Name: natural transformation, protein expression, and cryoconservation of the filamentous cyanobacterium phormidium lacuna
Uploaded: 2022-02-01T14:30:00
Description: Watch this Scientific Journal Video about Natural Transformation, Protein Expression, and Cryoconservation of the Filamentous Cyanobacterium Phormidium lacuna at JoVE.com

The work was supported by the Karlsruher Institute of Technology.

1. Isolation from the natural environment
NOTE: Green algae, diatoms, filamentous cyanobacteria, and other microalgae can be isolated. The protocol can be used for any microalga species from rockpools growing under laboratory conditions. Filamentous cyanobacteria that belong to Oscillatoriales can be easily recognized by their movement and filamentous shape. The species can be identified in a semipure state by genome sequencing or 16S rRNA sequencing.
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	<li>Transfer liqu...

<ol>
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A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optimized+electroporation-induced+transformation+in+Microcystis+aeruginosa+PCC7806.">Optimized electroporation-induced transformation in Microcystis aeruginosa PCC7806.</a> Biotechnologie Agronomie Societe et Environnement. 14 (1), 149-152 (2010).</li><li>Nies, F., Mielke, M., Pochert, J., Lamparter, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Natural+transformation+of+the+filamentous+cyanobacterium+Phormidium+lacuna.">Natural transformation of the filamentous cyanobacterium Phormidium lacuna.</a> PLoS One. 15 (6), 0234440 (2020).</li><li>Sode, K., Tatara, M., Takeyama, H., Burgess, J. 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R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Light+regulation+of+type+IV+pilus-dependent+motility+by+chemosensor-like+elements+in+Synechocystis+PCC6803.">Light regulation of type IV pilus-dependent motility by chemosensor-like elements in Synechocystis PCC6803.</a> Proceedings of the National Academy of Sciences of the United States of America. 98 (13), 7540-7545 (2001).</li><li>Guillard, R. R., Ryther, 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=Studies+of+marine+planktonic+diatoms.+I.+Cyclotella+nana+Hustedt,+and+Detonula+confervacea+(cleve)+Gran.">Studies of marine planktonic diatoms. I. Cyclotella nana Hustedt, and Detonula confervacea (cleve) Gran.</a> Canadian Journal of Microbiology. 8, 229-239 (1962).</li><li>Kester, D. R., Duedall, I. W., Connors, D. N., Pytkowicz, R. 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P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+improved+method+for+genomic+DNA+extraction+from+cyanobacteria.">An improved method for genomic DNA extraction from cyanobacteria.</a> World Journal of Microbiology &amp; Biotechnology. 27, 1225-1230 (2011).</li><li>French, C. S., Milner, H. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Disintegration+of+bacteria+and+small+particles+by+high-pressure+extrusion.">Disintegration of bacteria and small particles by high-pressure extrusion.</a> Methods in Enzymology. 1, 64-67 (1955).</li><li>Sambrook, J., Fritsch, E. F., Maniatis, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Molecular cloning, a laboratory manual. 2nd ed. , (1989).</li><li>Lamparter, T., 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+involvement+of+type+IV+pili+and+phytochrome+in+gliding+motility,+lateral+motility+and+phototaxis+of+the+cyanobacterium+Phormidium+lacuna.">The involvement of type IV pili and phytochrome in gliding motility, lateral motility and phototaxis of the cyanobacterium Phormidium lacuna.</a> bioRxiv. , (2021).</li><li>Nies, F., 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=Characterization+of+Phormidium+lacuna+strains+from+the+North+Sea+and+the+Mediterranean+Sea+for+biotechnological+applications.">Characterization of Phormidium lacuna strains from the North Sea and the Mediterranean Sea for biotechnological applications.</a> Process Biochemistry. 59, 194-206 (2017).</li><li>Kachel, B., Mack, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Engineering+of+Synechococcus+sp.+strain+PCC+7002+for+the+photoautotrophic+production+of+light-sensitive+riboflavin+(vitamin+B2).">Engineering of Synechococcus sp. strain PCC 7002 for the photoautotrophic production of light-sensitive riboflavin (vitamin B2).</a> Metabolic Engineering. 62, 275-286 (2020).</li><li>Lukavsky, J., Cepak, V., Komarek, J., Kasparkova, M., Takacova, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Catalogue+of+algal+and+cyanobacterial+strains+of+culture+collection+of+autotrophic+organisms+at+Trebon.">Catalogue of algal and cyanobacterial strains of culture collection of autotrophic organisms at Trebon.</a> Algological Studies. 63, 59-112 (1992).</li><li>Philbrick, J. B., Diner, B. A., Zilinskas, B. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Construction+and+characterization+of+cyanobacterial+mutants+lacking+the+manganese-stabilizing+polypeptide+of+photosystem-ii.">Construction and characterization of cyanobacterial mutants lacking the manganese-stabilizing polypeptide of photosystem-ii.</a> Journal of Biological Chemistry. 266 (20), 13370-13376 (1991).</li><li>Pinevich, A. V., Veprritskii, A. A., Gromov, B. V., Krautvald, K., Titova, N. 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G., Friedl, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Additions+to+the+culture+collection+of+algae+at+Gottingen+since+1997.">Additions to the culture collection of algae at Gottingen since 1997.</a> Nova Hedwigia. 71 (1-2), 243-262 (2000).</li><li>Takano, H., Arai, T., Hirano, M., Matsunaga, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+intensity+and+quality+of+light+on+phycocyanin+production+by+a+marine+cyanobacterium+Synechococcus+sp.+042902.">Effects of intensity and quality of light on phycocyanin production by a marine cyanobacterium Synechococcus sp. 042902.</a> Applied Microbiology and Biotechnology. 43 (6), 1014-1018 (1995).</li><li>Carrer, H., Hockenberry, T. 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Although many strains of cyanobacteria are available from culture collections32,33,34,35,36, there is still a demand for new cyanobacteria from the wild because these species are adapted to specific properties. P. lacuna was collected from rockpools and is adapted to variations of salt concentrations and temperature30. Strains ...

