抑制Ligase4或Xrcc6活性增强斑马鱼原始生殖细胞中DNA同源重组的效率（英文）

利用斑马鱼作为体内模型,研究旨在提高斑马鱼原始生殖细胞(Primordial germ cells,PGCs)中同源重组(Homologous recombination,HR)的效率。首先,将UAS:m RFP-nos1载体显微注射到Tg(kop:Kal TA4)转基因胚胎中标记转基因PGCs,结果表明筛选PGCs特异表达m RFP的胚胎能够相对提高转基因的生殖系传递效率。随后建立了PGCs中HR效率的评估体系,并且证明抑制DNA ligase IV(Lig4)和Xrcc6(曾用名Ku70)的活性不但在全胚胎水平,而且在PGCs水平都能够显著提高HR的效率。研究表明Tg(kop:Kal TA4)转基因品系是开展HR介导的基因打靶的一个有效平台。     

Midkine-a通过限制心肌细胞总数的方式阻碍斑马鱼胚胎心脏生长

目的探讨一种可溶性的外分泌因子midkine-a在斑马鱼胚胎心脏发育过程中的功能。方法在整体胚胎上做midkine-a RNA的原位杂交实验;利用原有的转基因斑马鱼系Tg(pmidkine-a:EGFP),动态观察胚胎从出生到心脏发育成形这一段时间心脏荧光表达情况;将原有的转基因斑马鱼体系Tg(phsp:midkine-a:EGFP)胚胎进行热休克而过表达midkine-a,观察胚胎心脏表型;利用Tg(pcmlc2:dsRed)鱼系胚胎的心肌细胞核带有红色荧光,能进行单个心脏心肌细胞计数这一特点,将杂合的Tg(phsp:midkine-a:EGFP)鱼系与纯合的Tg(pcmlc2:dsRed)鱼系交配,以得到Tg(phsp:midkine-a:EGFP/pcmlc2:dsRed)的杂合胚胎,对其进行热休克而过表达midkinea,计算每个胚胎心脏内心肌细胞的总数;用吗啉寡聚核苷酸(morphonino,MO)阻碍新生胚胎内的midkine-a mRNA表达,观察胚胎心脏表型。结果原位杂交试验证实midkine-a在胚胎48 hpf(hour post fertilization,受精后,用来标记斑马鱼胚胎年龄)大时表达于心脏;转基因Tg(pmidkine-a:EGFP)胚胎在72 hpf时其EGFP表达于心脏;Tg(phsp:midkine-a:EGFP)胚胎在过表达midkine-a后心脏变小;吗啉寡聚核苷酸敲除midkine-a对胚胎心脏发育无影响;最后在Tg(phsp:midkine-a:EGFP/pcmlc2:dsRed)鱼系胚胎内过表达midkine-a导致其单个心脏内心肌细胞数目变少,与其小心脏外形吻合。结论 midkine-a在斑马鱼胚胎发育过程中表达于胚胎心脏;过表达midkine-a导致胚胎心脏内心肌细胞总数减少及心脏变小;敲除midkine-a则对胚胎心脏发育无影响。     

荧光转基因斑马鱼Tg(ttn.2:EGFP)的构建

为了建立一种用于研究肌肉和心脏发育及其相关疾病的绿色荧光蛋白(enhanced green fluorescent protein,EGFP)转基因斑马鱼品系,本研究使用斑马鱼ttn.2基因编码区上游启动子序列和绿色荧光蛋白基因编码序列构建了重组表达载体,并将该载体和Tol2转座酶的加帽mRNA显微共注射入斑马鱼1-细胞期胚胎,通过荧光检测、遗传杂交筛选和分子鉴定等方法,成功建立了能稳定遗传的Tg(ttn.2:EGFP)转基因斑马鱼品系。荧光表达分析及原位杂交分析结果表明,绿色荧光信号在斑马鱼肌肉和心脏组织中特异表达模式与ttn.2基因的mRNA表达一致。通过反向PCR鉴定转基因表达载体在F1代斑马鱼品系中的随机整合位点,结果表明:No.33转基因品系的EGFP基因整合在斑马鱼的4号和11号染色体上,No.34转基因品系则整合在1号染色体上。该荧光转基因斑马鱼品系Tg(ttn.2:EGFP)的成功构建为肌肉和心脏发育以及相关疾病研究提供了一个新的理想实验模型。此外,绿色荧光强烈表达的斑马鱼品系还可以作为一种新的观赏鱼。     

