Dave Baltrus 🦦

Dave Baltrus 🦦

@surtlab.bsky.social

Professor at UArizona interested in genome rummaging, microbial evolution, and occasional tales about having backyard farm animals. “I’m something of a scientist myself” Baltrus(at)Arizona.edu

8K followers3.1K following2.3K posts

Dave Baltrus 🦦 reposted

Brian Stevenson Ph.D. spirochete lab
@bstevensonlab.bsky.social

A plasmid that’s 1.58 million base pairs long, about 30X the size of a typical E. coli plasmid. Its relatives were found in hundreds of microbiomes worldwide. #MicroSky

Allison G@assemblerag.bsky.social

Out now in @natcomms.nature.com: We found a plasmid in a preterm infant’s gut microbiome that’s 1.58 million base pairs long, about 30X the size of a typical E. coli plasmid. Then we found its relatives in hundreds of microbiomes worldwide. Read on to learn more about the elusive pMEGAs! 🧵

nature.comIdentification and genetic characterization of megabase-scale plasmids of Enterobacteriaceae - Nature CommunicationsHere, the authors report the identification and characterization of large, up to 1.58 million base-pair-long plasmids in gut microbiomes worldwide, showing that while most genes remain uncharacterized...
Dave Baltrus 🦦
@surtlab.bsky.social

Look, I love me some Cheesecake Factory But there’s no way that Scott Bessent likes the cheesecake factory and it makes me happy that he’s likely hating every minute of doing this for Dear leader Also, the Obama joke was about the tacky Cheesecake Factory decoration not anything else about it

David S. Bernstein @dbernstein.bsky.social

You really need to work hard to be the most obsequious member of Trump’s cabinet — by, for instance, eating lunch at Cheesecake Factory and alerting Fox Business, so they can interview you in defense of Obama’s joke about the White House decor. Well done Secretary Bessent! Your move, Doug Burgum!

Dave Baltrus 🦦
@surtlab.bsky.social

This feels pretty spot on…

Harmit Singh Malik@harmitmalik.bsky.social

When I was a student moving from engineering to biology, I often heard that I was moving to a ‘soft science.’ Whereas physics and chemistry and mathematics had ground truth rules that were true no matter what, biology seemed like anarchy by comparison.

Dave Baltrus 🦦 reposted

Laurie Voss
@seldo.com

And now back to my full time job, texting the word "stop" to every living Democrat.

Dave Baltrus 🦦 reposted

Joao Ascensao
@joaoascensao.bsky.social

Now published! doi.org/10.1126/scia...

doi.orgFrequency-dependent fitness effects are ubiquitous in rapidly adapting microbial populationsIn simple microbial populations, the fitness effects of selected mutations are typically assumed to be constant, regardless of mutant frequency. This assumption underpins predictions about evolutionar...
Joao Ascensao@joaoascensao.bsky.social

How common are frequency dependent fitness effects? New preprint out today 👇 doi.org/10.1101/2025...

doi.orgFrequency-dependent fitness effects are ubiquitousIn simple microbial populations, the fitness effects of most selected mutations are generally taken to be constant, independent of genotype frequency. This assumption underpins predictions about evolutionary dynamics, epistatic interactions, and the maintenance of genetic diversity in populations. Here, we systematically test this assumption using beneficial mutations from early generations of the Escherichia coli Long-Term Evolution Experiment (LTEE). Using flow cytometry-based competition assays, we find that frequency-dependent fitness effects are the norm rather than the exception, occurring in approximately 80\% of strain pairs tested. Most competitions exhibit negative frequency-dependence, where fitness advantages decline as mutant frequency increases. Furthermore, we demonstrate that the strength of frequency-dependence is predictable from invasion fitness measurements, with invasion fitness explaining approximately half of the biological variation in frequency-dependent slopes. Additionally, we observe violations of fitness transitivity in several strain combinations, indicating that competitive relationships cannot always be predicted from fitness relative to a single reference strain alone. Through high-resolution measurements of within-growth cycle dynamics, we show that simple resource competition explains a substantial portion of the frequency-dependence: when faster-growing genotypes dominate populations, they deplete shared resources more rapidly, reducing the time available for fitness differences to accumulate. Our results demonstrate that even in a simple model system designed to minimize ecological complexity, subtle ecological interactions between closely related genotypes create frequency-dependent selection that can fundamentally alter evolutionary dynamics. ### Competing Interest Statement The authors have declared no competing interest.

Dave Baltrus 🦦 reposted

Greg Sargent
@gregsargent.bsky.social

I really like the point made here: Dems should be making a public case right now for novel tactics like defunding Trump's corrupt prosecutions, to make them more intelligible later:

Nicholas Grossman@nicholasgrossman.bsky.social

Democrats laying the groundwork for real opposition, with Congress asserting budget authority to stand against Trump abuses and rights violations. Will have to overcome cries that not passing Trump's budget is irresponsible. But it's the opposite. And starting now makes that hurdle easier to clear.

