This study was financially supported by the Korean Ministry of Science, ICT and Future Planning (Intelligent Synthetic Biology Center program 2012M3A6A8054887). P. Kim was supported by a fellowship from the Catholic University of Korea (2015).

1. Ekipman Hazırlığı <ol><li> Bir kemostat küp (150-250 mi) ya da bir giriş noktası ihtiva eden bir bir Erlenmeyer şişesi (250 mi) ve bir çıkış portuna elde edin. silikon boru 10-100 ml / saat akış hızları için izin ile bağlantı noktalarını bağlayın. İsteğe bağlı olarak, bir hava deliği, bir hava çıkış ağzı, ve sıcaklık kontrollü su giriş ve çıkış bağlantı noktaları kullanımı. </li><li> ajitasyon ve ısı kontrolü sağlayan kemostat kavanoz için uygun olan bir cihaz elde edilir (veya bir döner çalkalama inkübatöründe kullanın). </li><li> kültür taze orta teslim ve toplamak için iki peristaltik pompa edinin. </li><li> orta çıkış deliği ve bir hava giriş ağzı ihtiva eden bir hazne kavanoz (10-20 L) elde edilir. </li><li> (L / S 13 boru Yani, ID, 0.8 mm, akış aralığı 0,06-36 ml / dak) seyrelme oranı için uygun silikon boru elde edilir. </li></ol> 2. Orta Hazırlama ve Sterilizasyon <ol><li> ilk Orta <ol><li> 0.3 gr glikoz, 0.08 g NH4 çözülürCI, 0.05 g NaCl, 0.75 g Na 2 HPO 4 · 2H 2, O, ve 0.3 g KH 2 PO 4 90 ml damıtılmış su, kemostat kavanoza (DW). </li><li> kelepçeler kullanılarak boru ile birlikte kemostat kavanoz mühür. havalandırma deliğini mühür yok. </li><li> 15 dakika boyunca 121 ° C&#39;de bir otoklav içinde kemostat kavanoz sterilize edin. Sterilizasyon sonrasında, oda sıcaklığında kemostat kavanoz saklayın. </li><li> Çözülür 0.02 gr MgSO 4 · 7H 2, O, 0.01 g CaCl2 ve 10 mi DW (A çözeltisi) içinde 0.1 mg tiamin. </li><li> bir şırınga ve bir önceden sterilize edilmiş şırınga filtresi (0.45 mikron gözenek filtresi) ile filtre solüsyonu için uygun değildir. </li><li> Bir kemostat kavanoza süzüntüler çözüm ekleyin. </li></ol></li><li> stres Orta <ol><li> 30 g glukoz, 8 g NH4CI, 5 g NaCl, 75 g 2 Na HPO 4 · çözülür 2H 2, O, 30 g KH 2 PO 4 ve 300 g disodyum süksinat heksahidrat (Na2 · süksinat · 6H &lt;sub&gt; 2 O; Bir rezervuar kavanoza 9.9 L DW bu deneyde kullanılan stres). </li><li> kelepçeler kullanılarak boru ile birlikte rezervuar kavanoz mühür. havalandırma deliğini mühür yok. </li><li> 15 dakika boyunca 121 ° C&#39;de bir otoklav içinde, rezervuar kavanoz sterilize edin. Sterilizasyon sonrasında, oda sıcaklığında kavanoz saklayın. </li><li> 2 g MgSO 4 · 7H 2, O, 1 g CaCl2, ve 100 ml DW (A çözeltisi) içinde 10 mg tiamin çözülür. </li><li> bir şırınga ve bir ön-sterilize edilmiş şırınga filtresinden (0.45 mikron gözenek filtresi) ile filtre solüsyonu için uygun değildir. </li><li> Bir rezervuar kavanoza süzüntüler solüsyonu ekleyin. </li><li> Aseptik rezervuar kavanoza sterilize silikon tüp bağlamak ve peristaltik pompalar takın. </li></ol></li><li> Yüksek stres Orta <ol><li> Bölüm 2.2 gibi orta hazırlayın, ama