Cyanobacteria are prokaryotic organisms that utilize photosynthesis as an energy source1,2. Research is increasingly focused on cyanobacterial species. Several cyanobacteria can be transformed with DNA3. Genes can be knocked out or overexpressed in these species. However, transformation is restricted to a few species4,5,6,7,8,9,10,11, and it can be difficult to establish transformation in strains from culture collections or the wild8. Strains of the filamentous species Phormidium lacuna (Figure 1) were isolated from marine rockpools, in which environmental conditions, such as salt concentrations or temperature, fluctuate over time. These filamentous cyanobacteria can be used as model organisms for the order Oscillatoriales12 to which they belong.
During trials testing gene transfer by electroporation13,14&#160;it was found that P. lacuna can be transformed by natural transformation15. In this process, DNA is taken up naturally by some cells. Compared to other methods of transformation16,17, natural transformation has the advantage of not requiring additional tools that could complicate the procedure. For example, electroporation requires proper cuvettes, intact wires, and selection of the proper voltage. P. lacuna is presently the only Oscillatoriales member susceptible to natural transformation. Because the original protocol is based on electroporation protocols, it still included several washing steps that might be unnecessary. Different approaches were tested to simplify the protocol, leading to the transformation protocol presented here.
The genome sequence is essential for further molecular studies based on gene knockout or overexpression. Although genome sequences can be obtained with next-generation sequencing machines within short periods, the extraction of DNA can be difficult and depends on the species. With P. lacuna, several protocols were tested. A modified cetyl trimethyl ammonium bromide (CTAB)-based method was then established, resulting in acceptable purity of DNA and DNA yields of each purification cycle for continued work in the laboratory. The genome of five strains could be sequenced with this protocol. The next logical transformation step was to establish protein expression in P. lacuna.
The sfGFP used as a marker protein in this protocol can be detected with any fluorescence microscope. All promoters that were tested could be used for P. lacuna sfGFP expression. The increasing number of strains arising from transformation has resulted in the need for a method for storing the cultures. Such methods are established for Escherichia coli and many other bacteria18. In standard protocols, glycerol cultures are prepared, transferred in liquid nitrogen, and stored at -80 &#176;C. This method requires only a few steps and is highly reliable for those species for which it is established. The standard protocol was not feasible for P. lacuna because living cells could not be recovered in all cases. However, when glycerol was removed after thawing, cells of all trials survived. Simple methods are presented for the analysis of motility of P. lacuna, which can be combined with knockout mutagenesis to investigate type IV pili or the role of photoreceptors. These assays are different from those of single-celled cyanobacteria19,20,21 and can also be useful for other Oscillatoria.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Autoclave 3870 ELV</td>
			<td>Tuttnauer</td>
			<td>3870 ELV</td>
			<td></td>
		</tr>
		<tr>
			<td>Bacto Agar</td>
			<td>OttoNorwald</td>
			<td>214010</td>
			<td></td>
		</tr>
		<tr>
			<td>BG-11 Freshwater Solution</td>
			<td>Sigma Aldrich</td>
			<td>C3061</td>
			<td></td>
		</tr>
		<tr>
			<td>BG-11 medium</td>
			<td>Merck</td>
			<td>73816-250ML</td>
			<td></td>
		</tr>
		<tr>
			<td>Boric acid</td>
			<td>Merck</td>
			<td>10043-35-3</td>
			<td>H3BO3</td>
		</tr>
		<tr>
			<td>Calcium chloride dihydrate</td>
			<td>Carl Roth</td>
			<td>10035-04-8</td>
			<td>CaCl2 &#183; 2 H2O</td>
		</tr>
		<tr>
			<td>Cell culture flasks Cellstar with filter screw cap, sterile, 250 mL</td>
			<td>Greiner</td>
			<td>658190</td>
			<td></td>
		</tr>
		<tr>
			<td>Cell culture flasks Cellstar with filter screw cap, sterile, 50 mL</td>
			<td>Greiner</td>
			<td>601975</td>
			<td></td>
		</tr>
		<tr>
			<td>Centrifuge LYNX 4000</td>
			<td>Thermo Scientific</td>
			<td>75006580</td>
			<td>and rotor</td>
		</tr>
		<tr>
			<td>Centrifuge microstar 17</td>
			<td>VWR International</td>
			<td>N/A</td>
			<td>for up to 13,000 rpm</td>
		</tr>
		<tr>
			<td>Cetyltrimethylammonium Bromide (CTAB)</td>
			<td>PanReac AppliChem</td>
			<td>57-09-0</td>
			<td>C19H42BrN</td>
		</tr>
		<tr>
			<td>Chloroform : Isoamyl Alcohol 24 : 1</td>
			<td>PanReac AppliChem</td>
			<td> 
			A1935</td>
			<td></td>
		</tr>
		<tr>
			<td>Cobalt(II) chloride hexahydrate</td>
			<td>Merck</td>
