This work was supported by the National Natural Science Foundation of China (Grant Nos. 32070500, 31620103917, 31330072, and 31572325 to C.R., Sh.L.), by the Natural Science Foundation of Guangdong Province (Grant No. 2021B1515020044 and 2020A1515011267 to C.R.), by the Department of Science and Technology in Guangdong Province (Grant Nos. 2019B090905003 and 2019A0102006), by the Department of Science and Technology in Guangzhou (Grant No. 202102020110), by the Shenzhen Science and Technology Program (Grant No. KQTD20180411143628272 to Sh.L.).

The line of P. americana was initially provided by Dr. Huiling Hao. This species has been maintained with inbreeding for 30 years9.
1. Hatching and feeding of P. americana
<ol>
	<li>Collect fresh oothecae (immediately post egg-laying) of P. americana and incubate in the dark incubator at 25 &#176;C and 60% humidity for ~25 days. Then increase the temperature and humidity&#160;to 30 &#176;C and 75% 3 days before hatching.</li>
	<li>Use a sieve with 4 mm aperture to separate the hatched nymphs from oothecae.</li>
	<li>Keep the nymphs in cylindrical containers (12 cm in diameter and 10 cm in height) in the dark at 28 &#176;C, 70% humidity. Brush the inside edge of the containers with vaseline to prevent cockroaches from escaping. Provide rat food, water, and shelter (egg trays). Pay attention to the activity of the nymphs and regularly clean up the feces and debris.</li>
</ol>
2. Selection of the nymphs in proper instar
<ol>
	<li>Use a glass tube to pick out the freshly molted P. americana (white in body color). Keep them in new containers and wait for the correct stage for treatment. 
	&#8203;NOTE: After ~19 days under the above feeding conditions, the nymphs in the 3rd instars will be available for injection. The color of freshly molted cockroaches is white, and the instars are clarified by molting times.</li>
</ol>
3. Preparation of the target fragment with T7 promoters
<ol>
	<li>Using the cDNA of P. americana as a template, design paired primers to perform PCR to obtain 300-800 bp DNA fragment of the target gene9. Then clone the PCR fragment into a pTOPO vector (see Table of Materials) for sequencing.</li>
	<li>Using the target fragment DNA as a template, synthesize one new pair of primers with T7 promoter sequence (5&#39;-GGATCCTAATACGACTCACTATAGG-3&#39;) at the 5&#39; terminals and perform another round of PCR to obtain the target fragment with T7 promoters on each side9.</li>
</ol>
4. Transcription and synthesis of dsRNA in vitro
<ol>
	<li>Add 10 &#181;L of T7 2X Buffer, 2 &#181;L of the Enzyme Mix, T7 Express (see Table of Materials), and 2 &#181;g of PCR product (obtained in step 3.2) in the reaction system and add up the total volume to 20 &#181;L with ddH2O. Gently mix upside down manually and incubate at 37 &#176;C for 30 min and 70 &#176;C for 10 min, and then slowly cool to room temperature.</li>
	<li>Dilute RNase A solution (4 &#181;g/&#181;L) with ddH2O at a ratio of 1:200. Then add 1 &#181;L of RQ1 RNase-Free DNase (1 U/&#181;L) and 1 &#181;L of diluted RNase A solution to the system (see Table of Materials). 
	NOTE: Now, the volume of a single system is 22 &#181;L.</li>
