Este trabajo fue financiado por beca NIH GM117446 a A.B.

1. preparación de células de flujo Cytometry clasificación
<ol><li>Inocular tubos de ensayo de 15 mL que contiene 8 mL de caldo YEPD tal que los cultivos alcanzan una densidad de 5 x 106 a 1.5 x 107 células por mL después de crecimiento durante la noche (véase la discusión Nota 1).</li>
	<li>Desactivación de las células de levadura (1.400 x g, a temperatura ambiente o 4 ° C) en un tubo de centrífuga de 15 mL tapón durante 5 min, resuspender las células en etanol al de 70% 1.5 mL y transfiéralo a un tubo de microcentrífuga 1.6 mL, dejando este sit 1 h a temperatura ambiente o por lo menos 3 h de hielo ( se puede almacenar indefinidamente a 4 ° C) (véase punto de discusión (2)).</li>
	<li>Desactivación de las células de levadura en la microcentrífuga (14.000 x g, 4 ° C) durante 1 minuto, resuspender en 1 mL citrato de sodio 50 mM, pH 7.2, giro (14.000 x g, 4 ° C) durante 1 minuto, aspirar el sobrenadante, resuspender en 1 mL citrato de sodio 50 mM, pH 7.2 , que contiene 0.25 mg/mL solución de Rnasa por 1 h a 50 ° C o durante la noche a 37 ° C en baño de agua o bloque de calor.</li>
	<li>Añadir 50 μl proteinasa K solución (20 mg/mL resuspendió en 10 mM Tris, pH 7,5, 2 mM CaCl2, peso de 50% de glicerol de volumen) e incubar 1 h a 50 ° C.</li>
	<li>Desactivación de las células (14.000 x g, 4 º C), resuspender las células en 1 mL citrato de sodio 50 mM, pH 7.2, desactivación (14.000 x g, 4 º C), aspirar el sobrenadante con vacío, resuspender en 1 mL 1 μm ácido nucleico verde tensión resuspendió en citrato de sodio 50 mM , pH 7.2 e incubar en la oscuridad durante 1 h a temperatura ambiente, someter a ultrasonidos 2 x 2 s cada (2 vatios de potencia de salida).</li>
</ol>2. celda de clasificación
<ol><li>Utilizando un clasificador de celda, ordenar las células según el contenido de ADN en las fases G1, S, "primera G2" y "G2 tardía", que recoge al menos 1,6 millones células haploides de cada fase del ciclo celular como en la figura 1 (véase punto de discusión (3)).</li>
	<li>Células de transferencia a tubos de microcentrífuga y desactivación de las células durante 20 min a 14.000 xg a 4 ° C en la microcentrífuga y aspirar sobrenadante con vacío (la pelotilla puede guardarse congelada a-20 ° C por tiempo indefinido; véase el punto (4)).</li>
</ol>3. DNA extracción y la preparación de la secuenciación de las bibliotecas
Nota: Los pasos siguientes se basan en "Protocolo" en la extracción de ADN genómico de levadura Kit (véase Tabla de materiales).
<ol><li>Añadir 120 μl de "Tampón de digestión", un tampón patentado que permite enzimas líticas levadura y digerir la pared celular y 5 μl de enzima lítica de la levadura, agite con un vórtex, incubar a 37 ° C durante 40-60 min.</li>
	<li>Añadir 120 μl de tampón de lisis del"," un propiedad tampón que contiene detergente y vórtice dura de 10-20 s.</li>
	<li>Añadir cloroformo μl 250 - mezclar bien durante 1 minuto.</li>
	<li>Girar a la velocidad máxima en una microcentrífuga durante 2 minutos.</li>
	<li>Cargar el sobrenadante a la columna de unión de ADN y centrifugar a máxima velocidad en una microcentrífuga durante 1 minuto.</li>
	<li>Añadir 300 μL de "ADN lavado Tampón", un tampón patentado que contiene etanol y centrifugue durante 1 min a velocidad máxima en una microcentrífuga. Deseche el flujo a través, añadir 300 μL de tampón de lavado de ADN y repita el proceso de lavado.</li>
	<li>Transferir la columna spin a un tubo de microcentrífuga fresco, añadir 60 μL de agua (no TE) - esperar 1-3 minutos y luego centrifugar durante 10 s a fin de eluir el ADN.</li>
	<li>Medir la concentración al añadir 5 μl de ADN a 195 μl del reactivo de alta sensibilidad de dsDNA que ha sido diluido 1: 200 en buffer de alta sensibilidad de dsDNA y luego medir la fluorescencia en un fluorómetro, con 10 μl de estándares suministrados para la calibración; esperar entre 10 y 50 ng de rendimiento total de ADN.</li>
	<li>Someter a ultrasonidos (pico incidente energía 450, Factor de servicio 30%, ciclos por estallar 200, tratamiento tiempo 60 s, 6 de nivel de agua) para romper el ADN en fragmentos de 250-350 bp.</li>
	<li>Preparar una biblioteca utilizando el kit de preparación de muestras de ADN y secuenciarlo (lecturas del solo-fin de bp 50 por lo menos 10 millones) en el instrumento de la secuencia de DNA en modo rápido (ver nota de discusión (5)).</li>
</ol>4. Análisis de la secuencia de datos y generación de replicación de perfiles
<ol><li>Alinear secuencias de genoma de sacCer3 de Saccharomyces cerevisiae con Gsnap12 (ver nota de discusión (6)).</li>
	<li>Determinar por la base par Lee profundidades utilizando "genomeCoverageBed" software13 de Bedtools.</li>
	<li>Quitar puntas artefactuales en profundidades de lectura, si está presente (ver nota de discusión (7)).</li>
	<li>Lisa Lee profundidades por cromosoma usando medias en una kb 20 corredera ventana mediante la función "runMean" en R paquete "caTools" (ver nota de discusión (8)).</li>
	<li>Parcela Lee profundidades en fase S, G2 temprana y tardío G2 como un porcentaje de profundidad leer completamente replicado (ver nota de discusión (9)).</li>
</ol>