			<td>7791-13-1</td>
			<td>CoCl2 &#183; 6 H2O</td>
		</tr>
		<tr>
			<td>Copper(II) sulphate pentahydrate</td>
			<td>Merck</td>
			<td>7758-99-8</td>
			<td>&#160;CuSO4 &#183; 5 H2O</td>
		</tr>
		<tr>
			<td>D(+)-Biotin</td>
			<td>Carl Roth</td>
			<td>58-85-5</td>
			<td>&#160;C10H16N2O3S</td>
		</tr>
		<tr>
			<td>DNA ladder 1 kb</td>
			<td>New England Biolabs</td>
			<td>N3232</td>
			<td></td>
		</tr>
		<tr>
			<td>DNA ladder 100 bp</td>
			<td>New England Biolabs</td>
			<td>N3231</td>
			<td></td>
		</tr>
		<tr>
			<td>Electrical pipetting help accujet-pro S</td>
			<td>Brand GmbH</td>
			<td>26360</td>
			<td>for pipetting 1-25 mL</td>
		</tr>
		<tr>
			<td>Ethanol</td>
			<td>VWR</td>
			<td>64-17-5</td>
			<td>C2H6O</td>
		</tr>
		<tr>
			<td>Ethylenediamine tetraacetic acid disodium salt dihydrate</td>
			<td>Carl Roth</td>
			<td>6381-92-6</td>
			<td>EDTA-Na2 &#183; 2 H2O</td>
		</tr>
		<tr>
			<td>Fluorescence microscope ApoTome</td>
			<td>Zeiss</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Fluorescence microscope Axio Imager 2</td>
			<td>Zeiss</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>French Pressure Cell Press</td>
			<td>American Instrument Company</td>
			<td>N/A</td>
			<td></td>
		</tr>
		<tr>
			<td>Gel documation System Saffe Image</td>
			<td>Invitrogen</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Gelelctrophoresis system Mupid-One/-exu</td>
			<td>ADVANCED</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Glassware, different</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Glycerol</td>
			<td>Carl Roth</td>
			<td>56-81-5</td>
			<td>C3H8O3</td>
		</tr>
		<tr>
			<td>Iron(III) chloride hexahydrate</td>
			<td>Merck</td>
			<td>10025-77-1</td>
			<td>&#160;FeCl3 &#183; 6 H2O</td>
		</tr>
		<tr>
			<td>Kanamycin</td>
			<td>Sigma-Aldrich</td>
			<td>25389-94-0</td>
			<td></td>
		</tr>
		<tr>
			<td>Kanamycin sulphate</td>
			<td>Carl Roth</td>
			<td>25389-94-0</td>
			<td>C18H36N4O11 &#183; H2SO4</td>
		</tr>
		<tr>
			<td>Lauroylsarcosine, Sodium Salt (Sarcosyl)</td>
			<td>Sigma Aldrich</td>
			<td>137-16-6</td>
			<td>C15H28NO3 &#183; Na</td>
		</tr>
		<tr>
			<td>LB Broth (Lennox)</td>
			<td>Carl Roth</td>
			<td>X964.4</td>
			<td></td>
		</tr>
		<tr>
			<td>Light source, fluorescent tube L18W/954 daylight</td>
			<td>OSRAM</td>
			<td></td>
			<td>cultivation of cyanobacteria</td>
		</tr>
		<tr>
			<td>Light source, LED panel XL 6500K 140 W</td>
			<td>Bloom Star</td>
			<td>N/A</td>
			<td>cultivation of cyanobacteria, up to 1,000 &#181;mol m-2 s-1</td>
		</tr>
		<tr>
			<td>Magnesium chloride hexahydrate</td>
			<td>Carl Roth</td>
			<td>7791-18-6</td>
			<td>MgCl2 &#183; 6 H2O</td>
		</tr>
		<tr>
			<td>Manganese(II) chloride tetrahydrate</td>
			<td>Serva</td>
			<td>13446-34-9</td>
			<td>MnCl2 &#183; 4 H2O</td>
		</tr>
		<tr>
			<td>Microscope DM750</td>
			<td>Zeiss</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Midi prep plasmid extraction kit NucleoBond Xtra Midi kit</td>
			<td>Macherey-NAGEL GmbH &#38; Co. KG</td>
			<td>REF740410.50</td>
			<td></td>
		</tr>
		<tr>
			<td>Minicomputer Raspberry Pi 4 +</td>
			<td>Conrad Electronics</td>
			<td>2138863-YD</td>
			<td>for time-lapse recording</td>
		</tr>
		<tr>
			<td>Ocular camera EC3</td>
			<td>Leica</td>
			<td></td>
			<td>for continuous recording up to 30 s</td>
		</tr>
		<tr>
			<td>Ocular camera MikrOkular Full HD</td>
			<td>Bresser</td>
			<td></td>
			<td>for time-lapse recordings, coupled to Raspberry Pi minicomputer</td>
		</tr>
		<tr>
			<td>Petri dishes polystyrole, 100 mm x 20 mm</td>
			<td>Merck</td>
			<td>P5606-400EA</td>
			<td></td>
		</tr>
		<tr>
			<td>Petri dishes polystyrole, 60 mm x 15 mm</td>
			<td>Merck</td>
			<td>P5481-500EA</td>
			<td></td>
		</tr>
		<tr>
			<td>Photometer Nanodrop ND-1000</td>
			<td>Peqlab Biotechnologie</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Photometer Uvikon XS</td>
			<td>Goebel Instrumentelle Analytik GmbH</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Pipetman 100-1,000 &#181;L</td>
			<td>Gilson</td>
			<td>SKU: FA10006M</td>
			<td></td>
		</tr>
		<tr>
			<td>Pipetman 10-100 &#181;L</td>
			<td>Gilson</td>
			<td>SKU: FA10004M</td>
			<td></td>
		</tr>
		<tr>
			<td>Plastic pipettes 10 mL, sterile</td>
			<td>Greiner</td>
			<td>607107</td>
			<td></td>
		</tr>
		<tr>
			<td>Plastic tube, sterile, 15 mL</td>
			<td>Greiner</td>
			<td>188271</td>
			<td></td>
		</tr>
		<tr>
			<td>Plastic tube, sterile, 50 mL</td>
			<td>Greiner</td>
			<td>227261</td>
			<td></td>
		</tr>
		<tr>
			<td>Potassium bromide</td>
			<td>Carl Roth</td>
			<td>7758-02-3</td>
			<td>KBr</td>
		</tr>
		<tr>
			<td>Potassium chloride</td>
			<td>Carl Roth</td>
			<td>7447-40-7</td>
			<td>KCl</td>
		</tr>
		<tr>
			<td>Power supply Statron 3252-1</td>
