Name: continuous high-resolution microscopic observation of replicative aging in budding yeast
Uploaded: 2013-08-20T13:00:00
Description: Watch this Scientific Journal Video about Continuous High-resolution Microscopic Observation of Replicative Aging in Budding Yeast at JoVE.com

We would like to thank Laura Schippers for writing the first versions of the cell loading protocol and Marcus de Goffau and Guille Zampar for scoring mitochondrial morphologies.

1. Production and Preparation of a Silicon Wafer Mold
Microfluidic chips are created from a silicon wafer mold produced by soft lithography. These wafers can be reused many times to produce microfluidic chips. It is advisable that production of a respective wafer is performed by a group specialized in microfluidics6.
The wafer is made in a two-step photolithography process using two different layers of negative photoresist, SU-87. The bottom laye...

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The microfluidic method described here is an important novel tool in aging research as it enables simple and automated generation of yeast replicative lifespan data in combination with continuous high resolution imaging. These attributes are major improvements over the experimental possibilities of the classical dissection method, yet there are a few limitations of the method that need to be taken into account.
Note that the determined replicative lifespan can be affected by the efficiency of ...

Budding yeast is an important model organism for aging research1. Until recently studying replicative aging in yeast cells was a laborious process requiring a dissection method, in which each bud was manually removed from the mother cell2,3. To solve this problem, we recently presented a novel microfluidic setup able to track individual mother cells throughout their entire lifespan4.
In our microfluidic chip, yeast cells are trapped under soft elastomer-based micropads (see Figure 1). A continuous flow of medium washes away newly formed daughter cells and provides the cells with fresh nutrients. In a single experiment, up to 50 mother cells can be monitored in a fully automated manner throughout their entire replicative lifespan. Due to the excellent optical properties of the microfluidic chip, it is possible to simultaneously monitor different aspects of yeast cell biology (e.g. by using fluorescent proteins).
 
Compared to the classical dissection method, the microfluidic setup provides substantial advantages. It ensures a defined and constant environment during the whole aging experiment. It requires no expensive specialized equipment and can be run on any microscope equipped with automated focus and time-lapse abilities as well as temperature-control for cell cultivation. The production and operation of the microfluidic chips can be learned within a few days. In addition, cells can be directly loaded from an exponentially growing culture, an advantage over another recently published microfluidic method5, which requires biotinylation of mother cells.a Combined with high-resolution imaging, the here described method can be used to measure gradual changes in cellular morphology, protein expression and localization during yeast aging in an unprecedented manner. The capability for long-term monitoring of single cells also provides unique possibilities for yeast cell cycle studies.
aThis method has recently been optimized to remove the biotinylation from the protocol16, which was published while this manuscript was in review.

