共查询到20条相似文献,搜索用时 0 毫秒
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To avoid destruction by complement, normal and malignant cells express membrane glycoproteins that restrict complement activity.
These include decay-accelerating factor (DAF, CD55), membrane cofactor protein (MCP, CD46) and protectin (CD59), which are
all expressed on colonic adenocarcinoma cells in situ. In this study we have characterised the C3/C5 convertase regulators
DAF and MCP on the human colonic adenocarcinoma cell line HT29. DAF was found to be a glycosyl-phosphatidylinositol-anchored
70-kDa glycoprotein. Blocking experiments with F(ab′)2 fragments of the anti-DAF monoclonal antibody BRIC 216 showed that DAF modulates the degree of C3 deposition and mediates
resistance to complement-mediated killing of the cells. The expression and function of DAF were enhanced by tumour necrosis
factor α (TNFα) and interleukin-1β (IL-1β). Cells incubated with interferon γ (IFNγ) did not alter their DAF expression. Two
MCP forms were expressed, with molecular masses of approximately 58 kDa and 68 kDa, the lower form predominating. MCP expression
was up-regulated by IL-1β, but not by TNFα or IFNγ. Expression of DAF and MCP promotes resistance of colonic adenocarcinoma
cells to complement-mediated damage, and represents a possible mechanism of tumour escape.
Received: 18 July 1995 / Accepted: 4 January 1996 相似文献
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Yan HH Liu GQ Cheng ZK Li XB Liu GZ Min SK Zhu LH 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2002,104(2-3):177-183
In the course of transferring the brown planthopper resistance from a diploid, CC-genome wild rice species, Oryza eichingeri (IRGC acc. 105159 and 105163), to the cultivated rice variety 02428, we have isolated many alien addition and introgression
lines. The O. eichingeri chromatin in some of these lines has previously been identified using genomic in situ hybridization and molecular-marker
analysis. Here we cloned a tandemly repetitive DNA sequence from O. eichingeri IRGC acc105163, and detected it in 25 introgression lines. This repetitive DNA sequence showed high specificity to the rice
CC genome, but was absent from all the four tetraploid species with BBCC or CCDD genomes. The monomer in this repetitive DNA
sequence is 325–366-bp long, with a copy number of about 5,000 per 1 C of the O. eichingeri genome, showing 88% homology to a repetitive DNA sequence isolated from Oryza officinalis (2n=2x=24, CC). Fluorescent in situ hybridization revealed 11 signals distributed over eight O. eichingeri chromosomes, mostly in terminal or subterminal regions.
Received: 28 November 2000 / Accepted: 3 April 2001 相似文献
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A repetitive and species-specific sequence as a tool for detecting the genome contribution in somatic hybrids of the genus Medicago 总被引:1,自引:0,他引:1
Ornella Calderini Fulvio Pupilli Francesco Paolocci S. Arcioni 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1997,95(5-6):734-740
A highly repeated sequence (C300) was cloned from Medicago coerulea and its organization in the M. sativa-coerulea-falcata complex, M. arborea, and three somatic hybrids involving M. sativa, was investigated. Southern-blot analysis revealed a tandemly repeated array and a species-specificity of the sequence to
those species belonging to the complex. Various degrees of amplification of C300 were detected among the species of the complex
and the outcome in the somatic hybrids was dependent on parental composition. Sequence analysis revealed strong homology (96%)
of C300 with a clone (E180) previously isolated from M. sativa. As FISH analysis showed that C300 was dispersed along the chromosomes of Medicago spp., it should prove a valid tool for establishing the chromosome origin of somatic hybrids.
