Name: hyperactive piggybac transposase-mediated germline transformation in the fall armyworm, spodoptera frugiperda
Uploaded: 2021-09-23T14:00:00
Description: Watch this Scientific Journal Video about Hyperactive piggyBac Transposase-mediated Germline Transformation in the Fall Armyworm, Spodoptera frugiperda at JoVE.com

The research reported is supported by the National Science Foundation I/UCRC, the Center for Arthropod Management Technologies, under Grant No IIP-1821936 and by industry partners, Agriculture and Food Research Initiative Competitive Grant No. 2019-67013-29351 and the National Institute of Food and Agriculture, US Department of Agriculture (2019-67013-29351 and 2353057000).

1. In vitro synthesis of hyPBase mRNA
NOTE: The complete coding sequence of the hyPBase sequence was synthesized and inserted into a pTD1-Cas9 vector (see the Table of Materials) to produce the pTD1-hyPBase construct, which contains a hyPBase-expressing cassette, T7 promoter: polyhedrin-5&#39; UTR: hyPBase: polyhedrin-3&#39; UTR: poly (A). The full sequence of the pTD1-hyPBase construct is provided in the Supplementary Material.
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The low rate of transposition and difficulty of delivering transgenic components into fresh embryos limit the success of germline transformation in many non-model insects, especially those from order, Lepidoptera. To increase the germline transformation rate, a hyperactive version of the most widely used piggyBac transposase (hyPBase) was developed7,10. To date, successful germline transformation in lepidopteran insects is mainly reported in the model in...

The fall armyworm (FAW), Spodoptera frugiperda, is native to tropical and subtropical regions of America. Currently, this is a devastating insect herbivore in more than 100 countries worldwide1. FAW larvae feed on more than 350 host plants, including some important staple food crops2. The strong migration ability of FAW adults contributes to its recent rapid spread from the Americas to other places1,2. As a result, this insect is now threatening food security internationally. Applying new technologies may facilitate advanced studies in FAW and provide novel strategies to manage this pest.
Insect germline transformation has been used to study gene function and generate transgenic insects for use in genetic control3,4. Among the various methods used to achieve genetic transformation in insects, the piggyBac element-based method is the most used method5. However, due to the low rate of transposition, it is still challenging to conduct transgenesis in non-model insects. Recently, a hyperactive version of piggyBac transposase (hyPBase) was developed6,7. Germline transformation was achieved in FAW recently8, which is the first report that used the hyPBase in lepidopteran insects. In this report, detailed information on employing hyPBase mRNA in generating transgenic FAW is described. The method described here could be applied to achieve the transformation of other lepidopteran insects.

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hyperactive piggybac transposase-mediated germline transformation in the fall armyworm, spodoptera frugiperda

Stable insertion of genetic cargo into insect genomes using transposable elements is a powerful tool for functional genomic studies and developing genetic pest management strategies. The most used transposable element in insect transformation is piggyBac, and piggyBac-based germline transformation has been successfully conducted in model insects. However, it is still challenging to employ this technology in non-model insects that include agricultural pests. This paper reports on germline transformation of a global agricultural pest, the fall armyworm (FAW), Spodoptera frugiperda, using the hyperactive piggyBac transposase (hyPBase).
In this work, the hyPBase mRNA was produced and used in place of helper plasmid in embryo microinjections. This change led to the successful generation of transgenic FAW. Furthermore, the methods of screening transgenic animals, PCR-based rapid detection of transgene insertion, and thermal asymmetric interlaced PCR (TAIL-PCR)-based determination of the integration site, are also described. Thus, this paper presents a protocol to produce transgenic FAW, which will facilitate piggyBac-based transgenesis in FAW and other lepidopteran insects.

A construct for the expression of hyPBase-containing T7 promoter: polyhedrin-5&#39;UTR: hyPBase: polyhedrin-3&#39;UTR: poly (A) signal was generated (Figure 1A) and amplified as a ~2.2 kb PCR fragment to synthesize hyPBase mRNA in vitro (Figure 1B). Then, the hyPBase mRNA was produced and subjected to agarose gel electrophoresis. The mRNA of the expected size (~1.1 kb band) was detected on a 1% agarose gel (Figure 1C).
...

