This work was supported in part by grants from the National Institute of Environmental Health Sciences (ES014443 and ES017274) and AstraZeneca to KSR.

NOT: Aksi belirtilmedikçe tüm aşamalar oda sıcaklığında gerçekleştirilmelidir. Bireysel reaktifler nasıl hazırlanacağını ilgili ayrıntılar için Reaktifler bölümüne bakın. 1. Etiketleme L1 Probları NOT: Sondalar kimyasal veya PCR etiketleme etiketli olabilir. <ol><li> kimyasal etiketleme <ol><li> etidyum bromür (0.5 ug / ml) ekleyin, sonra eriyene kadar, bir mikrodalga Tris-asetat-EDTA (TAE) tamponu, ısı 0.7-1% agaroz jeli yapmak jeli soğumasına izin verin ve. Jel tepsiye dökülür tarak ekleyin ve jel, oda sıcaklığında katılaşmaya sağlar. </li><li> üreticinin protokolüne uygun olarak, 1 saat boyunca 37 ° C&#39;de CY3 ya FITC ile sneo probu (1-2 ug) etiketleyin. Not: sneo S retrotransposition tam bir döngüsünden sonra ifade Neo Vankomisine geni pliced ​​gösterir. prob boyutu ~ 1000 bp. Sneo PCR herhangi bir vektöre veya genom büyütülmüş edilebiliric DNA. Streptavidin-CY3 / FITC etiketleme reaktif hakkında bilgi almak için Malzemeler ve Reaktifler Tablo bakınız. </li><li> her kuyuya 1x DNA yükleme tamponu, yük ile etiketlenmiş sneo prob çözüm karıştırın ve 15-20 dakika boyunca 75-100 voltta çalışır. </li><li> Ultra-Violet (UV) Aydınlatıcı kullanarak prob bandı gözünüzde canlandırın. Sneo prob boyutu ayarlanabilir olduğu ve Kilit çekirdekler asit (LNA) de (Şekil 2) eklenebilir kullanılabileceğine dikkat ediniz. </li><li> Kesme çözündürülmesi ve imalatçının protokolüne göre, bir PCR Temizleme kiti kullanılarak jelden sneo prob saflaştırılması, temiz bir bıçak ile jelden sneo etiketlenmiş prob. DİKKAT: Kapak koruma kalkanları (yani, laboratuvar mont ve UV şeffaf yüz maskesi) ile vücudun her maruz parçası görüntüleme ve jel keserken. PCR ürünleri arındırmak jel bilgi için Malzeme Tablosu ve Reaktifler bakın. </li><li> Yeniden çalışma sneo 5 ul% 0.7 agaroz jeli üzerinde un etiketli sneo probu ile etiketlenmiş prob con (1.1.1 bakınız)firma büyüklüğü artışı ve sinyal yoğunluğu kaybı (Şekil 2). </li><li> Nükleaz bilgilerini H2O içinde 260 nm&#39;de absorbans ölçümü ile etiketlenmiş sneo prob miktarını ölçmek ve 10 ng sneo prob seyreltik / ul alikotları -20 ° C&#39;de saklayın alikotları. </li></ol></li><li> PCR Etiketleme (prob etiketleme için alternatif yöntem) <ol><li> Sneo spesifik primerler birleştirin (5&#39;-ggatagcattgggagatatacct-3 &#39;ve 5&#39;-attgaacaagatg gattgcacgc-3&#39;), tek bir tüp içine PCR ile: 13.6 ul nükleaz bilgilerini H2O; 0.1 ul dATP, dCTP, dGTP (10 nM); 0.05 ul dTTP (10 nM); 0.05 ul dUTP-biyotin / dUTP-FITC / CY3 (10 nM); 4 ul tampon 5x Tag git; 0.4 ul Etiket Polymerase git; 1 ul sneo şablonu (10 ng). PCR ile ilgili bilgi için Malzeme ve Reaktifler Tablo bakınız. </li><li> Numunelerin toplam sayısı ile çarpılarak her reaktif maddenin miktarını ayarlayın. </li><li> Aşağıdaki PCR bisiklet parametresini kullanıns amplifiye ve etiket sneo Probes: 2 dakika boyunca 95 ° C; 30 saniye, 30 saniye için 62 ° C, 60 sn için 72 ° C, 95 ° C 35 döngü; 2 dakika 72 ° C; belirsiz bir süre 4 ° C&#39;de tutun. Not: bağlanma sıcaklığı ayarlanabilir veya degrade PCR diğer problar için en uygun tavlama belirlemek için tamamlanabilir. </li><li> bölüm 1.1.1, yük gibi 0,7-1% jel yapmak ve bölüm 1.1.4 gibi sonda bandı görselleştirmek. </li><li> Kes ve bölüm 1.1.5 gibi etiketlenmiş sneo probu arındırmak. </li><li> Yeniden çalışma sneo 5 ul (bakınız Şekil 2) boyut artışı ve sinyal yoğunluğu kaybını doğrulamak için un etiketli sneo probu ile etiketlenmiş prob. </li><li> Nükleaz bilgilerini H2O içinde 260 nm&#39;de absorbans ölçebilecek etiketli sneo prob miktarını ölçmek ve 10 ng sneo prob seyreltik / ul alikotları </li></ol></li></ol> 2. Hazırlama Kromozom Farkları <ol><li> vektör omurgası ifade stabil klonlar oluşturmak (controStandart bir seçim yöntemleri kullanılarak L) veya retrotransposition yetkin L1. epizomal olmayan muhabir transkripsiyon çalışmaları ile bağlantısının kullanıldı birlikte 12,16, epizomal vektörleri de kullanılabilir. Stabil kontrol veya L1 vektör tam büyüme ortamı (gerektiği gibi yapılmış plaka boyutu ayarlamaları ile 10 cm plaka başına 1 x 10 6 hücre) ifade eden hücreleri büyür. HepG2 hücreleri, RPMI-1600,% 10 FBS ve higromisin 200 ug / ml,. 37 ° C&#39;de% 70 ortak akışa kadar büyümeye ve kültürler% 5 CO2. Not: büyüme ortamının seçimi, hücre tipine bağlıdır. Burada kullanılan plazmidler higromisin ve neomisin hem seçim kaseti taşıyan göz önüne alındığında, klonların stabil bir seçim higromisin seçimi neomisin ile yapılabilir, ancak neomisin miktarı, her hücre türü için tolerans seviyelerinin tutturulması için optimize edilmesi gerekmektedir. </li><li> Kültür ortamına colcemid (0.4 ug / ml) ilave edin ve 90 dakika metaph hücreleri yakalamak için inkübease. Farklı hücre tipleri kullanıldığında, deneysel olarak uygun metafaz tutuklama colcemid ve maruz kalma süresi (60, 90 ve 120 dakika) optimal konsantrasyonunu belirlemek. </li><li> Yıkama hücreleri, hücreler 3-5 mL% 0.25 tripsin solüsyonu eklenip hücreleri ayırmak için 5 dakika boyunca inkübe 1X Dulbecco PBS (DPBS), tripsinize 10 ml 2x. % 10 FBS ihtiva eden ortamın eşit miktarda tripsin inaktive. </li><li> , 4 ° C&#39;de 1000 x g&#39;de 2 dakika süre ile hücreler santrifüj hücre topağından orta aspire ve DPBS ile yıkama hücreleri. hücrelerin yeniden askıya DPBS 200 ul bırakarak aspire tüm DPBS. Sağlamak hücreler iyice karıştırılır ve kümeleri dağılmış olduğu. mix ve kümeleri dağıtmak ve vorteks önlemek için titrek ve nazik pipetleme kullanın. </li><li> Hipotonik çözelti 5 ml (yani, 75 mM KCI) yatay olarak 15 ml tüp dönerken 37 ° C&#39;de damla damla önceden ısıtılmış ve 20 dakika boyunca 37 ° C&#39;de inkübe edin. Malzeme ve Reagen Tablosu görünelde edilir ve hipotonik bir çözüm nasıl yapılacağı hakkında bilgi almak için ts. </li><li> Her yıkamadan sonra hücrelerin yeniden askıya hipotonik solüsyon yaklaşık 200 ul bırakarak 2.5 3x - 5 4 ° C&#39;de dakika ve yineleme için 120 xg&#39;de Santrifüj hücreleri 2.4 adımları. 