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Jana Kroll

@janakroll.bsky.social

190 followers 240 following 20 posts

Postdoc at MDC Berlin cryo-electron tomography, neuronal synaptic transmission, optogenetics

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Jana Kroll @janakroll.bsky.social · Feb 12

Excited to share our new preprint "Dynamic nanoscale architecture of synaptic vesicle fusion in mouse hippocampal neurons" www.biorxiv.org/content/10.1...

We combine optogenetic stimulation of neurons with in situ cryo-ET to characterize membrane dynamics during synaptic vesicle fusion ❄️🔬⏱️

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Jana Kroll @janakroll.bsky.social · 7d

Thank you so much! 😊

Reposted by Jana Kroll

Misha Kudryashev @mishakudryashev.bsky.social · 7d

Group Leader in Biomedical Engineering at the @mdc-berlin.bsky.social in Berlin.

It's a broad call for whoever is doing exciting Bioengineering, please apply or share. We have a great institute with amazing colleagues and core facilities,highly recommend

application.mdc-berlin.de/site/index.p...

MDC Berlin - Online Application System

application.mdc-berlin.de

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Reposted by Jana Kroll

Misha Kudryashev @mishakudryashev.bsky.social · Aug 4

Postdoc program at the MDC in Berlin, @mdc-berlin.bsky.social : take a look 👇👇

For this call, collaborative projects between two groups will be funded. Take a look at the call and the groups and drop me an email if interested. Share with colleagues too!

www.mdc-berlin.de/postdocs#t-g...

www.mdc-berlin.de

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Reposted by Jana Kroll

Max Delbrück Center @mdc-berlin.bsky.social · Jul 17

🏆 Images from #mdcBerlin received top honors in the @helmholtzimaging.bsky.social “Best Scientific Image Contest”!

Jury Award for @janakroll.bsky.social, Daumke Lab
Public Choice Award for Dr. Rafael Deliz Aguirre, @coscialab.bsky.social

Full details: www.mdc-berlin.de/news/news/tw...

Excitation
This image captures a mouse hippocampal neuron surrounded by numerous extensions that connect to other neurons via synapses. The cultured cell is equipped with a yellow fluorescent sensor for the neurotransmitter glutamate, which is normally used at room temperature. In this case, the image was captured at -170 °C using CFcryo-EM (Core Facility for Cryo–Electron Microscopy).
Image: Dr. Jana Kroll, Daumke Lab

Starfish Puts Motion Back in the Ocean
This image shows starfish embryos that are only a few days old, using their tiny tentacles to create currents that visually and mathematically reflect the Earth’s magnetic field. The living embryo on the left of the image – unlike the immobile, dead embryo on the right – is actively shaping its fluid environment. The image was captured using bright-field microscopy and fluorescent particles.
Image: Dr. Rafael Deliz Aguirre, Coscia Lab

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Reposted by Jana Kroll

Misha Kudryashev @mishakudryashev.bsky.social · Jun 8

We have a preprint for you

EHD2 forms rings on caveolae necks, in contrast to most EHDs forming helices. We determined its structure on membranes and show that N-term acts as a spacer

By Elena, Vasya @vasiliimikirtumov.bsky.social, Jeff &Oli Daumke www.biorxiv.org/content/10.1...

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Jana Kroll @janakroll.bsky.social · May 27

What an inspiring morning at the CatCat Symposium! Thank you so much for inviting me @gallegolab.bsky.social and @felixmendu.bsky.social, it's been a pleasure visiting you in Barcelona 😊

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Jana Kroll @janakroll.bsky.social · May 13

In the left image, I see a queen with a crown🫅 But I guess that's not what you meant? 😅

Jana Kroll @janakroll.bsky.social · May 12

So many amazing images! 🤩 🤩🤩

Please make sure to vote, mine is also in the list 😎

Helmholtz Imaging @helmholtzimaging.bsky.social · May 12

🎉 Public Voting Now OPEN – #HelmholtzImaging Best Scientific Image Contest 2025

Choose your favorite(s) & cast your vote by May 30 👉 bit.ly/BSIC2025-Public-Voting

The award recipients will be announced at our conference on June 26.