Received: 14 April 1997 / Accepted: 18 April 1997 相似文献
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Richard R. Arthur Neil A. Straus 《Biochimica et Biophysica Acta (BBA) - Gene Structure and Expression》1983,741(2):171-179
A new approach has been used to examine DNA sequence organization in the chicken genome. The interspersion pattern was determined by studying the fraction of labelled DNA fragments of different lengths that hybridized to an excess of short chicken repeated DNA sequences. The results indicate that chicken DNA has a pattern of sequence organization quite different than the standard ‘Xenopus’ or ‘Drosophila’ patterns. Two classes of unique sequences are found. One, 34% of the genome, consists of unique sequences approx. 4 kb long interspersed with repeated sequences. The second, non-interspersed fraction, 38% of the genome, consists of unique sequences found in long tracts, a minimum of approx. 22 kb in length. In an attempt to determine whether a relationship exists between DNA sequence organization and the distribution of structural genes we have isolated chicken DNA sequences belonging to different interspersion classes and tested each for the presence of structural genes by hybridization to excess poly(A)+ mRNA. Sequences complementary to poly(A)+ mRNA can be found with approximately the same frequency in both the non-interspersed fraction of the genome and a repeat-contiguous fraction enriched for interspersed sequences. 相似文献
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H. Thompson R. Schmidt A. Brandes J. S. Heslop-Harrison C. Dean 《Molecular & general genetics : MGG》1996,253(1-2):247-252
The middle repetitive fraction of the Arabidopsis genome has been relatively poorly characterized. We describe here a novel repetitive sequence cloned in the plasmid mi167,
and present in ∼90 copies in the genome of Arabidopsis thaliana ecotype Columbia. Hybridization analysis to physically mapped YAC clones representing Arabidopsis chromosome 4 revealed four mi167-hybridizing loci, all clustered near the centromere. No other loci were detected on YAC
clones covering chromosome 4. In situ hybridisation experiments to Arabidopsis chromosome spreads showed that mi167-hybridizing sequences are clustered at the centromeric heterochromatin of all five chromosomes;
on two chromosomes the hybridization appeared to be localised on one arm. Additional mi167-hybridizing loci were detected,
one of which was adjacent to a non-centromeric, heterochromatic region. This work supports the idea that the majority of middle
repetitive DNA in the Arabidopsis genome is clustered. It also adds to our understanding of the organization of the centromere of Arabidopsis chromosome 4.
Received: 19 February 1996 / Accepted: 30 June 1996 相似文献
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J. Preiszner I. Takács M. Bilgin J. Györgyey D. Dudits A. Fehér 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1994,89(1):1-8
A species-specific repetitive DNA fragment has been isolated from a genomic library of Solanum brevidens. Sequence analysis revealed a regular organization of three non-homologous subrepeats forming tandemly-arranged composite repetitive units. Interpretation of Southern hybridization patterns based on the known sequence data suggests that the isolated sequence element represents an abundant organization type, although the presence of simple tandem arrays of the subrepeats is also indicated. Seventy-four percent sequence similarity was found between one of the S. brevidens subrepeats (Sb4AX) and a satellite DNA (TGRI) localized as a subtelomeric repeat on almost all Lycopersicon esculentum chromosomes. Insitu hybridization indicated that, similarly to TGRI, the S. brevidens-specific repeats are located at the ends of the arms of several chromosomes. On the basis of the data obtained, a common ancestral sequence can be proposed for the tomato (TGRI) and the S. brevidens (Sb4AX) repeat however, the molecular organization of this element in these two species evolved in a basically different manner. 相似文献
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Tiyun Wu Ray Wu 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1992,84(1-2):136-144
Summary Repetitive DNA sequences in the genus Oryza (rice) represent a large fraction of the nuclear DNA. The isolation and characterization of major repetitive DNA sequences will lead to a better understanding of rice genome organization and evolution. Here we report the characterization of a novel repetitive sequence, CC-1, from the CC genome. This repetitive sequence is present as long tandem arrays with a repeat unit 194 bp in length in the CC-diploid genome but 172 bp in length in the BBCC and CCDD tetraploid genomes. This repetitive sequence is also present, though at lower copy numbers, in the AA and BB genomes, but is absent in the EE and FF genomes. Hybridization experiments revealed considerable differences both in copy numbers and in restriction fragment patterns of CC-1 both between and within rice species. The results support the hypothesis that the CC genome is more closely related to the AA genome than to the BB genome, and most distantly related to the EE and FF genomes. 相似文献
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S. T. Dougherty Connie J. Eaves William H. McBride Graeme J. Dougherty 《Cancer immunology, immunotherapy : CII》1997,44(3):165-172
In order to better define the role played by tumor-cell-derived macrophage-colony-stimulating factor (M-CSF) in regulating
the recruitment and phenotype of tumor-associated macrophages, Polyoma large T-transformed fibroblastoid cell lines, derived
from M-CSF-deficient osteopetrotic op/op mice and their phenotypically normal op/+ littermate controls, were inoculated into
SCID (severe combined immunodeficiency) recipients and both the proportion and phenotype of the macrophages present within
the tumors generated were determined. The results obtained indicate that, although tumors derived from M-CSF-deficient and
M-CSF-producing tumor cell inoculate contain a similar proportion of macrophages, the macrophages isolated from tumors lacking
M-CSF appear morphologically less mature and express lower levels of interleukin 1β, tumor necrosis factor α and FcRγII mRNA.
Taken together, these data suggest that, although M-CSF does not appear to play a critical role in determining the macrophage
content of these tumors, it does play a role in modulating the phenotype, and potentially the functional activity of the macrophages
present within the tumor microenvironment.