			<td>Statron Ger&#228;tetechnik GmbH</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Power supply Voltcraft PPS 16005</td>
			<td>Conrad Electronics</td>
			<td></td>
			<td>for LED</td>
		</tr>
		<tr>
			<td>Proteinase K</td>
			<td>Promega</td>
			<td>MC500C</td>
			<td>from Maxwell 16 miRNA Tissue Kit AS1470</td>
		</tr>
		<tr>
			<td>Q5 polymerase</td>
			<td>New England Biolabs</td>
			<td>M0491S</td>
			<td></td>
		</tr>
		<tr>
			<td>Sequencing kit NextSeq 500/550 v2.5</td>
			<td>Illumina</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Sequencing system NextSeq 550 SY-415-1002</td>
			<td>Illumina</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Shaker Unimax 2010</td>
			<td>Heidolph Instruments</td>
			<td></td>
			<td>for cultivation</td>
		</tr>
		<tr>
			<td>Sodium acetate</td>
			<td>Carl Roth</td>
			<td>127-09-3</td>
			<td>NaCH3COO</td>
		</tr>
		<tr>
			<td>Sodium chloride</td>
			<td>Carl Roth</td>
			<td>7647-14-5</td>
			<td>NaCl</td>
		</tr>
		<tr>
			<td>Sodium dihydrogen phosphate monohydrate</td>
			<td>Carl Roth</td>
			<td>10049-21-5</td>
			<td>NaH2PO4 &#183; H2O</td>
		</tr>
		<tr>
			<td>Sodium fluoride</td>
			<td>Carl Roth</td>
			<td>7681-49-4</td>
			<td>NaF</td>
		</tr>
		<tr>
			<td>Sodium hydrogen carbonate</td>
			<td>Carl Roth</td>
			<td>144-55-8</td>
			<td>NaHCO3</td>
		</tr>
		<tr>
			<td>Sodium molybdate dihydrate</td>
			<td>Serva</td>
			<td>10102-40-6</td>
			<td>Na2MoO4 &#183; 2 H2O</td>
		</tr>
		<tr>
			<td>Sodium nitrate</td>
			<td>Merck</td>
			<td>7631-99-4</td>
			<td>NaNO3</td>
		</tr>
		<tr>
			<td>Sodium sulphate</td>
			<td>Carl Roth</td>
			<td>7757-82-6</td>
			<td>Na2SO4</td>
		</tr>
		<tr>
			<td>Strontium chloride hexahydrate</td>
			<td>Carl Roth</td>
			<td>10025-70-4</td>
			<td>SrCl2 &#183; 6 H2O</td>
		</tr>
		<tr>
			<td>Thiamine hydrochloride</td>
			<td>Merck</td>
			<td>67-03-8</td>
			<td>C12H17ClN4OS &#183; HCl</td>
		</tr>
		<tr>
			<td>TRIS</td>
			<td>Carl Roth</td>
			<td>77-86-1</td>
			<td>C4H11NO3</td>
		</tr>
		<tr>
			<td>Ultrasonic device UP100H with sonotrode MS3</td>
			<td>Hielscher Ultrasound Technology</td>
			<td>UP100H</td>
			<td></td>
		</tr>
		<tr>
			<td>Ultraturrax Silent Crusher M</td>
			<td>Heidolph Instruments</td>
			<td></td>
			<td>homogenizer</td>
		</tr>
		<tr>
			<td>Urea</td>
			<td>Carl Roth</td>
			<td>57-13-6</td>
			<td>CH4N2O</td>
		</tr>
		<tr>
			<td>Vitamin B12</td>
			<td>Sigma</td>
			<td>68-19-9</td>
			<td>C63H88CoN14O14P</td>
		</tr>
		<tr>
			<td>Vitamin solution</td>
			<td></td>
			<td></td>
			<td>0.3 &#181;M thiamin-HCl, 2.1 nM biotin, 0.37 nM cyanocobalamin</td>
		</tr>
		<tr>
			<td>Water Stills, Water treatment</td>
			<td>VEOLIA water technologies</td>
			<td>ELGA_21001</td>
			<td></td>
		</tr>
		<tr>
			<td>Zinc sulphate heptahydrate</td>
			<td>Sigma</td>
			<td>7446-20-0</td>
			<td>ZnSO4 &#183; 7 H2O</td>
		</tr>
		<tr>
			<td>software, URL</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>gatb-minia program for DNA assembly</td>
			<td>https://github.com/GATB/gatb-minia-pipeline</td>
			<td>makes large scaffolds from short DNA reads, Linux based</td>
			<td></td>
		</tr>
		<tr>
			<td>ImageJ</td>
			<td></td>
			<td>software for immage processing (pixel intensities, circle diameter)</td>
			<td></td>
		</tr>
		<tr>
			<td>RAST annotation server</td>
			<td>https://rast.nmpdr.org</td>
			<td>input: genome DNA sequence, detects open reading frames, lists protein sequences and their functions</td>
			<td></td>
		</tr>
		<tr>
			<td>Culture media</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Artificial seawater</td>
			<td colspan="3">0.41 M NaCl , 53 mM MgCl2,28 mM Na2SO4, 10 mM CaCl2 , 9 mM&#160; KCl , 2.4 mM NaHCO3 ,0.84 mM KBr, 0.49 mM H3BO3, 90 &#181;M SrCl2, 72 &#181;M NaF</td>
		</tr>
		<tr>
			<td>f/2 -liquid medium</td>
			<td colspan="3">artificial seawater, 0.1 % (v/v) trace element solution, 0.05 % (v/v) vitamin solution, 0.88 mM NaNO3, 36 &#181;M NaH2PO4&#160;</td>
		</tr>
		<tr>
			<td>f/2+ liquid medium</td>
			<td colspan="3">f/2-medium, with 10 times increased NaNO3 and NaH2PO4 (0.88 mM NaNO3, 36 &#181;M NaH2PO4</td>
		</tr>
		<tr>
			<td>f/2+-agar</td>
			<td colspan="3">3 % (w/v) bacto agar, artificial seawater, 0.1 % (v/v) trace element solution, 0.05 % (v/v) vitamin solution ,8.8 mM NaNO3, 0.36 mM NaH2PO4</td>
		</tr>
		<tr>
			<td>f/2-agar</td>
			<td colspan="3">3 % (w/v) bacto agar, artificial seawater, 0.1 % (v/v) trace element solution, 0.05 % (v/v) vitamin solution ,0.88 mM NaNO3, 36 &#181;M NaH2PO4</td>
		</tr>
		<tr>
			<td>Trace element solution</td>
			<td colspan="3">0.36 mM NaH2PO4, 12 &#181;M Na2EDTA, 39 nM CuSO4, 26 nM Na2MoO4 , 77 nM ZnSO4, 42 nM CoCl2, 0.91 &#181;M MnCl2</td>
		</tr>
		<tr>
			<td>Vitamin solution</td>
			<td colspan="2">0.3 &#181;M thiamin-HCl, 2.1 nM biotin, 0.37 nM cyanocobalamin</td>
			<td></td>
		</tr>
	</tbody>
</table>

