This work is supported by a grant&#160;from National Natural Science Foundation of China (No.31472037). Mention of trade names or commercial products in this article is solely for the purpose of providing specific information and does not imply recommendation.

NOTE: To limit RNA degradation, prepare solutions using wet-autoclaved distilled water (at 121 &#176;C for 60 min) and also wet-autoclave materials.
1. Preparation of RNA ISH Antisense and Sense Probes
<ol>
	<li>Target gene amplification and purification
	<ol>
		<li>First, produce a 387 bp double-stranded fragment of L. migratoria OR1 (LmigOR1, GenBank: JQ766965) from the plasmid containing the full-length cDNA of LmigOR1 with a Taq DNA Po...

<ol>
	<li>Sato, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Insect+olfactory+receptors+are+heteromeric+ligand-gated+ion+channels.">Insect olfactory receptors are heteromeric ligand-gated ion channels.</a> Nature. 452 (7190), 1002-1006 (2008).</li><li>Smart, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Drosophila+odorant+receptors+are+novel+seven+transmembrane+domain+proteins+that+can+signal+independently+of+heterotrimeric+G+proteins.">Drosophila odorant receptors are novel seven transmembrane domain proteins that can signal independently of heterotrimeric G proteins.</a> Insect Biochem Mol Biol. 38 (8), 770-780 (2008).</li><li>Wicher, D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Drosophila+odorant+receptors+are+both+ligand-gated+and+cyclic-nucleotide-activated+cation+channels.">Drosophila odorant receptors are both ligand-gated and cyclic-nucleotide-activated cation channels.</a> Nature. 452 (7190), 1007-1011 (2008).</li><li>Carey, A. F., Wang, G., Su, C. Y., Zwiebel, L. J., Carlson, J. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Odorant+reception+in+the+malaria+mosquito+Anopheles+gambiae.">Odorant reception in the malaria mosquito Anopheles gambiae.</a> Nature. 464 (7258), 66-71 (2010).</li><li>Hallem, E. A., Carlson, J. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Coding+of+odors+by+a+receptor+repertoire.">Coding of odors by a receptor repertoire.</a> Cell. 125 (1), 143-160 (2006).</li><li>Wang, G., Carey, A. F., Carlson, J. R., Zwiebel, L. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Molecular+basis+of+odor+coding+in+the+malaria+vector+mosquito+Anopheles+gambiae.">Molecular basis of odor coding in the malaria vector mosquito Anopheles gambiae.</a> Proc Natl Acad Sci U S A. 107 (9), 4418-4423 (2010).</li><li>Hassanali, A., Njagi, P. G., Bashir, M. O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chemical+ecology+of+locusts+and+related+acridids.">Chemical ecology of locusts and related acridids.</a> Annu Rev Entomol. 50, 223-245 (2005).</li><li>Schaeren-Wiemers, N., Gerfin-Moser, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+single+protocol+to+detect+transcripts+of+various+types+and+expression+levels+in+neural+tissue+and+cultured+cells:+in+situ+hybridization+using+digoxigenin-labeled+cRNA+probes.">A single protocol to detect transcripts of various types and expression levels in neural tissue and cultured cells: in situ hybridization using digoxigenin-labeled cRNA probes.</a> Histochemistry. 100 (6), 431-440 (1993).</li><li>Vosshall, L. B., Amrein, H., Morozov, P. S., Rzhetsky, A., Axel, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+spatial+map+of+olfactory+receptor+expression+in+the+Drosophila+antenna.">A spatial map of olfactory receptor expression in the Drosophila antenna.</a> Cell. 96 (5), 725-736 (1999).</li><li>Yang, Y., Krieger, J., Zhang, L., Breer, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+olfactory+co-receptor+Orco+from+the+migratory+locust+(Locusta+migratoria)+and+the+desert+locust+(Schistocerca+gregaria):+identification+and+expression+pattern.">The olfactory co-receptor Orco from the migratory locust (Locusta migratoria) and the desert locust (Schistocerca gregaria): identification and expression pattern.</a> Int J Biol Sci. 8 (2), 159-170 (2012).</li><li>Schultze, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+co-expression+pattern+of+odorant+binding+proteins+and+olfactory+receptors+identify+distinct+trichoid+sensilla+on+the+antenna+of+the+malaria+mosquito+Anopheles+gambiae.">The co-expression pattern of odorant binding proteins and olfactory receptors identify distinct trichoid sensilla on the antenna of the malaria mosquito Anopheles gambiae.