We gratefully thank the DFG for financial support (HO 1779/21-1) as well as Katrin Kumke and Dr. Veit Schubert (IPK, Gatersleben) for technical advice.

1. Cromosoma Preparación <ol><li> La germinación de semillas y fijación de puntas de las raíces <ol><li> 10-20 germinar semillas de cebada en dos capas de papel de filtro húmedo en una placa de Petri bajo condiciones de oscuridad durante 2 días a 22-24 ° C. Cortar las raíces vigorosas con la longitud de 1-2 cm de la semilla mediante el uso de una cuchilla de afeitar. </li><li> Preparar agua helada mediante la colocación de una botella de vidrio de 500 ml que contiene agua fría del grifo en agua con hielo picado. Airear el agua helada y se sumerja puntas de las raíces durante 20 horas para aumentar la frecuencia de las células en metafase. </li><li> Transferencia de raíces a partir de agua a 50 ml de etanol: ácido acético (3: 1) fijador para fijarlos a TA durante 2 días. Raíces Almacenar en etanol recién preparada: ácido acético (3: 1) fijador a 4 ° C hasta su uso hasta un año. </li></ol></li><li> Tratamiento de lavado y la enzima <ol><li> Lávese las 10-20 raíces con agua corriente helada 30 ml durante 5 minutos dos veces usando un vaso de precipitados de vidrio de 50 ml. Utilice microscopio binocular. Transferencia raíces uno por uno en30 ml 0,01 M tampón citrato (0,01 M de ácido cítrico + 0,01 M de citrato de sodio, pH 4,8) utilizando pinzas y lavar agitando el vaso de vidrio durante 5 minutos dos veces. Coloque raíces sobre papel de filtro para eliminar el líquido por completo y de corte de tejido no meristemática no deseado usando una cuchilla de afeitar. </li><li> Incubar hasta 20 puntas de las raíces en la mezcla de enzima 1 ml a 37 ° C durante aproximadamente 50 min para suavizar el tejido de la planta (Tabla 1) en un vidrio de reloj. Mezcla de enzimas contiene 0,7% R10 celulasa, 0,7% de celulasa, pectoliasa 1% y 1% citohelicasa diluido en tampón de citrato 0,01 M. Almacenar la mezcla de enzimas a -20 ° C y reutilizada hasta cinco veces. </li><li> Retire la enzima con la pipeta y lavar las puntas de las raíces en el hielo con 5 ml de 0,01 M tampón citrato dos veces para reemplazar la enzima residual. </li></ol></li><li> Maceración Root <ol><li> Puntas de las raíces de lavado con 1 ml de etanol al 96% dos veces cuidadosamente en el mismo vidrio de reloj. Reemplazar con etanol recién preparada fijador (75% ácido acético: etanol 25%). Utilice 10-15fijador l por punta de la raíz. </li><li> Puntas de las raíces de transferencia junto con el fijador en un tubo de 2 ml y se desintegran meristemos radiculares con una aguja o unas pinzas de disección. Toca el tubo 20 veces para resuspender las células para obtener una suspensión celular. Guarde la suspensión de células a -20 ° C hasta dos meses. </li></ol></li><li> Dropping de la suspensión celular <ol><li> Coloca 2-3 capas de tejido de papel empapada en agua en una placa caliente a 50 ° C. Sumerja diapositivas microscópicas en el agua del grifo helado en la nevera durante 30 minutos. Y el lugar se desliza en la parte superior del tejido de papel húmeda. </li><li> Pipeta 7-10 l de suspensión celular y colóquelo a una distancia de 20 cm sobre el portaobjetos enfriado colocado en el plato caliente. Pipeta 10 l de mezcla de ácido acético-etanol en el mismo lugar que la suspensión de células en la diapositiva y mantener la diapositiva en el plato caliente durante otros 2 min. Colocar el portaobjetos en el plato caliente sin el tejido húmedo y deje que se seque durante 1 min. </li></ol></li><li> Control de calidad y storage de diapositivas <ol><li> Compruebe diapositivas utilizando un microscopio de contraste de fase para controlar la calidad de la difusión cromosoma. Utilice diapositivas o bien el mismo día o tienda por inmersión en etanol al 96% en un tarro Coplin a -20 ° C. </li></ol></li><li> Pretratamiento de diapositivas antes de FISH; todos los pasos se llevaron a cabo a RT <ol><li> Colocar los portaobjetos en un tarro de Coplin que contiene 50 ml de 2x SSC (20x SSC contiene 3 M NaCl y 300 mM de citrato trisódico) durante 5 min. Con unas pinzas, toboganes de transferencia a un tarro de Coplin que contiene 50 ml de ácido acético 45% para 3 a 10 min. </li><li> Transferencia desliza a un frasco de Coplin que contiene 50 ml de 2x SSC durante 10 minutos. Diapositivas de transferencia a un frasco Coplin que contiene 50 ml de formaldehído al 4% (en 2x SSC) y sumergirse diapositivas durante 10 minutos para fijar los cromosomas. </li><li> Retire formaldehído enjuagando las diapositivas 3 veces durante 4 minutos cada uno, en una jarra Coplin que contiene 50 ml 2x SSC. Deshidratar las diapositivas en una jarra Coplin durante 2 minutos en serie de 70%, 90% y etanol al 100%, respectivamente, y se desliza en seco en una línea verticalposición. </li></ol></li></ol> 2. fluorescente hibridación in situ (FISH) <ol><li> Para cada diapositiva, preparar una solución de hibridación de 20 l en total utilizando 10 l de formamida desionizada, 5 l de tampón de hibridación 4x (200 l de tampón contiene 80 l de 20x SSC, 8 l 1 M Tris-HCl pH 8,0, 1,6 l 0,5 M EDTA, 11,2 l 10 g / l de esperma de salmón y 99,2 l de DNasa libre de agua), 3 l de la sonda y 2 l de agua libre de DNasa. </li><li> Añadir 20 l de solución de hibridación por diapositiva y la tapa con un cubreobjetos de 24 x 32 mm y arrestar a la hoja de la cubierta con cemento de goma. Desnaturalizar diapositivas con sondas simultáneamente a 80 ° C durante 2 minutos en un plato caliente. </li><li> Transferencia desliza a una cámara húmeda e incubar diapositivas a 37 ° CO / N luz evitando. Retire cubreobjetos enjuagando las diapositivas en un frasco Coplin con 2x SSC. Colocar los portaobjetos en un tarro de Coplin que contiene 55 a 60 ° C 2x SSC y se incuban durante 20 min. </li><li> Colocar los portaobjetos a 2x SSC en un frasco Coplin durante 2 minutos a temperatura ambiente. Deshidratar portaobjetos en un tarro Coplin durante 2 minutos en serie de 70%, 90% y 100% de etanol, respectivamente. </li><li> Seque las diapositivas y de contraste con 1 mg / ml 4 &#39;, 6-diamidino-2-phenylindoline (DAPI) en antifade medio de montaje, evitar la luz intensa. </li></ol> 3. Análisis microscópico y almacenamiento <ol><li> Analizar las diapositivas utilizando un microscopio de epifluorescencia. La selección de filtro depende de la fluorocromo utilizado para el marcaje de la sonda. Si es necesario, almacenar diapositivas a 4 ° C en condiciones de oscuridad hasta un año. </li></ol>