3 yıkar sonunda, pelet gözle görülür beyaz ve şişmiş olduğundan emin olun. </li><li> Carnoy Sabitleme çözeltisi 200 ul pelet yeniden askıya artı 1: Carnoy Sabitleme çözeltisi içinde 8, 1:16 seyreltme: 2, 1: 4, 1. üzerinde yaklaşık 1 cm bir kuru, temiz slayt üzerine her seyreltme 10 ul damla ve hemen 30 saniye süreyle kaynar su sıcak buhara yayılmış serbest tarafını ortaya çıkarmak. Carnoy Sabitleme çözüm yapmak için nasıl Malzeme ve bilgi için Reaktifler Tablo bakınız. </li><li> 0.1 ug / ile, oda sıcaklığında, leke yayılır Kuru mi Hoechst-33342 Coplin kavanoza 15-20 dakika boyunca daldırma ile ve yıkama DPBS ile 3 kez. Hoechst-33342 çözüm yapmak için nasıl Malzeme ve bilgi için Reaktifler Tablo bakınız. </li> &lt;li&gt; Görünüm 40X büyütmede floresan / faz-kontrast mikroskop yayılır. Yayılma hazırlık optimize sonra, formalar Hoechst-33342 ile boyanmış olması gerekmez. Görünüm Sonuçlar bölümünde belirtildiği gibi yayılmış kalite ve ayırma belirlemek için 10X büyütmede faz-kontrast mikroskop yayılır (Şekil 3). </li><li> Seçip sürgünün karşı tarafında bir elmas noktası Marker iyi yayılır daire (örneğin, yayılabilir içermeyen tarafı). </li><li> Mağaza bir aya kadar -20 ° C&#39;de yayılır. neme maruz kalmaktan kaçının. </li></ol> Yerinde Hibridizasyon 3. Floresan (FISH) <ol><li> Yayılır, stabilize edici ve dehidre Not: -20 ° C&#39;de muhafaza edildiğinde dengeye metafaz kromozom, oda sıcaklığına kadar yayılır. elde etmek ve reaktifler yapmak için nasıl Malzeme ve bilgi için Reaktifler Tablo bakınız. <ol><li> Inkübe metafaz kromozom 200 ul RNaz A ile yayılır37 ° C&#39;de 1 saat. </li><li> Yıkama her biri 10 mm HCI çözeltisi ile durulama, ardından 5 dakika boyunca iki kez 2 x SSC tamponu-slaytlar. </li><li> Deiyonize H2O ile yıkayın ve her biri 5 dakika için 2X-SSC tamponu ile iki kez yıkanır, 37 ° C&#39;de 10 dakika süre ile% 1 pepsin ile yayılır inkübe edin. </li><li> 10 dakika boyunca% 4 paraformaldehit ile yayılır inkübe ve her biri 5 dakika iki kez 2 x SSC tamponu içinde yıkayın. </li><li> % 70,% 80 ve% 95 etanol: etanol seri 2 dakika süreyle inkübe edilerek yayılır dihidrat. </li><li> Hava kuru slaytlar. </li></ol></li><li> Melezleme L1 -etiketli retrotransposition probları ile yayılır (yani, sneo) DİKKAT: Doğrudan etiketli problar için, her zaman ışıktan uzak tutun. elde etmek ve reaktifler yapmak için nasıl Malzeme ve bilgi için Reaktifler Tablo bakınız. <ol><li> 10 dakika süre ile 72 ° C&#39;de hibridizasyon tamponuna sneo 30 ng, ısıtılır ve oda sıcaklığında 2 dakika boyunca soğutulur. </li><li> e sneo prob çözeltisi 30 ul ekleach yaymak, lamel ile kaplayın ve kauçuk çimento ile kenarları mühür. hiçbir kabarcık oluşumunu sağlamak. </li><li> yavaş yavaş 37 ° C&#39;ye kadar sıcaklık düşüşü ve 37 ° C de karanlık bir nemlendirilmiş oda içinde bir gece boyunca inkübe bir sıcaklıkta bir blok üzerinde 5 dakika boyunca 72 ° C&#39;de slayt ısıtın. </li></ol></li><li> Yıkama ve Görüntüleme (veya İkincil Antikor ilavesi) DİKKAT: Doğrudan etiketli problar için, her zaman ışıktan uzak tutun. NOT: Malzeme ve nasıl hazırlanacağı konusunda bilgi almak için Reaktifler Tablo bakınız. tüm kromozom yayılmasını karşılamak için yeterli hacimde kullanılması tavsiye edilir. lamel eklendiğinde fazla hacim kaybolur unutmayın. <ol><li> lamelleri kaldırmak için 2x SSC tamponu slaytlar daldırın. </li><li> 5 dakika boyunca 45 ° C&#39;de 2x SSC tamponu-batırılarak slaytlar yıkayın. </li><li> 5 dakika sonra 2x 45 ° C&#39;de yıkama tamponu içine daldırma ile slaytlar yıkayın. </li><li> 10 dakika boyunca 45 ° C&#39;de 0.1X SSC tamponu içine daldırma ile slaytlar yıkayın. </li><li>10 dakika boyunca 45 ° C &#39;de 2X SSC tamponu içine daldırma ile slaytlar yıkayın. Not: Talep bir su banyosu içinde önerilen tamponu ihtiva eden bir Coplin Kavanoz, 45 ° C&#39;ye kadar sıcaklık ayarlanır. </li><li> Soğuk oda sıcaklığına kadar slaytlar ve algılama tampon slaytlar dengeye. </li><li> direkt etiketli problar için, 3.4.10 adıma geçin. </li><li> Dolaylı etiketli problar için, 20-30 dakika süreyle ve tampon engelleme blok DPBS 3x yıkayın. </li><li> 1 saat boyunca (blokaj tamponu örneğin, 5 ug / ml streptavidin-FITC veya αCY3) ikincil antikor, 50 ul inkübe edin. </li><li> iki kez 5 dakika süreyle 2x SSC slaytlar yıkayın. </li><li> 10 dakika süre ile Hoechst-33342 solüsyonuna (0.1 ug / ml) ile karşıt. NOT: Bu boyama prob ile eş-lokalizasyonu için kromozom leke yapılır. </li><li> , Montaj orta bir damla ekleyin, DPBS 3x yıkayın lamel yerleştirin ve tırnak cilası ile kenarları mühür. </li><li> 40X ma floresan mikroskop kullanılarak L1 retrotransposition analizgnification. </li></ol></li></ol>