Watch this Scientific Journal Video about Hyperactive piggyBac Transposase-mediated Germline Transformation in the Fall Armyworm, Spodoptera frugiperda at JoVE.com

Hyperactive piggyBac Transposase-mediated Germline Transformation in the Fall Armyworm, Spodoptera frugiperda

Successful germline transformation in the fall armyworm, Spodoptera frugiperda, was achieved using mRNA of hyperactive piggyBac transposase.

Hyperactive piggyBac Transposase-mediated Germline Transformation in the Fall Armyworm, Spodoptera frugiperda

Stable insertion of genetic cargo into insect genomes using transposable elements is a powerful tool for functional genomic studies and developing genetic ...

This protocol shows production of transgenic Fall Armyworm using piggyBac-based transformation system. We hope that these methods will benefit improving transformation, not only in the Fall Armyworm, but also lepidopteran insects. The method described here makes the germline transformation of lepidopteran pest insects efficient.Demonstrating the procedure will be Dr.Xien Chen, a postdoctoral fellow in my laboratory. Begin by placing 12 male pupae and 12 female pupae in a box. Place a 10%sucrose solution in the box for feeding adults.Cover the box with a paper towel. On day two post-eclosion, expose the adults to intense light overnight. On day three post-eclosion, transfer the adults to a dark place.Collect the embryos within two hours after over position. Add drops of water to the piece of the paper towel with fresh eggs kept in a Petri dish on ice. Transfer the eggs gently to a glass slide with a fine brush and align them one by one on a glass slide.Keep the glass slides with the eggs aligned on ice before microinjection. Inject a mixture of the 200 nanograms per microliter piggyBac-based EGFP expressing plasmid, 200 nanograms per microliter hyperactive piggyBac transposase mRNA, and sterile distilled water into the eggs using the compensation pressure of the automated microinjector. Keep the injected eggs at 27 plus or minus one degree Celsius, 60 plus or minus 10%relative humidity until hatching.Feed the hatched larvae on an artificial diet, and transfer each larva to one small cup at the early curd and star stage. Collect the pupae and place approximately 150 female and 150 male pupae in a cage. Hang several pieces of paper towels 30 centimeters by 15 centimeters in size in the cage to collect the eggs.Collect the paper towels with eggs daily, and keep the eggs in appropriate conditions until hatching. Keep the neonate larvae at four degrees Celsius for five minutes to immobilize them, and then transfer them onto an ice cold plate. Screen the immobilized neonate larvae under a fluorescence stereo microscope.Select the EGFP-positive neonates, raise them to the pupal stage, in around two weeks at 27 plus or minus one degree Celsius. The hyperactive piggyBac transposase mRNA synthesized in vitro was detected using a 1%Agarose gel. The PDS-injected embryos did not show EGFP signal, whereas the EGFP-expressing plasmid and hyperactive piggyBac transposase mRNA-injected embryos showed EGP fluorescence, indicating that the piggyBac construction was successful.The G1 larvae obtained from eggs resulting from a self-cross of G0 adults showed a strong EGFP signal. A fragment containing the promoter and EGFP fragment was successfully amplified using the genomic DNA isolated from the EGFP-positive larvae as a template. However, the same fragment was not detected when genomic DNA was isolated from the wild-type larvae as the template.The eggs for microinjection should be as fresh as possible and must always be kept on ice before microinjection to slow down their development. This technique paves the way for researchers to answer questions in pest insect functional genomics and develop genetic control methods for this global pest.

hyperactive-piggybac-transposase-mediated-germline-transformation

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Biology

Brain Slice Stimulation Using a Microfluidic Network and Standard Perfusion Chamber

We have demonstrated the fabrication of a two-level microfluidic device that can be easily integrated with existing electrophysiology setups. The two-level microfluidic device is fabricated using a two-step standard negative resist lithography process 1. The first level contains microchannels with inlet and outlet ports at each end. The second level contains microscale circular holes located midway of the channel length and centered along with channel width. Passive pumping method is used to pump fluids from the inlet port to the outlet port 2. The microfluidic device is integrated with off-the-shelf perfusion chambers and allows seamless integration with the electrophysiology setup. The fluids introduced at the inlet ports flow through the microchannels towards the outlet ports and also escape through the circular openings located on top of the microchannels into the bath of the perfusion. Thus the bottom surface of the brain slice placed in the perfusion chamber bath and above the microfluidic device can be exposed with different neurotransmitters. The microscale thickness of the microfluidic device and the transparent nature of the materials [glass coverslip and PDMS (polydimethylsiloxane)] used to make the microfluidic device allow microscopy of the brain slice. The microfluidic device allows modulation (both spatial and temporal) of the chemical stimuli introduced to the brain slice microenvironments.

