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161.
Juliette Morlon Martine Chartier Michel Bidaud Claude Lazdunski 《Molecular & general genetics : MGG》1988,211(2):231-243
Summary The complete nucleotide sequence of the colicinogenic plasmid ColA has been determined. The plasmid DNA consists of 6720 bp (molecular weight 4.48×106). Fifteen putative biological functions have been identified using the functional map previously determined. These include 11 genes and 3 DNA sites. Nine genes encode proteins of which 3 have been fully characterized. The replication region of ColA coding for RNAI and RNAII is highly homologous to that of ColE1 andClo DF13. The same holds true for the site-specific recombination region containing palindromic symmetry and involved in stable maintenance of the plasmids. A high percentage of homology has been detected for putative mobility proteins encoded by ColA and ColE1. The exclusion proteins are also highly homologous. 相似文献
162.
Julie Anderson Kirihara John P. Hunsperger Walter C. Mahoney Joachim W. Messing 《Molecular & general genetics : MGG》1988,211(3):477-484
Summary A methionine-rich 10 kDa zein storage protein from maize was isolated and the sequence of the N-terminal 30 amino acids was determined. Based on the amino acid sequence, two mixed oligonucleotides were synthesized and used to probe a maize endosperm cDNA library. A fulllength cDNA clone encoding the 10 kDa zein was isolated by this procedure. The nucleotide sequence of the cDNA clone predicts a polypeptide of 129 amino acids, preceded by a signal peptide of 21 amino acids. The predicted polypeptide is unique in its extremely high content of methionine (22.5%). The maize inbred line BSSS-53, which has increased seed methionine due to overproduction of this protein, was compared to W23, a standard inbred line. Northern blot analysis showed that the relative RNA levels for the 10 kDa zein were enhanced in developing seeds of BSSS-53, providing a molecular basis for the overproduction of the protein. Southern blot analysis indicated that there are one or two 10 kDa zein genes in the maize genome. 相似文献
163.
François Iborra Alain Raynal Michel Guerineau 《Molecular & general genetics : MGG》1988,213(1):150-154
Summary The relationship between the promoter length of the Kluyveromyces fragilis -glucosidase gene and the level of its expression in Saccharomyces cerevisiae was studied by gene fusion between deleted promoter fragments of various lengths and the promoterless -galactosidase gene of Escherichia coli. The removal of a region from position-425 to-232 led to a tenfold increase in the expression of the gene. The same results were obtained for the reconstructed -glucosidase gene with the same promoter length. It is likely that the deletion of this part of the promoter removes negative regulatory elements which are functional in Saccharomyces cerevisiae. This increase in activity is the main event which may explain the high increase in gene expression (60-fold) previously observed for an upstream deletion obtained during subcloning experiments of the -glucosidase gene. It is also shown that the expression of the gene greatly depends upon the nature of the recipient strain, the growth phase of the cell and that of the vector carrying it. 相似文献
164.
Apical cuttings of Solanum tuberosum L. cv. Sirtema were used al different stages of development to study long-distance transport of phosphate. The effects of two hormones, gibberellic acid (GA3 ) and abscisic acid (ABA), on this process were also investigated. Before tuberization, phosphate (32 P) supplied to a single leaf was transported preferentially in the young and growing parts of the plant: apical bud, young leaves and roots. After tuberization, the tuber became the principal site of phosphate accumulation. GA3 treatment (10−4 M) of the tuber as well as of the leaves led to reduced transport of 32 P into the tuber. By contrast, treatment of the tuber with ABA (10−4 M) did not change the 32 P distribution within the plant, while foliar spray with ABA greatly increased the transport into the tuber. The opposite effects of the two hormones on phosphate accumulation by tubers are discussed with regard to their opposite effects on the tuberization process. 相似文献
165.
Gibberellic acid (29 or 290 M) injected into drip irrigation lines significantly stimulated internode elongation of dwarf peas, and the 290-M soil treatment produced significantly taller plants than did the 29-M treatment. GA3 uptake may limit GA-induced internode elongation when GA3 is applied to soil, in contrast to results obtained for hydroponically grown plants, where uptake initially appeared to exceed the rate of hormone metabolism (andersonet al.). It is likely that biodegradation or chemical inactivation limited the plant-availability of GA3 in the soil. Degradation of moderate GA3 concentrations in a moist, aerobic loamy fine sand was nearly complete within five days, indicating that the inefficiency of soil applications may outweight the benefits provided by reducing labor costs associated with foliar-spray applications. 相似文献
166.
Elicitor-active preparations from the fungal pathogen of bean Colletotrichum lindemuthianum stimulated the accumulation of products characteristic of lipid peroxidation in treated bean tissues. Bean suspension cells treated with crude and purified elicitors accumulated `lipofuscin-like pigment' (LEP) and malondialdehyde. The accumulation of LFP after about 6 h of treatment coincided with the onset of visible browning and production of the bean phytoalexins kievitone, phaseollin, and phaseollinisoflavan. The induction of phytoalexins and accumulation of LFP were also triggered by treatments with generators of activated oxygen species, xanthine:xanthine oxidase and Fe:ethylenediaminedi-o-hydroxyphenylacetic acid. These data suggest that generation of active oxygen species may be involved in lipid peroxidation triggered by elicitors. 相似文献
167.