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L., 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=Epigenetic+silencing+of+engineered+L1+retrotransposition+events+in+human+embryonic+carcinoma+cells.">Epigenetic silencing of engineered L1 retrotransposition events in human embryonic carcinoma cells.</a> Nature. 466 (7307), 769-773 (2010).</li><li>Rodic, N., 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=Retrotransposon+insertions+in+the+clonal+evolution+of+pancreatic+ductual+adenocarcinoma.">Retrotransposon insertions in the clonal evolution of pancreatic ductual adenocarcinoma.</a> Nat Med. 21 (9), (2015).</li></ol>

Yazarlar potansiyel rakip çıkarları beyan ederim.

Böyle tüm genom dizileme, ters PCR ve güney blot olarak metodolojileri L1 retrotransposition incelemek için istihdam edilmiştir. Bu metodolojiler L1 eklemeleri genomları içinde meydana nerede yerini son derece değerli olmasına rağmen, hepsi için bir karıştırıcı zorluk dizileri yeniden birleştirmek için-siliko programlama için ihtiyaçtır. Burada açıklanan BALIK yöntemi, özellikle kültür hücrelerinde ektopik L1 retrotransposition analizleri gerektiren çalı?...

İnsan Uzun Interspersed Nükleer Element-1 (Hat-1 veya L1) retrotransposition mekanizmasını bir geçiş genomu içinde yayılır &quot;kopya ve yapıştır&quot; özerk mobil unsurdur. Tipik bir insan L1 ~ 6 kb uzunluğundadır ve bir promoter olarak hizmet veren bir 5&#39;UTR (çevrilmemiş bölgesinin) oluşur, iki açık okuma çerçevesi (ORF): L1 -ORF1 L1 -ORF2 ve polyA bir 3&#39;UTR . bobin bobin alanı, bir RNA tanıma motif ve C-terminal sahası, L1 -ORF2 proteini endonükleaz sahipken, transkriptaz ve sistin zengin alanları 1,2,3,4,5 tersine: yükleme L1 -ORF1 proteini üç farklı etki vardır. L1 -ORF2 retrotransposition 1,2,6 için gerekli iki proteinler ile, enzimatik aktiviteleri sağladığına; L1 -ORF1, nükleik asit şaperon aktivitelerini sergiler. L1 retrotransposition bir döngü L1 5&#39;UTR transkripsiyon ile başlar </em&gt; RNA polimeraz II, translokasyon sitoplazmaya ve çeviri tarafından bicistronic mRNA. Sitoplazma L1 -ORF1 sergiler, ya diğer RNA paketleri kendi RNA paketleri sis bağlayıcı eksojen veya trans bağlayıcı eksojen (örneğin, sinüs / SVAS / sözde genlerin) L1 -ORF2p 7 olan bir ribonükleoprotein parçacık (RNP) oluşturmak için, 8. Bu ana ters transkriptaz tarafından kullanılan da gruptur, 9 ve 3 &#39;ucundan DNA sentez RNA ters - RNP L1 -ORF2p çentik genomik DNA (gDNA) arasında endonükleaz aktivitesi, OH ortaya çıkarmak için çekirdek içine. Ters sentezi sırasında, DNA&#39;nın ikinci şerit imzası L1 ekleme dizileri (örneğin, TTTTAA) olarak adlandırılan hedef site duplikasyonları (TSD) 9,10 oluşturmak için doldurulur sendeleyerek kesmeleri oluşturmak için orijinal nick sitesinden 7-20 bp nicked edilir. Bu işlem, hedef ana ters transkripsiyon (TPRT) olarak bilinir ve inserti neden olduğueklenen dizinin her iki ucunda TSDs L1 / diğer DNA&#39;lar tam ya da tepe bölümü kesik kopya ile. L1 retrotransposition aracılığıyla da aracılık ettiği gösterilmiştir homolog olmayan uç birleştirme bazı hücre tiplerinde 11 TPRT benzeri. Çalışmalarımızda kullanılan L1 retrotransposition vektör epizomal olmayan ve etiketli L1 -ORF1 ve 2p Birleştirilen CMV L1-5&#39;UTR promoterler tarafından tahrik (şekil 1) 12 oluşur. Bu yapının önceki versiyonları maya ve insan hücre kültürleri 13,14,15 kullanıldığı çalışmalarda tarif edilmiştir. 3 &#39;ucu yapıştırma ve entegrasyon sonrasında neomisin ekspresyonunu tahrik etmek için ters yönde yerleştirilmiş olan 5&#39; ve 3 &#39;yer alan iki ayrı CMV promoterler, vektörün sona erer. 3 &#39;ucunda retrotransposition göstergesi kaseti L1 -ORFs bir neomisin geni yerleştirilmiş antisens oluşur ve topak iki parçaya ayrılması ile aktif olmayan haleeklenmiş verici (SD) ve eklenmiş alıcı (SA) siteleri (Şekil 1) introna, uygun olarak. Bir kromozom içine entegrasyon üzerine, L1 bir bicistronic mRNA ve inaktif neomisin mRNA oluşan bir mRNA üretmek için ortak promotör transkripsiyonu. RNA işlenmesi sırasında, globin intron tamamen işlevsel bir neomisin geni geri neomisin genin dışında birleştirilir. Hibrid mRNA cis bir RNP içine paketlenmiş ve TPRT kullanılarak tam uzunluklu ya da kesilmiş ya da sokulmasını genomuna entegre edilir çekirdeğe transloke edilmiştir. Burada tek çekirdek düzeyinde L1 -retrotransposiition desen ve yerleştirme oranlarını izlemek için özel olarak eklenmiş neomisin geni (sneo) yönelik problar ile in situ hibridizasyon (FISH) floresan kullanan bir metodoloji tarif eder. verimlilik ve algılama özgüllüğü det yetkili retrotransposition ve beceriksiz yapıları ve problar kullanılarak teyit edildiEKT sneo veya intron kavşağı 16 globin neomisin ve. Bu metodoloji, çoklu eklemeler, koloni direnci ve olumlu klon genişleme olarak hücre kültürü temelli retrotransposition deneyleri, eksikliklerin bazıları oluşturmaktadır.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Labeling Probes</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Go Tag DNA polymerase</td>
			<td>Promega</td>
			<td>M3178</td>
			<td></td>
		</tr>
		<tr>
			<td>GO Tag 10X colorless buffer</td>
			<td>Promega</td>
			<td>M3178</td>
			<td></td>
		</tr>
		<tr>
			<td>Individual dNTP</td>
			<td>Sigma</td>
			<td>DNTP10</td>
			<td>Adjust the concentration of dATP, dGTP, dCTP to 2mM and dTTP to 1.5mM&#160; in nuclease free water.</td>
		</tr>
		<tr>
			<td>&#160;dUTP-16-Biotin (0.5mM)</td>
			<td>Roche</td>
			<td>11093070910</td>
			<td></td>
		</tr>
		<tr>
			<td>dUTP-FITC (0.5mM)</td>
			<td>Thermo Scientific</td>
			<td>R0101</td>
			<td></td>
		</tr>
		<tr>
			<td>dUTP-CY3 (0.5mM)</td>
			<td>Sigma</td>
			<td>GEPA53022</td>
			<td></td>
		</tr>
		<tr>
			<td>MIRUS FISH Labeling Kit</td>
			<td>MIRUS</td>
			<td>MIR3625</td>
			<td></td>
		</tr>
		<tr>
			<td>MIRUS FISH Labeling Kit</td>
			<td>MIRUS</td>
			<td>MIR3225</td>
			<td></td>
		</tr>
		<tr>
			<td>NucleoSpin PCR Clean-Up kit&#160;</td>
			<td>Qiagen</td>
			<td>1410/0030</td>
			<td>Any PCR clean reagent can be used in place of NucleoSpin PCR Clean Up Kit</td>
		</tr>
		<tr>
			<td>PCR Machine</td>
			<td></td>
			<td></td>
			<td>Any Thermocycler machine can be used to amplify the label product.</td>
		</tr>
		<tr>
			<td>Agarose</td>
			<td>Sigma</td>
			<td>A9539</td>
			<td></td>
		</tr>
		<tr>
			<td>Name</td>
			<td>Company</td>
			<td>Catalog Number</td>
			<td>Comments</td>
		</tr>
		<tr>
			<td>Preparing chromosome Spreads.</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>&#160;&#160;&#160;&#160; Colcemid&#160;</td>
			<td>Life Technologies&#160;</td>
			<td>15212-012</td>