C型利钠肽基因调控斑马鱼胚胎血管发育

本研究旨在探索C型利钠肽前体蛋白基因(natriuretic peptide precursor C,nppc)在斑马鱼胚胎期的表达及其在血管发育过程中的功能。利用胚胎整体原位杂交技术检测nppc基因在斑马鱼胚胎期的表达。同时使用转基因斑马鱼系Tg(flk1:GFP)和Tg(fli1a:n GFP),显微注射nppc特异性吗啉基反义寡核苷酸(morpholino)和nppc m RNA调控nppc基因表达,利用激光共聚焦显微镜观察分析斑马鱼节间血管(intersegment vessel,ISV)表型,并统计内皮细胞数目。结果显示,在受精后24 h和48 h,nppc基因在斑马鱼脑、心脏、血管系统中都有表达。下调nppc基因表达导致ISV发育缺陷,ISV内皮细胞数目减少。以上结果表明下调nppc基因表达可能通过抑制内皮细胞增殖和内皮细胞迁移调控斑马鱼胚胎血管发育。     

斑马鱼胚胎胚盾特异表达基因的鉴定

目的由于原肠期细胞的剧烈运动,在斑马鱼胚胎的背侧汇聚形成了称为胚盾(shield organizer)的结构,是胚胎发育的信号组织中心,在背腹轴建立和胚层诱导过程中具有关键作用。系统鉴定在胚盾特异表达的基因,可为进一步探讨胚盾形成的机制及其指导胚胎早期发育的分子机理提供参考。方法 Tg(gsc:GFP)转基因鱼在胚盾表达特异的绿色荧光。通过流式细胞分选技术分离富集GFP阳性细胞并提取总RNA进行RNA深度测序,检测可能在胚盾高水平表达的基因。然后利用荧光实时定量PCR(quantitative real-time PCR,qRT-PCR)和原位杂交技术鉴定若干在胚盾特异表达的基因。结果从Tg(gsc:GFP)转基因鱼胚胎中分离富集到了纯度超过96%的GFP阳性细胞,RNA深度测序的结果显示有657个基因的表达水平比整胚细胞或GFP阴性细胞高2倍以上。最后,确认了KIAA1324、ripply1、twist2、isthmin1、nme4、zgc174153、rrbp1b等7个基因在胚盾特异表达。结论系统鉴定到了斑马鱼胚胎胚盾特异表达基因,为下一步研究这些基因的发育生物学功能奠定了基础。     

stat3通过促进轴突生长间接抑制间神经丘早熟

鱼类侧线系统由感受水流的机械感受器和传导信息的侧线神经组成.stat3在斑马鱼侧线神经丘和侧线神经节中特异性表达,但stat3在斑马鱼后侧线系统发育过程中的功能仍然不清楚.本研究利用CRISPR/Cas9在斑马鱼中成功敲除stat3基因.然后,利用Tg(SqET20:GFP)转基因鱼追踪后侧线神经丘的发育.从4 dpf...     

生长激素促进斑马鱼尾鳍的再生

目的建立生长激素过表达的转基因斑马鱼,研究生长激素在斑马鱼尾鳍再生过程中的作用。方法利用Gateway技术构建表达质粒"pDestTol2CG2; ubi:GH-polyA",在一细胞期显微注射表达质粒和转座酶mRNA后,通过荧光显微镜和qPCR技术筛选鉴定GH过表达的转基因斑马鱼。将斑马鱼分为对照组(野生型)和生长激素过表达组,尾鳍横切后,记录分析斑马鱼尾鳍再生过程。结果转基因斑马鱼中心脏被绿色荧光蛋白标记。荧光定量PCR检测结果显示GH表达水平显著高于对照组(P<0.05)。斑马鱼尾鳍横断后,生长激素过表达组的再生速度显著提高(P<0.05)。结论建立稳定生长激素过表达的转基因斑马鱼品系,过表达生长激素能够提高斑马鱼尾鳍再生速度。     

