Embryo-mediated genome editing for accelerated genetic improvement of livestock

Selecting beneficial DNA variants is the main goal of animal breeding. However, this process is inherently inefficient because each animal only carries a fraction of all desirable variants. Genome editing technology with its ability to directly introduce beneficial sequence variants offers new opportunities to modernize animal breeding by overcoming this biological limitation and accelerating genetic gains. To realize rapid genetic gain, precise edits need to be introduced into genomically-selected embryos, which minimizes the genetic lag. However, embryo-mediated precision editing by homology-directed repair (HDR) mechanisms is currently an inefficient process that often produces mosaic embryos and greatly limits the numbers of available edited embryos. This review provides a summary of genome editing in bovine embryos and proposes an embryo-mediated accelerated breeding scheme that overcomes the present efficiency limitations of HDR editing in bovine embryos. It integrates embryo-based genomic selection with precise multi-editing and uses embryonic cloning with elite edited blastomeres or embryonic pluripotent stem cells to resolve mosaicism, enable multiplex editing and multiply rare elite genotypes. Such a breeding strategy would enable a more targeted, accelerated approach for livestock improvement that allows stacking of beneficial variants, even including novel traits from outside the breeding population, in the most recent elite genetic background, essentially within a single generation.     

天维菌素酰化衍生物的合成及杀虫杀螨活性

以天维菌素B、天维菌素B单糖苷和天维菌素B苷元为原料,经选择性C-5羟基保护,在C-13、C-4′和C-4″位引入不同酰基基团,合成了3个系列共23个天维菌素B酰化衍生物,并通过1H NMR、13C NMR和高分辨质谱对所有目标化合物的结构进行了表征。生物活性测定结果表明,所有衍生物对小菜蛾Plutella xylostella、朱砂叶螨Tetranychus cinnabarinus以及松材线虫Bursaphelenchus xylophilus均表现出不同程度的毒杀活性,其中天维菌素B C-4″位衍生物的活性优于C-4′位衍生物及13位衍生物。化合物8e对小菜蛾和松材线虫的毒杀活性最优,LC50值分别为9.2 mg/L和0.42 mg/L,化合物8b对朱砂叶螨的毒性最高,LC50值为0.0019 mg/L,均优于对照药天维菌素B。     

Down-regulation of miR-153-3p attenuates H2O2-induced H9C2 cell injury by promoting Nrf2 expression

AIM To study the effect of microRNA-153-3p (miR-153-3p) knock-down on oxidative injury of H9C2 cells induced by H₂O₂ and its specific mechanism. METHODS The oxidative stress injury of H9C2 cell model was induced by H₂O₂, and then the cell viability and the expression of miR-153-3p were detected by MTT assay and RT-qPCR, respectively. The effects of miR-153-3p knock-down on the H9C2 cell injury under oxidative stress were studied by RNA interference technology. The targets of miR-153-3p were identified by Western blot and dual-luciferase reporter assay. RESULTS MTT assay showed that the viability of H9C2 cells was decreased with the increase in H₂O₂ concentration (P<0.05). The results of RT-qPCR showed that the expression of miR-153-3p was increased with the increase in H₂O₂ concentration (P<0.05). Knock-down of miR-153-3p increased the viability of H9C2 cells under oxidative stress, decreased the cell apoptosis and the content of malondialdehyde (MDA), and increased the activity of superoxide dismutase (SOD). The expression of nuclear factor E2-related factor 2（Nrf2） and antioxidant response element（ARE） activity were increased with the increase in H₂O₂ concentration (P<0.01). TargetScan analysis and dual-luciferase reporter assay showed that Nrf2 was one of the potential target genes of miR-153-3p. The results of Western blot further showed that over-expression of miR-153-3p inhibited the expression of Nrf2 (P<0.01), while down-regulation of miR-153-3p increased the expression of Nrf2 (P<0.01). Dual interference with Nrf2 and miR-153-3p significantly reduced H9C2 cell viability, promoted the apoptosis, increased MDA content, and decreased SOD activity in the presence of H₂O₂ (P<0.01). CONCLUSION Inhibition of miR-153-3p expression attenuates the injury of H9C2 cells induced by H₂O₂ through up-regulating Nrf2/ARE signaling pathway.     