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	<li>Geber, G., Schweizer, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cytochemical+heterochromatin+differentiation+in+Sinapis+alba+(Cruciferae)+using+a+simple+air-drying+technique+for+producing+chromosome+spreads.">Cytochemical heterochromatin differentiation in Sinapis alba (Cruciferae) using a simple air-drying technique for producing chromosome spreads.</a> Pl Syst Evol. 158 (2-4), 97-106 (1988).</li><li>Andras, S. C., 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=A+drop-spreading+technique+to+produce+cytoplasm-free+mitotic+preparations+from+plants+with+small+chromosomes.">A drop-spreading technique to produce cytoplasm-free mitotic preparations from plants with small chromosomes.</a> Chromosome Res. 7 (8), 641-647 (1999).</li><li>Rothfels, K. H., Siminovitch, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+air-drying+technique+for+flattening+chromosomes+in+mammalian+cells+grown+in+vitro.">An air-drying technique for flattening chromosomes in mammalian cells grown in vitro.</a> Stain Technology. 33 (2), 73-77 (1958).</li><li>Martin, R., Busch, W., Herrmann, R. G., Wanner, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Efficient+preparation+of+plant+chromosomes+for+high-resolution+scanning+electron+microscopy.">Efficient preparation of plant chromosomes for high-resolution scanning electron microscopy.</a> Chromosome Res. 2 (5), 411-415 (1994).</li><li>Kato, A., Albert, P. S., Vega, J. M., Birchler, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sensitive+fluorescence+in+situ+hybridization+signal+detection+in+maize+using+directly+labeled+probes+produced+by+high+concentration+DNA+polymerase+nick+translation.">Sensitive fluorescence in situ hybridization signal detection in maize using directly labeled probes produced by high concentration DNA polymerase nick translation.</a> Biotech. Histochem. 81 (2-3), 71-78 (2006).</li><li>Kirov, I., Divashuk, M., Van Laere, K., Soloviev, A., Khrustaleva, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+easy+'SteamDrop'+method+for+high+quality+plant+chromosome+preparation.">An easy 'SteamDrop' method for high quality plant chromosome preparation.</a> Mol. Cytogenet. 7, 21 (2014).</li><li>Spurbeck, J. L., Zinsmeister, A. R., Meyer, K. J., Jalal, S. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dynamics+of+chromosome+spreading.">Dynamics of chromosome spreading.</a> Am J Med Genet. 61 (4), 387-393 (1996).</li><li>Ma, 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=Synteny+between+Brachypodium+distachyon+and+Hordeum+vulgare+as+revealed+by+FISH.">Synteny between Brachypodium distachyon and Hordeum vulgare as revealed by FISH.</a> Chromosome Res. 18 (7), 841-850 (2010).</li><li>Kato, A., Lamb, J. C., Birchler, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chromosome+painting+using+repetitive+DNA+sequences+as+probes+for+somatic+chromosome+identification+in+maize.">Chromosome painting using repetitive DNA sequences as probes for somatic chromosome identification in maize.</a> Proc. Natl. Acad. Sci. U S A. 101 (37), 13554-13559 (2004).</li><li>Pan, W. H., Houben, A., Schlegel, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Highly+effective+cell+synchronization+in+plant-roots+by+hydroxyurea+and+amiprophos-methyl+or+colchicine.">Highly effective cell synchronization in plant-roots by hydroxyurea and amiprophos-methyl or colchicine.</a> Genome. 36 (2), 387-390 (1993).</li><li>Kim, J. S., 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=Integrated+karyotyping+of+sorghum+by+in+situ+hybridization+of+landed+BACs.">Integrated karyotyping of sorghum by in situ hybridization of landed BACs.</a> Genome. 45 (2), 402-412 (2002).</li><li>Lapitan, N. L. V., Brown, S. E., Kennard, W., Stephens, J. L., Knudson, D. 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The authors have nothing to disclose.