			<td>Add Colcemid directly to growth media&#160; to a final concentration of 0.4 &#181;g/mL</td>
		</tr>
		<tr>
			<td>1M KCl</td>
			<td>Sigma</td>
			<td>P9541</td>
			<td>Dilute 1M KCl solution to 75 mM solution to make Hypotonic Solution</td>
		</tr>
		<tr>
			<td>Carnoy Fixative Solution</td>
			<td></td>
			<td></td>
			<td>Mix 3 volumes of methanol and 1 volume of acetic acid to make Carnoy Fixative Solution. Make Fresh everytime.</td>
		</tr>
		<tr>
			<td>Methanol</td>
			<td>Sigma</td>
			<td>322415</td>
			<td></td>
		</tr>
		<tr>
			<td>Acetic acid</td>
			<td>Sigma</td>
			<td>320099</td>
			<td></td>
		</tr>
		<tr>
			<td>Hoechst-33342</td>
			<td>Thermo Scientific</td>
			<td>62249</td>
			<td>Dissolve Hoechst-33342 in PBS to final concentration of 1 mg/mL.</td>
		</tr>
		<tr>
			<td>Diamond Point Marker</td>
			<td>Thermo Scientific</td>
			<td>750</td>
			<td></td>
		</tr>
		<tr>
			<td>Frosted Slides</td>
			<td>Thermo Scientific</td>
			<td>2951-001</td>
			<td></td>
		</tr>
		<tr>
			<td>Trypsin-EDTA (0.25%)</td>
			<td>Life Technologies&#160;</td>
			<td>R001100</td>
			<td>To detech cells, incubate cell in Trypsin for 5 mins and inactive with equal volume of complete media</td>
		</tr>
		<tr>
			<td>Cover slides&#160;</td>
			<td>VWR</td>
			<td>48366067</td>
			<td></td>
		</tr>
		<tr>
			<td>Coplin Jars</td>
			<td>Thermo Scientific</td>
			<td>107</td>
			<td></td>
		</tr>
		<tr>
			<td>&#160;Heat Block</td>
			<td></td>
			<td></td>
			<td>Any heat block can be used for this purpose, though blocks fitted for heating slides are recommended.</td>
		</tr>
		<tr>
			<td>&#160;Beaker (600ml)</td>
			<td>Sigma</td>
			<td>CLS1003600</td>
			<td>Fill the beaker with water, heat to boil, use the hot steam to burst chromosomes.</td>
		</tr>
		<tr>
			<td>Nikon Microscope</td>
			<td>Nikon</td>
			<td>125690</td>
			<td>Any microscope can be used to look at spread quality.</td>
		</tr>
		<tr>
			<td>Name</td>
			<td>Company</td>
			<td>Catalog Number</td>
			<td>Comments</td>
		</tr>
		<tr>
			<td>Reagents and Materials for FISH</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Trisodium citrate</td>
			<td>Sigma</td>
			<td>S1804</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium Chroride</td>
			<td>Sigma</td>
			<td>S3014</td>
			<td></td>
		</tr>
		<tr>
			<td>Formamide</td>
			<td>Sigma</td>
			<td>F9037</td>
			<td></td>
		</tr>
		<tr>
			<td>Tween-20</td>
			<td>Sigma</td>
			<td>F1379</td>
			<td></td>
		</tr>
		<tr>
			<td>Detran Sulfate</td>
			<td>Sigma</td>
			<td>D8906</td>
			<td></td>
		</tr>
		<tr>
			<td>SDS</td>
			<td>Sigma</td>
			<td>L3771</td>
			<td></td>
		</tr>
		<tr>
			<td>Salmon Sperm DNA</td>
			<td>Life Technologies&#160;</td>
			<td>15632-011</td>
			<td></td>
		</tr>
		<tr>
			<td>Bovine Serum Albumin (BSA)</td>
			<td>Sigma</td>
			<td>A8531</td>
			<td></td>
		</tr>
		<tr>
			<td>HCl (N)</td>
			<td>Sigma</td>
			<td>38283</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethyl Alcohol</td>
			<td>Sigma</td>
			<td>459844</td>
			<td></td>
		</tr>
		<tr>
			<td>Methanol</td>
			<td>Sigma</td>
			<td>322415</td>
			<td></td>
		</tr>
		<tr>
			<td>DPBS</td>
			<td>Life Technologies&#160;</td>
			<td>14190-250</td>
			<td></td>
		</tr>
		<tr>
			<td>NaOH</td>
			<td>Sigma</td>
			<td>S8045</td>
			<td></td>
		</tr>
		<tr>
			<td>Rnase A</td>
			<td>Sigma</td>
			<td>R4642</td>
			<td></td>
		</tr>
		<tr>
			<td>Pepsin</td>
			<td>Sigma</td>
			<td>P6887</td>
			<td></td>
		</tr>
		<tr>
			<td>Paraformaldehyde (PFA)</td>
			<td>Sigma</td>
			<td>P6148</td>
			<td></td>
		</tr>
		<tr>
			<td>Hoechst-33342</td>
			<td>Thermo Scientific</td>
			<td>62249</td>
			<td>Dissolve Hoechst-33342 in PBS to final concentration of 1 mg/mL.</td>
		</tr>
		<tr>
			<td>Rubber Cement/Cytobond Sealant&#160;</td>
			<td></td>
			<td>2020-00-1</td>
			<td></td>
		</tr>
		<tr>
			<td>Seven Coplin Jars</td>
			<td>Thermo Scientific</td>
			<td>107</td>
			<td></td>
		</tr>
		<tr>
			<td>&#160; Dark Humidified chamber</td>
			<td>Sigma</td>
			<td>CLS2551</td>
			<td></td>
		</tr>
		<tr>
			<td>Cover slides&#160;</td>
			<td>VWR</td>
			<td>48366067</td>
			<td></td>
		</tr>
		<tr>
			<td>Dry Digital Heat Block</td>
			<td>VWR</td>
			<td>13259</td>
			<td></td>
		</tr>
		<tr>
			<td>&#160;Fluorescence Microscope</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>20X Saline-Sodium Citrate (20X SSC)</td>
			<td></td>
			<td></td>
			<td>Combine 175 g of NaCl, and 88.2 g of trisodium citrate with 800 mL of molecular grade H2O. Stir while adjusting to pH 7. Once the all salts dissolve, adjust the volume to 1 L and filter through 0.22 &#181;m Filter paper. Store at 4 &#176;C.</td>
		</tr>
		<tr>
			<td>&#160;1mg/mL of Rnase A</td>
			<td></td>
			<td></td>
			<td>Dilute 20X SSC buffer to 2X SSC buffer. Dissolve RNase A in 2X SSC buffer to a final concentration of 1 mg/mL. Make fresh solution every time.</td>
		</tr>
		<tr>
			<td>1% Pepsin</td>
			<td></td>
			<td></td>
			<td>Dissolve&#160; pepsin (W/V) in 10 mM HCl to a final concentration of 1 % solution. Make fresh every time.</td>
		</tr>
		<tr>
			<td>4% Paraformaldehyde (4% PFA)</td>
			<td></td>
			<td></td>
			<td>Weigh 4.0 g of PFA in fume hood, add 50 mL of 1xPBS, heat to 60 &#176;C while stirring and adjust the pH with drops of NaOH until all PFA dissolves and the solution becomes clear. Adjust the volume to 100 mL, filter through 0.22 &#181;m Filter paper and store 5 mL aliquots at -20 &#176;C. Thaw aliquot of PFA at 37 &#176;C for 10-15 min for subsequent uses.&#160; Adjust filter size depending on amount of paraformaldehyde.</td>
		</tr>
		<tr>
			<td>Wash Buffer</td>
			<td></td>
			<td></td>
			<td>Combine 100 mL of Formamide (20%) with 2.5 mL of 20X SSC, adjust to pH 7 with 1.0 M HCl and bring the volume to 500 mL with molecular grade H2O.</td>
		</tr>
		<tr>
			<td>Hybridization Buffer</td>
			<td></td>
			<td></td>
			<td>Combine 50% formamide, 10% dextran sulfate, 0.1% SDS, and 300 ng/mL Salmon Sperm DNA in 2X SSC buffer.&#160; Amount of Formamide determine how focused chromatids are, titrate the amount&#160;</td>
		</tr>
		<tr>
			<td>Detection Buffer</td>
			<td></td>
			<td></td>
			<td>Dilute 20X SSC buffer to 4X and add 0.2% Tween-20 to make detection buffer.</td>
		</tr>
		<tr>
			<td>Blocking Buffer</td>
			<td></td>
			<td></td>
			<td>Combine 5% bovine serum albumin (BSA) with 0.2% Tween-20 in 4X SSC buffer.</td>
		</tr>
		<tr>
			<td>Dehydrating Solution</td>
			<td></td>
			<td></td>
			<td>Make 70%, 80%, and 95% ethanol solutions.</td>
		</tr>
	</tbody>
</table>

