Generation and Characterization of a Nanobody Against SARS-CoV

Virologica Sinica - The sudden emergence of severe acute respiratory syndrome coronavirus (SARS-CoV) has caused global panic in 2003, and the risk of SARS-CoV outbreak still exists. However, no...     

广西麻鸡FOXL2基因的克隆、序列分析及在高低产蛋量卵巢中的表达

为了研究鸡FOXL2基因的结构和功能,本研究克隆了广西麻鸡FOXL2基因编码区序列,分析了其突变位点及与其他物种的同源性和进化距离,以及在高产组和低产组母鸡卵巢组织中的表达水平.结果 表明:广西麻鸡FOXL2基因的编码区长度为918 bp,共编码305个氨基酸,存在一处错义突变和两处同义突变.通过物种间的同源性分析显示,广西麻鸡FOXL2基因与原鸡(Gallus gallus)、雉鸡(Phasianus colchicus)、绿头鸭(Anas platyrhynchos)、野鸽(Columba livia)、人(Homo sapiens)、小鼠(Mus musculus)的同源性分别为99.7％、98.8％、95.1％、92.0％、75.7％、75.5％.通过种间进化树分析表明,广西麻鸡与原鸡(Gallus gallus)的亲缘关系最近,与小鼠(Mus musculus)的亲缘关系最远.FOXL2在高低产蛋量鸡卵巢中的表达水平结果显示:FOXL2基因在高产蛋组中的表达量显著高于低产蛋组中的表达量(P＜0.05).该研究结果提示鸡FOXL2的序列相对较保守,对卵巢功能的维持和提高产蛋量具有功能性作用.     

高通量转录组RNA-seq研究成年牛下丘脑-垂体-卵巢

肉牛的性成熟受下丘脑-垂体-卵巢(HPO)轴的调节,但其具体作用机制尚不清楚.为了探讨HPO轴繁殖相关基因和调控机制,采用高通量转录组RNA-seq技术,研究了成年安格斯牛(30个月大)的下丘脑、垂体和卵巢.结果表明,HPO共有18 179个基因在GO(基因本体论)中注释,37 158个基因在KEGG(京都基因百科全书和基因组)中注释,36 645个基因在KOG(KEGG同源数据库)中注释.GO分析表明,HPO富集了8种生殖相关功能,主要是受精、单个组织生殖过程、子宫胚胎发育和雌激素反应.KEGG分析发现,HPO富集300条信号通路(SP),主要是癌症SP和磷脂酰肌醇3激酶蛋白激酶(PI3K-Akt)SP.与生殖有关的SPs共有16条,主要是Notch SP、神经营养素SP、哺乳动物雷帕霉素(mTOR)SP和血管内皮生长因子(VEG F)SP.为今后肉牛繁殖性能的提高、分子育种和同行参考提供了科学依据.     

Ovule morphogenesis and structure in Menispermaceae,focusing on the development of the single fertile ovule and its systematic significance

Menispermaceae is one of the core groups of Ranunculales. The single fertile ovule in each ovary in Menispermaceae varies greatly in integument number, micropyle formation, and integument lobe. However, data regarding ovule morphogenesis in the family are very limited. In this study, we document ovule development of selected species in the Menispermaceae using scanning electron microscopy and light microscopy. Ovule development in Menispermaceae shows the following characteristics. Two ovules are initiated in a young carpel, one of them degenerates gradually and the other develops into a fertile ovule in subsequent stages. Bitegmic in Sinomenium Diels. and Cocculus DC. and unitegmic in Stephania Lour. The formation of unitegmy is probably due to integumentary shifting. The annularly initiated inner integument is of dermal origin and has 2–3 cell layers in the family, but the semi-annularly initiated outer integument is of both dermal and subdermal origin. Both inner and outer integument are cup-shaped at maturity. The cup-shaped outer integument is formed due to the outer integument's extension to the concave (adaxial) side of the funiculus. The obturator is well developed and consists of 2–3 cell layers in Cocculus or 9–11 cell layers in Stephania. Ovule development of Menispermaceae suggests some common characteristics between Cocculus and Sinomenium, and derived unitegmy supports molecular data that indicate Stephania is one of the late-diverging lineages in the family. Integument lobations are present. The sterile ovule shows variations in the degeneration process. These results will provide evidence for exploring the evolution of ovules in Ranunculales.     

