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Reposted by Sophie G Martin

University of Cambridge @cam.ac.uk · 1d

It is with great sadness that the University shares the news of the death of Professor Sir John Gurdon, founder of the @gurdoninstitute.bsky.social

Read our tribute to the visionary Nobel Laureate and watch an interview from 2012, just after he won: https://bit.ly/4mM8o3r

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Sophie G Martin @sophiemartinlab.bsky.social · 10d

@biology-unige.bsky.social

Sophie G Martin @sophiemartinlab.bsky.social · 10d

Amazingly, her work also led to Sms1, which @borissieber.bsky.social had identified by biochemical means and found to be the long sought-after MAPK scaffold.

Very satisfying to come to the same gene through completely different routes! 😀

bsky.app/profile/bori...

Boris Sieber @borissieber.bsky.social · 13d

Mammalian cells have KSR, budding yeast has Ste5… and fission yeast has Sms1 as the MAPK scaffold for sexual reproduction!

Very excited to share my postdoc work where we discover that the hemi-arrestin Sms1 binds all components of the MAPK cascade, including ERK-like Spk1

doi.org/10.1101/2025...

Schematic of MAPK signalling in fission yeast, budding yeast and Metazoa. No MAPK scaffold was known for ERK-like MAPK in fission yeast, as opposed to budding yeast Ste5 and metazoan KSR1/2.

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Sophie G Martin @sophiemartinlab.bsky.social · 10d

Starting from cells strongly impaired for cell fusion (lacking the gene prm1), she evolved enhanced cell fusion capacity, which she showed occurs through both changes in regulatory pathways that lead to increasing fusion attempts, and also through emergence of a latent pathway.

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Sophie G Martin @sophiemartinlab.bsky.social · 10d

Super happy to see also this story out! 👇

7 years of amazing perseverance from @gaowen.bsky.social, who not only performed experimental evolution showing tradeoff between sexual and asexual reproduction, but also identified all key transcription and genome changes.

www.biorxiv.org/content/10.1...

Gaowen Liu @gaowen.bsky.social · 10d

Sex or growth? Life must continually balance these strategies. We forced yeast to choose and captured the trade-off in real time. Evolution rewired existing regulators and fixed them through genetic assimilation, creating specialists for sex at the cost of growth.
www.biorxiv.org/cgi/content/...

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Sophie G Martin @sophiemartinlab.bsky.social · 13d

Thanks! We know your papers well! 😀

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Sophie G Martin @sophiemartinlab.bsky.social · 13d

Super excited that this story by @borissieber.bsky.social is now on BioRxiv!

For decades, we thought there was no MAPK scaffold for the ERK-like cascade that promotes sexual reproduction in fission yeast ... until Boris found it !

See the thread 👇 and enjoy the paper!

doi.org/10.1101/2025...

Boris Sieber @borissieber.bsky.social · 13d

Mammalian cells have KSR, budding yeast has Ste5… and fission yeast has Sms1 as the MAPK scaffold for sexual reproduction!

Very excited to share my postdoc work where we discover that the hemi-arrestin Sms1 binds all components of the MAPK cascade, including ERK-like Spk1

doi.org/10.1101/2025...

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Reposted by Sophie G Martin

Sebastian Soyk @sebastiansoyk.bsky.social · 21d

Our department of Plant Molecular Biology at the University of Lausanne @unil.bsky.social is recruiting a Tenure-Track Assistant Professor in the field of Plant-Organism Interactions 🌱🐛🦠🍄! Application before November 30, 2025. See the official job ad for more details: tinyurl.com/mtxdcz6p

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Reposted by Sophie G Martin

Marko Kaksonen @kaksonen.bsky.social · Jul 7

Hello microscopy and imaging experts and enthusiasts!
We are looking for a staff scientist to join us here in Geneva to work on microscopy and image analysis projects! See the link for the job announcement (in French and in English).

Please apply and/or repost!

jobs.unige.ch/www/wd_porta...

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Reposted by Sophie G Martin

Omaya Dudin 𓂆 ¦🍉¦🦠¦🔬¦ @dudinlab.bsky.social · Jul 8

Come and Join our Dpt in Beautiful #Geneva !

We are looking for a #Microscopy & #Image #Analysis expert to help all of us at the Dpt.

Marko Kaksonen @kaksonen.bsky.social · Jul 7

Hello microscopy and imaging experts and enthusiasts!
We are looking for a staff scientist to join us here in Geneva to work on microscopy and image analysis projects! See the link for the job announcement (in French and in English).

Please apply and/or repost!

jobs.unige.ch/www/wd_porta...

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Reposted by Sophie G Martin

Marko Kaksonen @kaksonen.bsky.social · Jun 24

How do cells switch on the actin assembly at endocytic sites? How can this on-switch evolve? Check out our new preprint!
www.biorxiv.org/content/10.1...