El experimento preparación cromosoma se ha llevado a cabo utilizando las raíces jóvenes de cereales pertenecientes a la familia de las gramíneas (Poaceae). Todas las especies analizadas tienen 14 cromosomas en metafase relativamente largo mitótico (11 a 15 micras) en el conjunto del genoma diploide y pertenecen a especies de gran genoma (05.01 a 07.09 GBP). Longitud de raíces germinadas no era más de 2 cm para obtener un máximo de tejido meristemático. La sincronización de las cél...

Hibridación in situ fluorescente (FISH) es una herramienta eficaz para el mapeo físico de las secuencias de copia única y altas a nivel cromosómico. Requisito previo es la preparación de extensiones de cromosomas de alta calidad. No hay cromosoma protocolo general de preparación que sería igualmente adecuado para células animales y vegetales. Preparación de cromosomas de la planta es particularmente difícil debido a la pared celular rígida y varios consistencia citoplasma dentro de diferentes especies. Uno de los métodos favorables para la preparación de cromosomas de la planta es una técnica de caída de llamada también conocida como técnica de la gota de dispersión y secado al aire técnica de 1,2. Este método fue introducido por primera vez en 1958 por Rothfels y Siminovitch para in vitro células de mamíferos cultivadas 3. Más tarde Martin et al., 4 y Kato et al. 5 adaptó este método para las plantas. Más recientemente, un método llamado &#39;SteamDrop y# 39; fue desarrollado que utiliza vapor de agua para la preparación de cromosomas que no se solapan 6. Aunque, se observó la influencia positiva de la alta humedad anterior 7, &#39;SteamDrop&#39; ofrece un flujo de trabajo controlado de preparaciones de cromosomas de alta calidad 6. El tratamiento de vapor provoca el estiramiento de los cromosomas probablemente conectados a algunas modificaciones de las proteínas cromosómicas. La calidad de los diferenciales de metafase resultante es muy alta, aunque de retención de número suficiente de metafase completa se extiende para posteriores experimentos de FISH exige conocimientos técnicos. Aquí se presenta un protocolo para la preparación de los cromosomas mitóticos cereales adecuados para la detección de sondas FISH individuales y alta copia 5,8. Este método es una variante mejorada del método de goteo se seque al aire descrito por Kato 9 realizado bajo una humedad relativa de 50% -55% (Figura 1). Este protocolo comprende un número reducidode etapas de lavado que hace su aplicación fácil, eficiente y reproducible. El uso de este protocolo se obtuvieron extensiones de cromosomas de alta calidad y los resultados de FISH para Hordeum vulgare, H. bulbosum, H. marinum, H. murinum, H. pubiflorum y Secale cereale.