Received: 30 August 1996 / Accepted: 7 February 1997 相似文献
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Diverse manifestations of tumorigenicity and immunogenicity displayed by the poorly immunogenic B16-BL6 melanoma transduced with cytokine genes 总被引:4,自引:0,他引:4
Marjorie J. Arca John C. Krauss Scott E. Strome Mark J. Cameron A. E. Chang 《Cancer immunology, immunotherapy : CII》1996,42(4):237-245
We evaluated the in vivo response to the poorly immunogenic B16-BL6 (BL6) murine melanoma genetically altered to secrete
interleukin-2 (IL-2), IL-4, interferon γ (IFNγ) and granulocyte/macrophage-colony-stimulating factor (GM-CSF). Three parameters
were evaluated: (1) tumorigenicity, (2) vaccination of naive animals, and (3) assessment of antitumor reactivity of T cells
derived from tumor-draining lymph nodes (TDLN). Secretion of IL-2 abrogated the tumorigenicity of BL6, while IFNγ and IL-4
partially reduced tumorigenicity, and GM-CSF had no effect. Protective immunity to wild-type tumor challenge could not be
achieved by vaccination with irradiated cytokine-secreting tumors, although IL-2 and IL-4 secretion appeared to retard the
growth of the challenge inoculum significantly. An alternative method to evaluate the immunogenicity of the cytokine-secreting
tumors was to measure the ability of T cells obtained from TDLN to mediate regression of wild-type tumor in adoptive immunotherapy.
Neither IL-2 nor IFNγ secretion resulted in the induction of immune T cells. By contrast, GM-CSF and IL-4 secretion were found
to induce immune T cells in the TDLN with GM-CSF being superior to IL-4. The combined secretion of GM-CSF and IL-4 did not
lead to enhanced induction of immune T cells. GM-CSF secretion was found to up-regulate B7-1 expression in TDLN, consistent
with an increase in the population of antigen-presenting cells. These studies demonstrated that reduced tumorigenicity by
cytokine secretion did not correlate with increased immunogenicity. With the cytokines examined, there was limited capability
of developing protective immunity against the BL6 tumor. Nevertheless, GM-CSF and IL-4 secretion significantly enhanced T
cell immune reactivity to the poorly immunogenic BL6 tumor.
Received: 30 January 1996 / Accepted: 22 March 1996 相似文献
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We have developed a new strategy designated SIMF (Systematic Insertional Mutagenesis of Families), to identify DNA insertions
in many members of a gene family simultaneously. This method requires only a short amino acid sequence conserved in all members
of the family to make a degenerate oligonucleotide, and a sequence from the end of the DNA insertion. The SIMF strategy was
successfully applied to the large maize R2R3 Myb family of regulatory genes, and Mutator insertions in several novel Myb genes were identified. Application of this technique to identify insertions in other large gene families could significantly
decrease the effort involved in screening at the same time for insertions in all members of groups of genes that share a limited
sequence identity.
Received: 1 June 2000 / Accepted: 26 June 2000 相似文献
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The pachytene chromosomes of maize as revealed by fluorescence in situ hybridization with repetitive DNA sequences 总被引:13,自引:0,他引:13
C. C. Chen C. M. Chen F. C. Hsu C. J. Wang J. T. Yang Y. Y. Kao 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2000,101(1-2):30-36
A repetitive DNA sequence, ZmCR2.6c, was isolated from maize based on centromeric sequence CCS1 of the wild grass Brachypodium sylvaticum. ZmCR2.6c is 309 bp in length and shares 65% homology to bases 421–721 of the sorghum centromeric sequence pSau3A9. Fluorescence
in situ hybridization (FISH) localized ZmCR2.6c to the primary constrictions of pachytene bivalents and to the stretched regions
of MI/AI chromosomes, indicating that ZmCR2.6c is an important part of the centromere. Based on measurements of chromosome
lengths and the positions of FISH signals of several cells, a pachytene karyotype was constructed for maize inbred line KYS.
The karyotype agrees well with those derived from traditional analyses. Four classes of tandemly repeated sequences were mapped
to the karyotype by FISH. Repeats 180 bp long are present in cytologically detectable knobs on 5L, 6S, 6L, 7L, and 9S, as
well as at the termini and in the interstitial regions of many chromosomes not reported previously. A most interesting finding
is the presence of 180-bp repeats in the NOR-secondary constriction. TR-1 elements co-exist with 180-bp repeats in the knob
on 6S and form alone a small cluster in 4L. 26S and 5S rRNA genes are located in the NOR and at 2L.88, respectively. The combination
of chromosome length, centromere position, and distribution of the tandem repeats allows all chromosomes to be identified
unambiguously. The results presented form an important basis for using FISH for physical mapping and for investigating genome
organization in maize.
