Biomedical subjects

Ning Jiang

Publications and source records attributed to Ning Jiang.

44 records · Page 3Linked to original sources

PubMed2003

Synthesis of triazole nucleoside derivatives.

5'-O-Mesyl-2',3'-O-isopropylidene ribonucleosides (4 and 12) were converted to their 5'-substituted nucleosides in good yields by reacted with NaN3 or KI. 2',3'-O-Isopropylidene ribonucleosides (3 and 11) were prepared in good yields from ribonucleosides 1 and 2 with a reaction mixture of acetone and triethyl orthoformate instead of using acetone diethyl acetal. Compound 1 or 2 was treated with 2-acetoxyisobutyryl halide (Cl or Br) to give 1-[2-O-acetyl-3-halo-3-deoxy-5-O-(2,5,5-trimethyl-1,3-dioxolan-4-on-2-yl)-beta-D-xylofuranosyl]-1,2,4-triazole-3-carboxamide (19, 22, and 23) in high yields. Instead of using 2-acetoxyisobutyryl bromide, the mixture of 2-acetoxyisobutyryl chloride and NaBr was employed in the synthesis of 22 and 23. Treatment of 19 with an activated Zn/Cu couple and deprotection gave 2',3'-anhydro nucleoside (21), and treatment of 22 and 23 with an activated Zn/Cu couple and a little of HOAc and deprotection gave corresponding 2',3'-unsaturated triazole nucleosides (24 and 25), respectively. The biological activity of the compounds (7-10, 15-18, and 24) was examined in human liver cancer cells (A-549), lung cancer cells (BEL-7402), and Flu-A cells.

Animals↗

PubMed2003

[Dynamic simulation of nitrogen application level effects on rice yield and optimization analysis of fertilizer supply in paddy field].

Field and water tank plot experiments were conducted in Zhejiang Province in 1999 to determine the effects of nitrogen application amount and times on rice growth and yield, and rice growth simulation model ORYZA-0 and nitrogen management module were used to establish a modified nitrogen effect-rice growth model. The simulated results presented a higher positive relationship with the measured results. According to the simulated and measured results, 160 kg.hm-2 was the economic nitrogen application amount for two rice varieties production, and the nitrogen application strategies were: 1) < 100 kg.hm-2 nitrogen fertilizer should be applied within 35 days after transplanting; 2) when the nitrogen application level was between 100-200 kg.hm-2, it should be applied within 45 days after transplanting; 3) if the nitrogen application amount exceeded 200 kg.hm-2, it should be put into paddy field within 60 days after transplanting; 4) as the nitrogen application amount increased, the nitrogen supply at the later rice growth stage should be increased. As for the second cropping rice, the more times the nitrogen applied in the field, the more closeness the rice yield reached the APCUM curve(optimized nitrogen curve) suggested. But in real rice production, it is impossible for farmers to adopt more times of N applying, since labor and cost will increase. Based on the experimental parameters and real rice production situation, the reasonable nitrogen application under 160 kg.hm-2 levels for high yielding second cropping rice was split into 4 times with fraction 0.2:0.3:0.3:0.2 at 5, 20, 30, 40 days after transplanting. The rice yield could reach 5,916 kg.hm-2, resulted in a 3.12% increase as compared with the yield under actual fertilizer application amount and timing.

Crops, Agricultural↗

PubMed2002

A role for the Cr2 gene in modifying autoantibody production in systemic lupus erythematosus.

Systemic lupus erythematosus is an autoimmune disease characterized by autoantibody production against nuclear Ags. Recent studies suggest that the Cr2 gene, which encodes for complement receptor (CR)1 and CR2, is important in disease susceptibility. Because the precise disease phenotype related to this gene, in isolation or in relation to other genetic loci, is not known, we analyzed C57BL/6 mice with a targeted mutation in Cr2 (C57BL/6.Cr2(-/-)) with or without a concomitant mutation in Fas (C57BL/6.lpr Cr2(-/-)). The Cr2(null) mutation in a C57BL/6.lpr background markedly increases the serum concentrations of IgG1 and IgG2b and the levels of antinuclear and anti-dsDNA Abs as compared with C57BL/6.lpr controls. There is also a trend for higher concentrations of IgG2a and IgG3. In contrast, isolated deficiencies in either these CRs or Fas have a limited effect in the production of anti-dsDNA Abs. Moreover, the Cr2(null) mutation does not affect other disease manifestations. These findings demonstrate that abnormalities in CR1 and CR2 may be linked to the production of autoantibodies by modifying the effect of other systemic lupus erythematosus susceptibility genes. Phenotypic expression of other disease manifestations need additional Cr2-independent genetic factors.

Animals↗

PubMed2002

Maspin sensitizes breast carcinoma cells to induced apoptosis.

