O trabalho foi financiado pela Fundação Sueca para a Pesquisa Ambiental Estratégica (MISTRA) através do programa DOM e Grant 211.684 (BACSIN) da Comunidade programa quadro europeu FP7 Union. Agradecemos J. Engstrand de assistência em filmar análise de raios-X e L. Tang para ajudar com a narrativa conceitual.

1. Cultivo e colheita de P. putida <ol><li> Prepara-se uma cultura iniciadora de Pseudomonas putida, por inoculação de 100 mL de caldo de soja tríptica (TSB) com uma colónia de P. putida células cultivadas em agar suplementado com caldo de soja tríptico (TSA). Manter a cultura a 30 ° C em uma placa de agitação fixada em 130 rpm. </li><li> Após 7 hr transferir uma parte alíquota da cultura iniciadora equivalente a 1/10 do volume final da cultura principal para TSB-meio fresco. Manter as células a 30 ° C em uma placa de agitação a 130 rpm durante 16 horas. </li><li> Após 16 horas de crescimento, as células são colhidas por fiação a cultura de células a 1.500 xg durante 20 min à temperatura ambiente. Decantar o sobrenadante e lava-se as células re-suspendendo a pelete celular é uma solução de NaCl que é isotónica com o meio de crescimento. Neste caso, foi utilizada uma solução de NaCl 150 mM. As células são, então, centrifugadas mais uma vez e o sobrenadante é decantado antes de ressuspensão das células em meio de formulação,veja o passo 3.2. </li></ol> 2. Cultivo de outras espécies <ol><li> Para adaptar o protocolo para outras espécies bacterianas os procedimentos de cultivo e colheita deve ser alterado de acordo com as exigências da espécie. Para evitar choque osmótico das células durante o manuseamento durante a colheita e a etapa de lavagem (s), a osmolalidade das soluções deve corresponder ao do meio de crescimento no momento da colheita. </li></ol> 3. Formulação de células <ol><li> Preparar as soluções de formulação por pesagem para os respectivos componentes da matriz e que se dissolvem em água. Para atingir as condições isotónicas, ou ajustar a quantidade de excipiente ou adicionar NaCl ou algum outro soluto compatível célula alcançar a osmolaridade desejada. Para as substâncias com baixo peso molecular, tais como as quantidades dissacarídeos pode ser facilmente ajustado para alcançar condições isotónicas. Para substâncias como polímeros que são de elevado peso molecular, a tonicidade deve ser ajustada de modo compatível com a célulaalaúdes, por exemplo, NaCl ou dissacarídeos. Note-se que a adição de qualquer substância irá influenciar as propriedades físicas da formulação, o que, por sua vez, podem influenciar o comportamento de secagem por congelação e sobrevivência celular. </li><li> Decantar a solução de lavagem (neste caso de NaCl) e re-suspender as células nos respectivos meios de formulação. </li><li> Certifique-se de que as células são homogeneamente dispersa. Formulações de baixa viscosidade são agitadas enquanto formulações de viscosidades mais elevadas são misturados usando pela adição, por ex., Uma barra de agitação e agitando o recipiente até que a mistura homogénea é atingida. </li><li> Separe as formulações em frascos liofilizador. Os frascos devem ser pesadas vazias, com a amostra antes e após a criodessecagem para calcular a quantidade de água removida durante a liofilização. </li><li> Adicionar rolhas de borracha para os frascos se os frascos devem ser selado dentro do liofilizador, consulte o passo 4.3. </li><li> Enumere as células em cada formulação antes da liofilização, consulte a etapa 6. </li> &lt;/ Ol&gt; 4. Liofilização <ol><li> As condições de secagem por congelação têm de ser ajustados para as propriedades físicas da formulação. O parâmetro mais importante é, neste caso, a temperatura de transição vítrea, Tg, da formulação, denotada Tg &#39;para a amostra crioconcentrada para indicar que a água ainda está presente. A Tg &#39;da formulação crioconcentrada é facilmente medida por calorimetria de varrimento diferencial (DSC), ver o passo 7. </li><li> Ajustar os parâmetros do processo de liofilização de modo a que a temperatura da amostra é sempre abaixo da Tg da amostra e que a pressão na câmara permite um rápido sublimação do gelo, ou seja, a secagem primária e a água residual na formulação, isto é, derivado secagem. Se a temperatura da amostra é acima da Tg &#39;, durante o processo de secagem não é um grande risco de colapso estrutural da amostra, que podem diminuir significativamente a sobrevivência celular. </li><li> Para proteger os produtos secos após freeze-secagem a atmosfera da amostra tem de ser controlada. Se possível, selar as