</a> PLoS One. 8 (7), e69412 (2013).</li><li>Xu, H., Guo, M., Yang, Y., You, Y., Zhang, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Differential+expression+of+two+novel+odorant+receptors+in+the+locust+(Locusta+migratoria).">Differential expression of two novel odorant receptors in the locust (Locusta migratoria).</a> BMC Neurosci. 14, 50 (2013).</li><li>Saina, M., Benton, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Visualizing+olfactory+receptor+expression+and+localization+in+Drosophila.">Visualizing olfactory receptor expression and localization in Drosophila.</a> Methods Mol Biol. 1003, 211-228 (2013).</li><li>Guo, M., Krieger, J., Gro&#223;e-Wilde, E., Mi&#223;bach, C., Zhang, L., Breer, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Variant+ionotropic+receptors+are+expressed+in+olfactory+sensory+neurons+of+coeloconic+sensilla+on+the+antenna+of+the+desert+locust+(Schistocerca+gregaria).">Variant ionotropic receptors are expressed in olfactory sensory neurons of coeloconic sensilla on the antenna of the desert locust (Schistocerca gregaria).</a> Int J Biol Sci. 10 (1), 1-14 (2013).</li><li>You, Y., Smith, D. P., Lv, M., Zhang, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+broadly+tuned+odorant+receptor+in+neurons+of+trichoid+sensilla+in+locust,+Locusta+migratoria.">A broadly tuned odorant receptor in neurons of trichoid sensilla in locust, Locusta migratoria.</a> Insect Biochem Mol Biol. 79, 66-72 (2016).</li><li>Jiang, X., Pregitzer, P., Grosse-Wilde, E., Breer, H., Krieger, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Identification+and+characterization+of+two+"Sensory+Neuron+Membrane+Proteins"+(SNMPs)+of+the+desert+locust,+Schistocerca+gregaria+(Orthoptera:+Acrididae).">Identification and characterization of two "Sensory Neuron Membrane Proteins" (SNMPs) of the desert locust, Schistocerca gregaria (Orthoptera: Acrididae).</a> J Insect Sci. 16 (1), 33 (2016).</li><li>Angerer, L. M., Angerer, R. C., Wilkinson, D. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+situ.+hybridization+to+cellular+RNA+with+radiolabelled+RNA+probes.">In situ. hybridization to cellular RNA with radiolabelled RNA probes.</a> In situ hybridization. , 2 (1992).</li><li>Komminoth, P., Merk, F. B., Leav, I., Wolfe, H. J., Roth, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparison+of+35S-+and+digoxigenin-labeled+RNA+and+oligonucleotide+probes+for+in+situ+hybridization.+Expression+of+mRNA+of+the+seminal+vesicle+secretion+protein+II+and+androgen+receptor+genes+in+the+rat+prostate.">Comparison of 35S- and digoxigenin-labeled RNA and oligonucleotide probes for in situ hybridization. Expression of mRNA of the seminal vesicle secretion protein II and androgen receptor genes in the rat prostate.</a> Histochemistry. 98 (4), 217-228 (1992).</li><li>Leary, J. J., Brigati, D. J., Ward, D. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rapid+and+sensitive+colorimetric+method+for+visualizing+biotin-labeled+DNA+probes+hybridized+to+DNA+or+RNA+immobilized+on+nitrocellulose:+Bio-blots.">Rapid and sensitive colorimetric method for visualizing biotin-labeled DNA probes hybridized to DNA or RNA immobilized on nitrocellulose: Bio-blots.</a> Proc Natl Acad Sci U S A. 80 (13), 4045-4049 (1983).</li><li>Hallem, E. A., Ho, M. G., Carlson, J. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+molecular+basis+of+odor+coding+in+the+Drosophila+antenna.">The molecular basis of odor coding in the Drosophila antenna.</a> Cell. 117 (7), 965-979 (2004).</li><li>Jones, W. D., Nguyen, T. A., Kloss, B., Lee, K. J., Vosshall, L. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Functional+conservation+of+an+insect+odorant+receptor+gene+across+250+million+years+of+evolution.">Functional conservation of an insect odorant receptor gene across 250 million years of evolution.</a> Curr Biol. 15 (4), R119-R121 (2005).</li></ol>

It is hard to perform RNA ISH to localize OR genes in insect antennae because the expression levels of OR genes, except ORco, are very low and preserving histological slices of insect antennae is very difficult. In addition, TSA detection is also very tricky. To address these problems, the following measures should be taken. The antennae are selected from newly molting adult locusts that have thin and soft antennal cuticles, which maintain their morphology on the slide. The frozen samples are sectioned into 12 &...

