Este trabajo fue financiado por los NIH Grant GM59354 a Sharon E. Bickel. Agradecemos Huy Nguyen p. asistencia en el desarrollo del protocolo para la generación de sondas fluorescentes brazo, Ann Lavanway ayuda con microscopía confocal y J. Emiliano Reed para asistencia técnica. También agradecemos a numerosos colegas de la comunidad de Drosophila para discusiones útiles y consejos.

<ol>
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B., 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=Disjunction+of+homologous+chromosomes+in+meiosis+I+depends+on+proteolytic+cleavage+of+the+meiotic+cohesin+Rec8+by+separin.">Disjunction of homologous chromosomes in meiosis I depends on proteolytic cleavage of the meiotic cohesin Rec8 by separin.</a> Cell. 103 (3), 387-398 (2000).</li><li>Bickel, S. E., Orr-Weaver, T., Balicky, E. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+sister-chromatid+cohesion+protein+ORD+is+required+for+chiasma+maintenance+in+Drosophila+oocytes.">The sister-chromatid cohesion protein ORD is required for chiasma maintenance in Drosophila oocytes.</a> Curr. Biol. 12 (11), 925-929 (2002).</li><li>Hodges, C. A., Revenkova, E., Jessberger, R., Hassold, T. J., Hunt, P. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=SMC1beta-deficient+female+mice+provide+evidence+that+cohesins+are+a+missing+link+in+age-related+nondisjunction.">SMC1beta-deficient female mice provide evidence that cohesins are a missing link in age-related nondisjunction.</a> Nat Genet. 37 (12), 1351-1355 (2005).</li><li>Freeman, S. B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+National+Down+Syndrome+Project:+design+and+implementation.">The National Down Syndrome Project: design and implementation.</a> Public Health Rep. 122 (1), 62-72 (2007).</li><li>Nagaoka, S. I., Hassold, T. J., Hunt, P. 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L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Defective+cohesin+is+associated+with+age-dependent+misaligned+chromosomes+in+oocytes.">Defective cohesin is associated with age-dependent misaligned chromosomes in oocytes.</a> Reprod Biomed Online. 16 (1), 103-112 (2008).</li><li>Subramanian, V. V., Bickel, S. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Aging+predisposes+oocytes+to+meiotic+nondisjunction+when+the+cohesin+subunit+SMC1+is+reduced.">Aging predisposes oocytes to meiotic nondisjunction when the cohesin subunit SMC1 is reduced.</a> PLoS Genet. 4 (11), e1000263 (2008).</li><li>Chiang, T., Duncan, F. E., Schindler, K., Schultz, R. M., Lampson, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evidence+that+weakened+centromere+cohesion+is+a+leading+cause+of+age-related+aneuploidy+in+oocytes.">Evidence that weakened centromere cohesion is a leading cause of age-related aneuploidy in oocytes.</a> Curr. Biol. 20 (17), 1522-1528 (2010).</li><li>Lister, L. M., 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=Age-related+meiotic+segregation+errors+in+mammalian+oocytes+are+preceded+by+depletion+of+cohesin+and+Sgo2.">Age-related meiotic segregation errors in mammalian oocytes are preceded by depletion of cohesin and Sgo2.</a> Curr. Biol. 20 (17), 1511-1521 (2010).</li><li>Duncan, F. E., 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=Chromosome+cohesion+decreases+in+human+eggs+with+advanced+maternal+age.">Chromosome cohesion decreases in human eggs with advanced maternal age.</a> Aging Cell. 11 (6), 1121-1124 (2012).</li><li>Yun, Y., Lane, S. I., Jones, K. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Premature+dyad+separation+in+meiosis+II+is+the+major+segregation+error+with+maternal+age+in+mouse+oocytes.">Premature dyad separation in meiosis II is the major segregation error with maternal age in mouse oocytes.</a> Development. 141 (1), 199-208 (2014).</li><li>Subramanian, V. V., Bickel, S. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Heterochromatin-mediated+association+of+achiasmate+homologues+declines+with+age+when+cohesion+is+compromised.">Heterochromatin-mediated association of achiasmate homologues declines with age when cohesion is compromised.</a> Genetics. 181, 1207-1218 (2009).</li><li>Jeffreys, C. A., Burrage, P. S., Bickel, S. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+model+system+for+increased+meiotic+nondisjunction+in+older+oocytes.">A model system for increased meiotic nondisjunction in older oocytes.</a> Curr. Biol. 13 (6), 498-503 (2003).</li><li>Weng, K. A., Jeffreys, C. A., Bickel, S. 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W., Hawley, R. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Direct+evidence+of+a+role+for+heterochromatin+in+meiotic+chromosome+segregation.">Direct evidence of a role for heterochromatin in meiotic chromosome segregation.</a> Cell. 86, 135-146 (1996).</li><li>Dernburg, A. F., Sedat, J. 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Los autores no declaran a intereses financieros en competencia.

El uso de peces las puntas de prueba para evaluar el estado de la cohesión de brazo en Prometafase y metafase I Drosophila ovocitos es un avance importante en el campo de la Drosophila meiosis. Históricamente, los investigadores de Drosophila se han limitado a pruebas genéticas para deducir la pérdida prematura de la cohesión de brazo en ovocitos maduros11,18,19. Ahora, con los métodos presentado...