analysis of line-1 retrotransposition at the single nucleus level

Long interspersed nuclear element-1 (Line-1 or L1) accounts for approximately 17% of the DNA present in the human genome. While the majority of L1s are inactive due to 5' truncations, ~80-100 of these elements remain retrotransposition competent and propagate to different locations throughout the genome via RNA intermediates. While older L1s are believed to target AT rich regions of the genome, the chromosomal targets of newer, more active L1s remain poorly defined. Here we describe fluorescence in situ hybridization (FISH) methodology that can be used to track patterns of L1 insertion and rates of ectopic L1 incorporation at the single nucleus level. In these experiments, fluorescein isothiocyanate/cyanine-3 (FITC/CY3) labeled neomycin probes were employed to track L1 retrotransposition in vitro in HepG2 cells stably expressing ectopic L1. This methodology prevents errors in the estimation of rates of retrotransposition posed by toxicity and account for the occurrence of multiple insertions into a single nucleus.

L1 retrotransposition vektörünün şematik bir diyagramıdır, Şekil 1 &#39;de sunulmuştur. Vektörü sens yönlenmede bir globin intronu ile kesilmiş ve SD ve SA siteleri tarafından sandviç L1 ORF antisens yönlenmede bir neomisin geni içerir. Kararlı biçimde bir kromozomda entegre olduğunda, L1 mRNA Birleştirilen CMV ve L1-5&#39;UTR promotörünün (Şekil 1) transkripsiyonu. RNA işlenmesi sırasında, globin int...