amostras no liofilizador antes de o vácuo é libertado no final do ciclo de secagem por congelação. Alternativamente, os frascos podem ser preenchido com uma atmosfera preferido. É importante evitar a exposição das amostras para as condições ambientais como a humidade ou o oxigénio presente na atmosfera de armazenamento irão influenciar a sobrevivência das células. </li><li> Pesar os frascos. </li></ol> 5. Reidratação <ol><li> Rehidratar as amostras com água desionizada e estéril. A quantidade de água a ser adicionada deve ser a mesma que a quantidade removida durante a liofilização e é calculado a partir do peso do frasco vazio, o mesmo frasco com a amostra antes e após a liofilização. Vortex as amostras de vez em quando, em seguida, até as soluções aparecem homogênea. </li></ol> 6. Enumeração <ol><li> Desenhar 100 ul de cada amostra e fazer 10 diluições em série. A partir das diluições de inte100 l resto é revestida em placas de TSA. As placas são incubadas à temperatura e tempo requerido. </li></ol> 7. Caracterização da formulação do comportamento de congelamento <ol><li> Pegue uma pequena quantidade, 5 - 10 mg, da amostra e colocá-lo em uma panela DSC-alumínio com tampa. Prepare uma panela vazia como referência. </li><li> Definir o programa de verificação de temperatura DSC. O programa de arrefecimento é ajustado para imitar o passo de congelação no programa de liofilização. Isto é feito, como a cinética de arrefecimento pode influenciar a Tg &#39;das formulações hidratadas. Antes do exame de aquecimento começa reduzir a temperatura bem abaixo da Tg esperado &#39;das formulações investigadas, normalmente -100 ° C. </li><li> Escolher uma taxa adequada de aquecimento, normalmente, uma taxa de aquecimento de 5 - 40 ° C / min é usada. O sinal de fluxo de calor registada é expressa em watts e será influenciada pela taxa de aquecimento. A taxa de aquecimento maior irá dar um sinal maior de Tg. </li><li> Defina o intervalo de temperatura para que eut abrange tanto Tg &#39;ea fusão da formulação. </li></ol> 8. As medições de tensão de superfície das formulações hidratadas <ol><li> A configuração experimental utilizado nesta experiência é de acordo com o método para medir du NOUY superfície. </li><li> Limpar o anel de platina e o vaso de medição com cuidado. O navio é lavado com acetona, limpou com um pano que não solte fiapos, e depois queimado no interior com uma chama incolor. O anel brilha em vermelho em uma chama incolor. </li><li> Encha o copo com a solução e deixar a superfície resolver antes da medição. Para soluções, onde o estado de equilíbrio é atingido apenas após um longo período de tempo, por exemplo, polímeros, a configuração simples usado aqui irá fornecer dados qualitativos. </li><li> Para as formulações com elevadas viscosidades, por exemplo, soluções de 2% (w / w) de HEC ou HPMC, a tensão superficial tem de ser medida em soluções de concentrações mais baixas e, em seguida, extrapolada. Isto pode ser feito, aproveitando o factoà diminuição dos níveis de tensão superficial de folga em concentrações inferiores a 0,5% (w / w). </li></ol> 9. Análise de raios X das formulações secas <ol><li> Pegue uma pequena quantidade de matriz / bactérias e carregá-lo em um porta-amostras. </li><li> Monte o suporte de amostras para o X-ray-difratômetro. </li><li> Para analisar qualquer fase cristalina presente na amostra, o pacote de programas de EVA da Bruker pode ser usado. </li></ol> 10. Microscopia Eletrônica <ol><li> Pegue uma pequena quantidade de matriz / bactérias para fora dos frascos e corrigi-lo em um suporte de SEM. </li><li> Carregue o titular SEM no crepitar-coater (Thermo polaron VGScientific SC7640 utilizado no presente trabalho) e casaco da amostra com alguns nm de Au / Pd ou Pt. Nestas experiências, os parâmetros de pulverização foram: 1900 V, 20 mA, e 20 seg, para a ~ 5 - 10 nm revestimento Au / Pd. O revestimento reduz a carga elétrica, durante a aquisição da imagem. Recomenda-se começar com uma camada fina e, se o carregamento persiste e provoca imagemartefactos, a amostra deve ser revestido novamente. </li><li> Carregar o titular SEM SEM na câmara. Selecione os parâmetros de imagem apropriados. Para o instrumento utilizado na Figura 2 (FEI Strata DB235), foram utilizados 5 kV voltagem de aceleração, spotsize 3, a uma distância de trabalho de 5 mm e o detector de electrões secundários. </li><li> Opcionalmente, é possível a utilização de feixe de iões focado para cortar secções transversais das bactérias incorporados no polímero para revelar mais pormenores. </li></ol>