Received: 29 June 1999 / Accepted: 10 November 1999 相似文献
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In some species of hagfish, the phenomenon of chromosome elimination occurs during embryogenesis. However, only two repetitive
DNA families are known to be represented in chromosomes that are eliminated from somatic cells of the Japanese hagfish Eptatretus okinoseanus. Using molecular analyses, another germ line-restricted, highly repetitive DNA family has been detected in another Japanese
hagfish, Paramyxine atami. The repeat unit of this family, which is 83 bp long, has been designated “EEPa1”, for Eliminated Element of P. atami 1. DNA filter hybridization using EEPa1 as a probe revealed that this family is shared among several species and is conserved
in the germline DNA. Although eliminated, repetitive DNA that is shared interspecifically has not been reported in hagfish
species, cases of chromatin diminution and chromosome elimination processes have been described previously in other organisms.The
patterns and intensities of hybridization signals suggest that members of the repetitive DNA family defined by EEPa1 have
undergone concerted molecular evolution.
Received: 7 January 1997 / Accepted: 13 May 1997 相似文献
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L. Yuan Yasuhiro Kuramitsu Yongqin Li Masanobu Kobayashi M. Hosokawa 《Cancer immunology, immunotherapy : CII》1996,41(6):355-362
We studied mechanisms of immunosuppression caused by tumor-derived transforming growth factor-β (TGFβ) and restoration of
the immune response by treatment with bleomycin in rats bearing KDH-8 hepatoma. Interleukin-2 (IL-2) production from splenocytes
of KDH-8-tumor-bearing rats progressively decreased as the KDH-8 tumor grew. IL-2 production from concanavalin-A-stimulated
normal rat splenocytes was signficiantly inhibited by in vitro cultured KDH-8-tumor-cell-conditioned medium; this inhibition
could be blocked by neutralizing the conditioned medium with anti-TGFβ antibody. TGFβ activities were found in KDH-8-tumor-tissue-conditioned
medium without acid treatment and were found in tumor-cell-conditioned medium after acid treatment; TGFβ mRNA and TGFβ protein
were found in cultured KDH-8 tumor cells. These results suggested that the KDH-8-tumor-derived TGFβ might be involved in the
inhibition of IL-2 production from splenocytes. To determine whether bleomycin chemotherapy could reduce tumor-derived TGFβ
and restore the immune responses, we treated KDH-8 tumor-bearing rats with bleomycin (5 mg/kg, one shot) at an appropriate
time (before the occurrence of immunosuppression) resulting in a significiant reduction of TGFβ activity in KDH-8 tumor tissues
and restoration of IL-2 production from splenocytes of tumor-bearing rats; KDH-8 tumor growth ultimately regressed. In vitro
experiments also showed that TGFβ activity, mRNA expression, and protein synthesis in KDH-8 tumor cells were reduced by bleomycin
treatment, and that bleomycin-treated-KDH-8-tumor-cell-conditioned medium did not inhibit IL-2 production from normal rat
splenocytes. These results suggest that bleomycin treatment restored IL-2 production in tumor-bearing rats through reducing
the tumor-derived TGFβ.
Received: 12 June 1995 / Accepted: 3 November 1995 相似文献
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Marion-Gabriele Ott Daniela N. Männel Harald Gallati Matthias Goerig Ulrich Raeth 《Cancer immunology, immunotherapy : CII》1996,42(1):31-37
Tumor necrosis factor α (TNFα) and interferon γ (IFNγ) are important immunomodulators. They are capable of acting in a synergistic
manner on tumor cells in vitro and in vivo. In a clinical phase I study 13 patients with malignant ascites due to abdominal
spread of different primary tumors received intraperitoneally (i. p.) TNFα and IFNγ once weekly over 3 – 8 weeks in order
to evaluate the effect of locoregionally administered TNFα/IFNγ on ascites formation. Therefore some peripheral and local
immunological functional parameters of peripheral blood and malignant ascites were investigated. Mononuclear lymphocytes and
natural killer (NK) cell activity of peripheral blood and ascites, TNF-inhibitory activity, soluble p55 and p75 TNF receptors,
and prostaglandin E2 values in ascites were measured immediately before and 24 h after each TNFα/IFNγ infusion. Peripheral mononuclear lymphocytes
and NK activity decreased significantly 24 h after i. p. TNFα/IFNγ application. However, over the entire treatment schedule,
peripheral NK activity in all responders showed a continuous increase, when compared to pre TNFα/IFNγ treatment levels. In
contrast, NK activity in non-responders constantly decreased. In contrast to non-responders, TNF-inhibitory activity and soluble
p55 TNF receptor levels, determined in ascites, decreased in responders. Taken together, our findings suggest, that successful
locoregional i. p. TNFα/IFNγ therapy induces systemic immunological reactions possibly after saturation of soluble p55 TNF
receptors in ascites, which leads to an increase of peripheral NK activity.
Received: 28 September 1995 / Accepted: 16 November 1995 相似文献