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[学术文献] Biochar amendment to further reduce methylmercury accumulation in rice grown in selenium-amended paddy soil 进入全文

Journal of hazardous materials

Methylmercury (MeHg) accumulation in rice is an emerging food safety issue in China and other countries; however, mitigation methods are scarce. Here, the effects of selenium (Se) and multiple applications of Se and biochar on rice MeHg bioaccumulation were investigated using pot and microcosm experiments. We report that Se amendment was still effective in reducing MeHg levels in paddy soil and rice grain after three years of aging. Biochar amendment (0.5% w/w) further decreased grain (brown rice) MeHg levels by 82-87%. The grain MeHg level decrease following the combination of Se and biochar amendment could be partly attributed to inhibition of net MeHg production in soil by Se. In addition, biochar decreased not only net MeHg production but also MeHg bioavailability in the soil, which could be due to organosulfur compounds in the biochar. Our findings suggest that multiple applications of Se and biochar could be a novel remediation strategy to mitigate MeHg accumulation in rice.

[前沿资讯] 新方法可大幅降低基因组基因型鉴定成本 进入全文

中国农业科学院

近日,中国农业科学院深圳农业基因组研究所开发了新的重测序文库制备方法——“AIO-seq”。该方法简化了文库制备的流程,极大地降低了文库制备的成本,为高通量全基因组重测序在育种中应用扫除了高成本障碍。相关研究成果在线发表在《植物-方法(Plant Methods)》上。据常玉晓研究员介绍,全基因组基因型鉴定在育种中具有重要的作用。虽然目前基于二代测序的全基因组基因型鉴定在技术层面已经非常成熟,但是其高昂的价格限制了在育种中的广泛应用。育种家普遍期望单个样本的全基因组基因型鉴定的价格能够降低至10美元左右。围绕这一技术难题,该课题组优化了常规的重测序文库制备方法,将传统方法文库扩增后的文库分选和定量这2个步骤,从“每个样品单独操作”的繁琐流程,优化为“多个样品混合操作”的简化流程。通过简化,可以实现一百多份样品混在一起只进行一次文库的分选和定量,大大降低了重测序文库的建库时间成本和试剂成本。此外,该方法还结合质量越来越好的国产建库试剂,进一步降低了试剂成本。最终应用新方法AIO-seq,可以将全基因组基因型鉴定的成本降低到育种家期望的10美元,为NGS在育种中的广泛应用扫除了障碍。

[前沿资讯] 科研创新进展:建立基因组编辑外源成分检测平台 进入全文

中国水稻信息网

近日,中国水稻研究所王克剑团队和中国科学院遗传与发育生物学研究所李家洋团队合作,在Science China Life Sciences在线发表了题为FED: a web tool for Foreign Element Detection of genome-edited organism的研究论文。该研究报道了一种对外源成分进行精确分析的工具FED(Foreign Element Detector,外源成分探测器)。基因组编辑技术为动植物遗传改良提供了革命性的遗传操作工具。但是,在基因组编辑过程中,通常需要将外源载体导入生物体细胞内,编辑完成后,再筛选出不含外源成分的个体。目前,美国、日本、加拿大、澳大利亚、巴西、阿根廷等多个国家已先后出台基因组编辑产品安全管理政策,其中确保没有外源成分是各国基因组编辑产品大规模商业化生产和市场准入的重要前提。目前,外源成分检测主要采用PCR等分子检测手段。但是,基于PCR的检测方法需要已知外源片段序列才能设计扩增引物,一次只能对少数几个完整的外源成分进行检测。而在外源片段序列未知或在体内出现变异等情况下,基于PCR的方法将无法对其进行有效检测,导致漏检。另外,基于PCR的检测方法易受实验条件的影响,导致假阳性或假阴性情况的发生。因此急需要发展一种高效灵敏的外源成分检测方法,保障基因编辑产品的安全。不同于传统的PCR检测,FED对全基因组重测序数据进行分析,可在外源成分信息未知的情况下,一次性完成对46695种不同外源成分序列的检测,同时FED还可以鉴定出外源成分的片段长度及在基因组上的精确插入位置。目前,FED已经内置了24种植物(水稻、小麦、玉米、大豆、油菜、西红柿等)和13种动物(猪、牛、羊、鸡、鸭等)的参考基因组信息,有望为全球基因组编辑生物的应用和安全监管提供重要工具平台。

