This work was supported by National Eye Institute Grant R01 EY017724 (VMF) and National Institute of Arthritis and Musculoskeletal and Skin Diseases Grant K99 AR066534 (DSG).

Todos os procedimentos com animais foram realizados de acordo com as recomendações do Guia para o Cuidado e Uso de Animais de Laboratório pelos Institutos Nacionais de Saúde e sob um protocolo aprovado pelo Comitê de Cuidado e Uso Institucional animal no Scripps Research Institute. 1. Lens Dissection <ol><li> Euthanize camundongos acordo com as recomendações dos Institutos Nacionais de Saúde &quot;Guia para o Cuidado e Uso de Animais de Laboratório&quot; e protocolos de uso instituição animais aprovados. </li><li> Enuclear o olho de ratos usando uma pinça curva. Deprimir o tecido em volta do olho com a pinça para trazer o olho para fora da tomada, e depois arrancar o olho do soquete com a pinça. Transferir os olhos ao fosfato 1x salina fresca tamponada (PBS) no prato de dissecação. </li><li> Cortar o nervo óptico tão perto do globo ocular possível. Suavemente e com cuidado insira uma pinça reta finos no globo ocular através do wher buracoe o nervo óptico sai do posterior. </li><li> Cuidadosamente fazer uma incisão com tesoura no globo ocular a partir do posterior para o bordo da córnea. lentes de roedores ~ ocupar 30% do olho. Faça essas incisões cuidadosamente, e não introduza pinças ou tesouras muito profundo no olho para evitar danificar a lente. </li><li> O corte ao longo da junção entre a córnea e a esclera, pelo menos, a meio caminho em torno do globo ocular. </li><li> Com cuidado, empurre sobre a córnea para remover a lente do olho, através da abertura feita nas etapas 1.4 e 1.5. </li><li> Use uma pinça ponta reta finos para remover cuidadosamente qualquer grande detritos que ainda está ligado à lente. inspecionar visualmente a lente por qualquer dano antes de prosseguir com as medidas de rigidez. </li></ol> 2. Medidas de rigidez <ol><li> Pesar pelo menos 10 lamelas a partir da mesma caixa usando uma balança analítica. Encontre o peso médio das lamelas. Para consistência, use a mesma caixa de lamelas para todos os experimentos. Pré-molhadoAs lamelas e em ângulo recto espelho em 1x PBS à temperatura ambiente durante pelo menos duas horas antes de começar as experiências. </li><li> Encha a câmara de medição (ver Figura 1) com 65 - 75 ml de 1x PBS. A câmara de medição foi feita de Plexiglas por uma loja de máquina em casa, e divots na câmara foram feitas por uma imprensa de broca ajustado para a profundidade desejada com uma broca apropriada. Lentes permanecer transparente em 1x PBS, à temperatura ambiente, durante a duração do teste mecânico. </li></ol><img alt="figura 1" src="/files/ftp_upload/53986/53986fig1.jpg" /> Figura 1:. Rigidez Medição Secção Uma foto que mostra as dimensões da câmara de medição de rigidez feito por medida com uma variedade de torrões de diferentes profundidades e formas. Os divots redondas que são 200 mm ou 300 mm de profundidade (setas amarelas) são utilizados para as medições em lentes de rato. Divots são 2 mm de diâmetro e 13 ~-. 14 mm a partir da borda da câmara <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/53986/53986fig1large.jpg" target="_blank">Por favor clique aqui para ver uma versão maior desta figura.</a> <ol start="3"><li> Coloque espelho de ângulo direito para dentro da câmara a uma distância constante do torrão que vai ser usada para segurar a lente. Certifique-se o espelho não se move durante o experimento. </li><li> Transferência de lentes dissecados a câmara de medição com cuidado com apreensão fórceps ou pinças curvas. </li><li> Dê uma vista de cima imagem da lente descarregado directamente de cima. Tome rato fotos lente em 30X de ampliação com iluminação de microscópio de dissecação (inferior) e uma fonte de luz de fibra óptica nas laterais esquerda e direita. Definir a fonte de alimentação da fibra óptica a 80% da intensidade de luz máxima. Ajustar a saída da fonte de alimentação com base na iluminação ambiente, a preferência do usuário e qualidade de imagem, conforme necessário. </li><li> Dê uma vista lateral imagem da lente sem carga, o que pode ser visto através do riespelho GHT-ângulo. Se a câmera não está calibrado, tirar uma foto da borda do espelho no foco. A aresta do espelho é de 5 mm de comprimento, e essa medida pode depois ser usado para determinar a pixels / mm e servir como uma barra de escala nas imagens. </li><li> lente lugar no torrão, e confirme que a lente está sentado de forma segura e em linha reta no torrão. Tire uma foto da lente antes do carregamento. A