Base by Base

Khosh Abady K et al., PNAS - Spectroscopic comparison of thymine and uracil under 265 nm UVC shows thymine is more photoreactive and absorbs more primordial UVC, yet channels damage into reversible CPDs rather than irreversible (6-4) lesions, supporting an evolutionary 'molecular sunscreen' role. Key terms: UV photodamage, thymine, uracil, cyclobutane pyrimidine dimer, origin of life.

Study Highlights:
The authors used absorption, fluorescence, and Raman spectroscopy with 265 nm UVC irradiation to compare thymine and uracil photochemistry under controlled conditions. Thymine shows a faster overall absorbance decay (k = 0.174 min−1) than uracil (k = 0.064 min−1) and ~9% broader, redshifted absorption that increases overlap with primordial UVC. Thymine exhibits ~4.5× stronger intrinsic fluorescence and produces higher-amplitude photoproduct fluorescence while accumulating irreversible (6-4) photoproducts more slowly (k = 1.56 min−1) than uracil (k = 2.04 min−1). Raman markers distinguish CPD and (6-4) pathways and indicate thymine preferentially funnels damage into reversible CPD formation amenable to nonenzymatic self-repair.

Conclusion:
Thymine, though more photoreactive and exposed to higher primordial UVC flux, appears evolutionarily selected to localize UV damage into reversible lesions (CPDs) and provide molecular 'sunscreen' protection while enabling nonenzymatic self-repair, complementing later biochemical fidelity mechanisms.

Music:
Enjoy the music based on this article at the end of the episode.

Article title:
UV photodamage pathways and the evolutionary selection of thymine over uracil in early genetic systems

First author:
Khosh Abady K

Journal:
PNAS

DOI:
10.1073/pnas.2615278123

Reference:
Khosh Abady K, Karpourazar N, Rentzepis PM. UV photodamage pathways and the evolutionary selection of thymine over uracil in early genetic systems. PNAS. 2026. doi:10.1073/pnas.2615278123

License:
This episode is based on an open-access article published under the Creative Commons Attribution 4.0 International License (CC BY 4.0) – https://creativecommons.org/licenses/by/4.0/

Support:
Base by Base is independent and ad-free — no sponsors, no paywall. If an episode was worth your time, chip in and keep the papers audited and the original songs coming:
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More at basebybase.com

On PaperCast Base by Base you'll discover the latest in genomics, functional genomics, structural genomics, and proteomics.

Episode link: https://basebybase.com/episodes/uv-photodamage-thymine-vs-uracil

QC:
This episode was checked against the original article PDF and publication metadata for the episode release published on 2026-08-22.

QC Scope:
- article metadata and core scientific claims from the narration
- excludes analogies, intro/outro, and music
- transcript coverage: Audited transcript sections: background on RNA world and thymine vs uracil, experimental design with frozen-state bases, absorption/fluorescence/Raman results, and interpretation including CPD vs (6-4) pathways, molecular sunscreen hypothesis, evolutionary implications, and applications to pathogen detection/UV disinfe
- transcript topics: RNA world background and thymine vs uracil photochemistry; Experimental design: frozen-ice state, 130 µM concentration, 265.3 nm narrowband UVC LED, -15 °C; Absorption spectra and photodegradation kinetics (k values for thymine and uracil); Fluorescence kinetics and photoproduct formation; Raman signatures for CPD and (6-4) photoproducts; Methyl group effects on base stacking and CPD bias

QC Summary:
- factual score: 10/10
- metadata score: 10/10
- supported core claims: 5
- claims flagged for review: 0
- metadata checks passed: 4
- metadata issues found: 0

Metadata Audited:
- article_doi
- article_title
- article_journal
- license

Factual Items Audited:
- Thymine absorbs at 265 nm; uracil at 259 nm; thymine's absorption band ~9% broader than uracil's
- Concentration used for tests: 130 µM for both thymine and uracil
- Irradiation conditions: 265 nm LED, FWHM ≈ 12 nm, irradiance 0.6 mW/cm2
- Sample temperature: −15 °C (frozen-state irradiation)
- Decay kinetics: thymine k = 0.174 min−1; uracil k = 0.064 min−1
- Photoproduct formation bands: thymine photoproduct ≈315 nm (absorption) and ≈378 nm (fluorescence); uracil photoproduct ≈300 nm (absorption) and ≈372 nm (fluorescence)

QC result: Pass.

Pilgrim C et al., PNAS - A minimal analytical model shows that whether animal groups adopt distributed low-level vigilance (many-eyes) or concentrated high-vigilance roles (sentinels) depends on how individual vigilance costs scale with effort. The same dichotomy appears in selfish and cooperative groups and explains switching, edge effects, and turn-taking. Key terms: collective vigilance, many-eyes, sentinel behavior, vigilance costs, behavioral ecology.