<table border="1">
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 <td>Name </td>
 <td>Company </td>
 <td>Catalogue number </td>
 <td>Comments </td>
 </tr>
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 <td></td>
 <td></td>
 <td></td>
 <td>REAGENTS</td>
 </tr>
 <tr>
 <td>DC Sylgard 184 elastomer </td>
 <td>Mavom bv </td>
 <td>1060040 </td>
 <td>This package contains PDMS base and PDMS curing agent.</td>
 </tr>
 <tr>
 <td>Glass Petri dishes 120/20 mm </td>
 <td>VWR International </td>
 <td>391-2850 </td>
 <td></td>
 </tr>
 <tr>
 <td>Cover glasses 22x40 mm </td>
 <td>CBN Labsuppliers BV </td>
 <td>190002240 </td>
 <td></td>
 </tr>
 <tr>
 <td>Tough-Tags </td>
 <td>Sigma-Aldrich </td>
 <td>Z359106 </td>
 <td></td>
 </tr>
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 <td>Aluminum foil </td>
 <td></td>
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 <td>Plastic disposable cup </td>
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 <td>Serological pipette 5 ml </td>
 <td>VWR International </td>
 <td>612-1245 </td>
 <td></td>
 </tr>
 <tr>
 <td>Scotch tape </td>
 <td>VWR International </td>
 <td>819-1460 </td>
 <td></td>
 </tr>
 <tr>
 <td>Baysilone paste (GE Bayer silicones) </td>
 <td>Sigma-Aldrich </td>
 <td>85403-1EA </td>
 <td></td>
 </tr>
 <tr>
 <td>PTFE microbore tubing, 0.012"ID x 0.030"OD </td>
 <td>Cole Parmer </td>
 <td>EW-06417-11 </td>
 <td>Referred to as thin tubing </td>
 </tr>
 <tr>
 <td>Tygon microbore Tubing, 0.030"ID x 0.090"OD </td>
 <td>Cole Parmer </td>
 <td>EW-06418-03 </td>
 <td>Referred to as thick tubing </td>
 </tr>
 <tr>
 <td>Scalpel </td>
 <td>VWR International </td>
 <td>233-5334 </td>
 <td></td>
 </tr>
 <tr>
 <td>50 ml Luer-Lok syringes </td>
 <td>BD </td>
 <td>300137 </td>
 <td></td>
 </tr>
 <tr>
 <td>5 ml syringes, Luer tip </td>
 <td>VWR International </td>
 <td>613-1599 </td>
 <td></td>
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 <td>Tweezers </td>
 <td>VWR International </td>
 <td>232-2132 </td>
 <td></td>
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 <td>20 Gauge Luer stubs </td>
 <td>Instech Solomon </td>
 <td>LS20 </td>
 <td></td>
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 <td>Syringe filters (pore size 0.20 &mu;m) </td>
 <td>Sigma-Aldrich </td>
 <td>16534K </td>
 <td></td>
 </tr>
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 <td>Stainless steel catheter Plug, 20 ga x12 mm </td>
 <td>Instech Solomon </td>
 <td>SP20/12 </td>
 <td></td>
 </tr>
 <tr>
 <td>Petri dishes </td>
 <td>VWR International </td>
 <td>391-0892 </td>
 <td></td>
 </tr>
 <tr>
 <td></td>
 <td></td>
 <td></td>
 <td> EQUIPMENT</td>
 </tr>
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 <td>Benchtop UV-Ozone Cleaner </td>
 <td>NOVA Scan </td>
 <td>PSD-UVT </td>
 <td></td>
 </tr>
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 <td>Harvard Pump 11 Elite </td>
 <td>Harvard Apparatus </td>
 <td>70-4505 </td>
 <td></td>
 </tr>
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 <td>SU-8 silicon master mold (wafer) </td>
 <td></td>
 <td></td>
 <td>Self-made; For details contact corresponding author </td>
 </tr>
 <tr>
 <td>Balance </td>
 <td>Sartorius corporation </td>
 <td>ED4202S </td>
 <td></td>
 </tr>
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 <td>Vacuum pump </td>
 <td>KNF Neuberger </td>
 <td>N022 AN.18 </td>
 <td></td>
 </tr>
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 <td>Desiccator </td>
 <td>VWR International </td>
 <td>467-2115 </td>
 <td></td>
 </tr>
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 <td>Hot plate </td>
 <td>VWR International </td>
 <td>460-3267 </td>
 <td></td>
 </tr>
 <tr>
 <td>Optional: Metal holder for cover glass (22x40 mm) </td>
 <td></td>
 <td></td>
 <td>Self-made; For details contact corresponding author </td>
 </tr>
 <tr>
 <td>(Fluorescence) Microscope with 60x objective, autofocus, time-lapse abilities and preferably an automated (motorized XY control) stage </td>
 <td>Nikon </td>
 <td>Eclipse Ti-E </td>
 <td></td>
 </tr>
 </tbody>
</table>

continuous high-resolution microscopic observation of replicative aging in budding yeast

We demonstrate the use of a simple microfluidic setup, in which single budding yeast cells can be tracked throughout their entire lifespan. The microfluidic chip exploits the size difference between mother and daughter cells using an array of micropads. Upon loading, cells are trapped underneath these micropads, because the distance between the micropad and cover glass is similar to the diameter of a yeast cell (3-4 &mu;m). After the loading procedure, culture medium is continuously flushed through the chip, which not only creates a constant and defined environment throughout the entire experiment, but also flushes out the emerging daughter cells, which are not retained underneath the pads due to their smaller size. The setup retains mother cells so efficiently that in a single experiment up to 50 individual cells can be monitored in a fully automated manner for 5 days or, if necessary, longer. In addition, the excellent optical properties of the chip allow high-resolution imaging of cells during the entire aging process.

