Name: efficient and rapid isolation of early-stage embryos from arabidopsis thaliana seeds
Uploaded: 2013-06-07T13:00:00
Description: Watch this Scientific Journal Video about Efficient and Rapid Isolation of Early-stage Embryos from Arabidopsis thaliana Seeds at JoVE.com

We would like to thank Tal Nawy and Martin Bayer for their advice on embryo isolation. MTR, VG, UG and CB devised the embryo isolation equipment. MTR, VG and CB developed the embryo isolation protocol. MTR, VG and CB established the protocol, isolated the embryos, and generated embryo cDNA, VG performed the PCR, MTR the GUS staining, JJ the FISH experiments. MTR, VG, CG and UG wrote the manuscript. This work was funded by the University of Z&uuml;rich, a Fellowship of the Roche Research Foundation (to MTR), and grants from the Swiss National Foundation (to UG and CB).

The procedure is summarized in the flowchart shown in Figure 1. The microcapillaries and the instrumental setup are shown in Figure 2 and Figure 3, and typical steps of embryo isolation are shown in Figure 4.
1. Material and Buffer Preparation
1.1 Silicon coating of glass microcapillaries
<ol>
 <li>Place the microcapillaries in a 15 ml Falcon tube with ~5 ml of Sigmacote (Sigma) and invert several ti...

<ol>
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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=Identification+of+a+DNA+methylation-independent+imprinting+control+region+at+the+Arabidopsis+MEDEA+locus.">Identification of a DNA methylation-independent imprinting control region at the Arabidopsis MEDEA locus.</a> Genes Dev. 26, 1837-1850 (2012).</li><li>Raissig, M. 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R., Schubert, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Interphase+chromosomes+in+Arabidopsis+are+organized+as+well+defined+chromocenters+from+which+euchromatin+loops+emanate.">Interphase chromosomes in Arabidopsis are organized as well defined chromocenters from which euchromatin loops emanate.</a> Proc. Natl. Acad. Sci. U.S.A. 99, 14584-14589 (2002).</li><li>Morris, J., Singh, J. M., Eberwine, J. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transcriptome+analysis+of+single+cells.">Transcriptome analysis of single cells.</a> J. Vis. Exp. (50), e2634 (2011).</li><li>Nodine, M. D., Bartel, D. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Maternal+and+paternal+genomes+contribute+equally+to+the+transcriptome+of+early+plant+embryos.">Maternal and paternal genomes contribute equally to the transcriptome of early plant embryos.</a> Nature. 482 (7383), (2012).</li><li>Jefferson, R. A., Kavanagh, T. A., Bevan, M. W. G. U. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=fusions:+beta-glucuronidase+as+a+sensitive+and+versatile+gene+fusion+marker+in+higher+plants.">fusions: beta-glucuronidase as a sensitive and versatile gene fusion marker in higher plants.</a> EMBO J. 6, 3901-3907 (1987).</li><li>Schmidt, A., W&#246;hrmann, H., Raissig, M. T., Arand, J., Gheyselinck, J., Gagliardini, V., Heichinger, C., Walter, J., Grossniklaus, U. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Polycomb+group+protein+MEDEA+and+the+DNA+methyltransferase+MET1+interact+in+Arabidopsis+to+repress+autonomous+endosperm+development.">The Polycomb group protein MEDEA and the DNA methyltransferase MET1 interact in Arabidopsis to repress autonomous endosperm development.</a> Plant J. 73 (5), (1111).</li></ol>

We developed an embryo isolation protocol that is rapid, effective, and can be easily transferred to other laboratories.
The equipment described here consists of an inverted microscope, a micromanipulator, glass microcapillaries, a vertical filament puller and a microinjector (Figure 3A). The setup is similar to the one described for single animal cell isolation for transcriptomics analyses 17. We also successfully worked with a more basic setup where glass microcap...

