared to the supply of nutrients direct from agar-or liquid-based reservoirs) alkaloid profile was greatly perturbed; most notable in this respect was a four-fold increase in the production of cinchonidine concomitant with a four-fold decrease in the production of cinchonine. These data are discussed with reference to the optimisation of quinoline alkaloid production by juvenile shoot-cultures of Cinchona ledgeriana. 相似文献
54.
J M Brewer J Arnold G G Beach W L Ragland J K Wunderlich 《Biochemical and biophysical research communications》1991,181(1):226-231
Chicken leg muscle parvalbumin was digested with cyanogen bromide or trypsin or trypsin after citraconylation. Peptides isolated by reverse phase HPLC at pH 7.0 were subjected to acid hydrolysis and amino acid analysis and, in some cases, sequencing. The chicken muscle parvalbumin amino acid sequence has ca. 80% sequence identity with alpha-type parvalbumins from mammalian (rabbit, human and rat) muscle. By contrast, the chicken thymus parvalbumin ("avian thymic hormone") sequence is very similar to reptile (turtle, salamander and frog) muscle beta-type parvalbumins. We hypothesize that the evolutionary appearance of the warm-blooded reptiles was accompanied by recruitment of the beta parvalbumin isozyme for promotion of lymphocyte maturation. 相似文献
55.
S.A. LEAROYD, R.G. KROLL AND C.F. THURSTON. 1992. The rates of reduction of seven redox dyes by 13 bacterial strains were measured and found to vary greatly between different bacterium/dye combinations. Phenazine ethosulphate and toluidine blue were the most rapidly reduced dyes by the majority of bacteria and resorufin and 2-hydroxy-1,4-naphthoquinone were reduced slowly, if at all. There was also considerable variation in the rates of reduction with any single dye/organism combination. Glucose stimulated the rates of endogenous dye reduction in about half of the organisms. For Bacillus cereus, Pseudomonas fluorescens and Escherichia coli , dye reduction was stimulated by a range of exogenous substrates but lactose, the primary available carbon and energy source in milk, had little effect. In Lactococcus lactis , dye reduction was stimulated by sugars but not by organic acids. Oxygen successfully competed with dye reduction in organisms containing respiratory chains, but with membrane fractions, dye reduction was more rapid than oxygen consumption. All the organisms showed little cytosolic dye reduction, except L. lactis which showed substantial rates of reduction of some dyes by this fraction. With the membrane fraction of E. coli and Ps. fluorescens , cyanide inhibited NADH and succinate-dependent dye reduction, Antimycin A inhibited lactate and succinate and rotenone had no significant effect, but inhibition was not always observed with membrane from both organisms. 相似文献
56.
Biological Control of Damping-Off of Alfalfa Seedlings with Bacillus cereus UW85 总被引:8,自引:4,他引:4
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Jo Handelsman Sandra Raffel Ellen H. Mester Lynn Wunderlich Craig R. Grau 《Applied microbiology》1990,56(3):713-718
We explored the potential of biological control of alfalfa (Medicago sativa L.) seedling damping-off caused by Phytophthora megasperma f. sp. medicaginis by screening root-associated bacteria for disease suppression activity in a laboratory bioassay. A total of 700 bacterial strains were isolated from the roots of field-grown alfalfa plants by using Trypticase soy agar. A simple, rapid assay was developed to screen the bacteria for the ability to reduce the mortality of Iroquois alfalfa seedlings that were inoculated with P. megasperma f. sp. medicaginis zoospores. Two-day-old seedlings were planted in culture tubes containing moist vermiculite, and each tube was inoculated with a different bacterial culture. Sufficient P. megasperma f. sp. medicaginis zoospores were added to each tube to result in 100% mortality of control seedlings. Of the 700 bacterial isolates tested, only 1, which was identified as Bacillus cereus and designated UW85, reduced seedling mortality to 0% in the initial screen and in two secondary screens. Both fully sporulated cultures containing predominantly released spores and sterile filtrates of these cultures of UW85 were effective in protecting seedlings from damping-off; filtrates of cultures containing predominantly vegetative cells or endospores inside the parent cell had low biocontrol activity. Cultures grown in two semidefined media had significantly greater biocontrol activities than cultures grown in the complex tryptic soy medium. In a small-scale trial in a field infested with P. megasperma f. sp. medicaginis, coating seeds with UW85 significantly increased the emergence of alfalfa. The results suggest that UW85 may have potential as a biocontrol agent for alfalfa damping-off, thus providing an alternative to current disease control strategies. 相似文献
57.
The Crustacea of some chalk streams in southern England 总被引:1,自引:1,他引:0
Stephanie F. Ham 《Hydrobiologia》1982,97(3):193-201
Records of Crustacea from chalk streams in southern England are described. Classification of sites suggested that flow regime was an important influence on the fauna and the distribution of individual species are discussed in this respect. 相似文献
58.
