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Arthur Charles-Orszag @acharlesorszag.bsky.social · 23d

Welcome to our first postdoc in the ACO Lab, Andy Garcia! 🎉

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Arthur Charles-Orszag @acharlesorszag.bsky.social · Sep 1

Supporting each other as #newPI is very important, and @antonioserapio.bsky.social is great at it

Arthur Charles-Orszag @acharlesorszag.bsky.social · Aug 30

🚨 🚨 🗓️ The deadline to submit your abstract for the #ASCB2025 meeting in Philadelphia is this Wednesday, September 3!!
Dyche Mullins and I are hosting the session “Cell Biology at the Extremes”. Thermophiles, psychrophiles, tardigrades, giant bacteria… now is your time to shine!! 🚨

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Arthur Charles-Orszag @acharlesorszag.bsky.social · Jun 25

New hot fluorescent tag dropped!

Arghya Bhowmick @arghya93.bsky.social · Jun 25

Preprint drop! 🚨 Rhobin-tag your proteins and watch Saci glow at high temps! 🔥 Bright, photostable, live-cell imaging made possible with JF dyes. Huge thanks to @samjlord.bsky.social @acharlesorszag.bsky.social @mullinslab.bsky.social and Bo Huang lab at UCSF.😊

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

De novo designed bright, hyperstable rhodamine binders for fluorescence microscopy

De novo protein design has emerged as a powerful strategy with the promise to create new tools. The practical performance of designed fluorophore binders, however, has remained far from meeting fluore...

www.biorxiv.org

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Arthur Charles-Orszag @acharlesorszag.bsky.social · May 30

Thank you!

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Reposted by Arthur Charles-Orszag

Svetlana Dodonova @dodonova-sveta.bsky.social · May 26

We’ve uncovered Asgard chromatin structures formed by a Hodarchaeal histone : closed hypernucleosome conserved in archaea and an open form resembling the H3-H4 eukaryotic octasome. Fantastic work by @harshranawat.bsky.social!
www.biorxiv.org/content/10.1...
#Chromatin #Asgard #Archaea #cryoEM

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Arthur Charles-Orszag @acharlesorszag.bsky.social · May 29

Thanks!

Arthur Charles-Orszag @acharlesorszag.bsky.social · May 29

Archaeal S-layer proteins can adopt different symmetries that can locally accommodate areas of high curvature. The S-layer is also involved in the control of turgor and osmotic pressure, ion transport, cell-cell interactions and mating.

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Arthur Charles-Orszag @acharlesorszag.bsky.social · May 29

The S-layer is the most widespread and fundamental component of archaeal cell envelopes and may represent one of the earliest and most fundamental cell wall polymers found in microorganisms

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Arthur Charles-Orszag @acharlesorszag.bsky.social · May 29

The archaeal S-layer is not only pretty, it also carries crucial cellular functions, and the list keeps growing! @sshamphavi.bsky.social @marleenvw.bsky.social @archaellum.bsky.social and I wrote a little sheath sheet (+10 pts if you got the pun)
📖 Curr Opin Cell Biol
🔗 doi.org/10.1016/j.ce...

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Arthur Charles-Orszag @acharlesorszag.bsky.social · May 29

What a year for the cell biology of archaeal chromosome segregation! 🧬 @joeparham19.bsky.social and @buzzbaum.bsky.social now add pieces to the SegAB puzzle by connecting it with cell division

Joe Parham @joeparham19.bsky.social · May 29

We are excited to share our preprint describing how Sulfolobus cells coordinate DNA segregation with cell division! In eukaryotes this type of regulation involves checkpoints and CDK-cyclins. But how does this work in archaea? This is the question we ask in our paper: www.biorxiv.org/content/10.1...

Temporal and spatial coordination of DNA segregation and cell division in an archaeon.