stresörün büyük bir konsantrasyon ile (yani, süksinat adaptasyon 3-5 g / L daha yüksek). Not: Bu protokol bir stres inci adaptasyon içinde orta yoluyla teslim edilebilir. sıcaklık, ajitasyon ya da aydınlatma gibi fiziksel stres durumunda, kültür buna göre tasarlanmış olmalıdır. </li></ol></li></ol> 3. İlk Yetiştirme <ol><li> Yabani tip E. tek bir koloni İnokülasyon Başlangıç ​​ortamı 4 ml içeren 15 ml&#39;lik deney tüpünde coli. </li><li> 37 ° C&#39;de 12 saat ve 220 rpm&#39;de sallanan bir kuluçka makinesinde test tüpünü inkübe edin. </li><li> Aseptik olarak transferi kemostat kavanoza ön kültür 1 ml. </li><li> 6 saat boyunca 37 ° C &#39;de, havalandırma (hava 50 ml / dakika) ve karıştırılarak (200 rpm) sağlayan, kemostat kavanoz inkübe edin. </li></ol> 4. Stres Adaptasyon <ol><li> Aseptik kemostat kavanoza pompalardan silikon hortumun ucunu. </li><li> çıkış pompası (10 ml / saat veya daha yüksek) başlatın ve kültür toplamak. Not: Kültür tipik olarak 4-8 ​​saat, ilk yetiştirme sonrasında, üslü fazda olması gerekir. </li><li> Chçıkış borusundan kültürün optik yoğunluğu (600 nm) eck. </li><li> Giriş pompası (0.1 saat -1 sulandırma bir orana karşı gelen 10 ml / sa,) başlatın. </li><li> her 24 saatte tüp çıkışından 600 nm&#39;de kültür optik yoğunluk kontrol edin. </li><li> 96 saat (9.6 kat ciro) ya da daha fazla kemostat çalıştırın. optik yoğunluk stabil ise, yüksek stres ortamı içeren rezervuar alışverişi. Optik yoğunluk 0.2 düşükse, 6 saat boyunca besleme giriş pompayı durdurun. giriş pompasını yeniden başlatın ve optik yoğunluk 0.2 üzerinde olup olmadığını kontrol edin. </li><li> Yavaş yavaş daha yüksek stres konsantrasyonunu ihtiva eden bir rezervuara değiştirerek stres konsantrasyonunu artırır. </li><li> O bir dönüm noktası ulaştığında adapte kültür örnekleri almak (örneğin, 100 g / L süksinat strese adapte suş) ileri genomik analiz için, ve mağaza. </li><li> Örnek depolama için, steril bir% 80 gliserol soluti kültür numunesi (0.5 mL) karışımıilgili (0.5 mi) ve -80 ° C&#39;de saklayın. Not: Mikroorganizma ALE sürecinde stres aşağılamak için bir yeteneği edinirse, fermantasyon kavanoz stres konsantrasyonu taze haznesinde aynı değildir. </li></ol> Stres adapte Uzama 5. Tek koloni izolasyonu <ol><li> Agar plaka orta (% 1.6 ağar) aynı stres içeren ve ortamın aynı konsantrasyonda hazırlayın. </li><li> kemostat gelen çıkış kültür (0.1 mi) plaka ve 16 saat 37 ° C&#39;de inkübe edin. </li><li> Steril kürdan ile plaka, tek koloniler aynı stres ihtiva eden 15 ml&#39;lik deney tüpleri ve kemostat aynı ortam konsantrasyonunda bunları inoküle ve 6 saat inkübe edilir. </li><li> Transfer ortamı 50 ml içeren 250 ml&#39;lik bir Erlenmeyer şişesi içinde bulundukları kültür çorbasından 1 mi. Hasat kültür sıvısının 0.5 ml her 1 saat ve 600 nm&#39;de OD&#39;yi ölçün. adapte strai büyüme hızını karşılaştırmakstres verilen yabani tip suşu edilene n. </li></ol>