<table><tbody><tr><td>Hot Plate</td><td>MEDAX GmbH</td><td>12603</td><td></td></tr><tr><td>Cellulase R10</td><td>Duchefa</td><td>C8001</td><td></td></tr><tr><td>Cellulase&amp;nbsp;</td><td>CalBioChem</td><td>219466</td><td></td></tr><tr><td>Pectolyase</td><td>Sigma</td><td>P3026</td><td></td></tr><tr><td>Cytohelicase</td><td>Sigma</td><td>C8274</td><td></td></tr><tr><td>Texas Red-12-dUTP</td><td>Invitrogen</td><td>C3176</td><td>direct fluorochrome&amp;nbsp;</td></tr><tr><td>Fluor488-5-dUTP</td><td>Invitrogen</td><td>C11397</td><td>direct fluorochrome&amp;nbsp;</td></tr><tr><td>Fluorecsence microscope</td><td>Olympus BX61</td><td>BX61</td><td></td></tr><tr><td>CCD camera</td><td>Orca ER, Hamamatsu</td><td>C10600</td><td></td></tr><tr><td>4&amp;rsquo;,6-diamidino-2-phenylindole (DAPI)&amp;nbsp;</td><td>Vector Laboratories</td><td>H-1200</td><td>fluorecsent dye</td></tr></tbody></table>

a fast air-dry dropping chromosome preparation method suitable for fish in plants

Preparación de extensiones de cromosomas es un requisito previo para el buen desarrollo de la hibridación in situ fluorescente (FISH). Preparación de alta calidad extensiones de cromosomas planta es un reto debido a la pared celular rígida. Uno de los métodos aprobados para la preparación de cromosomas de la planta es una preparación gota llamada, también conocido como gota de dispersión o la técnica de secado al aire. A continuación, presentamos un protocolo para la preparación rápida del cromosoma mitótico extiende adecuado para la detección FISH de sondas de ADN individuales y altos de copia. Este método es una variante mejorada del método de la gota de secado al aire se realiza bajo una humedad relativa de 50% -55%. Este protocolo se compone de un número reducido de etapas de lavado que hace su aplicación fácil, eficiente y reproducible. Obvios beneficios de este enfoque son bien extendidas, metafase los cromosomas intactos y numerosos que sirven como requisito previo perfecto para el análisis FISH éxito. El uso de este protocolo se obtuvo chrom de alta calidadOsome márgenes y resultados de FISH reproducibles para Hordeum vulgare, H. bulbosum, H. marinum, H. murinum, H. pubiflorum y Secale cereale.

Diapositivas microscópica con los diferenciales en metafase de la mitosis se prepararon por el método de preparación rápida secar al aire el cromosoma de goteo descrita anteriormente (Suppl. Figura 1). FISH análisis se llevó a cabo utilizando tanto, secuencias repetitivas y de una sola copia. Las imágenes se obtuvieron por un microscopio de epifluorescencia con un conjunto de filtros que permite la excitación de los fluoróforos correspondientes y capturados por una cámara CCD monocromo de alta...

Watch this Scientific Journal Video about A Fast Air-dry Dropping Chromosome Preparation Method Suitable for FISH in Plants at JoVE.com

A Fast Air-dry Dropping Chromosome Preparation Method Suitable for FISH in Plants

A protocol is described for the preparation of high-quality mitotic plant chromosome spreads by a fast air-dry dropping method suitable for the FISH detection of single and high copy DNA probes.

Una caída Cromosoma Aire seco Rápido Método de preparación adecuados para FISH en Plantas

Preparation of chromosome spreads is a prerequisite for the successful performance of fluorescence in situ hybridization (FISH). Preparation of high ...

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Research

JoVE Journal

Biology

13.1K vistas.  Leibniz Institute of Plant Genetics and Crop Plant Research (IPK). A protocol is described for the preparation of high-quality mitotic plant chromosome spreads by a fast air-dry dropping method suitable for the FISH detection of single and high copy DNA probes.