Watch this Scientific Journal Video about Analysis of LINE-1 Retrotransposition at the Single Nucleus Level at JoVE.com

Analysis of LINE-1 Retrotransposition at the Single Nucleus Level

Tek Çekirdek Düzeyde HAT-1 Retrotransposition Analizi

Burada stabil sentetik LINE-1 ifade eden HepG2 hücre hatlarının kromozom yayılır tek çekirdek düzeyinde HAT-1 retrotransposition izlemek için FISH metodolojisini kullanır.

Long interspersed nuclear element-1 (Line-1 or L1) accounts for approximately 17% of the DNA present in the human genome. While the majority of L1s are ...

analysis-of-line-1-retrotransposition-at-the-single-nucleus-level

Research

JoVE Journal

Biology

8.3K Görüntüleme.  University of Arizona College of Medicine.  Burada stabil sentetik LINE-1 ifade eden HepG2 hücre hatlarının kromozom yayılır tek çekirdek düzeyinde HAT-1 retrotransposition izlemek için FISH metodolojisini kullanır. 

Video: Analysis of LINE-1 Retrotransposition at the Single Nucleus Level

Method for Measurement of Viral Fusion Kinetics at the Single Particle Level

Membrane fusion is an essential step during entry of enveloped viruses into cells. Conventional fusion assays typically report on a large number of fusion events, making it difficult to quantitatively analyze the sequence of the molecular steps involved. We have developed an in vitro, two-color fluorescence assay to monitor kinetics of single virus particles fusing with a target bilayer on an essentially fluid support.
Influenza viral particles are incubated with a green lipophilic fluorophore to stain the membrane and a red hydrophilic fluorophore to stain the viral interior. We deposit a ganglioside-containing lipid bilayer on the dextran-functionilized glass surface of a flow cell, incubate the viral particles on the planar bilayer and image the fluorescence of a 100 x 100 &mu;m2 area, containing several hundreds of particles, on a CCD camera. By imaging both the red and green fluorescence, we can simultaneously monitor the behavior of the membrane dye (green) and the aqueous content (red) of the particles.
Upon lowering the pH to a value below the fusion pH, the particles will fuse with the membrane. Hemifusion, the merging of the outer leaflet of the viral membrane with the outer leaflet of the target membrane, will be visible as a sudden change in the green fluorescence of a particle. Upon the subsequent fusion of the two remaining distal leaflets a pore will be formed and the red-emitting fluorophore in the viral particle will be released under the target membrane. This event will give rise to a decrease of the red fluorescence of individual particles. Finally, the integrated fluorescence from a pH-sensitive fluorophore that is embedded in the target membrane reports on the exact time of the pH drop.
From the three fluorescence-time traces, all the important events (pH drop, lipid mixing upon hemifusion, content mixing upon pore formation) can now be extracted in a straightforward manner and for every particle individually. By collecting the elapsed times for the various transitions for many individual particles in histograms, we can determine the lifetimes of the corresponding intermediates. Even hidden intermediates that do not have a direct fluorescent observable can be visualized directly from these histograms.

We present an in vitro, two-color fluorescence assay to visualize the fusion of single virus particles with a fluid target bilayer. By labeling viral particles with fluorophores that differentially stain the viral membrane and its interior, we are able to monitor the kinetics of hemifusion and pore formation.

Tek Parçacık Düzeyinde Viral Fusion Kinetik Ölçüm yöntemi

Membrane fusion is an essential step during entry of enveloped viruses into cells. Conventional fusion assays typically report on a large number of fusion ...

Biyoloji

Direct Analysis of Single Cells by Mass Spectrometry at Atmospheric Pressure

Analysis of biochemicals in single cells is important for understanding cell metabolism, cell cycle, adaptation, disease states, etc. Even the same cell types exhibit heterogeneous biochemical makeup depending on their physiological conditions and interactions with the environment. Conventional methods of mass spectrometry (MS) used for the analysis of biomolecules in single cells rely on extensive sample preparation. Removing the cells from their natural environment and extensive sample processing could lead to changes in the cellular composition. Ambient ionization methods enable the analysis of samples in their native environment and without extensive sample preparation.1 The techniques based on the mid infrared (mid-IR) laser ablation of biological materials at 2.94 &mu;m wavelength utilize the sudden excitation of water that results in phase explosion.2 Ambient ionization techniques based on mid-IR laser radiation, such as laser ablation electrospray ionization (LAESI) and atmospheric pressure infrared matrix-assisted laser desorption ionization (AP IR-MALDI), have successfully demonstrated the ability to directly analyze water-rich tissues and biofluids at atmospheric pressure.3-11 In LAESI the mid-IR laser ablation plume that mostly consists of neutral particulate matter from the sample coalesces with highly charged electrospray droplets to produce ions. Recently, mid-IR ablation of single cells was performed by delivering the mid-IR radiation through an etched fiber. The plume generated from this ablation was postionized by an electrospray enabling the analysis of diverse metabolites in single cells by LAESI-MS.12 This article describes the detailed protocol for single cell analysis using LAESI-MS. The presented video demonstrates the analysis of a single epidermal cell from the skin of an Allium cepa bulb. The schematic of the system is shown in Figure 1. A representative example of single cell ablation and a LAESI mass spectrum from the cell are provided in Figure 2.

Single cell analysis is performed by mass spectrometry on plant and animal cells at atmospheric pressure by using a sharpened optical fiber to sample the cells for laser ablation electrospray ionization (LAESI) mass spectrometry.

Doğrudan Atmosferik Basınç Kütle Spektrometresi Tek Hücre Analizi

Analysis of biochemicals in single cells is important for understanding cell metabolism, cell cycle, adaptation, disease states, etc. Even the same cell ...

Studying Proteolysis of Cyclin B at the Single Cell Level in Whole Cell Populations