Study Highlights:
The authors derive a minimal model where collective vigilance benefit is a function of summed individual vigilance and costs depend on individual effort. When vigilance costs are convex (steepening) many-eyes strategies with equal low vigilance across individuals are optimal; when costs are concave (flattening) sentinel strategies with vigilance concentrated in one or a few individuals are optimal. This outcome holds in both selfish (game-dynamic) and cooperative (group-optimal) contexts and is supported by simulations. Extensions reproduce behavioral switching with S-shaped costs, edge effects from heterogeneous costs, and turn-taking when energy state dynamics are included.

Conclusion:
The curvature of individual vigilance costs determines whether groups distribute vigilance across many members or concentrate it in sentinels; habitat structure that creates flattening costs (vantage points) favors sentinels, while uniform habitats with steepening costs favor many-eyes.

Music:
Enjoy the music based on this article at the end of the episode.

Article title:
Many-eyes and sentinels in selfish and cooperative groups

First author:
Pilgrim C

Journal:
PNAS

DOI:
10.1073/pnas.2536017123

Reference:
Pilgrim C, Bate AM, Sigalou A, Aellen M, Morford J, Warren E, Krupenye C, Biro D, Mann RP. Many-eyes and sentinels in selfish and cooperative groups. PNAS. 2026;123(33):e2536017123. doi:10.1073/pnas.2536017123

License:
This episode is based on an open-access article published under the Creative Commons Attribution 4.0 International License (CC BY 4.0) – https://creativecommons.org/licenses/by/4.0/

Support:
Base by Base is independent and ad-free — no sponsors, no paywall. If an episode was worth your time, chip in and keep the papers audited and the original songs coming:
❤️ Support monthly: https://buy.stripe.com/cNifZhclVebvagk2JDgEg01
☕ One-time donation: https://donate.stripe.com/7sY4gz71B2sN3RWac5gEg00
More at basebybase.com

On PaperCast Base by Base you'll discover the latest in genomics, functional genomics, structural genomics, and proteomics.

Episode link: https://basebybase.com/episodes/many-eyes-or-sentinels-cost-curvature-vigilance

QC:
This episode was checked against the original article PDF and publication metadata for the episode release published on 2026-08-19.

QC Scope:
- article metadata and core scientific claims from the narration
- excludes analogies, intro/outro, and music
- transcript coverage: Audited the transcript sections describing the minimal model fi = b(S) − c(vi); S = ∑vi; cost-curvature (convex vs concave); environmental structure; selfish vs cooperative results; behavioral switching (sigmoidal costs); edge effects; turn-taking; energy-state dynamics; and discussed limitations.
- transcript topics: Model of collective vigilance (fi = b(S) − c(vi)); Cost curvature and environmental structure (convex vs concave); Selfish vs cooperative group outcomes; Behavioral switching with sigmoidal costs; Edge effects and spatial positioning; Energy-state dynamics and turn-taking

QC Summary:
- factual score: 10/10
- metadata score: 10/10
- supported core claims: 6
- claims flagged for review: 0
- metadata checks passed: 4
- metadata issues found: 0

Metadata Audited:
- article_doi
- article_title
- article_journal
- license

Factual Items Audited:
- fi = b(S) − c(vi) and S = ∑ vi
- b(S) is increasing and saturating; 0 ≤ b(S) ≤ r
- c(vi) is increasing with c(0) = 0; costs scale with vigilance
- Uniform habitats yield convex (steepening) costs; structured habitats with vantage points yield concave (flattening) costs
- The dichotomy (many-eyes under convex costs; sentinel under concave costs) holds for both selfish and cooperative groups
- Edge effects: peripheral individuals show higher vigilance due to geometry

QC result: Pass.

Feng P et al., PNAS - This paper describes a bipartite antisense oligonucleotide (5D‑ASO) design that appends a short 5′ splice site decoy tail to improve exon skipping, demonstrating robust efficacy for DMD exon 51 in cells, mice, and cynomolgus monkeys with a favorable safety profile. Key terms: antisense oligonucleotide, exon skipping, Duchenne muscular dystrophy, U1 snRNA decoy, dystrophin restoration.

Study Highlights:
The authors developed a bipartite ASO approach (5D‑ASO) that appends a short 5′ splice site–complementary tail to enhance exon skipping. An optimal 7–8 nt decoy appended to exon 51 ASOs markedly increased exon skipping in human cells and in multiple genetically modified mouse models, restoring dystrophin and improving muscle function. The lead MOE/PS 5D‑ASO showed durable tissue retention, dose‑dependent efficacy, and an overall favorable safety profile in mice and cynomolgus monkeys. The method was operative across multiple genes and exon targets, indicating broad applicability.

Conclusion:
Appending a short 5′ splice site decoy to exon‑targeting ASOs substantially increases exon‑skipping potency and therapeutic benefit in preclinical DMD models, supporting further clinical development of 5D‑ASO designs.