Adecuada segregación de los cromosomas durante la mitosis y la meiosis requiere que hermana cohesión de cromátidas hermanas establecido, mantenido y liberado en una coordinada1,2. Cohesión se establece durante la fase S y es mediada por la cohesin complejo, que forma vínculos físicos que sostienen la hermana chromatids juntos. En la meiosis, cohesión distal a un crossover también funciona para unir homólogos recombinantes y esta asociación física ayuda a asegurar la orientación correcta del bivalente en la metafase del huso (figura 1)3,4, 5. Liberación del brazo de cohesión en el anaphase permite los homólogos segregar a los polos opuestos del huso. Sin embargo, si la cohesión del brazo es perdido prematuramente, recombinantes homólogos perderá su conexión física y segregan al azar, que puede dar lugar a gametos aneuploides (figura 1).
En ovocitos humanos, errores en la segregación cromosómica están la causa principal de abortos espontáneos y defectos de nacimiento, como síndrome de Down6, y su incidencia aumenta exponencialmente con la edad materna7. Cohesión de cromátidas se estableció en ovocitos fetales y la recombinación meiótica se completa antes del nacimiento. Ovocitos luego arrestar en mitad de la profase I hasta la ovulación y durante esta detención, la asociación física continua de homólogos recombinantes depende de la cohesión de cromátidas hermanas hermana. Por lo tanto, exacta segregación durante meiosis y los resultados del embarazo normal requiere que cohesión permanecen intactas hasta cinco décadas.
Pérdida prematura de cohesión durante el prolongado arresto meiótico de ovocitos humanos se ha propuesto contribuir al efecto de la edad materna y múltiples líneas de evidencia apoyan esta hipótesis8,9. Sin embargo, dado los desafíos de estudiar cohesión meiótico de ovocitos humanos, gran parte de nuestra comprensión de este fenómeno se basa en el uso del modelo organismos5,10,11,12, 1314,de,15.
Drosophila melanogaster ovocitos ofrecen numerosas ventajas para el estudio de la segregación meiótica de cohesión y cromosoma. Un simple análisis genético permite recuperar progenie de gametos aneuploides y medir la fidelidad de los X-la segregación cromosómica en una gran escala11,16,17. Por otra parte, uno puede determinar también si errores de segregación del cromosoma ocurren porque missegregate recombinantes homólogos durante la meiosis I, un fenotipo que es consistente con la prematura pérdida de brazo cohesión11,18, 19. observación del estado de cohesión meiótica de ovocitos de Drosophila también es posible usar en situ hibridación de la fluorescencia (pescado) directamente. Aunque fluorescentes oligonucleótidos que hibridan a secuencias repetitivas satélite han utilizado por más de una década para controlar pericentromeric cohesión en maduro Drosophila ovocitos4,20, análisis del brazo cohesión ha sido mucho más difícil. Visualización del estado de la cohesión del brazo requiere una sonda que abarca una extensa región de copia solo secuencias y es lo suficientemente brillante para dar lugar a señales visibles para cada hermana cromátides cuando existe cohesión de brazo. Además, las condiciones de fijación ovocitos y tamaño de los DNAs marcados deben facilitar penetración21 dentro del óvulo maduro grande de Drosophila (200 μm ancho por 500 μm de largo). Recientemente, un sondeo de brazo fue exitosamente utilizados visualizar Drosophila cromátides de ovocitos durante la anafase I, pero los autores indicó que no pudo detectar una señal en Prometafase o metafase detenido ovocitos22. Aquí proporcionamos un protocolo detallado para la generación de X-cromosoma brazo sondas de FISH y las condiciones de preparación de ovocitos que nos han permitido analizar por la prematura pérdida de hermana cohesión de cromátidas hermanas en Prometafase y metafase I ovocitos. Estas técnicas, que nos han permitido identificar productos génicos que se requieren para el mantenimiento de la cohesión meiótica, permitirá a otros análisis para hermana cohesión de cromátidas hermanas defectos en ovocitos maduros de Drosophila de diferentes genotipos.

