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991.
Callus Induction and Plant Regeneration of Leaf Explants in Orychophragmus violaccus(L.) O. E.Schulz
Explants of Orychophragmus violaceus (L.) O. E. Schulz were acquired from young leaves which lower epidermis was stripped, Differentiation of calli in high frequency is in the case of that calli grown on B5 culture medium supplemented with 1 mg/l 2, 4-D should be transferred onto MS culture medium supplemented with 0.2 mg/l NAA. Effect of basic culture medium on the differentiation was discussed. In addition, protoplasts derived from calli of Orychophragmus violaceus were cultured, and small calli consisted of more than hundred cells had been obtained. 相似文献
992.
993.
994.
Shuai Zhang Honghua Su Weili Jiang Daowu Hu Intazar Ali Tianxing Jin Yizhong Yang Xiaoyan Ma 《Ecology and evolution》2021,11(20):13948
Complex interactions between symbiotic bacteria and insects ultimately result in equilibrium in all aspects of life in natural insect populations. In this study, abundance of principal symbiotic bacteria was estimated using qPCR in 1553 individuals of aphids, Aphis gossypii. Aphids were sampled from primary and secondary host plants—hibiscus and cotton. Hibiscus aphids were collected from 24 different locations in April, September, and November, whereas cotton aphids were collected between 2015 and 2017 from areas with wide variations in climatic conditions. About 30%–45% aphids were recorded with the most dominant symbiont, Arsenophonus. The other symbionts were in low frequency, and about 7% of aphids were noted with Hamiltonella, Acinetobacter, and Microbacterium, and 3% of aphids were verified with Serratia and Pseudomonas. Aphids infected with Hamiltonella, Arsenophonus, and Serratia can influence Buchnera densities. Hamiltonella has positive interaction with densities of Arsenophonus and Serratia. Almost 100% coinfection of Hamiltonella and Arsenophonus was detected in Xinxiang aphids and 50% coinfection was reported in aphids from North China, while no coinfection was detected in Hainan aphids. These findings describe the prevalence pattern and richness of core community of symbiotic bacteria in naturally occurring populations of A. gossypii and provide new insights for the study of symbiotic bacteria. 相似文献
995.
Qianru Li Jing Li Lei Sun Yun Sun Fei Zhao Pingping Liu Xin Peng Xiaoyan Xuan Yun Li Peng Wang Chen Tan Ying Du 《Bioscience reports》2021,41(10)
Inflammatory response mediated by immune cells is either directly or indirectly regulated by mesenchymal stromal cells (MSCs). Accumulating evidence suggests that thrombospondin-1 (TSP-1) is highly expressed in response to inflammation. In this work, we isolated and identified human thymic mesenchymal stromal cells (tMSCs) and detected the expression of TSP-1. We found that tMSCs expressed TSP-1 and Poly (I:C) or LPS treatment promoted the expression of TSP-1. Further, we isolated and identified exosomes originating from tMSCs (MEXs). Notably, exosomes derived from LPS-pretreated tMSCs (MEXsLPS) promoted the polarization of macrophages to M1-like phenotype and IL-6, TNF-α secretion as well as the pro-inflammatory differentiation of CD4+T cells into Th17 cells. Upon silencing the expression of TSP-1 in tMSCs, the pro-inflammatory effects of MEXsLPS were suppressed. Therefore, these findings uncovered TSP-1 as the principal factor in MEXsLPS pro-inflammatory regulation. 相似文献
996.
浑太流域洪涝灾害及其治理方略 总被引:1,自引:0,他引:1
抚顺、鞍山、辽阳等在内的中部城市群提供年用水量7.0×109m3的70%[5],对辽宁经济发展与生态环境建设具有至关重要的作用.本文试图剖析浑河、太子河洪涝灾害问题,找出其成因与特点,从生态与工程结合角度提出治理方略,为防洪减灾,振兴经济服务.2 洪涝灾害成因分析2.1 洪涝灾害的一般分析 洪涝灾害是天降暴雨和下垫面综合作用的结果.它通常依赖气象、水文地理和生态环境三方面因素.气象因素主要指暴雨,包括雨量、雨强和降雨落区.暴雨主要受大气环境制约,目前人类难以左右.然而,通过人工控制增减局地降雨… 相似文献
997.