lente deve estar descansando na torrão sobre o seu anterior ou pólo posterior. </li><li> Coloque uma lamela suavemente sobre a lente. Aguarde 2 min para permitir a fluência, e pegue outro lado-vista de imagem da lente carregado. </li><li> Continue adicionando lamelas como no passo 2.8 e tendo side-ver fotos após a adição de cada lamela como no passo 2.8 até um total de 10 lamelas são aplicadas. </li><li> Remova todas as lamelas. Aguarde 2 min, e dar uma visão lateral imagem da lente (dentro e fora do torrão) após a remoção de todas as lamelas. </li></ol> Medição 3. Lens Nucleus <ol><li> para determine o tamanho núcleo da lente, mover a lente para uma placa de Petri limpa preenchido com 1x PBS. </li><li> Gentilmente decapsulate a lente usando uma pinça reta finos. </li><li> Slough fora das células das fibras corticais por rolando a lente entre os dedos enluvados. O núcleo do cristalino remanescente vai se sentir como um mármore duro. Usar este procedimento para isolar o núcleo em lentes de adultos a partir de 1 mês de idade. Uma vez que o núcleo isolado é um corpo rígido, mais ensaios mecânica do núcleo da lente não pode ser executada utilizando este método descrito. </li><li> Lave o núcleo da lente em 1x PBS numa placa de Petri. </li><li> Coloque o núcleo da lente de volta para a câmara de medição (não no torrão), e tomar uma imagem do núcleo da lente através do espelho de ângulo direito. </li></ol><img alt="Figura 2" src="/files/ftp_upload/53986/53986fig2.jpg" /> Figura 2:. A Lenses mouse comprimido por Lamelas (A) Esquema e (B) fotografia do exconfiguração perimental mostrando uma lente de 2 meses de idade mouse em um torrão de 200 mm de profundidade na câmara de medição preenchida com 1x PBS. Um espelho ângulo direito e uma câmera digital acoplada a um microscópio de dissecação foram usadas para recolher imagens da lente durante a compressão por lamelas. (C) Fotos de pontos de vista sagital de um 2 meses de idade lente de tipo selvagem comprimido sucessivamente um número crescente de lamelas, desde que os dados brutos para medir diâmetros axiais e equatoriais e calculando tensões axiais e equatoriais durante o teste de compressão à base de lamela. A reflexão da lente pode, por vezes, ser visto nas lamelas (mais claramente visível na imagem uma lamela). Ao fazer medições, ignorar a reflexão e medir até o ápice da lente. (D) Fotos de pontos de vista sagital dos 2 meses de idade, do tipo selvagem lente pós-compressão eo núcleo isolado lente. A lente pós-compressão e núcleo isolado está sentado fora do torrão. Barras de escala, de 1 mm. Este valor é modificado a partir Gokhin, et al. PLoS ONE, 19, 2012. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/53986/53986fig2large.jpg" target="_blank">Por favor clique aqui para ver uma versão maior desta figura.</a> Análise 4. Imagem <ol><li> Medir diâmetros equatoriais e axiais de lentes antes do carregamento e após cada etapa de carregamento usando ImageJ ou software similar. Medir o diâmetro de cada núcleo da lente. O núcleo da lente é esférica de modo quase uma medição em qualquer orientação será suficiente 19,21. </li><li> Corrigir a lente axial diâmetros adicionando a profundidade do torrão utilizado. Na câmara de medição, o torrão obscurecido 200 uM (lentes de 2 meses de idade) ou de ratinho (300 um lentes de 4 meses de idade e 8 meses de idade) do rato da espessura axial da lente. </li><li> Calcule o axial e estirpes equatoriais a partir das medições do diâmetro da lente usando a equação, ε = (d - d 0) / d 0, onde ε é a tensão, d é a axial ou ediâmetro quatorial a uma determinada carga, e d é o diâmetro 0 axial ou equatorial correspondente a uma carga nula. </li><li> Traça-se a estirpes axial e equatorial como funções da carga aplicada (em mg). </li><li> Traçar a axial, equatorial e diâmetros nucleares. Calcular e traçar a relação de aspecto lente dividindo o diâmetro axial pelo diâmetro equatorial. </li><li> Calcular e definir o volume da lente usando a equação, Volume = 4/3 x π × 2 × R e R a, em que Re é o raio equatorial e R a é o raio medido a partir axial da fotografia tirada no passo 2.6. Esta equação assume a lente é um esferóide oblato (elipsóide) 1,22. </li><li> Calcular e definir o volume nuclear utilizando a equação, Volume = 4/3 x π × R 3 N, em que R N é o raio do núcleo da lente, conforme medido a partir da fotografia tirada no passo 3.5. Esta equação assume que o núcleo da lente iesfera sa 19,21. </li><li> Calcular e representar graficamente a fracção nuclear, tal como a razão do volume nuclear para o volume da lente. </li></ol>

