Pesquisa foi financiada pelo NIH 1R15GM094770.

1. Isolamento colônia e Fixação <ol><li> Incubar 300 colônias em ágar durante o tempo indicado (uma colônia isolada deve ser 1-2 mm de diâmetro). </li><li> Remover colônia (viradas para cima) e médio subjacente usando uma espátula estreita. </li><li> Coloque algumas gotas de agar 2% 42 ° C em uma lâmina de microscópio utilizando 1 mL Pipetman ponta e imediatamente colônia lugar no rosto de agar-se antes que ela se solidifica. </li><li> Coloque algumas gotas de agar 2% 42 ° C na colônia e deixar solidificar. </li><li> Use luvas para todas as etapas até o final deste protocolo </li><li> Bloco guarnição com lâmina de barbear e colocá-los em um frasco de borosilicato 3,5 mL tampa de rosca contendo paraformaldeído 2% / fixador de glutaraldeído 2% por 7 dias a 4 ° C. </li></ol> 2. Lavagens e Tratamento Ósmio <ol><li> Após cerca de uma semana, lave blocos de ágar no gelo em química capela, incubando por duas vezes durante 15 minutos com cacodilato de sódio 0,15 M suficiente (pH 7,2) para cobrir completamente a colônia (aproximadamente 1,5 mL), em seguida, mais duas vezes durante 5 minutos com o mesmo volume de 1X OS tampão (100 mM KH 2 PO 4 10 mM MgCl 2, pH 6,0). </li><li> Adicionar o mesmo volume de OsO 1% 4 [2 mL OsO 4 (2%) + 2 mL de buffer 2x OS] para frascos (no gelo), para cobrir os blocos de agar com Cobertura de vapores químicos para uma hora depois lave duas vezes com a mesma quantidade OS de 1X tampão de 10 minutos cada. </li><li> Deixe os frascos durante a noite a 4 ° C em tampão 1X OS. </li><li> Fixador e todas as lavagens nesta etapa são eliminados como resíduos perigosos. Todas as pipetas contendo OsO 4 foram lavadas 3X com óleo vegetal. </li></ol> 3. Lavagem e desidratação <ol><li> Na manhã seguinte, lave blocos de agar duas vezes no gelo com o mesmo volume acima de água fria por 10 minutos cada um usando pipeta Pasteur. </li><li> Lavar seqüencialmente com o mesmo volume de 25%, 50%, 75%, etanol 95% por 10 minutos cada, seguidos de duas lavagens com etanol 100% por 10 minutos. Deixe overnight a 4 ° C em etanol 100%. </li><li> Todas as lavagens nesta etapa são eliminados como resíduos perigosos. </li></ol> 4. Preparação de Spurr <ol><li> Na manhã seguinte (o mais cedo possível) pesam as seguintes soluções (EM Sciences) em um copo plástico descartável sob uma coifa para preparar o reagente de Spurr. Para todo o trabalho subsequente utilizando este reagente, continuar a usar um exaustor. (ERL solução 4,221 5 gramas) (DER solução 736 4 gramas) (NSA solução 13 gramas) </li><li> mix dessas soluções (lentamente) por 20 minutos na capa usando uma barra de agitação </li><li> Adicionar solução de DMAE 0,15 gramas e agitar 20 minutos como acima. </li><li> Degas mistura acima para 1-2 hrs no capô. </li></ol> 5. Infiltração de Spurr <ol><li> Assim que Spurr é feita lavar blocos de agar 5 vezes com mesmo volume de etanol acima de 100 temp% ambiente por 10 minutos cada. Após a lavagem de etanol última remover o etanol utilizando uma pipeta Pasteur para que o etanol restantes apenas cobre os blocos de ágar. </li><li> Adicionar cerca de uma quantidade igual de reagente Spurr (aproximadamente 0,5 mL) e girar frascos na roda por 15 minutos em temperatura ambiente e, em seguida, deixar repousar por 30 minutos. Após 30 minutos retire a solução completamente usando uma pipeta de Pasteur, adicione Spurr para cobrir bloco agar (aproximadamente 1,5 mL), gire na roda de frascos por 15 minutos em temperatura ambiente e deixar repousar por 30 minutos. Repita a substituição Spurr, rotação e incubação de 3 vezes mais. </li><li> Após os 30 minutos finais, retire o reagente Spurr e adicionar novas Spurr para cobrir os blocos. Permitir que os blocos de agar para ficar à temperatura ambiente