W Zou R Mackenzie L Thérien T Hirama Q Yang M A Gidney H J Jennings 《Journal of immunology (Baltimore, Md. : 1950)》1999,163(2):820-825
The protective epitope of the type III group B streptococcal polysaccharide (GBSPIII) is length dependent and conformational. To obtain a more accurate characterization of the conformational epitope, ELISA inhibition and surface plasmon resonance studies were conducted on two GBSPIII-specific mAbs using a large panel of oligosaccharide probes. The results of the studies confirmed that 2 repeating units (RU) is the minimum binding unit and that, while increases in chain length from 2 RU to 7 RU caused further optimization of the epitope, it remained monovalent. A 3-fold increase in affinity was observed between 7 RU and 20 RU, which, by surface plasmon resonance studies on a Fab, was shown to be due to both further optimization of the individual epitope and the occurrence of multivalency of epitope. The data support our hypothesis that the conformational epitope is an extended helical segment of the GBSPIII. GBSPIII exists mainly in the random coil form, which structurally mimics short oligosaccharide self Ags, but it can infrequently and spontaneously form extended helices. Although not prevalent in GBSPIII, the immune system preferentially selects these helical epitopes because they are unique to the polysaccharide. Contrary to a previously proposed model of GBSPIII binding in which the binding of the first Ab propagates a continuum of helical epitopes, our binding kinetics are consistent only with the helical epitope's being discontinuous and infrequent. 相似文献
998.
阿霉素铁(Ⅲ)配合物与DNA结合作用的研究 总被引:2,自引:0,他引:2
应用吸收光谱法研究了阿霉素铁(Ⅲ)[ADM·Fe(Ⅲ)]与DNA的结合作用,结果表明ADM·Fe(Ⅲ)作为一个整体嵌入DNA碱基之间形成ADM·Fe(Ⅲ)·DNA三元复合物。应用荧光淬灭法得到了不同Na+浓度下ADM及ADM·Fe(Ⅲ)与DNA结合作用的结合常数(K)、结合位点距离(n)及标准自由能(ΔG),并根据多聚电解质理论将ΔG分解为电荷作用部分(ΔGpe)及非电荷作用部分(ΔGt)。结果表明ADM·Fe(Ⅲ)中铁离子直接参与了与DNA的作用,ADM·Fe(Ⅲ)较ADM更易与DNA结合,且结合更为紧密 相似文献
999.
1000.
Qizhao Ma Yangyang Pan Yang Chen Shuxing Yu Jun Huang Yaqi Liu Tao Gong Jing Zou Yuqing Li 《PLoS pathogens》2021,17(12)
Lysine acetylation is a frequently occurring post-translational modification (PTM), emerging as an important metabolic regulatory mechanism in prokaryotes. This process is achieved enzymatically by the protein acetyltransferase (KAT) to specifically transfer the acetyl group, or non-enzymatically by direct intermediates (acetyl phosphate or acetyl-CoA). Although lysine acetylation modification of glucosyltransferases (Gtfs), the important virulence factor in Streptococcus mutans, was reported in our previous study, the KAT has not been identified. Here, we believe that the KAT ActG can acetylate Gtfs in the enzymatic mechanism. By overexpressing 15 KATs in S. mutans, the synthesized water-insoluble extracellular polysaccharides (EPS) and biofilm biomass were measured, and KAT (actG) was identified. The in-frame deletion mutant of actG was constructed to validate the function of actG. The results showed that actG could negatively regulate the water-insoluble EPS synthesis and biofilm formation. We used mass spectrometry (MS) to identify GtfB and GtfC as the possible substrates of ActG. This was also demonstrated by in vitro acetylation assays, indicating that ActG could increase the acetylation levels of GtfB and GtfC enzymatically and decrease their activities. We further found that the expression level of actG in part explained the virulence differences in clinically isolated strains. Moreover, overexpression of actG in S. mutans attenuated its cariogenicity in the rat caries model. Taken together, our study demonstrated that the KAT ActG could induce the acetylation of GtfB and GtfC enzymatically in S. mutans, providing insights into the function of lysine acetylation in bacterial virulence and pathogenicity. 相似文献