New research microscope reveals the inner light of cells

Monday, 6 August 2001

Zoologists, anatomists, physiologists and more have all faced the same research dilemma; investigation can destroy what is being examined, or change it so much that it is no longer the thing that they want to examine.

Microscopy has been one of the most powerful tools in modern science; the scientist seated at a microscope is a symbol of modern research, but even microscopy takes a toll of its subjects.

Traditionally, tissues have been killed, then frozen or embedded in blocks of paraffin, and sliced much thinner than paper for microscopic inspection. Such treatment was necessary to allow light to pass through the tissue, as it does through a stained glass window, to reveal its cellular details. Electron microscopy can be even more severe.

A new multi-photon microscope at the Waite Campus offers South Australian researchers a new, non-invasive way to examine living tissue and intact cells without having to destroy them.

"The multi-photon microscope differs from this sort of microscope because it allows you to produce images inside intact cells without having to destroy the cells themselves," said Dr. Meredith Wallwork, Manager of the Confocal Facility at the Waite Campus, where the new microscope will be located.

The multi-photon microscope is a very specialised fluorescence microscope, comprising a laser and conventional fluorescence microscope all operated by computer. The laser produces rapid pulses of long wavelength red light, creating images of biological material by showing up those structures inside cells that fluoresce under light.

This fluorescence may be inherent in the material itself, due to its chemical composition, or the material may be stained with one or more fluorescent dyes to show up particular structures or compounds.

The fluorescent images give information about particular structures inside living cells, or of reactions going on within the cells, without damaging or killing them.

"There is evidence that living cells can be observed with the multi-photon microscope for hours, as opposed to minutes, as is the case with more conventional fluorescence microscopy," said Dr Wallwork.

"In simple terms, the multi-photon can be thought of as a CAT scanner for cells," said Dr Wallwork. "It is designed to generate a series of optical sections through a bulky sample and then with powerful computer processing, to reconstruct these sections into a complete 3D image of the sample."

"Exposure of the whole sample to the laser beam is reduced in this microscope, so there is less loss of fluorescence as well as less likelihood of photobleaching, and therefore damage to the sample," said Dr Wallwork. "Clear images are visible to greater depths."

The multi-photon microscope was purchased through a successful ARC grant application made by Adelaide University, Flinders University, The University of South Australia, the CSIRO and Institute of Medical and Veterinary Sciences in cooperation.

It is used by researchers from all these organisations, and has a wide range of applications in examining diverse plant and animal tissue, from individual cell cultures to intact tissues such as embryos.

"There are likely to be some very useful applications for research and development organisations in the private sector as well, especially in new technology areas," said Dr Wallwork.. "It will help researchers in South Australia, and assist cooperation between our collaborators," she said. "We are encouraging people to make use of this new and exciting technology for basic research."

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