Non-muscle Myosin Ⅱ-A调节斑马鱼胚胎发育过程中肠内分泌细胞的极化

胃肠道上皮由包括肠内分泌细胞在内的多种细胞类型组成,其中肠内分泌细胞占胃肠道上皮细胞总量的1%左右。在哺乳动物胚胎发育过程中,肠内分泌细胞位于深层组织,因此很难观察和研究。到目前为止,参与调节肠内分泌细胞形成和更新的分子调控机制仍然很不清楚。Tg(nkx2.2a:m EGFP)转基因斑马鱼品系中GFP表达在发育过程中的肠内分泌细胞,并且在胚胎期斑马鱼通体透明,因此Tg(nkx2.2a:m EGFP)为研究胚胎发育过程中肠内分泌细胞的形成过程及其分子调控提供了良好的模型。该研究发现,斑马鱼肠内分泌细胞形成的关键阶段为受精后48~72 h(hour past fertilization,hpf),而极化的关键时期为60~72 hpf。斑马鱼中Non-muscle Myosin II-A(NM II-A)对应的两个基因myh9a和myh9b在肠内分泌细胞极化关键阶段的肠上皮表达。在60~70 hpf,利用不同浓度的NM II功能特异性的抑制剂blebbistatin处理Tg(nkx2.2a:m EGFP)斑马鱼胚胎,结果显示:blebbistatin可抑制肠内分泌细胞的极化,并呈现剂量依赖性,随着blebbistatin浓度的增加极化细胞的比例越来越低;提示NM II-A调节斑马鱼胚胎发育过程中肠内分泌细胞的极化。     

原生殖细胞与转基因家禽

鸟类的原生殖细胞来自于上胚层胚盘透明区的中央盘处,分离出的PGCs可以被转至受体胚中,可以获得由供体胚PGCs和受体胚PGCs组成的生殖系嵌合体。在这一过程中,如果将外源基因转入供体PGCs,受体胚后代则成为转基因鸟类。利用禽类PGCs作为转基因的载体,来生产嵌合体胚胎和子代为目前研究禽类转基因的一种较为理想的方法。     

Baff转基因斑马鱼的构建及相关基因表达检测

通过RT-PCR法由斑马鱼脾脏克隆B细胞刺激因子baff基因,构建过表达斑马鱼baff且携带有绿色荧光标记蛋白的重组质粒pIRES2-GFP-baff;胚胎显微注射获得转基因斑马鱼胚胎;通过GFP荧光标记跟踪并筛选转基因阳性鱼;Western blot法鉴定Baff-GFP融合蛋白表达情况;qPCR检测baff,GFP及baff下游相关基因bcl-2,il-4mR-NA表达情况。结果表明细胞、胚胎及幼鱼baff和GFP均高表达,baff下游基因bcl-2激活和il-4基因抑制表达。通过胚胎显微注射法可成功获得过表达baff的转基因斑马鱼,此研究为建立红斑狼疮转基因斑马鱼模型及高通量筛选Baff拮抗剂奠定了基础。     

Inducible Sterilization of Zebrafish by Disruption of Primordial Germ Cell Migration

During zebrafish development, a gradient of stromal-derived factor 1a (Sdf1a) provides the directional cue that guides the migration of the primordial germ cells (PGCs) to the gonadal tissue. Here we describe a method to produce large numbers of infertile fish by inducing ubiquitous expression of Sdf1a in zebrafish embryos resulting in disruption of the normal PGC migration pattern. A transgenic line of zebrafish, Tg(hsp70:sdf1a-nanos3, EGFP), was generated that expresses Sdf1a under the control of the heat-shock protein 70 (hsp70) promoter and nanos3 3?UTR. To better visualize the PGCs, the Tg(hsp70:sdf1a-nanos3, EGFP) fish were crossed with another transgenic line, Tg(kop:DsRed-nanos3), that expresses DsRed driven by the PGC-specific kop promoter. Heat treatment of the transgenic embryos caused an induction of Sdf1a expression throughout the embryo resulting in the disruption of their normal migration. Optimal embryo survival and disruption of PGC migration was achieved when transgenic embryos at the 4- to 8-cell stage were incubated at 34.5°C for 18 hours. Under these conditions, disruption of PGC migration was observed in 100% of the embryos. Sixty-four adult fish were developed from three separate batches of heat-treated embryos and all were found to be infertile males. When each male was paired with a wild-type female, only unfertilized eggs were produced and histological examination revealed that each of the adult male fish possessed severely under-developed gonads that lacked gametes. The results demonstrate that inducible Sdf1a expression is an efficient and reliable strategy to produce infertile fish. This approach makes it convenient to generate large numbers of infertile adult fish while also providing the capability to maintain a fertile brood stock.     

