Jaakko Lehtimäki

My biggest thanks to Caren and @nordenlab.bsky.social “so long and thanks for all the zebrafish🐟”, for intensive but very rewarding 3.5 years. Also, thanks to all the collaborators for making this happen! Looking forward for more zebrafish expansion microscopy with @mariodelr.bsky.social

A final milestone of my Lisbon-era☀️ Such an interesting type of migration and I just love all those dynamic protrusions❤️.
Compared to my bioRxiv thread bsky.app/profile/jale..., we have here more data especially on the attractive neurturin-Gfrα axis.

CELL MIGRATION LAB We study cell migration in health and disease

🚨 We are hiring TWO postdocs to join the Cell Migration Lab (cellmig.org) 🇫🇮 as part of the new Centre of Excellence in Immune–Endothelial Interfaces (IMMENs).
Join us to decode immune regulation & develop next-gen imaging tools! 🧪🔬
Details in thread 🧵👇
#ScienceSky #Postdoc #AcademicJobs Please RT🫶

Laboratory Engineer (Senior), in Advanced Imaging, 1.5.2026-31.12.2028

🚨 Job Alert! 🚨

We have an opening at our Microscopy Core Facility in Turku 🇫🇮.
If you love imaging 🔬 and helping scientists succeed, we want you! 👇

abo.rekrytointi.com/paikat/index...

#Microscopy #ScienceJobs #CoreFacility #Imaging
@turkubioscience.bsky.social

Interested in Zebrafish brain imaging? We released a 3D printed mold that's is super helpful for us. Check it out

Customizable FDM-based zebrafish embryo mold for live imaging
www.biorxiv.org/content/10.1...

Work by Marcela and Jaakko in the lab

Zebrafish use spectral information to suppress the visual background Vertebrate eyes first evolved in water, where spectral content rapidly fades with distance. Zebrafish exploit this loss by antagonizing cone signals to suppress the background, pointing to distance estimation—rather than color—as an ancestral cone function.

Now online! Zebrafish use spectral information to suppress the visual background

Mind-boggling. Remember seeing older papers on playing music to cultured cell lines. Would love to see the reviewer responses on this one.

Eric Peterman @errricpeterman.bsky.social, Jeffrey Rasmussen @jraslab.bsky.social @uwbiology.bsky.social & colleagues discover that microtubules regulate tissue-level navigation in skin-resident macrophages.
journals.biologists.com/jcs/article/...
Article: journals.biologists.com/jcs/article/...

Academic authors, here's a peek into the black box of journal publishing from an journal editor if you can bear it:

Cancer cells are notoriously plastic, but what triggers the changes in cell state? In our new Nature (@nature.com)‬ paper, Miranda Hunter (@mrndhntr.bsky.social‬) found that mechanical pressure is a key to this switch. Check it out here: go.nature.com/47iwDm2

Had thought to test this wild idea in the future but so cool to see Francesca Peri lab making it real: Xenografted human microglia in zebrafish, doing their job 😍https://www.biorxiv.org/content/10.1101/2025.08.27.672578v1.full.pdf

🐟 Zebrafish (Danio rerio): Clear as glass, zebrafish embryos let you watch organs form in real time. A powerhouse for studying organogenesis and regeneration, they’re also champions of transgenic expression of fluorescent proteins 🌈 image from Gopi Shah 🧪 #ModelMonday #DevBio

But not right away at least. And they do not seems to be too unhappy even when stuck with them😉

Repulsive and attractive cues team up to sculpt the retina🔧👁️, Perfect positioning also for your neurons navigating in multipolar manner, no GPS required! Get your free pdf copy of the full story today: www.biorxiv.org/cgi/content/...

2. Attraction through Gfrα1 receptor (HC) and Neurturin secreted from apical photoreceptors.
-Weaker cue ensuring HCs reach the photoreceptors. Take both Neurturin and Robo2 out and majority of HCs (cyan + yellow) are misplaced in the amacrine cell layer (yellow).

1. Repulsion through Robo2 receptor (HC) and Slit1b/2, expressed by the basal amacrine cells (yellow).
-Without Robo2 HCs (cyan + yellow), especially the ones further away from photoreceptor cell layer (grey arrowheads), fail to laminate correctly.

So, what is going on? 🤔 Using transcriptomics, in vivo CRISPR screens and high-res live imaging in a transparent zebrafish retina 👁️, we now introduce “The Spatiotemporal Guidance System🗺️⏰” for multipolar migration with dual action:

But how then to know where to go? A problem many developing neurons face, including the retinal horizontal cells (HCs), we studied.
Neighboring cells as tracks? Removing 3/4 retinal cell types and HCs still navigate correctly. However, take out the 4th type (amacrine cells) and 💥 HCs are stuck.

Interested in cell migration yet bored of the canonical translocation modes? 😴 Don’t worry — we @nordenlab.bsky.social with @aiopticalbiolab.bsky.social have multipolar migration back in stock! No need to follow the other cells: extend long protrusions and roam more freely🪼 in the crowded brain.

Are you looking for a postdoc?
I will be looking for 2-4 people after the summer to join the lab !!
Do not hesitate to reach out and disseminate !!

Whole-body coarticulation reflects expertise in sport climbing Taking sport climbing as a testbed, we explored coarticulation in naturalistic motor-behavior at the level of whole-body kinematics. Participants were instructed to execute a series of climbing routes...

Skimming through biorxiv might improve your climbing?

As a non-expert (climber and in this field), I was taught to climb the route mentally before physically. Movement coordination comes through repetitions as in any sport.🤔

Ever wondered how to manipulate mechanical forces in the developing zebrafish heart?🤓

Check out our new protocol by @cvagenapantoula.bsky.social and Hajime, where we describe magnetic bead grafting as an effective approach to study #mechanotransduction!🐟🔬

app.jove.com/t/67604/mani...

Also thrilled to start today a new chapter in @guijacquemet.bsky.social lab on microglia migration and their protrusion dynamics🧠🐠

After ~3.5 inspiring years @nordenlab.bsky.social, I’ve migrated back to 'apical' Finland. The last months, I appeared a lot like these multipolar retinal cells. Excited to share more soon about their fascinating in vivo navigation!