Video: A Fast Air-dry Dropping Chromosome Preparation Method Suitable for FISH in Plants

Profiling DNA Replication Timing Using Zebrafish as an In Vivo Model System

DNA replication timing is an important cellular characteristic, exhibiting significant relationships with chromatin structure, transcription, and DNA mutation rates. Changes in replication timing occur during development and in cancer, but the role replication timing plays in development and disease is not known. Zebrafish were recently established as an in vivo model system to study replication timing. Here is detailed the protocols for using the zebrafish to determine DNA replication timing. After sorting cells from embryos and adult zebrafish, high-resolution genome-wide DNA replication timing patterns can be constructed by determining changes in DNA copy number through analysis of next generation sequencing data. The zebrafish model system allows for evaluation of the replication timing changes that occur in vivo throughout development, and can also be used to assess changes in individual cell types, disease models, or mutant lines. These methods will enable studies investigating the mechanisms and determinants of replication timing establishment and maintenance during development, the role replication timing plays in mutations and tumorigenesis, and the effects of perturbing replication timing on development and disease.

Profiling DNA Replication Timing Using Zebrafish as an In Vivo Model System

Zebrafish were recently used as an in vivo model system to study DNA replication timing during development. Here is detailed the protocols for using zebrafish embryos to profile replication timing. This protocol can be easily adapted to study replication timing in mutants, individual cell types, disease models, and other species.

Perfiles de sincronización de replicación de ADN utilizando el pez cebra como un sistema de modelo en Vivo

DNA replication timing is an important cellular characteristic, exhibiting significant relationships with chromatin structure, transcription, and DNA ...

Investigación

Genética

Preparation of Meiotic Chromosome Spreads from Zebrafish Spermatocytes

Meiosis is the key cellular process required to create haploid gametes for sexual reproduction. Model organisms have been instrumental in understanding the chromosome events that take place during meiotic prophase, including the pairing, synapsis, and recombination events that ensure proper chromosome segregation. While the mouse has been an important model for understanding the molecular mechanisms underlying these processes, not all meiotic events in this system are analogous to human meiosis. We recently demonstrated the exciting potential of the zebrafish as a model of human spermatogenesis. Here we describe, in detail, our methods to visualize meiotic chromosomes and associated proteins in chromosome spread preparations. These preparations have the advantage of allowing high resolution analysis of chromosome structures. First, we describe the procedure for dissecting testes from adult zebrafish, followed by cell dissociation, lysis, and spreading of the chromosomes. Next, we describe the procedure for detecting the localization of meiotic chromosome proteins, by immunofluorescence detection, and nucleic acid sequences, by fluorescence in situ hybridization (FISH). These techniques comprise a useful set of tools for the cytological analysis of meiotic chromatin architecture in the zebrafish system. Researchers in the zebrafish community should be able to quickly master these techniques and incorporate them into their standard analyses of reproductive function.

Nuclear surface spreads are an indispensable tool for studying chromosome events during meiosis. Here we demonstrate a method to prepare and visualize meiotic chromosomes during prophase I from zebrafish spermatocytes.

Preparación de las propagaciones del cromosoma meiótico a partir de espermacitos de peces cebra

Meiosis is the key cellular process required to create haploid gametes for sexual reproduction. Model organisms have been instrumental in understanding ...

Co-expression of Multiple Chimeric Fluorescent Fusion Proteins in an Efficient Way in Plants

Information about the spatiotemporal subcellular localization(s) of a protein is critical to understand its physiological functions in cells. Fluorescent proteins and generation of fluorescent fusion proteins have been wildly used as an effective tool to directly visualize the protein localization and dynamics in cells. It is especially useful to compare them with well-known organelle markers after co-expression with the protein of interest. Nevertheless, classical approaches for protein co-expression in plants usually involve multiple independent expression plasmids, and therefore have drawbacks that include low co-expression efficiency, expression-level variation, and high time expenditure in genetic crossing and screening. In this study, we describe a robust and novel method for co-expression of multiple chimeric fluorescent proteins in plants. It overcomes the limitations of the conventional methods by using a single expression vector that is composed of multiple semi-independent expressing cassettes. Each protein expression cassette contains its own functional protein expression elements, and therefore it can be flexibly adjusted to meet diverse expression demand. Also, it is easy and convenient to perform the assembly and manipulation of DNA fragments in the expression plasmid by using an optimized one-step reaction without additional digestion and ligation steps. Furthermore, it is fully compatible with current fluorescent protein derived bio-imaging technologies and applications, such as FRET and BiFC. As a validation of the method, we employed this new system to co-express fluorescently fused vacuolar sorting receptor and secretory carrier membrane proteins. The results show that their perspective subcellular localizations are the same as in previous studies by both transient expression and genetic transformation in plants.