<ol>
	<li>Fragkos, M., Ganier, O., Coulombe, P., Mechali, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=DNA+replication+origin+activation+in+space+and+time.">DNA replication origin activation in space and time.</a> Nat Rev Mol Cell Biol. 16, 360-374 (2015).</li><li>Santocanale, C., Diffley, J. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Mec1-+and+Rad53-dependent+checkpoint+controls+late-firing+origins+of+DNA+replication.">A Mec1- and Rad53-dependent checkpoint controls late-firing origins of DNA replication.</a> Nature. 395, 615-618 (1998).</li><li>Brewer, B. J., Fangman, W. 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+replication+fork+barrier+at+the+3'+end+of+yeast+ribosomal+RNA+genes.">A replication fork barrier at the 3' end of yeast ribosomal RNA genes.</a> Cell. 55, 637-643 (1988).</li><li>Raghuraman, M. 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=Replication+dynamics+of+the+yeast+genome.">Replication dynamics of the yeast genome.</a> Science. 294, 115-121 (2001).</li><li>Muller, C. A., Nieduszynski, C. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Conservation+of+replication+timing+reveals+global+and+local+regulation+of+replication+origin+activity.">Conservation of replication timing reveals global and local regulation of replication origin activity.</a> Genome Res. 22, 1953-1962 (2012).</li><li>Koren, A., Soifer, I., Barkai, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=MRC1-dependent+scaling+of+the+budding+yeast+DNA+replication+timing+program.">MRC1-dependent scaling of the budding yeast DNA replication timing program.</a> Genome Res. 20, 781-790 (2010).</li><li>Lang, G. I., Murray, A. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mutation+rates+across+budding+yeast+chromosome+VI+are+correlated+with+replication+timing.">Mutation rates across budding yeast chromosome VI are correlated with replication timing.</a> Genome Biol Evol. 3, 799-811 (2011).</li><li>Durkin, S. G., Glover, T. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chromosome+fragile+sites.">Chromosome fragile sites.</a> Annu Rev Genet. 41, 169-192 (2007).</li><li>Dillon, L. W., Burrow, A. A., Wang, Y. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=DNA+instability+at+chromosomal+fragile+sites+in+cancer.">DNA instability at chromosomal fragile sites in cancer.</a> Curr Genomics. 11, 326-337 (2010).</li><li>Widrow, R. J., Hansen, R. S., Kawame, H., Gartler, S. M., Laird, C. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Very+late+DNA+replication+in+the+human+cell+cycle.">Very late DNA replication in the human cell cycle.</a> Proc Natl Acad Sci U S A. 95, 11246-11250 (1998).</li><li>Foss, E. J., 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=SIR2+suppresses+replication+gaps+and+genome+instability+by+balancing+replication+between+repetitive+and+unique+sequences.">SIR2 suppresses replication gaps and genome instability by balancing replication between repetitive and unique sequences.</a> Proc Natl Acad Sci U S A. 114, 552-557 (2017).</li><li>Wu, T. D., Reeder, J., Lawrence, M., Becker, G., Brauer, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=GMAP+and+GSNAP+for+Genomic+Sequence+Alignment:+Enhancements+to+Speed,+Accuracy,+and+Functionality.">GMAP and GSNAP for Genomic Sequence Alignment: Enhancements to Speed, Accuracy, and Functionality.</a> Methods Mol Biol. 1418, 283-334 (2016).</li><li>Quinlan, A. R., Hall, I. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=BEDTools:+a+flexible+suite+of+utilities+for+comparing+genomic+features.">BEDTools: a flexible suite of utilities for comparing genomic features.</a> Bioinformatics. 26, 841-842 (2010).</li><li>Langmead, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Aligning+short+sequencing+reads+with+Bowtie.">Aligning short sequencing reads with Bowtie.</a> Curr Protoc Bioinformatics. , 17 (2010).</li><li>Li, H., Durbin, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fast+and+accurate+short+read+alignment+with+Burrows-Wheeler+transform.">Fast and accurate short read alignment with Burrows-Wheeler transform.</a> Bioinformatics. 25, 1754-1760 (2009).</li><li>Kellis, M., Birren, B. W., Lander, E. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Proof+and+evolutionary+analysis+of+ancient+genome+duplication+in+the+yeast+Saccharomyces+cerevisiae.">Proof and evolutionary analysis of ancient genome duplication in the yeast Saccharomyces cerevisiae.</a> Nature. 428, 617-624 (2004).</li><li>Goodwin, S., McPherson, J. D., McCombie, W. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Coming+of+age:+ten+years+of+next-generation+sequencing+technologies.">Coming of age: ten years of next-generation sequencing technologies.</a> Nat Rev Genet. 17, 333-351 (2016).</li></ol>