natural transformation, protein expression, and cryoconservation of the filamentous cyanobacterium phormidium lacuna

Cyanobacteria are the focus of basic research and biotechnological projects in which solar energy is utilized for biomass production. Phormidium lacuna is a newly isolated filamentous cyanobacterium. This paper describes how new filamentous cyanobacteria can be isolated from marine rockpools. It also describes how DNA can be extracted from filaments and how the genomes can be sequenced. Although transformation is established for many single-celled species, it is less frequently reported for filamentous cyanobacteria. A simplified method for the natural transformation of P. lacuna is described here. P. lacuna is the only member of the order Oscillatoriales for which natural transformation is established. This paper also shows how natural transformation is used to express superfolder green fluorescent protein (sfGFP). An endogenous cpcB promoter induced approximately 5 times stronger expression than cpc560, A2813, or psbA2 promoters from Synechocystis sp. PCC6803. Further, a method for the cryopreservation of P. lacuna and Synechocystis sp. CPP 6803 was established, and methods for assessing motility in a liquid medium and on agar and plastic surfaces are described.

Following the above-mentioned methods, 5 different strains of P. lacuna were isolated from rockpools and sequenced (Figure 1 and Table 1). All cultures were sterile after ~1 year of subculturing except P. lacuna HE10JO. This strain is still contaminated with Marivirga atlantica, a marine bacterium. During subsequent Helgoland excursions, other filamentous cyanobacteria were isolated from rock pools, which are different from P. lacuna and n...

Watch this Scientific Journal Video about Natural Transformation, Protein Expression, and Cryoconservation of the Filamentous Cyanobacterium Phormidium lacuna at JoVE.com

Natural Transformation, Protein Expression, and Cryoconservation of the Filamentous Cyanobacterium Phormidium lacuna

Phormidium lacuna is a filamentous cyanobacterium that was isolated from marine rockpools. This article describes the isolation of filaments from natural sources, DNA extraction, genome sequencing, natural transformation, expression of sfGFP, cryoconservation, and motility methods.

Natural Transformation, Protein Expression, and Cryoconservation of the Filamentous Cyanobacterium Phormidium lacuna

Cyanobacteria are the focus of basic research and biotechnological projects in which solar energy is utilized for biomass production. Phormidium lacuna is ...

This protocol describes how filamentous cyanobacterium that belongs to oscillatoriales can be transformed by natural transformation. It also shows how different kinds of motion can be studied. Natural transformation is the simplest transformation technique, if it works.Only DNA, cells, and growth medium are required. So far, no other oscillatoriales member could be transformed by natural transformation. We hope that our studies stimulate other groups to try other oscillatoria.For transformation, make a good, healthy looking-culture and a good DNA preparation. For motion studies, always use an ultrasound-treated culture. Treatment should be fresh.Demonstrating the procedure will be Nora Weber, a technician from my laboratory. Begin by inoculating 50 milliliters liquid F2 medium into each of the two 250-milliliter flasks with one milliliter of P.lacuna filaments from a running culture. Cultivate in white light under agitation for around five days at 25 degrees Celsius.After five days, homogenize 100 milliliters of P.lacuna cell suspension at 10, 000 RPM for three minutes and measure the optical density at 750 nanometers. Then, centrifuge the cell suspension for 15 minutes at 6, 000 times G.Remove the supernatant and suspend the pellet in 800 microliters of the remaining liquid and additional F2+medium. Take eight F2+Bacto agar plates containing 120 micrograms per milliliter kanamycin and pipette 10 micrograms of DNA into the middle of each agar plate.Immediately pipette 100 microliters of the cell suspension on top of the DNA. Keep the agar plate without a lid on the clean bench to allow the excess liquid to evaporate. Close the plate and cultivate it in white light at 25 degrees Celsius for two days.After two days, distribute the filaments of each agar plate onto several fresh F2+Bacto agar plates containing 120 micrograms per milliliter kanamycin with an inoculation loop. Cultivate the plates in white light at 25 degrees Celsius and check the cultures regularly under a microscope. After 14 to 28 days, identify the dead brownish filaments and search for transformed filaments under the microscope.The transformed filaments look healthy and green and are different from the bulk of filaments. Transfer each single transformed filament into 50-milliliter flasks with 10 milliliters of F2+medium with 250 micrograms per milliliter kanamycin. Cultivate in white light at 25 degrees Celsius on a shaker and observe growth for up to four weeks.Transfer the filaments back to the agar medium containing 250 micrograms per milliliter kanamycin and wait for the filaments to grow. Then, increase the kanamycin concentration again to speed up the segregation. For GFP expression, observes single filaments with a fluorescence microscope at 40X or 63X magnification and capture a bright-field transmission image and a fluorescence image.Cultivate P.lacuna in F2 medium under 50 RPM horizontal agitation in white light for around five days until the estimated optical density at 750 nanometers becomes 0.35. Store the sample at four degrees Celsius. Homogenize the filaments with ultrasound for one minute at maximum power and cycle of one.Measure the optical density at 750 nanometers and transfer eight milliliters of the medium containing P.lacuna into a six-centimeter Petri dish. Wait for a few minutes until the sample reaches room temperature and then cover the Petri dish with cellophane foil. Place a microscope slide on the X-Y table of a standard microscope with a camera.Switch on the microscope light and move a 4X or 10X objective into the path of the light. Then, place the Petri dish on top of the slide. Adjust single filaments or filament bundles by the table's X, Y, and Z movements.Observe the movements of single filaments or bundles and record the movements with a standard microscope camera. Ensure that the objective lens does not touch the liquid. Pipette 0.5 milliliters of a solution containing P.lacuna on the Bacto agar surface of a six-centimeter Petri dish.Allow the liquid to enter the surface. After around 20 minutes, close the Petri dish and observe the movement of the filaments on the surface using a 4X or 10X objective. Capture the time lapse recordings using an ocular camera and a mini-computer system.The filaments must first be focused by eye and then through the ocular camera. Ensure that the time interval between the subsequent images is five seconds to one minute. Program the Linux script of the mini-computer to control the time lapse recording.Prepare LED holders where the five millimeter LEDs are mounted to irradiate an area of 20-millimeters square from below to above. Measure and adjust the LED intensities. Ensure that the whole setting is in a dark room or a closed, dark container.Place eight milliliters of the medium containing P.lacuna into a six-centimeter Petri dish, close the Petri dish with the lid, and place it on an LED holder so that the LED is in the center of the Petri dish. After typically two days, capture an image of the Petri dish with a smartphone camera aimed directly at the position of the light treatment. Use a holder and a white sheet as a background to ensure the same distance and light conditions for every picture.Open the ImageJ software, click on File, Open, and select the file. Then, click on Enter. Select the straight button and press the left mouse button to draw a line from one end of the Petri dish to the opposite end.Ensure that the line passes through the center of the circle of filaments. Click on Analyze and Measure to see the length of the Petri dish. Then, click on Analyze and Plot Profile in the ImageJ menu.Estimate an average value for the pixel intensity outside the circle and another average value for the pixel intensity inside the circle. Point the mouse on the Y position between these values to estimate the X values of both sides of the circle. Note both values and calculate the difference.Then select the straight button and draw a line at the mid-maximum value of the pixel intensity. Finally, click on Analyze and then Measure to get the length of the inner cell circle. Integration and segregation of insert after the transformation of P.lacuna with PAK1 is shown here.A PCR test with outer primers around one week after the transformation typically has two bands on the electrophoresis gel, one with the size of the wild-type band, and one slower migrating band that indicates the insertion of the resistance cassette. Here, lanes 1 to 4 represent PCR products of filaments after seven days, 11 days, 14 days, and 17 days of the isolation of a resistant filament, and lane 5 represents PCR product of wild-type. In the seven-day sample, the insert is present in a small fraction of the chromosomes.This fraction increases until 17 days, where no wild-type band is visible;that is, the segregation is complete. This image represents the vector pMH1 for sfGHP expression under the control of endogenous phycocyanin beta promoter. P.lacuna homologous sequence, pUC19 vector backbone, and insert with sfGFP and kanamycin resistance are shown here.In pMH1, the sfGHP gene is placed three prime of the phycocyanin beta gene;therefore, it is driven by the endogenous cpc beta promoter. Fluorescence images of P.lacuna wild-type filaments and after transformation with PAK1, PAK2, PAK3, and pMH1 are shown here. The expression of sfGFP is driven by the cpc 560 promoter, the a2813 promoter, the psbA2S promoter, or the endogenous cpc beta promoter.The merged images presented here show the motility of Phormidium lacuna. The movement on the agar surface is shown here. The time interval was one minute.The movement in the liquid medium is presented here. The time interval was 10 seconds. Natural transformation is a simple method.Just mix plasmid DNA with a resistance cassette in homologous sequences with the cells and let the cells grow on a medium with antibiotics. Genes can be inactivated and proteins can be overexpressed. This is important for any basic research and for biotechnical studies.In single-cell cyanobacteria where natural transformation is also established, molecular studies on photosynthesis or photoreceptors, et cetera, were addressed.