<ol>
	<li>Wessman, P., Mahlin, D., 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=Impact+of+matrix+properties+on+the+survival+of+freeze-dried+bacteria.">Impact of matrix properties on the survival of freeze-dried bacteria.</a> J. Sci. Food Agric. 91 (14), 2518-2528 (2011).</li><li>Ablett, S., Izzard, M. 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=Differential+Scanning+Calorimetric+Study+of+Frozen+Sucrose+and+Glycerol+Solutions.">Differential Scanning Calorimetric Study of Frozen Sucrose and Glycerol Solutions.</a> Journal of the Chemical Society-Faraday Transactions. 88 (6), 789-794 (1992).</li><li>Knopp, S. A., Chongprasert, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+relationship+between+type+TMDSC+curve+of+frozen+sucrose+solutions+and+collapse+during+freeze-drying.">The relationship between type TMDSC curve of frozen sucrose solutions and collapse during freeze-drying.</a> Journal of Thermal Analysis and Calorimetry. 54 (2), 659-672 (1998).</li><li>Crowe, J. H., Leslie, 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=Is+Vitrification+Sufficient+to+Preserve+Liposomes+during+Freeze-Drying.">Is Vitrification Sufficient to Preserve Liposomes during Freeze-Drying.</a> Cryobiology. 31 (4), 355-366 (1994).</li><li>Jain, P., Sen, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+glass-forming+biopreservatives+on+head+group+rotational+dynamics+in+freeze-dried+phospholipid+bilayers:+A+P-31+NMR+study.">Effect of glass-forming biopreservatives on head group rotational dynamics in freeze-dried phospholipid bilayers: A P-31 NMR study.</a> Journal of Chemical Physics. 131 (2), (2009).</li><li>Stock, J. B., Rauch, 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=Periplasmic+Space+in+Salmonella-Typhimurium+and+Escherichia-Coli.">Periplasmic Space in Salmonella-Typhimurium and Escherichia-Coli.</a> Journal of Biological Chemistry. 252 (21), 7850-7861 (1977).</li><li>Crowe, J. H., Hoekstra, F. A., 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=Anhydrobiosis.">Anhydrobiosis.</a> Annual Review of Physiology. 54, 579-599 (1992).</li><li>Leslie, S. B., Israeli, 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=Trehalose+and+Sucrose+Protect+Both+Membranes+and+Proteins+in+Intact+Bacteria+during+Drying.">Trehalose and Sucrose Protect Both Membranes and Proteins in Intact Bacteria during Drying.</a> Applied and Environmental Microbiology. 61 (10), 3592-3597 (1995).</li><li>Nesarikar, V. V., Nassar, M. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+cations+and+anions+on+glass+transition+temperatures+in+excipient+solutions.">Effect of cations and anions on glass transition temperatures in excipient solutions.</a> Pharmaceutical Development and Technology. 12 (3), 259-264 (2007).</li><li>You, Y., Ludescher, R. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+effect+of+sodium+chloride+on+molecular+mobility+in+amorphous+sucrose+detected+by+phosphorescence+from+the+triplet+probe+erythrosin+B.">The effect of sodium chloride on molecular mobility in amorphous sucrose detected by phosphorescence from the triplet probe erythrosin B.</a> Carbohydr. Res. 343 (2), 350-363 (2008).</li><li>Crowe, J. H., Hoekstra, F. A., Nguyen, K. H. N., Crowe, L. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Is+vitrification+involved+in+depression+of+the+phase+transition+temperature+in+dry+phospholipids.">Is vitrification involved in depression of the phase transition temperature in dry phospholipids.</a> Biochim. Biophys. Acta Biomembr. 1280, 187-196 (1996).</li></ol>

Não há conflitos de interesse declarados.

A motivação para este estudo foi investigar algumas propriedades de formulação que podem ser de grande importância para a sobrevivência da célula durante a liofilização. Embora a tolerância secagem intrínseco varia entre as diferentes espécies, tal como ilustrado na Figura 1A, a tendência de quão bem a formulações diferentes suporte a sobrevivência das células é semelhante. É informativo começar com uma comparação de sacarose e Ficoll. Acredita-se que um factor-chave para uma form...

<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>Ficoll PM 400</td>
			<td>GE-healthcare</td>
			<td>17-0300-10</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>HEC (Natrosol-M Pharm Grade)</td>
			<td>Ashland</td>
			<td>&nbsp;</td>
			<td>Gift from Ashland</td>
		</tr>
		<tr>
			<td>HPMC (Methocel F4M)</td>
			<td>Dow</td>
			<td>&nbsp;</td>
			<td>Gift from the Department of Pharmacy, Uppsala University</td>
		</tr>
		<tr>
			<td>Sucrose</td>
			<td>Sigma-Aldrich</td>
			<td>S2395</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>NaCl</td>
			<td>Sigma-Aldrich</td>
			<td>71376</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Tryptic Soy broth</td>
			<td>Merck</td>
			<td>105459</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Tryptic Soy Agar</td>
			<td>Merck</td>
			<td>105458</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Lyostar II</td>
			<td>FTS Kinetics</td>
			<td>N.A.</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Pyris Diamond DSC</td>
			<td>Perkin-Elmer</td>
			<td>N.A.</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Bruker AXS SMART CCD 1k Diffractometer</td>
			<td>Bruker</td>
			<td>N.A</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Dual-beam FEI Strata DB235 FIB/SEM</td>
			<td>FEI</td>
			<td>N.A</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Kr&uuml;ss Educational Tensiometer</td>
			<td>Kr&uuml;ss</td>
			<td>N.A.</td>
			<td>&nbsp;</td>
		</tr>
	</tbody>
</table>