Isolation of teleost primordial germ cells using flow cytometry

Primordial germ cells (PGCs) generate gametes, the only cells that can transmit genetic information to the next generation. A previous report demonstrated that a fusion construct of green fluorescent protein (gfp) and zebrafish nos 1 3UTR mRNA could be used to label PGCs in a number of fish species. Here, we sought to exploit this labeling strategy to isolate teleost PGCs by flow cytometry (FCM), and to use these isolated PGCs to examine germ cell migration to the gonadal region. In zebrafish, medaka and goldfish, the PGCs were labeled by injecting the gfp-nos1 3UTR mRNA into 1- 4 cell embryos. When the embryos had developed to the somitogenesis or later stages, they were enzymatically disaggregated and GFP positive cells isolated using FCM. PGCs in the different species clustered in the same segments of the FCM scatter diagrams for total embryonic cells produced by plotting the forward scatter intensity against GFP intensity. In situ hybridization showed that the sorted zebrafish cells expressed vasa RNA in their cytoplasm, suggesting that they were PGCs. When the migration ability of the sorted cells from zebrafish was examined in an in vivo transplantation experiment, approximately 30% moved to the gonadal region of host embryos. These observations demonstrate that PGCs can be isolated without use of transgenic fishes and that the isolated PGCs retain the ability to migrate. Our data indicate that this technique will be of value for isolating PGCs from a range of fish species.     

Inter-species transplantation and migration of primordial germ cells in cyprinid fish

Primordial germ cells (PGCs) are the only cells in developing embryos that can transmit genetic information to the next generation. PGCs therefore have considerable potential value for gene banking and cryopreservation, particularly via production of donor gametes using germ-line chimeras. In some animal species, including teleost fish, the feasibility of using PGC transplantation to obtain donor-derived offspring, within and between species, has been demonstrated. Successful use of PGC transplantation to produce germ-line chimeras is absolutely dependent on the migration of the transplanted cells from the site of transplantation to the host gonadal region. Here, we induced germ-line chimeras between teleost species using two different protocols: blastomere transplantation and single PGC transplantation. We evaluated the methods using the rate of successful migration of transplanted PGCs to the gonadal region of the host embryo. First, we transplanted blastomeres from zebrafish, pearl danio, goldfish, or loach into blastula-stage zebrafish embryos. Some somatic cells, derived from donor blastomeres, were co-transplanted with the PGCs and formed aggregates in the host embryos; a low efficiency of PGC transfer was achieved. Second, a single PGC from the donor species was transplanted into a zebrafish embryo. In all inter-species combinations, the donor PGC migrated toward the gonadal region of the host embryo at a comparatively high rate, regardless of the phylogenetic relationship of the donor and host species. These transplantation experiments showed that the mechanism of PGC migration is highly conserved beyond the family barrier in fish and that transplantation of a single PGC is an efficient method for producing inter-species germ-line chimeras.     

Visualization of primordial germ cells in vivo using GFP-nos1 3'UTR mRNA

In some teleost fish, primordial germ cells (PGCs) inherit specific maternal cytoplasmic factors such as vasa and nanos 1 (nos1) mRNA. It has been shown that the 3'untranslated regions (UTRs) of vasa and nos1 have critical roles for stabilization of these RNAs in zebrafish PGCs. In this study, to determine whether this role of the nos 1 3'UTR is conserved between teleost species, we injected artificially synthesized mRNA, combining green fluorescent protein (GFP) and the zebrafish nos 1 3'UTR (GFP-nos 1 3'UTR mRNA), into the fertilized eggs of various fish species. The 3'UTR of the Oryzias latipes vasa homologue (olvas ) mRNA was assayed in the same manner. We demonstrate that the PGCs of seven teleost species could be visualized using GFP-nos 1 3'UTR mRNA. GFP-olvas 3'UTR mRNA did not identify PGCs in herring or loach embryos, but did enable visualization of the PGCs in medaka embryos. Our results indicate that the 3'UTR of the zebrafish nos1 mRNA can promote maintenance of RNAs in the PGCs of different fish species. Finally, we describe and compare the migration routes of PGCs in seven teleost species.     