In this protocol, cells are loaded into the microfluidic chip directly from mid-exponential culture. To ascertain whether the age distribution of cells trapped in the microfluidic chip is similar to that of the culture prior to loading, cells were stained with wheat agglutinin conjugated to FITC (WGA-FITC) to visualize bud scars. As can be seen in Figure 3, the entrapment of cells under the micropads of the microfluidic chip is not biased to cells of a certain age.
Replicative...

Watch this Scientific Journal Video about Continuous High-resolution Microscopic Observation of Replicative Aging in Budding Yeast at JoVE.com

Continuous High-resolution Microscopic Observation of Replicative Aging in Budding Yeast

We describe here the operation of a microfluidic device that allows continuous and high-resolution microscopic imaging of single budding yeast cells during their complete replicative and/or chronological lifespan.

We demonstrate the use of a simple microfluidic setup, in which single budding yeast cells can be tracked throughout their entire lifespan. The ...

continuous-high-resolution-microscopic-observation-replicative-aging

Research

JoVE Journal

Bioengineering

High-resolution Fiber-optic Microendoscopy for in situ Cellular Imaging

Many biological and clinical studies require the longitudinal study and analysis of morphology and function with cellular level resolution. Traditionally, multiple experiments are run in parallel, with individual samples removed from the study at sequential time points for evaluation by light microscopy. Several intravital techniques have been developed, with confocal, multiphoton, and second harmonic microscopy all demonstrating their ability to be used for imaging in situ 1. With these systems, however, the required infrastructure is complex and expensive, involving scanning laser systems and complex light sources. Here we present a protocol for the design and assembly of a high-resolution microendoscope which can be built in a day using off-the-shelf components for under US$5,000. The platform offers flexibility in terms of image resolution, field-of-view, and operating wavelength, and we describe how these parameters can be easily modified to meet the specific needs of the end user.
We and others have explored the use of the high-resolution microendoscope (HRME) in in vitro cell culture 2-5, in excised 6 and living animal tissues 2,5, and in human tissues in vivo 2,7. Users have reported the use of several different fluorescent contrast agents, including proflavine 2-4, benzoporphyrin-derivative monoacid ring A (BPD-MA) 5, and fluoroscein 6,7, all of which have received full, or investigational approval from the FDA for use in human subjects. High-resolution microendoscopy, in the form described here, may appeal to a wide range of researchers working in the basic and clinical sciences. The technique offers an effective and economical approach which complements traditional benchtop microscopy, by enabling the user to perform high-resolution, longitudinal imaging in situ.

High-resolution Fiber-optic Microendoscopy for in situ Cellular Imaging

In many biological and clinical situations it is advantageous to study cellular processes as they evolve in their native microenvironment. Here we describe the assembly and use of a low-cost fiber-optic microscope which can provide real time imaging in cell culture, animal studies, and clinical patient studies.

Many biological and clinical studies require the longitudinal study and analysis of morphology and function with cellular level resolution.  ...

High Resolution 3D Imaging of Ex-Vivo Biological Samples by Micro CT

Non-destructive volume visualization can be achieved only by tomographic techniques, of which the most efficient is the x-ray micro computerized tomography (&mu;CT).
High resolution &mu;CT is a very versatile yet accurate (1-2 microns of resolution) technique for 3D examination of ex-vivo biological samples1, 2. As opposed to electron tomography, the &mu;CT allows the examination of up to 4 cm thick samples. This technique requires only few hours of measurement as compared to weeks in histology. In addition, &mu;CT does not rely on 2D stereologic models, thus it may complement and in some cases can even replace histological methods3, 4, which are both time consuming and destructive. Sample conditioning and positioning in &mu;CT is straightforward and does not require high vacuum or low temperatures, which may adversely affect the structure. The sample is positioned and rotated 180&deg; or 360&deg;between a microfocused x-ray source and a detector, which includes a scintillator and an accurate CCD camera, For each angle a 2D image is taken, and then the entire volume is reconstructed using one of the different available algorithms5-7. The 3D resolution increases with the decrease of the rotation step. The present video protocol shows the main steps in preparation, immobilization and positioning of the sample followed by imaging at high resolution.