A modified latex agglutination (LA) test was compared with Gram-staining and counterimmunoelectrophoresis (CIE) for the rapid detection in the cerebrospinal fluid (CSF) of antigen to Haemophilus influenzae type b, Neisseria meningitidis groups A, B and C, Escherichia coli K1, Streptococcus pneumoniae and group B streptococci, seven frequent causes of bacterial meningitis in children. Of 50 CSF samples from patients with culture-proven bacterial meningitis 90% were correctly shown by the LA test to contain antigen of the responsible organism. Gram-staining revealed organisms in 80% of 45 of these samples. In 75% of the 40 samples that were of sufficient volume for CIE, positive results for the appropriate antigen were obtained. The concentration of antigen detected in the CSF by the LA test varied from undetectable to 800 000 ng/ml. Patients with a high concentration (more than 2000 ng/ml or a positive result at dilutions of CSF over 1/8) were significantly more likely to have a poor response to therapy (two died and two had persistent pleocytosis or bacteria in the CSF) than patients with a lower concentration (4/16 v. 0/18, P < 0.05). After appropriate therapy was begun the concentration of antigen fell dramatically, but measurable amounts of antigen persisted in the CSF for up to 6 days. The LA test detected bacterial antigen at concentrations 2 to 70 times below the lower limit detected by CIE. In seven additional patients who had received antibiotics before lumbar puncture was performed the LA test detected antigen from meningitis-causing bacteria even though cultures of the CSF were sterile. In another 145 patients who did not have meningitis the results of the LA test were negative. The LA test, done as described in this article, is easier to perform than CIE and should be a useful addition to the diagnostic tests carried out on the CSF of any patient suspected of having meningitis. 相似文献
59.
Stephanie Gordon Phillips Shiu-Lan Lui David M. Phillips 《In vitro cellular & developmental biology. Plant》1982,18(8):727-738
Summary Epithelial cells may relate to their basement membrane substrates via lectin-like interactions. In a model system for study
of this type of interaction, lectin-coated bacteriological plastic petri dishes were presented as substrates for epithelial
cell adhesion. Of 21 lectins tested by mixed agglutination against two epithelial cell types, Madin-Darby canine kidney (MDCK),
and human embryonic kidney cells (HEK), nine gave less than 5% rosettes and 12 gave 5 to 50% rosettes. Wheat germ agglutinin
(WGA) andGeodia cydonium lectin gave the highest percentage of rosettes. Wheat germ agglutinin was readily adsorbed to plastic surfaces and maintained
specificity in binding interactions. Both MDCK and HEK cells attached as well to WGA coated petri dishes as to conventional
tissue culture dishes. Furthermore, both spread over the lectin-coated surfaces. The MDCK cells grew to confluence and could
be subcultured and maintained indefinitely on such surfaces, although WGA in solution was toxic to the cells in concentrations
as low as 0.1 to 1.0 μg/ml. Cell attachment to WGA coated dishes was blocked by cycloheximide only if the cells had been preincubated
with the inhibitor for several hours. Cell attachment was not inhibited by pretreatment of cells with neuraminidase. Precoating
cells with WGA blocked binding to both WGA-coated surfaces and untreated tissue culture dishes. Cells attached to WGA-coated
dishes could not be readily dislodged by trypsin-EDTA for the first 2 h after subculture. By 4 h, attachment was again trypsin
sensitive, suggesting that the cells synthesized a trypsin-sensitive material that was laid down between the cell surface
and the WGA-coated dish. Regeneration of trypsin sensitivity was not blocked by cycloheximide.
This work was supported by Research Grant AG01986 from the National Institutes of Health, Bethesda, Maryland. 相似文献
60.
Synthetic leukotrienes (LT) C4 and D4 elicited concentration-dependent contractions of the guinea pig uterus between 10?8-10?6M, whereas LTE4 appeared 1000-fold weaker. The potencies of LTC4 and LTD4 were similar to that of acetylcholine and PGF2α but weaker than that of PGE2. The maximal contractions elicited by LTC4 and LTD4 were 66.0 ± 2.1% and 63.8 ± 4.6% that elicited by acetylcholine. FPL 55712 (10?5M) antagonized the uterine contractile activity of LTD4, while meclofenamic acid at 10?5M but not at 10?6M also antagonized the LTD4-induced contration. Radioimmunoassay of the uterine tissue bathing fluid following LTD4 indicated the variable presence of low concentrations of PGE2, PGF2α and TXB2. These results demonstrate the LTC4 and LTD4 possess significant uterine contractile activity, which may only partially be mediated indirectly via prostaglandin products. 相似文献