Los autores no tienen nada que revelar.

Mientras que esta técnica es robusta y relativamente directo, una atención especial debería destinarse a los siguientes:
(1) recomendamos que las culturas crecen durante al menos 12 h antes de llegar a la fase de registro, ya que las diferencias se manifiestan en ciclo celular distribuciones si las culturas son cosechadas después de haber alcanzado la densidad deseada a 4 h después de la inoculación. Nuestra hipótesis es que una distribución de ciclo celular que ha alcanzado un equilib...

Replicación del genoma eucariota se inicia en múltiples sitios discretos, llamados origen de replicación, de que la replicación horquillas proceden en ambas direcciones (revisados en Fragkos et al., 20151). Orígenes varían en su tiempo y eficiencia de la cocción, y se han desarrollado varias técnicas para supervisar la actividad de origen de replicación y aclarar las causas de esta variación. De niveles de single-stranded DNA2, que se forma alrededor de origen activo, puede inferirse la actividad de orígenes individuales o mediante el uso de electroforesis en 2D para supervisar la replicación específica intermedios3, que pueden ser detectadas con sondas radiactivas. Ambas de estas técnicas se aplican más fácilmente en S. cerevisiae que en células de mamífero, porque orígenes se limitan a secuencias específicas conocidas en la antigua. Con el advenimiento de los microarrays, llegó a ser posible evaluar origen disparando a nivel mundial. Esto fue hecho primero por etiquetado ADN con isótopos pesados, liberación de las células de un bloque de G1 en medio que contiene isótopos ligeros y monitoreo luego de la formación de pesados ligeros híbridos ADN en el genoma4. La introducción de secuenciación de alto rendimiento permitido genoma similares monitoreo de la actividad de origen sin el requisito de etiquetado isotópico caro. Las células fueron clasificadas en un citómetro de flujo según el contenido de ADN y su ADN sometido a secuenciación profunda. Porque la cobertura de secuencia procede de 1 x a 2 x en el transcurso de la fase S, sincronización de replicación relativa puede evaluarse comparando profundidades lecturas de células en fase S que en G1 o G25,6. Estas técnicas, aplicadas particularmente a levadura, condujeron a una comprensión más profunda de cómo proteínas de replicación de ADN, secuencia de la DNA y estructura de la cromatina regulan eficiencia y tiempo de origen.
La transmisión fiel de la información genética durante la proliferación celular requiere no sólo exitosa iniciación de la replicación del ADN, que ocurre en el origen, pero también superación de replicación, que ocurre el encuentro de las horquillas de replicación. Como iniciación de la replicación, el momento de la terminación de la replicación varía a lo largo del genoma con ciertas regiones restantes sin replicar hasta tarde en el ciclo celular. Tales regiones pueden ser particularmente distantes de orígenes de replicación activa o pueden contener secuencias o estructuras de cromatina que impiden polimerasas de la DNA. Tarde replicar las regiones puede manifestarse como sitios frágiles, que se asocian a fractura cromosómica y mayores tasas de mutación y se han implicado en cáncer y envejecimiento7,8,9. Sin embargo, a pesar de la importancia de la correcta terminación de la replicación del ADN en el mantenimiento de la estabilidad del genoma, nuestra comprensión de dónde y cómo esto ocurre ha retrasado lejos detrás de la iniciación de la replicación. Y mientras que los genes individuales cuya replicación tardía se ha asociado con la enfermedad han sido estudiados con, por ejemplo, qPCR10, globales estudios dirigidos a dilucidar las localizaciones y causas de la última replicación han faltado subyacentes. Aquí describimos una técnica que nos referimos a como "G2 seq" en el que combinamos la citometría de flujo con secuenciación de alto rendimiento para arrojar luz sobre la terminación de la replicación del genoma de la levadura11. Con pequeñas modificaciones, este protocolo puede ser adaptado a cualquier célula que puede ser flujo y ordenada según el contenido de ADN.