We demonstrate fabrication of a simple microfluidic device that can be integrated with standard electrophysiology setups to expose microscale surfaces of a brain slice in a well controlled manner to different neurotransmitters.

We have demonstrated the fabrication of a two-level microfluidic device that can be easily integrated with existing electrophysiology setups. The ...

Genomic Transformation of the Picoeukaryote Ostreococcus tauri

Common problems hindering rapid progress in Plant Sciences include cellular, tissue and whole organism complexity, and notably the high level of genomic redundancy affecting simple genetics in higher plants. The novel model organism Ostreococcus tauri is the smallest free-living eukaryote known to date, and possesses a greatly reduced genome size and cellular complexity1,2, manifested by the presence of just one of most organelles (mitochondrion, chloroplast, golgi stack) per cell, and a genome containing only ~8000 genes. Furthermore, the combination of unicellularity and easy culture provides a platform amenable to chemical biology approaches. Recently, Ostreococcus has been successfully employed to study basic mechanisms underlying circadian timekeeping3-6. Results from this model organism have impacted not only plant science, but also mammalian biology7. This example highlights how rapid experimentation in a simple eukaryote from the green lineage can accelerate research in more complex organisms by generating testable hypotheses using methods technically feasible only in this background of reduced complexity. Knowledge of a genome and the possibility to modify genes are essential tools in any model species. Genomic1, Transcriptomic8, and Proteomic9 information for this species is freely available, whereas the previously reported methods6,10 to genetically transform Ostreococcus are known to few laboratories worldwide.
In this article, the experimental methods to genetically transform this novel model organism with an overexpression construct by means of electroporation are outlined in detail, as well as the method of inclusion of transformed cells in low percentage agarose to allow selection of transformed lines originating from a single transformed cell. Following the successful application of Ostreococcus to circadian research, growing interest in Ostreococcus can be expected from diverse research areas within and outside plant sciences, including biotechnological areas. Researchers from a broad range of biological and medical sciences that work on conserved biochemical pathways may consider pursuing research in Ostreococcus, free from the genomic and organismal complexity of larger model species.

Genomic Transformation of the Picoeukaryote Ostreococcus tauri

This article describes genetic transformation of the unicellular marine alga Ostreococcus tauri by electroporation. This eukaryotic organism is an effective model platform for higher plants, possesing greatly reduced genomic and cellular complexity and being readily amenable to both cell culture and chemical biology.

Common problems hindering rapid progress in Plant Sciences include cellular, tissue and whole organism complexity, and notably the high level of genomic ...

Identification of Metabolically Active Bacteria in the Gut of the Generalist Spodoptera littoralis via DNA Stable Isotope Probing Using 13C-Glucose

Guts of most insects are inhabited by complex communities of symbiotic nonpathogenic bacteria. Within such microbial communities it is possible to identify commensal or mutualistic bacteria species. The latter ones, have been observed to serve multiple functions to the insect, i.e. helping in insect reproduction1, boosting the immune response2, pheromone production3, as well as nutrition, including the synthesis of essential amino acids4, among others. &#160; &#160;
Due to the importance of these associations, many efforts have been made to characterize the communities down to the individual members. However, most of these efforts were either based on cultivation methods or relied on the generation of 16S rRNA gene fragments which were sequenced for final identification. Unfortunately, these approaches only identified the bacterial species present in the gut and provided no information on the metabolic activity of the microorganisms.
To characterize the metabolically active bacterial species in the gut of an insect, we used stable isotope probing (SIP) in vivo employing 13C-glucose as a universal substrate. This is a promising culture-free technique that allows the linkage of microbial phylogenies to their particular metabolic activity. This is possible by tracking stable, isotope labeled atoms from substrates into microbial biomarkers, such as DNA and RNA5. The incorporation of 13C isotopes into DNA increases the density of the labeled DNA compared to the unlabeled (12C) one. In the end, the 13C-labeled DNA or RNA is separated by density-gradient ultracentrifugation from the 12C-unlabeled similar one6. Subsequent molecular analysis of the separated nucleic acid isotopomers provides the connection between metabolic activity and identity of the species.
Here, we present the protocol used to characterize the metabolically active bacteria in the gut of a generalist insect (our model system), Spodoptera littoralis (Lepidoptera, Noctuidae). The phylogenetic analysis of the DNA was done using pyrosequencing, which allowed high resolution and precision in the identification of insect gut bacterial community. As main substrate, 13C-labeled glucose was used in the experiments. The substrate was fed to the insects using an artificial diet.