formulations for freeze-drying of bacteria and their influence on cell survival

Cellular água pode ser removida para inactivar reversivelmente microorganismos para facilitar o armazenamento. Um tal método de remoção é a liofilização, que é considerado um método de desidratação suave. Para facilitar a sobrevivência das células durante a secagem, as células são frequentemente formuladas anteriormente. A formulação forma uma matriz que incorpora as células e protege-los a partir de várias tensões impostas nocivos sobre as células durante a congelação e secagem. Apresenta-se aqui um método geral para avaliar a taxa de sobrevivência das células após a liofilização e demonstramos pela comparação dos resultados obtidos com quatro formulações diferentes: a sacarose, o dissacárido sacarose derivada polímero Ficoll PM400, e os respectivos polissacáridos hidroxietil celulose (HEC ) e hidroxipropil-metil-celulose (HPMC), em duas estirpes de bactérias, P. putida KT2440 e A. A6 chlorophenolicus. Neste trabalho, ilustram como preparar formulações para liofilização e como para investigar o mecaismos de sobrevivência celular após a reidratação, caracterizando a formulação utilizando de calorimetria exploratória diferencial (DSC), medições de tensão superficial, análise de raios-X e microscopia eletrônica e relacionar esses dados com as taxas de sobrevivência. Os polímeros foram escolhidas para obter uma estrutura monomérica do respectivo polissacarídeo sacarose assemelhando-se a um em graus variados. Usando este método de instalação que mostrou que os polímeros podem suportar a sobrevivência celular tão eficazmente como dissacarídeos se certas propriedades físicas da formulação é controlada 1.

A Tabela 1 mostra dados sobre a composição da formulação, eventos gravados térmicas por DSC durante o aquecimento das formulações congeladas, a estrutura das amostras secas e a tensão superficial das soluções de formulação. A T g »de sacarose ter sido determinada a -40 ° C, 2, 3 e pode ser difícil de detectar concentrações de sacarose para abaixo de 20% w / w. A ocorrência térmica a -35 ° C, é, provavelmente, relacionado com o aparecimento de dissoluç...

Watch this Scientific Journal Video about Formulations for Freeze-drying of Bacteria and Their Influence on Cell Survival at JoVE.com

Formulations for Freeze-drying of Bacteria and Their Influence on Cell Survival

Liofilização é muitas vezes uma forma fácil e conveniente de obter produtos secos de células bacterianas viáveis. Uma questão do processo é a sobrevivência da célula. Nós detalhe aqui um processo para investigar a forma como a sobrevivência das células durante a liofilização é influenciada pelas propriedades da formulação utilizada.

As formulações para liofilização de bactérias e sua influência na sobrevivência das células

Cellular water can be removed to reversibly inactivate microorganisms to facilitate storage. One such method of removal is freeze-drying, which is ...

formulations-for-freeze-drying-bacteria-their-influence-on-cell

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23.2K visualizações.  Swedish University of Agricultural Sciences. Liofilização é muitas vezes uma forma fácil e conveniente de obter produtos secos de células bacterianas viáveis. Uma questão do processo é a sobrevivência da célula. Nós detalhe aqui um processo para investigar a forma como a sobrevivência das células durante a liofilização é influenciada pelas propriedades da formulação utilizada.

Vídeo: Formulations for Freeze-drying of Bacteria and Their Influence on Cell Survival

Obtaining Hemocytes from the Hawaiian Bobtail Squid Euprymna scolopes and Observing their Adherence to Symbiotic and Non-Symbiotic Bacteria

Studies concerning the role of the immune system in mediating molecular signaling between beneficial bacteria and their hosts have, in recent years, made significant contributions to our understanding of the co-evolution of eukaryotes with their microbiota. The symbiotic association between the Hawaiian bobtail squid, Euprymna scolopes and the bioluminescent bacterium Vibrio fischeri has been utilized as a model system for understanding the effects of beneficial bacteria on animal development. Recent studies have shown that macrophage-like hemocytes, the sole cellular component of the squid host's innate immune system, likely play an important role in mediating the establishment and maintenance of this association. This protocol will demonstrate how to obtain hemocytes from E. scolopes and then use these cells in bacterial binding assays. Adult squid are first anesthetized before hemolymph is collected by syringe from the main cephalic blood vessel. The host hemocytes, contained in the extracted hemolymph, are adhered to chambered glass coverslips and then exposed to green fluorescent protein-labeled symbiotic Vibrio fischeri and non-symbiotic Vibrio harveyi. The hemocytes are counterstained with a fluorescent dye (Cell Tracker Orange, Invitrogen) and then visualized using fluorescent microscopy.

