显微注射法制备转基因家蝇技术的建立

旨在利用显微注射法对早期家蝇(Musca domestica L.)卵注射含有增强型绿色荧光蛋白(Enhanced green fluorescent protein,EGFP)基因的转座子载体,实现活体基因稳定表达并对其进行验证,为开展家蝇基因功能的研究奠定基础。文中自制适用于显微注射家蝇卵的硼硅酸盐玻璃微量注射针,摸索出家蝇卵壳的软化处理条件,以NanojectⅢ高精度微量注射器为主体构建适用于家蝇的显微注射技术平台;将含有眼部特异表达的3×P3启动子、EGFP的重组质粒PiggyBac-[3×P3]-EGFP与稳定遗传表达辅助质粒pHA3pig helper显微注射到处理过的家蝇卵中,待羽化观察眼部发光情况,检测EGFP的表达及转录水平。结果表明,将家蝇卵在漂白水中漂洗35 s时卵的正常孵化率为55%,处理35 s的卵壳其硬度适宜注射且注射针头不易破碎;羽化后的家蝇眼部带有绿色荧光的占比约为3%,通过分子检测,家蝇的DNA和RNA中均扩增出EGFP特异片段,大小为750 bp。通过该技术平台,能够便捷、有效地实现报告基因在家蝇中的稳定表达,建立以家蝇为主体的生物反应器,为后续家蝇基因功能的研究提供一定参考价值。     

Delivery of dsRNA for RNAi in insects: an overview and future directions

Abstract RNA interference (RNAi) refers to the process of exogenous double‐stranded RNA (dsRNA) silencing the complementary endogenous messenger RNA. RNAi has been widely used in entomological research for functional genomics in a variety of insects and its potential for RNAi‐based pest control has been increasingly emphasized mainly because of its high specificity. This review focuses on the approaches of introducing dsRNA into insect cells or insect bodies to induce effective RNAi. The three most common delivery methods, namely, microinjection, ingestion, and soaking, are illustrated in details and their advantages and limitations are summarized for purpose of feasible RNAi research. In this review, we also briefly introduce the two possible dsRNA uptake machineries, other dsRNA delivery methods and the history of RNAi in entomology. Factors that influence the specificity and efficiency of RNAi such as transfection reagents, selection of dsRNA region, length, and stability of dsRNA in RNAi research are discussed for further studies.     

Association of Antioxidant Systems in the Protection of Human Fibroblasts Against Oxygen Derived Free Radicals

The protection of human diploid fibroblasts against high oxygen tension was investigated using various combinations of the three major antioxidant enzymes: superoxide dismutase, catalase and gluthathione peroxidase. α-Tocopherol, a well-known hydrophobic antioxidant, was also tested in combination with the different enzymes. Microinjection of solutions containing different combinations of the three enzymes was compared with the injection of each single enzyme. We observed that the protections given by catalase or superoxide dismutase on the one hand, and by glutathione peroxidase on the other hand, were additive. Surprisingly, the combinations of catalase and superoxide dismutase were less effective than catalase alone and was even toxic at low SOD concentrations. Addition of α-tocopherol following the injection of any of the three enzymes was highly beneficial, but the strongest synergistic effect was obtained with glutathione peroxidase. These results stress the importance of membrane protection by α-tocopherol and indirectly by glutathione peroxidase. They also showed that any injection leading to the decrease in the O₂^?. or H₂ O ₂ concentration combined with one of these two protectors is very beneficial for the cells probably by decreasing the OH concentration. This is also proven by the very good protective effect obtained with desferrioxamine.     

High Throughput Microinjections of Sea Urchin Zygotes

Microinjection into cells and embryos is a common technique that is used to study a wide range of biological processes. In this method a small amount of treatment solution is loaded into a microinjection needle that is used to physically inject individual immobilized cells or embryos. Despite the need for initial training to perform this procedure for high-throughput delivery, microinjection offers maximum efficiency and reproducible delivery of a wide variety of treatment solutions (including complex mixtures of samples) into cells, eggs or embryos. Applications to microinjections include delivery of DNA constructs, mRNAs, recombinant proteins, gain of function, and loss of function reagents. Fluorescent or colorimetric dye is added to the injected solution to enable instant visualization of efficient delivery as well as a tool for reliable normalization of the amount of the delivered solution. The described method enables microinjection of 100-400 sea urchin zygotes within 10-15 min.     