Music:
Enjoy the music based on this article at the end of the episode.

Article title:
An antisense method for efficient exon skipping and its application to Duchenne muscular dystrophy

First author:
Feng P

Journal:
PNAS

DOI:
10.1073/pnas.2606494123

Reference:
Feng P., Gao P., Meng S., Yuan Y., Krainer A.R., Hua Y. An antisense method for efficient exon skipping and its application to Duchenne muscular dystrophy. PNAS. 2026;123(33):e2606494123. doi:10.1073/pnas.2606494123

License:
This episode is based on an open-access article published under the Creative Commons Attribution 4.0 International License (CC BY 4.0) – https://creativecommons.org/licenses/by/4.0/

Support:
Base by Base is independent and ad-free — no sponsors, no paywall. If an episode was worth your time, chip in and keep the papers audited and the original songs coming:
❤️ Support monthly: https://buy.stripe.com/cNifZhclVebvagk2JDgEg01
☕ One-time donation: https://donate.stripe.com/7sY4gz71B2sN3RWac5gEg00
More at basebybase.com

On PaperCast Base by Base you'll discover the latest in genomics, functional genomics, structural genomics, and proteomics.

Episode link: https://basebybase.com/episodes/base-by-base-443-5d-aso-dmd

QC:
This episode was checked against the original article PDF and publication metadata for the episode release published on 2026-08-18.

QC Scope:
- article metadata and core scientific claims from the narration
- excludes analogies, intro/outro, and music
- transcript coverage: Audited the core narrative: Duchenne muscular dystrophy background; 5D-ASO design and 5′ splice site decoy tail mechanism; U1 snRNP decoy action; in vitro exon 51 skipping in RD cells; in vivo huEx51/huΔ52 mice data including dystrophin restoration; cynomolgus monkey efficacy/safety; off-target considerations; delivery
- transcript topics: DMD background and dystrophin function; 5D-ASO design and 5′ splice site decoy tail mechanism; U1 snRNP decoy mechanism and splicing repression; In vitro exon skipping in RD cells (Etep-L8c and MOE-Etep); In vivo exon 51 skipping in huEx51/huΔ52 mice and dystrophin restoration; Cynomolgus monkey exon 51 skipping and safety

QC Summary:
- factual score: 10/10
- metadata score: 10/10
- supported core claims: 6
- claims flagged for review: 0
- metadata checks passed: 4
- metadata issues found: 0

Metadata Audited:
- article_doi
- article_title
- article_journal
- license

Factual Items Audited:
- 5D-ASO tail acts as a decoy to misdirect U1 snRNP, increasing exon skipping
- An 8-nt tail appended to exon 51-targeting ASOs markedly boosts exon skipping across MOE/PS, PMO, and OMe chemistries
- 3 mg/kg 000A-L8c achieves comparable exon 51 skipping to 100 mg/kg MOE-Etep in huEx51/huΔ52 mice, ~30-fold potency increase
- Dystrophin restoration observed; dystroΔ117 transcript translated to dystrophin restoration in skeletal and cardiac muscles
- Cynomolgus monkeys show dose-dependent exon 51 skipping in diaphragm, quadriceps, and heart with favorable safety
- Off-target analyses indicate minimal global splicing disruption and no PCPA activation at therapeutic doses

QC result: Pass.

Rolseth AB et al., Proceedings of the National Academy of Sciences (PNAS) - This study links reduced Ca2+ entry through mutant TMC1 mechanotransducer channels to decreased PMCA2 pump density in outer hair cell stereocilia. PMCA2 turnover is rapid in the early postnatal period and is regulated by stereociliary Ca2+ via insertion from an apical vesicular pool; Neuroplastin (NPTN) later stabilizes the pump complex. Persistent pump reduction at hearing onset may contribute to hair cell mitochondrial dysfunction and death in Tmc1 mutants. Key terms: TMC1, PMCA2, hair cells, Ca2+ regulation, neuroplastin.

Study Highlights:
Tmc1 point mutations that reduce MET channel Ca2+ permeability show markedly decreased PMCA2 immunolabeling in outer hair cell bundles. PMCA2 density scaled with calculated Ca2+ entry, and experimental lowering of extracellular Ca2+ or pharmacological block of endocytosis or PtdIns(4,5)P2 synthesis reduced PMCA2 during the first postnatal week. PMCA2 is supplied from an apical vesicular pool, turns over rapidly before P11, and NPTN expression lags PMCA2 by ~2 days and less Ca2+ sensitivity, consistent with a stabilizing accessory role. The lower PMCA2 density persists at hearing onset and may contribute to mitochondrial dysfunction and subsequent hair cell death.