<table width="722">
	<tbody>
		<tr height="21">
			<td height="21" style="width:301px;height:21px;">YeaStar Genomic DNA kit</td>
			<td style="width:135px;">Genesee Scientific</td>
			<td style="width:119px;">11-323</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="width:301px;height:21px;">1 &#181;M SYTOX Green</td>
			<td style="width:135px;">ThermoFisher</td>
			<td style="width:119px;">57020</td>
			<td>resuspend in 50 mM sodium citrate, pH 7.2</td>
		</tr>
		<tr height="21">
			<td height="21" style="width:301px;height:21px;">50 mM sodium citrate, pH 7.2</td>
			<td style="width:135px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="147">
			<td height="147" style="width:301px;height:147px;">RNase solution (0.25 mg / mL)</td>
			<td style="width:135px;">Sigma</td>
			<td style="width:119px;">R6513</td>
			<td style="width:167px;">0.25 mg / mL RNaseA resuspended in 50 mM sodium citrate, pH 7.2, boil RNase solution for 10 minutes before the first use only, and from then on store at -20&#176;</td>
		</tr>
		<tr height="42">
			<td height="42" style="width:301px;height:42px;">proteinase K solution (20 mg / mL)</td>
			<td style="width:135px;">ThermoFisher / Invitrogen</td>
			<td style="width:119px;">25530-015</td>
			<td>resuspend in 10 mM Tris, pH 7.5, 2 mM CaCl2, 50% glycerol, store at -20&#176;C</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Model 50 Sonic Dismembrator</td>
			<td style="width:135px;">Fisher Scientific</td>
			<td>FB50A220</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="width:301px;height:21px;">BD Biosciences FACSAria II</td>
			<td style="width:135px;">BD Biosciences</td>
			<td>644832</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="width:301px;height:21px;">Zymo-spin III columns</td>
			<td style="width:135px;">Zymo Research</td>
			<td style="width:119px;">C1005</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="width:301px;height:21px;">Qubit dsDNA HS Assay Kit</td>
			<td style="width:135px;">ThermoFisher</td>
			<td style="width:119px;">Q32851</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="width:301px;height:21px;">Qubit 3.0 Fluorometer</td>
			<td style="width:135px;">ThermoFisher</td>
			<td style="width:119px;">Q33216</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Covaris Model LE220 Focused-Ultrasonicator</td>
			<td style="width:135px;">Covaris</td>
			<td style="width:119px;">500219</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="width:301px;height:21px;">Illumina TruSeq DNA LT Sample Prep Kit</td>
			<td style="width:135px;">Illumina</td>
			<td>15026486</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="width:301px;height:21px;">Illumina HiSeq 2500 instrument</td>
			<td style="width:135px;">Illumina</td>
			<td>SY&#8211;401&#8211;2501&#160;</td>
			<td></td>
		</tr>
		<tr height="63">
			<td height="63" style="width:301px;height:63px;">gsnap alignment software</td>
			<td style="width:135px;">open source software / Genentech</td>
			<td style="width:119px;"></td>
			<td style="width:167px;">http://research-pub.gene.com/gmap</td>
		</tr>
	</tbody>
</table>

g2-seq: a high throughput sequencing-based technique for identifying late replicating regions of the genome

Numerosas técnicas se han desarrollado para seguir el progreso de la replicación del ADN a través de la fase S del ciclo celular. La mayoría de estas técnicas se han dirigido hacia la aclaración de la ubicación y el momento de inicio de la duplicación del genoma en lugar de su realización. Sin embargo, es fundamental que entendemos regiones del genoma que son última completar la replicación, porque estas regiones sufren niveles elevados de rotura cromosómica y mutación, y han sido asociados con la enfermedad y el envejecimiento. Aquí describimos cómo hemos ampliado una técnica que se ha utilizado para vigilar la iniciación de la replicación en cambio identificar las regiones del genoma última replicación completa. Este enfoque se basa en una combinación de citometría de flujo y la secuenciación de alto rendimiento. Aunque este informe se centra en la aplicación de esta técnica a la levadura, el enfoque puede utilizarse con cualquier célula que se puede ordenar en un citómetro de flujo según el contenido de ADN.