Obtaining Hemocytes from the Hawaiian Bobtail Squid Euprymna scolopes and Observing their Adherence to Symbiotic and Non-Symbiotic Bacteria

This video will demonstrate how to obtain hemocytes (blood cells) from the Hawaiian bobtail squid, Euprymna scolopes for use in cell biological and bacterial adhesion assays. Hemocytes will be stained with a fluorescent dye and exposed to GFP-labeled bacteria.

Obtenção Hemócitos do Hawaiian Bobtail Squid Euprymna scolopes Observando e sua adesão a bactérias simbióticas e não-simbióticas

Studies concerning the role of the immune system in mediating molecular signaling between beneficial bacteria and their hosts have, in recent years, made ...

Biologia

Detection of Post-translational Modifications on Native Intact Nucleosomes by ELISA

The genome of eukaryotes exists as chromatin which contains both DNA and proteins. The fundamental unit of chromatin is the nucleosome, which contains 146 base pairs of DNA associated with two each of histones H2A, H2B, H3, and H41. The N-terminal tails of histones are rich in lysine and arginine and are modified post-transcriptionally by acetylation, methylation, and other post-translational modifications (PTMs). The PTM configuration of nucleosomes can affect the transcriptional activity of associated DNA, thus providing a mode of gene regulation that is epigenetic in nature 2,3. We developed a method called nucleosome ELISA (NU-ELISA) to quantitatively determine global PTM signatures of nucleosomes extracted from cells. NU-ELISA is more sensitive and quantitative than western blotting, and is useful to interrogate the epiproteomic state of specific cell types. This video journal article shows detailed procedures to perform NU-ELISA analysis.

Nucleosome ELISA (NU-ELISA) is a sensitive and quantitative method to detect global patterns of post-translational modifications in preparations of native, intact nucleosomes. These modifications include methylations, acetylations, and phosphorylations at specific histone amino acid residues, and hence NU-ELISA provides a global proteomic assay of the overall chromatin modification states of specific cell types.

Detecção de modificações pós-translacionais sobre Native Nucleossomos Intact por ELISA

The genome of eukaryotes exists as chromatin which contains both DNA and proteins. The fundamental unit of chromatin is the nucleosome, which contains 146 ...

Analyzing the Function of Small GTPases by Microinjection of Plasmids into Polarized Epithelial Cells

Epithelial cells polarize their plasma membrane into biochemically and functionally distinct apical and basolateral domains where the apical domain faces the 'free' surfaces and the basolateral membrane is in contact with the substrate and neighboring cells. Both membrane domains are separated by tight junctions, which form a diffusion barrier. Apical-basolateral polarization can be recapitulated successfully in culture when epithelial cells such as Madin-Darby Canine Kidney (MDCK) cells are seeded at high density on polycarbonate filters and cultured for several days 1 2. Establishment and maintenance of cell polarity is regulated by an array of small GTPases of the Ras superfamily such as RalA, Cdc42, Rab8, Rab10 and Rab13 3 4 5 6 7. Like all GTPases these proteins cycle between an inactive GDP-bound state and an active GTP-bound state. Specific mutations in the nucleotide binding regions interfere with this cycling 8. For example, Rab13T22N is permanently locked in the GDP-form and thus dubbed 'dominant negative', whereas Rab13Q67L can no longer hydrolyze GTP and is thus locked in a 'dominant active' state 7. To analyze their function in cells both dominant negative and dominant active alleles of GTPases are typically expressed at high levels to interfere with the function of the endogenous proteins 9. An elegant way to achieve high levels of overexpression in a short amount of time is to introduce the plasmids encoding the relevant proteins directly into the nuclei of polarized cells grown on filter supports using microinjection technique. This is often combined with the co-injection of reporter plasmids that encode plasma membrane receptors that are specifically sorted to the apical or basolateral domain. A cargo frequently used to analyze cargo sorting to the basolateral domain is a temperature sensitive allele of the vesicular stomatitis virus glycoprotein (VSVGts045) 10. This protein cannot fold properly at 39&deg;C and will thus be retained in the endoplasmic reticulum (ER) while the regulatory protein of interest is assembled in the cytosol. A shift to 31&deg;C will then allow VSVGts045 to fold properly, leave the ER and travel to the plasma membrane 11. This chase is typically performed in the presence of cycloheximide to prevent further protein synthesis leading to cleaner results. Here we describe in detail the procedure of microinjecting plasmids into polarized cells and subsequent incubations including temperature shifts that allow a comprehensive analysis of regulatory proteins involved in basolateral sorting.