	<li>Incubate at 37 &#176;C for 30 min. Then add 10% of the total volume (when performing N reactions simultaneously, the total volume is N x 22 &#181;L) of Sodium acetate and three volumes of the total volume of isopropanol.</li>
	<li>Gently mix upside down manually, place on ice for 5 min, and centrifuge at 13,000 x g for 10 min at 4 &#176;C.</li>
	<li>Remove the supernatant with a pipette, wash the residue with 75% ethanol (with 25% diethyl pyrocarbonate (DEPC) treated water), and then centrifuge at 13,000 x g for 5 min at 4 &#176;C.</li>
	<li>Remove supernatant again. Air-dry the pellet for 15 min at room temperature. Use ~100 &#181;L of DEPC water to dissolve dsRNA, then dilute the dsRNA to the final 2 &#181;g/&#181;L. 
	&#8203;NOTE: The dsRNA could be stored at -80 &#176;C for 6 months.</li>
</ol>
5. Loading dsRNA solution into the syringe
<ol>
	<li>Set up the program in the micro-injection pump (see Table of Materials) in advance to ensure that the volume of each injection is consistent. Before using the syringe, clean the syringe by filling it with DEPC water 8-10 times.</li>
	<li>Install the 10 &#181;L Syringe on the micro-injection pump, start the pump, and fill the syringe with 10 &#181;L of dsRNA solution (prepared at step 4.6). Inject 1 &#181;L of the dsRNA into a 3rd instar nymph (see step 2) and ensure that it does not leak out to the body.</li>
</ol>
6. Injecting dsRNA to P. americana
<ol>
	<li>Anesthetize the cockroaches with an increased concentration of CO2 in a container until the cockroaches do not move anymore, and then proceed immediately with the injection.</li>
	<li>Gently pick up the cockroach with tweezers, and deliver the cockroach toward the needle with hand. Next, insert the needle via the gap between two abdominal somites horizontally against the epidermis. About&#160;insert depth, the shallower, the better.</li>
	<li>Then, inject the dsRNA solution into the cockroach. Finally, pull out the needle tip. Ensure that the needle tip is as close as possible to the epidermis to avoid damaging internal organs. 
	NOTE: The injection should be made under a dissection microscope.</li>
	<li>Put the injected cockroaches into clean bioassay containers. Wait for about 10-20 min to let them recover from the CO2 effects. Label the containers with the date of injection, type and dose of dsRNA, and age of the P. americana.</li>
	<li>Place the injected cockroaches in a dark environment at 28 &#176;C, 70% humidity, provide water, feed, and shelter, and observe possible changes in the phenotype of the cockroaches regularly.</li>
</ol>
7. Knockdown confirmation and phenotypic analysis
<ol>
	<li>Evaluate the efficiency of RNAi using any available molecular biology techniques such as quantitative Real-Time PCR (qRT-PCR) and Western blotting. For detailed qRT-PCR and Western blotting procedures, see References1,12.</li>
	<li>To observe and analyze RNAi-related phenotypes, use the microscope suitable for living animals. 
	NOTE: RNAi may affect the morphology, behavior, molting, limb regeneration, and other physiological activities of cockroaches. The specific frequency of phenotype is calculated according to specific conditions.</li>
</ol>