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The authors have nothing to disclose.

Mikroorganizmalar nedeniyle hızlı büyüme oranı ve genetik çeşitliliğin hemen hemen tüm ortamlarda uyum yeteneğine sahiptirler. Adaptif laboratuvar evrim verilen koşullar altında yararlıdır spontan mutasyon barındıran bireysel organizmaların seçerek bir yol sağlar tasarlanmış koşullar altında gelişmeye mikroorganizmaları sağlar. kemostat tekniği aşağıdaki nedenlerle transfer teknikleri daha yapay tahrik evrimi elde etmek için daha sağlamdır, (a) sürekli bir o...

Mikroorganizmalar hayatta ve çeşitli ortamlara uyum sağlayabilir. Ağır stres altında, adaptasyon rastgele genomik mutasyonların ve sonraki pozitif seleksiyon 1-3 yararlı fenotip kazanması ile ortaya çıkabilir. Bu nedenle, mikrobiyal hücreler &quot;adaptif evrim&quot; olarak adlandırılır optimum büyüme için metabolik veya düzenleyici ağları değiştirerek uyum sağlayabilir. Bu tür süpermikroplar salgınları ve sağlam mikrobiyal suşların ortaya çıkması gibi yeni önemli mikrobiyal eğilimler, çok yakından stresli koşullar altında evrimi uyarlamalı ilişkilidir. tanımlanan laboratuvar koşullarında, moleküler evrim mekanizmaları incelemek ve hatta çeşitli uygulamalar için mikrobik evrimin yönünü kontrol edebiliyoruz. onlar büyük nüfusları korumak, hızlı bir şekilde yeniden ve oluşturmak ve Hom bakımı kolaydır: Çok hücreli organizmalardan farklı, tek hücreli canlılar aşağıdaki nedenlerden ötürü adaptif laboratuvar evrim (ALE) için uygundurogeneous ortamlar. DNA dizileme teknikleri ve yüksek verimli teknolojilerindeki son gelişmeler ile birlikte, ALE sistemik düzenleyici değişikliklere yol genomik değişikliklerin doğrudan gözlem sağlar. Mutasyon dinamikleri ve nüfus çeşitliliği de gözlemlenebilir. Genetik mühendisliği yöntemi ALE suşlarının 4,5 analizinden belirlenebilir. Kemostat kültür kararlı durum hücreleri elde etmek ve fermantasyon süreçleri 6 verimliliği artırmak için kullanılan bir yöntemdir. Taze ortam ilave edilir ve kültür sıvısı işlemi (ikinci orta ve biyokütle içerir) içinde toplanır. Uzun vadeli kemostat kültürü Bununla birlikte, kültürün kararlı durum verimliliği değiştirir ve kültür (Şekil 1a) sırasında spontan mutasyon ve seleksiyon birikimi getiriyor. Çeşitli seçim basınçlarında (stres) altında, mutasyonların birikimi artar. Uzun vadede stres kademeli bir artış<html> kemostat tekrarlanan sıvı bir ortamda bir katı ortam ve seri transferi (arasında, sıcaklık, pH, ozmotik basıncı, besin açlık, oksidasyon, toksik son ürün, vb Koloni transferi verilen stres karşı çalışma mutasyonlar, sürekli bir seçim sağlar küme kültür), araştırmacılara gelişti mikroorganizmaları (Şekil 1B ve 1C) elde edilmesine olanak sağlamaktadır. kemostat kültür karmaşık yöntemler gerektirmesine rağmen, çeşitlilik havuzu (tekrarlamalı ve nüfus büyüklüğü sayısı) koloni transfer ve seri transfer teknikleri ile elde edilenden daha yüksektir. tek tek hücrelerin kararlı stres maruziyeti ve kemostat kültürü (sabit durum) toplu kültür temelli tekniklerle karşılaştırıldığında ALE diğer faydaları şunlardır sırasında hücresel devlet varyasyon azalmıştır. Yüksek süksinat koşullara tabi Escherichia coli strese bağlı ALE Bu makalede tanıtıldı. iles / ftp_upload / 54446 / 54446fig1.jpg &quot;/&gt; Şekil 1: adaptif laboratuvar evrim Yöntemleri (A) Kemostat;. (B) Seri transferi; (C) koloni transferi. Üst rakamlar ALE yöntemleri kavramını göstermek ve alt rakamlar ALE sırasında büyüyen hücrelerin sayısını göstermektedir. <a href="https://www.jove.com/files/ftp_upload/54446/54446fig1large.jpg" target="_blank">Bu rakamın büyük halini görmek için lütfen buraya tıklayınız.</a>