Conclusion:
Reduced stereociliary Ca2+ influx through mutant TMC1 channels decreases Ca2+-regulated insertion and rapid turnover of PMCA2 from an apical vesicular pool during early postnatal development. Because PMCA2 becomes less plastic after ~P11 and NPTN-mediated stabilization follows PMCA2 expression, early pump loss is maintained into hearing onset and may exacerbate intracellular Ca2+ dysregulation, mitochondrial impairment, and hair cell apoptosis in Tmc1 mutants.

Music:
Enjoy the music based on this article at the end of the episode.

Article title:
Ca2+ regulation of PMCA2 calcium pump expression in hair cells of Tmc1 deafness mutants

First author:
Rolseth AB

Journal:
Proceedings of the National Academy of Sciences (PNAS)

DOI:
10.1073/pnas.2607733123

Reference:
Rolseth AB, Beurg M, Konrad DE, Augusta BK, Fettiplace R. Ca2+ regulation of PMCA2 calcium pump expression in hair cells of Tmc1 deafness mutants. Proc Natl Acad Sci U.S.A. 2026;123:e2607733123. doi:10.1073/pnas.2607733123.

License:
This episode is based on an open-access article published under the Creative Commons Attribution 4.0 International License (CC BY 4.0) – https://creativecommons.org/licenses/by/4.0/

Support:
Base by Base is independent and ad-free — no sponsors, no paywall. If an episode was worth your time, chip in and keep the papers audited and the original songs coming:
❤️ Support monthly: https://buy.stripe.com/cNifZhclVebvagk2JDgEg01
☕ One-time donation: https://donate.stripe.com/7sY4gz71B2sN3RWac5gEg00
More at basebybase.com

On PaperCast Base by Base you'll discover the latest in genomics, functional genomics, structural genomics, and proteomics.

Episode link: https://basebybase.com/episodes/ca2-regulation-pmca2-tmc1

QC:
This episode was checked against the original article PDF and publication metadata for the episode release published on 2026-08-17.

QC Scope:
- article metadata and core scientific claims from the narration
- excludes analogies, intro/outro, and music
- transcript coverage: Audited the core scientific narrative in the transcript: MET Ca2+ permeability reductions in Tmc1 mutants, Ca2+-dependent PMCA2 regulation and vesicle trafficking, dynamic turnover and endocytosis, NPTN's stabilizing role, pharmacological perturbations (Pitstop2, PAO, GSK-1), endolymphatic potential effects at hearing
- transcript topics: MET channel Ca2+ permeability in Tmc1 mutants; PMCA2 density regulation and Ca2+ entry relationship; Ca2+-dependent PMCA2 turnover and vesicle trafficking; Neuroplastin (NPTN) role in PMCA2 stabilization; PI(4,5)P2 signaling, endocytosis, and PMCA2 regulation; Endolymphatic potential and Ca2+ toxicity in mature hearing

QC Summary:
- factual score: 10/10
- metadata score: 10/10
- supported core claims: 5
- claims flagged for review: 0
- metadata checks passed: 4
- metadata issues found: 0

Metadata Audited:
- article_doi
- article_title
- article_journal
- license

Factual Items Audited:
- TMC1 mutations reduce MET Ca2+ permeability and decrease PMCA2 density in outer hair cell stereocilia.
- PMCA2 density correlates linearly with MET channel Ca2+ entry.
- PMCA2 turnover is rapid before P11 and is inserted from an apical vesicular pool; Ca2+ regulates insertion.
- Endocytosis blockade (Pitstop2) markedly reduces PMCA2 density, indicating rapid vesicle turnover.
- NPTN expression parallels PMCA2 but lags by about 2 days and stabilizes PMCA2 in the membrane via a lipid-dependent mechanism.
- Lowering extracellular Ca2+ or blocking PtdIns(4,5)P2 synthesis reduces PMCA2, supporting Ca2+-dependent regulation.

QC result: Pass.

Tang X et al., PNAS - The authors apply an evolutionary sequence-covariation model to the Cav1.3 (CACNA1D) α1-subunit, map predicted pathogenicity onto structural models, and validate five predicted sites by patch-clamp electrophysiology and structural analysis. Predictions recapitulate known functional regions, reveal previously unrecognized clusters, and the tested variants produce diverse functional outcomes from nonconducting channels to gain- and loss-of-function gating changes. Key terms: Cav1.3, evolutionary modeling, CACNA1D, voltage-gated calcium channel, variant pathogenicity.

Study Highlights:
An evolutionary epistasis model predicted context-dependent conserved residues across Cav1.3 and recapitulated known functional sites. Mapping scores onto structural models highlighted novel clusters outside classical pore and voltage-sensor regions. Electrophysiological testing of five predicted variants confirmed diverse functional effects, including nonconducting (N745A), left-shifted activation (S635I, A376V, R1401A), and right-shifted or slowed gating (F1362A; Q1156E increased inactivation). The combined evolutionary, structural, and biophysical approach provides a scalable framework to prioritize and interpret CACNA1D variants.