Hemos utilizado el procedimiento descrito anteriormente para identificar sitios de replicación tardíos en levadura de florecimiento. Prueba este planteamiento con una región de replicación finales conocida en un cromosoma artificial demostró la técnica exacta y fiable. Nuestros resultados también han demostrado la importancia biológica de la oportuna terminación de la replicación, mostrando que una región replicación tardía en el cromosoma 7, que identificamos como replicaci?...

Watch this Scientific Journal Video about G2-seq: A High Throughput Sequencing-based Technique for Identifying Late Replicating Regions of the Genome at JoVE.com

G2-seq: A High Throughput Sequencing-based Technique for Identifying Late Replicating Regions of the Genome

G2-seq: Una alto rendimiento basado en la secuencia técnica para identificar replicación tardía de regiones del genoma

Describimos una técnica para combinar la citometría de flujo y la secuenciación de alto rendimiento para identificar regiones finales replicación del genoma.

Numerous techniques have been developed to follow the progress of DNA replication through the S phase of the cell cycle. Most of these techniques have ...

g2-seq-high-throughput-sequencing-based-technique-for-identifying

Research

JoVE Journal

Genetics

5.7K vistas.  Fred Hutchinson Cancer Research Center. Describimos una técnica para combinar la citometría de flujo y la secuenciación de alto rendimiento para identificar regiones finales replicación del genoma.

Video: G2-seq: A High Throughput Sequencing-based Technique for Identifying Late Replicating Regions of the Genome

A Robotic Platform for High-throughput Protoplast Isolation and Transformation

Over the last decade there has been a resurgence in the use of plant protoplasts that range from model species to crop species, for analysis of signal transduction pathways, transcriptional regulatory networks, gene expression, genome-editing, and gene-silencing. Furthermore, significant progress has been made in the regeneration of plants from protoplasts, which has generated even more interest in the use of these systems for plant genomics. In this work, a protocol has been developed for automation of protoplast isolation and transformation from a &#39;Bright Yellow&#39; 2 (BY-2) tobacco suspension culture using a robotic platform. The transformation procedures were validated using an orange fluorescent protein (OFP) reporter gene (pporRFP) under the control of the Cauliflower mosaic virus 35S promoter (35S). OFP expression in protoplasts was confirmed by epifluorescence microscopy. Analyses also included protoplast production efficiency methods using propidium iodide. Finally, low-cost food-grade enzymes were used for the protoplast isolation procedure, circumventing the need for lab-grade enzymes that are cost-prohibitive in high-throughput automated protoplast isolation and analysis. Based on the protocol developed in this work, the complete procedure from protoplast isolation to transformation can be conducted in under 4 hr, without any input from the operator. While the protocol developed in this work was validated with the BY-2 cell culture, the procedures and methods should be translatable to any plant suspension culture/protoplast system, which should enable acceleration of crop genomics research.

A high-throughput, automated, tobacco protoplast production and transformation methodology is described. The robotic system enables massively parallel gene expression and discovery in the model BY-2 system that should be translatable to non-model crops.

Una plataforma robótica para de alto rendimiento de protoplastos aislamiento y Transformación

Over the last decade there has been a resurgence in the use of plant protoplasts that range from model species to crop species, for analysis of signal ...

Investigación

Genética

Mapping RNA-RNA Interactions Globally Using Biotinylated Psoralen

Knowing how RNAs interact with themselves and with others is key to understanding RNA based gene regulation in the cell. While examples of RNA-RNA interactions such as microRNA-mRNA interactions have been shown to regulate gene expression, the full extent to which RNA interactions occur in the cell is still unknown. Previous methods to study RNA interactions have primarily focused on subsets of RNAs that are interacting with a particular protein or RNA species. Here, we detail a method named Sequencing of Psoralen crosslinked, Ligated, and Selected Hybrids (SPLASH) that allows genome-wide capture of RNA interactions in vivo in an unbiased manner. SPLASH utilizes in vivo crosslinking, proximity ligation, and high throughput sequencing to identify intramolecular and intermolecular RNA base-pairing partners globally. SPLASH can be applied to different organisms including bacteria, yeast and human cells, as well as diverse cellular conditions to facilitate the understanding of the dynamics of RNA organization under diverse cellular contexts. The entire experimental SPLASH protocol takes about 5 days to complete and the computational workflow takes about 7 days to complete.

Here, we detail the method of Sequencing of Psoralen crosslinked, Ligated, and Selected Hybrids (SPLASH), which enables genome-wide mapping of intramolecular and intermolecular RNA-RNA interactions in vivo. SPLASH can be applied to study RNA interactomes of organisms including yeast, bacteria and humans.

Mapeo de las interacciones RNA-ARN a nivel mundial usando Psoralen Biotinilado

Knowing how RNAs interact with themselves and with others is key to understanding RNA based gene regulation in the cell. While examples of RNA-RNA ...

