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Maize has traditionally been the main staple diet in the Southern Asia and Sub-Saharan Africa and widely grown by millions of resource poor small scale farmers. Approximately, 35.4 million hectares are sown to tropical maize, constituting around 59% of the developing worlds. Tropical maize encounters tremendous challenges besides poor agro-climatic situations with average yields recorded <3 tones/hectare that is far less than the average of developed countries. On the contrary to poor yields, the demand for maize as food, feed, and fuel is continuously increasing in these regions. Heterosis breeding introduced in early 90 s improved maize yields significantly, but genetic gains is still a mirage, particularly for crop growing under marginal environments. Application of molecular markers has accelerated the pace of maize breeding to some extent. The availability of array of sequencing and genotyping technologies offers unrivalled service to improve precision in maize-breeding programs through modern approaches such as genomic selection, genome-wide association studies, bulk segregant analysis-based sequencing approaches, etc. Superior alleles underlying complex traits can easily be identified and introgressed efficiently using these sequence-based approaches. Integration of genomic tools and techniques with advanced genetic resources such as nested association mapping and backcross nested association mapping could certainly address the genetic issues in maize improvement programs in developing countries. Huge diversity in tropical maize and its inherent capacity for doubled haploid technology offers advantage to apply the next generation genomic tools for accelerating production in marginal environments of tropical and subtropical world. Precision in phenotyping is the key for success of any molecular-breeding approach. This article reviews genomic technologies and their application to improve agronomic traits in tropical maize breeding has been reviewed in detail. 相似文献
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Akula N Midzak A Lecanu L Papadopoulos V 《Bioorganic & medicinal chemistry letters》2012,22(12):4139-4143
A homology model of the steroidogenic acute regulatory protein (STAR)-related lipid transfer (START) domain of STARD1 was built, and the cholesterol binding site was identified. Structure-based design studies were performed to identify small molecule inhibitors of the START domain. The lead compounds were selected based on cAMP-induced, but not 22R-hydroxycholesterol-supported, inhibition of steroid synthesis by 50% at 10 μM. The results obtained by molecular docking & dynamics show a good correlation between bioactivity, docking scores and calculated binding energies of ligand-protein complexes. The best active compounds will be optimized further and used to develop potential drugs to control excessive steroid formation. 相似文献
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Helena Svensson Veronica Olofsson Samuel Lundin Chakradhar Yakkala Stellan Bj?rck Lars B?rjesson Bengt Gustavsson Marianne Quiding-J?rbrink 《PloS one》2012,7(2)
Background
Colorectal cancer usually gives rise to a specific anti-tumor immune response, but for unknown reasons the resulting immunity is not able to clear the tumor. Recruitment of activated effector lymphocytes to the tumor is important for efficient anti-tumor responses, while the presence of regulatory T cells (Treg) down-modulate tumor-specific immunity. We therefore aimed to determine homing mechanisms and activation stage of Treg and effector T cell infiltrating colon tumors compared to cells from the unaffected mucosa in patients suffering from colon adenocarcinoma.Methodology/Principal Findings
Lymphocytes were isolated from unaffected and tumor mucosa from patients with colon adenocarcinoma, and flow cytometry, immunohistochemistry, and quantitative PCR was used to investigate the homing mechanisms and activation stage of infiltrating Treg and conventional lymphocytes. We detected significantly higher frequencies of CD25highFOXP3+CD127low putative Treg in tumors than unaffected mucosa, which had a complete demethylation in the FOXP3 promotor. Tumor-associated Treg had a high expression of CTLA-4, and some appeared to be antigen experienced effector/memory cells based on their expression of αEβ7 (CD103). There were also significantly fewer activated T cells and more CTLA-4+ conventional T cells susceptible to immune regulation in the tumor-associated mucosa. In contrast, CD8+granzyme B+ putative cytotoxic cells were efficiently recruited to the tumors. The frequencies of cells expressing α4β7 and the Th1 associated chemokine receptor CXCR3 were significantly decreased among CD4+ T cells in the tumor, while frequencies of CD4+CCR4+ lymphocytes were significantly increased.Conclusions/Significance
This study shows that CCR4+CTLA4hi Treg accumulate in colon tumors, while the frequencies of activated conventional Th1 type T cells are decreased. The altered lymphocyte composition in colon tumors will probably diminish the ability of the immune system to effectively attack tumor cells, and reducing the Treg activity is an important challenge for future immunotherapy protocols. 相似文献36.