This article details the procedures involved in overexpression and analysis of small GTPases in polarized epithelial cells using microinjection technique.

Analisando a função de GTPases Pequenas pela microinjeção de Plasmids em Polarized Células Epiteliais

Epithelial cells polarize their plasma membrane into biochemically and functionally distinct apical and basolateral domains where the apical domain faces ...

Single Cell Transcriptional Profiling of Adult Mouse Cardiomyocytes

While numerous studies have examined gene expression changes from homogenates of heart tissue, this prevents studying the inherent stochastic variation between cells within a tissue. Isolation of pure cardiomyocyte populations through a collagenase perfusion of mouse hearts facilitates the generation of single cell microarrays for whole transcriptome gene expression, or qPCR of specific targets using nanofluidic arrays. We describe here a procedure to examine single cell gene expression profiles of cardiomyocytes isolated from the heart. This paradigm allows for the evaluation of metrics of interest which are not reliant on the mean (for example variance between cells within a tissue) which is not possible when using conventional whole tissue workflows for the evaluation of gene expression (Figure 1). We have achieved robust amplification of the single cell transcriptome yielding micrograms of double stranded cDNA that facilitates the use of microarrays on individual cells. In the procedure we describe the use of NimbleGen arrays which were selected for their ease of use and ability to customize their design. Alternatively, a reverse transcriptase - specific target amplification (RT-STA) reaction, allows for qPCR of hundreds of targets by nanofluidic PCR. Using either of these approaches, it is possible to examine the variability of expression between cells, as well as examining expression profiles of rare cell types from within a tissue. Overall, the single cell gene expression approach allows for the generation of data that can potentially identify idiosyncratic expression profiles that are typically averaged out when examining expression of millions of cells from typical homogenates generated from whole tissues.

Single cell expression profiling allows the detailed gene expression analysis of individual cells. We describe methods for the isolation of cardiomyocytes, and preparing the resulting lysates for either whole transcriptome microarray or qPCR of specific targets.

Profiling única célula transcricional dos cardiomiócitos de rato adulto

While numerous studies have examined gene expression changes from homogenates of heart tissue, this prevents studying the inherent stochastic variation ...

Isolation and Culture of Individual Myofibers and their Satellite Cells from Adult Skeletal Muscle

Muscle regeneration in the adult is performed by resident stem cells called satellite cells. Satellite cells are defined by their position between the basal lamina and the sarcolemma of each myofiber. Current knowledge of their behavior heavily relies on the use of the single myofiber isolation protocol. In 1985, Bischoff described a protocol to isolate single live fibers from the Flexor Digitorum Brevis (FDB) of adult rats with the goal to create an in vitro system in which the physical association between the myofiber and its stem cells is preserved 1. In 1995, Rosenblattmodified the Bischoff protocol such that myofibers are singly picked and handled separately after collagenase digestion instead of being isolated by gravity sedimentation 2, 3. The Rosenblatt or Bischoff protocol has since been adapted to different muscles, age or conditions 3-6. The single myofiber isolation technique is an indispensable tool due its unique advantages. First, in the single myofiber protocol, satellite cells are maintained beneath the basal lamina. This is a unique feature of the protocol as other techniques such as Fluorescence Activated Cell Sorting require chemical and mechanical tissue dissociation 7. Although the myofiber culture system cannot substitute for in vivo studies, it does offer an excellent platform to address relevant biological properties of muscle stem cells. Single myofibers can be cultured in standard plating conditions or in floating conditions. Satellite cells on floating myofibers are subjected to virtually no other influence than the myofiber environment. Substrate stiffness and coating have been shown to influence satellite cells' ability to regenerate muscles 8, 9 so being able to control each of these factors independently allows discrimination between niche-dependent and -independent responses. Different concentrations of serum have also been shown to have an effect on the transition from quiescence to activation. To preserve the quiescence state of its associated satellite cells, fibers should be kept in low serum medium 1-3. This is particularly useful when studying genes involved in the quiescence state. In serum rich medium, satellite cells quickly activate, proliferate, migrate and differentiate, thus mimicking the in vivo regenerative process 1-3. The system can be used to perform a variety of assays such as the testing of chemical inhibitors; ectopic expression of genes by virus delivery; oligonucleotide based gene knock-down or live imaging. This video article describes the protocol currently used in our laboratory to isolate single myofibers from the Extensor Digitorum Longus (EDL) muscle of adult mice (6-8 weeks old).

Isolation and culture of myofibers is the gold standard in vitro system to study the transition of satellite cells through quiescence, activation and differentiation. Importantly, the single myofiber culture system preserves the myofiber/stem cell association, which is an essential component of the muscle stem cell niche.

