Researchers at the Howard Hughes Medical Institute have pioneered an imaging technique which renders living cells in 3D via a system of ‘light sheets’ according to reports in Nature Methods.
The light sheets consist of a technique called plane illumination, in which light is shone in a tight beam horizontally across a microscope slide, rather than the slide being illuminated from above or below. The microscope’s image is comprised of the light that reflects from the cells upwards. The idea is that the beam is illuminating only the plane on which the microscope is focused.
Each sliver of light provides only a tiny fragment of detail, but by rapid scanning and pulsing of the light beam, Dr Eric Betzig and his team at the HHMI are able to produce a composite 2D image of a living cell – and by adjusting the beam’s vertical alignment fractionally, a 3D image is composed from 200 light sheets a second.
The technique also enables the researchers to capture cellular process in action as the living cells divide and reproduce. This has not previously been possible as the light from traditional microscopes can itself damage and kill living cells. Bessel beams – which have also been keys to the recent development of a so-called tractor beam based on lasers – are used to generate the tiny slivers of information.
High-speed isotropic 3D imaging of living cells will be immensely useful to cellular biologists, particularly as the technique is so non-invasive. The combination of the Bessel beam with structured illumination is an elegant solution – there are methods of gaining higher resolution cell images, but the three dimensional aspect, and specifically the opportunity to observe cellular processes in three dimensions is an incredibly exciting development, superior to many aspects of confocal and wide-field microscopy.
Reporting the discovery, the BBC quoted Dr Betzig as saying:
“You can get a lot of information looking at fixed, dead cells – high-resolution information – but you’d still like to be able to see dynamics… there’s a lot you can learn from actually watching things wiggle around.”
Video footage of the images generated using this 3D microscope are undeniably impressive and as well as the implications for cellular research, the technology could go some way to helping non-scientific minds gain a more solid understanding of the cells which make up all living things.
Original report in Nature Methods: http://www.nature.com/nmeth/index.html (requires subscription)
BBC report: http://www.bbc.co.uk/news/science-environment-12649622