Evolution and diversity of axon guidance Robo receptor family genes

The diversity of axon guidance (AG) receptors reflects gains in complexity of the animal nervous system during evolution. Members of the Roundabout (Robo) family of receptors interact with Slit proteins and play important roles in many developmental processes, including AG and neural crest cell migration. There are four members of the Robo gene family. However, the evolutionary history of Robo family genes remain obscure. We analyzed the distribution of Robo family members in metazoan species ranging in complexity from hydras to humans. We undertook a phylogenetic analysis in metazoans, synteny analysis, and ancestral chromosome mapping in vertebrates, and detected selection pressure and functional divergence among four mammalian Robo paralogs. Based on our analysis, we proposed that the ancestral Robo gene could have undergone a tandem duplication in the vertebrate ancestor; then one round of whole genome duplication events occurred before the divergence of ancestral lamprey and gnathostome, generating four paralogs in early vertebrates. Robo4 paralog underwent segmental loss in the following evolutionary process. Our results showed that Robo3 paralog is under more powerful purifying selection pressure compared with other three paralogs, which could correlate with its unique expression pattern and function. Furthermore, we found four sites under positive selection pressure on the Ig1‐2 domains of Robo4 that might interfere with its binding to Slits ligand. Diverge analysis at the amino acid level showed that Robo4 paralog have relatively greater functional diversifications than other Robo paralogs. This coincides with the fact that Robo4 predominantly functions in vascular endothelial cells but not the nervous system.     

鳖甲煎丸通过LncRNA-mRNA顺式调控抑制肝癌细胞

为了研究鳖甲煎丸抑制肝癌细胞过程中lncRNA表达谱的变化及lncRNA-mRNA顺式调控在其中的机制,本研究通过CCK8方法检测鳖甲煎丸作用于SMMC-7721细胞后的增殖活性变化,经全细胞转录组学分析lncRNA的表达和特征后构建LncRNA-mRNA顺式调控网络.结果表明鳖甲煎丸含药血清作用肝癌细胞株后其增殖活性受到抑制.全细胞转录组学分析找到差异表达的172个LncRNA.构建lncRNA-mRNA顺式调控网络,对调控基因进行生存分析发现,SCRN1、PLEKHA1、HNRNPM、TMEM107、ETNK1、ISG20L2的表达与肝细胞癌患者生存率显著负相关(P＜0.05).因此得出结论,LncRNA参与鳖甲煎丸抑制肝癌细胞增殖的过程,LncRNA-mRNA顺式调控是其分子机制之一.     

桑黄Zn(II)2Cys6锌簇蛋白转录因子及其在不同碳氮源条件下的表达

Zn(II)2Cys6锌簇蛋白转录因子（C6 zinc）在真菌次生代谢产物合成中发挥重要作用。本研究首先利用本地BLAST,从桑黄Sanghuangporus sanghuang全基因组中获得Zn(II)2Cys6锌簇蛋白转录因子编码基因,并利用生物信息学手段分析编码蛋白保守结构域、一级结构及二级结构,构建蛋白系统发育树,最后利用半定量PCR对它们在不同碳源和氮源培养条件下的表达情况进行检测。结果显示:从桑黄基因组中分析获得的11个Zn(II)2Cys6锌簇蛋白均具有Cy6型锌指基序,属于GAL4型锌簇蛋白转录因子;它们均为不稳定亲水性蛋白,具磷酸化修饰位点,糖基化修饰位点较少或没有,定位于细胞核中;其二级结构主要以无规卷曲和α螺旋为主;系统发育树分析结果显示,桑黄Zn(II)2Cys6锌簇蛋白分为2个大分支,其中Ⅰ类分支转录因子的保守结构域分布于蛋白N-端,Ⅱ类分支转录因子的保守结构域则分布于蛋白C-端;11个桑黄Zn(II)2Cys6锌簇蛋白转录因子在不同培养基培养的菌丝体中呈现差异化表达,其中,肌醇培养基和乳糖培养基能够有效促进大部分锌簇蛋白转录因子的表达;另外,基因簇分析显示桑黄锌簇蛋白SHCZ4可能是NRPS-PKS杂合基因簇体系的途经特异性转录因子。该结果将为桑黄次生代谢产物合成调控相关转录因子的研究以及潜在次生代谢相关基因簇的挖掘提供参考依据。     