Conclusion:
Evolutionary sequence-covariation combined with structural modeling and electrophysiology identifies novel functionally critical residues across Cav1.3 and enables rapid prioritization of pathogenic CACNA1D variants; the approach is generalizable to other ion channels but requires experimental follow-up to define gain- versus loss-of-function.

Music:
Enjoy the music based on this article at the end of the episode.

Article title:
Identification of novel functional sites in the Cav1.3 calcium channel α1-subunit using evolutionary modeling

First author:
Tang X

Journal:
PNAS

DOI:
10.1073/pnas.2602636123

Reference:
Tang X, Hermenean HC, Yakimchyka A, Tuluc P, Ortner NJ, Liedl KR. Identification of novel functional sites in the Cav1.3 calcium channel α1-subunit using evolutionary modeling. PNAS. 2026;123(32):e2602636123. doi:10.1073/pnas.2602636123

License:
This episode is based on an open-access article published under the Creative Commons Attribution 4.0 International License (CC BY 4.0) – https://creativecommons.org/licenses/by/4.0/

Support:
Base by Base is independent and ad-free — no sponsors, no paywall. If an episode was worth your time, chip in and keep the papers audited and the original songs coming:
❤️ Support monthly: https://buy.stripe.com/cNifZhclVebvagk2JDgEg01
☕ One-time donation: https://donate.stripe.com/7sY4gz71B2sN3RWac5gEg00
More at basebybase.com

On PaperCast Base by Base you'll discover the latest in genomics, functional genomics, structural genomics, and proteomics.

Episode link: https://basebybase.com/episodes/evolutionary-modeling-cav1-3-functional-sites

QC:
This episode was checked against the original article PDF and publication metadata for the episode release published on 2026-08-14.

QC Scope:
- article metadata and core scientific claims from the narration
- excludes analogies, intro/outro, and music
- transcript coverage: Audited the core scientific sections: evolutionary modeling predictions, structure mapping onto Cav1.3 models, electrophysiology validation in tsA-201 cells, and the functional effects of Cav1.3 variants (N745A, S635I, A376V, F1362A, R1401A, Q1156E); also reviewed limitations and clinical interpretation.
- transcript topics: Evolutionary sequence covariation and context-dependent conservation in Cav1.3; Mapping pathogenicity scores onto Cav1.3 cryo-EM structures; Electrophysiological validation of Cav1.3 variants in tsA-201 cells; Functional consequences of specific Cav1.3 variants (N745A, S635I, A376V, F1362A, R1401A, Q1156E); Limitations of heterologous expression systems and context-dependence; Clinical interpretation and generalization to other ion channels

QC Summary:
- factual score: 10/10
- metadata score: 10/10
- supported core claims: 5
- claims flagged for review: 0
- metadata checks passed: 4
- metadata issues found: 0

Metadata Audited:
- article_doi
- article_title
- article_journal
- license

Factual Items Audited:
- The article title is 'Identification of novel functional sites in the Cav1.3 calcium channel α1-subunit using evolutionary modeling'.
- The article is published in PNAS.
- DOI: 10.1073/pnas.2602636123.
- License: CC BY 4.0.
- Six Cav1.3 missense variants were tested experimentally: N745A, S635I, A376V, R1401A, F1362A, Q1156E.

QC result: Pass.

Lamkina EN et al., PNAS - This episode reviews a PNAS brief report showing that DENV-4 infection induces marked DNA damage in infected cells while broadly suppressing transcription of DNA repair pathways, with selective upregulation of a mutagenic translesion polymerase and suppressed ATR expression. The findings raise concerns about long-term molecular "scars" after dengue infection that could influence cancer and postdengue syndromes. Key terms: Dengue, DENV-4, DNA damage, DNA repair, Genome instability.

Study Highlights:
Using Vero E6 and HUH-7 cells infected at MOI 0.1 and followed up to 5 days, the authors detected a large increase in γH2AX signaling indicating DNA damage. A 96-gene qPCR panel showed widespread suppression of DNA repair and DDR transcripts across multiple pathways while mismatch repair proteins remained stable. ATR protein expression was reduced and the mutagenic polymerase POLι was upregulated, telomere length and TRF2 were unchanged, and LC3 I/II levels decreased. The authors propose these changes create durable molecular vulnerabilities that warrant patient-based validation.

Conclusion:
DENV-4 causes significant host DNA damage while repressing many DNA repair transcripts, a combination that may leave lasting molecular scars and elevate long-term disease risk, but confirmation in patient samples is needed.

Music:
Enjoy the music based on this article at the end of the episode.