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The authors declare that they have no conflicts of interest.

This report described a methodological step-by-step RNAi strategy in P. americana; of note, it also can be applied to other cockroaches (Blattella germanica, for example) and many other insects with minor changes. However, the gene silencing efficiency of RNAi is not always high enough, with an obvious disadvantage compared with the gene knockout strategy13. The following residual effect of gene-level may interfere with the real phenotypes. To ensure the RNAi treatment is success...

RNA interference (RNAi), an evolutionarily conserved mechanism, gradually becomes an essential reverse-genetic tool to inhibit gene expression in many organisms1, since Andrew Fire and Craig Mello2 developed the double-stranded RNA (dsRNA) mediated gene silence strategy. dsRNA is cleaved into fragments of 21-23 nucleotides, small interfering RNAs (siRNAs), by the enzyme Dicer in cells to activate the RNAi pathway. Then siRNAs are incorporated into the RNA-induced silencing complex (RISC), which couples to the target mRNA, causes mRNA cleavage, and finally results in the loss of gene function3,4,5. Among the insect species, many systemic RNAi experiments have so far been reported in lots of insect orders, such as Orthoptera, Isoptera, Hemiptera, Coleoptera, Neuroptera, Diptera, Hymenoptera, Lepidoptera, and Blattodea5,6,7,8.
Cockroaches (Blattaria) are an essential insect family in developmental and metamorphic studies with their rapid growth cycles, strong adaptability to the environment, and high developmental plasticity9. Before discovering that RNAi was compatible with cockroaches, previous research only focused on cockroach prevention and control due to a scarcity of genetic manipulation techniques in cockroaches. The cockroach ootheca&#39;s unique structure made it challenging to perform embryo injection-based gene knockout with the CRISPR-Cas9 system. Besides, most tissues in cockroaches (such as P. americana) show robust systemic RNAi response, allowing for the rapid generation of dysfunctional phenotypes by injecting one or more targeting dsRNAs9,10,11. These features made RNAi an indispensable technique in gene functional research in P. americana.
Even though the use of RNAi in functional gene research in P. americana has been reported, no detailed or step-by-step description was available. This report provides one step-by-step operational guideline for RNAi in P. americana, useful for gene function study in other cockroaches. Furthermore, this guide is not limited to Blattodea and can be applied to many other insects with minor modifications.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>701 N 10 &#181;L Syr (26s/51/2)</td>
			<td>Hamilton</td>
			<td>PN:80300</td>
			<td>Injection</td>
		</tr>
		<tr>
			<td>Incubator</td>
			<td>Ningbo Jiangnan Instrument Factory</td>
			<td>RXZ-380A-LED</td>
			<td>For cockroaches hatching and feeding</td>
		</tr>
		<tr>
			<td>Micro-injection pump</td>
			<td>Alcott Biotechnology</td>
			<td>ALC-IP600</td>
			<td>Injection</td>
		</tr>
		<tr>
			<td>pTOPO-Blunt Cloning Kit</td>
			<td>Aidlab Biotechnology</td>
			<td>CV16</td>
			<td>For Gene clonging</td>
		</tr>
		<tr>
			<td>quantitative Real-Time PCR Systems</td>
			<td>Bio-Rad</td>
			<td>CFX Connect</td>
			<td>For qRT-PCR analysis</td>
		</tr>
		<tr>
			<td>T7 RiboMAX Express RNAi System</td>
			<td>Promega</td>
			<td>P1700</td>
			<td>For dsRNA synthesis, which contains Rnase A Solution (4 &#956;g/&#956;L), Sodium Acetate, 3.0M (pH 5.2), Enzyme Mix, T7 Express, Nuclease-Free water, Express T7 2x Buffer, RQ1 RNase-Free DNase</td>
		</tr>
		<tr>
			<td>Thermal Cyclers</td>
			<td>Bio-Rad</td>
			<td>S1000</td>
			<td>For DNA amplification</td>
		</tr>
	</tbody>
</table>

applications of rna interference in american cockroach

Cockroaches, a sanitary pest, are essential species in insect developmental and metamorphic studies due to their easy feeding and hemimetabolous characteristics. Altogether with well-annotated genome sequences, these advantages have made American cockroach, Periplaneta americana, an important hemimetabolous insect model. Limited by the shortage of knockout strategy, effective RNA interference (RNAi)-based gene knockdown becomes an indispensable technique in functional gene research of P. americana. The present protocol describes the RNAi operation techniques in P. americana. The protocol includes (1) selection of the P. americana at proper developmental stages, (2) preparation for the injection setting, (3) dsRNA injection, and (4) gene knockdown efficiency detection. RNAi is a powerful reverse genetic tool in P. americana. The majority of P. americana tissues are sensitive to extracellular dsRNA. Its simplicity allows researchers to quickly obtain dysfunctional phenotypes under one or multiple targeting dsRNA injections, enabling researchers to better use the P. americana for developmental and metamorphic studies.

Figure 1 shows a successful injection. The microinjection syringe with a micro diameter needle should be horizontally placed on the booster (Figure 1A). The needle is inserted via the gap between two abdominal somites horizontally against the epidermis (Figure 1B). Ensure that the liquid goes into the P. americana abdomen. The too steep angle of the needle will damage the internal organs (Figur...

Watch this Scientific Journal Video about Applications of RNA Interference in American Cockroach at JoVE.com

Applications of RNA Interference in American Cockroach

The present protocol describes step-by-step guidelines for the RNAi operation techniques in P. americana.

Cockroaches, a sanitary pest, are essential species in insect developmental and metamorphic studies due to their easy feeding and hemimetabolous ...

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2.4K Views.  South China Normal University. Het protocol biedt een eenvoudige manier om Amerikaanse kakkerlakken te bestuderen. Een veel voorkomende sanitaire plaag en een gunstig insect voor de traditionele Chinese geneeskunde. Het zal helpen om de moleculaire mechanismen van meerdere levensactiviteiten van Amerikaanse kakkerlakken te onderzoeken door specifieke genen neer te halen.Het belangrijkste voordeel van deze technologie is dat het genen in Amerikaanse kakkerlakken of andere soortgelijke insecten kan neerhalen die niet ...