The embryo of flowering plants is surrounded by the endosperm, a nutritive tissue derived from a second fertilization event. Both embryo and endosperm are surrounded by several cell layers of the seed coat. Collectively these tissues form a seed, which develop inside the fruit. Thus, tissue- and cell-specific analyses of Arabidopsis embryos are strongly impaired due their inaccessibility. Nevertheless, embryos at the late-globular or later stages are relatively well amenable to manual dissection by using fine tungsten needles under the stereomicroscope, or by applying slight pressure on the seed using forceps to extract them. Such techniques were successfully used for transcriptome or epigenome profiling analyses such as microarray hybridization, bisulfite sequencing, or RNA sequencing (e.g. 1-3). In contrast, studies of embryos at the zygote to early globular stage remain technically challenging. To date, only a few studies have reported transcriptome analyses on young embryos using either laser-capture microdissection (LCM) of embryonic tissues from fixed seed sections 4 or manual extraction of individual embryos from within seeds using fine tools 5. However, LCM equipment is not commonly available and manual embryo extraction at early stages is time consuming and requiring excellent dissection skills that are not easily transferable. In addition to genome-wide analyses, in situ gene expression analyses are also difficult to perform on young, whole-mount embryos of Arabidopsis. To some extent, young embryos can be released on microscope slides by gentle pressure on the seeds and used for reporter gene assays or protein detection by immunostaining (for example see 6,7). This technique, however, does not allow high-throughput embryo isolation, thus hindering quantitative analyses.
Therefore, we developed an efficient and rapid protocol for early embryo isolation from Arabidopsis seeds that is simple to set up, easily transferable, and suitable for a variety of downstream applications. The basic principle is to gently crush seeds - dissected from young siliques in an Eppendorf tube using a plastic pestle in an appropriate isolation buffer. The seed extract is placed in droplets on a multi-well slide and is screened for the presence of released embryos at the desired stage using an inverted microscope. Embryos are collected using a glass microcapillary attached to a microinjector or a standard laboratory pipette. For molecular applications, embryos are washed twice by repeated release into drops of new isolation buffer before transferring them to the destination buffer in a minimal volume. For cytological applications (reporter assays, immunostaining, FISH), washing steps can be omitted.
The method offers several advantages: (i) it yields 25-40 embryos in ~45 min for cytological applications or in 3-4 hr for molecular applications (including the washing steps), (ii) it allows isolation of specific embryonic stages, (iii) it is easily transferable to other persons and laboratories due to its simple setup, (iv) it requires affordable equipment for the basic setup which is amenable to upgrades, and (v) it was successfully used for various downstream applications such as RNA sequencing 8, gene-specific DNA-methylation analysis 9, reporter assays (10 and Raissig et al., in prep.), and FISH (J. Jaenisch, U. Grossniklaus, C. Baroux unpublished, see Figure 5).

<table border="1">
	<tbody>
 <tr>
 <td>Name of the Reagent</td>
 <td>Company</td>
 <td>Catalogue Number</td>
 <td>Comments (optional)</td>
 </tr>
 <tr>
 <td></td>
 <td></td>
 <td></td>
 <td>REAGENTS</td>
 </tr>
 <tr>
 <td>Sigmacote</td>
 <td>SIGMA </td>
 <td>SL2-100 ml</td>
 <td></td>
 </tr>
 <tr>
 <td>RNAse OUT</td>
 <td>Invitrogen (life technologies)</td>
 <td>10777-019</td>
 <td></td>
 </tr>
 <tr>
 <td>First- strand buffer</td>
 <td>Invitrogen (life technologies)</td>
 <td>18064-022</td>
 <td>contained in Superscript II package</td>
 </tr>
 <tr>
 <td>DTT</td>
 <td>Invitrogen (life technologies)</td>
 <td>18064-022</td>
 <td>contained in Superscript II package</td>
 </tr>
 <tr>
 <td>Bovine serum albumin (BSA) 100x =10 mg/ml </td>
 <td>New England Biolabs Inc.</td>
 <td></td>
 <td>Different suppliers will also work </td>
 </tr>
 <tr>
 <td>Thin wall Capillaries 1.0 mm</td>
 <td>World Precision Instruments</td>
 <td>TW100F-4</td>
 <td></td>
 </tr>
 <tr>
 <td>DNA LoBind tube 0.5 ml</td>
 <td>Vaudaux-Eppendorf</td>
 <td>0030108.035</td>
 <td></td>
 </tr>
 <tr>
 <td>CellTrics&Delta; 30 &mu;m</td>
 <td>PARTEC</td>
 <td>04-0042-2316</td>
 <td></td>
 </tr>
 <tr>
 <td>5wells 10 mm diameter slides</td>
 <td>Electron Microscopy Sciences</td>
 <td>63421-10</td>
 <td></td>
 </tr>
 <tr>
 <td>Formaldehyde Solution</td>
 <td>Sigma-Aldrich</td>
 <td>F1635</td>
 <td></td>
 </tr>
 <tr>
 <td>Superfrost Plus slide</td>
 <td>Thermo Fisher</td>
 <td>J1800AMNZ</td>
 <td>Menzel-Gl&auml;ser</td>
 </tr>
 <tr>
 <td>Tris</td>
 <td>Amaresco</td>
 <td>0497</td>
 <td></td>
 </tr>
 <tr>
 <td>EDTA</td>
 <td>Applichem</td>
 <td>A2937</td>
 <td></td>
 </tr>
 <tr>
 <td>Glycin</td>
 <td>Fluka</td>
 <td>50050</td>
 <td></td>
 </tr>
 <tr>
 <td>SDS pellets</td>
 <td>Roth</td>
 <td>CN30.3</td>
 <td></td>
 </tr>
 <tr>
 <td>Micro Pestle</td>
 <td>VWR</td>
 <td>431-0094</td>
 <td></td>
 </tr>
 <tr>
 <td>Microfine insulin syringes</td>
 <td>BD</td>
 <td>U-100</td>
 <td></td>
 </tr>
 <tr>
 <td>DEPC</td>
 <td>Sigma-Aldrich</td>
 <td>D5758</td>
 <td></td>
 </tr>
 <tr>
 <td>Ethanol</td>
 <td>Schaurlau</td>
 <td>ET00102500</td>
 <td></td>
 </tr>
 <tr>
 <td>Forceps N5</td>
 <td>Dumont</td>
 <td>0108-5</td>
 <td></td>
 </tr>
 <tr>
 <td>Bioanalyzer Pico Chip</td>
 <td>Agilent Technologies</td>
 <td>5067-1513</td>
 <td></td>
 </tr>
 <tr>
 <td></td>
 <td></td>
 <td></td>
 <td>EQUIPMENT</td>
 </tr>
 <tr>
 <td>Inverted microscope</td>
 <td>Nikon TMS (Japan),</td>
 <td></td>
 <td></td>
 </tr>
 <tr>
 <td>Micromanipulator</td>
 <td>Leitz</td>
 <td></td>
 <td>Leica</td>
 </tr>
 <tr>
 <td>Micomanipulator Post mount LH1 probe</td>
 <td>Leica microsystems</td>
 <td>39430101</td>
 <td>Different brand will also do the work</td>
 </tr>
 <tr>
 <td>Vertical filament puller</td>
 <td>Sutter instrument</td>
 <td>P-20 model</td>
 <td>Other model are also suitable </td>
 </tr>
 <tr>
 <td>Cell Tram vario</td>
 <td>Vaudaux-Eppendorf</td>
 <td>5176.000.033</td>
 <td></td>
 </tr>
 <tr>
 <td>Bioanalyzer</td>
 <td>Agilent Technologies</td>
 <td>2100</td>
 <td></td>
 </tr>
 <tr>
 <td>Qubit Fluorometer</td>
 <td>Invitrogen (life technologies</td>
 <td></td>
 <td></td>
 </tr>
	 </tbody>
 </table>