Maspin, a novel serine protease inhibitor (serpin), suppresses the growth and metastasis of breast tumor in vivo. However, the underlying molecular mechanism is unclear. In the current study, we report the first evidence that endogenous maspin expression in mammary carcinoma cells MDA-MB-435 enhanced staurosporine (STS)-induced apoptosis as judged by the increased fragmentation of DNA, increased proteolytic inactivation of poly-[ADP-ribose]-polymerase (PARP), as well as the increased activation of caspase-8 and caspase-3. In parallel, recombinant maspin did not directly regulate the proteolytic activities of either caspase-3 or caspase-8 in vitro. Consistent with this result, maspin expressing normal mammary epithelial cells underwent more rapid STS-induced apoptosis as compared to breast carcinoma cells. Interestingly, maspin transfectant cells did not undergo spontaneous apoptosis in the absence of STS. Moreover, neither purified maspin protein added from outside nor endogenous maspin secreted to the cell culture media sensitized cells to STS-induced apoptosis. To investigate the structural determinants of maspin in its apoptosis-sensitizing effect, MDA-MB-435 cells were also transfected with maspin/PAI-1 and PAI-1/maspin chimeric constructs resulting from swapping the N-terminal and the C-terminal domains between maspin and PAI-1 (plasminogen activator inhibitor type 1). The resulting stable transfectant clones expressing maspin/PAI-1 and PAI-1/maspin, respectively, did not undergo spontaneous apoptosis, and were similarly inhibited as maspin transfectant cells in motility assay. Interestingly, however, expression of both maspin/PAI-1 and PAI-1/maspin in MDA-MB-435 cells failed to sensitize these cells to STS-induced apoptosis. Taken together, our evidence provides new insights into the complex molecular mechanisms of maspin that may suppress breast tumor progression not only at the step of invasion and motility, but also by regulating tumor cell apoptosis. The sensitizing effect of maspin on apoptosis is to be contrasted by the pro-survival effect of several other serpins.

Apoptosis↗

PubMed2002

Plant transposable elements: where genetics meets genomics.

Transposable elements are the single largest component of the genetic material of most eukaryotes. The recent availability of large quantities of genomic sequence has led to a shift from the genetic characterization of single elements to genome-wide analysis of enormous transposable-element populations. Nowhere is this shift more evident than in plants, in which transposable elements were first discovered and where they are still actively reshaping genomes.

DNA Methylation↗

PubMed2002

Dasheng: a recently amplified nonautonomous long terminal repeat element that is a major component of pericentromeric regions in rice.

A new and unusual family of LTR elements, Dasheng, has been discovered in the genome of Oryza sativa following database searches of approximately 100 Mb of rice genomic sequence and 78 Mb of BAC-end sequence information. With all of the cis-elements but none of the coding domains normally associated with retrotransposons (e.g., gag, pol), Dasheng is a novel nonautonomous LTR element with high copy number. Over half of the approximately 1000 Dasheng elements in the rice genome are full length (5.6-8.6 kb), and 60% are estimated to have amplified in the past 500,000 years. Using a modified AFLP technique called transposon display, 215 elements were mapped to all 12 rice chromosomes. Interestingly, more than half of the mapped elements are clustered in the heterochromatic regions around centromeres. The distribution pattern was further confirmed by FISH analysis. Despite clustering in heterochromatin, Dasheng elements are not nested, suggesting their potential value as molecular markers for these marker-poor regions. Taken together, Dasheng is one of the highest-copy-number LTR elements and one of the most recent elements to amplify in the rice genome.

Centromere↗

PubMed2002

Integration of Cot analysis, DNA cloning, and high-throughput sequencing facilitates genome characterization and gene discovery.

Cot-based sequence discovery represents a powerful means by which both low-copy and repetitive sequences can be selectively and efficiently fractionated, cloned, and characterized. Based upon the results of a Cot analysis, hydroxyapatite chromatography was used to fractionate sorghum (Sorghum bicolor) genomic DNA into highly repetitive (HR), moderately repetitive (MR), and single/low-copy (SL) sequence components that were consequently cloned to produce HRCot, MRCot, and SLCot genomic libraries. Filter hybridization (blotting) and sequence analysis both show that the HRCot library is enriched in sequences traditionally found in high-copy number (e.g., retroelements, rDNA, centromeric repeats), the SLCot library is enriched in low-copy sequences (e.g., genes and "nonrepetitive ESTs"), and the MRCot library contains sequences of moderate redundancy. The Cot analysis suggests that the sorghum genome is approximately 700 Mb (in agreement with previous estimates) and that HR, MR, and SL components comprise 15%, 41%, and 24% of sorghum DNA, respectively. Unlike previously described techniques to sequence the low-copy components of genomes, sequencing of Cot components is independent of expression and methylation patterns that vary widely among DNA elements, developmental stages, and taxa. High-throughput sequencing of Cot clones may be a means of "capturing" the sequence complexity of eukaryotic genomes at unprecedented efficiency.

Base Composition↗

PubMed2002

Dasheng and RIRE2. A nonautonomous long terminal repeat element and its putative autonomous partner in the rice genome.

Dasheng is one of the highest copy number long terminal repeat elements and one of the most recent elements to amplify in the rice (Oryza sativa) genome. However, the absence of any significant coding capacity for retroviral proteins, including gag and pol, suggests that Dasheng is a nonautonomous element. Here, we have exploited the availability of 360 Mb of rice genomic sequence to identify a candidate autonomous element. RIRE2 is a previously described gypsy-like long terminal repeat retrotransposon with significant sequence similarity to Dasheng in the regions where putative cis factors for retrotransposition are thought to be located. Dasheng and RIRE2 elements have similar chromosomal distribution patterns and similar target site sequences, suggesting that they use the same transposition machinery. In addition, the presence of several RIRE2-Dasheng element chimeras in the genome is consistent with the copackaging of element mRNAs in the same virus-like particle. Finally, both families have recently amplified members, suggesting that they could have been co-expressed, a necessary prerequisite for RIRE2 to serve as the source of transposition machinery for Dasheng. Consistent with this hypothesis, transcripts from both elements were found in the same expressed sequence tag library.

Base Sequence↗