Video: Applications of RNA Interference in American Cockroach

Transcriptional Analysis by Nascent RNA FISH of In Vivo Trophoblast Giant Cells or In Vitro Short-term Cultures of Ectoplacental Cone Explants

The placenta derives from one extra-embryonic lineage, the trophectoderm. In the peri-implantation murine blastocyst, mural trophectoderm cells differentiate into primary trophoblast giant cells (TGCs) while the polar trophectoderm overlying the inner cell mass continues to proliferate later differentiating into secondary TGCs. TGCs play a key role in developing placenta and are essential for a successful pregnancy. Investigation of transcriptional regulation of specific genes during post-implantation development can give insights into TGCs development. Cells of the ectoplacental cone (EPC) from embryos at 7-7.5 days of gestation (E7-7.5), derived from the polar trophectoderm, differentiate into secondary TGCs1. TGCs can be studied in situ, on cryostat sections of embryos at E7 although the number of TGCs is very low at this stage. An alternative means of analyzing secondary TGCs is to use short-term cultures of individual EPCs from E7 embryos. We propose a technique to investigate the transcriptional status of genes of interest both in vivo and in vitro at the single-cell level using fluorescent in situ hybridization (RNA FISH) to visualize nascent transcripts. This technique provides a direct readout of gene expression and enables assessment of the chromosomal status of TGCs, which are large endoreplicating cells. Indeed, a key feature of terminal differentiation of TGCs is that they exit the cell cycle and undergo multiple rounds of endoreplication.This approach can be applied to detect expression of any gene expressed from autosomes and/or sex chromosomes and can provide important information into developmental mechanisms as well as placental diseases.

Transcriptional  Analysis by Nascent RNA FISH of In Vivo Trophoblast Giant Cells or In Vitro Short-term Cultures of Ectoplacental Cone Explants

Trophoblast giant cells (TGCs) play a key role in the placenta to ensure a healthy pregnancy. We present a protocol for assessing the transcriptional status of genes in TGCs by nascent fluorescent in situ hybridization on cryostat sections of post-implantation embryos or short-term cultures of embryonic day 7 ectoplacental cones.

The placenta derives from one extra-embryonic lineage, the trophectoderm. In the peri-implantation murine blastocyst, mural trophectoderm cells ...

Directed Differentiation of Primitive and Definitive Hematopoietic Progenitors from Human Pluripotent Stem Cells

One of the major goals for regenerative medicine is the generation and maintenance of hematopoietic stem cells (HSCs) derived from human pluripotent stem cells (hPSCs). Until recently, efforts to differentiate hPSCs into HSCs have predominantly generated hematopoietic progenitors that lack HSC potential, and instead resemble yolk sac hematopoiesis.&#160;These resulting hematopoietic progenitors may have limited utility for in vitro disease modeling of various adult hematopoietic disorders, particularly those of the lymphoid lineages. However, we have recently described methods to generate erythro-myelo-lymphoid multilineage definitive hematopoietic progenitors from hPSCs using a stage-specific directed differentiation protocol, which we outline here. Through enzymatic dissociation of hPSCs on basement membrane matrix-coated plasticware, embryoid bodies (EBs) are formed. EBs are differentiated to mesoderm by recombinant BMP4, which is subsequently specified to the definitive hematopoietic program by the GSK3&#946; inhibitor, CHIR99021. Alternatively, primitive hematopoiesis is specified by the PORCN inhibitor, IWP2. Hematopoiesis is further driven through the addition of recombinant VEGF and supportive hematopoietic cytokines. The resulting hematopoietic progenitors generated using this method have the potential to be used for disease and developmental modeling, in vitro.

Here, we present human pluripotent stem cell (hPSC) culture protocols, used to differentiate hPSCs into CD34+ hematopoietic progenitors. This method uses stage-specific manipulation of canonical WNT signaling to specify cells exclusively to either the definitive or primitive hematopoietic program.

One of the major goals for regenerative medicine is the generation and maintenance of hematopoietic stem cells (HSCs) derived from human pluripotent stem ...

