Light sheet microscope tackles live coral imaging


Rebecca Pool

Tuesday, February 6, 2018 - 14:45
Image: Gentle light-sheet illumination captures coral [Nature Methods]
Researchers at the UK-based University of Essex have developed a new light sheet fluorescence microscope, called the Large Selective Plane Illuminator (L-SPI).
Developed in collaboration with instrument manufacturer, Cairn Research, the microscope is commercially available and offers long-term 3D imaging of small coral colonies without the observation light that stresses coral.
This is a major advance, since corals are highly photo-sensitive and easily damaged even by relatively low light levels.
Dr Philippe Laissue, from the School of Biological Sciences, developed the microscope during his Royal Society Industry Fellowship. 
As he says: “I was working with colleagues in the School’s Coral Reef Research Unit to get a better insight into coral bleaching and the development of reef-building corals."
"However, it soon became clear that if you use conventional microscopes, they tend to damage the observed coral, since they use much higher light intensities for the fluorescence," he adds. "This meant we could observe a coral sample only once, or only for a short period.
Left: Using a conventional microscope the polyp is fully retracted due to the intense light. Right: The polyp has fully emerged in the gentle illumination of a light-sheet fluorescence microscope developed at the University of Essex. [Nature Methods vol.14, 2017 Laissue]
Low light microscopy techniques have emerged over the last decade, revealing how easily many organisms and cells can be damaged by light.
It is crucial to avoid such damage to ensure that accurate data can be obtained from naturally behaving and developing specimens.
The L-SPI is designed to work with any macro- or microscope, single-mode fibre laser source and scientific camera.
It is equipped with a stage-mounted, fibre-coupled illuminator head that generates a wide, uniform lightsheet from two orthogonal directions, reducing shadowing without the need for sample rotation or image fusion.
"The microscope also offers great opportunities for looking at other specimens which are as sensitive to light as corals,” says Laissue. "This work... is technically important not just to corals, but to any other live samples."
Dr Laissue and colleagues have published a paper in Nature Methods which raises awareness of the issue of photo damage, an important consideration for any type of microscopy looking at live organisms.
Learn more here.
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