We have developed a novel method for co-expressing multiple chimeric fluorescent fusion proteins in plants to overcome the difficulties of conventional methods. It takes advantage of using a single expression plasmid that contains multiple functionally independent protein expressing cassettes to achieve protein co-expression.

La expresión de múltiples proteínas de fusión quimérica de fluorescente de manera eficiente en las plantas

Information about the spatiotemporal subcellular localization(s) of a protein is critical to understand its physiological functions in cells. Fluorescent ...

Química

A High-Throughput Method For Zebrafish Sperm Cryopreservation and In Vitro Fertilization

This is a method for zebrafish sperm cryopreservation that is an adaptation of the Harvey method (Harvey et al., 1982).  We have introduced two changes to the original protocol that both streamline the procedure and increase sample uniformity.  First, we normalize all sperm volumes using freezing media that does not contain the cryoprotectant. Second, cryopreserved sperm are stored in cryovials instead of capillary tubes.  The rates of sperm freezing and thawing (&delta;&deg;C/time) are probably the two most critical variables to control in this procedure.  For this reason, do not substitute different tubes for those specified.  Working in teams of 2 it is possible to freeze the sperm of 100 males per team in ~2 hrs.  Sperm cryopreserved using this protocol has an average of 25% fertility (measured as the number of viable embryos generated in an in vitro fertilization divided by the total number of eggs fertilized) and this percent fertility is stable over many years.

A High-Throughput Method For Zebrafish Sperm Cryopreservation and In Vitro Fertilization

This is a high-throughput sperm cryopreservation protocol for zebrafish. Sperm cryopreserved using this protocol has an average of 25% fertility in subsequent vitro fertilization and is stable over many years.

Un método de alto rendimiento para la crioconservación de esperma de pez cebra y In Vitro Fertilización

This is a method for zebrafish sperm cryopreservation that is an adaptation of the Harvey method (Harvey et al., 1982).  We have introduced two changes to ...

Biología

Preparation of Drosophila Polytene Chromosome Squashes for Antibody Labeling

Drosophila has long been a favorite model system for studying the relationship between chromatin structure and gene regulation due to the cytological advantages provided by the giant salivary gland polytene chromosomes of third instar larvae.  In this tissue the chromosomes undergo many rounds of replication in the absence of cell division giving rise to approximately 1000 copies.  The DNA remains aligned after each replicative cycle resulting in greatly enlarged chromosomes that provide a unique opportunity to correlate chromatin morphology with the localization of specific proteins.  Consequently, there has been a high level of interest in defining the epigenetic modifications present at different genes and at different stages of the transcription process. An important tool for such studies is the labeling of polytene chromosomes with antibodies to the enzyme, transcription factor, or histone modification of interest. This video protocol illustrates the squash technique used in the Johansen laboratory to prepare Drosophila polytene chromosomes for antibody labeling.

This video protocol illustrates the squash technique used in the Johansen laboratory to prepare Drosophila polytene chromosomes for antibody labeling.

Preparación de los cromosomas politénicos de Drosophila Calabazas para el Etiquetado de anticuerpos

Drosophila has long been a favorite model system for studying the relationship between chromatin structure and gene regulation due to the cytological ...

Unravelling the Function of a Bacterial Effector from a Non-cultivable Plant Pathogen Using a Yeast Two-hybrid Screen

Unravelling the molecular mechanisms of disease manifestations is important to understand pathologies and symptom development in plant science. Bacteria have evolved different strategies to manipulate their host metabolism for their own benefit. This bacterial manipulation is often coupled with severe symptom development or the death of the affected plants. Determining the specific bacterial molecules responsible for the host manipulation has become an important field in microbiological research. After the identification of these bacterial molecules, called &#34;effectors,&#34; it is important to elucidate their function. A straightforward approach to determine the function of an effector is to identify its proteinaceous binding partner in its natural host via a yeast two-hybrid (Y2H) screen. Normally the host harbors numerous potential binding partners that cannot be predicted sufficiently by any in silico algorithm. It is thus the best choice to perform a screen with the hypothetical effector against a whole library of expressed host proteins. It is especially challenging if the causative agent is uncultivable like phytoplasma. This protocol provides step-by-step instructions for DNA purification from a phytoplasma-infected woody host plant, the amplification of the potential effector, and the subsequent identification of the plant&#39;s molecular interaction partner with a Y2H screen. Even though Y2H screens are commonly used, there is a trend to outsource this technique to biotech companies that offer the Y2H service at a cost. This protocol provides instructions on how to perform a Y2H in any decently equipped molecular biology laboratory using standard lab techniques.