<table border="0" cellpadding="0" cellspacing="0" width="573">
	<tbody>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Mini-chemostat fermentor</td>
			<td style="width:71px;">Biotron Inc.</td>
			<td style="width:119px;">-</td>
			<td style="width:167px;">manufactured by special order</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">silicon tubing</td>
			<td style="width:71px;">Cole-Parmer</td>
			<td style="width:119px;">Masterflex L/S 13</td>
			<td>tubing size can be varied depending on the dilution rate and the size of fermentor jar.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">reservoir jar</td>
			<td style="width:71px;">Bellco</td>
			<td style="width:119px;">Media storage bottle&#160;</td>
			<td>20 L</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">chemicals</td>
			<td style="width:71px;">Sigma-Aldrich</td>
			<td style="width:119px;">-</td>
			<td>reagent grade</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">glucose</td>
			<td style="width:71px;">Sigma-Aldrich</td>
			<td style="width:119px;">G5767</td>
			<td>ACS reagent</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">NH4Cl</td>
			<td style="width:71px;">Sigma-Aldrich</td>
			<td style="width:119px;">A9434</td>
			<td>for molecular biology, suitable for cell culture, &#8805;99.5%</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">NaCl</td>
			<td style="width:71px;">Sigma-Aldrich</td>
			<td align="right" style="width:119px;">746398</td>
			<td>ACS reagent, &#8805;99%</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Na2HPO4&#183;2H2O</td>
			<td style="width:71px;">Sigma-Aldrich</td>
			<td align="right" style="width:119px;">4272</td>
			<td>98.5-101%</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">KH2PO4&#160;</td>
			<td style="width:71px;">Sigma-Aldrich</td>
			<td align="right" style="width:119px;">795488</td>
			<td>ACS reagent, &#8805;99%</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">MgSO4&#183;7H2O</td>
			<td style="width:71px;">Sigma-Aldrich</td>
			<td align="right" style="width:119px;">230391</td>
			<td>ACS reagent, &#8805;98%</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">CaCl2</td>
			<td style="width:71px;">Sigma-Aldrich</td>
			<td align="right" style="width:119px;">793639</td>
			<td>ACS reagent, &#8805;96%</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">thiamine&#183;HCl&#160;</td>
			<td style="width:71px;">Sigma-Aldrich</td>
			<td style="width:119px;">T4625</td>
			<td>reagent grade, &#8805;99%</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Na2&#183;succinate&#183;6H2O</td>
			<td style="width:71px;">Sigma-Aldrich</td>
			<td style="width:119px;">S2378</td>
			<td>ReagentPlus, &#8805;99%</td>
		</tr>
	</tbody>
</table>

procedure for adaptive laboratory evolution of microorganisms using a chemostat

Natural evolution involves genetic diversity such as environmental change and a selection between small populations. Adaptive laboratory evolution (ALE) refers to the experimental situation in which evolution is observed using living organisms under controlled conditions and stressors; organisms are thereby artificially forced to make evolutionary changes. Microorganisms are subject to a variety of stressors in the environment and are capable of regulating certain stress-inducible proteins to increase their chances of survival. Naturally occurring spontaneous mutations bring about changes in a microorganism's genome that affect its chances of survival. Long-term exposure to chemostat culture provokes an accumulation of spontaneous mutations and renders the most adaptable strain dominant. Compared to the colony transfer and serial transfer methods, chemostat culture entails the highest number of cell divisions and, therefore, the highest number of diverse populations. Although chemostat culture for ALE requires more complicated culture devices, it is less labor intensive once the operation begins. Comparative genomic and transcriptome analyses of the adapted strain provide evolutionary clues as to how the stressors contribute to mutations that overcome the stress. The goal of the current paper is to bring about accelerated evolution of microorganisms under controlled laboratory conditions.

Yüksek süksinat stres adaptasyonu için, vahşi tip E. coli W3110 suşu D bir kemostat kültürlenmiştir = 0.1 saat -1 270 gün (Şekil 2). <img alt="şekil 2" src="/files/ftp_upload/54446/54446fig2.jpg" /> Şekil 2: E. Yüksek süksinat stres adaptasyonu E. coli kemostat kültür kullanarak W3110. İnce oklar stresörün konsantrasyonu artmış edildiği kez gösterir ve kalın o...

Watch this Scientific Journal Video about Procedure for Adaptive Laboratory Evolution of Microorganisms Using a Chemostat at JoVE.com

Kemostat Kullanarak Mikroorganizmaların Uyarlanabilir Laboratuvar Evrimi Prosedürü | Genetik | Video

Procedure for Adaptive Laboratory Evolution of Microorganisms Using a Chemostat

Burada, biz kemostat kültür kullanarak koşullar altında mikroorganizmaların adaptif laboratuvar evrimini elde etmek için bir protokol mevcut. Ayrıca, gelişmiş soyunun genomik analiz tartışılmıştır.