Retroviral Scanning: Mapping MLV Integration Sites to Define Cell-specific Regulatory Regions

Moloney murine leukemia (MLV) virus-based retroviral vectors integrate predominantly in acetylated enhancers and promoters. For this reason, mLV integration sites can be used as functional markers of active regulatory elements. Here, we present a retroviral scanning tool, which allows the genome-wide identification of cell-specific enhancers and promoters. Briefly, the target cell population is transduced with an mLV-derived vector and genomic DNA is digested with a frequently cutting restriction enzyme. After ligation of genomic fragments with a compatible DNA linker, linker-mediated polymerase chain reaction (LM-PCR) allows the amplification of the virus-host genome junctions. Massive sequencing of the amplicons is used to define the mLV integration profile genome-wide. Finally, clusters of recurrent integrations are defined to identify cell-specific regulatory regions, responsible for the activation of cell-type specific transcriptional programs.
The retroviral scanning tool allows the genome-wide identification of cell-specific promoters and enhancers in prospectively isolated target cell populations. Notably, retroviral scanning represents an instrumental technique for the retrospective identification of rare populations (e.g. somatic stem cells) that lack robust markers for prospective isolation.

Here, we describe a protocol for genome-wide mapping of the integration sites of Moloney murine leukemia virus-based retroviral vectors in human cells.

Escaneo Retroviral: Mapeo de sitios de integración MLV para definir regiones reguladoras específicas de células

Moloney murine leukemia (MLV) virus-based retroviral vectors integrate predominantly in acetylated enhancers and promoters. For this reason, mLV ...

Generation of Native Chromatin Immunoprecipitation Sequencing Libraries for Nucleosome Density Analysis

We present a modified native chromatin immunoprecipitation sequencing (ChIP-seq) experimental protocol compatible with a Gaussian mixture distribution based analysis methodology (nucleosome density ChIP-seq; ndChIP-seq) that enables the generation of combined measurements of micrococcal nuclease (MNase) accessibility with histone modification genome-wide. Nucleosome position and local density, and the posttranslational modification of their histone subunits, act in concert to regulate local transcription states. Combinatorial measurements of nucleosome accessibility with histone modification generated by ndChIP-seq allows for the simultaneous interrogation of these features. The ndChIP-seq methodology is applicable to small numbers of primary cells inaccessible to cross-linking based ChIP-seq protocols. Taken together, ndChIP-seq enables the measurement of histone modification in combination with local nucleosome density to obtain new insights into shared mechanisms that regulate RNA transcription within rare primary cell populations.

We present a modified native chromatin immunoprecipitation sequencing (ChIP-seq) methodology for the generation of sequence datasets suitable for a nucleosome density ChIP-seq analytical framework integrating micrococcal nuclease (MNase) accessibility with histone modification measurements.

Generación de inmunoprecipitación de la cromatina nativa secuenciación bibliotecas para el análisis de densidad de nucleosoma

We present a modified native chromatin immunoprecipitation sequencing (ChIP-seq) experimental protocol compatible with a Gaussian mixture distribution ...

Robust DNA Isolation and High-throughput Sequencing Library Construction for Herbarium Specimens

Herbaria are an invaluable source of plant material that can be used in a variety of biological studies. The use of herbarium specimens is associated with a number of challenges including sample preservation quality, degraded DNA, and destructive sampling of rare specimens. In order to more effectively use herbarium material in large sequencing projects, a dependable and scalable method of DNA isolation and library preparation is needed. This paper demonstrates a robust, beginning-to-end protocol for DNA isolation and high-throughput library construction from herbarium specimens that does not require modification for individual samples. This protocol is tailored for low quality dried plant material and takes advantage of existing methods by optimizing tissue grinding, modifying library size selection, and introducing an optional reamplification step for low yield libraries. Reamplification of low yield DNA libraries can rescue samples derived from irreplaceable and potentially valuable herbarium specimens, negating the need for additional destructive sampling and without introducing discernible sequencing bias for common phylogenetic applications. The protocol has been tested on hundreds of grass species, but is expected to be adaptable for use in other plant lineages after verification. This protocol can be limited by extremely degraded DNA, where fragments do not exist in the desired size range, and by secondary metabolites present in some plant material that inhibit clean DNA isolation. Overall, this protocol introduces a fast and comprehensive method that allows for DNA isolation and library preparation of 24 samples in less than 13 h, with only 8 h of active hands-on time with minimal modifications.

This article demonstrates a detailed protocol for DNA isolation and high-throughput sequencing library construction from herbarium material including rescue of exceptionally poor-quality DNA.

Robusto de ADN y la secuenciación de alto rendimiento biblioteca construcción de especímenes de herbario

Herbaria are an invaluable source of plant material that can be used in a variety of biological studies. The use of herbarium specimens is associated with ...

