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Seeing the invisible; seeking a cure

MBL Senior Scientist Jennifer Morgan is investigating the causes of Parkinson’s disease, with an eye towards a cure. Her lab focuses on a clinical marker for the disease, aggregates of a protein called alpha-synuclein found in Lewy bodies. She studies how the aggregates form, how they cluster at nerve terminals (synapses), and whether they disrupt normal neural processing.

“But to study synapses, you have to be able to see them,” Morgan said in a presentation at the open house. Her lab recently showed that an excessive amount of alpha-synuclein disrupts normal synaptic trafficking. This could be a cause of Parkinson’s disease – a place to target a therapeutic drug.

“We now know what happens, but not why it happens,” she said. “We are really excited this new electron microscope (EM) is here so we can unwind this bowl of spaghetti that we see at the nerve terminals. “

Resolution is a measure of how close two objects can be before the microscope can’t distinguish them as separate. For routine biological material, the new EM is capable of 5 nm or better resolution – about 100,000^th the width of a human hair!

It also enables volume electron microscopy, which the journal Nature chose as one of “  Typically, electron microscopes give superior resolution only at the surface of the sample. To get a 3D image, the sample must be sectioned into very thin slices, each slice separately imaged, and then they are computationally recombined. The new Thermo Fisher Scientific EM, and others like it, vastly simplify this process.

Kerr thinks “we got the best of what we could out of one instrument,” as it can accomplish volume EM through two paths, each with its own strengths: array tomography (which doesn’t destroy the sample in the process) and focused ion beam imaging, which gives thinner slices and finer depth resolution, but is a destructive technique.

Multiple labels in one sample

A big advantage of the new light microscope, the Leica Stellaris 8 STED, is its white-light laser, according to Kerr and MBL Associate Director of Imaging Services Carsten Wolff. In fluorescence microscopy, the molecules the scientist wants to “see” are labeled with a fluorophore, such as green fluorescent protein (GFP), which gets excited at a particular wavelength. When the microscope’s laser hits the fluorophores, they absorb light of short wavelength and emit light of longer wavelength. Sensitive light detectors in the microscope can thus image the location of the fluorescently labeled molecules.

“We do a lot of multiplexing at MBL, where we put several different fluorophores in one sample,” Wolff said. (For example, four different kinds of proteins will have four different fluorescent labels.) “The Leica white-light laser – with a wavelength range from 450 nm to 790 nm – can produce up to eight different wavelengths simultaneously, so we can potentially have 10 different labels in one sample, or even more,” he said.

The Leica is also equipped for something amazing called fluorescence lifetime imaging microscopy (FLIM), “which continues to gain interest in biology; it used to be primarily used by biophysicists,” Wolff said. With FLIM, scientists can capture extremely small changes in the local environment around the molecules being imaged, such as the cell membrane. For example, a change in pH can be detected because it changes how fast or slow the fluorophores emit light, which the microscope measures. “We are already getting requests from the ǧ����Ƶ Physiology and Embryology courses to do FLIM,” said Wolff.

The new microscopes replace two instruments in MBL’s Central Microscopy Facility that had aged out of their service contracts. It will be wonderful to see the uses that imaginative scientists and students will find for them, for years to come.

“My strategy in selecting these – and I think everyone’s here – is to not only look at what we are doing today, but what we might want to do in the future,” Kerr said.

Patel and MBL Director of Research Anne Sylvester emphasized that these advanced instruments couldn’t be deployed without the technical expertise provided by the vendors. They thanked Leica representatives Manjot Deol, Haridas Pudavar and Louise Bertrand, and Thermo Fisher Scientific representative Geoff Perumal, for investing hours into training MBL scientists. Sylvester also acknowledged the guidance of Rosalee Maffitt, program manager for industry strategy and investments at the Massachusetts Life Sciences Center.

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ǧ����Ƶ (MBL) is dedicated to scientific discovery – exploring fundamental biology, understanding marine biodiversity and the environment, and informing the human condition through research and education. Founded in Woods Hole, Massachusetts in 1888, the ǧ����Ƶ is a private, nonprofit institution and an affiliate of the.