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Os autores não têm nada para revelar.

Há várias considerações importantes quando se usa este método para medir a rigidez da lente. Em primeiro lugar, as lamelas são aplicados para a lente com um ângulo ligeiramente oblíquo (8-8,5 °) em relação ao fundo da câmara (θ). Isto aplica-se um componente muito pequeno da carga equatorial ao invés de axial. No entanto, essa carga equatorial é considerado insignificante, porque o pecado θ ≈ 0,1 19. Se este método é adaptado para lentes maiores, o ângulo das lamelas para o fundo da câma...

The lens is a transparent and avascular organ in the anterior chamber of the eye that is responsible for fine focusing of light onto the retina. A clear basement membrane, called the lens capsule, surrounds a bulk of elongated fiber cells covered by an anterior monolayer of epithelial cells1,2. Life-long growth of the lens depends on the continuous proliferation and differentiation of epithelial cells at the lens equator into new fiber cells that are added onto previous generations of fiber cells in a concentric manner2. Over time, lens fiber cells undergo compaction, resulting in a rigid center in the middle of the lens called the nucleus1. Accommodation, defined as a dioptric change in the optical power of the eye, occurs in humans when the ciliary muscles contract to deform the lens and allow a true increase in optical power to focus on near objects3-5. In the unaccommodated eye, the lens is held in a relatively flattened state due to tension from zonular fibers. When the ciliary muscles contract, the tension on the lens is released, leading to decreased lens equatorial diameter and increased axial thickness. Age-related changes in the lens cause presbyopia, a progressive loss of lens accommodation, which leads to the need for reading glasses. 
Several studies have linked presbyopia to age-related increase in the intrinsic stiffness of the lens6-11. Stiffness is defined as the resistance of an elastic object to deform under applied load. A variety of methods have been used to examine stiffness of human lenses, including spin compression12-14, actuator compression15, probe indentation16, dynamic mechanical analysis 6,10 and bubble-based acoustic radiation force17. While mouse lenses do not accommodate or develop presbyopia, mouse models for lens pathologies are valuable tools because mice are less expensive than larger animals, well characterized genetically and undergo accelerated age-related changes due to rapid aging. A handful of studies have examined mouse lens stiffness with compression methods and demonstrated changes in lens stiffness due to aging or targeted genetic disruptions18-21. Thus, mouse lenses are good models for studying age-related changes in lens stiffness. 
This protocol describes a simple and inexpensive, yet precise and reproducible, compression method for determining mouse lens stiffness based on application of glass coverslips onto the lens in conjunction with photographing the lens through a dissection microscope and mirror. This method yields robust strain and morphometric data with an easily fabricated and assembled apparatus. The representative results confirm that mouse lenses increase in stiffness with age.

<table border="0" cellpadding="0" cellspacing="0" width="811">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:361px;">Fine tip straight forceps</td>
			<td style="width:139px;">Fine Scientific Tools</td>
			<td style="width:119px;">11252-40</td>
			<td style="width:193px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Microdissection scissors, straight edge</td>
			<td style="width:139px;">Fine Scientific Tools</td>
			<td style="width:119px;">15000-00</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Curved forceps</td>
			<td style="width:139px;">Fine Scientific Tools</td>
			<td style="width:119px;">11272-40</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Seizing forceps</td>
			<td style="width:139px;">Hammacher</td>
			<td style="width:119px;">HSC 702-93</td>
			<td>Optional</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Dissection dish</td>
			<td style="width:139px;">Fisher Scientific</td>
			<td style="width:119px;">12565154</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">60mm petri dish</td>
			<td style="width:139px;">Fisher Scientific</td>
			<td style="width:119px;">0875713A</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">1X phosphate buffered saline (PBS)</td>
			<td style="width:139px;">Life Technologies</td>
			<td style="width:119px;">14190</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">18mm x 18mm glass coverslips</td>
			<td style="width:139px;">Fisher Scientific</td>
			<td style="width:119px;">12-542A</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Measurement chamber with divots to hold lenses</td>
			<td style="width:139px;"></td>
			<td style="width:119px;"></td>
			<td>Custom-made (see Figure 1)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Right-angle mirror</td>
			<td style="width:139px;">Edmund Optics</td>
			<td style="width:119px;">45-591</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Light source</td>
			<td style="width:139px;">Schott/Fostec</td>
			<td style="width:119px;">8375</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Illuminated dissecting microscope</td>
			<td style="width:139px;">Olympus</td>
			<td style="width:119px;">SZX-ILLD100</td>
			<td>With SZ-PT phototube</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Digital camera</td>
			<td style="width:139px;">Nikon</td>
			<td style="width:119px;">Coolpix 990</td>
			<td></td>
		</tr>
	</tbody>
</table>