Dave Baltrus 🦦 reposted

STCmicrobeblog
@stcmicrobeblog.bsky.social

(bacterial) chromosome replicationists take note👇 #MicroSky

Ernesto Arias-Palomo@eariaspalomo.bsky.social

🧬 How do bacteria open a molecular ring to start DNA replication? Excited to share our new work in @narjournal.bsky.social @academic.oup.com, where we reveal how the ancestral helicase loader DciA opens the replicative helicase DnaB. @cib-csic.bsky.social 🧵👇 🔗 academic.oup.com/nar/article/...

Dave Baltrus 🦦
@surtlab.bsky.social

2016 would’ve gone so different in the US if we had secondary run off elections….

Taniel@taniel.bsky.social

In Brazil, it appears that voters who opted for eliminated first-round candidates roughly broke even in the runoff (even if the candidates leaned right). But the big difference was: Millions of voters who cast 'null' or 'blank' ballots in the first round then voted for Lula.

Dave Baltrus 🦦 reposted

Joshua Weitz
@joshuasweitz.bsky.social

Happy World Phage Day to all who celebrate... ... delighted to share new work led by Jacopo Marchi, Chadiga Khalek & joint w/Remy Chait on stable coexistence of phage with migrating bacteria driven by the forces of infection, lysis, and chemotaxis. A 🧵 at the interface between known & unknown.

science.orgStable coexistence and transport of lytic phage infections with migrating bacterial hostsBacteriophages (phages), viruses that exclusively infect bacteria, coexist with their bacterial hosts across diverse environments at densities exceeding 107 per milliliter in marine surface waters, 10...

Dave Baltrus 🦦 reposted

Micah
@rincewind.run

Obama is still the most gifted political communicator of my lifetime and it isn’t particularly close

Aaron Rupar@atrupar.com

“How much time do you think this defense secretary spends looking in the mirror in the morning? These are not serious people” — Obama’s audience in Ohio is hanging on every word as he skewers Trump and Hegseth

Dave Baltrus 🦦
@surtlab.bsky.social

It’s weird that (for the first time I can remember) a majority of places I went to in Belgium this week had tipping on the check as an option….did we Americans export that?

Dave Baltrus 🦦 reposted

Rodger Sherman
@rodger.bsky.social

Replying to @rodger.bsky.social

You almost definitely know at least one person who is alive that would have died if not for the medical advances that have taken place since you were born. You might not even realize it!

Dave Baltrus 🦦 reposted

Rodger Sherman
@rodger.bsky.social

The world is scary and we need to fix a lot but broadly life is better and more comfortable now than at any point in human history. Medicine is better, people live longer, planes crash less, things work better, food is better, the list goes on

Michael Druker 🇨🇦@mdruker.app

Social media loves talking about how everything is getting worse. But what’s something that you’ve seen get _better_ in your lifetime?

Dave Baltrus 🦦 reposted

Ed
@notdred.bsky.social

This is quite simply not going to work, and in the process of not working is going to reach absolutely horrific levels of animal cruelty

Amy Feldman@amyfeldman7.bsky.social

*NEW* Colossal Biosciences’ Ben Lamm and Anduril’s Palmer Luckey team up on a new startup to genetically engineer war dogs for the military. Warhound comes out of stealth at $1.2B valuation For @forbes.com with @iainmartin.bsky.social and @mhunterhart.bsky.social www.forbes.com/sites/amyfel...

forbes.comBillionaires Palmer Luckey And Ben Lamm Spin Up Startup To Genetically Engineer Military DogsBen Lamm of de-extinction startup Colossal has teamed up with Palmer Luckey’s team at Anduril to create a dog that’s optimized for military use. The new “warhounds” will be cloned and gene edited.

Dave Baltrus 🦦 reposted

Adam Rogers
@jetjocko.bsky.social

And yes, I feel like a putz arguing that one lesson of Theranos is that journalism has to be less credulous the same week Tesla claims to have a car that flies and Colossal claims it’s going to make the cyberdog from Diamond Age.