<table><tbody><tr><td>&lt;strong&gt;Kits&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>Midi Prep kit</td><td>Qiagen</td><td>12143</td><td>Prep BAC clone DNA</td></tr><tr><td>GenomePlex Complete Whole Genome Amplification (WGA) Kit</td><td>Sigma</td><td>WGA2</td><td>Amplify BAC clone DNA</td></tr><tr><td>ARES Alexa Fluor 647 DNA labeling kit</td><td>Invitrogen</td><td>A21676</td><td>Label BAC clone DNA</td></tr><tr><td>PCR purification kit</td><td>Qiagen</td><td>28104</td><td>Remove non-conjugated dye following labeling of BAC clone DNA</td></tr><tr><td>&lt;strong&gt;Name&lt;/strong&gt;</td><td>&lt;strong&gt;Company&lt;/strong&gt;</td><td>&lt;strong&gt;Catalog Number&lt;/strong&gt;</td><td>&lt;strong&gt;Comments&lt;/strong&gt;</td></tr><tr><td>&lt;strong&gt;Chemicals &amp;amp; Solutions&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>&lt;strong&gt;Note: &lt;/strong&gt;All solutions are prepared using sterile ultrapure water and should be sterilized either by autoclave or filter sterilization.</td><td></td><td></td><td></td></tr><tr><td>Bovine serum albumin (BSA)</td><td>Fisher Scientific</td><td>BP1600-100</td><td>Prepare 10% stock&lt;br/&gt; Freeze aliquots</td></tr><tr><td>Calcium chloride</td><td>Fisher Scientific</td><td>C75-500</td><td></td></tr><tr><td>DAPI (4&amp;rsquo;, 6-Diamidino-2-Phenylindole, Dihydrochloride)</td><td>Invitrogen</td><td>D1306</td><td>&lt;strong&gt;Toxic:&lt;/strong&gt; wear appropriate protection. Prepare 100&amp;micro;g/ml stock in 100% ethanol, store in aliquots at -20 &amp;deg;C. Prepare 1 &amp;micro;g/ml solution in 2X SSCT before use.</td></tr><tr><td>Dextran sulfate</td><td>Sigma</td><td>D-8906</td><td></td></tr><tr><td>Drierite</td><td>Drierite Company</td><td>23001</td><td></td></tr><tr><td>Dithiothreitol (DTT)</td><td>Invitrogen</td><td>15508-013</td><td>Prepare 10 mM stock</td></tr><tr><td>dTTP (10 &amp;micro;mol, 100 &amp;micro;l)</td><td>Boehringer Mannheim</td><td>1277049</td><td>Prepare 1 mM stock</td></tr><tr><td>EDTA (Disodium ethylenediamine tetraacetic acid)</td><td>Fisher Scientific</td><td>S311-500</td><td>Prepare 250 mM stock</td></tr><tr><td>100% ethanol (molecular grade, 200 proof)</td><td>Decon Laboratories</td><td>2716</td><td></td></tr><tr><td>Tris (Ultra Pure)</td><td>Invitrogen</td><td>15504-020</td><td></td></tr><tr><td>EGTA (Ethylenebis(oxyethylenenitrilo)tetraacetic acid)</td><td>Sigma</td><td>E-3889</td><td></td></tr><tr><td>16% formaldehyde</td><td>Ted Pella, Inc.</td><td>18505</td><td>&lt;strong&gt;Toxic:&lt;/strong&gt; wear appropriate protection</td></tr><tr><td>Formamide</td><td>Invitrogen</td><td>AM9342</td><td>&lt;strong&gt;Toxic: &lt;/strong&gt;wear appropriate protection</td></tr><tr><td>Glucose</td><td>Fisher Scientific</td><td>D16-1</td><td></td></tr><tr><td>Glycogen</td><td>Roche</td><td>901393</td><td></td></tr><tr><td>HEPES</td><td>Boehringer Mannheim</td><td>737-151</td><td></td></tr><tr><td>Heptane</td><td>Fisher Scientific</td><td>H350-4</td><td>&lt;strong&gt;Toxic:&lt;/strong&gt; wear appropriate protection.</td></tr><tr><td>Hydrochloric acid</td><td>Millipore</td><td>HX0603-4</td><td>&lt;strong&gt;Toxic:&lt;/strong&gt; wear appropriate protection.</td></tr><tr><td>Hydroxylamine</td><td>Sigma</td><td>438227</td><td>Prepare 3 M stock</td></tr><tr><td>4.9 M Magnesium chloride</td><td>Sigma</td><td>104-20</td><td></td></tr><tr><td>Na&lt;sub&gt;2&lt;/sub&gt;HPO&lt;sub&gt;4 &lt;/sub&gt;&amp;Yuml; 7H&lt;sub&gt;2&lt;/sub&gt;O</td><td>Fisher Scientific</td><td>S373-500</td><td></td></tr><tr><td>NaH&lt;sub&gt;2&lt;/sub&gt;PO&lt;sub&gt;4 &lt;/sub&gt;&amp;Yuml; 2H&lt;sub&gt;2&lt;/sub&gt;O</td><td>Fisher Scientific</td><td>S369-500</td><td></td></tr><tr><td>Poly-L-lysine (0.1mg/ml)</td><td>Sigma</td><td>P8920-100</td><td></td></tr><tr><td>Potassium acetate</td><td>Fisher Scientific</td><td>BP364-500</td><td></td></tr><tr><td>Sodium acetate</td><td>Fisher Scientific</td><td>S209-500</td><td>Prepare 3M stock</td></tr><tr><td>Sodium cacodylate</td><td>Polysciences, Inc.</td><td>1131</td><td>&lt;strong&gt;Toxic: &lt;/strong&gt;wear appropriate protection. Prepare 400mM stock</td></tr><tr><td>Sodium citrate</td><td>Fisher Scientific</td><td>BP327-1</td><td></td></tr><tr><td>Sodium chloride</td><td>Fisher Scientific</td><td>S271-3</td><td>Sodium chloride</td></tr><tr><td>Sucrose</td><td>Fisher Scientific</td><td>S5-500</td><td></td></tr><tr><td>10% Tween 20</td><td>Thermo Scientific</td><td>28320</td><td>Surfact-Amps</td></tr><tr><td>10% Triton X-100</td><td>Thermo Scientific</td><td>28314</td><td>Surfact-Amps</td></tr><tr><td>&lt;strong&gt;Name&lt;/strong&gt;</td><td>&lt;strong&gt;Company&lt;/strong&gt;</td><td>&lt;strong&gt;Catalog Number&lt;/strong&gt;</td><td>&lt;strong&gt;Comments&lt;/strong&gt;</td></tr><tr><td>&lt;strong&gt;Solutions&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>&lt;strong&gt;Note: &lt;/strong&gt;All solutions are prepared using sterile ultrapure water and should be sterilized either by autoclave or filter sterilization.</td><td></td><td></td><td></td></tr><tr><td>TE buffer</td><td></td><td></td><td>10 mM Tris, 1 mM EDTA, pH = 8.0</td></tr><tr><td>20X SSC (Saline Sodium Citrate)</td><td></td><td></td><td>3 M NaCl, 300 mM sodium citrate</td></tr><tr><td>2X cacodylate fix solution</td><td></td><td></td><td>&lt;strong&gt;Toxic:&lt;/strong&gt; wear appropriate protection. 200 mM sodium cacodylate, 200 mM sucrose, 80 mM sodium acetate, 20 mM EGTA</td></tr><tr><td>1.1X Hybridization buffer</td><td></td><td></td><td>3.3X SSC, 55% formamide, 11% dextran sulfate</td></tr><tr><td>Fix solution</td><td></td><td></td><td>&lt;strong&gt;Toxic: &lt;/strong&gt;wear appropriate protection. 4% formaldehyde, 1X cacodylate fix solution</td></tr><tr><td>PBSBTx</td><td></td><td></td><td>1X PBS, 0.5% BSA, 0.1% Trition X-100</td></tr><tr><td>PBSTx</td><td></td><td></td><td>1X PBS, 1% Trition X-100</td></tr><tr><td>Extraction buffer (PBSTx + Rnase)</td><td></td><td></td><td>1X PBS, 1% Trition X-100, 100 &amp;micro;g/mL RNase</td></tr><tr><td>2X SSCT</td><td></td><td></td><td>2X SSC, 0.1% Tween 20</td></tr><tr><td>2X SSCT + 20% formamide</td><td></td><td></td><td>&lt;strong&gt;Toxic:&lt;/strong&gt; wear appropriate protection. 2X SSC, 0.1% Tween 20, 20% formamide</td></tr><tr><td>2X SSCT + 40% formamide</td><td></td><td></td><td>&lt;strong&gt;Toxic:&lt;/strong&gt; wear appropriate protection. 2X SSC, 0.1% Tween 20, 40% formamide</td></tr><tr><td>2X SSCT + 50% formamide</td><td></td><td></td><td>&lt;strong&gt;Toxic:&lt;/strong&gt; wear appropriate protection. 2X SSC, 0.1% Tween 20, 50% formamide</td></tr><tr><td>&lt;strong&gt;Name&lt;/strong&gt;</td><td>&lt;strong&gt;Company&lt;/strong&gt;</td><td>&lt;strong&gt;Catalog Number&lt;/strong&gt;</td><td>&lt;strong&gt;Comments&lt;/strong&gt;</td></tr><tr><td>&lt;strong&gt;Enzymes&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>AluI</td><td>New England Biolabs</td><td>R0137S</td><td></td></tr><tr><td>HaeIII</td><td>New England Biolabs</td><td>R0108S</td><td></td></tr><tr><td>MseI</td><td>New England Biolabs</td><td>R0525S</td><td></td></tr><tr><td>MspI</td><td>New England Biolabs</td><td>R0106S</td><td></td></tr><tr><td>RsaI</td><td>New England Biolabs</td><td>R0167S</td><td></td></tr><tr><td>BfuCI</td><td>New England Biolabs</td><td>R0636S</td><td></td></tr><tr><td>100X BSA</td><td>New England Biolabs</td><td></td><td>Comes with NEB enzymes</td></tr><tr><td>10X NEB buffer #2</td><td>New England Biolabs</td><td></td><td>Restriction enzyme digestion buffer. 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using fluorescence in situ hybridization (fish) to monitor the state of arm cohesion in prometaphase and metaphase i drosophila oocytes