sequential application of glass coverslips to assess the compressive stiffness of the mouse lens: strain and morphometric analyses

A lente do olho é um órgão transparente que refrata e focaliza a luz para formar uma imagem nítida sobre a retina. Nos seres humanos, os músculos ciliares contrato para deformar a lente, levando a um aumento na potência óptica das lentes para focar objetos próximos, um processo conhecido como acomodação. mudanças relacionadas à idade na rigidez da lente têm sido associados a presbiopia, uma redução na capacidade da lente para acomodar, e, por extensão, a necessidade de óculos de leitura. Mesmo que as lentes do mouse não acomodar ou desenvolver presbiopia, modelos de ratos pode fornecer uma ferramenta genética inestimável para patologias lente compreensão, eo envelhecimento acelerado observado em camundongos permite o estudo de mudanças relacionadas à idade na lente. Este protocolo demonstra um método simples, precisa e de custo eficaz para determinar a rigidez da lente do mouse, utilizando lamelas de vidro para aplicar sequencialmente crescente cargas de compressão na lente. Os dados representativos confirmar que as lentes do mouse se tornar mais rígida com a idade, comolentes humanas. Este método é altamente reprodutível e pode, potencialmente, ser ampliados por meios mecânicos lentes de teste a partir de animais maiores.

A rigidez e dimensões de lentes 2-, 4- e 8 meses de idade rato foram medidos. Os ratinhos foram todos os animais de tipo selvagem sobre um fundo puro estirpe C57BL6 obtido a partir da criação de animais Facilidade TSRI animal, e cada lente foi carregado com 1 a 10 lamelas. As estirpes axiais e equatoriais foram calculadas como uma função da carga aplicada através da medição do diâmetro equatorial e axial da lente após a adição de cada lamela, e depois normalizando a cada muda...

Watch this Scientific Journal Video about Sequential Application of Glass Coverslips to Assess the Compressive Stiffness of the Mouse Lens: Strain and Morphometric Analyses at JoVE.com

Sequential Application of Glass Coverslips to Assess the Compressive Stiffness of the Mouse Lens: Strain and Morphometric Analyses

Aplicação sequencial de lamelas de vidro para avaliar a compressão Rigidez do Lens Mouse: tensão e morfométricas Análises

Age-related increases in eye lens stiffness are linked to presbyopia. This protocol describes a simple, cost-effective method for measuring mouse lens stiffness. Mouse lenses, like human lenses, become stiffer with age. This method is precise and can be adapted for lenses from larger animals.

The eye lens is a transparent organ that refracts and focuses light to form a clear image on the retina. In humans, ciliary muscles contract to deform the ...

sequential-application-glass-coverslips-to-assess-compressive

Research

JoVE Journal

Biology

7.2K visualizações.  The Scripps Research Institute. Age-related increases in eye lens stiffness are linked to presbyopia. This protocol describes a simple, cost-effective method for measuring mouse lens stiffness. Mouse lenses, like human lenses, become stiffer with age. This method is precise and can be adapted for lenses from larger animals.