Generation of germ-line chimera zebrafish using primordial germ cells isolated from cultured blastomeres and cryopreserved embryoids

Primordial germ cells (PGCs) are the only cells in developing embryos with the potential to transmit genetic information to the next generation. In our previous study, a single PGC transplanted into a host differentiated into fertile gametes and produced germ-line chimeras of cyprinid fish, including zebrafish. In this study, we aimed to induce germ-line chimeras by transplanting donor PGCs from various sources (normal embryos at different stages, dissociated blastomeres, embryoids, or embryoids cryopreserved by vitrification) into host blastulae, and compare the migration rates of the PGCs towards the gonadal ridge. Isolated, cultured blastomeres not subject to mesodermal induction were able to differentiate into PGCs that retained their motility. Moreover, these PGCs successfully migrated towards the gonadal ridge of the host and formed viable gametes. Motility depended on developmental stage and culture duration: PGCs obtained at earlier developmental stages and with shorter cultivation periods showed an increased rate of migration to the gonadal ridge. Offspring were obtained from natural spawning between normal females and chimeric males. These results provide the basis for new methods of gene preservation in zebrafish.     

Establishment of Multi-Site Infection Model in Zebrafish Larvae for Studying Staphylococcus aureus Infectious Disease

Zebrafish(Danio rerio) is an ideal model for studying the mechanism of infectious disease and the interaction between host and pathogen.As a teleost,zebrafish has developed a complete immune system which is similar to mammals.Moreover,the easy acquirement of large amounts of transparent embryos makes it a good candidate for gene manipulation and drug screening.In a zebrafish infection model,all of the site,timing,and dose of the bacteria microinjection into the embryo are important factors that determine the bacterial infection of host.Here,we established a multi-site infection model in zebrafish larvae of 36 hours post-fertilization(hpf) by micro-injecting wild-type or GFP-expressing Staphylococcus aereus(5.aureus) with gradient burdens into different embryo sites including the pericardial cavity(PC),eye,the fourth hindbrain ventricle(4V),yolk circulation valley(YCV),caudal vein(CV),yolk body(YB),and Duct of Cuvier(DC) to resemble human infectious disease.With the combination of GFP-expressing S.aureus and transgenic zebrafish Tg(corola:eGFP;lyz:Dsred) and Tg(lyz:Dsred) lines whose macrophages or neutrophils are fluorescent labeled,we observed the dynamic process of bacterial infection by in vivo multicolored confocal fluorescence imaging.Analyses of zebrafish embryo survival, bacterial proliferation and myeloid cells phagocytosis show that the site- and dose-dependent differences exist in infection of different bacterial entry routes.This work provides a consideration for the future study of pathogenesis and host resistance through selection of multi-site infection model.More interaction mechanisms between pathogenic bacteria virulence factors and the immune responses of zebrafish could be determined through zebrafish multi-site infection model.     

Germ cell migration in zebrafish is cyclopamine-sensitive but Smoothened-independent

Primordial germ cells (PGCs) are the progenitors of reproductive cells in metazoans and are an important model for the study of cell migration in vivo. Previous reports have suggested that Hedgehog (Hh) protein acts as a chemoattractant for PGC migration in the Drosophila embryo and that downstream signaling proteins such as Patched (Ptc) and Smoothened (Smo) are required for PGC localization to somatic gonadal precursors. Here we interrogate whether Hh signaling is required for PGC migration in vertebrates, using the zebrafish as a model system. We find that cyclopamine, an inhibitor of Hh signaling, causes strong defects in the migration of PGCs in the zebrafish embryo. However, these defects are not due to inhibition of Smoothened (Smo) by cyclopamine; rather, we find that neither maternal nor zygotic Smo is required for PGC migration in the zebrafish embryo. Cyclopamine instead acts independently of Smo to decrease the motility of zebrafish PGCs, in part by dysregulating cell adhesion and uncoupling cell polarization and translocation. These results demonstrate that Hh signaling is not required for zebrafish PGC migration, and underscore the importance of regulated cell-cell adhesion for cell migration in vivo.