A Modified Trier Social Stress Test for Vulnerable Mexican American Adolescents

The Trier Social Stress Test (TSST) is a well validated and widely used social stressor that has been shown to induce a 2-4 fold increase in cortisol, the biological output produced by the Hypothalamic-Pituitary-Adrenal (HPA) axis in humans. While studies have explored how modifications to the TSST influence stress responsivity, few studies have created a modified TSST appropriate for vulnerable youth that elicits a significant cortisol stress response. Thus, the current study sought to modify or adjust the TSST in a culturally sensitive way for a vulnerable sample of 14 year-old adolescents. The present study took place within the context of a longitudinal birth cohort study of Mexican American families in California called the Center for the Health Assessment of Mothers and Children of Salinas (CHAMACOS). The CHAMACOS sample was optimal to test the effectiveness of a modified culturally appropriate TSST, as it is comprised of Mexican American youth, who are often excluded from research. These youths also have experienced significant early life adversity. Example modifications included timed prompts, alternative math tasks, use of same-ethnicity peers as confederates, debriefing immediately after the conclusion of the TSST, and using an unknown youth examiner to administer the debrief. Saliva samples were collected at baseline (after a resting phase), and then again at 15, 30, and 45 min post-TSST onset to assess cortisol concentration. A pilot study of 50 participants (50% female) have been analyzed for cortisol reaction to the TSST. Results confirmed that this modified version of the TSST was successful at eliciting a significant cortisol reaction, with a wide range of variability likely due to individual differences. Goals for modifications and ethnicity considerations are discussed. This study provides the foundation for future research to utilize a modified TSST with vulnerable youth.

Here, we present a protocol that provoked cortisol reactivity in a vulnerable adolescent Mexican American sample utilizing a modified version of the Trier Social Stress Test (TSST). Saliva samples were collected at baseline, 15, 30, and 45 min post-TSST onset. Future research could utilize this modified TSST with vulnerable youth.

The Trier Social Stress Test (TSST) is a well validated and widely used social stressor that has been shown to induce a 2-4 fold increase in cortisol, the ...

Dissection and Immunofluorescent Staining of Mushroom Body and Photoreceptor Neurons in Adult Drosophila melanogaster Brains

Nervous system development involves a sequential series of events that are coordinated by several signaling pathways and regulatory networks. Many of the proteins involved in these pathways are evolutionarily conserved between mammals and other eukaryotes, such as the fruit fly Drosophila melanogaster, suggesting that similar organizing principles exist during the development of these organisms. Importantly, Drosophila has been used extensively to identify cellular and molecular mechanisms regulating processes that are required in mammals including neurogenesis, differentiation, axonal guidance, and synaptogenesis. Flies have also been used successfully to model a variety of human neurodevelopmental diseases. Here we describe a protocol for the step-by-step microdissection, fixation, and immunofluorescent localization of proteins within the adult Drosophila brain. This protocol focuses on two example neuronal populations, mushroom body neurons and retinal photoreceptors, and includes optional steps to trace individual mushroom body neurons using Mosaic Analysis with a Repressible Cell Marker (MARCM) technique. Example data from both wild-type and mutant brains are shown along with a brief description of a scoring criteria for axonal guidance defects. While this protocol highlights two well-established antibodies for investigating the morphology of mushroom body and photoreceptor neurons, other Drosophila brain regions and the localization of proteins within other brain regions can also be investigated using this protocol.

Dissection and Immunofluorescent Staining of Mushroom Body and Photoreceptor Neurons in Adult Drosophila melanogaster Brains

This protocol describes the dissection and immunostaining of adult Drosophila melanogaster brain tissues. Specifically, this protocol highlights the use of Drosophila mushroom body and photoreceptor neurons as example neuronal subsets that can be accurately used to uncover general principles underlying many aspects of neuronal development.

Nervous system development involves a sequential series of events that are coordinated by several signaling pathways and regulatory networks. Many of the ...

Processing of Human Cardiac Tissue Toward Extracellular Matrix Self-assembling Hydrogel for In Vitro and In Vivo Applications

Acellular extracellular matrix preparations are useful for studying cell-matrix interactions and facilitate regenerative cell therapy applications. Several commercial extracellular matrix products are available as hydrogels or membranes, but these do not possess tissue-specific biological activity. Because perfusion decellularization is usually not possible with human heart tissue, we developed a 3-step immersion decellularization process. Human myocardial slices procured during surgery are first treated with detergent-free hyperosmolar lysis buffer, followed by incubation with the ionic detergent, sodium dodecyl sulfate, and the process is completed by exploiting the intrinsic DNase activity of fetal bovine serum. This technique results in cell-free sheets of cardiac extracellular matrix with largely preserved fibrous tissue architecture and biopolymer composition, which were shown to provide specific environmental cues to cardiac cell populations and pluripotent stem cells. Cardiac extracellular matrix sheets can then be further processed into a microparticle powder without further chemical modification, or, via short-term pepsin digestion, into a self-assembling cardiac extracellular matrix hydrogel with preserved bioactivity.