Insect antennae, which are the most important chemosensory organs, are covered with many hair-like structures &#8211; called sensilla &#8211; that are innervated by Olfactory Receptor Neurons (ORNs). On the membrane of insect ORNs, Odorant Receptors (ORs), a type of protein containing seven transmembrane domains, are expressed with a coreceptor (ORco) to form a heteromer that functions as an odorant-gated ion channel1,2,3. Different ORs respond to different combinations of chemical compounds4,5,6.
Locusts (Locusta migratoria) mainly rely on olfactory cues to trigger important behaviors7. Locust ORs are key factors for understanding molecular olfactory mechanisms. Localizing a specific locust OR gene to the neuron of a morphologically specific sensillum type by RNA In Situ&#160;Hybridization (RNA ISH) is the first step in exploring the ORs function.
RNA ISH uses a labeled complementary RNA probe to measure and localize a specific RNA sequence in section of tissue, cells or whole mounts in situ, providing insights into physiological processes and disease pathogenesis. Digoxigenin-labeled (DIG-labeled) and biotin-labeled RNA probes have been widely used in RNA hybridization. RNA labeling with digoxigenin-11-UTP or biotin-16-UTP can be prepared by in vitro transcription with SP6 and T7 RNA polymerases. DIG- and biotin-labeled RNA probes have the following advantages: non-radioactive; safe; stable; highly sensitive; highly specific; and easy to produce using PCR and in vitro transcription. DIG- and biotin-labeled RNA probes can be chromogenically and fluorescently detected. DIG-labeled RNA probes can be detected with anti-digoxigenin Alkaline Phosphatase (AP)-conjugated antibodies that can be visualized either with the highly sensitive chemiluminescent substrates nitroblue tetrazolium chloride/5-bromo-4-chloro-3-indolyl-phosphate toluidine salt (NBT/BCIP) using an optical microscope or with 2-hydroxy-3-naphtoic acid-2&#39;-phenylanilide phosphate (HNPP) coupled with 4-chloro-2-methylbenzenediazonium hemi-zinc chloride salt (Fast Red) using a confocal microscope. Biotin-labeled RNA probes can be detected with anti-biotin streptavidin Horse Radish Peroxidase (HRP)-conjugated antibodies that can be visualized with fluorescein-tyramides using a confocal microscope. Thus, double-color fluorescent in situ hybridization can be performed to detect two target genes in one slice using DIG- and biotin-labeled RNA probes.
RNA ISH with DIG- and/or biotin-labeled probes has been successfully used to localize olfactory-related genes, such as OR, ionotropic receptor, odorant-binding protein and sensory neuron membrane protein, in insect antennae of, but not limited to, Drosophila melanogaster, Anopheles gambiae, L. migratoria and the desert locust Schistocera gregaria8,9,10,11,12,13,14,15,16. However, there are two substantial challenges when performing RNA ISH for insect ORs: (1) OR genes (except ORco) are expressed at low levels and only in a few cells, making signal detection very difficult, and (2) preserving insect tissue for histology, such that the morphology is preserved and the background noise is low, can be challenging. In this paper a detailed and effective protocol describing RNA ISH for localizing OR genes in insect antennae is presented, including both chromogenic and Tyramide Signal Amplification (TSA) detection.

