Flexible chromosome painting based on multiplex PCR of oligonucleotides and its application for comparative chromosome analyses in Cucumis

Chromosome painting is a powerful technique for chromosome and genome studies. We developed a flexible chromosome painting technique based on multiplex PCR of a synthetic oligonucleotide (oligo) library in cucumber (Cucumis sativus L., 2n = 14). Each oligo in the library was associated with a universal as well as nested specific primers for amplification, which allow the generation of different probes from the same oligo library. We were also able to generate double‐stranded labelled oligos, which produced much stronger signals than single‐stranded labelled oligos, by amplification using fluorophore‐conjugated primer pairs. Oligos covering cucumber chromosome 1 (Chr1) and chromosome 4 (Chr4) consisting of eight segments were synthesized in one library. Different oligo probes generated from the library painted the corresponding chromosomes/segments unambiguously, especially on pachytene chromosomes. This technique was then applied to study the homoeologous relationships among cucumber, C. hystrix and C. melo chromosomes based on cross‐species chromosome painting using Chr4 probes. We demonstrated that the probe was feasible to detect interspecies chromosome homoeologous relationships and chromosomal rearrangement events. Based on its advantages and great convenience, we anticipate that this flexible oligo‐painting technique has great potential for the studies of the structure, organization, and evolution of chromosomes in any species with a sequenced genome.     

The role of astrocytes in oxidative stress of central nervous system: A mixed blessing

Central nervous system (CNS) maintains a high level of metabolism, which leads to the generation of large amounts of free radicals, and it is also one of the most vulnerable organs to oxidative stress. Emerging evidences have shown that, as the key homeostatic cells in CNS, astrocytes are deeply involved in multiple aspects of CNS function including oxidative stress regulation. Besides, the redox level in CNS can in turn affect astrocytes in morphology and function. The complex and multiple roles of astrocytes indicate that their correct performance is crucial for the normal functioning of the CNS, and its dysfunction may result in the occurrence and progression of various neurological disorders. To date, the influence of astrocytes in CNS oxidative stress is rarely reviewed. Therefore, in this review we sum up the roles of astrocytes in redox regulation and the corresponding mechanisms under both normal and different pathological conditions.     

Mapping and characterization of major QTL for spike traits in common wheat

Physiology and Molecular Biology of Plants - The spike traits of wheat can directly affect yield. F2 and F2:3 lines derived from the cross of the multi-spikelet female 10-A and the uni-spikelet...     

蛹虫草菌生物合成虫草素的研究进展

蛹虫草Cordyceps militaris是我国传统的药用真菌,虫草素是蛹虫草的主要活性成分,具有抗癌、抗肿瘤、抗病毒等多种生理功能。蛹虫草菌液体发酵是最有希望实现高效生产虫草素的途径,但现阶段生产强度低,亟需应用发酵工程及代谢工程手段提高虫草素产量。文中对液体发酵体系中培养基组分(碳/氮源、前体物质、金属离子等)和培养条件(pH、溶氧量、光照等)对虫草素产量的影响进行了总结,并对虫草素的分离纯化、生物合成基因簇及合成代谢途径进行了阐述,最后探讨了实现虫草素高效生产的关键环节。     

温度诱导Targetron系统用于大肠杆菌高效基因失活

构建基于TeI3c/4c嗜热二型内含子的温度诱导Targetron基因失活系统 (Thermotargetron),并应用于中温微生物基因编辑。在大肠杆菌HMS174 (DE3) 基因组中,选择Subunit of flagellum基因 (fliC) 和C4 dicarboxylate orotate:H+ symporter基因 (dctA) 为靶基因。根据TeI3c/4c DNA识别规则,在fliC和dctA基因中选择fliC489a、fliC828s、fliC1038s和dctA2a位点为基因打靶位点。使用重叠延伸PCR方法,基于pHK-TT1A质粒构建打靶载体。打靶载体转化HMS174菌株,对数期转化子培养液48 ℃热激1 h后涂布于氯霉素抗性LB平板上。使用菌落PCR和DNA测序检测突变株并计算基因失活效率。获得突变株后,通过琼脂穿刺和碳源代谢实验,鉴定ΔfliC、ΔdctA突变株表型变化。菌落PCR测序结果表明,TeI3c/4c插入到fliC和dctA基因设计位点,且打靶效率高达100%。突变株表型验证实验表明,ΔfliC突变株运动能力显著下降,ΔdctA突变株苹果酸代谢能力缺失。综上所述,文中建立了一套适用于嗜中温微生物的温度诱导型、高效基因失活系统,该系统可通过控制宿主菌在48 ℃保温时间实现高效、靶向、精准基因失活。     

中国苦苣苔科植物新资料——小花线柱苣苔

该文报道了产自中国西藏自治区墨脱县境内的线柱苣苔属(Rhynchotechum Blume)中国分布新记录——小花线柱苣苔(R. parviflorum Blume)。该新记录种常生长在林中溪流附近的崖壁以及次生林下阴湿生境中,主要辨别特征为叶基本对生,花萼裂片被绢毛,花梗被黄褐色绒毛,花冠筒较小,子房具短柔毛,果无毛至微柔毛。印度学者于2020年记载为印度新分布,而原始文献中记录的凭证标本采集点位于中国西藏自治区墨脱县境内,故对原文记述的产地信息提出质疑。同时,在前人的研究中部分馆藏的线柱苣苔属植物标本被认定为该新记录种,在此一并提出该新记录种在中国的分布地理信息和详细描述。     

自然越冬期软枣猕猴桃枝条组织结构及内源激素的变化特征

该试验以抗寒性不同的5年生软枣猕猴桃品种‘魁绿’、‘丰绿’和‘96-6’为试验材料,测定分析自然越冬期间枝条组织解剖结构、细胞膜透性和内源激素GA3、ABA、IAA含量水平的变化,以明确不同品种软枣猕猴桃越冬期间对低温的适应能力及其内在生理机制,为软枣猕猴桃抗寒品种的选育及鉴别提供理论依据。结果表明:(1)软枣猕猴桃枝条木质部比率大小依次为‘魁绿’>‘96-6’>‘丰绿’,皮层比率依次为‘丰绿’>96-6’>魁绿’,二者表现趋势相反,且‘魁绿’枝条的解剖结构与其他两品种差异显著。(2)在自然越冬期间,各品种软枣猕猴桃枝条相对电导率和MDA含量随温度变化均呈先升后降的趋势,在温度最低的1月份达到最高,其中‘魁绿’枝条的相对电导率和MDA含量变化幅度最小,而‘丰绿’受低温影响较大。(3)在11月份至2月份,随自然温度的变化,各品种软枣猕猴桃枝条的GA3和IAA含量均呈先降低后升高的变化趋势,ABA含量则呈先升后降的趋势,且都在1月份分别达到最低或最高值。研究发现,在自然越冬期间,低温对3个软枣猕猴桃品种的组织解剖结构、膜透性及内源激素含量均都造成较大的影响,品种‘魁绿’枝条的木质部比率最大、皮层比率最小,相对电导率和MDA含量变化幅度最小,内源激素含量GA3和ABA/GA3变化趋势较小,故其抗寒性比‘丰绿’和‘96-6’更强。