Gene Transfer to the Developing Mouse Inner Ear by In Vivo Electroporation

The mammalian inner ear has 6 distinct sensory epithelia: 3 cristae in the ampullae of the semicircular canals; maculae in the utricle and saccule; and the organ of Corti in the coiled cochlea. The cristae and maculae contain vestibular hair cells that transduce mechanical stimuli to subserve the special sense of balance, while auditory hair cells in the organ of Corti are the primary transducers for hearing ¹. Cell fate specification in these sensory epithelia and morphogenesis of the semicircular canals and cochlea take place during the second week of gestation in the mouse and are largely completed before birth ^2,3. Developmental studies of the mouse inner ear are routinely conducted by harvesting transgenic embryos at different embryonic or postnatal stages to gain insight into the molecular basis of cellular and/or morphological phenotypes ^4,5. We hypothesize that gene transfer to the developing mouse inner ear in utero in the context of gain- and loss-of-function studies represents a complimentary approach to traditional mouse transgenesis for the interrogation of the genetic mechanisms underlying mammalian inner ear development⁶.The experimental paradigm to conduct gene misexpression studies in the developing mouse inner ear demonstrated here resolves into three general steps: 1) ventral laparotomy; 2) transuterine microinjection; and 3) in vivo electroporation. Ventral laparotomy is a mouse survival surgical technique that permits externalization of the uterus to gain experimental access to the implanted embryos⁷. Transuterine microinjection is the use of beveled, glass capillary micropipettes to introduce expression plasmid into the lumen of the otic vesicle or otocyst. In vivo electroporation is the application of square wave, direct current pulses to drive expression plasmid into progenitor cells^8-10. We previously described this electroporation-based gene transfer technique and included detailed notes on each step of the protocol¹¹. Mouse experimental embryological techniques can be difficult to learn from prose and still images alone. In the present work, we demonstrate the 3 steps in the gene transfer procedure. Most critically, we deploy digital video microscopy to show precisely how to: 1) identify embryo orientation in utero; 2) reorient embryos for targeting injections to the otocyst; 3) microinject DNA mixed with tracer dye solution into the otocyst at embryonic days 11.5 and 12.5; 4) electroporate the injected otocyst; and 5) label electroporated embryos for postnatal selection at birth. We provide representative examples of successfully transfected inner ears; a pictorial guide to the most common causes of otocyst mistargeting; discuss how to avoid common methodological errors; and present guidelines for writing an in utero gene transfer animal care protocol.     

线虫基因显微注射和整合技术——设备、操作与指南

秀丽线虫(Caenorhabditis elegans)是研究动物遗传、个体发育和行为活动的重要模式生物,其主要优点是能够研究从分子细胞水平到整体系统水平的相关生命活动的作用机理．其中基因显微注射和整合是该领域的核心技术,广泛应用于研究线虫的基因表达、功能和基因间的相互作用等．显微注射技术使用尖端开口直径为微米级的玻璃微管,将所研究的目的DNA注射进线虫的性腺．注射的DNA被成熟的卵细胞吸收,以染色体外遗传物质的形式存在．但这种形式并不能稳定遗传,可采用基因整合技术将外源基因整合到染色体上,得到稳定遗传的线虫种系．显微注射是一项精细的实验技术,影响实验成功与否的因素较多,实际操作需要有一定的经验．在实践过程中逐步改进和完善了这项技术,在此主要介绍线虫显微注射技术的操作过程、创新方法以及注意细节．     

Act-1核心启动子转录的EGFP基因在秀丽隐杆线虫体内的表达

克隆获得的秀丽隐杆线虫(Caenorhabditis elegans)Act-1基因的核心启动子,经BglⅡ和HindⅢ限制性内切酶消化后,与用相同酶消化的pEGFP-4.1载体连接(由pEGFP-N1去掉CMV启动子形成),构建重组表达载体Pact-EGFP。通过脂质体介导转染Vero细胞,结果发现EGFP在Vero细胞中有表达,但表达量很低。通过显微注射将Pact-EGFP与pRF4共注射到C.elegans性腺,结果发现EGFP能够在C.elegans的皮层、副皮层以及咽部表达,根据表达部位不同,获得了2种转基因线虫株。研究结果显示:EGFP在C.elegans体内的表达水平明显高于在Vero细胞内的表达,表明C.elegansAct-1基因的核心启动子区域可能存在与转录水平密切相关的独特的转录调节元件。该研究为进一步实现寄生性线虫基因在C.elegans表达提供了参考。     