En los seres humanos, errores de la segregación del cromosoma en ovocitos son responsables de la mayoría de los abortos espontáneos y defectos de nacimiento. Por otra parte, como la edad de las mujeres, el riesgo de concebir que un feto aneuploide aumenta considerablemente y este fenómeno se conoce como el efecto de la edad materna. Un requisito para la segregación del cromosoma exacta durante las divisiones meióticas es mantenimiento de hermana cohesión de cromátidas hermanas durante el período de profase prolongada experimentan de ovocitos. Pruebas citológicas en los seres humanos y organismos modelo sugieren que la cohesión meiótica se deteriora durante el proceso de envejecimiento. Además, errores de segregación en ovocitos humanos son más frecuentes durante la meiosis I, consistente con la prematura pérdida de cohesión del brazo. El uso de organismos modelo es fundamental para desentrañar los mecanismos que subyacen a la pérdida depende de la edad de la cohesión. Drosophila melanogaster ofrece varias ventajas para el estudio de la regulación de la cohesión meiótica de ovocitos. Sin embargo, hasta hace poco, sólo las pruebas genéticas estaban disponibles para análisis por pérdida de cohesión de brazo en ovocitos de diferentes genotipos o bajo diferentes condiciones experimentales. Aquí, un protocolo detallado es siempre para usar fluorescencia en situ hibridación (FISH) para visualizar directamente defectos cohesión brazo en Prometafase y metafase arresté a ovocitos de Drosophila . Generando una sonda de pescado que cruza por hibridación en el brazo distal del cromosoma X y recolectando pilas Z confocales, un investigador puede visualizar el número de señales individuales de peces en tres dimensiones y determinar si la hermana chromatid brazos son separados. El procedimiento descrito permite cuantificar defectos de cohesión brazo de cientos de ovocitos de Drosophila . Como tal, este método proporciona una herramienta importante para la investigación de los mecanismos que contribuyen al mantenimiento de la cohesión, así como los factores que conducen a su desaparición durante el proceso de envejecimiento.

Figura 5 presenta las imágenes obtenidas con una sonda de brazo que cruza por hibridación a citológico región 6E-7B en el cromosoma X . Este resultado de la sonda en una señal que se localiza junto con la de DAPI, es fácilmente distinguible del fondo y se ha utilizado con éxito para cuantificar defectos de cohesión brazo en diferentes genotipos19. Cuantificación de los defectos de cohesión se restringió a Prometafas...