Drought stress and plant ecotype drive microbiome recruitment in switchgrass rhizosheath

The rhizosheath, a layer of soil grains that adheres firmly to roots, is beneficial for plant growth and adaptation to drought environments. Switchgrass is a perennial C4 grass which can form contact rhizosheath under drought conditions. In this study, we characterized the microbiomes of four different rhizocompartments of two switchgrass ecotypes (Alamo and Kanlow) grown under drought or well-watered conditions via 16S ribosomal RNA amplicon sequencing. These four rhizocompartments, the bulk soil, rhizosheath soil, rhizoplane, and root endosphere, harbored both distinct and overlapping microbial communities. The root compartments (rhizoplane and root endosphere) displayed low-complexity communities dominated by Proteobacteria and Firmicutes. Compared to bulk soil, Cyanobacteria and Bacteroidetes were selectively enriched, while Proteobacteria and Firmicutes were selectively depleted, in rhizosheath soil. Taxa from Proteobacteria or Firmicutes were specifically selected in Alamo or Kanlow rhizosheath soil. Following drought stress, Citrobacter and Acinetobacter were further enriched in rhizosheath soil, suggesting that rhizosheath microbiome assembly is driven by drought stress. Additionally, the ecotype-specific recruitment of rhizosheath microbiome reveals their differences in drought stress responses. Collectively, these results shed light on rhizosheath microbiome recruitment in switchgrass and lay the foundation for the improvement of drought tolerance in switchgrass by regulating the rhizosheath microbiome.     

The ScCas9++ variant expands the CRISPR toolbox for genome editing in plants

The development of clustered regularly interspaced palindromic repeats (CRISPR)-associated protein (Cas) variants with a broader recognition scope is critical for further improvement of CRISPR/Cas systems. The original Cas9 protein from Streptococcus canis (ScCas9) can recognize simple NNG-protospacer adjacent motif (PAM) targets, and therefore possesses a broader range relative to current CRISPR/Cas systems, but its editing efficiency is low in plants. Evolved ScCas9⁺ and ScCas9⁺⁺ variants have been shown to possess higher editing efficiencies in human cells, but their activities in plants are currently unknown. Here, we utilized codon-optimized ScCas9, ScCas9⁺ and ScCas9⁺⁺ and a nickase variant ScCas9n⁺⁺ to systematically investigate genome cleavage activity and cytidine base editing efficiency in rice (Oryza sativa L.). This analysis revealed that ScCas9⁺⁺ has higher editing efficiency than ScCas9 and ScCas9⁺ in rice. Furthermore, we fused the evolved cytidine deaminase PmCDA1 with ScCas9n⁺⁺ to generate a new evoBE4max-type cytidine base editor, termed PevoCDA1-ScCas9n⁺⁺. This base editor achieved stable and efficient multiplex-site base editing at NNG-PAM sites with wider editing windows (C₋₁–C₁₇) and without target sequence context preference. Multiplex-site base editing of the rice genes OsWx (three targets) and OsEui1 (two targets) achieved simultaneous editing and produced new rice germplasm. Taken together, these results demonstrate that ScCas9⁺⁺ represents a crucial new tool for improving plant editing.