Bir Kemostat kullanarak Mikroorganizmaların Adaptif Laboratuvarı Evolution Prosedürü

Natural evolution involves genetic diversity such as environmental change and a selection between small populations. Adaptive laboratory evolution (ALE) ...

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14.1K Görüntüleme.  Korea Research Institute of Bioscience and Biotechnology (KRIBB).  Burada, biz kemostat kültür kullanarak koşullar altında mikroorganizmaların adaptif laboratuvar evrimini elde etmek için bir protokol mevcut. Ayrıca, gelişmiş soyunun genomik analiz tartışılmıştır. 

Video: Procedure for Adaptive Laboratory Evolution of Microorganisms Using a Chemostat

Design and Use of a Low Cost, Automated Morbidostat for Adaptive Evolution of Bacteria Under Antibiotic Drug Selection

We describe a low cost, configurable morbidostat for characterizing the evolutionary pathway of antibiotic resistance. The morbidostat is a bacterial culture device that continuously monitors bacterial growth and dynamically adjusts the drug concentration to constantly challenge the bacteria as they evolve to acquire drug resistance. The device features a working volume of ~10 ml and is fully automated and equipped with optical density measurement and micro-pumps for medium and drug delivery. To validate the platform, we measured the stepwise acquisition of trimethoprim resistance in Escherichia coli MG 1655, and integrated the device with a multiplexed microfluidic platform to investigate cell morphology and antibiotic susceptibility. The approach can be up-scaled to laboratory studies of antibiotic drug resistance, and is extendible to adaptive evolution for strain improvements in metabolic engineering and other bacterial culture experiments.

We describe a low cost, configurable morbidostat that enables the characterization of antibiotic drug resistance by dynamically adjusting the drug concentration. The device can be integrated with a multiplexed microfluidic platform. The approach can be scaled up for laboratory antibiotic drug resistance studies.

Tasarım ve Düşük Maliyetli kullanımı, Otomatik Morbidostat Bakterilerin Adaptif Evolution için antibiyotik ilaç Seçimi Altında

We describe a low cost, configurable morbidostat for characterizing the evolutionary pathway of antibiotic resistance. The morbidostat is a bacterial ...

Genetik

CRISPR/Cas9-mediated Targeted Integration In Vivo Using a Homology-mediated End Joining-based Strategy

As a promising genome editing platform, the CRISPR/Cas9 system has great potential for efficient genetic manipulation, especially for targeted integration of transgenes. However, due to the low efficiency of homologous recombination (HR) and various indel mutations of non-homologous end joining (NHEJ)-based strategies in non-dividing cells, in vivo genome editing remains a great challenge. Here, we describe a homology-mediated end joining (HMEJ)-based CRISPR/Cas9 system for efficient in vivo precise targeted integration. In this system, the targeted genome and the donor vector containing homology arms (~800 bp) flanked by single guide RNA (sgRNA) target sequences are cleaved by CRISPR/Cas9. This HMEJ-based strategy achieves efficient transgene integration in mouse zygotes, as well as in hepatocytes in vivo. Moreover, a HMEJ-based strategy offers an efficient approach for correction of fumarylacetoacetate hydrolase (Fah) mutation in the hepatocytes and rescues Fah-deficiency induced liver failure mice. Taken together, focusing on targeted integration, this HMEJ-based strategy provides a promising tool for a variety of applications, including generation of genetically modified animal models and targeted gene therapies.

CRISPR/Cas9-mediated Targeted Integration In Vivo Using a Homology-mediated End Joining-based Strategy

The clustered regularly interspaced short palindromic repeats/CRISPR associated protein 9 (CRISPR/Cas9) system provides a promising tool for genetic engineering, and opens up the possibility of targeted integration of transgenes. We describe a homology-mediated end joining (HMEJ)-based strategy for efficient DNA targeted integration in vivo and targeted gene therapies using CRISPR/Cas9.

Bir bitiş homoloji-aracılı katılmadan tabanlı strateji kullanarak hedeflenen Integration CRISPR/Cas9-aracılı Vivo içinde

As a promising genome editing platform, the CRISPR/Cas9 system has great potential for efficient genetic manipulation, especially for targeted integration ...