Watch this Scientific Journal Video about Using Fluorescence In Situ Hybridization FISH to Monitor the State of Arm Cohesion in Prometaphase and Metaphase I Drosophila Oocytes at JoVE.com

Uso de FISH de hibridación in situ con fluorescencia para controlar el estado de cohesión del brazo en ovocitos de Drosophila prometafase y metafase I | Desarrollo | Biología | Video

Using Fluorescence In Situ Hybridization FISH to Monitor the State of Arm Cohesion in Prometaphase and Metaphase I Drosophila Oocytes

Con fluorescencia In Situ hibridación (pescado) para supervisar el estado de la cohesión de brazo en Prometafase y metafase I ovocitos de Drosophila

Este manuscrito presenta un detallado método para la generación X-cromosoma brazo sondas y rendimiento en situ hibridación de la fluorescencia (pescado) para examinar el estado de la hermana cohesión de cromátidas hermanas en Prometafase y metafase detenido Drosophila ovocitos. Este protocolo es adecuado para determinar si cohesión brazo meiótica es intacta o interrumpida en diferentes genotipos.

In humans, chromosome segregation errors in oocytes are responsible for the majority of miscarriages and birth defects. Moreover, as women age, their risk ...

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Using Fluorescence In Situ Hybridization (FISH) to Monitor the State of Arm Cohesion in Prometaphase and Metaphase I Drosophila Oocytes

Meiosis

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11.3K vistas.  Dartmouth College. Este manuscrito presenta un detallado método para la generación X-cromosoma brazo sondas y rendimiento en situ hibridación de la fluorescencia (pescado) para examinar el estado de la hermana cohesión de cromátidas hermanas en Prometafase y metafase detenido Drosophila ovocitos. Este protocolo es adecuado para determinar si cohesión brazo meiótica es intacta o interrumpida en diferentes genotipos.

Video: Using Fluorescence In Situ Hybridization FISH to Monitor the State of Arm Cohesion in Prometaphase and Metaphase I Drosophila Oocytes

High Resolution Fluorescent In Situ Hybridization in Drosophila Embryos and Tissues Using Tyramide Signal Amplification

In our efforts to determine the patterns of expression and subcellular localization of Drosophila RNAs on a genome-wide basis, and in a variety of tissues, we have developed numerous modifications and improvements to our original fluorescent in situ hybridization (FISH) protocol. To facilitate throughput and cost effectiveness, all steps, from probe generation to signal detection, are performed using exon 96-well microtiter plates. Digoxygenin (DIG)-labelled antisense RNA probes are produced using either cDNA clones or genomic DNA as templates. After tissue fixation and permeabilization, probes are hybridized to transcripts of interest and then detected using a succession of anti-DIG antibody conjugated to biotin, streptavidin conjugated to horseradish peroxidase (HRP) and fluorescently conjugated tyramide, which in the presence of HRP, produces a highly reactive intermediate that binds to electron dense regions of immediately adjacent proteins. These amplification and localization steps produce a robust and highly localized signal that facilitates both cellular and subcellular transcript localization. The protocols provided have been optimized to produce highly specific signals in a variety of tissues and developmental stages. References are also provided for additional variations that allow the simultaneous detection of multiple transcripts, or transcripts and proteins, at the same time.

High Resolution Fluorescent In Situ Hybridization in Drosophila Embryos and Tissues Using Tyramide Signal Amplification

The described RNA in situ hybridization protocol allows the detection of RNA in whole Drosophila embryos or dissected tissues. Using 96-well microtiter plates and tyramide signal amplification, transcripts can be detected at high resolution, sensitivity, and throughput, and at a relatively low cost.

Alta resolución fluorescente In Situ hibridación en embriones de Drosophila y tejidos utilizando amplificación de la señal de Tyramide

In our efforts to determine the patterns of expression and subcellular localization of Drosophila RNAs on a genome-wide basis, and in a variety of ...

Investigación

Genética

Using Mouse Oocytes to Assess Human Gene Function During Meiosis I

Embryonic aneuploidy is the major genetic cause of infertility in humans. Most of these events originate during female meiosis, and albeit positively correlated with maternal age, age alone is not always predictive of the risk of generating an aneuploid embryo. Therefore, gene variants might account for incorrect chromosome segregation during oogenesis. Given that access to human oocytes is limited for research purposes, a series of assays were developed to study human gene function during meiosis I using mouse oocytes. First, messenger RNA (mRNA) of the gene and gene variant of interest are microinjected into prophase I-arrested mouse oocytes. After allowing time for expression, oocytes are synchronously released into meiotic maturation to complete meiosis I. By tagging the mRNA with a sequence of a fluorescent reporter, such as green fluorescent protein (Gfp), the localization of the human protein can be assessed in addition to the phenotypic alterations. For example, gain or loss of function can be investigated by establishing experimental conditions that challenge the gene product to fix meiotic errors. Although this system is advantageous in investigating human protein function during oogenesis, adequate interpretation of results should be undertaken given that protein expression is not at endogenous levels and, unless controlled for (i.e. knocked out or down), murine homologs are also present in the system.

As the genetic variants associated with human disease begin to become uncovered, it is becoming increasingly important to develop systems with which to rapidly evaluate the biological significance of those identified variants. This protocol describes methods for evaluating human gene function during female meiosis I using mouse oocytes.