Article title:
DENV-4 infection suppresses transcription of DNA repair genes

First author:
Lamkina EN

Journal:
PNAS

DOI:
10.1073/pnas.2536909123

Reference:
Lamkina EN, Reich J, Victora JA, et al. DENV-4 infection suppresses transcription of DNA repair genes. PNAS. 2026;123(32):e2536909123. doi:10.1073/pnas.2536909123

License:
This episode is based on an open-access article published under the Creative Commons Attribution 4.0 International License (CC BY 4.0) – https://creativecommons.org/licenses/by/4.0/

Support:
Base by Base is independent and ad-free — no sponsors, no paywall. If an episode was worth your time, chip in and keep the papers audited and the original songs coming:
❤️ Support monthly: https://buy.stripe.com/cNifZhclVebvagk2JDgEg01
☕ One-time donation: https://donate.stripe.com/7sY4gz71B2sN3RWac5gEg00
More at basebybase.com

On PaperCast Base by Base you'll discover the latest in genomics, functional genomics, structural genomics, and proteomics.

Episode link: https://basebybase.com/episodes/base-by-base-denv4-dna-repair

QC:
This episode was checked against the original article PDF and publication metadata for the episode release published on 2026-08-12.

QC Scope:
- article metadata and core scientific claims from the narration
- excludes analogies, intro/outro, and music
- transcript coverage: Audited the main scientific narrative: DENV-4 infection at MOI 0.1 in Vero E6 and HUH-7 cells; γH2AX DNA damage; broad suppression of DDR/DNA repair transcription with selective maintenance of MMR; ATR suppression; telomere length/TRF2 status; autophagy marker LC3 I/II; POLι upregulation; serotype-specific contrasts; a
- transcript topics: DENV-4 infection setup in vitro (MOI 0.1, 5 days, Vero E6 and HUH-7); γH2AX DNA damage signaling in infected cells; Broad suppression of DDR/DNA repair transcripts (BER, HR, NHEJ, NER) with MMR largely unchanged; ATR suppression and its consequence for DNA repair coordination; Telomere length and TRF2 status in infected cells; Maintenance of MMR proteins (MLH1, MSH2, MSH6) despite widespread suppression

QC Summary:
- factual score: 10/10
- metadata score: 10/10
- supported core claims: 6
- claims flagged for review: 0
- metadata checks passed: 4
- metadata issues found: 0

Metadata Audited:
- article_doi
- article_title
- article_journal
- license

Factual Items Audited:
- γH2AX increased up to 24-fold by 5 days post infection in surviving cells
- Broad suppression of DDR/DNA repair transcripts across BER, HR, NHEJ, NER with MMR largely unchanged
- ATR protein expression suppressed by day 5
- Telomere length unchanged and TRF2 protein expression unchanged
- MMR proteins MLH1, MSH2, MSH6 unchanged
- POLι upregulated (mutagenic translesion synthesis polymerase)

QC result: Pass.

Lamkina EN et al., PNAS - This episode reviews a PNAS brief report showing that DENV-4 infection induces marked DNA damage in infected cells while broadly suppressing transcription of DNA repair pathways, with selective upregulation of a mutagenic translesion polymerase and suppressed ATR expression. The findings raise concerns about long-term molecular "scars" after dengue infection that could influence cancer and postdengue syndromes. Key terms: Dengue, DENV-4, DNA damage, DNA repair, Genome instability.

Study Highlights:
Using Vero E6 and HUH-7 cells infected at MOI 0.1 and followed up to 5 days, the authors detected a large increase in γH2AX signaling indicating DNA damage. A 96-gene qPCR panel showed widespread suppression of DNA repair and DDR transcripts across multiple pathways while mismatch repair proteins remained stable. ATR protein expression was reduced and the mutagenic polymerase POLι was upregulated, telomere length and TRF2 were unchanged, and LC3 I/II levels decreased. The authors propose these changes create durable molecular vulnerabilities that warrant patient-based validation.

Conclusion:
DENV-4 causes significant host DNA damage while repressing many DNA repair transcripts, a combination that may leave lasting molecular scars and elevate long-term disease risk, but confirmation in patient samples is needed.

Music:
Enjoy the music based on this article at the end of the episode.

Article title:
DENV-4 infection suppresses transcription of DNA repair genes

First author:
Lamkina EN

Journal:
PNAS

DOI:
10.1073/pnas.2536909123

Reference:
Lamkina EN, Reich J, Victora JA, et al. DENV-4 infection suppresses transcription of DNA repair genes. PNAS. 2026;123(32):e2536909123. doi:10.1073/pnas.2536909123

License:
This episode is based on an open-access article published under the Creative Commons Attribution 4.0 International License (CC BY 4.0) – https://creativecommons.org/licenses/by/4.0/

Support:
Base by Base is independent and ad-free — no sponsors, no paywall. If an episode was worth your time, chip in and keep the papers audited and the original songs coming:
❤️ Support monthly: https://buy.stripe.com/cNifZhclVebvagk2JDgEg01
☕ One-time donation: https://donate.stripe.com/7sY4gz71B2sN3RWac5gEg00
More at basebybase.com

On PaperCast Base by Base you'll discover the latest in genomics, functional genomics, structural genomics, and proteomics.