durante 4 horas. </li><li> Substituir a de Spurr e rodar durante a noite. </li><li> Na parte da manhã substituir Spurr e deixar rodar até o dia seguinte. </li><li> O lugar Spurr manhã seguinte, em moldes de silicone numeradas (Fisher Scientific) apenas para cobrir o fundo de moldes em seguida, adicione blocos agar para os moldes. Incubar a 60 ° C por 4 horas </li><li> Após 4 horas, top off os moldes, com mais Spurr e incubar a 60 ° C durante a noite. </li><li> Se depois de remover os blocos a partir de moldes dos blocos ainda estão um pouco flexível, volte para os moldes e incubar um período adicional de dois dias </li></ol> 6. Seccionamento <ol><li> Um micrótomo Leica Ultracut S foi usada para cortar 0,5 μ de espessura seções para microscopia de luz e 0,1 μ seções finas para EM transmissão. </li><li> Para microscopia de luz, como as seções foram cortadas, eles foram colocados em uma gota de dH 2 O, e secas em um bloco de aquecimento 52 ° C. Seções secas foram então coradas com uma gota de azul de toluidina 1,0%, borato de sódio 1% por 5-15 segundos. Após a coloração, os cortes foram imediatamente lavadas em uma corrente de água, secas, coberto de meios de montagem (KPL), e uma lamínula sobre a amostra selada. </li></ol> A grande relevância da formação de padrões de medição em leveduras e outros microorganismos foram revisadas anteriormente 1. Da nota particular é o maior funcionalidade de colônias microbianas organizadas em relação às comunidades desorganizado. O método descrito é uma modificação de um método para a incorporação de maiores colônias especializados 2, e uma breve descrição dos nossos modificações foi publicada 3. Um exemplo de uma micrografia luz de uma seção através do centro de uma colônia de S. selvagens colônia de levedura Saccharomyces é mostrado na Figura 1. Ascos, pseudo-ovóide e leveduras são facilmente distinguíveis, e na região da colônia invadindo o agar subjacente é aparente. Um exemplo de uma micrografia eletrônica de uma cepa de levedura de laboratório (W303 fundo) é mostrado na Figura 2. A imagem é de uma região da colônia contendo uma alta freqüência de células esporuladas. <img src="/files/ftp_upload/2510/2510fig1.jpg" alt="Figura 1" /> Figura 1. Microscopia de luz de uma colônia de leveduras selvagens. Esta levedura (YPS133) foi isolada recentemente de exsudatos árvore 4. A colônia foi incubada por 6 dias em média 5 yna antes do corte. Setas indicam aberta representante ascos, setas cheias indicam representante ovóide células vegetativas, pontas de flechas cheias indicam as cadeias de células alongadas (pseudo) e ascos. <img src="/files/ftp_upload/2510/2510fig2.jpg" alt="Figura 2" /> Figura 2. Microscopia eletrônica de uma cepa de levedura de laboratório. A colônia de SH1020 (W303 fundo) foi incubada por 6 dias em meio yna antes secção 3. A imagem mostra uma região da seção com uma alta freqüência de ascos. Uma seta indica a estrutura bi-layer da parede de esporos. <img src="/files/ftp_upload/2510/2510fig3.jpg" alt="Figura 3" /> Figura 3. Quantificação da distribuição de células esporuladas em colônias: A) uma grade contendo 15 retângulos adjacentes empilhados ao longo de seu lado mais longo é sobreposta à região central de uma imagem de uma seção de colônia. A grade é em escala, mantendo suas proporções constantes, apenas cobre a parte superior e inferior da colônia. (B &amp; C) A fração de células esporuladas em cada retângulo em relação ao total de células na retângulo que é determinado por inspeção visual de imagens de quatro dias de idade (B) e 8 dias de idade (C) colônias. Por exemplo, o retângulo na parte superior da colônia (identificado como &quot;1&quot;) corresponde ao lado esquerdo do gráfico. Média de quatro colônias é mostrada; as barras de erro exibir o std. erro.