Bacterial effector proteins are important for establishing successful infections. This protocol describes the experimental identification of proteinaceous binding partners of a bacterial effector protein in its natural plant host. Identifying these effector interactions via yeast two-hybrid screens has become an important tool in unravelling molecular pathogenicity strategies.

Desenredar la función de un efector bacteriana de una planta de patógenos no cultivables Uso de una levadura de dos híbridos pantalla

Unravelling the molecular mechanisms of disease manifestations is important to understand pathologies and symptom development in plant science. Bacteria ...

Inmunología e Infección

Chromosome Replicating Timing Combined with Fluorescent In situ Hybridization

Mammalian DNA replication initiates at multiple sites along chromosomes at different times during S phase, following a temporal replication program. The specification of replication timing is thought to be a dynamic process regulated by tissue-specific and developmental cues that are responsive to epigenetic modifications. However, the mechanisms regulating where and when DNA replication initiates along chromosomes remains poorly understood. Homologous chromosomes usually replicate synchronously, however there are notable exceptions to this rule. For example, in female mammalian cells one of the two X chromosomes becomes late replicating through a process known as X inactivation1. Along with this delay in replication timing, estimated to be 2-3 hr, the majority of genes become transcriptionally silenced on one X chromosome. In addition, a discrete cis-acting locus, known as the X inactivation center, regulates this X inactivation process, including the induction of delayed replication timing on the entire inactive X chromosome. In addition, certain chromosome rearrangements found in cancer cells and in cells exposed to ionizing radiation display a significant delay in replication timing of &gt;3 hours that affects the entire chromosome2,3. Recent work from our lab indicates that disruption of discrete cis-acting autosomal loci result in an extremely late replicating phenotype that affects the entire chromosome4. Additional 'chromosome engineering' studies indicate that certain chromosome rearrangements affecting many different chromosomes result in this abnormal replication-timing phenotype, suggesting that all mammalian chromosomes contain discrete cis-acting loci that control proper replication timing of individual chromosomes5.
Here, we present a method for the quantitative analysis of chromosome replication timing combined with fluorescent in situ hybridization. This method allows for a direct comparison of replication timing between homologous chromosomes within the same cell, and was adapted from6. In addition, this method allows for the unambiguous identification of chromosomal rearrangements that correlate with changes in replication timing that affect the entire chromosome. This method has advantages over recently developed high throughput micro-array or sequencing protocols that cannot distinguish between homologous alleles present on rearranged and un-rearranged chromosomes. In addition, because the method described here evaluates single cells, it can detect changes in chromosome replication timing on chromosomal rearrangements that are present in only a fraction of the cells in a population.

Chromosome Replicating Timing Combined with Fluorescent In situ Hybridization

A quantitative method for the analysis of chromosome replication timing is described. The method utilizes BrdU incorporation in combination with fluorescent in situ hybridization (FISH) to assess replication timing of mammalian chromosomes. This technique allows for the direct comparison of rearranged and un-rearranged chromosomes within the same cell.

Replicación del cromosoma Timing Combinado con fluorescente<em&gt; In situ</em&gt; La hibridación

Mammalian DNA replication initiates at multiple sites along chromosomes at different times during S phase, following a temporal replication program. The ...

Simple Method for Fluorescence DNA In Situ Hybridization to Squashed Chromosomes

DNA in situ hybridization (DNA ISH) is a commonly used method for mapping sequences to specific chromosome regions. This approach is particularly effective at mapping highly repetitive sequences to heterochromatic regions, where computational approaches face prohibitive challenges. Here we describe a streamlined protocol for DNA ISH that circumvents formamide washes that are standard steps in other DNA ISH protocols. Our protocol is optimized for hybridization with short single strand DNA probes that carry fluorescent dyes, which effectively mark repetitive DNA sequences within heterochromatic chromosomal regions across a number of different insect tissue types. However, applications may be extended to use with larger probes and visualization of single copy (non-repetitive) DNA sequences. We demonstrate this method by mapping several different repetitive sequences to squashed chromosomes from Drosophila melanogaster neural cells and Nasonia vitripennis spermatocytes. We show hybridization patterns for both small, commercially synthesized probes and for a larger probe for comparison. This procedure uses simple laboratory supplies and reagents, and is ideal for investigators who have little experience with performing DNA ISH.