Dave Baltrus 🦦 reposted

Tom Scocca
@tomscocca.bsky.social

One thing about all these techies fired up to gene-engineer dogs or their own offspring or other living commodities is that none of them know how a genome works

Dave Baltrus 🦦
@surtlab.bsky.social

It hurts my brain trying to think about the genetics conversations these people are all having behind closed doors Like the conversations are probably idiotic like “we need to make dogs that have high T” But also evil and definitely not just focused on dogs

Piali Sengupta@senguptalab.bsky.social

What a colossal waste of money

Dave Baltrus 🦦 reposted

Carl T. Bergstrom
@carlbergstrom.com

If you thought Ben Lamm was a shithead, you underestimated him. He's worse. Genetically engineering any creatures, but dogs especially, to be weapons of war — it's unspeakable. www.forbes.com/sites/amyfel...

forbes.comBillionaires Palmer Luckey And Ben Lamm Spin Up Startup To Genetically Engineer Military DogsBen Lamm of de-extinction startup Colossal has teamed up with Palmer Luckey’s team at Anduril to create a dog that’s optimized for military use. The new “warhounds” will be cloned and gene edited.
Dave Baltrus 🦦
@surtlab.bsky.social

Can’t find the post right now, but t kinda called it a few months ago that designer pets would ultimately be colossal’s goal for $$$$$ Obviously this is completely evil

Amy Feldman@amyfeldman7.bsky.social

*NEW* Colossal Biosciences’ Ben Lamm and Anduril’s Palmer Luckey team up on a new startup to genetically engineer war dogs for the military. Warhound comes out of stealth at $1.2B valuation For @forbes.com with @iainmartin.bsky.social and @mhunterhart.bsky.social www.forbes.com/sites/amyfel...

forbes.comBillionaires Palmer Luckey And Ben Lamm Spin Up Startup To Genetically Engineer Military DogsBen Lamm of de-extinction startup Colossal has teamed up with Palmer Luckey’s team at Anduril to create a dog that’s optimized for military use. The new “warhounds” will be cloned and gene edited.

Dave Baltrus 🦦 reposted

Micah
@rincewind.run

how all of these conversations would actually go

Philip Bump@pbump.com

Even if this were viable as a concept (that there's an afterlife; that it allows conversations with others; that enslavers are going the same place as you), who cares? Oh, are you mad at me, Ben Franklin? Tough shit.

Dave Baltrus 🦦 reposted

Jon Douglas
@atranscendedman.bsky.social

Bar-Ilan University researchers found that antibiotics can directly alter immune function, even without gut bacteria. In mice, vancomycin changed feeding behavior, disrupted biological clocks, and suppressed immune-related gene expression in the colon. www.nature.com/articles/s41...

nature.comDisentangling microbiota-dependent and -independent impacts of antibiotics on host physiology - Nature MicrobiologyUsing a computational tool called CompoRes, the authors show that antibiotics can alter feeding behaviour, immunity and circadian regulation, revealing a non-microbial pathway by which antibiotic trea...

Dave Baltrus 🦦 reposted

Willem van Schaik
@wvschaik.bsky.social

I have spent 20 years telling myself, and the people I work with, to not put too much text on slides, and use at least 20 picas font size. But now it looks like ChatGPT's integration with Powerpoint is destroying scientific presentations. Insanely complex slides, poor visuals and so much text.

Dave Baltrus 🦦 reposted

Ran Blekhman
@blekhman.bsky.social

Some of my thoughts about the surge in AI-generated papers, why this feels like a completely new kind of problem, and what this means for how we evaluate science in biology. Out now in PLOS Biology: journals.plos.org/plosbiology/...

journals.plos.orgWhat is biology research for?In the age of generative artificial intelligence (AI), the assumption that writing a paper requires doing science no longer holds true. Before deciding how to respond to the surge of AI-generated pape...

Dave Baltrus 🦦 reposted

Trends in Plant Science
@cp-trendsplantsci.bsky.social

The redox–phytohormone nexus, illustrated by the jasmonate paradigm #plantscience

dlvr.itThe redox–phytohormone nexus, illustrated by the jasmonate paradigmRedox-sensitive protein switches and transcriptional networks are integral to phytohormone signaling networks. The jasmonate (JA) signaling pathway, which incorporates the coronatine insensitive 1 (COI1)–Jasmonate ZIM-domain (JAZ) co-receptor and the MYC2 transcription factor, is a relatively recent evolutionary innovation that has emerged only in land plants. Earlier JA signaling systems relied on electrophilic oxylipins, such as 12-oxo-phytodienoic acid (OPDA) and dinor-12-oxo-10,15(Z)-phytodienoic acid (dn-OPDA), and reactive oxygen species (ROS), particularly H2O2. All plant 14-3-3 proteins, such as General regulatory factor 8 (GRF8), contain a conserved redox-sensitive cysteine. Sulfenylation of GRF8 relieves inhibition of MYC2, thereby facilitating JA signaling in arabidopsis (Arabidopsis thaliana). This mechanism may represent a primordial oxylipin signaling system, overlain by the more recent COI1–JAZ system, revealing hormone signaling plasticity that can be targeted for engineering stress-resilient crops.

Dave Baltrus 🦦 reposted

PLOS Biology
@plosbiology.org

The ratio of nonsynonymous to synonymous DNA substitutions (dN/dS) encodes information about selection pressures. This study develops a model of dN/dS in recombining bacterial populations, offering insights on how horizontal gene transfer shapes the genome. 🧪 #AcademicSky #evolution plos.io/3Wcy9lT