Identification of Metabolically Active Bacteria in the Gut of the Generalist Spodoptera littoralis via DNA Stable Isotope Probing Using 13C-Glucose

The active bacterial community associated with the gut of Spodoptera littoralis, was determined by stable-isotope-probing (SIP) coupled to pyrosequencing. Using this methodology, identification of the metabolically active bacteria species within the community was done with high resolution and precision.

Guts of most insects are inhabited by complex communities of symbiotic nonpathogenic bacteria. Within such microbial communities it is possible to ...

Preparing and Injecting Embryos of Culex Mosquitoes to Generate Null Mutations using CRISPR/Cas9

Culex mosquitoes are the major vectors of several diseases that negatively impact human and animal health including West Nile virus and diseases caused by filarial nematodes such as canine heartworm and elephantasis. Recently, CRISPR/Cas9 genome editing has been used to induce site-directed mutations by injecting a Cas9 protein that has been complexed with a guide RNA (gRNA) into freshly laid embryos of several insect species, including mosquitoes that belong to the genera Anopheles and Aedes. Manipulating and injecting Culex mosquitoes is slightly more difficult as these mosquitoes lay their eggs upright in rafts rather than individually like other species of mosquitoes. Here we describe how to design gRNAs, complex them with Cas9 protein, induce female mosquitoes of Culex pipiens to lay eggs, and how to prepare and inject newly laid embryos for microinjection with Cas9/gRNA. We also describe how to rear and screen injected mosquitoes for the desired mutation. The representative results demonstrate that this technique can be used to induce site-directed mutations in the genome of Culex mosquitoes and, with slight modifications, can be used to generate null-mutants in other mosquito species as well.&#160;

Preparing and Injecting Embryos of Culex Mosquitoes to Generate Null Mutations using CRISPR/Cas9

CRISPR/Cas9 is increasingly used to characterize gene function in non-model organisms. This protocol describes how to generate knock-out lines of Culex pipiens, from preparing injection mixes, to obtaining and injecting mosquito embryos, as well as how to rear, cross, and screen injected mosquitoes and their progeny for desired mutations.

Culex mosquitoes are the major vectors of several diseases that negatively impact human and animal health including West Nile virus and diseases caused by ...

Microsurgical Obstruction of Testes Fusion in Spodoptera litura

Instead of using genetic methods like RNA interference (RNAi) and clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated endonuclease Cas9, a physical barrier was microsurgically inserted between the testes of Spodoptera litura to study the impact of this microsurgery on its growth and reproduction. After inserting aluminum foil between the testes, insect molting during metamorphosis proceeded normally. Insect growth and development were not remarkably altered; however, the number of sperm bundles changed if testes fusion was stopped by the microsurgery. These findings imply that blocking testicular fusion can influence male reproduction capability. The method can be further applied to interrupt communication between organs to study the function of specific signaling pathways. Compared to conventional surgery, microsurgery only requires freezing anesthetization, which is preferable to carbon dioxide anesthetization. Microsurgery also minimizes the surgery site area and facilitates wound healing. However, the selection of materials with specific functions needs further investigation. Avoiding tissue injury is crucial when making incisions during the operation.