<ol>
	<li>Kimmel, A. R., Firtel, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Breaking+symmetries:+regulation+of+Dictyostelium+development+through+chemoattractant+and+morphogen+signal-response.">Breaking symmetries: regulation of Dictyostelium development through chemoattractant and morphogen signal-response.</a> Curr Opin Genet Dev. 14, 540-540 (2004).</li><li>Palkova, Z., Vachova, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Life+within+a+community:+benefit+to+yeast+long-term+survival.">Life within a community: benefit to yeast long-term survival.</a> FEMS Microbiol Rev. 30, 806-806 (2006).</li><li>Shapiro, J., Vachova, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+significances+of+bacterial+colony+patterns.">The significances of bacterial colony patterns.</a> Bioessays. 17, 597-597 (1995).</li><li>Shapiro, J., Vachova, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Thinking+about+bacterial+populations+as+multicellular+organisms.">Thinking about bacterial populations as multicellular organisms.</a> Annu Rev Microbiol. 52, 81-81 (1998).</li><li>Engelberg, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Multicellular+stalk-like+structures+in+Saccharomyces+cerevisiae.">Multicellular stalk-like structures in Saccharomyces cerevisiae.</a> J Bacteriol. 180, 3992-3992 (1998).</li><li>Scherz, R., Shinder, V., Engelberg, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Anatomical+analysis+of+Saccharomyces+cerevisiae+stalk-like+structures+reveals+spatial+organization+and+cell+specialization.">Anatomical analysis of Saccharomyces cerevisiae stalk-like structures reveals spatial organization and cell specialization.</a> J Bacteriol. 183, 5402-5402 (2001).</li><li>Piccirillo, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Rim101p/PacC+pathway+and+alkaline+pH+regulate+pattern+formation+in+yeast+colonies.">The Rim101p/PacC pathway and alkaline pH regulate pattern formation in yeast colonies.</a> Genetics. 184, 707-707 (2010).</li><li>Sniegowski, P. D., Dombrowski, P. G., Fingerman, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Saccharomyces+cerevisiae+and+Saccharomyces+paradoxus+coexist+in+a+natural+woodland+site+in+North+America+and+display+different+levels+of+reproductive+isolation+from+European+conspecifics.">Saccharomyces cerevisiae and Saccharomyces paradoxus coexist in a natural woodland site in North America and display different levels of reproductive isolation from European conspecifics.</a> FEMS Yeast Res. 1, 299-299 (2002).</li><li>Piccirillo, S., Honigberg, S. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sporulation+patterning+and+invasive+growth+in+wild+and+domesticated+yeast+colonies.">Sporulation patterning and invasive growth in wild and domesticated yeast colonies.</a> Res Microbiol. 161, 390-390 (2002).</li><li>Vachova, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Architecture+of+developing+multicellular+yeast+colony:+spatio-temporal+expression+of+Ato1p+ammonium+exporter.">Architecture of developing multicellular yeast colony: spatio-temporal expression of Ato1p ammonium exporter.</a> Environ Microbiol. , (2009).</li></ol>

Não há conflitos de interesse declarados.