natural-transformation-protein-expression-cryoconservation

Research

JoVE Journal

Biology

The Preparation of Primary Hematopoietic Cell Cultures From Murine Bone Marrow for Electroporation

It is becoming increasingly apparent that electroporation is the most effective way to introduce plasmid DNA or siRNA into primary cells. The Gene Pulser MXcell  electroporation system and Gene Pulser  electroporation buffer were specifically developed to transfect nucleic acids into mammalian cells and difficult-to-transfect cells, such as primary and stem cells.This video demonstrates how to establish primary hematopoietic cell cultures from murine bone marrow, and then prepare them for electroporation in the MXcell system. We begin by isolating femur and tibia. Bone marrow from both femur and tibia are then harvested and cultures are established. Cultured bone marrow cells are then transfected and analyzed.

This procedure describes how to establish primary hematopoietic cell cultures from murine bone marrow and is followed by transfection using the Gene Pulser MXCell electroporation system.

It is becoming increasingly apparent that electroporation is the most effective way to introduce plasmid DNA or siRNA into primary cells. The Gene Pulser ...

Staining of Proteins in Gels with Coomassie G-250 without Organic Solvent and Acetic Acid

In classical protein staining protocols using Coomassie Brilliant Blue (CBB), solutions with high contents of toxic and flammable organic solvents (Methanol, Ethanol or 2-Propanol) and acetic acid are used for fixation, staining and destaining of proteins in a gel after SDS-PAGE. To speed up the procedure, heating the staining solution in the microwave oven for a short time is frequently used. This usually results in evaporation of toxic or hazardous Methanol, Ethanol or 2-Propanol and a strong smell of acetic acid in the lab which should be avoided due to safety considerations. In a protocol originally published in two patent applications by E.M. Wondrak (US2001046709 (A1), US6319720 (B1)), an alternative composition of the staining solution is described in which no organic solvent or acid is used. The CBB is dissolved in bidistilled water (60-80mg of CBB G-250 per liter) and 35 mM HCl is added as the only other compound in the staining solution. The CBB staning of the gel is done after SDS-PAGE and thorough washing of the gel in bidistilled water. By heating the gel during the washing and staining steps, the process can be finished faster and no toxic or hazardous compunds are evaporating. The staining of proteins occurs already within 1 minute after heating the gel in staining solution and is fully developed after 15-30 min with a slightly blue background that is destained completely by prolonged washing of the stained gel in bidistilled water, without affecting the stained protein bands.

A short protocol for protein staining with Coomassie Brilliant Blue (CBB) G-250 in polyacrylamide gels is described without using organic solvents or acetic acid as in the classical staining procedures with CBB.

In classical protein staining protocols using Coomassie Brilliant Blue (CBB), solutions with high contents of toxic and flammable organic solvents ...

Using the Gene Pulser MXcell Electroporation System to Transfect Primary Cells with High Efficiency

It is becoming increasingly apparent that electroporation is the most effective way to introduce plasmid DNA or siRNA into primary cells. The Gene Pulser MXcell electroporation system and Gene Pulser electroporation buffer (Bio-Rad) were specifically developed to easily transfect nucleic acids into mammalian cells and difficult-to-transfect cells, such as primary and stem cells. We will demonstrate how to perform a simple experiment to quickly identify the best electroporation conditions. We will demonstrate how to run several samples through a range of electroporation conditions so that an experiment can be conducted at the same time as optimization is performed. We will also show how optimal conditions identified using 96-well electroporation plates can be used with standard electroporation cuvettes, facilitating the switch from electroporation plates to electroporation cuvettes while maintaining the same electroporation efficiency. In the video, we will also discuss some of the key factors that can lead to the success or failure of electroporation experiments.

This procedure shows how to use the Gene Pulser MXcell electroporation system to rapidly and easily identify the best electroporation conditions for mouse embryonic fibroblasts (MEFs) or other primary cells. Considerations for troubleshooting are also discussed in the associated video.

Using the GELFREE 8100 Fractionation System for Molecular Weight-Based Fractionation with Liquid Phase Recovery

The GELFREE 8100 Fractionation System is a novel protein fractionation system designed to maximize protein recovery during molecular weight based fractionation. The system is comprised of single-use, 8-sample capacity cartridges and a benchtop GELFREE Fractionation Instrument. During separation, a constant voltage is applied between the anode and cathode reservoirs, and each protein mixture is electrophoretically driven from a loading chamber into a specially designed gel column gel. Proteins are concentrated into a tight band in a stacking gel, and separated based on their respective electrophoretic mobilities in a resolving gel. As proteins elute from the column, they are trapped and concentrated in liquid phase in the collection chamber, free of the gel. The instrument is then paused at specific time intervals, and fractions are collected using a pipette. This process is repeated until all desired fractions have been collected. If fewer than 8 samples are run on a cartridge, any unused chambers can be used in subsequent separations.
This novel technology facilitates the quick and simple separation of up to 8 complex protein mixtures simultaneously, and offers several advantages when compared to previously available fractionation methods. This system is capable of fractionating up to 1mg of total protein per channel, for a total of 8mg per cartridge. Intact proteins over a broad mass range are separated on the basis of molecular weight, retaining important physiochemical properties of the analyte. The liquid phase entrapment provides for high recovery while eliminating the need for band or spot cutting, making the fractionation process highly reproducible1.