Glomerular basement membrane proteoglycans are derived from a large precursor 总被引:13,自引:6,他引:7
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D J Klein D M Brown T R Oegema P E Brenchley J C Anderson M A Dickinson E A Horigan J R Hassell 《The Journal of cell biology》1988,106(3):963-970
The basement membrane heparan sulfate proteoglycan produced by the Englebreth-Holm-Swarm (EHS) tumor and by glomeruli were compared by immunological methods. Antibodies to the EHS proteoglycan immunoprecipitated a single precursor protein (Mr = 400,000) from [35S]methionine-pulsed glomeruli, the same size produced by EHS cells. These antibodies detected both heparan sulfate proteoglycans and glycoproteins in extracts of unlabeled glomeruli and glomerular basement membrane. The proteoglycans contained core proteins of varying size (Mr = 150,000 to 400,000) with a Mr = 250,000 species being predominant. The glycoproteins are fragments of the core protein which lack heparan sulfate side chains. Antibodies to glomerular basement membrane proteoglycan immunoprecipitated the precursor protein (Mr = 400,000) synthesized by EHS cells and also reacted with most of the proteolytic fragments of the EHS proteoglycan. This antibody did not, however, react with the P44 fragment, a peptide situated at one end of the EHS proteoglycan core protein. These data suggest that the glomerular basement membrane proteoglycan is synthesized from a large precursor protein which undergoes specific proteolytic processing. 相似文献
168.
A series of monoclonal antibodies was prepared against tegumental and internal antigens of Fasciola hepatica by immunizing mice with whole adult-fluke homogenates prior to harvesting the splenic lymphocytes for fusion. Preliminary screening by the Indirect Fluorescent Antibody technique indicated the occurrence of discrete groups of monoclonals differing from one another in tissue-specificity but within which IFA labelling patterns were fairly consistent. Representative hybridomas for 5 of these groups were stabilized and used to produce ascites fluid in mice. By application of an immunogold labelling technique it was possible to map the distribution of antigens for which each monoclonal antibody had affinity throughout the tissues of 4-week and 12-week flukes. Several monoclonals specifically labelled antigenic determinants on the important tegumental antigen T1. However the distribution of gold colloid labelling suggested that epitopes other than that normally exposed to the infected host were recognized; and several monoclonals specifically attached to T1 antigen in the tegument of juvenile worms only. The glycocalyx of the gut and excretory system of flukes shared T1 antigenicity with the tegument. Monoclonal antibodies were produced against an internal immunogen associated with ribosomes and heterochromatin in active protein-producing cells, and against interstitial material of adult flukes. Monoclonals against antigens in parenchymal cell cytoplasm and in mature vitelline cells were recognized but the corresponding hybridomas were not stabilized. 相似文献
169.
A G Farr S K Anderson S C Braddy J L Mejino 《Journal of immunology (Baltimore, Md. : 1950)》1988,140(4):1014-1021
Using histochemical and immunocytochemical techniques, a lectin with nominal specificity for alpha-linked N-acetyl-D-galactosamine, Dolichos biflorus agglutinin (DBA), was found to preferentially label thymocytes with an L3T4-, Lyt-2- phenotype from fetal/newborn and adult mice. Through days 14 to 16 of gestation, virtually all thymocytes bound DBA, followed by a dramatic reduction of DBA labeling during the last 4 days of gestation, reaching adult levels of about 2 to 4% of total thymocytes. At later stages of fetal development, the DBA+ cells were confined to the subcapsular area of the thymus. This apparent loss of DBA+ cells was caused by an expansion of the thymocyte population not labeled with this lectin. Affinity purification of thymocyte cell surface components with insolubilized DBA indicated that virtually all of the lectin binding to fetal thymocytes was mediated by a 120-kDa glycoprotein. In addition to thymocytes, DBA also labeled about 5% of bone marrow cells from both normal or nude mice and a small population of spleen cells as well. These results suggest that this lectin may be useful to positively select for LT34-, Lyt-2- thymocytes, and, possibly, other immature populations within the T cell lineage. 相似文献
170.
Immune recognition of AIDS virus antigens by human and murine cytotoxic T lymphocytes 总被引:6,自引:0,他引:6
P Langlade-Demoyen F Michel A Hoffenbach E Vilmer G Dadaglio F Garicia-Pons C Mayaud B Autran S Wain-Hobson F Plata 《Journal of immunology (Baltimore, Md. : 1950)》1988,141(6):1949-1957
The CTL response to HIV was analyzed in humans and in mice. By using a novel and strictly autologous lymphocyte culture system, human CTL lines were established with PBL from seropositive asymptomatic donors and from patients suffering from AIDS or presenting AIDS-related complex. CTL from HLA-A2 donors recognize and kill murine P815 mastocytoma cells doubly transfected with the human HLA-A2 gene and the HIV env gene; they also kill HLA-compatible human macrophages infected with HIV. CTL specific for the HIV env Ag were also generated in BALB/c mice by immunization with syngeneic murine cells transfected with the HIV env gene. Human and murine HIV-immune CTL populations belong to the CD8 subset of T lymphocytes and are restricted by class I HLA or H-2 transplantation Ag, respectively, in the recognition of HIV env Ag. The two different experimental systems presented here can be used to study CD8 lymphocyte immunity against HIV. The murine model of CTL immunity offers the additional advantage of avoiding the manipulation of infectious virus isolates. 相似文献