O método apresentado revela as estruturas interior das colônias. Porque o método é eficaz na determinação dos padrões de tipos de células em um intervalo de S. cepas cerevisiae com morfologias diferentes colônia, e também em uma espécie aparentada S. paradoxus 5, o método também é passível de trabalhar em uma grande variedade de fungos e outros microorganismos. Um passo crítico para o sucesso do método é garantir que toda a colônia, incluindo a...

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<td>Osmium tetroxide</td>
<td>&nbsp;</td>
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yeast colony embedding method

Padronização dos diferentes tipos de células de embriões é um mecanismo fundamental no desenvolvimento metazoários. Comunidades de microrganismos, tais como colônias e biofilmes também exibem padrões de tipos de células. Por exemplo, na levedura S. cerevisiae, células e células esporuladas pseudohyphal não são uniformemente distribuídos em colônias. A importância funcional da padronização e os mecanismos moleculares que fundamentam esses padrões ainda são pouco compreendidos. Um desafio que diz respeito à investigação de padrões de tipos de células em colônias de fungos é que, diferentemente do tecido metazoários, as células em colônias são relativamente fracamente ligados um ao outro. Em particular, colônias de fungos não contêm o mesmo nível extensivo de matriz extracelular encontrado na maioria dos tecidos. Aqui nós relatamos em um método para a incorporação e secção colônias de leveduras que revela o interior padrões de tipos de células nessas colônias. O método pode ser usado para preparar seções espessas (0,5 μ) úteis para microscopia de luz e cortes finos (0,1 μ) adequado para microscopia eletrônica de transmissão. Células ascos e pseudohyphal podem ser facilmente distinguidas das células de levedura ovóide por microscopia de luz, enquanto a estrutura interior destas células pode ser visualizado por EM. O método baseia-se em torno colônias com agar, infiltrando-los com o meio Spurr, e depois do corte. Colônias com um diâmetro na faixa de 1-2 mm são adequados para este protocolo. Além de visualizar o interior das colônias, o método permite a visualização da região da colônia, que invade o agar subjacente.

Watch this Scientific Journal Video about Yeast Colony Embedding Method at JoVE.com

Yeast Colony Embedding Method

Um método para a incorporação de colônias de leveduras permitindo o corte de microscopia óptica e eletrônica. Este protocolo permite a determinação da distribuição de células esporuladas e células pseudohyphal dentro colônias fornecendo uma nova ferramenta para a compreensão da organização de tipos de células dentro de uma comunidade de fungos.

Levedura Método Embedding Colony

Patterning of  different cell types in embryos is a key mechanism in metazoan development. Communities of microorganisms, such as colonies and biofilms ...

Research

JoVE Journal

Biology

11.4K visualizações.  University of Missouri - Kansas City. Um método para a incorporação de colônias de leveduras permitindo o corte de microscopia óptica e eletrônica. Este protocolo permite a determinação da distribuição de células esporuladas e células pseudohyphal dentro colônias fornecendo uma nova ferramenta para a compreensão da organização de tipos de células dentro de uma comunidade de fungos.

Vídeo: Yeast Colony Embedding Method

Measuring Replicative Life Span in the Budding Yeast

Aging is a degenerative process characterized by a progressive deterioration of cellular components and organelles resulting in mortality. The budding yeast Saccharomyces cerevisiae has been used extensively to study the biology of aging, and several determinants of yeast longevity have been shown to be conserved in multicellular eukaryotes, including worms, flies, and mice 1. Due to the lack of easily quantified age-associated phenotypes, aging in yeast has been assayed almost exclusively by measuring the life span of cells in different contexts, with two different life span paradigms in common usage 2. Chronological life span refers to the length of time that a mother cell can survive in a non-dividing, quiescence-like state, and is proposed to serve as a model for aging of post-mitotic cells in multicellular eukaryotes. Replicative life span, in contrast, refers the number of daughter cells produced by a mother cell prior to senescence, and is thought to provide a model of aging in mitotically active cells. Here we present a generalized protocol for measuring the replicative life span of budding yeast mother cells. The goal of the replicative life span assay is to determine how many times each mother cell buds. The mother and daughter cells can be easily differentiated by an experienced researcher using a standard light microscope (total magnification 160X), such as the Zeiss Axioscope 40 or another comparable model. Physical separation of daughter cells from mother cells is achieved using a manual micromanipulator equipped with a fiber-optic needle. Typical laboratory yeast strains produce 20-30 daughter cells per mother and one life span experiment requires 2-3 weeks.