Microsurgical Obstruction of Testes Fusion in Spodoptera litura

Aluminum foil was microsurgically inserted between the testes of Spodoptera litura to obstruct the fusion of testis. The procedure includes freezing, fixing, disinfection, incision, placing the barrier, suturing, postoperative feeding, and inspection. This approach provides a method to interfere with tissue formation.

Instead of using genetic methods like RNA interference (RNAi) and clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated ...

Natural Transformation, Protein Expression, and Cryoconservation of the Filamentous Cyanobacterium Phormidium lacuna

Cyanobacteria are the focus of basic research and biotechnological projects in which solar energy is utilized for biomass production. Phormidium lacuna is a newly isolated filamentous cyanobacterium. This paper describes how new filamentous cyanobacteria can be isolated from marine rockpools. It also describes how DNA can be extracted from filaments and how the genomes can be sequenced. Although transformation is established for many single-celled species, it is less frequently reported for filamentous cyanobacteria. A simplified method for the natural transformation of P. lacuna is described here. P. lacuna is the only member of the order Oscillatoriales for which natural transformation is established. This paper also shows how natural transformation is used to express superfolder green fluorescent protein (sfGFP). An endogenous cpcB promoter induced approximately 5 times stronger expression than cpc560, A2813, or psbA2 promoters from Synechocystis sp. PCC6803. Further, a method for the cryopreservation of P. lacuna and Synechocystis sp. CPP 6803 was established, and methods for assessing motility in a liquid medium and on agar and plastic surfaces are described.

Natural Transformation, Protein Expression, and Cryoconservation of the Filamentous Cyanobacterium Phormidium lacuna

Phormidium lacuna is a filamentous cyanobacterium that was isolated from marine rockpools. This article describes the isolation of filaments from natural sources, DNA extraction, genome sequencing, natural transformation, expression of sfGFP, cryoconservation, and motility methods.

Cyanobacteria are the focus of basic research and biotechnological projects in which solar energy is utilized for biomass production. Phormidium lacuna is ...

Embryo Injection Technique for Gene Editing in the Black-Legged Tick, Ixodes scapularis

Ticks can transmit various viral, bacterial, and protozoan pathogens and are therefore considered vectors of medical and veterinary importance. Despite the growing burden of tick-borne diseases, research on ticks has lagged behind insect disease vectors due to challenges in applying genetic transformation tools for functional studies to the unique biology of ticks. Genetic interventions have been gaining attention to reduce mosquito-borne diseases. However, the development of such interventions requires stable germline transformation by injecting embryos. Such an embryo injection technique is lacking for chelicerates, including ticks. Several factors, such as an external thick wax layer on tick embryos, hard chorion, and high intra-oval pressure, are some&#160;obstacles that previously prevented embryo injection protocol development in ticks. The present work has overcome these obstacles, and an embryo injection technique for the black-legged tick, Ixodes scapularis, is described here.&#160;This technique can be used to deliver components, such as CRISPR/Cas9, for stable germline transformations.

Embryo Injection Technique for Gene Editing in the Black-Legged Tick, Ixodes scapularis

The present protocol describes a method for injecting tick embryos. Embryo injection is the preferred technique for genetic manipulation to generate transgenic lines.

Ticks can transmit various viral, bacterial, and protozoan pathogens and are therefore considered vectors of medical and veterinary importance. Despite ...

Super-Resolution Microscopy of the Synaptonemal Complex Within the Caenorhabditis elegans Germline

During meiosis, homologous chromosomes must recognize and adhere to one another to allow for their correct segregation. One of the key events that secures the interaction of homologous chromosomes is the assembly of the synaptonemal complex (SC) in meiotic prophase I. Even though there is little sequence homology between protein components within the SC among different species, the general structure of the SC has been highly conserved during evolution. In electron micrographs, the SC appears as a tripartite, ladder-like structure composed of lateral elements or axes, transverse filaments, and a central element. 
However, precisely identifying the localization of individual components within the complex by electron microscopy to determine the molecular structure of the SC remains challenging. By contrast, fluorescence microscopy allows for the identification of individual protein components within the complex. However, since the SC is only ~100 nm wide, its substructure cannot be resolved by diffraction-limited conventional fluorescence microscopy. Thus, determining the molecular architecture of the SC requires super-resolution light microscopy techniques such as structured illumination microscopy (SIM), stimulated-emission depletion (STED) microscopy, or single-molecule localization microscopy (SMLM). 
To maintain the structure and interactions of individual components within the SC, it is important to observe the complex in an environment that is close to its native environment in the germ cells. Therefore, we demonstrate an immunohistochemistry and imaging protocol that enables the study of the substructure of the SC in intact, extruded Caenorhabditis elegans germline tissue with SMLM and STED microscopy. Directly fixing the tissue to the coverslip reduces the movement of the samples during imaging and minimizes aberrations in the sample to achieve the high resolution necessary to visualize the substructure of the SC in its biological context.