Uso de ovocitos de ratón para evaluar la función humana del Gene durante la Meiosis I

Embryonic aneuploidy is the major genetic cause of infertility in humans. Most of these events originate during female meiosis, and albeit positively ...

Use of Single Molecule Fluorescent In Situ Hybridization (SM-FISH) to Quantify and Localize mRNAs in Murine Oocytes

Current methods routinely used to quantify mRNA in oocytes and embryos include digital reverse-transcription polymerase chain reaction (dPCR), quantitative, real-time RT-PCR (RT-qPCR) and RNA sequencing. When these techniques are performed using a single oocyte or embryo, low-copy mRNAs are not reliably detected. To overcome this problem, oocytes or embryos can be pooled together for analysis; however, this often leads to high variability amongst samples. In this protocol, we describe the use of fluorescence in situ hybridization (FISH) using branched DNA chemistry. This technique identifies the spatial pattern of mRNAs in individual cells. When the technique is coupled with Spot Finding and Tracking&#160;computer software, the abundance of mRNAs in the cell can also be quantified. Using this technique, there is reduced variability within an experimental group and fewer oocytes and embryos are required to detect significant differences between experimental groups. Commercially available branched-DNA SM-FISH kits have been optimized to detect mRNAs in sectioned tissues or adherent cells on slides. However, oocytes do not effectively adhere to slides and some reagents in the kit were too harsh resulting in oocyte lysis. To prevent this lysis, several modifications were made to the FISH kit. Specifically, oocyte permeabilization and wash&#160;buffers designed for the immunofluorescence of oocytes and embryos replaced the proprietary buffers. The permeabilization, washes, and incubations with probes and amplifier were performed in 6-well plates and oocytes were placed on slides at the end of the protocol using mounting media. These modifications were able to overcome the limitations of the commercially available kit, in particular, the oocyte lysis. To accurately and reproducibly count the number of mRNAs in individual oocytes, computer software was used. Together, this protocol represents an alternative to PCR and sequencing to compare the expression of specific transcripts in single cells.

Use of Single Molecule Fluorescent In Situ Hybridization SM-FISH to Quantify and Localize mRNAs in Murine Oocytes

To reproducibly count the numbers of mRNAs in individual oocytes, single molecule RNA fluorescence in situ hybridization (RNA-FISH) was optimized for non-adherent cells. Oocytes were collected, hybridized with the transcript specific probes, and quantified using an image quantification software.

Uso de la sola molécula fluorescente en Situ del hibridación (SM-pescado) para cuantificar y Localize mRNAs en oocitos murinos

Current methods routinely used to quantify mRNA in oocytes and embryos include digital reverse-transcription polymerase chain reaction (dPCR), ...

Nuclear Migration in the Drosophila Oocyte

Live cell imaging is particularly necessary to understand the cellular and molecular mechanisms that regulate organelle movements, cytoskeleton rearrangements, or polarity patterning within the cells. When studying oocyte nucleus positioning, live-imaging techniques are essential to capture the dynamic events of this process. The Drosophila egg chamber is a multicellular structure and an excellent model system to study this phenomenon because of its large size and availability of numerous genetic tools. During Drosophila mid-oogenesis, the nucleus migrates from a central position within the oocyte to adopt an asymmetric position mediated by microtubule-generated forces. This migration and positioning of the nucleus are necessary to determine the polarity axes of the embryo and the subsequent adult fly. One characteristic of this migration is that it occurs in three dimensions (3D), creating a necessity for live imaging. Thus, to study the mechanisms that regulate nuclear migration, we have developed a protocol to culture the dissected egg chambers and perform live imaging for 12 h by time-lapse acquisitions using spinning-disk confocal microscopy. Overall, our conditions allow us to preserve Drosophila egg chambers alive for a long period of time, thereby enabling the completion of nuclear migration to be visualized in a large number of samples in 3D.

Nuclear Migration in the Drosophila Oocyte

In Drosophila, the oocyte nucleus undergoes microtubule-dependent migration during oogenesis. Here, we describe a protocol that was developed to follow the migration by performing live imaging on egg chambers ex-vivo. Our procedure maintains egg chambers alive for 12 h to acquire multi-position 3D time-lapse movies using spinning-disk confocal microscopy.

Migración nuclear en el ovocito Drosophila

Live cell imaging is particularly necessary to understand the cellular and molecular mechanisms that regulate organelle movements, cytoskeleton ...

Biología del Desarrollo

Studying Mitotic Checkpoint by Illustrating Dynamic Kinetochore Protein Behavior and Chromosome Motion in Living Drosophila Syncytial Embryos

The spindle assembly checkpoint (SAC) mechanism is an active signal, which monitors the interaction between chromosome kinetochores and spindle microtubules to prevent anaphase onset until the chromosomes are properly connected. Cells use this mechanism to prevent aneuploidy or genomic instability, and hence cancers and other human diseases like birth defects and Alzheimer's1. A number of the SAC components such as Mad1, Mad2, Bub1, BubR1, Bub3, Mps1, Zw10, Rod and Aurora B kinase have been identified and they are all kinetochore dynamic proteins2. Evidence suggests that the kinetochore is where the SAC signal is initiated. The SAC prime regulatory target is Cdc20. Cdc20 is one of the essential APC/C (Anaphase Promoting Complex or Cyclosome) activators3 and is also a kinetochore dynamic protein4-6. When activated, the SAC inhibits the activity of the APC/C to prevent the destruction of two key substrates, cyclin B and securin, thereby preventing the metaphase to anaphase transition7,8. Exactly how the SAC signal is initiated and assembled on the kinetochores and relayed onto the APC/C to inhibit its function still remains elusive.
Drosophila is an extremely tractable experimental system; a much simpler and better-understood organism compared to the human but one that shares fundamental processes in common. It is, perhaps, one of the best organisms to use for bio-imaging studies in living cells, especially for visualization of the mitotic events in space and time, as the early embryo goes through 13 rapid nuclear division cycles synchronously (8-10 minutes for each cycle at 25 &deg;C) and gradually organizes the nuclei in a single monolayer just underneath the cortex9.
Here, I present a bio-imaging method using transgenic Drosophila expressing GFP (Green Fluorescent Protein) or its variant-targeted proteins of interest and a Leica TCS SP2 confocal laser scanning microscope system to study the SAC function in flies, by showing images of GFP fusion proteins of some of the SAC components, Cdc20 and Mad2, as the example.