In this article we present a general protocol for measuring the replicative life span of yeast mother cells.

Medição Span vida replicativa na levedura de brotamento

Aging is a degenerative process characterized by a progressive deterioration of cellular components and organelles resulting in mortality. The budding ...

Biologia

Purification of Mitochondria from Yeast Cells

Mitochondria are the main site of ATP production during aerobic metabolism in eukaryotic non-photosynthetic cells1. These complex organelles also play essential roles in apoptotic cell death2, cell survival3, mammalian development4, neuronal development and function4, intracellular signalling5, and longevity regulation6. Our understanding of these complex biological processes controlled by mitochondria relies on robust methods for assessing their morphology, their protein and lipid composition, the integrity of their DNA, and their numerous vital functions. The budding yeast Saccharomyces cerevisiae, a genetically and biochemically manipulable unicellular eukaryote with annotated genome and well-defined proteome, is a valuable model for studying the molecular and cellular mechanisms underlying essential biological functions of mitochondria. For these types of studies, it is crucial to have highly pure mitochondria. Here we present a detailed description of a rapid and effective method for purification of yeast mitochondria. This method enables the isolation of highly pure mitochondria that are essentially free of contamination by other organelles and retain their structural and functional integrity after their purification. Mitochondria purified by this method are suitable for cell-free reconstitution of essential mitochondrial processes and can be used for the analysis of mitochondrial structure and functions, mitochondrial proteome and lipidome, and mitochondrial DNA.

We describe a rapid and effective method for purification of mitochondria from the yeast Saccharomyces cerevisiae. This method enables the high-yield isolation of pure mitochondria that are essentially free of contamination by other organelles and retain their structural and functional integrity after their purification.

Purificação de mitocôndrias de células de levedura

Mitochondria are the main site of ATP production during aerobic metabolism in eukaryotic non-photosynthetic cells1. These complex organelles also play ...

High-throughput Yeast Plasmid Overexpression Screen

The budding yeast, Saccharomyces cerevisiae, is a powerful model system for defining fundamental mechanisms of many important cellular processes, including those with direct relevance to human disease. Because of its short generation time and well-characterized genome, a major experimental advantage of the yeast model system is the ability to perform genetic screens to identify genes and pathways that are involved in a given process. Over the last thirty years such genetic screens have been used to elucidate the cell cycle, secretory pathway, and many more highly conserved aspects of eukaryotic cell biology 1-5. In the last few years, several genomewide libraries of yeast strains and plasmids have been generated 6-10. These collections now allow for the systematic interrogation of gene function using gain- and loss-of-function approaches 11-16. Here we provide a detailed protocol for the use of a high-throughput yeast transformation protocol with a liquid handling robot to perform a plasmid overexpression screen, using an arrayed library of 5,500 yeast plasmids. We have been using these screens to identify genetic modifiers of toxicity associated with the accumulation of aggregation-prone human neurodegenerative disease proteins. The methods presented here are readily adaptable to the study of other cellular phenotypes of interest.

Here we describe a plasmid overexpression screen in Saccharomyces cerevisiae, using an arrayed plasmid library and a high-throughput yeast transformation protocol with a liquid handling robot.

Alto rendimento Yeast Tela superexpressão Plasmid

The budding yeast, Saccharomyces cerevisiae, is a powerful model system for defining fundamental mechanisms of many important cellular processes, ...