Equal distribution of chromosomes between the two daughter cells during cell division is a prerequisite for guaranteeing genetic stability 1. Inaccuracies during chromosome separation are a hallmark of malignancy and associated with progressive disease 2-4. The spindle assembly checkpoint (SAC) is a mitotic surveillance mechanism that holds back cells at metaphase until every single chromosome has established a stable bipolar attachment to the mitotic spindle1. The SAC exerts its function by interference with the activating APC/C subunit Cdc20 to block proteolysis of securin and cyclin B and thus chromosome separation and mitotic exit. Improper attachment of chromosomes prevents silencing of SAC signaling and causes continued inhibition of APC/CCdc20 until the problem is solved to avoid chromosome missegregation, aneuploidy and malignant growths1.
Most studies that addressed the influence of improper chromosomal attachment on APC/C-dependent proteolysis took advantage of spindle disruption using depolymerizing or microtubule-stabilizing drugs to interfere with chromosomal attachment to microtubules. Since interference with microtubule kinetics can affect the transport and localization of critical regulators, these procedures bear a risk of inducing artificial effects 5.
To study how the SAC interferes with APC/C-dependent proteolysis of cyclin B during mitosis in unperturbed cell populations, we established a histone H2-GFP-based system which allowed the simultaneous monitoring of metaphase alignment of mitotic chromosomes and proteolysis of cyclin B 6.
To depict proteolytic profiles, we generated a chimeric cyclin B reporter molecule with a C-terminal SNAP moiety 6 (Figure 1). In a self-labeling reaction, the SNAP-moiety is able to form covalent bonds with alkylguanine-carriers (SNAP substrate) 7,8 (Figure 1). SNAP substrate molecules are readily available and carry a broad spectrum of different fluorochromes. Chimeric cyclin B-SNAP molecules become labeled upon addition of the membrane-permeable SNAP substrate to the growth medium 7 (Figure 1). Following the labeling reaction, the cyclin B-SNAP fluorescence intensity drops in a pulse-chase reaction-like manner and fluorescence intensities reflect levels of cyclin B degradation 6 (Figure 1). Our system facilitates the monitoring of mitotic APC/C-dependent proteolysis in large numbers of cells (or several cell populations) in parallel. Thereby, the system may be a valuable tool to identify agents/small molecules that are able to interfere with proteolytic activity at the metaphase to anaphase transition. Moreover, as synthesis of cyclin B during mitosis has recently been suggested as an important mechanism in fostering a mitotic block in mice and humans by keeping cyclin B expression levels stable 9,10, this system enabled us to analyze cyclin B proteolysis as one element of a balanced equilibrium 6.

Metaphase to anaphase transition is triggered through anaphase-promoting complex (APC/C)-dependent ubiquitination and subsequent destruction of cyclin B. Here, we established a system which, following pulse-chase labeling, allows monitoring cyclin B proteolysis in entire cell populations and facilitates the detection of interference by the mitotic checkpoint.

Tüm Cep Populasyonlarının Tek Hücre Düzeyinde Siklin B Proteoliz incelenmesi

Equal distribution of chromosomes between the two daughter cells during cell division is a prerequisite for guaranteeing genetic stability 1. Inaccuracies ...

Efficient Agroinfiltration of Plants for High-level Transient Expression of Recombinant Proteins

Mammalian cell culture is the major platform for commercial production of human vaccines and therapeutic proteins. However, it cannot meet the increasing worldwide demand for pharmaceuticals due to its limited scalability and high cost. Plants have shown to be one of the most promising alternative pharmaceutical production platforms that are robust, scalable, low-cost and safe. The recent development of virus-based vectors has allowed rapid and high-level transient expression of recombinant proteins in plants. To further optimize the utility of the transient expression system, we demonstrate a simple, efficient and scalable methodology to introduce target-gene containing Agrobacterium into plant tissue in this study. Our results indicate that agroinfiltration with both syringe and vacuum methods have resulted in the efficient introduction of Agrobacterium into leaves and robust production of two fluorescent proteins; GFP and DsRed. Furthermore, we demonstrate the unique advantages offered by both methods. Syringe infiltration is simple and does not need expensive equipment. It also allows the flexibility to either infiltrate the entire leave with one target gene, or to introduce genes of multiple targets on one leaf. Thus, it can be used for laboratory scale expression of recombinant proteins as well as for comparing different proteins or vectors for yield or expression kinetics. The simplicity of syringe infiltration also suggests its utility in high school and college education for the subject of biotechnology. In contrast, vacuum infiltration is more robust and can be scaled-up for commercial manufacture of pharmaceutical proteins. It also offers the advantage of being able to agroinfiltrate plant species that are not amenable for syringe infiltration such as lettuce and Arabidopsis. Overall, the combination of syringe and vacuum agroinfiltration provides researchers and educators a simple, efficient, and robust methodology for transient protein expression. It will greatly facilitate the development of pharmaceutical proteins and promote science education.

Plants offer a novel system for the production of pharmaceutical proteins on a commercial scale that is more scalable, cost-efficient and safe than current expression paradigms. In this study, we report a simple and convenient, yet scalable approach to introduce target-gene containing Agrobacterium tumefaciens into plants for protein transient expression.

Rekombinant Proteinlerin Yüksek-düzey Geçici İfade için Bitkiler Verimli Agroinfiltration

Mammalian cell culture is the major platform for commercial production of human vaccines and therapeutic proteins. However, it cannot meet the increasing ...

Analysis of Global RNA Synthesis at the Single Cell Level following Hypoxia

Hypoxia or lowering of the oxygen availability is involved in many physiological and pathological processes. At the molecular level, cells initiate a particular transcriptional program in order to mount an appropriate and coordinated cellular response. The cell possesses several oxygen sensor enzymes that require molecular oxygen as cofactor for their activity. These range from prolyl-hydroxylases to histone demethylases. The majority of studies analyzing cellular responses to hypoxia are based on cellular populations and average studies, and as such single cell analysis of hypoxic cells are seldom performed. Here we describe a method of analysis of global RNA synthesis at the single cell level in hypoxia by using Click-iT RNA imaging kits in an oxygen controlled workstation, followed by microscopy analysis and quantification.&nbsp; Using cancer cells exposed to hypoxia for different lengths of time, RNA is labeled and measured in each cell. This analysis allows the visualization of temporal and cell-to-cell changes in global RNA synthesis following hypoxic stress.

We describe a technique for analysis of global RNA synthesis in hypoxia using imaging. Click-chemistry labeling of RNA has not previously been performed under hypoxia and allows visualization of global RNA changes at the single cell level. This approach complements the existing averaged RNA techniques, allowing direct visualization of cell-to-cell changes in global RNA synthesis.

Ününüz Aşağıdaki Tek Hücre Düzeyinde Küresel RNA Sentezi Analizi

Hypoxia or lowering of the oxygen availability is involved in many physiological and pathological processes. At the molecular level, cells initiate a ...

CUBIC Protocol Visualizes Protein Expression at Single Cell Resolution in Whole Mount Skin Preparations

The skin is essential for our survival. The outer epidermal layer consists of the interfollicular epidermis, which is a stratified squamous epithelium covering most of our body, and epidermal appendages such as the hair follicles and sweat glands. The epidermis undergoes regeneration throughout life and in response to injury. This is enabled by K14-expressing basal epidermal stem/progenitor cell populations that are tightly regulated by multiple regulatory mechanisms active within the epidermis and between epidermis and dermis. This article describes a simple method to clarify full thickness mouse skin biopsies, and visualize K14 protein expression patterns, Ki67 labeled proliferating cells, Nile Red labeled sebocytes, and DAPI nuclear labeling at single cell resolution in 3D. This method enables accurate assessment and quantification of skin anatomy and pathology, and of abnormal epidermal phenotypes in genetically modified mouse lines. The CUBIC protocol is the best method available to date to investigate molecular and cellular interactions in full thickness skin biopsies at single cell resolution.