Localization of WDS proteins and fimbrin in three fungal species.

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Sophie G Martin @sophiemartinlab.bsky.social · Jul 4

Congrats Monica! This is amazing 🤩

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Reposted by Sophie G Martin

Paul & Virginie - Centriole Lab @centriolelab.bsky.social · Jun 19

🚨 New preprint!
Using U-ExM + in situ cryo-ET, we show how C2CD3 builds an in-to-out radial architecture connecting the distal centriole lumen to its appendages. Great collab with @cellarchlab.com @chgenoud.bsky.social @stearnslab.bsky.social 🙌. #TeamTomo #UExM
www.biorxiv.org/content/10.1...

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Reposted by Sophie G Martin

Christian Fankhauser @chfankhauser.bsky.social · Jun 16

Great job opportunity at The Center for Integrative Genomics, Lausanne University, Switzerland unil.ch/cig/en/home....
For a tenure-track Assistant Professor position. More details for how to apply are here nature.com/naturecareer...

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Reposted by Sophie G Martin

Jan-Willem Veening @veeninglab.com · Jun 10

New tenure track assistant professor position in molecular microbiology in our department @dmf-unil.bsky.social @unil.bsky.social! We are casting a wide net for an experimental molecular microbiologist. Apply here: wwwfbm.unil.ch/releve/appli...

DMF: Tenure Track Assistant Professor towards Associate Professor in Molecular Microbiology - Site des postulations FBM

wwwfbm.unil.ch

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Sophie G Martin @sophiemartinlab.bsky.social · May 16

Beautiful images 🤩

Saravanan Palani @syncellbiolab.bsky.social · May 16

Preprint: IntAct-U-ExM enables robust, isoform-specific expansion microscopy of actin networks in yeast and mammalian cells. A cool study led by @anubhavdhar.bsky.social in collaboration with Sudarshan and Deepak Nair. www.biorxiv.org/content/10.1...

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Reposted by Sophie G Martin

Sophie G Martin @sophiemartinlab.bsky.social · May 2

New lab preprint! High resolution mapping of the actin fusion focus reveals myosin V-dependent transport of formin for actin aster compaction.

A very cool work led by @valthomas.bsky.social and nice collaboration with Andrea Picco and @kaksonen.bsky.social!

www.biorxiv.org/content/10.1...

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Sophie G Martin @sophiemartinlab.bsky.social · May 9

Congrats Caren! Back to the source!

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Sophie G Martin @sophiemartinlab.bsky.social · May 6

The surprise is that, over the same fold-change, cellular dimensions vary linearly with Cdc42 protein levels. So polarized growth has a linear relationship with Cdc42 levels.

➡️ Open question: How does this match with all the positive and negative feedback regulation that control Cdc42 activity?

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Sophie G Martin @sophiemartinlab.bsky.social · May 6

To test the importance of protein levels, we created an allelic series, exploring a 5-fold range in Cdc42 expression levels.

We found that Cdc42 levels exhibit a switch-like transition for function during sexual reproduction, going from sterile to fully fertile cells within a 2-fold change.

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Sophie G Martin @sophiemartinlab.bsky.social · May 6

With several variants of cdc42 exhibiting cell fusion defects, including a widely used tagged allele (cdc42-mCherrySW) and mutants in cdc42 introns, we realized what they had in common: low levels of Cdc42 protein expression.

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Sophie G Martin @sophiemartinlab.bsky.social · May 6

We found that Cdc42 GTPase localizes to the site of cell-cell fusion in S. pombe cells (arrow in image) and plays important roles in the late stages of polarized secretion to promote local cell wall digestion.

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Sophie G Martin @sophiemartinlab.bsky.social · May 6

The lab is on a roll. 2nd preprint in as many weeks!

High levels of Cdc42 GTPase underlie an all-or-none decision to fuse.

Great team effort led by PhD students @sajjitasaha.bsky.social and @aiswaryasajeevan.bsky.social

www.biorxiv.org/content/10.1...

@biology-unige.bsky.social

High levels of Cdc42 GTPase underlie an all-or-none decision to fuse

Cdc42 is a Rho-family GTPase conserved across eukaryotes, where it plays essential roles in cell polarization. In single-celled yeast systems, Cdc42 is a key driver of symmetry breaking and polarized ...

www.biorxiv.org

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Sophie G Martin @sophiemartinlab.bsky.social · May 5

Thanks Omaya!

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Sophie G Martin @sophiemartinlab.bsky.social · May 2

Does this mechanism ring a bell?
It is conceptually remarkably similar to how spindle poles form. It seems like the same principles apply to form cytoskeletal asters, whether based on actin or microtubules.

#actin #microtubules #cytoskeleton

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