Competitive Genomic Screens of Barcoded Yeast Libraries

By virtue of advances in next generation sequencing technologies, we have access to new genome sequences almost daily. The tempo of these advances is accelerating, promising greater depth and breadth. In light of these extraordinary advances, the need for fast, parallel methods to define gene function becomes ever more important. Collections of genome-wide deletion mutants in yeasts and E. coli have served as workhorses for functional characterization of gene function, but this approach is not scalable, current gene-deletion approaches require each of the thousands of genes that comprise a genome to be deleted and verified. Only after this work is complete can we pursue high-throughput phenotyping. Over the past decade, our laboratory has refined a portfolio of competitive, miniaturized, high-throughput genome-wide assays that can be performed in parallel. This parallelization is possible because of the inclusion of DNA 'tags', or 'barcodes,' into each mutant, with the barcode serving as a proxy for the mutation and one can measure the barcode abundance to assess mutant fitness. In this study, we seek to fill the gap between DNA sequence and barcoded mutant collections. To accomplish this we introduce a combined transposon disruption-barcoding approach that opens up parallel barcode assays to newly sequenced, but poorly characterized microbes. To illustrate this approach we present a new Candida albicans barcoded disruption collection and describe how both microarray-based and next generation sequencing-based platforms can be used to collect 10,000 - 1,000,000 gene-gene and drug-gene interactions in a single experiment.

We have developed comprehensive, unbiased genome-wide screens to understand gene-drug and gene-environment interactions. Methods for screening these mutant collections are presented.

Competitiva Screens Genomic de Bibliotecas Yeast Barcoded

By virtue of advances in next generation sequencing technologies, we have access to new genome sequences almost daily.  The tempo of these advances is ...

A Quantitative Assay for Insulin-expressing Colony-forming Progenitors

The field of pancreatic stem and progenitor cell biology has been hampered by a lack of in vitro functional and quantitative assays that allow for the analysis of the single cell. Analyses of single progenitors are of critical importance because they provide definitive ways to unequivocally demonstrate the lineage potential of individual progenitors. Although methods have been devised to generate "pancreatospheres" in suspension culture from single cells, several limitations exist. First, it is time-consuming to perform single cell deposition for a large number of cells, which in turn commands large volumes of culture media and space. Second, numeration of the resulting pancreatospheres is labor-intensive, especially when the frequency of the pancreatosphere-initiating progenitors is low. Third, the pancreatosphere assay is not an efficient method to allow both the proliferation and differentiation of pancreatic progenitors in the same culture well, restricting the usefulness of the assay.
To overcome these limitations, a semi-solid media based colony assay for pancreatic progenitors has been developed and is presented in this report. This method takes advantage of an existing concept from the hematopoietic colony assay, in which methylcellulose is used to provide viscosity to the media, allowing the progenitor cells to stay in three-dimensional space as they undergo proliferation as well as differentiation. To enrich insulin-expressing colony-forming progenitors from a heterogeneous population, we utilized cells that express neurogenin (Ngn) 3, a pancreatic endocrine progenitor cell marker. Murine embryonic stem (ES) cell-derived Ngn3 expressing cells tagged with the enhanced green fluorescent protein reporter were sorted and as many as 25,000 cells per well were plated into low-attachment 24-well culture dishes. Each well contained 500 &mu;L of semi-solid media with the following major components: methylcellulose, Matrigel, nicotinamide, exendin-4, activin &beta;B, and conditioned media collected from murine ES cell-derived pancreatic-like cells. After 8 to 12 days of culture, insulin-expressing colonies with distinctive morphology were formed and could be further analyzed for pancreatic gene expression using quantitative RT-PCR and immunoflourescent staining to determine the lineage composition of each colony.
In summary, our colony assay allows easy detection and quantification of functional progenitors within a heterogeneous population of cells. In addition, the semi-solid media format allows uniform presentation of extracellular matrix components and growth factors to cells, enabling progenitors to proliferate and differentiate in vitro. This colony assay provides unique opportunities for mechanistic studies of pancreatic progenitor cells at the single cell level.

