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61.
Stylet penetration activities of two aphid species were recorded electrically and compared with their efficiency of potato virus Y transmission. B. helichrysi (Kltb.) acquired the virus during 15% of single penetrations on infected leaves. These acquisitions were associated with the occurrence of cell membrane puncture by stylets, recorded during 44% of the penetrations. D. platanoidis (Schrank) punctured membranes during only 8% of penetrations, and its acquisition efficiency was less than 1%. The frequency with which aphids puncture cell membranes appears to partially determine their vector efficiency. 相似文献
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Faria M Spiller DG Dubertret C Nelson JS White MR Scherman D Hélène C Giovannangeli C 《Nature biotechnology》2001,19(1):40-44
Antisense oligonucleotides are designed to specifically hybridize to a target messenger RNA (mRNA) and interfere with the synthesis of the encoded protein. Uniformly modified oligonucleotides containing N3'-P5' phosphoramidate linkages exhibit (NP) extremely high-affinity binding to single-stranded RNA, do not induce RNase H activity, and are resistant to cellular nucleases. In the present work, we demonstrate that phosphoramidate oligonucleotides are effective at inhibiting gene expression at the mRNA level, by binding to their complementary target present in the 5'-untranslated region. Their mechanism of action was demonstrated by comparative analysis of three expression systems that differ only by the composition of the oligonucleotide target sequence (HIV-1 polypurine tract or PPT sequence) present just upstream from the AUG codon of the firefly luciferase reporter gene: the experiments have been done on isolated cells using oligonucleotide delivery mediated by cationic molecules or streptolysin O (SLO), and in vivo by oligonucleotide electrotransfer to skeletal muscle. In our experimental system phosphoramidate oligonucleotides act as potent and specific antisense agents by steric blocking of translation initiation; they may prove useful to modulate RNA metabolism while maintaining RNA integrity. 相似文献
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Molecular markers from a BAC contig spanning the Rdr1 locus: a tool for marker-assisted selection in roses 总被引:1,自引:0,他引:1
Anja Biber Helgard Kaufmann Marcus Linde Monika Spiller Diro Terefe Thomas Debener 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2010,120(4):765-773
We constructed a BAC contig of about 300 kb spanning the Rdr1 locus for black spot resistance in Rosa multiflora hybrids, using a new BIBAC library from DNA of this species. From this contig, we developed broadly applicable simple sequence
repeat (SSR) markers tightly linked to Rdr1, which are suitable for genetic analyses and marker-assisted selection in roses. As a source for the high molecular weight
DNA, we chose the homozygous resistant R.
multiflora hybrid 88/124-46. For the assembly of the BAC contig, we made use of molecular markers derived from a previously established
R. rugosa contig. In order to increase the resolution for fine mapping, the size of the population was increased to 974 plants. The
genomic region spanning Rdr1 is now genetically restricted to 0.2 cM, corresponding to a physical distance of about 300 kb. One single-stranded conformational
polymorphism (SSCP) and one SSR marker cosegregate with the Rdr1-mediated black spot resistance, while one SSR and several cleaved amplified polymorphic sequence or SSCP markers are very
tightly linked with one to three recombinants among the 974 plants. The benefits of the molecular markers developed from the
R. multiflora contig for the genetic analysis of roses and the integration of rose genetic maps are discussed. 相似文献
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Teng YK Verburg RJ Verpoort KN Diepenhorst GM Bajema IM van Tol MJ Jol-van der Zijde EC Toes RE Huizinga TW van Laar JM 《Arthritis research & therapy》2007,9(5):R106
In order to identify pathogenic correlates of refractory rheumatoid arthritis (RA), antibodies against anti-cyclic citrullinated
protein (ACPAs) were investigated in RA patients in whom the dysregulated immune system had been ablated by high-dose chemotherapy
(HDC) and autologous haematopoietic stem cell transplantation (HSCT). Six patients with refractory RA were extensively characterized
in terms of levels of total immunoglobulins, RA-specific autoantibodies (ACPAs and rheumatoid factor) and antibodies against
rubella, tetanus toxoid (TT) and phosphorylcholine before and after HDC plus HSCT. Additionally, the avidity of ACPAs was
measured before and after treatment and compared with the avidity of TT antibodies following repeated immunizations. Synovial
biopsies were obtained by arthroscopy before HDC plus HSCT, and analyzed by immunohistochemistry. In the three patients with
clinically long-lasting responses to HDC plus HSCT (median 423 days), significant reductions in ACPA-IgG levels after therapy
were observed (median level dropped from 215 to 34 arbitrary units/ml; P = 0.05). In contrast, stable ACPA-IgG levels were observed in three patients who relapsed shortly after HDC plus HSCT (median
of 67 days). Clinical responders had ACPA-IgG of lower avidity (r = 0.75; P = 0.08) and higher degree of inflammation histologically (r = 0.73; P = 0.09). Relapse (after 38 to 530 days) in all patients was preceded by rising levels of low avidity ACPA-IgG (after 30 to
388 days), in contrast to the stable titres of high avidity TT antibodies. In conclusion, humoral autoimmune responses were
differentially modulated by immunoablative therapy in patients with synovial inflammation and low avidity ACPA-IgG autoantibodies
as compared with patients with high levels of high avidity ACPA-IgG. The distinct clinical disease course after immunoablative
therapy based on levels and avidity of ACPA-IgG indicates that refractory RA is not a single disease entity. 相似文献