Cells must coordinate DNA segregation with cytokinesis to ensure that each daughter cell inherits a complete genome. Here, we explore how DNA segregation and division are mechanistically coupled in ar...

www.biorxiv.org

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Reposted by Arthur Charles-Orszag

Joe Parham @joeparham19.bsky.social · May 29

To explore how ring assembly and DNA segregation might be coupled, we turned our attention to the ParA homologue, SegA, and its partner SegB, using antibodies kindly gifted by @acharlesorszag.bsky.social (see www.biorxiv.org/content/10.1...)

Archaeal SegAB forms a bipolar structure that promotes chromosome segregation in spherical cells

Archaeal segAB operons are thought to promote chromosome segregation, but their mechanism remains unknown. We employ comparative genomics, structural biology, genetic knockouts, and quantitative cell ...

www.biorxiv.org

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Reposted by Arthur Charles-Orszag

Archaea Power Hour @archaeapowerhour.bsky.social · May 12

In just 2 days on WEDNESDAY, May 14th at 10 AM EST / 4 PM CET, @fabaiwu.bsky.social will kick off our last spring APH session by telling us about his new research investigating the evolution of DNA replication machineries from Archaea to Eukaryotes!!! Visit our website (link in bio) for more info!

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Reposted by Arthur Charles-Orszag

Archaea Power Hour @archaeapowerhour.bsky.social · May 12

Think you're under pressure? Marion Illartin will close out our last APH session of the semester by telling us about her multidisciplinary approach to characterize how pressure regulates the SurR transcription factor in everyone's favorite barophile, Thermococcus barophilus!! Zoom in on May 14th!

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Arthur Charles-Orszag @acharlesorszag.bsky.social · May 8

Don’t miss it!! Last APH of the season 🫶🏼

Archaea Power Hour @archaeapowerhour.bsky.social · May 8

Tune in for our last (😭) APH session of this semester next WEDNESDAY, May 14th, at 10 AM EST / 4 PM CET!!! Check your email soon for the Zoom link or sign up to join our mailing list here: t.co/b17JFAaZQ6. Check out the exciting talks we have planned for you:

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Arthur Charles-Orszag @acharlesorszag.bsky.social · May 8

Oop!

Arthur Charles-Orszag @acharlesorszag.bsky.social · May 7

If I may weigh in here: I avoid overfixing the cells, especially if using glutaraldehyde that can induce significant artefacts. I usually do 30-60 min at RT and rinse abundantly in buffer. Fixed cells in buffer can then be kept for days in the fridge :)

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Arthur Charles-Orszag @acharlesorszag.bsky.social · May 7

Hahaha awww 🫶🏼 I’m very ignorant when it comes to anaerobic cultures. What are the challenging steps pre-fixation? The spinning?

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Arthur Charles-Orszag @acharlesorszag.bsky.social · May 7

6) in all subsequent rinsing and post-fixation steps, avoid drying the cells as much as possible. We never discard the full volume of liquid in the wells. Instead, we only discard 80-90% but make up for it by performing more rinsing steps

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Arthur Charles-Orszag @acharlesorszag.bsky.social · May 7

5) add an equal volume of a 2X fixative solution in adequate buffer, or ideally in culture media, as opposed to removing the media and then adding 1X fixative to the cells

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Arthur Charles-Orszag @acharlesorszag.bsky.social · May 7

4) spin the plate containing the cells/coverslips (24-well plate, 13 mm coverslips in our hands) at 1,000xg for 2 min to increase cell density on the coverslip

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Arthur Charles-Orszag @acharlesorszag.bsky.social · May 7

3) incubate high OD live cultures on coated coverslips for 30-60 min to allow plenty of cells to settle. It works better than trying to adhere chemically fixed cells.

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Arthur Charles-Orszag @acharlesorszag.bsky.social · May 7

2) try poly-D-lysine instead. Sometimes it just works!

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Arthur Charles-Orszag @acharlesorszag.bsky.social · May 7

You can enhance adhesion by doing any, or a combination, of the following:

1) plasma treat the glass coverslips before coating them with poly-L-lysine (30 min at RT). This greatly enhance coating strength. Make sure to rinse with plenty of water before adding live cells

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Arthur Charles-Orszag @acharlesorszag.bsky.social · May 1

I’m already on it! 🤓

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