<table>
	<tbody>
		<tr>
			<td>Materials</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>2&#215;TSINGKETM Master Mix</td>
			<td>TSINGKE, China</td>
			<td>TSE004</td>
			<td></td>
		</tr>
		<tr>
			<td>RNase-free H2O</td>
			<td>TIANGEN, China</td>
			<td>RT121-02</td>
			<td></td>
		</tr>
		<tr>
			<td>REGULAR AGAROSE G-10</td>
			<td>BIOWEST, SPAIN</td>
			<td>91622</td>
			<td></td>
		</tr>
		<tr>
			<td>Binding buffer</td>
			<td>TIANgel Midi Purification Kit, TIANGEN, China</td>
			<td>DP209-02</td>
			<td></td>
		</tr>
		<tr>
			<td>Balance buffer</td>
			<td>TIANgel Midi Purification Kit, TIANGEN, China</td>
			<td>DP209-02</td>
			<td></td>
		</tr>
		<tr>
			<td>Wash solution</td>
			<td>TIANgel Midi Purification Kit, TIANGEN, China</td>
			<td>DP209-02</td>
			<td></td>
		</tr>
		<tr>
			<td>T Vector</td>
			<td>Promega, USA</td>
			<td>A362A</td>
			<td></td>
		</tr>
		<tr>
			<td>T4 DNA Ligase</td>
			<td>Promega, USA</td>
			<td>M180A</td>
			<td></td>
		</tr>
		<tr>
			<td>Escherichia coli DH5&#945;</td>
			<td>TIANGEN, China</td>
			<td>CB101</td>
			<td></td>
		</tr>
		<tr>
			<td>Ampicillin</td>
			<td>Sigma, USA</td>
			<td>A-6140</td>
			<td></td>
		</tr>
		<tr>
			<td>Isopropyl &#946;-D-1-thiogalactopyranoside</td>
			<td>Inalco, USA</td>
			<td>1758-1400</td>
			<td></td>
		</tr>
		<tr>
			<td>5-bromo-4-chloro-3-indolyl-&#946;-D-galactopyranoside</td>
			<td>SBS Genetech, China</td>
			<td>GX1-500</td>
			<td></td>
		</tr>
		<tr>
			<td>Nco I</td>
			<td>BioLabs, New England</td>
			<td>R0193S</td>
			<td></td>
		</tr>
		<tr>
			<td>Spe I</td>
			<td>BioLabs, New England</td>
			<td>R0133M</td>
			<td></td>
		</tr>
		<tr>
			<td>DIG RNA Labeling Kit</td>
			<td>Roche, Switzerland</td>
			<td>11175025910</td>
			<td></td>
		</tr>
		<tr>
			<td>Biotin RNA Labeling Kit</td>
			<td>Roche, Switzerland</td>
			<td>11685597910</td>
			<td></td>
		</tr>
		<tr>
			<td>DNase</td>
			<td>DIG RNA Labeling Kit, Roche, Switzerland</td>
			<td>11175025910</td>
			<td></td>
		</tr>
		<tr>
			<td>LiCl</td>
			<td>Sinopharm, China</td>
			<td>10012718</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethanol</td>
			<td>Sinopharm, China</td>
			<td>10009257</td>
			<td></td>
		</tr>
		<tr>
			<td>Acetic acid</td>
			<td>BEIJING CHEMICAL REGENTS COMPANY, China</td>
			<td>10000292</td>
			<td></td>
		</tr>
		<tr>
			<td>Tissue-Tek O.C.T. Compound</td>
			<td>Sakura Finetek Europe, Zoeterwoude, Netherlands</td>
			<td>4583</td>
			<td></td>
		</tr>
		<tr>
			<td>Slides</td>
			<td>TINA JIN HAO YANG BIOLOGCAL MANUFACTURE CO., LTE, China</td>
			<td>FISH0010</td>
			<td></td>
		</tr>
		<tr>
			<td>HCl</td>
			<td>Sinopharm, China</td>
			<td>80070591</td>
			<td></td>
		</tr>
		<tr>
			<td>Millex</td>
			<td>Millipore, USA</td>
			<td>SLGP033RS</td>
			<td></td>
		</tr>
		<tr>
			<td>Tween 20</td>
			<td>AMRESCO, USA</td>
			<td>0777-500ML</td>
			<td></td>
		</tr>
		<tr>
			<td>Nitroblue tetrazolium chloride / 5-bromo-4-chloro-3-indolyl-phosphate toluidine salt</td>
			<td>Roche, Switzerland</td>
			<td>11175041910</td>
			<td></td>
		</tr>
		<tr>
			<td>Glycerol</td>
			<td>Sinopharm, China</td>
			<td>10010618</td>
			<td></td>
		</tr>
		<tr>
			<td>Name</td>
			<td>Company</td>
			<td>Catalog Number</td>
			<td>Comments</td>
		</tr>
		<tr>
			<td>Solutions</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>1&#215;Tris-acetate-EDTA</td>
			<td>Sigma, USA</td>
			<td>V900483-1KG</td>
			<td>0.04mol/L Tris-Base</td>
		</tr>
		<tr>
			<td>1&#215;Tris-acetate-EDTA</td>
			<td>BEIJING CHEMICAL REGENTS COMPANY, China</td>
			<td>10000292</td>
			<td>0.12%acetic acid</td>
		</tr>
		<tr>
			<td>1&#215;Tris-acetate-EDTA</td>