efficient and rapid isolation of early-stage embryos from arabidopsis thaliana seeds

In flowering plants, the embryo develops within a nourishing tissue - the endosperm - surrounded by the maternal seed integuments (or seed coat). As a consequence, the isolation of plant embryos at early stages (1 cell to globular stage) is technically challenging due to their relative inaccessibility. Efficient manual dissection at early stages is strongly impaired by the small size of young Arabidopsis seeds and the adhesiveness of the embryo to the surrounding tissues. Here, we describe a method that allows the efficient isolation of young Arabidopsis embryos, yielding up to 40 embryos in 1 hr to 4 hr, depending on the downstream application. Embryos are released into isolation buffer by slightly crushing 250-750 seeds with a plastic pestle in an Eppendorf tube. A glass microcapillary attached to either a standard laboratory pipette (via a rubber tube) or a hydraulically controlled microinjector is used to collect embryos from droplets placed on a multi-well slide on an inverted light microscope. The technical skills required are simple and easily transferable, and the basic setup does not require costly equipment. Collected embryos are suitable for a variety of downstream applications such as RT-PCR, RNA sequencing, DNA methylation analyses, fluorescence in situ hybridization (FISH), immunostaining, and reporter gene assays.

Our embryo isolation procedure (Figure 1) allows isolation of up to 40 embryos in 4 hr if washes are performed, e.g. for molecular applications, or in less than an hour if washes are omitted, e.g. for cytological applications. Figure 2 displays high and low quality microcapillary tips and Figure 3 shows the setup of the embryo isolation machine. Figure 4 displays the process of embryo isolation on the inverted microscope.
<p class="...

Watch this Scientific Journal Video about Efficient and Rapid Isolation of Early-stage Embryos from Arabidopsis thaliana Seeds at JoVE.com

Efficient and Rapid Isolation of Early-stage Embryos from Arabidopsis thaliana Seeds

We report an efficient and simple method to isolate embryos at early stages of development from Arabidopsis thaliana seeds. Up to 40 embryos can be isolated in 1 hr to 4 hr, depending on the downstream application. The procedure is suitable for transcriptome, DNA methylation, reporter gene expression, immunostaining and fluorescence in situ hybridization analyses.

Efficient and Rapid Isolation of Early-stage Embryos from Arabidopsis thaliana Seeds

In flowering plants, the embryo develops within a nourishing tissue - the endosperm - surrounded by the maternal seed integuments (or seed coat). As a ...

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