The accompanying video describes the use of the GELFREE 8100 Fractionation System, which partitions complex protein samples on the basis of molecular weight and recovers the fractions in liquid phase. The video describes how the technology works, how it is used, and provides resultant data, with polyacrylamide gel electrophoresis analysis of fractionated bovine liver homogenate.

The GELFREE 8100 Fractionation System is a novel protein fractionation system designed to maximize protein recovery during molecular weight based ...

Floral-dip Transformation of Arabidopsis thaliana to Examine pTSO2::&beta;-glucuronidase Reporter Gene Expression

The ability to introduce foreign genes into an organism is the foundation for modern biology and biotechnology. In the model flowering plant Arabidopsis thaliana, the floral-dip transformation method1-2 has replaced all previous methods because of its simplicity, efficiency, and low cost. Specifically, shoots of young flowering Arabidopsis plants are dipped in a solution of Agrobacterium tumefaciens carrying specific plasmid constructs. After dipping, the plants are returned to normal growth and yield seeds, a small percentage of which are transformed with the foreign gene and can be selected for on medium containing antibiotics. This floral-dip method significantly facilitated Arabidopsis research and contributed greatly to our understanding of plant gene function. In this study, we use the floral-dip method to transform a reporter gene, &beta;-glucuronidase (GUS), under the control of TSO2 promoter. TSO2, coding for the Ribonucleotide Reductase (RNR) small subunit3, is a cell cycle regulated gene essential for dNDP biosynthesis in the S-phase of the cell cycle. Examination of GUS expression in transgenic Arabidopsis seedlings shows that TSO2 is expressed in actively dividing tissues. The reported experimental method and materials can be easily adapted not only for research but also for education at high school and college levels.

Floral-dip Transformation of Arabidopsis thaliana to Examine pTSO2::&#946;-glucuronidase Reporter Gene Expression

This article illustrates the floral-dip method of Agrobacterium tumefaciens -mediated transformation of Arabidopsis thaliana. By introducing a cell-cycle regulated promoter-reporter, pTSO2::&beta;-glucuronidase (GUS), into Arabidopsis, we illustrates how one detects GUS reporter expression in transgenic seedlings.

The ability to introduce foreign genes into an organism is the foundation for modern biology and biotechnology. In the model flowering plant Arabidopsis ...

Expression, Detergent Solubilization, and Purification of a Membrane Transporter, the MexB Multidrug Resistance Protein

Multidrug resistance (MDR), the ability of a cancer cell or pathogen to be resistant to a wide range of structurally and functionally unrelated anti-cancer drugs or antibiotics, is a current serious problem in public health. This multidrug resistance is largely due to energy-dependent drug efflux pumps. The pumps expel anti-cancer drugs or antibiotics into the external medium, lowering their intracellular concentration below a toxic threshold. We are studying multidrug resistance in Pseudomonas aeruginosa, an opportunistic bacterial pathogen that causes infections in patients with many types of injuries or illness, for example, burns or cystic fibrosis, and also in immuno-compromised cancer, dialysis, and transplantation patients. The major MDR efflux pumps in P. aeruginosa are tripartite complexes comprised of an inner membrane proton-drug antiporter (RND), an outer membrane channel (OMF), and a periplasmic linker protein (MFP) 1-8. The RND and OMF proteins are transmembrane proteins. Transmembrane proteins make up more than 30% of all proteins and are 65% of current drug targets. The hydrophobic transmembrane domains make the proteins insoluble in aqueous buffer. Before a transmembrane protein can be purified, it is necessary to find buffer conditions containing a mild detergent that enable the protein to be solubilized as a protein detergent complex (PDC) 9-11. In this example, we use an RND protein, the P. aeruginosa MexB transmembrane transporter, to demonstrate how to express a recombinant form of a transmembrane protein, solubilize it using detergents, and then purify the protein detergent complexes. This general method can be applied to the expression, purification, and solubilization of many other recombinantly expressed membrane proteins. The protein detergent complexes can later be used for biochemical or biophysical characterization including X-ray crystal structure determination or crosslinking studies.

In this protocol we demonstrate the expression, solubilization, and purification of a recombinantly expressed membrane protein, MexB, as a soluble protein detergent complex. MexB is a multidrug resistance membrane transporter from the opportunistic bacterial pathogen Pseudomonas aeruginosa.

Multidrug resistance (MDR), the ability of a cancer cell or pathogen to be resistant to a wide range of structurally and functionally unrelated ...

In vitro Reconstitution of the Active T. castaneum Telomerase

Efforts to isolate the catalytic subunit of telomerase, TERT, in sufficient quantities for structural studies, have been met with limited success for more than a decade. Here, we present methods for the isolation of the recombinant Tribolium castaneum TERT (TcTERT) and the reconstitution of the active T. castaneum telomerase ribonucleoprotein (RNP) complex in vitro.
Telomerase is a specialized reverse transcriptase1 that adds short DNA repeats, called telomeres, to the 3' end of linear chromosomes2 that serve to protect them from end-to-end fusion and degradation. Following DNA replication, a short segment is lost at the end of the chromosome3 and without telomerase, cells continue dividing until eventually reaching their Hayflick Limit4. Additionally, telomerase is dormant in most somatic cells5 in adults, but is active in cancer cells6 where it promotes cell immortality7.
The minimal telomerase enzyme consists of two core components: the protein subunit (TERT), which comprises the catalytic subunit of the enzyme and an integral RNA component (TER), which contains the template TERT uses to synthesize telomeres8,9. Prior to 2008, only structures for individual telomerase domains had been solved10,11. A major breakthrough in this field came from the determination of the crystal structure of the active12, catalytic subunit of T. castaneum telomerase, TcTERT1.
Here, we present methods for producing large quantities of the active, soluble TcTERT for structural and biochemical studies, and the reconstitution of the telomerase RNP complex in vitro for telomerase activity assays. An overview of the experimental methods used is shown in Figure 1.