Isolamento e Cultura de miofibras individuais e suas células satélites do músculo esquelético

Muscle  regeneration in the adult is performed by resident stem cells called satellite  cells. Satellite cells are defined by  their position between the ...

Strategies for Tracking Anastasis, A Cell Survival Phenomenon that Reverses Apoptosis

Anastasis (Greek for &#8220;rising to life&#8221;) refers to the recovery of dying cells. Before these cells recover, they have passed through important checkpoints of apoptosis, including mitochondrial fragmentation, release of mitochondrial cytochrome c into the cytosol, activation of caspases, chromatin condensation, DNA damage, nuclear fragmentation, plasma membrane blebbing, cell shrinkage, cell surface exposure of phosphatidylserine, and formation of apoptotic bodies. Anastasis can occur when apoptotic stimuli are removed prior to death, thereby allowing dying cells to reverse apoptosis and potentially other death mechanisms. Therefore, anastasis appears to involve physiological healing processes that could also sustain damaged cells inappropriately. The functions and mechanisms of anastasis are still unclear, hampered in part by the limited tools for detecting past events after the recovery of apparently healthy cells. Strategies to detect anastasis will enable studies of the physiological mechanisms, the hazards of undead cells in disease pathology, and potential therapeutics to modulate anastasis. Here, we describe effective strategies using live cell microscopy and a mammalian caspase biosensor&#160;for identifying and tracking anastasis in mammalian cells.

The term anastasis refers to the phenomenon in which dying cells reverse a cell suicide process at a late stage, repair themselves, and ultimately survive. Here we demonstrate protocols for detecting and tracking cells that undergo anastasis.

Estratégias para Rastreamento Anastasis, uma célula de sobrevivência Fenômeno que reverte apoptose

Anastasis (Greek for &#8220;rising to life&#8221;) refers to the recovery of dying cells. Before these cells recover, they have passed through important ...

A Standardized Method for the Analysis of Liver Sinusoidal Endothelial Cells and Their Fenestrations by Scanning Electron Microscopy

Liver sinusoidal endothelial cells are the gateway to the liver, their transcellular fenestrations allow the unimpeded transfer of small and dissolved substances from the blood into the liver parenchyma for metabolism and processing. Fenestrations are dynamic structures - both their size and/or number can be altered in response to various physiological states, drugs, and disease, making them an important target for modulation. An understanding of how LSEC morphology is influenced by various disease, toxic, and physiological states and how these changes impact on liver function requires accurate measurement of the size and number of fenestrations. In this paper, we describe scanning electron microscopy fixation and processing techniques used in our laboratory to ensure reproducible specimen preparation and accurate interpretation. The methods include perfusion fixation, secondary fixation and dehydration, preparation for the scanning electron microscope and analysis. Finally, we provide a step by step method for standardized image analysis which will benefit all researchers in the field.

The fenestrated liver sinusoidal endothelial cell is a biologically important filter system that is highly influenced by various diseases, toxins, and physiological states. These changes significantly impact on liver function. We describe methods for the standardisation of the measurement of the size and number of fenestrations in these cells.

Um método padronizado para a Análise do fígado sinusoidal células endoteliais e Seus fenestrações por Microscopia Eletrônica de Varredura

Liver sinusoidal endothelial cells are the gateway to the liver, their transcellular fenestrations allow the unimpeded transfer of small and dissolved ...

Measurement of Survival Time in Brachionus Rotifers: Synchronization of Maternal Conditions

Rotifers are microscopic cosmopolitan zooplankton used as models in ecotoxicological and aging studies due to their several advantages such as short lifespan, ease of culture, and parthenogenesis that enables clonal culture. However, caution is required when measuring their survival time as it is affected by maternal age and maternal feeding conditions. Here we provide a protocol for powerful and reproducible measurement of the survival time in Brachionus rotifers following a careful synchronization of culture conditions over several generations. Empirically, poor synchronization results in early mortality and a gradual decrease in survival rate, thus resulting in weak statistical power. Indeed, under such conditions, calorie restriction (CR) failed to significantly extend the lifespan of B. plicatilis although CR-induced longevity has been demonstrated with well-synchronized rotifer samples in past and present studies. This protocol is probably useful for other invertebrate models, including the fruitfly Drosophila melanogaster and the nematode Caenorhabditis elegans, because maternal age effects have also been reported in these species.

Measurement of Survival Time in Brachionus Rotifers: Synchronization of Maternal Conditions

Rotifers are microscopic zooplankton used as models in ecotoxicological and aging studies. Here we provide a protocol for powerful and reproducible measurement of survival time in Brachionus rotifers. Synchronization of culture conditions over several generations is of particular importance because maternal condition affects life history of offspring.

Measurement of Survival Time in<em&gt; Brachionus</em&gt; Rotifers: Sincronização de condições maternas

Rotifers are microscopic cosmopolitan zooplankton used as models in ecotoxicological and aging studies due to their several advantages such as short ...