			<td>Sigma, USA</td>
			<td>03677</td>
			<td>Ethylenediaminetetraacetic acid disodium salt (EDTA)</td>
		</tr>
		<tr>
			<td>Luria-Bertani (LB) liquid medium</td>
			<td>Sinopharm, China</td>
			<td>10019392</td>
			<td>10g/L NaCl</td>
		</tr>
		<tr>
			<td>Luria-Bertani (LB) liquid medium</td>
			<td>MERCK, Germany</td>
			<td>VM335231</td>
			<td>10g/L Peptone from casein (Tryptone)</td>
		</tr>
		<tr>
			<td>Luria-Bertani (LB) liquid medium</td>
			<td>MERCK, Germany</td>
			<td>VM361526</td>
			<td>5g/L Yeast extract</td>
		</tr>
		<tr>
			<td>LB solid substrate plate</td>
			<td>Sinopharm, China</td>
			<td>10019392</td>
			<td>10g/L NaCl</td>
		</tr>
		<tr>
			<td>LB solid substrate plate</td>
			<td>MERCK, Germany</td>
			<td>VM335231</td>
			<td>10g/L Peptone from casein (Tryptone)</td>
		</tr>
		<tr>
			<td>LB solid substrate plate</td>
			<td>MERCK, Germany</td>
			<td>VM361526</td>
			<td>5g/L Yeast extract</td>
		</tr>
		<tr>
			<td>LB solid substrate plate</td>
			<td>WISENT ING, Canada</td>
			<td>800-010-CG</td>
			<td>15g/L Agar Bacteriological Grade</td>
		</tr>
		<tr>
			<td>10&#215;phosphate buffer saline (pH7.1)</td>
			<td>Sinopharm, China</td>
			<td>10019392</td>
			<td>8.5%NaCl</td>
		</tr>
		<tr>
			<td>10&#215;phosphate buffer saline (pH7.1)</td>
			<td>Sigma, USA</td>
			<td>V900041-500G</td>
			<td>14mM KH2PO4</td>
		</tr>
		<tr>
			<td>10&#215;phosphate buffer saline (pH7.1)</td>
			<td>Sigma, USA</td>
			<td>V900268-500G</td>
			<td>80mM Na2HPO4</td>
		</tr>
		<tr>
			<td>10&#215;Tris buffered saline (pH7.5)</td>
			<td>Sigma, USA</td>
			<td>V900483-1KG</td>
			<td>1M Tris-Base</td>
		</tr>
		<tr>
			<td>10&#215;Tris buffered saline (pH7.5)</td>
			<td>Sinopharm, China</td>
			<td>10019392</td>
			<td>1.5M NaCl</td>
		</tr>
		<tr>
			<td>Detection Buffer (DAP) &#160;&#160;&#160;&#160;&#160; chromogenic detection pH9.5&#160;&#160;&#160;&#160;&#160;&#160; TSA detection pH8.0</td>
			<td>Sigma, USA</td>
			<td>V900483-1KG</td>
			<td>100mM Tris-Base</td>
		</tr>
		<tr>
			<td>Detection Buffer (DAP) &#160;&#160;&#160;&#160;&#160; chromogenic detection pH9.5&#160;&#160;&#160;&#160;&#160;&#160; TSA detection pH8.0</td>
			<td>Sinopharm, China</td>
			<td>10019392</td>
			<td>100mM NaCl</td>
		</tr>
		<tr>
			<td>Detection Buffer (DAP) &#160;&#160;&#160;&#160;&#160; chromogenic detection pH9.5&#160;&#160;&#160;&#160;&#160;&#160; TSA detection pH8.0</td>
			<td>Sigma, USA</td>
			<td>V900020-500G</td>
			<td>50mM MgCl2&#183;6H2O</td>
		</tr>
		<tr>
			<td>20&#215;saline-sodium citrate (pH7.0)</td>
			<td>Sinopharm, China</td>
			<td>10019392</td>
			<td>3M NaCl</td>
		</tr>
		<tr>
			<td>20&#215;saline-sodium citrate (pH7.0)</td>
			<td>Sigma, USA</td>
			<td>V900095-500G</td>
			<td>0.3M Na-Citrate</td>
		</tr>
		<tr>
			<td>4% paraformaldehyde solution (pH9.5)</td>
			<td>Sigma, USA</td>
			<td>V900894-100G</td>
			<td>4% paraformaldehyde</td>
		</tr>
		<tr>
			<td>4% paraformaldehyde solution (pH9.5)</td>
			<td>Sigma, USA</td>
			<td>V900182-500G</td>
			<td>0.1M NaHCO3</td>
		</tr>
		<tr>
			<td>Sodium Carbonate Buffer (pH10.2)</td>
			<td>Sigma, USA</td>
			<td>V900182-500G</td>
			<td>80mM NaHCO3</td>
		</tr>
		<tr>
			<td>Sodium Carbonate Buffer (pH10.2)</td>
			<td>Sigma, USA</td>
			<td>S7795-500G</td>
			<td>120mM Na2CO3</td>
		</tr>
		<tr>
			<td>Formamide Solution (pH10.2)</td>
			<td>MPBIO, USA</td>
			<td>FORMD002</td>
			<td>50% Deionized Formamide</td>
		</tr>
		<tr>
			<td>Formamide Solution (pH10.2)</td>
			<td></td>
			<td></td>
			<td>5&#215;saline-sodium citrate</td>
		</tr>
		<tr>
			<td>Blocking Buffer in Tris buffered saline</td>
			<td>Roche, Switzerland</td>
			<td>11175041910</td>
