New Microscope Watches Cells in 3D 50
Jamie found a story about a new 3D Microscope which creates 3D videos of cells in action. Traditionally scientists have had to choose between high resolution and animation, so no doubt this device will cure the common cold.
Bad summary... (Score:5, Informative)
Re:Death by light (Score:5, Informative)
The article says that they are actually imaging the refracted light. Since this technique doesn't require any amount of sample absorption at all, they can use a minimally absorbing wavelength, thereby keeping sample damage to an absolute minimum. In fact since they are measuring refracted light, the technique works best at wavelengths where absorption is as low as possible (but refractive index contrast is as high as possible).
From the description, it doesn't sound like the illumination would be much more intense than what a normal microscope generates. Most cells don't experience significant photo-damage under such illumination conditions.
Some current imaging systems use a raster-scanned focused-laser spot to generate the images. By using high-quality detectors the light-levels can be kept low enough that cell damage is prevented. Thus the technique from the article probably induces less cell damage than currently used techniques. Not to mention that the fact that you don't have to stain or modify the cells eliminates the toxicity (or perturbing effect) or those staining agents.
Re:Death by light (Score:4, Informative)
Re:Death by light (Score:5, Informative)
"Cellular Organization and Substructure Measured Using Angle-Resolved Low-Coherence Interferometry [biophysj.org]", Wax A, Yang C, Backman V, Badizadegan K, Boone C, Dasari RR, Feld MS. Biophysical Journal 82: 2256-2264 (2002).
In the experimental section of that article they say: This appears to be one of their more recent publications:
"Quantitative phase imaging of live cells using fast Fourier phase microscopy [osa.org]", Niyom Lue, Wonshik Choi, Gabriel Popescu, Takahiro Ikeda, Ramachandra R. Dasari, Kamran Badizadegan, and Michael S. Feld. Applied Optics, Vol. 46, Issue 10, pp. 1836-1842.
In that paper they say: The illumination sources are not very intense, but are powerful enough to cause cell damage if they were highly focused. From looking over the papers it doesn't seem that this is the case. For what it's worth, the papers do not mention cell damage as being a concern.
Overall the technique seems to have serious promise. It essentially involves doing laser interferometry on the sample at multiple angles, and reconstructing the 3D image. As they mention in their papers, it has the advantage of interfacing with conventional confocal microscope designs. Thus it could be added as an option on existing setups. It appears to have some exacting requirements (like all holography/interferometry it will be sensitive to vibrations, etc.), but overall seems like the type of thing that could be rapidly built into existing labs and commercial instruments.
Re:Death by light (Score:2, Informative)
Until June, I had been working in a live-cell imaging laboratory for nearly four years. There's a whole list of criteria that will cell proliferation while being grown on a microscope. My lab had (before I arrived) already proven they could grow cells on a microscope stage that would match cells grown in an incubator (ie, number of mitotic events). These like this are important.
A few people have mentioned bits about imaging and I thought I'd kind of list the important ones:
'Normal' brightfield microscopes are the kind that you'll find in a high school classroom. They work because the sample absorbs light. When they talk about fixing and staining cells, you can use these. Usually cells are transparent and won't attenuate light as it passes through the cell.
Confocal works by exciting a fluorophor with a laser and measuring the emitted photons. Its neat. But you're pointing a laser at a cell.
DIC, AFM and others work on varied principles. AFM is atomic force. They basically poke a cell and measure how it pushes back. But you're poking a cell. DIC are light based but as far as I have seen not extremely popular in the field of live cell imaging for one reason or another.
Phase-Contrast I left till last as its really the only microscope that can be used for live-cell imaging. It works by measuring not how much the light is attenutated, but how much its slowed as it passes through the cell. Basically, a small fraction of light is slowed and difracted as it passes through the sample. The light that passes through unaffected is attenuated after the sample so it and the two groups have approximately the same intensity. Then normal interference will give an image on the detector.
As usual for science articles, it got most of the details wrong. We've had phase-contrast microscopes for over 50 years now. Zernike got the Nobel Prize for inventing them in 1953 http://nobelprize.org/educational_games/physics/mi croscopes/phase/index.html [nobelprize.org] We can use these to measure living cells. We could do drug screening. Nothing the article said was really new and frankly it was rather irritating.
What is exciting though is the fact that this might allow the machine vision guys to be able to reliably segment live-cell image data. Currently this is a problem with no *acceptable* solution. [By acceptable I mean to say, something that has an accuracy over 90-95% for any cell line I give it as well as not using anything like a nuclear stain] Once we get this level of segmentation there is an unlimited number of things we can do:
Re:Press Release Science (Score:3, Informative)
As to how difficult it is to get working... The papers indicate that it can be fitted onto a conventional confocal microscope. However because it is an interferometry technique, things like vibrations must be minimized. So it's probably a bit finnicky, but I any research lab with experience in optics could build one if they really wanted to. The technique uses off-the-shelf technology, so commercial instruments (probably sold as add-ons to existing microscopes) could easily be built. I'm not an expert in the field, so I can't predict whether there would be a strong demand for such an instrument.
(Note: I've used various microscopies in my research, but not on biological samples, so please correct any mistakes I've made in that regard.)
3D movies of living cells (Score:1, Informative)
Re:Actually buy one (Score:2, Informative)