Simple Method for Fluorescence DNA In Situ Hybridization to Squashed Chromosomes

Here, we present a simple method for performing fluorescence DNA in situ hybridization (DNA ISH) to visualize repetitive heterochromatic sequences on slide-mounted chromosomes. The method requires minimal reagents and it is versatile for use with short or long probes, different tissues, and detection with fluorescence or non-fluorescence-based signals.

Método simple de ADN de fluorescencia<em&gt; In Situ</em&gt; Hibridación a los cromosomas aplastado

DNA in situ hybridization (DNA ISH) is a commonly used method for mapping sequences to specific chromosome regions. This approach is particularly ...

Preparation of Prokaryotic and Eukaryotic Organisms Using Chemical Drying for Morphological Analysis in Scanning Electron Microscopy (SEM)

Scanning electron microscopy (SEM) is a widely available technique that has been applied to study biological specimens ranging from individual proteins to cells, tissues, organelles, and even whole organisms. This protocol focuses on two chemical drying methods, hexamethyldisilazane (HMDS) and t-butyl alcohol (TBA), and their application to imaging of both prokaryotic and eukaryotic organisms using SEM. In this article, we describe how to fix, wash, dehydrate, dry, mount, sputter coat, and image three types of organisms: cyanobacteria (Toxifilum mysidocida, Golenkina sp., and an unknown sp.), two euglenoids from the genus Monomorphina (M. aenigmatica and M. pseudopyrum), and the fruit fly (Drosophila melanogaster). The purpose of this protocol is to describe a fast, inexpensive, and simple method to obtain detailed information about the structure, size, and surface characteristics of specimens that can be broadly applied to a large range of organisms for morphological assessment. Successful completion of this protocol will allow others to use SEM to visualize samples by applying these techniques to their system.

Preparation of Prokaryotic and Eukaryotic Organisms Using Chemical Drying for Morphological Analysis in Scanning Electron Microscopy SEM

SEM analysis is an effective method to aid in species identification or phenotypic discrimination. This protocol describes the methods for examining specific morphological details of three representative types of organisms and would be broadly applicable to examining features of many organismal and tissue types.

Preparación de los organismos procarióticos y eucarióticos con secado químico para análisis morfológico en microscopía electrónica de barrido (SEM)

Scanning electron microscopy (SEM) is a widely available technique that has been applied to study biological specimens ranging from individual proteins to ...

Fluorescence In Situ Hybridization on DNA Halo Preparations to Reveal Whole Chromosomes, Telomeres and Gene Loci

The genome is associated with several structures inside cell nuclei, in order to regulate its activity and anchor it in specific locations. These structures are collectively known as the nucleoskeleton and include the nuclear lamina, the nucleoli, and nuclear bodies. Although many variants of fluorescence in situ hybridization (FISH) exist to study the genome and its organization, these are often limited by resolution and provide insufficient information on the genome&#39;s association with nuclear structures. The DNA halo method uses high salt concentrations and nonionic detergents to generate DNA loops that remain anchored to structures within nuclei through attachment regions within the genome. Here, soluble nuclear proteins, such as histones, lipids, and DNA not tightly bound to the nuclear matrix, are extracted. This leads to the formation of a halo of unattached DNA surrounding a residual nucleus which itself contains DNA closely associated with internal nuclear structures and extraction-resistant proteins. These extended DNA strands enable increased resolution and can facilitate physical mapping. In combination with FISH, this method has the added advantage of studying genomic interactions with all the structures that the genome is anchored by. This technique, termed HALO-FISH, is highly versatile whereby DNA halos can be coupled with nucleic acid probes to reveal gene loci, whole chromosomes, alpha satellite, telomeres and even RNA. This technique provides an insight into nuclear organization and function in normal&#160;cells and in disease progression such as with cancer.

Combining DNA halo preparations with fluorescence in situ hybridization enables high-resolution analysis of genomic interactions with the nucleoskeleton. Attached genome leads to hybridized fluorescent signals located within the residual extracted nuclei, whereas non-attached genome is in the halo of DNA surrounding the residual nuclei.

Una caída Cromosoma Aire seco Rápido Método de preparación adecuados para FISH en Plantas

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