#HIBestImage25 #HIConference25
@www.helmholtz.de

Reposted by Jana Kroll

Misha Kudryashev @mishakudryashev.bsky.social · Apr 8

A broad call for a PhD researcher/ postdoc in our group at the MDC in Berlin. An ideal PhD student - a computational scientist, a postdoc - a structural biologist, but feel free to re-convince me!

We extended the deadline for after Easter, Apr 24th. Apply here www.mdc-berlin.de/career/jobs/...

Scientific Researcher – Method Developments for In situ Structural Biology (F/M/D)

The Max Delbrück Center for Molecular Medicine in the Helmholtz Association aims to transform tomorrow’s medicine through our discoveries of today. At locations in Berlin-Buch, Berlin-Mitte, Heidelber...

www.mdc-berlin.de

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Reposted by Jana Kroll

Misha Kudryashev @mishakudryashev.bsky.social · Mar 28

We are looking for a PhD student/Postdoc to develop methods of cryo-ET and/or study the structure and function of membrane proteins. Great team at the MDC in Berlin.

It's a broad call, please apply and share!
jobrxiv.org/job/max-delb...

PhD /Postdoc in In Situ Structural Biology by Cryo-ET

Post a job in 3min, or find thousands of job offers like this one at jobRxiv!

jobrxiv.org

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Reposted by Jana Kroll

Felix Campelo @felixmendu.bsky.social · Mar 14

Together with @gallegolab.bsky.social we are organizing the next CATCAT morning on "Dynamics in biology, from molecules to tissues", with an amazing lineup of local and international speakers. If in Barcelona on May 26th, don't miss it, it's free! www.catcat-celltissuebiology.cat/event/9th-ca...

Program of the 9th CATCAT morning on "Dynamics in biology, from molecules to tissues", May 26th 2025

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Jana Kroll @janakroll.bsky.social · Feb 21

Cryo-confocal microscopy of a neuron expressing the glutamate sensor iGluSnFR 🥶 The neuron was optogenetically stimulated and subsequently plunge-frozen to preserve the high fluorescence intensity indicating neurotransmitter release. #FluorescenceFriday

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Jana Kroll @janakroll.bsky.social · Feb 16

Thank you!

Jana Kroll @janakroll.bsky.social · Feb 15

The video shows more than 50 snapshots of vesicle fusion events in synapses, sorted by fusion progression 😎

Jana Kroll @janakroll.bsky.social · Feb 14

Thank you! 😊

Jana Kroll @janakroll.bsky.social · Feb 13

Thank you!

Jana Kroll @janakroll.bsky.social · Feb 13

Thank you!

Jana Kroll @janakroll.bsky.social · Feb 12

... but also between vesicles and cytoskeletal fibers likely resembling actin.

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Jana Kroll @janakroll.bsky.social · Feb 12

We did not only observe filamentous connectors at vesicles but also between vesicles and fusion events....

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Jana Kroll @janakroll.bsky.social · Feb 12

We further quantified distributions and tethering of synaptic vesicles at the active zone. Tether numbers closely correlated to the distance between vesicle and membrane, but not to their respective fusion readiness.

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Jana Kroll @janakroll.bsky.social · Feb 12

Overall, we analyzed more than 400 tomograms of synapses and identified more than 50 vesicle fusion intermediates. We classified and morphometrically characterized them.

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Jana Kroll @janakroll.bsky.social · Feb 12

Beyond that, we were able to correlate the cryo-fluorescent signal of iGluSnFR3 with a tomogram of a neuronal synapse. The arrowhead points to a putative vesicle fusion event.

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Jana Kroll @janakroll.bsky.social · Feb 12

We confirmed successful stimulation via cryo-confocal microscopy of the glutamate sensor iGluSnFR3. With this experiment, we also proved that fast fluorescent biosensors can be used under cryogenic conditions.

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Jana Kroll @janakroll.bsky.social · Feb 12

We developed a workflow for time-resolved in situ cryo-ET by coupling optogenetics with subsequent plunge freezing of neurons. Our setup allowed us to stimulate neurons only a few milliseconds before cryofixation.

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Jana Kroll @janakroll.bsky.social · Feb 12

First and foremost, thank you @icecoldsynapse.bsky.social, @mohsensadeghi.bsky.social, @mishakudryashev.bsky.social, Christoph, Lia, Gosia, Thiemo, Magdalena and Christian for your contributions!

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