Insights into Parkinson's balance problems

In PD, disorganized sensorimotor signals cause muscles in the limbs to contract, such that both a muscle promoting a motion and its antagonist muscle are Read more

Cajoling brain cells to dance

“Flicker” treatment is a striking non-pharmaceutical approach aimed at slowing or reversing Alzheimer’s disease. It represents a reversal of EEG: not only recording brain waves, but reaching into the brain and cajoling cells to dance. One neuroscientist commentator called the process "almost too fantastic to believe." With flashing lights and buzzing sounds, researchers think they can get immune cells in the brain to gobble up more amyloid plaques, the characteristic clumps of protein seen in Read more

James Zheng

Fly model of repetitive head trauma speeds up time

Tap tap tap ka-CHUNK! That was the sound of fruit flies being given concussions in an Emory laboratory recently.

Emory MD/PhD student Joe Behnke, working with neuroscientist James Zheng, has developed a model for studying repetitive head trauma in the fruit fly Drosophila melanogaster – analogous to CTE (chronic traumatic encephalopathy) in humans. The results were published in Scientific Reports.

CTE is a term for neurodegeneration linked to repeated concussions or blows to the head, which has been observed in athletes and military veterans. Head trauma has also been linked to other neurodegenerative diseases such as Alzheimer’s, Parkinson’s and ALS (amyotrophic lateral sclerosis).

What’s critical about using fruit flies is that it speeds up time. It can take years or decades for CTE or other neurodegenerative conditions to appear in humans, but Behnke and Zheng can experiment with a mutant fly strain or other interventions in a few weeks. They describe their model as a platform for future studies, in which they can unleash all of the genetic tools fruit flies have to offer.

MD/PhD student Joe Behnke with the apparatus for delivering Drosophila head injuries

To begin with, Behnke worked out a system for giving flies controlled blows to the head. He says that it exploits the climbing instinct flies have when startled, called negative geotaxis. When he taps a vial with flies in it three times, they reorient themselves and begin climbing up. Then a stronger blow, delivered in a crash test-like apparatus, gives flies the desired head injury. Previous models in flies hadn’t really focused on the head, but gave them injuries all over their bodies.

Already, Behnke and Zheng have been able to demonstrate that female fruit flies are more vulnerable to repeated head injuries than males. Repeated head injury results in locomotor deficits and shortened lifespan and accelerates age-related degeneration.

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Posted on by Quinn Eastman in Neuro Leave a comment

Seeing the nuts and bolts of neurons

Cool photo alert! James Zheng’s lab at Emory is uncommonly good at making photos and movies showing how neurons remodel themselves. They recently published a paper in Journal of Cell Biology showing how dendritic spines, which are small protrusions on neurons, contain concentrated pools of G-actin.

Actin, the main component of cells’ internal skeletons, is a small sturdy protein that can form long strings or filaments. It comes in two forms: F-actin (filamentous) or G-actin (globular). It is not an exaggeration to call F- and G-actin neurons’ “nuts and bolts.”

Think of actin monomers like Lego bricks. They can lock together in regular structures, or they can slosh around in a jumble. If the cell wants to build something, it needs to grab some of that slosh (G-actin) and turn them into filaments. Remodeling involves breaking down the filaments.

At Lab Land’s request, postdoc and lead author Wenliang Lei picked out his favorite photos of neurons, which show F-actin in red and G-actin in green. Zheng’s lab has developed probes that specifically label the F- and G- forms. Where both forms are present, such as in the dendritic spines, an orange or yellow color appears.

Why care about actin and dendritic spines?

*The Journal of Cell Biology paper identified the protein profilin as stabilizing neurons’ pool of G-actin. Profilin is mutated in some cases of ALS (amyotrophic lateral sclerosis), although exactly how the mutations affect actin dynamics is now under investigation.

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Posted on by Quinn Eastman in Neuro Leave a comment

Six beautiful images — choose your favorites

WoodruffMatthew1

Matthew Woodruff — Bali Pulendran lab

ImageJ=1.48g unit=micron

Kenneth Myers — James Zheng lab

Joshua_Strauss_OPE_Image

Joshua Strauss — Elizabeth Wright lab

AndersonJoAnna

JoAnna Anderson — Francisco Alvarez lab

AlexTamas

Alexey Tamas — Charles Searles lab

Emory’s Office of Postdoctoral Education is holding a Best Image contest. The deadline to vote is this Thursday, April 30. You can look at these beautiful images (and guess exactly what they are, based on what lab they come from), but to VOTE, you need to go to the OPE site.

This is part of the run up to their Postdoctoral Research Symposium at the end of May.

(Hat tip to Ashley Freeman in Dept of Medicine!)

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Posted on by Quinn Eastman in Uncategorized Leave a comment

Visualizing retrograde flow

This month’s intriguing image is a set of videos produced by cell biologist James Zheng’s laboratory. Looking at this video of a cell can be mesmerizing. The edges of the cell appear to be flowing inward, like a waterfall. Zheng explains that this is a phenomenon called “actin retrograde flow.”

Actin is a very abundant protein found in animals, plants and fungi that forms filaments, making up the cell’s internal skeleton. What we are seeing with retrograde flow is that molecules of actin are being added to one end of the filaments while coming loose from the other end.Actin

Zheng’s laboratory is studying a protein called cofilin, which disassembles actin filaments. Using a technique called CALI (chromophore-assisted laser inactivation) the scientists http://www.troakley.com/ used a laser to blast cofilin, inactivating it. This is why, partway through the loop, after the word CALI appears, the flow slows down. Postdoctoral fellow Eric Vitriol is the lead author on a paper in Molecular Biology of the Cell that includes these videos.

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Posted on by Quinn Eastman in Uncategorized Leave a comment