Processing of Human Cardiac Tissue Toward Extracellular Matrix Self-assembling Hydrogel for In Vitro and In Vivo Applications

This protocol describes the complete decellularization of human myocardium while preserving its extracellular matrix components. Further processing of the extracellular matrix results in the production of microparticles and a cytoprotective self-assembling hydrogel.

Acellular extracellular matrix preparations are useful for studying cell-matrix interactions and facilitate regenerative cell therapy applications. ...

Genetic Engineering of Primary Mouse Intestinal Organoids Using Magnetic Nanoparticle Transduction Viral Vectors for Frozen Sectioning

Intestinal organoid cultures provide a unique opportunity to investigate intestinal stem cell and crypt biology in vitro, although efficient approaches to manipulate gene expression in organoids have made limited progress in this arena. While CRISPR/Cas9 technology allows for precise genome editing of cells for organoid generation, this strategy requires extensive selection and screening by sequence analysis, which is both time-consuming and costly. Here, we provide a detailed protocol for efficient viral transduction of intestinal organoids. This approach is rapid and highly efficient, thus decreasing the time and expense inherent in CRISPR/Cas9 technology. We also present a protocol to generate frozen sections from intact organoid cultures for further analysis with immunohistochemical or immunofluorescent staining, which can be used to confirm gene expression or silencing. After successful transduction of viral vectors for gene expression or silencing is achieved, intestinal stem cell and crypt function can be rapidly assessed. Although most organoid studies employ in vitro assays, organoids can also be delivered to mice for in vivo functional analyses. Moreover, our approaches are advantageous for predicting therapeutic responses to drugs because currently available therapies generally function by modulating gene expression or protein function rather than altering the genome.

We describe step-by-step instructions to: 1) efficiently engineer intestinal organoids using magnetic nanoparticles for lenti- or retroviral transduction, and, 2) generate frozen sections from engineered organoids. This approach provides a powerful tool to efficiently alter gene expression in organoids for investigation of downstream effects.

Intestinal organoid cultures provide a unique opportunity to investigate intestinal stem cell and crypt biology in vitro, although efficient approaches to ...

RNA-based Reprogramming of Human Primary Fibroblasts into Induced Pluripotent Stem Cells

Induced pluripotent stem cells (iPSCs) have proven to be a valuable tool to study human development and disease. Further advancing iPSCs as a regenerative therapeutic requires a safe, robust, and expedient reprogramming protocol. Here, we present a clinically relevant, step-by-step protocol for the extremely high-efficiency reprogramming of human dermal fibroblasts into iPSCs using a non-integrating approach. The core of the protocol consists of expressing pluripotency factors (SOX2, KLF4, cMYC, LIN28A, NANOG, OCT4-MyoD fusion) from in vitro transcribed messenger RNAs synthesized with modified nucleotides (modified mRNAs). The reprogramming modified mRNAs are transfected into primary fibroblasts every 48 h together with mature embryonic stem cell-specific microRNA-367/302 mimics for two weeks. The resulting iPSC colonies can then be isolated and directly expanded in feeder-free conditions. To maximize efficiency and consistency of our reprogramming protocol across fibroblast samples, we have optimized various parameters including the RNA transfection regimen, timing of transfections, culture conditions, and seeding densities. Importantly, our method generates high-quality iPSCs from most fibroblast sources, including difficult-to-reprogram diseased, aged, and/or senescent samples.

Here we describe a clinically relevant, high-efficiency, feeder-free method to reprogram human primary fibroblasts into induced pluripotent stem cells using modified mRNAs encoding reprogramming factors and mature microRNA-367/302 mimics. Also included are methods to assess reprogramming efficiency, expand clonal iPSC colonies, and confirm expression of the pluripotency marker TRA-1-60.

Induced pluripotent stem cells (iPSCs) have proven to be a valuable tool to study human development and disease. Further advancing iPSCs as a regenerative ...