High Resolution 3D Imaging of Ex-Vivo Biological Samples by Micro CT

Non-destructive volume visualization can be achieved only by tomographic techniques, of which the most efficient is the x-ray micro computerized tomography ( CT).

Non-destructive volume visualization can be achieved only by tomographic techniques, of which the most efficient is the x-ray micro computerized ...

High-resolution Spatiotemporal Analysis of Receptor Dynamics by Single-molecule Fluorescence Microscopy

Single-molecule microscopy is emerging as a powerful approach to analyze the behavior of signaling molecules, in particular concerning those aspect (e.g., kinetics, coexistence of different states and populations, transient interactions), which are typically hidden in ensemble measurements, such as those obtained with standard biochemical or microscopy methods. Thus, dynamic events, such as receptor-receptor interactions, can be followed in real time in a living cell with high spatiotemporal resolution. This protocol describes a method based on labeling with small and bright organic fluorophores and total internal reflection fluorescence (TIRF) microscopy to directly visualize single receptors on the surface of living cells. This approach allows one to precisely localize receptors, measure the size of receptor complexes, and capture dynamic events such as transient receptor-receptor interactions. The protocol provides a detailed description of how to perform a single-molecule experiment, including sample preparation, image acquisition and image analysis. As an example, the application of this method to analyze two G-protein-coupled receptors, i.e., &#946;2-adrenergic and &#947;-aminobutyric acid type B (GABAB) receptor, is reported. The protocol can be adapted to other membrane proteins and different cell models, transfection methods and labeling strategies.

This protocol describes how to use total internal reflection fluorescence microscopy to visualize and track single receptors on the surface of living cells and thereby analyze receptor lateral mobility, size of receptor complexes as well as to visualize transient receptor-receptor interactions. This protocol can be extended to other membrane proteins.

Single-molecule microscopy is emerging as a powerful approach to analyze the behavior of signaling molecules, in particular concerning those aspect (e.g., ...

Preparation of Mica Supported Lipid Bilayers for High Resolution Optical Microscopy Imaging

Supported lipid bilayers (SLBs) are widely used as a model for studying membrane properties (phase separation, clustering, dynamics) and its interaction with other compounds, such as drugs or peptides. However SLB characteristics differ depending on the support used. 
Commonly used techniques for SLB imaging and measurements are single molecule fluorescence microscopy, FCS and atomic force microscopy (AFM). Because most optical imaging studies are carried out on a glass support, while AFM requires an extremely flat surface (generally mica), results from these techniques cannot be compared directly, since the charge and smoothness properties of these materials strongly influence diffusion. Unfortunately, the high level of manual dexterity required for the cutting and gluing thin slices of mica to the glass slide presents a hurdle to routine use of mica for SLB preparation. Although this would be the method of choice, such prepared mica surfaces often end up being uneven (wavy) and difficult to image, especially with small working distance, high numerical aperture lenses. Here we present a simple and reproducible method for preparing thin, flat mica surfaces for lipid vesicle deposition and SLB preparation. Additionally, our custom made chamber requires only very small volumes of vesicles for SLB formation. The overall procedure results in the efficient, simple and inexpensive production of high quality lipid bilayer surfaces that are directly comparable to those used in AFM studies.

We present a method of preparing mica supported lipid bilayers for high resolution microscopy. Mica is transparent and flat on an atomic scale, but rarely used in imaging because of handling difficulties; our preparation results in even deposition of the mica sheet, and reduces the material used in bilayer preparation.

Supported lipid bilayers (SLBs) are widely used as a model for studying membrane properties (phase separation, clustering, dynamics) and its interaction ...

Nutrient Regulation by Continuous Feeding for Large-scale Expansion of Mammalian Cells in Spheroids

In this demonstration, spheroids formed from the &#946;-TC6 insulinoma cell line were cultured as a model of manufacturing a mammalian islet cell product to demonstrate how regulating nutrient levels can improve cell yields. In previous studies, bioreactors facilitated increased culture volumes over static cultures, but no increase in cell yields were observed. Limitations in key nutrients such as glucose, which were consumed between batch feedings, can lead to limitations in cell expansion. Large fluctuations in glucose levels were observed, despite the increase in glucose concentrations in the media. The use of continuous feeding systems eliminated fluctuations in glucose levels, and improved cell growth rates when compared with batch fed static and SSB culture methods. Additional increases in growth rates were observed by adjusting the feed rate based on calculated nutrient consumption, which allowed the maintenance of physiological glucose over three weeks in culture. This method can also be adapted for other cell types.