Testing the Role of Multicopy Plasmids in the Evolution of Antibiotic Resistance

Multicopy plasmids are extremely abundant in prokaryotes but their role in bacterial evolution remains poorly understood. We recently showed that the increase in gene copy number per cell provided by multicopy plasmids could accelerate the evolution of plasmid-encoded genes. In this work, we present an experimental system to test the ability of multicopy plasmids to promote gene evolution. Using simple molecular biology methods, we constructed a model system where an antibiotic resistance gene can be inserted into Escherichia coli MG1655, either in the chromosome or on a multicopy plasmid. We use an experimental evolution approach to propagate the different strains under increasing concentrations of antibiotics and we measure survival of bacterial populations over time. The choice of the antibiotic molecule and the resistance gene is so that the gene can only confer resistance through the acquisition of mutations. This &#34;evolutionary rescue&#34; approach provides a simple method to test the potential of multicopy plasmids to promote the acquisition of antibiotic resistance. In the next step of the experimental system, the molecular bases of antibiotic resistance are characterized. To identify mutations responsible for the acquisition of antibiotic resistance we use deep DNA sequencing of samples obtained from whole populations and clones. Finally, to confirm the role of the mutations in the gene under study, we reconstruct them in the parental background and test the resistance phenotype of the resulting strains.

Here we present an experimental method to test the role of multicopy plasmids in the evolution of antibiotic resistance.

Multicopy plazmid rolü antibiyotik direnci gelişimi test

Multicopy plasmids are extremely abundant in prokaryotes but their role in bacterial evolution remains poorly understood. We recently showed that the ...

Genome-wide Surveillance of Transcription Errors in Eukaryotic Organisms

Accurate transcription is required for the faithful expression of genetic information. Surprisingly though, little is known about the mechanisms that control the fidelity of transcription. To fill this gap in scientific knowledge, we recently optimized the circle-sequencing assay to detect transcription errors throughout the transcriptome of Saccharomyces cerevisiae, Drosophila melanogaster, and Caenorhabditis elegans. This protocol will provide researchers with a powerful new tool to map the landscape of transcription errors in eukaryotic cells so that the mechanisms that control the fidelity of transcription can be elucidated in unprecedented detail.

This protocol provides researchers with a new tool to monitor the fidelity of transcription in multiple model organisms.

Ökaryotlarda transkripsiyon hataları genom çapında gözetim

Accurate transcription is required for the faithful expression of genetic information. Surprisingly though, little is known about the mechanisms that ...

High-Resolution Comparison of Bacterial Conjugation Frequencies

Bacterial conjugation is an important step in the horizontal transfer of antibiotic resistance genes via a conjugative DNA element. In-depth comparisons of conjugation frequency under different conditions are required to understand how the conjugative element spreads in nature. However, conventional methods for comparing conjugation frequency are not appropriate for in-depth comparisons because of the high background caused by the occurrence of additional conjugation events on the selective plate. We successfully reduced the background by introducing a most probable number (MPN) method and a higher concentration of antibiotics to prevent further conjugation in selective liquid medium. In addition, we developed a protocol for estimating the probability of how often donor cells initiate conjugation by sorting single donor cells into recipient pools by fluorescence-activated cell sorting (FACS). Using two plasmids, pBP136 and pCAR1, the differences in conjugation frequency in Pseudomonas putida cells could be detected in liquid medium at different stirring rates. The frequencies of conjugation initiation were higher for pBP136 than for pCAR1. Using these results, we can better understand the conjugation features in these two plasmids.

With an aim to understand the behaviors of various bacterial conjugative DNA elements under different conditions, we describe a protocol for detecting differences in conjugation frequency, with high resolution, to estimate how efficiently the donor bacterium initiates conjugation.

Bakteriyel konjugasyon frekans yüksek çözünürlüklü karşılaştırma

Bacterial conjugation is an important step in the horizontal transfer of antibiotic resistance genes via a conjugative DNA element. In-depth comparisons ...

Producing Gene Deletions in Escherichia coli by P1 Transduction with Excisable Antibiotic Resistance Cassettes

A first approach to study the function of an unknown gene in bacteria is to create a knock-out of this gene. Here, we describe a robust and fast protocol for transferring gene deletion mutations from one Escherichia coli strain to another by using generalized transduction with the bacteriophage P1. This method requires that the mutation be selectable (e.g., based on gene disruptions using antibiotic cassette insertions). Such antibiotic cassettes can be mobilized from a donor strain and introduced into a recipient strain of interest to quickly and easily generate a gene deletion mutant. The antibiotic cassette can be designed to include flippase recognition sites that allow the excision of the cassette by a site-specific recombinase to produce a clean knock-out with only a ~100-base-pair-long scar sequence in the genome. We demonstrate the protocol by knocking out the tamA gene encoding an assembly factor involved in autotransporter biogenesis and test the effect of this knock-out on the biogenesis and function of two trimeric autotransporter adhesins. Though gene deletion by P1 transduction has its limitations, the ease and speed of its implementation make it an attractive alternative to other methods of gene deletion.