Studying Mitotic Checkpoint by Illustrating Dynamic Kinetochore Protein Behavior and Chromosome Motion in Living Drosophila Syncytial Embryos

The kinetochore is where the SAC initiates its signal monitoring the mitotic segregation of the sister chromatids. A method is described to visualize the recruitment and turnover of one of the kinetochore proteins and its coordination with the chromosome motion in Drosophila embryos using a Leica laser scanning confocal system.

El estudio de puesto de control mitótico, ilustrando comportamiento dinámico de proteínas cinetocoro y el movimiento de cromosomas en vivo<em&gt; Drosophila</em&gt; Los embriones Sincitial

The spindle assembly checkpoint (SAC) mechanism is an active signal, which monitors the interaction between chromosome kinetochores and spindle ...

Biología

Live Imaging of GFP-labeled Proteins in Drosophila Oocytes

The Drosophila oocyte has been established as a versatile system for investigating fundamental questions such as cytoskeletal function, cell organization, and organelle structure and function. The availability of various GFP-tagged proteins means that many cellular processes can be monitored in living cells over the course of minutes or hours, and using this technique, processes such as RNP transport, epithelial morphogenesis, and tissue remodeling have been described in great detail in Drosophila oocytes1,2.
The ability to perform video imaging combined with a rich repertoire of mutants allows an enormous variety of genes and processes to be examined in incredible detail. One such example is the process of ooplasmic streaming, which initiates at mid-oogenesis3,4. This vigorous movement of cytoplasmic vesicles is microtubule and kinesin-dependent5 and provides a useful system for investigating cytoskeleton function at these stages.
Here I present a protocol for time lapse imaging of living oocytes using virtually any confocal microscopy setup.

Live Imaging of GFP-labeled Proteins in Drosophila Oocytes

A protocol for live imaging of GFP-tagged proteins or autofluorescent structures in individual Drosophila oocytes is described.

Imágenes en directo de las proteínas GFP-etiquetados en<em&gt; Drosophila</em&gt; Los ovocitos

The  Drosophila oocyte has been established as a versatile system for investigating  fundamental questions such as cytoskeletal function, cell ...

Whole Mount RNA Fluorescent in situ Hybridization of Drosophila Embryos

Assessing the expression pattern of a gene, as well as the subcellular localization properties of its transcribed RNA, are key features for understanding its biological function during development. RNA in situ hybridization (RNA-ISH) is a powerful method used for visualizing RNA distribution properties, be it at the organismal, cellular or subcellular levels 1. RNA-ISH is based on the hybridization of a labeled nucleic acid probe (e.g. antisense RNA, oligonucleotides) complementary to the sequence of an mRNA or a non-coding RNA target of interest 2. As the procedure requires primary sequence information alone to generate sequence-specific probes, it can be universally applied to a broad range of organisms and tissue specimens 3. Indeed, a number of large-scale ISH studies have been implemented to document gene expression and RNA localization dynamics in various model organisms, which has led to the establishment of important community resources 4-11. While a variety of probe labeling and detection strategies have been developed over the years, the combined usage of fluorescently-labeled detection reagents and enzymatic signal amplification steps offer significant enhancements in the sensitivity and resolution of the procedure 12. Here, we describe an optimized fluorescent in situ hybridization method (FISH) employing tyramide signal amplification (TSA) to visualize RNA expression and localization dynamics in staged Drosophila embryos. The procedure is carried out in 96-well PCR plate format, which greatly facilitates the simultaneous processing of large numbers of samples.

Whole Mount RNA Fluorescent in situ Hybridization of Drosophila Embryos

Here we describe a whole-mount fluorescent in situ hybridization (FISH) protocol for determining the expression and localization properties of RNAs expressed during embryogenesis in the fruit fly, Drosophila melanogaster.

Todo el monte ARN fluorescente<em&gt; In situ</em&gt; La hibridación de<em&gt; Drosophila</em&gt; Los embriones

Assessing  the expression pattern of a gene, as well as the subcellular localization  properties of its transcribed RNA, are key features for ...

Techniques for Imaging Prometaphase and Metaphase of Meiosis I in Fixed Drosophila Oocytes

Chromosome segregation in human oocytes is error prone, resulting in aneuploidy, which is the leading genetic cause of miscarriage and birth defects. The study of chromosome behavior in oocytes from model organisms holds much promise to uncover the molecular basis of the susceptibility of human oocytes to aneuploidy. Drosophila melanogaster is amenable to genetic manipulation, with over 100 years of research, community, and technique development. Visualizing chromosome behavior and spindle assembly in Drosophila oocytes has particular challenges, however, due primarily to the presence of membranes surrounding the oocyte that are impenetrable to antibodies. We describe here protocols for the collection, preparation, and imaging of meiosis I spindle assembly and chromosome behavior in Drosophila oocytes, which allow the molecular dissection of chromosome segregation in this important model organism.