[前沿资讯] 水稻DNA双链断裂修复基因克隆成功 进入全文

科学网

近日,《植物生理学》在线发表扬州大学农学院教授于恒秀团队在水稻中成功克隆的与DNA双链断裂(DSB)修复有关的基因OsATM。该研究详细解析了OsATM在水稻减数分裂过程中的作用,为进一步探析水稻育性分子机制提供了理论依据。论文作者于恒秀介绍,DNA作为遗传物质,保持其分子结构的完整性和稳定性对于细胞的存活和正常生理功能的发挥具有重要意义。在动植物日常生长环境中,包括电离辐射、细胞代谢产物在内的多种外源和内源性因素都能引起不同形式DNA损伤。其中DNA双链断裂是最严重的损伤形式,严重威胁到了细胞的正常生命活动。ATM蛋白作为DNA损伤的感知分子,在DNA双链断裂的修复过程中起到了核心作用。然而,哺乳动物atm突变体的性母细胞发生减数分裂停滞及凋亡,因此无法全面解析ATM蛋白在减数分裂过程中的作用。植物减数分裂缺少这种损伤修复的检验点机制,因此是研究相关蛋白的理想体系。早在2003年,拟南芥中的研究已证明,AtATM在减数分裂过程中具有重要作用,但其与减数分裂同源重组的关系一直未获解析。于恒秀团队通过图位克隆,从不育突变体中分离得到了三个OsATM的等位突变体。Osatm花粉母细胞中出现非同源染色体的异常黏连及染色体碎片。团队通过荧光原位杂交及免疫定位分析证明,突变体中同源染色体的配对及联会正常。OsDMC1是减数分裂同源搜索的关键蛋白,该蛋白的功能缺失会造成同源染色体无法联会,表现出单价体的表型。团队研究发现在Osdmc1 Osatm双突变体中,同源染色体无法联会,但染色体之间仍然存在严重的黏连及大量染色体碎片。这表明,Osatm减数分裂染色体的异常不依赖于同源重组过程,OsATM可能在平行于同源重组的DNA双链断裂修复途径中起作用。在体细胞产生DNA双链断裂损伤后,损伤位点附件的组蛋白H2AX会迅速被ATM磷酸化(称为γ-H2AX),以启动损伤响应。因此,用DNA双链断裂损伤诱导试剂博来霉素处理水稻根尖后,野生型细胞能观察到大量γ-H2AX信号,而Osatm中几乎观察不到该信号。研究人员进一步观察发现,在Osatm花粉母细胞中依然能观察到γ-H2AX信号,且信号点数目与野生型无显著差异。这一结果表明,水稻体细胞与生殖细胞H2AX的磷酸化可能存在机制上的差异。

[学术文献] Paclobutrazol Application Improves Grain 2AP Content of Thai Jasmine Rice KDML105 under Low-Salinity Conditions 进入全文

Journal of crop science and Biotechnology

KDML105 rice ( Oryza sativa L.) cultivar, also known as the jasmine rice, is the most valuable fragrant rice of Thailand. The aroma is attributed to a highly 2-acetyl-1-pyrroline (2AP) compound, which is abundantly produced when rice plants are cultivated in the infertile saline soil in northeastern Thailand. The area suitable for production of KDML105 has been limited, and the farmers suffer low grain yield as a trade-off for the premium quality. In this study, we investigated whether foliar application of paclobutrazol (PBZ), which is a plant growth retardant, could mimic the effect of salt stress in promoting the 2AP content of the Thai fragrant rice. PBZ was sprayed on KDML105 rice leaves during the vegetative or reproductive growth stages. PBZ application up to 150 ppm during the vegetative stage was found to have mild effects on growth performances and yield components compared to the reproductive stage. The 100 ppm PBZ foliar spray during the vegetative stage was also found to increase the levels of 2AP and proline, which might be directed toward the 2AP production, in KDML105 rice grains to nearly the levels found in rice cultivated under 0.4% NaCl. The effects of PBZ were found on other tested aromatic verities: PT1 and RD43, and a non-aromatic variety: RD31. However, the amylose content of RD31 was significantly reduced in response to the PBZ application. These results showed that PBZ application is a promising strategy for improving grain quality of fragrant rice, although the effects may vary among rice genetic backgrounds.

[学术文献] Nutritional status and risks of potentially toxic elements in some paddy soils and rice tissues 进入全文

International Journal of Phytoremediation

This experiment was conducted to investigate the potential risk of toxic elements in paddy soils and rice straws, bran, and husked grains in Kuchesfahan, Gilan, Iran. The average content of total and DTPA-extractable of Cd, Cu, Fe, Mn, Ni, Pb, and Zn were 7.0, 26.3, 20728.8, 1516.7, 43.8, 16.6, and 211.8 mg kg(-1), and 0.32, 14.1, 97.3, 63.4, 1.7, 4.8, and 56.2 mg kg(-1), respectively. In addition, the average content of Cd, Cu, Fe, Mn, Ni, Pb, and Zn in rice grain was 0.16, 2.4, 135.5, 34.1, 2.0, 0.6, and 15.0 mg kg(-1), respectively. The average transfer factor for Cd, Cu, Fe, Mn, Ni, Pb, and Zn from soil to straw was 0.38, 0.16, 0.004, 0.13, 0.3, 0.04, and 0.09, respectively. The average values of estimated daily intake for Cd, Cu, Fe, Mn, Ni, Pb, and Zn through rice consumption for adult are respectively, estimated to be 0.0004, 0.005, 0.32, 0.08, 0.005, 0.0015, and 0.035 mg kg(-1) body weight per day. There was no health risk index (HRI) values for adult greater than 1 (except three samples for Fe, and one sample for Mn and Cd); indicated that intake of single metal through the consumption of rice was safe. The average of heath index (HI) value for rice consumption was 0.33 and 0.35 for adult and children, respectively. Therefore, combination of several potentially toxic elements may not cause risk to local residents. Spatial distributions of HRI were obtained for potentially toxic metals in husked grains.

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