Investigating the Detrimental Effects of Low Pressure Plasma Sterilization on the Survival of Bacillus subtilis Spores Using Live Cell Microscopy

Plasma sterilization is a promising alternative to conventional sterilization methods for industrial, clinical, and spaceflight purposes. Low pressure plasma (LPP) discharges contain a broad spectrum of active species, which lead to rapid microbial inactivation. To study the efficiency and mechanisms of sterilization by LPP, we use spores of the test organism Bacillus subtilis because of their extraordinary resistance against conventional sterilization procedures. We describe the production of B. subtilis spore monolayers, the sterilization process by low pressure plasma in a double inductively coupled plasma reactor, the characterization of spore morphology using scanning electron microscopy (SEM), and the analysis of germination and outgrowth of spores by live cell microscopy. A major target of plasma species is genomic material (DNA) and repair of plasma-induced DNA lesions upon spore revival is crucial for survival of the organism. Here, we study the germination capacity of spores and the role of DNA repair during spore germination and outgrowth after treatment with LPP by tracking fluorescently-labelled DNA repair proteins (RecA) with time-resolved confocal fluorescence microscopy. Treated and untreated spore monolayers are activated for germination and visualized with an inverted confocal live cell microscope over time to follow the reaction of individual spores. Our observations reveal that the fraction of germinating and outgrowing spores is dependent on the duration of LPP-treatment reaching a minimum after 120 s. RecA-YFP (yellow fluorescence protein) fluorescence was detected only in few spores and developed in all outgrowing cells with a slight elevation in LPP-treated spores. Moreover, some of the vegetative bacteria derived from LPP-treated spores showed an increase in cytoplasm and tended to lyse. The described methods for analysis of individual spores could be exemplary for the study of other aspects of spore germination and outgrowth.

Investigating the Detrimental Effects of Low Pressure Plasma Sterilization on the Survival of Bacillus subtilis Spores Using Live Cell Microscopy

This protocol illustrates the important consecutive steps required to assess the relevance of monitoring vitality parameter and DNA repair processes in reviving Bacillus subtilis spores after treatment with low pressure plasma by tracking fluorescence-labelled DNA repair proteins via time-resolved confocal microscopy and scanning electron microscopy.

Investigando os prejudiciais efeitos de baixa pressão Plasma esterilização na sobrevivência de esporos de Bacillus subtilis usando Live celular microscopia

Plasma sterilization is a promising alternative to conventional sterilization methods for industrial, clinical, and spaceflight purposes. Low pressure ...

Quantification of Site-specific Protein Lysine Acetylation and Succinylation Stoichiometry Using Data-independent Acquisition Mass Spectrometry

Post-translational modification (PTM) of protein lysine residues by N&#400;-acylation induces structural changes that can dynamically regulate protein functions, for example, by changing enzymatic activity or by mediating interactions. Precise quantification of site-specific protein acylation occupancy, or stoichiometry, is essential for understanding the functional consequences of both global low-level stoichiometry and individual high-level acylation stoichiometry of specific lysine residues. Other groups have reported measurement of lysine acetylation stoichiometry by comparing the ratio of peptide precursor isotopes from endogenous, natural abundance acylation and exogenous, heavy isotope-labeled acylation introduced after quantitative chemical acetylation of proteins using stable isotope-labeled acetic anhydride. This protocol describes an optimized approach featuring several improvements, including: (1) increased chemical acylation efficiency, (2) the ability to measure protein succinylation in addition to acetylation, and (3) improved quantitative accuracy due to reduced interferences using fragment ion quantification from data-independent acquisitions (DIA) instead of precursor ion signal from data-dependent acquisition (DDA). The use of extracted peak areas from fragment ions for quantification also uniquely enables differentiation of site-level acylation stoichiometry from proteolytic peptides containing more than one lysine residue, which is not possible using precursor ion signals for quantification. Data visualization in Skyline, an open source quantitative proteomics environment, allows for convenient data inspection and review. Together, this workflow offers unbiased, precise, and accurate quantification of site-specific lysine acetylation and succinylation occupancy of an entire proteome, which may reveal and prioritize biologically relevant acylation sites.

Here, we present unbiased quantification of site-specific protein acetylation and/or succinylation occupancy (stoichiometry) of an entire proteome through a ratiometric analysis of endogenous modifications to modifications introduced after quantitative chemical acylation using stable isotope-labeled anhydrides. In combination with sensitive data-independent acquisition mass spectrometry, accurate site occupancy measurements are obtained.

Quantificação de Estoicometria de Acetilação e Succinilação de Lisinas Proteicas em Sítios Específicos Usando Espectrometria de Massa de Aquisição de Dados Independente

Post-translational modification (PTM) of protein lysine residues by N&#400;-acylation induces structural changes that can dynamically regulate protein ...