Techniques for Imaging Prometaphase and Metaphase of Meiosis I in Fixed Drosophila Oocytes

We present protocols for the collection, preparation, and imaging of mature Drosophila oocytes. These methods allow the visualization of chromosome behavior and spindle assembly and function during meiosis.

Técnicas de Imagen y Prometafase metafase de la meiosis I en fijo<em&gt; Drosophila</emLos ovocitos&gt;

Chromosome segregation in human oocytes is error prone, resulting in aneuploidy, which is the leading genetic cause of miscarriage and birth defects. The ...

Visualizing and Tracking Endogenous mRNAs in Live Drosophila melanogaster Egg Chambers

Fluorescence-based imaging techniques, in combination with developments in light microscopy, have revolutionized how cell biologists conduct live cell imaging studies. Methods for detecting RNAs have expanded greatly since seminal studies linked site-specific mRNA localization to gene expression regulation. Dynamic mRNA processes can now be visualized via approaches that detect mRNAs, coupled with microscopy set-ups that are fast enough to capture the dynamic range of molecular behavior. The molecular beacon technology is a hybridization-based approach capable of direct detection of endogenous transcripts in living cells. Molecular beacons are hairpin-shaped, internally quenched, single-nucleotide discriminating nucleic acid probes, which fluoresce only upon hybridization to a unique target sequence. When coupled with advanced fluorescence microscopy and high-resolution imaging, they enable one to perform spatial and temporal tracking of intracellular movement of mRNAs. Although this technology is the only method capable of detecting endogenous transcripts, cell biologists have not yet fully embraced this technology due to difficulties in designing such probes for live cell imaging. A new software application, PinMol, allows for enhanced and rapid design of probes best suited to efficiently hybridize to mRNA target regions within a living cell. In addition, high-resolution, real-time image acquisition and current, open source image analysis software allow for a refined data output, leading to a finer evaluation of the complexity underlying the dynamic processes involved in the mRNA&#39;s life cycle.
Here we present a comprehensive protocol for designing and delivering molecular beacons into Drosophila melanogaster egg chambers. Direct and highly specific detection and visualization of endogenous maternal mRNAs is performed via spinning disc confocal microscopy. Imaging data is processed and analyzed using object detection and tracking in Icy software to obtain details about the dynamic movement of mRNAs, which are transported and localized to specialized regions within the oocyte.

Visualizing and Tracking Endogenous mRNAs in Live Drosophila melanogaster Egg Chambers

Here, we present a protocol for the visualization, detection, analysis and tracking of endogenous mRNA trafficking in live Drosophila melanogaster egg chamber using molecular beacons, spinning disc confocal microscopy, and open-source analysis software.

Visualización y seguimiento de ARNm endógenos en cámaras de huevo Drosophila melanogaster en vivo

Fluorescence-based imaging techniques, in combination with developments in light microscopy, have revolutionized how cell biologists conduct live cell ...

Multiplex Detection of Gene Expression in the Intact Drosophila Brain Using Expansion-Assisted Iterative Fluorescence In Situ Hybridization

Understanding gene expression is essential for deciphering cellular functions. However, methods for analyzing the expression of numerous genes in situ within a given tissue remain limited. The EASI-FISH protocol described here has been adapted to detect the expression of dozens of genes in the intact adult Drosophila central nervous system (CNS) using commercially available reagents. This protocol includes a new gel formulation that enhances gel robustness, enabling multiple rounds of hybridization and allowing the embedding of multiple brains per gel. This improvement increases throughput, facilitates optimal comparison of experimental conditions, and reduces reagent costs. Additionally, by employing the GAL4-UAS system for co-detection of green fluorescent protein (GFP), gene expression can be visualized in specific neuronal or glial cell types. Notably, the high resolution achieved through expansion microscopy, combined with the sensitivity of the method, allows for the detection of single RNA transcripts. This approach effectively integrates high image quality with high throughput, making it a powerful tool for studying gene expression throughout the intact fly brain.

Expansion-Assisted Iterative Fluorescence In Situ Hybridization (EASI-FISH) is a robust technique that combines expansion microscopy with fluorescence in situ hybridization (FISH) to detect the expression of multiple genes in thick tissue. This protocol outlines recent advancements in the method and its adaptation for labeling the intact Drosophila central nervous system..

Understanding gene expression is essential for deciphering cellular functions. However, methods for analyzing the expression of numerous genes in situ ...

Con fluorescencia In Situ hibridación (pescado) para supervisar el estado de la cohesión de brazo en Prometafase y metafase I ovocitos de Drosophila

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Alta resolución fluorescente In Situ hibridación en embriones de Drosophila y tejidos utilizando amplificación de la señal de Tyramide

Uso de ovocitos de ratón para evaluar la función humana del Gene durante la Meiosis I

Uso de la sola molécula fluorescente en Situ del hibridación (SM-pescado) para cuantificar y Localize mRNAs en oocitos murinos

Migración nuclear en el ovocito Drosophila

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Todo el monte ARN fluorescente

Técnicas de Imagen y Prometafase metafase de la meiosis I en fijo

Visualización y seguimiento de ARNm endógenos en cámaras de huevo Drosophila melanogaster en vivo

Multiplex Detection of Gene Expression in the Intact Drosophila Brain Using Expansion-Assisted Iterative Fluorescence In Situ Hybridization