Nutrient regulation using continuous growth adjusted feeding improves growth rates of mammalian cell spheroids compared to intermittent batch feeding for cultures in stirred suspension bioreactors. This study demonstrates the methods required for establishing simple adjusted rate fed cultures.

In this demonstration, spheroids formed from the &#946;-TC6 insulinoma cell line were cultured as a model of manufacturing a mammalian islet cell product ...

Proper Positioning and Restraint of a Rat Hind Limb for Focused High Resolution Imaging of Bone Micro-architecture Using In Vivo Micro-computed Tomography

The use of in vivo micro-computed tomography (&#181;CT) is a powerful tool which involves the non-destructive imaging of internal structures at high resolutions in live animal models. This allows for repeated imaging of the same rodent over time. This feature not only reduces the total number of rodents required in an experimental design and thereby reduces the inter-subject variation that can arise, but also allows researchers to assess longitudinal or life-long responses to an intervention. To acquire high quality images that can be processed and analyzed to more accurately quantify outcomes of bone micro-architecture, users of in vivo &#181;CT scanners must properly anesthetize the rat, and position and restrain the hind limb. To do this, it is imperative that the rat be anesthetized to a level of complete relaxation, and that pedal reflexes are lost. These guidelines may be modified for each individual rat, as the rate of isoflurane metabolism can vary depending on strain and body size. Proper technique for in vivo &#181;CT image acquisition enables accurate and consistent measurement of bone micro-architecture within and across studies.

Proper Positioning and Restraint of a Rat Hind Limb for Focused High Resolution Imaging of Bone Micro-architecture Using In Vivo Micro-computed Tomography

This paper instructs users of in vivo micro-computed tomography (&#181;CT) scanners how to anesthetize, correctly position and restrain the hind limb of a rat for minimal movement during high-resolution imaging of the tibia. The result is high quality images that can be processed to accurately quantify bone micro-architecture.

The use of in vivo micro-computed tomography (&#181;CT) is a powerful tool which involves the non-destructive imaging of internal structures at high ...

High Resolution 3D Imaging of the Human Pancreas Neuro-insular Network

Using traditional histological methods, researchers are hampered in their ability to image whole tissues or organs in large-scale 3D. Histological sections are generally limited to &#60;20 &#181;m as formalin fixed paraffin section on glass slides or &#60;500 &#181;m for free-floating fixed sections. Therefore, extensive efforts are required for serial sectioning and large-scale image reconstruction methods to recreate 3D for samples &#62;500 &#181;m using traditional methods. In addition, light scatters from macromolecules within tissues, particularly lipids, prevents imaging to a depth &#62;150 &#181;m with most confocal microscopes. To reduce light scatter and to allow for deep tissue imaging using simple confocal microscopy, various optical clearing methods have been developed that are relevant for rodent and human tissue samples fixed by immersion. Several methods are related and use protein crosslinking with acrylamide and tissue clearing with sodium dodecyl sulfate (SDS). Other optical clearing techniques used various solvents though each modification had various advantages and disadvantages. Here, an optimized passive optical clearing method is described for studies of the human pancreas innervation and specifically for interrogation of the innervation of human islets.

Here, we present a protocol to image human pancreas sections in three dimensions (3D) using optimized passive clearing methods. This manuscript demonstrates these procedures for passive optical clearing followed by multiple immunofluorescence staining to identify key elements of the autonomic and sensory neural networks innervating human islets.

Using traditional histological methods, researchers are hampered in their ability to image whole tissues or organs in large-scale 3D. Histological ...