Episode link: https://basebybase.com/episodes/base-by-base-denv4-dna-repair

QC:
This episode was checked against the original article PDF and publication metadata for the episode release published on 2026-08-12.

QC Scope:
- article metadata and core scientific claims from the narration
- excludes analogies, intro/outro, and music
- transcript coverage: Audited the main scientific narrative: DENV-4 infection at MOI 0.1 in Vero E6 and HUH-7 cells; γH2AX DNA damage; broad suppression of DDR/DNA repair transcription with selective maintenance of MMR; ATR suppression; telomere length/TRF2 status; autophagy marker LC3 I/II; POLι upregulation; serotype-specific contrasts; a
- transcript topics: DENV-4 infection setup in vitro (MOI 0.1, 5 days, Vero E6 and HUH-7); γH2AX DNA damage signaling in infected cells; Broad suppression of DDR/DNA repair transcripts (BER, HR, NHEJ, NER) with MMR largely unchanged; ATR suppression and its consequence for DNA repair coordination; Telomere length and TRF2 status in infected cells; Maintenance of MMR proteins (MLH1, MSH2, MSH6) despite widespread suppression

QC Summary:
- factual score: 10/10
- metadata score: 10/10
- supported core claims: 6
- claims flagged for review: 0
- metadata checks passed: 4
- metadata issues found: 0

Metadata Audited:
- article_doi
- article_title
- article_journal
- license

Factual Items Audited:
- γH2AX increased up to 24-fold by 5 days post infection in surviving cells
- Broad suppression of DDR/DNA repair transcripts across BER, HR, NHEJ, NER with MMR largely unchanged
- ATR protein expression suppressed by day 5
- Telomere length unchanged and TRF2 protein expression unchanged
- MMR proteins MLH1, MSH2, MSH6 unchanged
- POLι upregulated (mutagenic translesion synthesis polymerase)

QC result: Pass.

Longo LM et al., PNAS - This episode summarizes a PNAS study introducing CLSS, a contrastive two-tower protein language model that coembeds domain sequences, structures, and subsequences into a shared 32-dimensional latent space. Trained self-supervised on one million ECOD domains, CLSS aligns sequence and structure modalities, yields compact embeddings that recapitulate ECOD and CATH hierarchies, outperforms several state-of-the-art PLMs on ProteinShake classification tasks, and powers an interactive viewer for exploring protein space. Key terms: contrastive learning, protein sequence, protein structure, protein domains, protein embeddings.

Study Highlights:
The authors developed CLSS, a contrastive two-tower model that coembeds full domain sequences, structures, and sampled subsequences into a single latent space. CLSS embeddings recapitulate expert ECOD and CATH hierarchical labels despite never using those labels during training. A subsequence-trained variant (CLSS-sub) meaningfully embeds fragments, and CLSS outperforms comparison PLMs on downstream ProteinShake classification benchmarks. Visualizations of CLSS maps reveal a strong partitioning of domains by cofactor binding and other functional annotations.

Conclusion:
CLSS demonstrates that sequence and structure can be jointly organized into a compact, informative embedding space that captures domain hierarchy, subsequence reuse, and functional preferences; these embeddings enable efficient downstream classification, visualization, and potential applications in database search, alignment, protein design, and evolutionary analysis.

Music:
Enjoy the music based on this article at the end of the episode.

Article title:
Contrastive learning unites sequence and structure in a global representation of protein space

First author:
Longo LM

Journal:
PNAS

DOI:
10.1073/pnas.2532702123

Reference:
Longo LM, Yanai G, Axel G, Kolodny R, Ben-Tal N. Contrastive learning unites sequence and structure in a global representation of protein space. PNAS. 2026;123(32):e2532702123. doi:10.1073/pnas.2532702123.

License:
This episode is based on an open-access article published under the Creative Commons Attribution 4.0 International License (CC BY 4.0) – https://creativecommons.org/licenses/by/4.0/

Support:
Base by Base is independent and ad-free — no sponsors, no paywall. If an episode was worth your time, chip in and keep the papers audited and the original songs coming:
❤️ Support monthly: https://buy.stripe.com/cNifZhclVebvagk2JDgEg01
☕ One-time donation: https://donate.stripe.com/7sY4gz71B2sN3RWac5gEg00
More at basebybase.com

On PaperCast Base by Base you'll discover the latest in genomics, functional genomics, structural genomics, and proteomics.

Episode link: https://basebybase.com/episodes/clss-contrastive-sequence-structure-protein-space

QC:
This episode was checked against the original article PDF and publication metadata for the episode release published on 2026-08-11.