			<td>1% Blot</td>
		</tr>
		<tr>
			<td>Blocking Buffer in Tris buffered saline</td>
			<td>AMRESCO, USA</td>
			<td>0694-500ML</td>
			<td>0.03% Triton X-100</td>
		</tr>
		<tr>
			<td>Blocking Buffer in Tris buffered saline</td>
			<td></td>
			<td></td>
			<td>1&#215;Tris buffered saline</td>
		</tr>
		<tr>
			<td>Alkaline phosphatase solution</td>
			<td>Roche, Switzerland</td>
			<td>11175041910</td>
			<td>1.5 U/ml anti-digoxigenin alkaline phosphatase conjugated antibody</td>
		</tr>
		<tr>
			<td>Alkaline phosphatase solution</td>
			<td></td>
			<td></td>
			<td>Blocking Buffer in Tris buffered saline</td>
		</tr>
		<tr>
			<td>Alkaline phosphatase/ horse radish peroxidase solution</td>
			<td>Roche, Switzerland</td>
			<td>11175041910</td>
			<td>1.5 U/ml anti-digoxigenin alkaline phosphatase conjugated antibody</td>
		</tr>
		<tr>
			<td>Alkaline phosphatase/ horse radish peroxidase solution</td>
			<td>TSA kit, Perkin Elmer, USA</td>
			<td>NEL701A001KT</td>
			<td>1% anti-biotin streptavidin horse radish peroxidase- conjugated antibody</td>
		</tr>
		<tr>
			<td>Alkaline phosphatase/ horse radish peroxidase solution</td>
			<td></td>
			<td></td>
			<td>Blocking Buffer in Tris buffered saline</td>
		</tr>
		<tr>
			<td>Hybridization Buffer</td>
			<td>MPBIO, USA</td>
			<td>FORMD002</td>
			<td>50% Deionized Formamide</td>
		</tr>
		<tr>
			<td>Hybridization Buffer</td>
			<td></td>
			<td></td>
			<td>2&#215;saline-sodium citrate</td>
		</tr>
		<tr>
			<td>Hybridization Buffer</td>
			<td>Sigma, USA</td>
			<td>D8906-50G</td>
			<td>10% dextran sulphate</td>
		</tr>
		<tr>
			<td>Hybridization Buffer</td>
			<td>invitrogen, USA</td>
			<td>AM7119</td>
			<td>20 &#181;g/ml yeast t-RNA</td>
		</tr>
		<tr>
			<td>Hybridization Buffer</td>
			<td>Sigma, USA</td>
			<td>D3159-10G</td>
			<td>0.2 mg/ml herring sperm DNA</td>
		</tr>
		<tr>
			<td>2-hydroxy-3-naphtoic acid-2&#39;-phenylanilide phosphate/ 4-chloro-2-methylbenzenediazonium hemi-zinc chloride salt substrate</td>
			<td>Roche, Switzerland</td>
			<td>11758888001</td>
			<td>1% 2-hydroxy-3-naphtoic acid-2&#39;-phenylanilide phosphate (10mg/ml)</td>
		</tr>
		<tr>
			<td>2-hydroxy-3-naphtoic acid-2&#39;-phenylanilide phosphate/ 4-chloro-2-methylbenzenediazonium hemi-zinc chloride salt substrate</td>
			<td>Roche, Switzerland</td>
			<td>11758888001</td>
			<td>1% 4-chloro-2-methylbenzenediazonium hemi-zinc chloride salt (25mg/ml)</td>
		</tr>
		<tr>
			<td>2-hydroxy-3-naphtoic acid-2&#39;-phenylanilide phosphate/ 4-chloro-2-methylbenzenediazonium hemi-zinc chloride salt substrate</td>
			<td></td>
			<td></td>
			<td>Detection Buffer</td>
		</tr>
		<tr>
			<td>Tyramide signal amplification substrate</td>
			<td>TSA kit, Perkin Elmer, USA</td>
			<td>NEL701A001KT</td>
			<td>2% fluorescein-tyramides</td>
		</tr>
		<tr>
			<td>Tyramide signal amplification substrate</td>
			<td>TSA kit, Perkin Elmer, USA</td>
			<td>NEL701A001KT</td>
			<td>Amplification Diluent</td>
		</tr>
		<tr>
			<td>Name</td>
			<td>Company</td>
			<td>Catalog Number</td>
			<td>Comments</td>
		</tr>
		<tr>
			<td>Instrument</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Freezing microtome</td>
			<td>Leica, Nussloch, Germany</td>
			<td>Jung CM300 cryostat</td>
			<td></td>
		</tr>
		<tr>
			<td>Spectrophotometer</td>
			<td>Thermo SCIENTIFIC, USA</td>
			<td>NANODROP 2000</td>
			<td></td>
		</tr>
		<tr>
			<td>Optical microscope</td>
			<td>Olympus, Tokyo, Japan</td>
			<td>Olympus IX71microscope</td>
			<td></td>
		</tr>
		<tr>
			<td>Confocal microscope</td>
			<td>Olympus, Tokyo, Japan</td>
			<td>Olympus BX45 confocal microscope</td>
			<td></td>
		</tr>
	</tbody>
</table>

