New article out: Mapping the axon initial segment components by mass spectrometry

First work of 2020 work is out! A collaboration with Matt Rasband’s lab in Nature Communications. This is a significant paper for the axon initial segment field. Matt’s lab used BioID of key AIS proteins for mapping AIS components. Dozens of new candidates for future studies!

Check all these new AIS proteins!

We performed super-resolution microscopy of several of the newly identified AIS components. IN particular, we showed that Mical3, a protein linking microtubules and actin, forms clusters along the AIS that are not periodically organized along the actin/spectrin scaffold.

Mical3 is present along the AIS but does not associate with the periodic actin/spectrin scaffold.

Our paper is out! The ultrastructure of the axonal actin rings revealed

Our work on the ultrastructure of the periodic actin/spectrin scaffold along axons is out in Nature Communications. It’s a collaboration with platinum-replica electro microscopy specialist Stephane Vassilopoulos from the Myologie Institute in Paris.

It’s easier to go there to read it (and it’s open access!)

In this work that was made available as a preprint back in May, we used ultrasonic unroofing to expose the submembrane cytoskeleton along axons in neuronal cultures. This allowed to observe it both by optical super-resolution microscopy and by platinum-replica electron microscopy, zooming down to individual proteins and actin filaments.

We could visualize for the first time by EM the periodic submembrane scaffold along axons, formed of actin rings connected by spectrin tetramers. Moreover, we discovered that actin rings are not made of small actin filaments bundled together as previously assumed, but by braids of long filaments that are likely to result in their stability and flexibility. Finally, we directly visualized elements of the periodic scaffold (actin, spectrins, myosin, ankyrin) using correlative super-resolution microscopy and platinum-replica electron microscopy.

Zooming from a cultured neuron to single ankyrins along the axon initial segment by correlative STORM/PREM

A press release from CNRS is available here in English and here in French for more details about this work. We are very happy to see it out!

Demoing the SoRa super-resolution spinning-disk microscope

For the last two weeks, we got to play with Nikon Instruments latest super-resolution spinning disk microscope that incorporates a Yokogawa SoRa head. It was installed in the INP NeuroCellular Imaging Service (NCIS) imaging facility.

The Nikon SoRa setup

We could make 3D-stacks and live-cell imaging movies of cells and neurons benefiting form the ~120 nm lateral resolution. See the how this compares to diffraction-limited imaging with this example from our samples:

Comparison between raw spinning disk, raw SoRa, and deconvolved SoRa images of a COS cell labeled for actin, microtubules, clathrin and DNA.

First edition of the INP day

Now that the Institute of Neurophysiopathology is settled as a whole on the Timone Campus of the AMU School of Medicine, we organized the first INP day at the Black Rock pub in Marseille. It was a big success with lots of fun and games! There were more scientific parts such as the 3-minute presentation by a PhD student of each team – Dominic did great for NeuroCyto.

The team leaders also recorded short “elevator pitches” that will be used to advertise to work of the INP teams – here’s a short behind-the-scenes video with Christophe explaining what we do:

video courtesy of Nicolas Fichera on LinkedIn

Visit to Cambridge

Christophe was invited to Cambridge by Kristian Franze and gave a seminar as part of the Adrian Seminar Series of the Department of Physiology, Development and Neuroscience. Thanks Kristian for the invitation and the glimpse to the splendid Cantabrigian life!

Saint John’s College in the morning

The next day, Christophe gave a seminar at the Chemical Engineering department, invited by Clemens Kaminski from the Laser Analytics Group. This was followed by a lively discussion with the group’s PhD students.

10-year anniversary of the ATIP-AVENIR program

On November 4th, a one-day symposium was organized at the College de France in Paris to celebrate the 10 years of the ATIP-AVENIR program, which funded and helped the creation of the NeuroCyto lab in 2017. We could hear about the history and evolution of the program from its creators and directors, as well as science stories from past awardees. Check more photos of the event here.

Christophe tries to hang a poster summarizing what the lab is about…
Success for the images-as-business cards part of the poster!