Vídeo: Sequential Application of Glass Coverslips to Assess the Compressive Stiffness of the Mouse Lens: Strain and Morphometric Analyses

Lens Transplantation in Zebrafish and its Application in the Analysis of Eye Mutants

The lens plays an important role in the development of the optic cup[1,2]. Using the zebrafish as a model organism, questions regarding lens development can be addressed. The zebrafish is useful for genetic studies due to several advantageous characteristics, including small size, high fecundity, short lifecycle, and ease of care. Lens development occurs rapidly in zebrafish. By 72 hpf, the zebrafish lens is functionally mature [3]. Abundant genetic and molecular resources are available to support research in zebrafish. In addition, the similarity of the zebrafish eye to those of other vertebrates provides basis for its use as an excellent animal model of human defects[4-7]. Several zebrafish mutants exhibit lens abnormalities, including high levels of cell death, which in some cases leads to a complete degeneration of lens tissues [8]. To determine whether lens abnormalities are due to intrinsic causes or to defective interactions with the surrounding tissues, transplantation of a mutant lens into a wild-type eye is performed. Using fire-polished metal needles, mutant or wild-type lenses are carefully dissected from the donor animal, and transferred into the host. To distinguish wild-type and mutant tissues, a transgenic line is used as the donor. This line expresses membrane-bound GFP in all tissues, including the lens. This transplantation technique is an essential tool in the studies of zebrafish lens mutants.

Lens development involves interactions with other tissues. Several zebrafish eye mutants are characterized by an abnormally small lens size. Here we demonstrate a lens transplantation experiment to determine whether this phenotype is due to intrinsic causes or defective interactions with tissues that surround the lens.

Transplante de lente em Zebrafish e sua Aplicação na Análise de Mutantes Eye

The lens plays an important role in the development of the optic cup[1,2]. Using the zebrafish as a model organism, questions regarding lens development ...

Biologia

Purification of the M. magneticum Strain AMB-1 Magnetosome Associated Protein MamA&Delta;41

Magnetotactic bacteria comprise a diverse group of aquatic microorganisms that are able to orientate themselves along geomagnetic fields. This behavior is believed to aid their search for suitable environments (1). This capability is conferred by the magnetosome, a subcellular organelle that consists of a linear-chain assembly of lipid vesicles each able to biomineralize and enclose a ~50-nm crystal of magnetite or greigite. A principle component of the magnetosome that was shown to be required for the formation of functional vesicles is MamA. MamA is a highly abundant magnetosome-associated protein which is one of the most characterized magnetosome-associated proteins in vivo (2-6). This article focuses on the purification of MamA, which despite being studied in vivo, no clear functional or structural details have been identified for it. Bioinformatics analysis suggested that MamA is a tetra-tricopeptide repeat (TPR) containing protein. TPR is a structural motif found as such or forming part of a bigger fold in a wide range of proteins, it serves as a template for protein-protein interactions and mediates multi-protein complexes (7). TPRs are involved in many crucial tasks in eukaryotic cell organelle processes and many bacterial pathways (8-14). In order to understand MamA, a unique TPR containing protein, highly purified protein is required as a first step. In this article, we present the purification protocol for a stable MamA deletion mutant (MamA&Delta;41) from M. magneticum AMB-1.

MamA is a unique Magnetosome associated protein which was shown to be involved in magnetosome activation. Here we present the purification protocol of MamA deletion mutant (MamA&Delta;41) from M. magneticum AMB-1.

Purificação do M. magneticum Strain AMB-1 proteína associada Magnetosome MamAΔ41

Magnetotactic bacteria comprise a diverse group of aquatic microorganisms that are able to orientate themselves along geomagnetic fields. This behavior is ...

Evisceration of Mouse Vitreous and Retina for Proteomic Analyses

While the mouse retina has emerged as an important genetic model for inherited retinal disease, the mouse vitreous remains to be explored. The vitreous is a highly aqueous extracellular matrix overlying the retina where intraocular as well as extraocular proteins accumulate during disease.1-3 Abnormal interactions between vitreous and retina underlie several diseases such as retinal detachment, proliferative diabetic retinopathy, uveitis, and proliferative vitreoretinopathy.1,4 The relative mouse vitreous volume is significantly smaller than the human vitreous (Figure 1), since the mouse lens occupies nearly 75% of its eye.5 This has made biochemical studies of mouse vitreous challenging. In this video article, we present a technique to dissect and isolate the mouse vitreous from the retina, which will allow use of transgenic mouse models to more clearly define the role of this extracellular matrix in the development of vitreoretinal diseases.

The dissection technique illustrates evisceration of the vitreous, retina, and lens from the mouse eye, separation by centrifugation, and characterization with protein assays.

Evisceração de Vítreo Mouse e Retina de Análises Proteômica

While the mouse retina has emerged as an important genetic model for inherited retinal disease, the mouse vitreous remains to be explored. The vitreous is ...