A three-dimensional clonogenic assay that allows pancreatic-like progenitors to differentiate into insulin-expressing colonies is described. This method takes advantage of semi-solid media containing methylcellulose, Matrigel and growth factors, in which single progenitors proliferate and differentiate in vitro, permitting quantification of the number of functional progenitors in a population.

Uma análise quantitativa para expressar Insulin-formadoras de colônias Progenitores

The field of pancreatic stem and progenitor cell biology has been hampered by a lack of in vitro functional and quantitative assays that allow for the ...

Chromatographic Purification of Highly Active Yeast Ribosomes

Eukaryotic ribosomes are much more labile as compared to their eubacterial and archael counterparts, thus posing a significant challenge to researchers. Particularly troublesome is the fact that lysis of cells releases a large number of proteases and nucleases which can degrade ribosomes. Thus, it is important to separate ribosomes from these enzymes as quickly as possible. Unfortunately, conventional differential ultracentrifugation methods leaves ribosomes exposed to these enzymes for unacceptably long periods of time, impacting their structural integrity and functionality. To address this problem, we utilize a chromatographic method using a cysteine charged Sulfolink resin. This simple and rapid application significantly reduces co-purifying proteolytic and nucleolytic activities, producing high yields of intact, highly biochemically active yeast ribosomes. We suggest that this method should also be applicable to mammalian ribosomes. The simplicity of the method, and the enhanced purity and activity of chromatographically purified ribosome represents a significant technical advancement for the study of eukaryotic ribosomes.

Contamination of preparations of eukaryotic ribosomes purified by traditional methods by co-purifying nucleases and proteases negatively impacts on downstream biochemical and structural analyses. A rapid and simple chromatographic purification method is used to solve this problem using yeast ribosomes as a model system.

Purificação cromatográfica de Ribossomos Yeast Highly Active

Eukaryotic ribosomes are much more labile as compared to their eubacterial and archael counterparts, thus posing a significant challenge to researchers.  ...

Cryosectioning Yeast Communities for Examining Fluorescence Patterns

Microbes typically live in communities. The spatial organization of cells within a community is believed to impact the survival and function of the community1. Optical sectioning techniques, including confocal and two-photon microscopy, have proven useful for observing spatial organization of bacterial and archaeal communities2,3. A combination of confocal imaging and physical sectioning of yeast colonies has revealed internal organization of cells4. However, direct optical sectioning using confocal or two-photon microscopy has been only able to reach a few cell layers deep into yeast colonies. This limitation is likely because of strong scattering of light from yeast cells4.
Here, we present a method based on fixing and cryosectioning to obtain spatial distribution of fluorescent cells within Saccharomyces cerevisiae communities. We use methanol as the fixative agent to preserve the spatial distribution of cells. Fixed communities are infiltrated with OCT compound, frozen, and cryosectioned in a cryostat. Fluorescence imaging of the sections reveals the internal organization of fluorescent cells within the community.
Examples of yeast communities consisting of strains expressing red and green fluorescent proteins demonstrate the potentials of the cryosectioning method to reveal the spatial distribution of fluorescent cells as well as that of gene expression within yeast colonies2,3. Even though our focus has been on Saccharomyces cerevisiae communities, the same method can potentially be applied to examine other microbial communities.

We present a protocol for freezing and cryosectioning yeast communities to observe internal patterns of fluorescent cells. The method relies on methanol-fixing and OCT-embedding to preserve the spatial distribution of cells without inactivating fluorescent proteins within a community.

Cryosectioning comunidades de leveduras para o exame de padrões de fluorescência

Microbes typically live  in communities. The spatial organization  of cells within a community is believed to impact the survival and function of the  ...

