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排序方式: 共有179条查询结果,搜索用时 15 毫秒
171.
Arnon TI  Xu Y  Lo C  Pham T  An J  Coughlin S  Dorn GW  Cyster JG 《Science (New York, N.Y.)》2011,333(6051):1898-1903
Lymphocytes egress from lymphoid organs in response to sphingosine-1-phosphate (S1P); minutes later they migrate from blood into tissue against the S1P gradient. The mechanisms facilitating cell movement against the gradient have not been defined. Here, we show that heterotrimeric guanine nucleotide-binding protein-coupled receptor kinase-2 (GRK2) functions in down-regulation of S1P receptor-1 (S1PR1) on blood-exposed lymphocytes. T and B cell movement from blood into lymph nodes is reduced in the absence of GRK2 but is restored in S1P-deficient mice. In the spleen, B cell movement between the blood-rich marginal zone and follicles is disrupted by GRK2 deficiency and by mutation of an S1PR1 desensitization motif. Moreover, delivery of systemic antigen into follicles is impaired. Thus, GRK2-dependent S1PR1 desensitization allows lymphocytes to escape circulatory fluids and migrate into lymphoid tissues.  相似文献   
172.
173.
【目的】利用ISSR分子标记分析越南北部山区当地玉米种质材料的遗传多样性。【方法】采用ISSR技术和10个引物对从越南和老挝北部山区3个省收集的21份玉米种质材料即12份普通玉米和9份糯玉米的遗传多样性进行分析。【结果】在21份玉米种质材料中可以检测到108个ISSR片段,其多态性为100%。ISSR引物的多态性信息量值为0.10~0.39,每条引物平均为0.24;分辨力为14.29~0.48,平均每条为4.48。除ISSR-T1以外,所有ISSR引物在13份玉米材料中均产生特异性片段。根据聚类分析结果,使用70%的遗传相似性作为切割点,建立了玉米种质材料系统树,21份玉米种质材料被分为3大类。不同玉米材料的相似系数为0.52~0.90.【结论】ISSR标记可提供玉米种质遗传多样性信息,对越南玉米种质材料的收集、保护和育种具有重要作用。  相似文献   
174.
A 14-month-old intact, female Abyssinian cat was presented for chronic intermittent diarrhea and bilateral enlargement of the mammary glands. Gastrointestinal coccidiosis was diagnosed; therapy with sulfadi-methoxine was unsuccessful in the elimination of Isospora felis and clinical signs. Infection with Tritrichomonas foetus was diagnosed by fecal polymerase chain reaction (PCR) and successfully treated with ronidazole and dietary modification.  相似文献   
175.
From May 2013 to April 2014, 15 swine family‐run farms (17 pig litters) in two districts in Hung Yen province, near Hanoi, were virologically and epizootiologically monitored for swine influenza viruses (SIV) monthly. No SIV was isolated from nasal swabs. Maternal antibodies were detected in 10 litters, and seroconversion against SIV was detected in six litters. There was a marked difference in patterns of SIV transmission in the two districts. Van Lam district which has low density of swine with mainly smallholder farms had low intensity of SIV, with much of the infection caused by H1N1 2009 pandemic‐like viruses A(H1N1)pdm09, likely originated from humans. In contrast, Van Giang district, which has high swine density and larger farms, had high levels of typical SIV (triple reassortants H3N2 and H3N2 Binh Duong lineage viruses) circulating within swine. With one exception, the SIV lineages detected were those we concurrently isolated from studies in a large central abattoir in Hanoi. Influenza‐like illness symptoms reported by farmers were poorly correlated with serological evidence of SIV infection.  相似文献   
176.
MALDI-TOF-MS technology was used for identification of lipopeptide antibiotics produced by GEB3 strain,a derivative of Bacillus subtilis 168 which was transformed by lpaB3gene.The result showed GEB3 only produced lipopeptide antibiotic surfactin.The analysis by LC-MS demonstrated that GEB3 produced standard surfactin isoforms with side chain lengths of 13,14 and 15 carbon atoms.The bioactivity detection of surfactin indicated that the surfactin produced by GEB3 had inhibition effect on plant pathogens Rhizoctonia solani and Pyricularia oryzae.  相似文献   
177.
OBJECTIVE: To evaluate the effectiveness of a school nutrition programme on the weight gain and growth of Vietnamese schoolchildren. DESIGN: A proximate cluster evaluation of children in seven schools, in which fortified milk and biscuits supplying 300 kcal of energy were being given on school days, compared with children in 14 nearby schools with no feeding. All children were dewormed. SETTING: Twenty-one primary schools in Dong Thap Province, Vietnam. SUBJECTS: A cohort of 1080 children in grade 1 of 21 primary schools, and a cross-sectional interview of 400 children in grade 3. RESULTS: The programme gave children the equivalent of 90 kcal day- 1 over 17 months. t-Tests showed a small but statistically significant difference between groups in their average gain in weight and height: 3.19 versus 2.95 kg (P < 0.001) and 8.15 versus 7.88 cm (P = 0.008). A multiple-level model showed that the programme was statistically significant after controlling for clustering of children in schools, sex, age and initial underweight (P = 0.024). A significant impact on height was also seen in a regression model, but not when controlling for school. The most undernourished children tended to gain the least weight. There was no evidence of substitution. CONCLUSION: The programme had a small but significant effect on weight gain, but the most undernourished children benefited the least. Methods need to be developed to target them. This design may offer a means of estimating the impact of school feeding on growth in other programme settings.  相似文献   
178.
Zhang L  Yu W  He T  Yu J  Caffrey RE  Dalmasso EA  Fu S  Pham T  Mei J  Ho JJ  Zhang W  Lopez P  Ho DD 《Science (New York, N.Y.)》2002,298(5595):995-1000
It has been known since 1986 that CD8 T lymphocytes from certain HIV-1-infected individuals who are immunologically stable secrete a soluble factor, termed CAF, that suppresses HIV-1 replication. However, the identity of CAF remained elusive despite an extensive search. By means of a protein-chip technology, we identified a cluster of proteins that were secreted when CD8 T cells from long-term nonprogressors with HIV-1 infection were stimulated. These proteins were identified as alpha-defensin 1, 2, and 3 on the basis of specific antibody recognition and amino acid sequencing. CAF activity was eliminated or neutralized by an antibody specific for human alpha-defensins. Synthetic and purified preparations of alpha-defensins also inhibited the replication of HIV-1 isolates in vitro. Taken together, our results indicate that alpha-defensin 1, 2, and 3 collectively account for much of the anti-HIV-1 activity of CAF that is not attributable to beta-chemokines.  相似文献   
179.
This study describes an investigation to test whether genotypic differences for reproductive frost tolerance in field pea (Pisum sativum L.) can be measured in the field. The method involved individually tagging flowers or young pods at particular stages of development within 48 hr after a frost event and assessing pod survival and seed damage at maturity. Four field pea varieties were grown in 2011 in an experiment which measured the loss of pods following a specific frost event. This experiment also tested the impact of trellis and pathways sown with barley on the efficacy of the frost tolerance data. In 2012, an additional genotype was also tested and, in addition to pod loss, data were collected on seed damage in surviving pods. Results from both years showed significant genotypic differences. There was also a significant positive correlation between mean variety pod loss in 2011 and 2012 indicating reliability of this method across seasons.  相似文献   
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