Producing Gene Deletions in Escherichia coli by P1 Transduction with Excisable Antibiotic Resistance Cassettes

Here we present a protocol for the use of pre-existing antibiotic resistance-cassette deletion constructs as a basis for making deletion mutants in other E. coli strains. Such deletion mutations can be mobilized and inserted into the corresponding locus of a recipient strain using P1 bacteriophage transduction.

Escherichia coli Excisable antibiyotik direnci kasetleri ile P1 iletim tarafından üreten gen silme

A first approach to study the function of an unknown gene in bacteria is to create a knock-out of this gene. Here, we describe a robust and fast protocol ...

qKAT: Quantitative Semi-automated Typing of Killer-cell Immunoglobulin-like Receptor Genes

Killer cell immunoglobulin-like receptors (KIRs) are a set of inhibitory and activating immune receptors, on natural killer (NK) and T cells, encoded by a polymorphic cluster of genes on chromosome 19. Their best-characterized ligands are the human leukocyte antigen (HLA) molecules that are encoded within the major histocompatibility complex (MHC) locus on chromosome 6. There is substantial evidence that they play a significant role in immunity, reproduction, and transplantation, making it crucial to have techniques that can accurately genotype them. However, high-sequence homology, as well as allelic and copy number variation, make it difficult to design methods that can accurately and efficiently genotype all KIR genes. Traditional methods are usually limited in the resolution of data obtained, throughput, cost-effectiveness, and the time taken for setting up and running the experiments. We describe a method called quantitative KIR semi-automated typing (qKAT), which is a high-throughput multiplex real-time polymerase chain reaction method that can determine the gene copy numbers for all genes in the KIR locus. qKAT is a simple high-throughput method that can provide high-resolution KIR copy number data, which can be further used to infer the variations in the structurally polymorphic haplotypes that encompass them. This copy number and haplotype data can be beneficial for studies on large-scale disease associations, population genetics, as well as investigations on expression and functional interactions between KIR and HLA.

Quantitative killer cell immunoglobulin-like receptor (KIR) semi-automated typing (qKAT) is a simple, high-throughput, and cost-effective method to copy number type KIR genes for their application in population and disease association studies.

qKAT: nicel Semi-automated yazmaktan katil hücreli immünglobulin benzeri reseptör gen

Killer cell immunoglobulin-like receptors (KIRs) are a set of inhibitory and activating immune receptors, on natural killer (NK) and T cells, encoded by a ...

Using Sniper-Cas9 to Minimize Off-target Effects of CRISPR-Cas9 Without the Loss of On-target Activity Via Directed Evolution

The development of clustered regularly interspaced short palindromic repeats (CRISPR)-associated protein 9 (Cas9) into therapeutic modalities requires the avoidance of its potentially deleterious off-target effects. Several methods have been devised to reduce such effects. Here, we present an Escherichia coli-based directed evolution method called Sniper-screen to obtain a Cas9 variant with optimized specificity and retained on-target activity, called Sniper-Cas9. Using Sniper-screen, positive and negative selection can be performed simultaneously. The screen can also be repeated with other single-guide RNA (sgRNA) sequences to enrich for the true positive hits. By using the CMV-PltetO1 dual promoter to express Cas9 variants, the performance of the pooled library can be quickly checked in mammalian cells. Methods to increase the specificity of Sniper-Cas9 are also described. First, the use of truncated sgRNAs has previously been shown to increase Cas9 specificity. Unlike other engineered Cas9s, Sniper-Cas9 retains a wild-type (WT) level of on-target activity when combined with truncated sgRNAs. Second, the delivery of Sniper-Cas9 in a ribonucleoprotein (RNP) format instead of a plasmid format is possible without affecting its on-target activity.