Biophysical Assays to Probe the Mechanical Properties of the Interphase Cell Nucleus: Substrate Strain Application and Microneedle Manipulation

In most eukaryotic cells, the nucleus is the largest organelle and is typically 2 to 10 times stiffer than the surrounding cytoskeleton; consequently, the physical properties of the nucleus contribute significantly to the overall biomechanical behavior of cells under physiological and pathological conditions. For example, in migrating neutrophils and invading cancer cells, nuclear stiffness can pose a major obstacle during extravasation or passage through narrow spaces within tissues.1 On the other hand, the nucleus of cells in mechanically active tissue such as muscle requires sufficient structural support to withstand repetitive mechanical stress. Importantly, the nucleus is tightly integrated into the cellular architecture; it is physically connected to the surrounding cytoskeleton, which is a critical requirement for the intracellular movement and positioning of the nucleus, for example, in polarized cells, synaptic nuclei at neuromuscular junctions, or in migrating cells.2 Not surprisingly, mutations in nuclear envelope proteins such as lamins and nesprins, which play a critical role in determining nuclear stiffness and nucleo-cytoskeletal coupling, have been shown recently to result in a number of human diseases, including Emery-Dreifuss muscular dystrophy, limb-girdle muscular dystrophy, and dilated cardiomyopathy.3 To investigate the biophysical function of diverse nuclear envelope proteins and the effect of specific mutations, we have developed experimental methods to study the physical properties of the nucleus in single, living cells subjected to global or localized mechanical perturbation. Measuring induced nuclear deformations in response to precisely applied substrate strain application yields important information on the deformability of the nucleus and allows quantitative comparison between different mutations or cell lines deficient for specific nuclear envelope proteins. Localized cytoskeletal strain application with a microneedle is used to complement this assay and can yield additional information on intracellular force transmission between the nucleus and the cytoskeleton. Studying nuclear mechanics in intact living cells preserves the normal intracellular architecture and avoids potential artifacts that can arise when working with isolated nuclei. Furthermore, substrate strain application presents a good model for the physiological stress experienced by cells in muscle or other tissues (e.g., vascular smooth muscle cells exposed to vessel strain). Lastly, while these tools have been developed primarily to study nuclear mechanics, they can also be applied to investigate the function of cytoskeletal proteins and mechanotransduction signaling.

We present two independent, microscope-based tools to measure the induced nuclear and cytoskeletal deformations in single, living adherent cells in response to global or localized strain application. These techniques are used to determine nuclear stiffness (i.e., deformability) and to probe intracellular force transmission between the nucleus and the cytoskeleton.

Ensaios biofísicos para investigar as propriedades mecânicas do núcleo da célula Interphase: Aplicação de substrato Strain e Manipulação de microagulhas

In most eukaryotic cells, the nucleus is the largest organelle and is typically 2 to 10 times stiffer than the surrounding cytoskeleton; consequently, the ...

Generation of Mice Derived from Induced Pluripotent Stem Cells

The production of induced pluripotent stem cells (iPSCs) from somatic cells provides a means to create valuable tools for basic research and may also produce a source of patient-matched cells for regenerative therapies. iPSCs may be generated using multiple protocols and derived from multiple cell sources. Once generated, iPSCs are tested using a variety of assays including immunostaining for pluripotency markers, generation of three germ layers in embryoid bodies and teratomas, comparisons of gene expression with embryonic stem cells (ESCs) and production of chimeric mice with or without germline contribution2. Importantly, iPSC lines that pass these tests still vary in their capacity to produce different differentiated cell types2. This has made it difficult to establish which iPSC derivation protocols, donor cell sources or selection methods are most useful for different applications.
The most stringent test of whether a stem cell line has sufficient developmental potential to generate all tissues required for survival of an organism (termed full pluripotency) is tetraploid embryo complementation (TEC)3-5. Technically, TEC involves electrofusion of two-cell embryos to generate tetraploid (4n) one-cell embryos that can be cultured in vitro to the blastocyst stage6. Diploid (2n) pluripotent stem cells (e.g. ESCs or iPSCs) are then injected into the blastocoel cavity of the tetraploid blastocyst and transferred to a recipient female for gestation (see Figure 1). The tetraploid component of the complemented embryo contributes almost exclusively to the extraembryonic tissues (placenta, yolk sac), whereas the diploid cells constitute the embryo proper, resulting in a fetus derived entirely from the injected stem cell line.
Recently, we reported the derivation of iPSC lines that reproducibly generate adult mice via TEC1. These iPSC lines give rise to viable pups with efficiencies of 5-13%, which is comparable to ESCs3,4,7 and higher than that reported for most other iPSC lines8-12. These reports show that direct reprogramming can produce fully pluripotent iPSCs that match ESCs in their developmental potential and efficiency of generating pups in TEC tests. At present, it is not clear what distinguishes between fully pluripotent iPSCs and less potent lines13-15. Nor is it clear which reprogramming methods will produce these lines with the highest efficiency. Here we describe one method that produces fully pluripotent iPSCs and "all- iPSC" mice, which may be helpful for investigators wishing to compare the pluripotency of iPSC lines or establish the equivalence of different reprogramming methods.