The Soft Agar Colony Formation Assay

Anchorage-independent growth is the ability of transformed cells to grow independently of a solid surface, and is a hallmark of carcinogenesis. The soft agar colony formation assay is a well-established method for characterizing this capability in vitro and is considered to be one of the most stringent tests for malignant transformation in cells. This assay also allows for semi-quantitative evaluation of this capability in response to various treatment conditions. Here, we will demonstrate the soft agar colony formation assay using a murine lung carcinoma cell line, CMT167, to demonstrate the tumor suppressive effects of two members of the Wnt signaling pathway, Wnt7A and Frizzled-9 (Fzd-9). Concurrent overexpression of Wnt7a and Fzd-9 caused an inhibition of colony formation in CMT167 cells. This shows that expression of Wnt7a ligand and its Frizzled-9 receptor is sufficient to suppress tumor growth in a murine lung carcinoma model.

The soft agar colony formation assay is a method used to confirm cellular anchorage-independent growth in vitro. The goal of this protocol is to illustrate a stringent method for the detection of the tumorigenic potential of transformed cells and the tumor suppressive effects of proteins on transformed cells.

A Formação Ensaio macio Agar Colony

Anchorage-independent growth is the ability of transformed cells to grow independently of a solid surface, and is a hallmark of carcinogenesis. The soft ...

Surface Spreading and Immunostaining of Yeast Chromosomes

The small size of nuclei of the budding yeast Saccharomyces cerevisiae limits the utility of light microscopy for analysis of the subnuclear distribution of chromatin-bound proteins. Surface spreading of yeast nuclei results in expansion of chromatin without loss of bound proteins. A method for surface spreading balances fixation of DNA bound proteins with detergent treatment. The method demonstrated is slightly modified from that described by Josef Loidl and Franz Klein1,2. The method has been used to characterize the localization of many chromatin-bound proteins at various stages of the mitotic cell cycle, but is especially useful for the study of meiotic chromosome structures such as meiotic recombinosomes and the synaptonemal complex. We also describe a modification that does not require use of Lipsol, a proprietary detergent, which was called for in the original procedure, but no longer commercially available. An immunostaining protocol that is compatible with the chromosome spreading method is also described.

A method for surface-spreading chromosomes from budding yeast is presented. This method is derived from a method previously described by Loidl and Klein. In addition, we demonstrate a procedure for immunostaining of spread chromosomes.

Espalhando superfície e Immunostaining de cromossomas da levedura

The small size of nuclei of the budding yeast Saccharomyces cerevisiae limits the utility of light microscopy for analysis of the subnuclear distribution ...

Microscopy of Fission Yeast Sexual Lifecycle

The fission yeast Schizosaccharomyces pombe has been an invaluable model system in studying the regulation of the mitotic cell cycle progression, the mechanics of cell division and cell polarity. Furthermore, classical experiments on its sexual reproduction have yielded results pivotal to current understanding of DNA recombination and meiosis. More recent analysis of fission yeast mating has raised interesting questions on extrinsic stimuli response mechanisms, polarized cell growth and cell-cell fusion. To study these topics in detail we have developed a simple protocol for microscopy of the entire sexual lifecycle. The method described here is easily adjusted to study specific mating stages. Briefly, after being grown to exponential phase in a nitrogen-rich medium, cell cultures are shifted to a nitrogen-deprived medium for periods of time suited to the stage of the sexual lifecycle that will be explored. Cells are then mounted on custom, easily built agarose pad chambers for imaging. This approach allows cells to be monitored from the onset of mating to the final formation of spores.

We provide a reproducible basic method for the long-term microscopy of the fission yeast sexual lifecycle. With minor adjustments described, the presented protocol allows research focus on different steps of the reproductive process.

Microscopia do ciclo de vida sexual por fissão de levedura

The fission yeast Schizosaccharomyces pombe has been an invaluable model system in studying the regulation of the mitotic cell cycle progression, the ...