This report describes a CUBIC protocol to clarify full thickness mouse skin biopsies, and visualize protein expression patterns, proliferating cells, and sebocytes at the single cell resolution in 3D. This method enables accurate assessment of skin anatomy and pathology, and of abnormal epidermal phenotypes in genetically modified mouse lines.

KÜBİK Protokol Tüm Dağı Cilt Hazırlıkları Tek Hücre çözünürlükte Protein Anlatım Görseller

The skin is essential for our survival. The outer epidermal layer consists of the interfollicular epidermis, which is a stratified squamous epithelium ...

Analysis of Beta-cell Function Using Single-cell Resolution Calcium Imaging in Zebrafish Islets

Pancreatic beta-cells respond to increasing blood glucose concentrations by secreting the hormone insulin. The dysfunction of beta-cells leads to hyperglycemia and severe, life-threatening consequences. Understanding how the beta-cells operate under physiological conditions and what genetic and environmental factors might cause their dysfunction could lead to better treatment options for diabetic patients. The ability to measure calcium levels in beta-cells serves as an important indicator of beta-cell function, as the influx of calcium ions triggers insulin release. Here we describe a protocol for monitoring the glucose-stimulated calcium influx in zebrafish beta-cells by using GCaMP6s, a genetically encoded sensor of calcium. The method allows monitoring the intracellular calcium dynamics with single-cell resolution in ex vivo mounted islets. The glucose-responsiveness of beta-cells within the same islet can be captured simultaneously under different glucose concentrations, which suggests the presence of functional heterogeneity among zebrafish beta-cells. Furthermore, the technique provides high temporal and spatial resolution, which reveals the oscillatory nature of the calcium influx upon glucose stimulation. Our approach opens the doors to use the zebrafish as a model to investigate the contribution of genetic and environmental factors to beta-cell function and dysfunction.

Beta-cell functionality is important for blood-glucose homeostasis, which is evaluated at single-cell resolution using a genetically encoded reporter for calcium influx.

Zebra balığı adacıkları tek hücreli çözünürlük kalsiyum Imaging'i kullanma Beta hücre fonksiyonu Analizi

Pancreatic beta-cells respond to increasing blood glucose concentrations by secreting the hormone insulin. The dysfunction of beta-cells leads to ...

Visualizing the Interaction Between the Qdot-labeled Protein and Site-specifically Modified &#955; DNA at the Single Molecule Level

The fluorescence microscopy&#160;has made great contributions in dissecting the mechanisms of complex biological processes at the single molecule level. In single molecule assays for studying DNA-protein interactions, there are two important factors for consideration: the DNA substrate with enough length for easy observation and labeling a protein with a suitable fluorescent probe. 48.5 kb &#955; DNA is a good candidate for the DNA substrate. Quantum dots (Qdots), as a class of fluorescent probes, allow long-time observation (minutes to hours) and high-quality image acquisition. In this paper, we present a protocol to study DNA-protein interactions at the single-molecule level, which includes preparing a site-specifically modified &#955; DNA and labeling a target protein with streptavidin-coated Qdots. For a proof of concept, we choose ORC (origin recognition complex) in budding yeast as a protein of interest and visualize its interaction with an ARS (autonomously replicating sequence) using TIRFM. Compared with other fluorescent probes, Qdots have obvious advantages in single molecule studies due to its high stability against photobleaching, but it should be noted that this property limits its application in quantitative assays.

Here, we present a protocol to study DNA-protein interactions by total internal reflection fluorescence microscopy (TIRFM) using a site-specifically modified &#955; DNA substrate and a Quantum-dot labeled protein.

Qdot etiketli Protein ve Site-specifically tarihinde λ DNA molekülünü düzeyinde arasındaki etkileşimi görüntülenmesi

The fluorescence microscopy&#160;has made great contributions in dissecting the mechanisms of complex biological processes at the single molecule level. ...

Probing mRNA Kinetics in Space and Time in Escherichia coli using Two-Color Single-Molecule Fluorescence In Situ Hybridization

Single-molecule fluorescence in situ hybridization (smFISH) allows for counting the absolute number of mRNAs in individual cells. Here, we describe an application of smFISH to measure the rates of transcription and mRNA degradation in Escherichia coli. As smFISH is based on fixed cells, we perform smFISH at multiple time points during a time-course experiment, i.e., when cells are undergoing synchronized changes upon induction or repression of gene expression. At each time point, sub-regions of an mRNA are spectrally distinguished to probe transcription elongation and premature termination. The outcome of this protocol also allows for analyzing intracellular localization of mRNAs and heterogeneity in mRNA copy numbers among cells. Using this protocol many samples (~50) can be processed within 8 h, like the amount of time needed for just a few samples. We discuss how to apply this protocol to study the transcription and degradation kinetics of different mRNAs in bacterial cells.

Probing mRNA Kinetics in Space and Time in Escherichia coli using Two-Color Single-Molecule Fluorescence In Situ Hybridization

This protocol describes an application of single-molecule fluorescence in situ hybridization (smFISH) to measure the in vivo kinetics of mRNA synthesis and degradation.

Situ Hibridizasyonda İki Renkli Tek Moleküllü Floresan Kullanarak Escherichia coli'de Uzay ve Zamanda MRNA KinetikLerini Sondalama

Single-molecule fluorescence in situ hybridization (smFISH) allows for counting the absolute number of mRNAs in individual cells. Here, we describe an ...

Nuclei Isolation from Adult Mouse Kidney for Single-Nucleus RNA-Sequencing

The kidneys regulate diverse biological processes such as water, electrolyte, and acid-base homeostasis. Physiological functions of the kidney are executed by multiple cell types arranged in a complex architecture across the corticomedullary axis of the organ. Recent advances in single-cell transcriptomics have accelerated the understanding of cell type-specific gene expression in renal physiology and disease. However, enzyme-based tissue dissociation protocols, which are frequently utilized for single-cell RNA-sequencing (scRNA-seq), require mostly fresh (non-archived) tissue, introduce transcriptional stress responses, and favor the selection of abundant cell types of the kidney cortex resulting in an underrepresentation of cells of the medulla.
Here, we present a protocol that avoids these problems. The protocol is based on nuclei isolation at 4 &#176;C from frozen kidney tissue. Nuclei are isolated from a central piece of the mouse kidney comprised of the cortex, outer medulla, and inner medulla. This reduces the overrepresentation of cortical cells typical for whole-kidney samples for the benefit of medullary cells such that data will represent the entire corticomedullary axis at sufficient abundance. The protocol is simple, rapid, and adaptable and provides a step towards the standardization of single-nuclei transcriptomics in kidney research.

Here, we present a protocol to isolate high-quality nuclei from frozen mouse kidneys that improve the representation of medullary kidney cell types and avoids the gene expression artifacts from enzymatic tissue dissociation.