Embryo Microinjection and Transplantation Technique for Nasonia vitripennis Genome Manipulation

The jewel wasp Nasonia vitripennis has emerged as an effective model system for the study of processes including sex determination, haplo-diploid sex determination, venom synthesis, and host-symbiont interactions, among others. A major limitation of working with this organism is the lack of effective protocols to perform directed genome modifications. An important part of genome modification is delivery of editing reagents, including CRISPR/Cas9 molecules, into embryos through microinjection. While microinjection is well established in many model organisms, this technique is particularly challenging to perform in N. vitripennis primarily due to its small embryo size, and the fact that embryonic development occurs entirely within a parasitized blowfly pupa. The following procedure overcomes these significant challenges while demonstrating a streamlined, visual procedure for effectively removing wasp embryos from parasitized host pupae, microinjecting them, and carefully transplanting them back into the host for continuation and completion of development. This protocol will strongly enhance the capability of research groups to perform advanced genome modifications in this organism.

Embryo Microinjection and Transplantation Technique for Nasonia vitripennis Genome Manipulation

Microinjection of Nasonia vitripennis embryos is an essential method for generating heritable genome modifications. Described here is a detailed procedure for microinjection and transplantation of Nasonia vitripennis embryos, which will greatly facilitate future genome manipulation in this organism.

Microinyección de embriones y la técnica de trasplante para la manipulación del genoma de Nasonia vitripennis

The jewel wasp Nasonia vitripennis has emerged as an effective model system for the study of processes including sex determination, haplo-diploid sex ...

High-throughput Identification of Synergistic Drug Combinations by the Overlap2 Method

Although antimicrobial drugs have dramatically increased the lifespan and quality of life in the 20th century, antimicrobial resistance threatens our entire society's ability to treat systemic infections. In the United States alone, antibiotic-resistant infections kill approximately 23,000 people a year and cost around 20 billion USD in additional healthcare. One approach to combat antimicrobial resistance is combination therapy, which is particularly useful in the critical early stage of infection, before the infecting organism and its drug resistance profile have been identified. Many antimicrobial treatments use combination therapies. However, most of these combinations are additive, meaning that the combined efficacy is the same as the sum of the individual antibiotic efficacy. Some combination therapies are synergistic: the combined efficacy is much greater than additive. Synergistic combinations are particularly useful because they can inhibit the growth of antimicrobial drug resistant strains. However, these combinations are rare and difficult to identify. This is due to the sheer number of molecules needed to be tested in a pairwise manner: a library of 1,000 molecules has 1 million potential combinations. Thus, efforts have been made to predict molecules for synergy. This article describes our high-throughput method for predicting synergistic small molecule pairs known as the Overlap2 Method (O2M). O2M uses patterns from chemical-genetic datasets to identify mutants that are hypersensitive to each molecule in a synergistic pair but not to other molecules. The Brown lab exploits this growth difference by performing a high-throughput screen for molecules that inhibit the growth of mutant but not wild-type cells. The lab's work previously identified molecules that synergize with the antibiotic trimethoprim and the antifungal drug fluconazole using this strategy. Here, the authors present a method to screen for novel synergistic combinations, which can be altered for multiple microorganisms.

High-throughput Identification of Synergistic Drug Combinations by the Overlap2 Method

Synergistic drug combinations are difficult and time-consuming to identify empirically. Here, we describe a method for identifying and validating synergistic small molecules.

Alto rendimiento identificación de combinaciones de fármacos sinérgicos por el método de superposición2

Although antimicrobial drugs have dramatically increased the lifespan and quality of life in the 20th century, antimicrobial resistance threatens our ...

Promoter Capture Hi-C: High-resolution, Genome-wide Profiling of Promoter Interactions

The three-dimensional organization of the genome is linked to its function. For example, regulatory elements such as transcriptional enhancers control the spatio-temporal expression of their target genes through physical contact, often bridging considerable (in some cases hundreds of kilobases) genomic distances and bypassing nearby genes. The human genome harbors an estimated one million enhancers, the vast majority of which have unknown gene targets. Assigning distal regulatory regions to their target genes is thus crucial to understand gene expression control. We developed Promoter Capture Hi-C (PCHi-C) to enable the genome-wide detection of distal promoter-interacting regions (PIRs), for all promoters in a single experiment. In PCHi-C, highly complex Hi-C libraries are specifically enriched for promoter sequences through in-solution hybrid selection with thousands of biotinylated RNA baits complementary to the ends of all promoter-containing restriction fragments. The aim is to then pull-down promoter sequences and their frequent interaction partners such as enhancers and other potential regulatory elements. After high-throughput paired-end sequencing, a statistical test is applied to each promoter-ligated restriction fragment to identify significant PIRs at the restriction fragment level. We have used PCHi-C to generate an atlas of long-range promoter interactions in dozens of human and mouse cell types. These promoter interactome maps have contributed to a greater understanding of mammalian gene expression control by assigning putative regulatory regions to their target genes and revealing preferential spatial promoter-promoter interaction networks. This information also has high relevance to understanding human genetic disease and the identification of potential disease genes, by linking non-coding disease-associated sequence variants in or near control sequences to their target genes.