Dissection of the Drosophila Pupal Retina for Immunohistochemistry, Western Analysis, and RNA Isolation

The Drosophila pupal retina provides an excellent model system for the study of morphogenetic processes during development. In this paper, we present a reliable protocol for the dissection of the delicate Drosophila pupal retina. Our surgical approach utilizes readily-available microdissection tools to open pupae and precisely extract eye-brain complexes. These can be fixed, subjected to immunohistochemistry, and retinas then mounted onto microscope slides and imaged if the goal is to detect cellular or subcellular structures. Alternatively, unfixed retinas can be isolated from brain tissue, lysed in appropriate buffers and utilized for protein gel electrophoresis or mRNA extraction (to assess protein or gene expression, respectively). Significant practice and patience may be required to master the microdissection protocol described, but once mastered, the protocol enables relatively quick isolation of mainly undamaged retinas.

Dissection of the Drosophila Pupal Retina for Immunohistochemistry, Western Analysis, and RNA Isolation

This paper presents a surgical method for dissecting Drosophila pupal retinas along with protocols for the processing of tissue for immunohistochemistry, western analysis, and RNA-extraction.&#160;

The Drosophila pupal retina provides an excellent model system for the study of morphogenetic processes during development. In this paper, we present a ...

Dissection, Culture and Analysis of Primary Cranial Neural Crest Cells from Mouse for the Study of Neural Crest Cell Delamination and Migration

Over the past several decades there has been an increased availability of genetically modified mouse models used to mimic human pathologies. However, the ability to study cell movements and differentiation in vivo is still very difficult. Neurocristopathies, or disorders of the neural crest lineage, are particularly challenging to study due to a lack of accessibility of key embryonic stages and the difficulties in separating out the neural crest mesenchyme from adjacent mesodermal mesenchyme. Here, we set out to establish a well-defined, routine protocol for the culture of primary cranial neural crest cells. In our approach we dissect out the mouse neural plate border during the initial neural crest induction stage. The neural plate border region is explanted and cultured. The neural crest cells form in an epithelial sheet surrounding the neural plate border, and by 24 h after explant, begin to delaminate, undergoing an epithelial-mesenchymal transition (EMT) to become fully motile neural crest cells. Due to our two-dimensional culturing approach, the distinct tissue populations (neural plate versus premigratory and migratory neural crest) can be readily distinguished. Using live imaging approaches, we can then identify changes in neural crest induction, EMT and migratory behaviors. The combination of this technique with genetic mutants will be a very powerful approach for understanding normal and pathological neural crest cell biology.

This protocol describes the dissection and culture of cranial neural crest cells from mouse models, primarily for the study of cell migration. We describe the live imaging techniques used and the analysis of speed and cell shape changes.

Over the past several decades there has been an increased availability of genetically modified mouse models used to mimic human pathologies. However, the ...

Preparation of Small RNA Libraries for Sequencing from Early Mouse Embryos

MicroRNAs (miRNAs) are important for the complex regulation of cell fate decisions and developmental timing. In vivo studies of the contribution of miRNAs during early development are technically challenging due to the limiting cell number. Moreover, many approaches require a miRNA of interest to be defined in assays such as northern blotting, microarray, and qPCR. Therefore, the expression of many miRNAs and their isoforms have not been studied during early development. Here, we demonstrate a protocol for small RNA sequencing of sorted cells from early mouse embryos to enable relatively unbiased profiling of miRNAs in early populations of neural crest cells. We overcome the challenges of low cell input and size selection during library preparation using amplification and gel-based purification. We identify embryonic age as a variable accounting for variation between replicates and stage-matched mouse embryos must be used to accurately profile miRNAs in biological replicates. Our results suggest that this method can be broadly applied to profile the expression of miRNAs from other lineages of cells. In summary, this protocol can be used to study how miRNAs regulate developmental programs in different cell lineages of the early mouse embryo.

We describe a technique for profiling microRNAs in early mouse embryos. This protocol overcomes the challenge of low cell input and small RNA enrichment. This assay can be used to analyze changes in miRNA expression over time in different cell lineages of the early mouse embryo.

MicroRNAs (miRNAs) are important for the complex regulation of cell fate decisions and developmental timing. In vivo studies of the contribution of miRNAs ...

Applications of RNA Interference in American Cockroach

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