利用CRISPR/Cas9系统敲除葡萄中VviEDR2提高对白粉病的抗性

利用CRISPR/Cas9系统定点编辑葡萄白粉病感病基因VviEDR2（Enhanced disease resistance 2）,在VviEDR2的DUF1336结构域设计靶位点VviEDR2-T1,构建CRISPR/Cas9敲除载体,通过农杆菌介导法转化‘无核白’葡萄胚性愈伤组织。对PCR阳性植株进行靶位点扩增测序,结果表明,共有8个转基因植株在靶位点处发生不同类型的双等位基因突变,编辑效率为32%;突变体植株生长势较弱,叶片较小,茎秆丛生、细弱。进一步对突变体植株进行抗病检测,结果表明,接种葡萄白粉菌（Erysiphe necator Schw.）5 d后,突变体植株叶片上白粉菌孢子仅能萌发出少量较短初级菌丝,表皮细胞产生大量明显的H2O2,而野生型叶片中白粉菌萌发出大量初级菌丝、次级菌丝和吸器,无明显H2O2产生。这些结果表明,可以利用CRISPR/Cas9技术编辑葡萄感病基因VviEDR2,提高葡萄白粉菌抗性。     

黄瓜花叶病毒浙江白术分离物全基因组序列测定与分析

正白术(Atractylodes macrocephala Koidz.)为菊科(Compositae)苍术属(Atractylodes)多年生草本植物,其根茎入药具补脾健胃、燥湿利水、止汗安胎等功效,在我国广泛栽培,并以于术(浙江临安于潜)品质最佳[1]。近年来白术生产由于品种单一,长期连作等因素导致病毒病害日趋严重。据报道,黄瓜花叶病毒(Cucumber mosaic virus,CMV)~([2])、蚕豆萎蔫病毒2号(Broad bean wilt virus 2,     

宁麦9号与扬麦158株高及其构成因素的遗传解析

宁麦9号与扬麦158是我国长江中下游麦区的主栽品种和骨干亲本,长江中下游麦区近3年来审定品种中80%都是其衍生后代,研究其性状的遗传具重要意义。以宁麦9号与扬麦158为亲本构建的包含282个家系的重组自交系群体为材料,利用Illumina 90k芯片对群体进行基因型分析,建立高密度遗传图谱。连续3个生长季对株高及节间长度、穗长等株高构成因素进行测定,结合遗传图谱对株高及相关性状进行QTL定位,获得14个控制株高及其构成因素的稳定表达位点。通过进一步位置比对,聚焦到6个染色体区段,初步明确了各节间对株高的遗传调控机制。同时,将6个染色体区段中同源性较低的连锁标记转化为适用于高通量筛选的KASP标记,利用101份区域试验材料进行标记效应验证,结果显示聚合Qph-2D与Qph-5A.1两个位点具有较高的选择效率,继续聚合Q2A后,中选材料显著减少,可能降低选择效率;对Q2A与Q5A两个一因多效位点的选择建议以降低株高的等位变异为主;Qd1-5D可作为穗下节间(D1)的选择标记对株高展开优化选择。期望以上结果能为长江中下游麦区的小麦株高遗传改良提供帮助。     

11份玉米自交系单株产量等性状的配合力与遗传参数研究

旨在研究玉米自交系单株产量等性状的配合力、遗传力及反交效应,为玉米自交系的选育和杂交种的组配提供依据。以11份玉米自交系为试材,按Griffing Ⅲ完全双列杂交法组配110个组合,观测杂交种的单株产量、株高、穗位高、雄穗分支数、雄穗主轴长、抽丝期和开花期等7个性状的表型数据,并对上述性状的一般配合力、特殊配合力、广义遗传力、狭义遗传力和反交效应进行估算。供试材料除雄穗主轴长的特殊配合力差异不显著外,其余性状的一般配合力和特殊配合力差异均达到极显著水平。JZ3和JZ6两个自交系单株产量的一般配合力为极显著正值,两对组合JZ9×JZ2和JZ2×JZ9、JZ6×JZ3和JZ3×JZ6的单株产量具有最大的正向SCA效应值,分别为40.68 g和35.24 g。单株产量的反交效应差异极显著,部分自交系的反交效应方差较大。7个性状的广义遗传力从大到小依次为,雄穗分支数、株高、开花期、穗位高、抽丝期、单株产量和雄穗主轴长;狭义遗传力从大到小依次为,雄穗分支数、株高、穗位高、开花期、雄穗主轴长、抽丝期和单株产量。试验结果表明单株产量性状的显性遗传方差占比最大,狭义遗传力最小,易受环境条件的影响,对该性状的选择适宜在晚代进行;单株产量性状具有显著的反交效应,故部分自交系需严格控制正反交方式。