DNA regulatory elements, such as enhancers, control gene expression by physically contacting target gene promoters, often through long-range chromosomal interactions spanning large genomic distances. Promoter Capture Hi-C (PCHi-C) identifies significant interactions between promoters and distal regions, enabling the assignment of potential regulatory sequences to their target genes.

Promotor captura Hola-C: Perfiles de alta resolución, genoma de interacciones promotor

The three-dimensional organization of the genome is linked to its function. For example, regulatory elements such as transcriptional enhancers control the ...

High-throughput Identification of Gene Regulatory Sequences Using Next-generation Sequencing of Circular Chromosome Conformation Capture (4C-seq)

The identification of regulatory elements for a given target gene poses a significant technical challenge owing to the variability in the positioning and effect sizes of regulatory elements to a target gene. Some progress has been made with the bioinformatic prediction of the existence and function of proximal epigenetic modifications associated with activated gene expression using conserved transcription factor binding sites. Chromatin conformation capture studies have revolutionized our ability to discover physical chromatin contacts between sequences and even within an entire genome. Circular chromatin conformation capture coupled with next-generation sequencing (4C-seq), in particular, is designed to discover all possible physical chromatin interactions for a given sequence of interest (viewpoint), such as a target gene or a regulatory enhancer. Current 4C-seq strategies directly sequence from within the viewpoint but require numerous and diverse viewpoints to be simultaneously sequenced to avoid the technical challenges of uniform base calling (imaging) with next generation sequencing platforms. This volume of experiments may not be practical for many laboratories. Here, we report a modified approach to the 4C-seq protocol that incorporates both an additional restriction enzyme digest and qPCR-based amplification steps that are designed to facilitate a greater capture of diverse sequence reads and mitigate the potential for PCR bias, respectively. Our modified 4C method is amenable to the standard molecular biology lab for assessing chromatin architecture.

High-throughput Identification of Gene Regulatory Sequences Using Next-generation Sequencing of Circular Chromosome Conformation Capture 4C-seq

The identification of physical interactions between genes and regulatory elements is challenging but has been facilitated by chromosome conformation capture methods. This modification to the 4C-seq protocol mitigates PCR bias by minimizing over-amplification of PCR templates and maximizes the mappability of reads by incorporating an addition restriction enzyme digest step.

Captura de alto rendimiento identificación de secuencias reguladoras de genes utilizando secuenciación de próxima generación de conformación Circular cromosoma (4C-seq)

The identification of regulatory elements for a given target gene poses a significant technical challenge owing to the variability in the positioning and ...

CRISPR-mediated Genome Editing of the Human Fungal Pathogen Candida albicans

This method describes the efficient CRISPR mediated genome editing of the diploid human fungal pathogen Candida albicans. CRISPR-mediated genome editing in C. albicans requires Cas9, guide RNA, and repair template. A plasmid expressing a yeast codon optimized Cas9 (CaCas9) has been generated. Guide sequences directly upstream from a PAM site (NGG) are cloned into the Cas9 expression vector. A repair template is then made by primer extension in vitro. Cotransformation of the repair template and vector into C. albicans leads to genome editing. Depending on the repair template used, the investigator can introduce nucleotide changes, insertions, or deletions. As C. albicans is a diploid, mutations are made in both alleles of a gene, provided that the A and B alleles do not harbor SNPs that interfere with guide targeting or repair template incorporation. Multimember gene families can be edited in parallel if suitable conserved sequences exist in all family members. The C. albicans CRISPR system described is flanked by FRT sites and encodes flippase. Upon induction of flippase, the antibiotic marker (CaCas9) and guide RNA are removed from the genome. This allows the investigator to perform subsequent edits to the genome. C. albicans CRISPR is a powerful fungal genetic engineering tool, and minor alterations to the described protocols permit the modification of other fungal species including C. glabrata, N. castellii, and S. cerevisiae.

CRISPR-mediated Genome Editing of the Human Fungal Pathogen Candida albicans

Efficient genome engineering of Candida albicans is critical to understanding the pathogenesis and development of therapeutics. Here, we described a protocol to quickly and accurately edit the C. albicans genome using CRISPR. The protocol allows investigators to introduce a wide variety of genetic modifications including point mutations, insertions, and deletions.

Edición del genoma mediada por CRISPR el hongo patógeno Candida albicans

This method describes the efficient CRISPR mediated genome editing of the diploid human fungal pathogen Candida albicans. CRISPR-mediated genome editing ...