Generating induced pluripotent stem cell (iPSC) lines produces lines of differing developmental potential even when they pass standard tests for pluripotency. Here we describe a protocol to produce mice derived entirely from iPSCs, which defines the iPSC lines as possessing full pluripotency1.

Geração de camundongos derivadas de células-tronco pluripotentes induzidas

The production of induced pluripotent stem cells (iPSCs) from somatic cells provides a means to create valuable tools for basic research and may also ...

Gap Junctional Intercellular Communication: A Functional Biomarker to Assess Adverse Effects of Toxicants and Toxins, and Health Benefits of Natural Products

This protocol describes a scalpel loading-fluorescent dye transfer (SL-DT) technique that measures intercellular communication through gap junction channels, which is a major intercellular process by which tissue homeostasis is maintained. Interruption of gap junctional intercellular communication (GJIC) by toxicants, toxins, drugs, etc. has been linked to numerous adverse health effects. Many genetic-based human diseases have been linked to mutations in gap junction genes. The SL-DT technique is a simple functional assay for the simultaneous assessment of GJIC in a large population of cells. The assay involves pre-loading cells with a fluorescent dye by briefly perturbing the cell membrane with a scalpel blade through a population of cells. The fluorescent dye is then allowed to traverse through gap junction channels to neighboring cells for a designated time. The assay is then terminated by the addition of formalin to the cells. The spread of the fluorescent dye through a population of cells is assessed with an epifluorescence microscope and the images are analyzed with any number of morphometric software packages that are available, including free software packages found on the public domain. This assay has also been adapted for in vivo studies using tissue slices from various organs from treated animals. Overall, the SL-DT assay can serve a broad range of in vitro pharmacological and toxicological needs, and can be potentially adapted for high throughput set-up systems with automated fluorescence microscopy imaging and analysis to elucidate more samples in a shorter time.

This protocol describes a scalpel loading-fluorescent dye transfer technique that measures intercellular communication through gap junction channels. Gap junctional intercellular communication is a major cellular process by which tissue homeostasis is maintained and disruption of this cell signaling has adverse health effects.

Gap juncional intercelular comunicação: um biomarcador funcional para avaliar os efeitos adversos de tóxicos e toxinas, e Benefícios para a saúde de produtos naturais

This protocol describes a scalpel loading-fluorescent dye transfer (SL-DT) technique that measures intercellular communication through gap junction ...

Measuring the Stiffness of Ex Vivo Mouse Aortas Using Atomic Force Microscopy

Arterial stiffening is a significant risk factor and biomarker for cardiovascular disease and a hallmark of aging. Atomic force microscopy (AFM) is a versatile analytical tool for characterizing viscoelastic mechanical properties for a variety of materials ranging from hard (plastic, glass, metal, etc.) surfaces to cells on any substrate. It has been widely used to measure the stiffness of cells, but less frequently used to measure the stiffness of aortas. In this paper, we will describe the procedures for using AFM in contact mode to measure the ex vivo elastic modulus of unloaded mouse arteries. We describe our procedure for isolation of mouse aortas, and then provide detailed information for the AFM analysis. This includes step-by-step instructions for alignment of the laser beam, calibration of the spring constant and deflection sensitivity of the AFM probe, and acquisition of force curves. We also provide a detailed protocol for data analysis of the force curves.

Measuring the Stiffness of Ex Vivo Mouse Aortas Using Atomic Force Microscopy

We present detailed protocols for isolation of aortas from mouse and measurement of their elastic modulus using atomic force microscopy.

Medindo a rigidez<em&gt; Ex Vivo</em&gt; Mouse aortas Usando Microscopia de Força Atômica

Arterial stiffening is a significant risk factor and biomarker for cardiovascular disease and a hallmark of aging. Atomic force microscopy (AFM) is a ...

