Jana Kroll

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Our lab opens 2 PhD positions to investigate fungi's evolution: #Barcelona

Wet lab in Biochemistry/Structural Biology of cryo-tolerant fungi
www.upf.edu/documents/d/...

Computational in Physical Chemistry of cellular processes under extrem environments
www.upf.edu/documents/d/...

Imaging spotlight: visualising synaptic vesicle fusion by cryo-ET - FocalPlane Imaging spotlight: visualising synaptic vesicle fusion by cryo-ET - News

🔬🔦 Imaging spotlight on FocalPlane
@janakroll.bsky.social and colleagues highlight their research visualising synaptic vesicle fusion using cryo-ET combined with plunge freezing and optogenetics.

focalplane.biologists.com/2026/01/21/i...

❄️ With all the snow outside, I felt like sharing a cryo tomogram:

A neuronal synapse, captured by cryo-ET at the moment a neurotransmitter-filled vesicle fuses at the active zone.

Fusion was triggered optogenetically and arrested by plunge freezing.

More details: www.nature.com/articles/s41...

Der Moment, in dem eine Nervenzelle ihre Neurotransmitter in den synaptischen Spalt ausschüttet, ist extrem kurz. Berliner Forschenden @bihatcharite.bsky.social @mdc-berlin.bsky.social konnten ihn mikroskopisch einfangen.
doi.org/10.1038/s414...

Bild: © Charité/Max Delbrück Center, Jana Kroll

Dynamic nanoscale architecture of synaptic vesicle fusion in mouse hippocampal neurons - Nature Communications Synaptic vesicle fusion is essential for neuronal communication, yet its nanoscale sequence has not been directly confirmed. Here, the authors use timed in situ cryo-electron tomography to visualize t...

A breathtaking glimpse into the #brain at work: NeuroCure researchers & colleagues @janakroll.bsky.social captured #synapses in action - revealing how #neurotransmitters are released in milliseconds 🧠 Published in NatureCommunications @Charite @mdc-berlin.bsky.social
www.nature.com/articles/s41...

It's been a fantastic experience to publish our work in @natcomms.nature.com and I sincerely thank the reviewers of our paper for their constructive and helpful comments! (8/8)

I deeply thank all co-authors for their constant support over the past years: @uljakravcenko.bsky.social, @mohsensadeghi.bsky.social, Christoph Diebolder, Malgorzata Lubas, Lia Ivanov, Thiemo Sprink, Magdalena Schacherl, @mishakudryashev.bsky.social and Christian Rosenmund. (7/8)

Intriguingly, we observed filamentous connectors between the majority of fusing vesicles and at least one more adjacent vesicle. We suggest that these interconnectors physically couple vesicle fusion and direct vesicle resupply required for release site refilling. (6/8)

Our morphometric and computational analyses revealed that synaptic vesicle fusion is likely initiated via stalk formation, whereby vesicle and cell membrane form a tip-like connection. We did not find evidence for tight docking or strong membrane bending prior to fusion. (5/8)

In these stimulated synapses, we identified more than 50 synaptic vesicle fusion intermediates and characterized them morphometrically at nanoscale resolution and under near-native conditions. (4/8)

We confirmed successful optogenetic stimulation of synapses directly via cryo-confocal microscopy of the glutamate sensor iGluSnFR3. Neurotransmitters, released during exocytosis, induced an increase in fluorescence intensity that was preserved under cryo conditions. (3/8)

We established a timed in situ cryo-electron tomography workflow to capture the complete sequence of synaptic vesicle fusion in optogenetically stimulated mouse neurons. Using a modified plunge freezer, the "Voptobot", we stimulated neurons only 2-3 milliseconds before cryofixation. (2/8)

❄️🔬⏱️
I am excited to share that our study „Dynamic nanoscale architecture of synaptic vesicle fusion in mouse hippocampal neurons” has been published in Nature Communications www.nature.com/articles/s41...

👇 Short summary of our key findings (1/8)

💥I am excited to present our first research paper from the lab about caveolae lipid trafficking 🎉 Led by my fantastic PhD candidate @estherocket.bsky.social

Here we looked into caveolae mediated dietary lipid uptake and how this process is mechanistically facilitated 👇 1/n

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

We got a large Helmholtz Bioengineering grant with Oliver Daumke, Artur Yakimovich, Alina Bazarova, and Dietrich Ruess to use protein design to target cancer.

Five open postdoctoral positions in Generative AI & Protein Engineering. Share & apply!

jobrxiv.org/job/max-delb...

Thank you so much! 😊

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...

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...

scientific image

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

scientific image

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

🏆 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...

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...

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 😊

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

So many amazing images! 🤩 🤩🤩

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

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/...

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!

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...

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

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...

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

Thank you!

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

Thank you! 😊