Mendelspod Podcast

Fei Chen of the Broad Institute describes the original problem simply: genomics gave us powerful inventories of gene expression, while microscopy gave us structure—yet the two lived in separate worlds. “You could either have your structure or you could have gene expression, but you couldn’t have both.”
In this conversation, Fei walks us through how Slide-tags—now commercialized as Takara Bio Trekker technology—set out to close that gap. Instead of mapping gene expression onto a grid, his team flipped the problem: barcoding the cells in place, then reading them out with single-cell sequencing. The result is something closer to a GPS system for cells.
What this unlocks is not just better maps, but better biology. Better questions. In cancer, Fei describes the discovery of local immune “circuits” that determine whether tumors respond to immunotherapy. And more broadly, spatial data turns tissue itself into a kind of experiment itself. Is this the biology of the future? “The spatial context is a natural experiment that has happened.”
Chapters:
0:00 The problem: structure vs gene expression1:36 A GPS for cells8:59 Immune circuits and cancer response20:04 Tissue as experiment26:24 New questions for biology
Across applications, Fei emphasizes that the real shift is conceptual. Spatial biology is not just about adding location to sequencing. It’s about learning how to ask new questions—ones that treat cells not as isolated units, but as participants in research.



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Peptides are having a moment.
But beneath the market excitement and the GLP-1 headlines, something more interesting is going on. A field that for years seemed technically promising but perpetually constrained is becoming wide open.
To see into that open terrain, we’re joined by Charlie Johannes, founder of EPOC Scientific and president of the Peptide Drug Hunting Consortium, along with Tomi Sawyer, a founder of the Consortium and founder of Maestro Therapeutics. We asked them for a high-level look at a field being reshaped by advances in chemistry, screening, delivery, and by a growing sense that peptides may be uniquely positioned to open up biology that other modalities have only partly been able to reach.
And yet both are clear: the field is not mature. AI is accelerating biology, which still depends on existing knowledge. Prediction remains limited, especially with non-natural chemistry. And the core challenge may now be human—how to turn an overwhelming amount of data into real innovation. As Johannes puts it, “Turning knowledge into innovation is the real challenge.”
Chapters:
1:31 Why peptides are suddenly hot again6:10 Between small molecules and biologics10:14 Oral delivery, screening15:45 AI, automation, and the limits of prediction32:17 The Consortium and where the field is heading
This is not a finished revolution—it’s a launch. The field, Sawyer says, is “in the Artemis II rocket right now heading towards the moon.” The peptide story is now much bigger than obesity drugs. Where does the field stand today? What has changed, and what remains difficult?
This episode is the first in a new partnership between Mendelspod and Peptide and Protein News, a media platform covering peptide and protein drug development. You can see what they’re up to at peptideandprotein.com.


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It was the biggest story in sequencing last year: Mark Kokoris, head of SBX sequencing at Roche and inventor of the technology, joins Mendelspod to talk about how Sequencing by Expansion (SBX) works and why it may redefine the limits of genomics.
* 0:00 A long journey inspired by PCR
* 7:20 What is sequencing by expansion?
* 14:00 On scale and accuracy
* 19:40 Multi-omics vision?
* 24:40 What will be the killer app?
* 30:00 Biggest challenge for launch
Kokoris recounts the long path from co-founding Stratos Genomics in 2007 to Roche’s acquisition in 2020, when his team’s “wildly ambitious chemistry” finally found its match in Genia’s high-density nanopore platform. “Our approach to efficiently sequencing DNA,” he explains, “is to not sequence DNA. We rescale the problem—expand the molecule about 50-fold—so we can read it with much higher signal-to-noise.”
The result is astonishing speed. Working with the Broad Institute and Boston Children’s Hospital, SBX delivered whole-genome results in under four hours, with the sequencing step itself taking only about 15 minutes. Kokoris attributes the achievement to a confluence of chemistry and compute.
SBX’s duplex mode achieves Illumina-level accuracy (F1 > 99.8 %) while maintaining single-molecule simplicity. Its tunable flexibility lets small labs run a handful of samples in hours or large centers run thousands per day. Kokoris describes it as a technology built on impatience and rule-breaking, designed to give scientists options they’ve never had.
Looking ahead to the 2026 research-use launch, he’s characteristically bold:
“For me, success means SBX becoming the new standard in sequencing. Innovation can’t stop—it has to keep evolving, because biology is complex and we’ve got a lot more to do.”
This show was originally published Nov 11, 2025.


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Why do some animals live ten times longer than others?
That question opens today’s interview with Steve Austad, Distinguished Professor at the University of Alabama at Birmingham and one of the leading thinkers in the biology of aging. It quickly becomes clear why he’s been such an important voice in bringing aging research from the margins into the center of science. As he puts it, the field was once “where scientists went to die,” but with modern genetic and molecular tools, it has become one of the most active areas in biomedicine.
Steve’s approach, laid out in his book for the empiricist (I’m an amateur), Methuselah’s Zoo, is deceptively simple: look at the animals. From birds and bats to clams that live for centuries, he shows that lifespan follows a clear evolutionary logic. Safer, more stable environments favor slower aging. “If it’s unstable and unsafe… it makes sense… to reproduce fast,” he explains, while protected environments allow organisms to invest in long-term maintenance. It’s a framework that turns curiosity into theory—and theory into something testable.
Chapters:
1:31 Where scientists went to die4:11 The opossum problem8:00 Air, land, sea14:23 The longevity quotient33:30 Not forever, just longer
What makes Steve such a compelling guide is his tone. He’s low-key, almost amused at times, but unwavering on the science. Aging, he reminds us, isn’t programmed for our benefit—“evolution does not care how long you live.” That doesn’t mean we can’t intervene. The field is now moving into human trials, even if key tools like aging clocks are still imperfect. He has little patience for talk of immortality—calling it “completely delusional.” Still, he’s optimistic. Adding a decade or two of healthy life—not forever—is the goal today.


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Molecular residual disease, or MRD, has been part of oncology’s vocabulary for decades. But knowing something is there and being able to measure it precisely are two very different things. In today’s show, we explore how MRD testing moved from a long-standing clinical suspicion to one of the most consequential tools in modern oncology.
Joining us on the program are Chris Hourigan, Director of the Fralin Biomedical Research Institute Cancer Research Center (DC) at Virginia Tech, bringing the academic and clinical AML lens, and Gary Pestano, Chief Scientific Officer at Biodesix, offering the industry and diagnostic development perspective.
Hourigan reminds us that MRD itself isn’t new. What was missing were the tools. From counting cells under a microscope to flow cytometry and now highly sensitive molecular techniques including droplet digital PCR, MRD has evolved into a quantitative, actionable signal.
Coming from the side of commercializing and scaling assays, Pestano underscores the central challenge of distinguishing meaningful signal from background noise. “There is a lot circulating in our blood. The key is what is meaningful, what is not meaningful,” he explains. Sensitivity alone isn’t enough. Target selection, bioinformatic filtering, validation at scale, and real-world reproducibility all determine whether MRD can truly guide care.
The field is very much still work in progress, say both.
Looking ahead, they point toward quantification as the next frontier. MRD is no longer just about detecting what remains. It’s about deciding what happens next.
“We’ve been talking about MRD as if it’s a binary concept” says Hourigan. “I can imagine in the future, there’s going to be windows, and we will tune therapy to what comes next.”
Thank you to Bio-Rad for sponsoring today’s show. Bio-Rad is your trusted partner for absolute quantification and reproducible results in oncology research. Bio-Rad helps you move from data to confident decisions. Learn more at bio-rad.com/oncology.


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