A Morphometric and Cellular Analysis Method for the Murine Mandibular Condyle

The temporomandibular joint (TMJ) has the capacity to adapt to external stimuli, and loading changes can affect the position of condyles, as well as the structural and cellular components of the mandibular condylar cartilage (MCC). This manuscript describes methods for analyzing these changes and a method for altering the loading of the TMJ in mice (i.e., compressive static TMJ loading). The structural evaluation illustrated here is a simple morphometric approach that uses the Digimizer software and is performed in radiographs of small bones. In addition, the analysis of cellular changes leading to alterations in collagen expression, bone remodeling, cell division, and proteoglycan distribution in the MCC is described. The quantification of these changes in histological sections - by counting the positive fluorescent pixels using image software and measuring the distance mapping and stained area with Digimizer - is also demonstrated. The methods shown here are not limited to the murine TMJ, but could be used on additional bones of small experimental animals and in other regions of endochondral ossification.

This manuscript presents methods for analyzing morphometric and cellular changes within the mandibular condyle of rodents.

Um método de análise celular para o côndilo Mandibular murino e morfométricas

The temporomandibular joint (TMJ) has the capacity to adapt to external stimuli, and loading changes can affect the position of condyles, as well as the ...

Lens-free Video Microscopy for the Dynamic and Quantitative Analysis of Adherent Cell Culture

Here, we demonstrate that lens-free video microscopy enables us to simultaneously capture the kinetics of thousands of cells directly inside the incubator and that it is possible to monitor and quantify single cells along several cell cycles. We describe the full protocol used to monitor and quantify a HeLa cell culture for 2.7 days. First, cell culture acquisition is performed with a lens-free video microscope, and then the data is analyzed following a four-step process: multi-wavelength holographic reconstruction, cell-tracking, cell segmentation and cell division detection algorithms. As a result, we show that it is possible to gather a dataset featuring more than 10,000 cell cycle tracks and more than 2 x 106 cell morphological measurements.

Lens-free video microscopy enables us to monitor cell cultures directly inside the incubator. Here we describe the full protocol used to acquire and analyze a 2.7 day long acquisition of cultured HeLa cells, leading to a dataset of 2.2 x 106 measurements of individual cell morphology and 10584 cell cycle tracks.

Lente livre de microscopia para a dinâmica e a análise quantitativa de cultura de células aderentes

Here, we demonstrate that lens-free video microscopy enables us to simultaneously capture the kinetics of thousands of cells directly inside the incubator ...

Application of Electrophysiology Measurement to Study the Activity of Electro-Neutral Transporters

The transport of ions through cell membranes ensures the fine control of ion content within and outside the cell that is indispensable for cell survival. These transport mechanisms are mediated by the activities of specialized transporter proteins. Specifically,pH dynamics are finely controlled by plasma membrane proton (H+) extrusion systems, such as the Na+/H+ exchanger (NHE) protein family. Despite extensive efforts to study the mechanisms underlying NHE regulation, our current understanding of the biophysical and molecular properties of the NHE family is inadequate because of the limited availability of methods to effectively measure NHE activity. In this manuscript, we used H+-selective electrodes during whole-cell patch clamping recording to measure NHE-induced H+ flux. We proposed this approach to overcome some limitations of typically used methods to measure NHE activity, such as radioactive uptake and fluorescent membrane permeants. Measurement of NHE activity using the described method enables high sensitivity and time resolution and more efficient control of intracellular H+ concentrations. H+-selective electrodes are based on the fact that transporter activity creates an ion gradient in close proximity to the cell membrane. An H+-selective electrode moving up to and away from the cell membrane in a repetitive, oscillatory fashion records a voltage difference that is dependent on H+ flux. While H+-selective electrodes are used to detect H+ flux moving out of the cell, the patch clamp method in the whole-cell configuration is used to control the intracellular ion composition. Moreover, application of the giant patch clamp technique allows modification of the intracellular composition of not only ions but also lipids. The transporter activity of NHE isoform 3 (NHE3) was measured using this technical approach to study the molecular basis of NHE3 regulation by phosphoinositides.

This manuscript describes the applications of proton-selective electrodes and patch clamping methods to measure the activity of proton transport systems. These methods overcome some limitations of techniques commonly used to study proton transport activity, such as moderate sensitivity, time resolution and insufficient intracellular milieu control.

Aplicação de medida de eletrofisiologia para estudar a atividade de transportadores de Electro-neutro

The transport of ions through cell membranes ensures the fine control of ion content within and outside the cell that is indispensable for cell survival. ...