Raf-induced vascular endothelial growth factor augments Kaposi's sarcoma-associated herpesvirus infection 下载免费PDF全文
Hamden KE Ford PW Whitman AG Dyson OF Cheng SY McCubrey JA Akula SM 《Journal of virology》2004,78(23):13381-13390
Recombinant green fluorescent protein encoding Kaposi's sarcoma-associated herpesvirus (rKSHV.152) infection of beta-estradiol stimulated human foreskin fibroblasts (HFF) or HFF/DeltaB-Raf([FF]):ER (expressing a weaker form of B-Raf) could be enhanced to levels comparable to that of HFF/DeltaB-Raf([DD]):ER cells by pretreating cells with soluble vascular endothelial growth factor (VEGF). Conversely, VEGF expression and infection efficiency typically observed in beta-estradiol stimulated HFF/DeltaB-Raf([DD]):ER cells could be lowered significantly by treating with VEGF small interfering RNA. In addition, we observed enhancement of the KSHV infection in HFF cells transfected with human VEGF(121). These results confirm the ability of Raf-induced VEGF to augment KSHV infection of cells. 相似文献
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Nodal explants of in vivo plants and in vitro seedlings of Wattakaka volubilis were cultured on Murashige and Skoog medium fortified with various concentrations of cytokinins — BA (0.5–5 mg l?1), KN (0.5–10 mg l?1),TDZ (0.05–1 mg l?1) either singly or in combination with NAA (0.1 mg l?1). KN proved best for inducing healthy shoots in both in vitro and in vivo derived explants. Maximum number of shoots (14.1±0.84) with 80% regeneration frequency was obtained from nodal explants of seedlings cultured on 5 mg 1?1 KN + 0.1 mg l?1 NAA. In vivo nodal explants produced a maximum of 4.2 shoots on MS medium fortified with 2 mg l?1 BA+0.1 mg l?1 NAA. The differentiated shoots from both could be rooted with 85% frequency on 1/2 strength MS medium (1% sucrose) with 0.6% agar + 1 mg l?1 IBA + 0.2 mg l?1 KN. Rooted shoots were transplanted to vermiculite-soil (3:1) mixture in polyethylene covered pots with 45% transplantation success. Peroxidase isozymes (native PAGE) analysis helped to verify the variation in regenerated plants. 相似文献
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Addition of betaine to the inductionmedium significantly enhanced the rapid formation ofsomatic embryos directly without callusing from maturefresh seeds of tea within two weeks of cultureinitiation. The induction response was furtherenhanced when ABA (7.5 mgl–1) was co-supplementedwith betaine in the induction medium. The rate ofinduction of somatic embryogenesis increased linearlywith external betaine concentration. Globular somaticembryo-like structures (embryoids) were observed in 4-week old cultures when inoculated on the inductionmedium without ABA and betaine. The positive effectof ABA on the induction process was found to bedependent on the presence of betaine in the medium. ABA alone in the medium could not bring the inductionstimulus in the explants; on the contrary, it provedinhibitory. The optimum response of ABA was observedwhen the medium was supplemented with 500 to1000 mgl–1 of betaine. Primary somatic embryosobtained in the presence of ABA and betaine were ableto produce secondary embryos. A conversion rate of15–20% was achieved upon transfer of somatic embryosof size 3–5 mm in diameter to the basal medium consistof half strength of macro nutrients, full strength ofmicro nutrients and vitamins of MS. Medium wasfurther supplemented with 100 mg l–1 each ofadenine hemisulfate sulphate and L-glutamine, 30 gl–1 sucrose, gelled with 7 gl–1 bitek agar. The plantlets regenerated by this procedure did notshow any visible abnormalities. This report for thefirst time details the potential use of betaine inplant tissue culture. 相似文献
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The crystal structure of the C-terminal domain of Vps28 reveals a conserved surface required for Vps20 recruitment 总被引:1,自引:0,他引:1
Pineda-Molina E Belrhali H Piefer AJ Akula I Bates P Weissenhorn W 《Traffic (Copenhagen, Denmark)》2006,7(8):1007-1016
The endosomal sorting complex I required for transport (ESCRT-I) is composed of the three subunits Vps23/Tsg101, Vps28 and Vps37. ESCRT-I is recruited to cellular membranes during multivesicular endosome biogenesis and by enveloped viruses such as HIV-1 to mediate budding from the cell. Here, we describe the crystal structure of a conserved C-terminal domain from Sacharomyces cerevisiae Vps28 (Vps28-CTD) at 3.05 A resolution which folds independently into a four-helical bundle structure. Co-expression experiments of Vps28-CTD, Vps23 and Vps37 suggest that Vps28-CTD does not directly participate in ESCRT-I assembly and may thus act as an adaptor module for downstream interaction partners. We show through mutagenesis studies that Vps28-CTD employs its strictly conserved surface in the interaction with the ESCRT-III factor Vps20. Furthermore, we present evidence that Vps28-CTD is sufficient to rescue an equine infectious anaemia virus (EIAV) Gag late domain deletion. Vps28-CTD mutations abolishing Vps20 interaction in vitro also prevent the rescue of the EIAV Gag late domain mutant consistent with a potential direct Vps28-ESCRT-III Vps20 recruitment. Therefore, the physiological relevant EIAV Gag-Alix interaction can be functionally replaced by a Gag-Vps28-CTD fusion. Because both Alix and Vps28-CTD can directly recruit ESCRT-III proteins, ESCRT-III assembly coupled to Vps4 action may therefore constitute the minimal budding machinery for EIAV release. 相似文献