Super-Resolution Microscopy of the Synaptonemal Complex Within the Caenorhabditis elegans Germline

Super-resolution microscopy can provide a detailed insight into the organization of components within the synaptonemal complex in meiosis. Here, we demonstrate a protocol to resolve individual proteins of the Caenorhabditis elegans synaptonemal complex.

During meiosis, homologous chromosomes must recognize and adhere to one another to allow for their correct segregation. One of the key events that secures ...

Agrobacterium tumefaciens-Mediated Genetic Transformation of Narrowleaf Plantain

Species in the genus Plantago have several unique traits that have led to them being adapted as model plants in various fields of study. However, the lack of a genetic manipulation system prevents in-depth investigation of gene function, limiting the versatility of this genus as a model. Here, a transformation protocol is presented for Plantago lanceolata, the most commonly studied Plantago species. Using Agrobacterium tumefaciens-mediated transformation, 3 week-old roots of aseptically grown P. lanceolata plants were infected with bacteria, incubated for 2-3 days, and then transferred to a shoot induction medium with appropriate antibiotic selection. Shoots typically emerged from the medium after 1 month, and roots developed 1-4 weeks after the shoots were transferred to the root induction medium. The plants were then acclimated to a soil environment and tested for the presence of a transgene using the &#946;-glucuronidase (GUS) reporter assay. The transformation efficiency of the current method is ~20%, with two transgenic plants emerging per 10 root tissues transformed. Establishing a transformation protocol for narrowleaf plantain will facilitate the adoption of this plant as a new model species in various areas.

Agrobacterium tumefaciens-Mediated Genetic Transformation of Narrowleaf Plantain

Because of its versatile application as a model species in various fields of study, there is a need for a genetic transformation toolkit in narrowleaf plantain (Plantago lanceolata). Here, using Agrobacterium tumefaciens-mediated transformation, a protocol is presented that results in stable transgenic lines with a transformation efficiency of 20%.

Species in the genus Plantago have several unique traits that have led to them being adapted as model plants in various fields of study. However, the lack ...

&lt;em&gt;Agrobacterium&lt;/em&gt;-Mediated Hairy Root Induction and Regeneration in Plants

Hairy Root Transformation and Regeneration in Arabidopsis thaliana and Brassica napus

Hairy root transformation represents a versatile tool for plant biotechnology in various species. Infection by an Agrobacterium strain carrying a Root-inducing (Ri) plasmid induces the formation of hairy roots at the wounding site after the transfer of T-DNA from the Ri plasmid into the plant genome. The protocol describes in detail the procedure of the injection-based hairy root induction in Brassica napus DH12075 and Arabidopsis thaliana Col-0. The hairy roots may be used to analyze a transgene of interest or processed for the generation of transgenic plants. Regeneration medium containing cytokinin 6-benzylaminopurine (5 mg/L) and auxin 1-naphthaleneacetic acid (8 mg/L) successfully elicits shoot formation in both species. The protocol covers the genotyping and selection of regenerants and T1 plants to obtain plants carrying a transgene of interest and free of T-DNA from the Ri plasmid. An alternative process leading to the formation of a composite plant is also depicted. In this case, hairy roots are kept on the shoot (instead of the natural roots), which enables the study of a transgene in hairy root cultures in the context of the whole plant.

Author Spotlight: Optimizing Hairy Root-Based Transformation Protocols for Enhanced Efficiency in Brassicaceae

The protocol describes hairy root induction using Arabidopsis primary inflorescence stems and Brassica napus hypocotyls. The hairy roots can be cultured and used as explants to regenerate transgenic plants.