In vitro Reconstitution of the Active T. castaneum Telomerase

Efforts to isolate the catalytic subunit of telomerase, TERT, in sufficient quantities for structural studies, have been met with limited success for more than a decade. Here, we present methods for the isolation of the recombinant Tribolium castaneum TERT (TcTERT) and the reconstitution of the active T. castaneum telomerase ribonucleoprotein (RNP) complex in vitro.

Efforts to isolate the catalytic subunit of telomerase, TERT, in sufficient quantities for structural studies, have been met with limited success for more ...

Expression and Purification of the Cystic Fibrosis Transmembrane Conductance Regulator Protein in Saccharomyces cerevisiae

The cystic fibrosis transmembrane conductance regulator (CFTR) is a chloride channel, that when mutated, can give rise to cystic fibrosis in humans.There is therefore considerable interest in this protein, but efforts to study its structure and activity have been hampered by the difficulty of expressing and purifying sufficient amounts of the protein1-3. Like many 'difficult' eukaryotic membrane proteins, expression in a fast-growing organism is desirable, but challenging, and in the yeast S. cerevisiae, so far low amounts were obtained and rapid degradation of the recombinant protein was observed 4-9. Proteins involved in the processing of recombinant CFTR in yeast have been described6-9 .In this report we describe a methodology for expression of CFTR in yeast and its purification in significant amounts. The protocol describes how the earlier proteolysis problems can be overcome and how expression levels of CFTR can be greatly improved by modifying the cell growth conditions and by controlling the induction conditions, in particular the time period prior to cell harvesting. The reagants associated with this protocol (murine CFTR-expressing yeast cells or yeast plasmids) will be distributed via the US Cystic Fibrosis Foundation, which has sponsored the research. An article describing the design and synthesis of the CFTR construct employed in this report will be published separately (Urbatsch, I.; Thibodeau, P. et al., unpublished). In this article we will explain our method beginning with the transformation of the yeast cells with the CFTR construct - containing yeast plasmid (Fig. 1). The construct has a green fluorescent protein (GFP) sequence fused to CFTR at its C-terminus and follows the system developed by Drew et al. (2008)10. The GFP allows the expression and purification of CFTR to be followed relatively easily. The JoVE visualized protocol finishes after the preparation of microsomes from the yeast cells, although we include some suggestions for purification of the protein from the microsomes. Readers may wish to add their own modifications to the microsome purification procedure, dependent on the final experiments to be carried out with the protein and the local equipment available to them. The yeast-expressed CFTR protein can be partially purified using metal ion affinity chromatography, using an intrinsic polyhistidine purification tag. Subsequent size-exclusion chromatography yields a protein that appears to be &gt;90% pure, as judged by SDS-PAGE and Coomassie-staining of the gel.

Expression and Purification of the Cystic Fibrosis Transmembrane Conductance Regulator Protein in Saccharomyces cerevisiae

Attempts to express the cystic fibrosis transmembrane conductance regulator (CFTR) in Saccharomyces cerevisiae have, until now, yielded relatively low amounts of protein. This protocol and the associated reagents distributed via the Cystic Fibrosis Foundation should allow the preparation of milligram amounts of this 'difficult' eukaryotic membrane protein.

The  cystic fibrosis transmembrane conductance regulator (CFTR) is a chloride  channel, that when mutated, can give rise to cystic fibrosis in  ...

Analysis of Global RNA Synthesis at the Single Cell Level following Hypoxia

Hypoxia or lowering of the oxygen availability is involved in many physiological and pathological processes. At the molecular level, cells initiate a particular transcriptional program in order to mount an appropriate and coordinated cellular response. The cell possesses several oxygen sensor enzymes that require molecular oxygen as cofactor for their activity. These range from prolyl-hydroxylases to histone demethylases. The majority of studies analyzing cellular responses to hypoxia are based on cellular populations and average studies, and as such single cell analysis of hypoxic cells are seldom performed. Here we describe a method of analysis of global RNA synthesis at the single cell level in hypoxia by using Click-iT RNA imaging kits in an oxygen controlled workstation, followed by microscopy analysis and quantification.&nbsp; Using cancer cells exposed to hypoxia for different lengths of time, RNA is labeled and measured in each cell. This analysis allows the visualization of temporal and cell-to-cell changes in global RNA synthesis following hypoxic stress.

We describe a technique for analysis of global RNA synthesis in hypoxia using imaging. Click-chemistry labeling of RNA has not previously been performed under hypoxia and allows visualization of global RNA changes at the single cell level. This approach complements the existing averaged RNA techniques, allowing direct visualization of cell-to-cell changes in global RNA synthesis.

Hypoxia or lowering of the oxygen availability is involved in many physiological and pathological processes. At the molecular level, cells initiate a ...

siRNA Screening to Identify Ubiquitin and Ubiquitin-like System Regulators of Biological Pathways in Cultured Mammalian Cells

Post-translational modification of proteins with ubiquitin and ubiquitin-like molecules (UBLs) is emerging as a dynamic cellular signaling network that regulates diverse biological pathways including the hypoxia response, proteostasis, the DNA damage response and transcription.&#160; To better understand how UBLs regulate pathways relevant to human disease, we have compiled a human siRNA &#8220;ubiquitome&#8221; library consisting of 1,186 siRNA duplex pools targeting all known and predicted components of UBL system pathways. This library can be screened against a range of cell lines expressing reporters of diverse biological pathways to determine which UBL components act as positive or negative regulators of the pathway in question.&#160; Here, we describe a protocol utilizing this library to identify ubiquitome-regulators of the HIF1A-mediated cellular response to hypoxia using a transcription-based luciferase reporter.&#160; An initial assay development stage is performed to establish suitable screening parameters of the cell line before performing the screen in three stages: primary, secondary and tertiary/deconvolution screening. &#160;The use of targeted over whole genome siRNA libraries is becoming increasingly popular as it offers the advantage of reporting only on members of the pathway with which the investigators are most interested.&#160; Despite inherent limitations of siRNA screening, in particular false-positives caused by siRNA off-target effects, the identification of genuine novel regulators of the pathways in question outweigh these shortcomings, which can be overcome by performing a series of carefully undertaken control experiments.

Here, we describe a methodology to perform a targeted siRNA &#8220;ubiquitome&#8221; screen to identify novel ubiquitin and ubiquitin-like regulators of the HIF1A-mediated cellular response to hypoxia.&#160; This can be adapted to any biological pathway where a robust read out of reporter activity is available.

Post-translational modification of proteins with ubiquitin and ubiquitin-like molecules (UBLs) is emerging as a dynamic cellular signaling network that ...