localization of odorant receptor genes in locust antennae by rna in situ hybridization

Insects have evolved sophisticated olfactory reception systems to sense exogenous chemical signals. These chemical signals are transduced by Olfactory Receptor Neurons (ORNs) housed in hair-like structures, called chemosensilla, of the antennae. On the ORNs&#39; membranes, Odorant Receptors (ORs) are believed to be involved in odor coding. Thus, being able to identify genes localized to the ORNs is necessary to recognize OR genes, and provides a fundamental basis for further functional in situ studies. The RNA expression levels of specific ORs in insect antennae are very low, and preserving insect tissue for histology is challenging. Thus, it is difficult to localize an OR to a specific type of sensilla using RNA in situ hybridization. In this paper, a detailed and highly effective RNA in situ hybridization protocol particularly for lowly expressed OR genes of insects, is introduced. In addition, a specific OR gene was identified by conducting double-color fluorescent in situ hybridization experiments using a co-expressing receptor gene, Orco, as a marker.

With chromogenic detection, a small subset of the antennal cells in every adult antennal section was denoted by the DIG-labeled LmigOR1 and LmigOR2 antisense probes (Figure 3). RNA ISH on consecutive sections to localize LmigOR1 and LmigOR2 showed that antennal cells expressing the two genes were located in ORN clusters expressing LmigORco, indicating that the putative LmigOR1 and LmigOR2 were act...

Watch this Scientific Journal Video about Localization of Odorant Receptor Genes in Locust Antennae by RNA In Situ Hybridization at JoVE.com

Localization of Odorant Receptor Genes in Locust Antennae by RNA In Situ Hybridization

This paper describes a detailed and highly effective RNA in situ hybridization protocol particularly for low-level expressed Odorant Receptor (OR) genes, as well as other genes, in insect antennae using digoxigenin (DIG)-labeled or biotin-labeled probes.

Localization of Odorant Receptor Genes in Locust Antennae by RNA In Situ Hybridization

Insects have evolved sophisticated olfactory reception systems to sense exogenous chemical signals. These chemical signals are transduced by Olfactory ...