High-resolution Patterning Using Two Modes of Electrohydrodynamic Jet: Drop on Demand and Near-field Electrospinning

Electrohydrodynamic (EHD) jet printing has drawn attention in various fields because it can be used as a high-resolution and low-cost direct patterning tool. EHD printing uses a fluidic supplier to maintain the extruded meniscus by pushing the ink out of the nozzle tip. The electric field is then used to pull the meniscus down to the substrate to produce high-resolution patterns. Two modes of EHD printing have been used for fine patterning: continuous near-field electrospinning (NFES) and dot-based drop-on-demand (DOD) EHD printing. According to the printing modes, the requirements for the printing equipment and ink viscosity will differ. Even though two different modes can be implemented with a single EHD printer, the realization methods significantly differ in terms of ink, fluidic system, and driving voltage. Consequently, without a proper understanding of the jetting requirements and limitations, it is difficult to obtain the desired results. The purpose of this paper is to present a guideline so that inexperienced researchers can reduce the trial and error efforts to use the EHD jet for their specific research and development purposes. To demonstrate the fine-patterning implementation, we use Ag nanoparticle ink for the conductive patterning in the protocol. In addition, we also present the generalized printing guidelines that can be used for other types of ink for various fine-patterning applications.

Here, we present a protocol to produce high-resolution conductive patterns using electrohydrodynamic (EHD) jet printing. The protocol includes two modes of EHD jet printing: the continuous near-field electrospinning (NFES) and the dot-based drop-on-demand (DOD) EHD printing.

Electrohydrodynamic (EHD) jet printing has drawn attention in various fields because it can be used as a high-resolution and low-cost direct patterning ...

High-resolution Patterned Biofilm Deposition Using pDawn-Ag43

Spatial structure and patterning play an important role in bacterial biofilms. Here we demonstrate an accessible method for culturing E. coli biofilms into arbitrary spatial patterns at high spatial resolution. The technique uses a genetically encoded optogenetic construct&#8212;pDawn-Ag43&#8212;that couples biofilm formation in E. coli to optical stimulation by blue light. We detail the process for transforming E. coli with&#160;pDawn-Ag43, preparing the required optical set-up, and the protocol for culturing patterned biofilms using pDawn-Ag43 bacteria. Using this protocol, biofilms with a spatial resolution below 25 &#956;m can be patterned on various surfaces and environments, including enclosed chambers, without requiring microfabrication, clean-room facilities, or surface pretreatment. The technique is convenient and appropriate for use in applications that investigate the effect of biofilm structure, providing tunable control over biofilm patterning. More broadly, it also has potential applications in biomaterials, education, and bio-art.

We demonstrate a method for depositing Escherichia coli bacterial biofilms in arbitrary spatial patterns with a high resolution using optical stimulation of a genetically encoded surface-adhesion construct.

Spatial structure and patterning play an important role in bacterial biofilms. Here we demonstrate an accessible method for culturing E. coli biofilms ...

High-resolution Imaging of Nuclear Dynamics in Live Cells under Uniaxial Tensile Strain

Extracellular mechanical strain is known to elicit cell phenotypic responses and has physiological relevance in several tissue systems. To capture the effect of applied extracellular tensile strain on cell populations in vitro via biochemical assays, a device has previously been designed which can be fabricated simply and is small enough to fit inside tissue culture incubators, as well as on top of microscope stages. However, the previous design of the polydimethylsiloxane substratum did not allow high-resolution subcellular imaging via oil-immersion objectives. This work describes a redesigned geometry of the polydimethylsiloxane substratum and a customized imaging setup that together can facilitate high-resolution subcellular imaging of live cells while under applied strain. This substratum can be used with the same, earlier designed device and, hence, has the same advantages as listed above, in addition to allowing high-resolution optical imaging. The design of the polydimethylsiloxane substratum can be improved by incorporating a grid which will facilitate tracking the same cell before and after the application of strain. Representative results demonstrate high-resolution time-lapse imaging of fluorescently labeled nuclei within strained cells captured using the method described here. These nuclear dynamics data give insights into the mechanism by which applied tensile strain promotes differentiation of oligodendrocyte progenitor cells.&#160;

Using a previously designed device to apply mechanical strain to adherent cells, this paper describes a redesigned substratum geometry and a customized apparatus for high-resolution single-cell imaging of strained cells with a 100x oil immersion objective.

Extracellular mechanical strain is known to elicit cell phenotypic responses and has physiological relevance in several tissue systems. To capture the ...