Here, we present a protocol to optimize CRISPR-Cas9 to achieve a higher specificity without the loss of on-target activity. We use a directed evolution approach called Sniper-screen to find a mutant Cas9 with the desired characteristics. Sniper-Cas9 is compatible with truncated single-guide RNAs and delivery in a ribonucleoprotein format, well-known strategies for achieving higher specificities.

Keskin nişancı-Cas9 CRISPR-Cas9 hedef olarak faaliyet yönlendirilmiş evrim yoluyla kaybı olmadan hedef kapalı etkilerini en aza indirmek için kullanma

The development of clustered regularly interspaced short palindromic repeats (CRISPR)-associated protein 9 (Cas9) into therapeutic modalities requires the ...

A FACS-based Protocol to Isolate RNA from the Secondary Cells of Drosophila Male Accessory Glands

To understand the function of an organ, it is often useful to understand the role of its constituent cell populations. Unfortunately, the rarity of individual cell populations often makes it difficult to obtain enough material for molecular studies. For example, the accessory gland of the Drosophila male reproductive system contains two distinct secretory cell types. The main cells make up 96% of the secretory cells of the gland, while the secondary cells (SC) make up the remaining 4% of cells (about 80 cells per male). Although both cell types produce important components of the seminal fluid, only a few genes are known to be specific to the SCs. The rarity of SCs has, thus far, hindered transcriptomic analysis study of this important cell type. Here, a method is presented that allows for the purification of SCs for RNA extraction and sequencing. The protocol consists in first dissecting glands from flies expressing a SC-specific GFP reporter and then subjecting these glands to protease digestion and mechanical dissociation to obtain individual cells. Following these steps, individual, living, GFP-marked cells are sorted using a fluorescent activated cell sorter (FACS) for RNA purification. This procedure yields SC-specific RNAs from ~40 males per condition for downstream RT-qPCR and/or RNA sequencing in the course of one day. The rapidity and simplicity of the procedure allows for the transcriptomes of many different flies, from different genotypes or environmental conditions, to be determined in a short period of time.

A FACS-based Protocol to Isolate RNA from the Secondary Cells of Drosophila Male Accessory Glands

Here, we present a protocol to dissociate and sort a specific cell population from the Drosophila male accessory glands (secondary cells) for RNA sequencing and RT-qPCR. Cell isolation is accomplished through FACS purification of GFP-expressing secondary cells after a multistep-dissociation process requiring dissection, proteases digestion and mechanical dispersion.

Drosophila Erkek Aksesuar Bezlerinin Sekonder Hücrelerinden RNA'yı Izole etmek için FACS tabanlı Protokol

To understand the function of an organ, it is often useful to understand the role of its constituent cell populations. Unfortunately, the rarity of ...

A New Toolkit for Evaluating Gene Functions using Conditional Cas9 Stabilization

The clustered regularly interspaced short palindromic repeat- (CRISPR-) associated protein 9 (CRISPR/Cas9) technology has become a prevalent laboratory tool to introduce accurate and targeted modifications in the genome. Its enormous popularity and rapid spread are attributed to its easy use and accuracy compared to its predecessors. Yet, the constitutive activation of the system has limited applications. In this paper, we describe a new method that allows temporal control of CRISPR/Cas9 activity based on conditional stabilization of the Cas9 protein. Fusing an engineered mutant of the rapamycin-binding protein FKBP12 to Cas9 (DD-Cas9) enables the rapid degradation of Cas9 that in turn can be stabilized by the presence of an FKBP12 synthetic ligand (Shield-1). Unlike other inducible methods, this system can be adapted easily to generate bi-cistronic systems to co-express DD-Cas9 with another gene of interest, without conditional regulation of the second gene. This method enables the generation of traceable systems as well as the parallel, independent manipulation of alleles targeted by Cas9 nuclease. The platform of this method can be used for the systematic identification and characterization of essential genes and the interrogation of the functional interactions of genes in in vitro and in vivo settings.

Here, we describe a genome-editing tool based on the temporal and conditional stabilization of clustered regularly interspaced short palindromic repeat- (CRISPR-) associated protein 9 (Cas9) under the small molecule, Shield-1. The method can be used for cultured cells and animal models.

Koşullu Cas9 Stabilizasyonunu Kullanarak Gen fonksiyonlarını değerlendirmek için Yeni Bir Araç Seti

The clustered regularly interspaced short palindromic repeat- (CRISPR-) associated protein 9 (CRISPR/Cas9) technology has become a prevalent laboratory ...