The overall goal of this procedure is to localize low level expressed odorant receptor genes as well as other genes in the insect antennae using digoxigenin labeled or biotin labeled probes. To begin this procedure, select the new molting adult locusts that are active and have intact antennae, then cut the antennae into two to three millimeter pieces using sterile razors. Next, apply OCT compound on a freezing microtome holder and place the samples on the compound horizontally.Transfer the holder into the freezing microtome at negative 24 degrees Celsius to equilibrate until the compound freezes. Afterward, take out the holder and cover the samples with a little compound. Transfer the holder into the freezing microtome at negative 24 degrees Celsius again for at least 10 minutes, then section the frozen samples into 12 micrometer thick slices.Subsequently, thaw out the slices one by one on slides and air dry them for 10 minutes. After preparing the cryostat sections, place the slides in a plastic container and fix the tissues by incubating the slides in 4%PFA solution for 30 minutes at four degrees Celsius. After 30 minutes, wash the slides in one X PBS for one minute.To eliminate the alkaline proteins, transfer the slides to 0.2 molar hydrogen chloride for 10 minutes, then transfer the slides to one X PBS with 1%Triton X-100 for two minutes to eliminate the surface protein of nucleic acid. Next, wash the slides twice for 30 seconds in one X PBS. Subsequently, rinse the slides in formamide solution for 10 minutes at four degrees Celsius.Drain the slides and add 100 microliters of diluted antisense and sense probes, then place the cover slips on the tissue sections. Afterward, add formamide solution or one X PBS to the bottom of the box to keep the environment moist, but do not submerge the slides in the liquid. Following this, place the covered slides horizontally in a humid box and incubate at 55 degrees Celsius for 22 hours.After hybridization, remove the cover slips carefully. Wash the sides twice by gently agitating them on a rocker for 30 minutes in 0.1 X SSC at 60 degrees Celsius, then rinse the slides in one X TBS for 30 seconds. Add one milliliter of 1%blocking reagent in TBS supplemented with 0.03%Tritin X-100 on each slide and incubate for 30 minutes.Afterward, discard the blocking solution. For chromogenic detection, use blocking reagent in TBS to dilute 750 units per milliliter anti-digoxigenin-AP conjugated antibody to 1.5 units per milliliter AP solution. Subsequently, add 100 microliters of AP solution to each covered slide.For TSA detection, use blocking reagent in TBS to dilute 750 units per milliliter of anti-digoxigenin-AP conjugated antibody and anti-biotin streptavidin HRP conjugated antibody to the AP HRP solution, then add 100 microliters of AP HRP solution to each covered slide. Add the formamide solution or one X PBS to keep the box moist but not soggy. Following that, incubate the slides in a humid box for 60 minutes at 37 degrees Celsius.Wash the slides three times for five minutes in one X TBS supplemented with 0.05%TWEEN 20 on a rocker. After that, rinse the slides in DAP buffer for five minutes by leaving the plastic container on a rocker agitated gently. For chromogenic detection, add 100 microliters of NBT/BCIP substrate solution to each slide.Carefully place the cover slips onto the slides, then incubate the slides in a humid box with substrate solution for 10 minutes to overnight at 37 degrees Celsius. Check the development by looking at the slides from time to time under the microscope. When the development is ready, stop the reaction by transferring the slides into water.For TSA detection, use a syringe to move the HNPP/Fast Red substrate from the syringe filter, then add 100 microliters of HNPP/Fast Red substrate to each slide covered with a cover slip. After that, incubate the slides for 30 minutes with HNPP/Fast Red substrate at room temperature. After 30 minutes, remove the cover slips carefully and wash the slides three times for five minutes in one X TBS supplemented with 0.05%TWEEN 20.Incubate the slides with 100 microliters of TSA substrate per covered slide for 10 minutes at room temperature. Remove the cover slips carefully and wash the slides three times for five minutes in one X TBS supplemented with 0.05%TWEEN 20 before embedding the slides in PBS glycerol. For chromogenic detection, observe the tissue sections using an optical microscope.Shown here are the labeling pattern of LmigOR1 and LmigORco antisense probe on the consecutive sections of locust antenna. Here are the labeling pattern of LmigORco and LmigOR2 antisense probe on the consecutive sections of locust antenna. The illustration of the occasionally labeled dendritic-like structures are shown here.For TSA detection, observe the tissue sections using a confocal microscope. Here, two color in situ hybridization was performed on the longitudinal antennal section to illustrate the expression of LmigOR1 and LmigORco. Localization of LmigOR1 expressing cells in cell clusters expressing LmigORco confirmed its neural identity, and here is a close view of the boxed areas.Occasionally labeled dendritic-like structure is indicated by an arrow, and the circled areas indicate the olfactory receptor neurons cluster expressing LmigORco and sharing the same sensillum.

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Neuroscience

8.0K visualizações.  China Agricultural University. The overall goal of this procedure is to localize low level expressed odorant receptor genes as well as other genes in the insect antennae using digoxigenin labeled or biotin labeled probes. To begin this procedure, select the new molting adult locusts that are active and have intact antennae, then cut the antennae into two to three millimeter pieces using sterile razors. Next, apply OCT compound on a freezing microtome holder and place the samples on the compound horizontally.Transfer...