Biology moves into the third dimension, may help observe how a brain develops and viruses attack
Researchers at NIH have developed two new microscopes, both the first of their kind. The first captures small, fast moving organisms at an unprecedented rate and the second displays large cell samples in three dimensions while decreasing the amount of harmful light exposure to the cells. Both microscopes surpass in clarity any other currently on the market.
“It’s always helpful to look at smaller and smaller things,” said Hari Shroff, Ph.D., at NIH’s National Institute of Biomedical Imaging and Bioengineering (NIBIB) lab chief of NIBIB’s section on High Resolution Optical Imaging (HROI.) “Looking at a fixed cell at high resolution can tell you where different parts of the cell are at any given moment; but because much of biology depends on the movement of very small proteins finding each other and interacting, we really needed to look at how things move in a live cell.”
The problem is that the higher the resolution, the harder it is to eliminate the blur from both light diffraction (the glow that sometimes occurs as light bends around objects) and the motion going on inside the live cell. Traditional linear structured illumination microscopy (SIM) cannot maintain the high resolution desired by researchers when the sample is moving quickly.
If a photographer wants to take a better photograph, he can either buy a camera with a better lens and higher pixels or he can modify the picture after it’s taken, using Photoshop. The principle is similar in microscopy. Instead of approaching the problem by creating better imaging software that helps to increase the resolution after the fact, as most high resolution microscopes do, Shroff and his lab developed a microscope with better lenses and mirrors so that the higher resolution is captured in the original image.
“What we’ve essentially done is eliminate the need for extensive computer processing by creating a better microscope at every stage of data gathering,” said Shroff. “Before, we relied on computer software and algorithms to do things like sort through hundreds of images, eliminate out of focus light, and combine the individual images together. Now, we can do most of that optically with the microscope itself.” This means that researchers can skip the time-consuming steps in which computers process the massive amounts of data normally required for such high resolution imaging. Now they will be able to see the images instantly instead of waiting hours or sometimes days, and the data itself takes about 1% of the hard drive space as that produced by previous microscopes.
In order to combat this problem, Shroff and NIBIB staff scientist Yicong, Wu, Ph.D., developed a dual-view SPIM (diSPIM) microscope with two separate detection cameras. The cameras are set at a 90 degree angle to capture perpendicular views of the sample. This perpendicular view results in undistorted 3-dimensional images, and since only two views are acquired, the microscope can still capture events at very high speed. Additionally, with relatively simple modifications, traditional single camera SPIM microscopes can be converted into the dual-camera diSPIM. The real challenge in developing this technology was to find a way to combine the two disparate images from the two cameras, which required the creation of a new post-processing software algorithm.
The increased speed at which the new dual microscope can image the cells allows for clearer images of even very fast moving viruses. Being able to see how a virus enters a cell, and once it’s in, how it moves around, could go a long way towards scientists’ understanding of how infections occur and potentially how to fight them more effectively. In the same way, observing the migration of cancer cells in a 3-D environment could unlock information on how cancer grows, finds nutrients, and spreads.
The Shroff lab has already begun multiple collaborations with biological labs both inside the NIH as well as external institutions, including Yale, Sloan Kettering, and the University of Connecticut Health Center.
1. Wu, Yicong, Peter Wawrzusin, Justin Senseney, Robert S. Fischer, Ryan Christensen, Anthony Santella, Andrew G. York, Peter W. Winter, Clare M. Waterman, Zhirong Bao, Daniel A. Colón-Ramos, Matthew Mcauliffe, and Hari Shroff. "Spatially Isotropic Four-dimensional Imaging with Dual-view Plane Illumination Microscopy." Nat Biotechnol Nature Biotechnology 31.11 (2013): 1032-038. Web.
2. York, Andrew G., Panagiotis Chandris, Damian Dalle Nogare, Jeffrey Head, Peter Wawrzusin, Robert S. Fischer, Ajay Chitnis, and Hari Shroff. "Instant Super-resolution Imaging in Live Cells and Embryos via Analog Image Processing." Nature Methods Nat Meth 10.11 (2013): 1122-126. Web.