植物转基因沉默及控制

植物基因工程的目的就是获取外源基因能够按照设计要求正常表达和稳定遗传的转基因植物。近几年来,广泛报道了转基因植物中存在转基因沉默现象。主要阐述了两种转基因沉默的机理即转录水平的基因沉默和转录后水平的基因沉默,各种机理都涉及DNA DNA,DNA RNA,RNA RNA的相互作用。同时,还讨论一些控制转基因沉默现象的策略,特别是MAR在转基因植物中具有增强基因表达和减少株间差异的作用。     

植物组织培养中的内生细菌污染问题

植物组织中普遍存在内生菌,当植物组织进行离体培养时,这些内生菌就会产生污染。对内生菌污染概念进行了界定,对内生菌污染的种类、普遍性、症状与危害性作了阐述,综合了有关防治方法,并讨论了抗生素使用的效果、稳定性和应注意的问题。     

半干旱区人工林草地土壤旱化与土壤水分植被承载力

近年来在黄土高原地区多年生林草地。出现了以土壤旱化为主要特征的土壤退化现象。退化土壤反过来影响植物的生长和发育,最终将导致植物群落衰败和生态系统的退化,从而影响到林草植被的长期稳定,经济效益和生态效益的持续稳定发挥,这已成为当前林草植被建设的重大问题之一。分析了土壤旱化现象与土壤干层的关系,探讨了土壤干层的划分标准。认为防止土壤旱化的主要措施就是控制林草地密度和生产力,而控制林草地密度和生产力的理论依据就是土地植被承载力。在黄土高原大部分地区植物吸收和利用的土壤水分主要依靠当地的天然降水。土壤水分是限制植物生长的决定因子,该类地区土地植被承载力实质上为土壤水分的植被承载力。作者定义土壤水分植被承载力为土壤水分承载植物的最大负荷。它是指在较长时期内,在现有的条件下,当植物根系可吸收和利用土层范围内土壤水分消耗量等于或小于土壤水分补给量时,所能维持特定植物群落健康生长的最大密度。探讨了土壤水分植被承载力的确定方法和影响因素,认为凡是影响林草地土壤水分的补给和消耗,植物群落生长发育和植物水分利用效率的因素,包括地理位置、地形、气候、植被类型及其发育阶段,抚育管理措施都影响土壤水分植被承载力数值。开展土壤水分植被承载力研究对于林草地合理经营与管理具有重要意义。     

中国灭螺技术的研究进展

本文就我国在化学药物灭螺、环境改造灭螺、利用食螺动物和靶螺竞争生物灭螺及植物灭螺的研究进展进行了综述,以期为灭螺技术的开发和应用提供依据.     

Pan-tropical distribution of the Jurassic ostreid bivalves

Globally, the Jurassic cemented ostreid bivalves from northern Tibet, SW China, have a pan-tropical distribution pattern between palaeolatitudes of 60° South and North. Ostreid bivalves have tiny to large larvae, and nearly all of them have a cemented mode of life during their adult stage. The distribution pattern and the habits of the Jurassic ostreid bivalves revealed that, in the Jurassic time interval, all seas and oceans were interconnected, and ostreid bivalves were very capable of dispersion through their planktonic larval stage or as pseudoplankton during the post-larval stage, and even were able to cross the palaeo-Pacific Ocean from east to west. However, latitudinal temperature variation limited the distribution of these thermophilous bivalves to the lower and middle latitudes.     

Remote controlling of CAR-T cells and toxicity management: Molecular switches and next generation CARs

Cell-based immunotherapies have been selected for the front-line cancer treatment approaches. Among them, CAR-T cells have shown extraordinary effects in hematologic diseases including chemotherapy-resistant acute lymphoblastic leukemia (ALL), chronic lymphocytic leukemia (CLL), and non-Hodgkin lymphoma (NHL). In this approach, autologous T cells isolated from the patient''s body genetically engineered to express a tumor specific synthetic receptor against a tumor antigen, then these cells expanded ex vivo and re-infusion back to the patient body. Recently, significant clinical response and high rates of complete remission of CAR T cell therapy in B-cell malignancies led to the approval of Kymriah and Yescarta (CD19-directed CAR-T cells) were by FDA for treatment of acute lymphoblastic leukemia and diffuse large B-cell lymphoma. Despite promising therapeutic outcomes, CAR T cells also can elicit the immune-pathologic effects, such as Cytokine Release Syndrome (CRS), Tumor Lysis Syndrome (TLS), and on-target off-tumor toxicity, that hampered its application. Ineffective control of these highly potent synthetic cells causes discussed potentially life-threatening toxicities, so researchers have developed several mechanisms to remote control CAR T cells. In this paper, we briefly review the introduced toxicities of CAR-T cells, then describe currently existing control approaches and review their procedure, pros, and cons.     

The cost of being “real”: black authenticity,colourism, and Billboard Rap Chart rankings

Research on black authenticity identifies “oppressive othering” and “white standards of beauty”, particularly lighter skin tone, as key components. Few studies disentangle which of these two theoretical components matter the most for a particular outcome. Rap music, whose lyrics are often categorized as authentic expressions of blackness, offers an intriguing case to compare the effects of “oppressive othering” (as alcohol and drug lyrics) and “white standards of beauty” (as the rap artist’s skin tone) on national music charts. Analysing artists’ skin tone and lyrical content of songs ranked on Billboard Rap Year-End Charts from 2007 to 2011, results show that lighter skin tone is significantly and positively related to higher chart rankings. Alcohol and drug lyrics, however, had a non-significant effect. Implications are discussed in relation to the effects of the commodified imagery of “authentic” blackness in the new digital era of music.