Melanic mutation causes a fitness decline in bean beetles infected by Wolbachia

Wolbachia cannot live outside a host, which is thought to be the reason for host‐Wolbachia coevolution toward benign parasitism, especially because the fitness of Wolbachia is traded against its host's fitness. Insect melanism has been reported to have a positive effect on pathogen resistance, but melanic mutants of Callosobruchus analis (Fabricius) and Callosobruchus chinensis (L.) (Coleoptera: Chrysomelidae) are infected with Wolbachia. Callosobruchus chinensis is infected with CI‐inducing Wolbachia, and melanic mutants exhibit fitness decline. Interestingly, this decline is not observed in C. analis melanic mutants that are infected with CI‐free Wolbachia. Our research question is whether the infection of CI‐inducing Wolbachia causes fitness decline of melanic hosts in C. analis. We examined fecundity, fertility, and longevity of C. analis melanic mutants and compared them between uninfected and infected hosts with CI‐inducing Wolbachia. Infected melanic mutants of C. analis exhibited fitness decline leading to reduced hatch rates even when parental combinations were compatible. Wolbachia can invade a host population by causing CI to decrease the fraction of uninfected hosts, but melanic mutant hosts decrease the number of infected hosts through fitness decline. Nevertheless, the melanism in hosts is not able to stop Wolbachia invasion in C. analis.     

Generation of GGTA1 Mutant Pigs by Direct Pronuclear Microinjection of CRISPR/Cas9 Plasmid Vectors

This study was conducted to confirm that 1-site and 4-site ppU6-GGTA1-gRNA CRISPR vectors together with the pCX-Flag2-NLS₁-Cas9-NLS₂ plasmid can both generate KO pigs by direct pronuclear microinjection. In total, 41 and 53 fertilized eggs were microinjected on 1-site and 4-site strategies, respectively. The 1-site construction generated a litter of 8 piglets, and 2 were mono-allelic mutant (mMt). The injection of 4-site constructions resulted in one biallelic mutant (bMt) and one mMt piglet in a litter of 7. Those 3 mMt pigs had a 4?bp deletion, 5?bp insertion, or 7?bp insertion at site I, and the bMt pig had 5 types of mutations at cleavage sites I and III. The expression of alpha-Gal on the bMt peripheral blood mononuclear cells (PBMCs) was reduced, and survival rate of bMt PBMCs was maintained as indicated by results of cultivation with sera of humans or Formosan Macaques. We concluded that mutant pigs could be generated by direct pronuclear microinjection of ppU6-GGTA1-gRNA CRISPR vectors with the pCX-Flag2-NLS₁-Cas9-NLS₂ plasmid and that the 4-site strategy has a better mutant efficiency. Porcine U6 promoter was firstly used to express KO vectors and effectively generate mutant pigs, worthily to adopt for future KO studies.     

Amphiphysin is a component of clathrin coats formed during synaptic vesicle recycling at the lamprey giant synapse

Amphiphysin is a protein enriched at mammalian synapses thought to function as a clathrin accessory factor in synaptic vesicle endocytosis. Here we examine the involvement of amphiphysin in synaptic vesicle recycling at the giant synapse in the lamprey. We show that amphiphysin resides in the synaptic vesicle cluster at rest and relocates to sites of endocytosis during synaptic activity. It accumulates at coated pits where its SH3 domain, but not its central clathrin/AP-2-binding (CLAP) region, is accessible for antibody binding. Microinjection of antibodies specifically directed against the CLAP region inhibited recycling of synaptic vesicles and caused accumulation of clathrin-coated intermediates with distorted morphology, including flat patches of coated presynaptic membrane. Our data provide evidence for an activity-dependent redistribution of amphiphysin in intact nerve terminals and show that amphiphysin is a component of presynaptic clathrin-coated intermediates formed during synaptic vesicle recycling.