QC Scope:
- article metadata and core scientific claims from the narration
- excludes analogies, intro/outro, and music
- transcript coverage: Audited transcript portions describing CLSS concept and motivation, two-tower architecture, CLSS-sub subsequences, training on ECOD domains, evaluation on ProteinShake, TSNE visualizations, cofactor and zinc-binding patterns, and limitations.
- transcript topics: CLSS concept and motivation; Two-tower architecture: sequence tower (ESM2) and frozen structure encoder (ESM3); CLSS-sub subsequences (20-60 residues); Self-supervised training on ~1 million ECOD domains; Evaluation on ProteinShake and ECOD/CATH hierarchies; t-SNE visualizations showing coembedding of sequence and structure

QC Summary:
- factual score: 10/10
- metadata score: 10/10
- supported core claims: 8
- claims flagged for review: 0
- metadata checks passed: 4
- metadata issues found: 0

Metadata Audited:
- article_doi
- article_title
- article_journal
- license

Factual Items Audited:
- CLSS coembeds sequence and structure into a single 32-dimensional latent space
- Two-tower architecture: sequence tower initialized like ESM2 and a frozen ESM3 structure encoder
- CLSS-sub trains on random contiguous subsequences of length 20-60 residues
- Training data consists of ~1 million ECOD domains in a self-supervised setting
- CLSS-full overlaps sequence and structure embeddings on TSNE maps; other PLMs show separation
- CLSS outperforms state-of-the-art PLMs (ESM3, ProstT5, ProTrek) on ProteinShake SCOP-label tasks

QC result: Pass.

Axakova A et al., The American Journal of Human Genetics - Axakova et al. generated a variant effect map for AIRE using an insulin‑promoter GFP reporter in HEK293 cells to measure the functional impact of 9,790 missense substitutions and provide calibrated evidence for clinical variant interpretation. Key terms: AIRE, missense variants, variant effect map, APS-1, functional assay.

Study Highlights:
The authors used an insulin‑promoter‑driven GFP reporter in HEK293 cells and a DT‑POPCode mutagenesis library to assay 9,790 AIRE missense variants. The resulting map recapitulated known functional regions (CARD, SAND, PHD2, C‑terminal), revealed both loss‑ and gain‑of‑function changes, and exposed a blind spot for PHD1 in this assay. Benchmarking against ClinVar and computational predictors enabled calibrated evidence for 70% of ClinVar VUSs and supported reclassification of 32% (109/345) of VUSs. The map also correlated quantitatively with APS‑1 severity in an international cohort and associated damaging variants with hypoparathyroidism and vitamin B12 deficiency anemia in UK Biobank.

Conclusion:
This proactive, calibrated AIRE variant effect map provides immediate functional evidence to improve missense variant classification and expedite APS‑1 diagnosis, while highlighting assay limitations (PHD1 blind spot, cDNA-based design) that warrant follow-up studies.

Music:
Enjoy the music based on this article at the end of the episode.

Article title:
Systematic and proactive evaluation of AIRE missense variant effects

First author:
Axakova A

Journal:
The American Journal of Human Genetics

DOI:
10.1016/j.ajhg.2026.07.008

Reference:
Axakova A., Berger A.H., van Loggerenberg W., et al. Systematic and proactive evaluation of AIRE missense variant effects. The American Journal of Human Genetics 113, 1–21 (2026). https://doi.org/10.1016/j.ajhg.2026.07.008

License:
This episode is based on an open-access article published under the Creative Commons Attribution 4.0 International License (CC BY 4.0) – https://creativecommons.org/licenses/by/4.0/

Support:
Base by Base is independent and ad-free — no sponsors, no paywall. If an episode was worth your time, chip in and keep the papers audited and the original songs coming:
❤️ Support monthly: https://buy.stripe.com/cNifZhclVebvagk2JDgEg01
☕ One-time donation: https://donate.stripe.com/7sY4gz71B2sN3RWac5gEg00
More at basebybase.com

On PaperCast Base by Base you'll discover the latest in genomics, functional genomics, structural genomics, and proteomics.

Episode link: https://basebybase.com/episodes/s2-e438-aire-variant-effect-map

QC:
This episode was checked against the original article PDF and publication metadata for the episode release published on 2026-08-10.

QC Scope:
- article metadata and core scientific claims from the narration
- excludes analogies, intro/outro, and music
- transcript coverage: Substantively audited the sections describing the AIRE variant-effect map, high-throughput mutagenesis and screening, structural-domain interpretation (CARD/SAND/PHD1/PHD2), gain-of-function findings, CAM-score genotype-phenotype correlations, and population-level associations (APS-1 cohort and UK Biobank). Also review
- transcript topics: AIRE and APS-1 background; Insulin promoter GFP reporter assay in HEK293 cells; DT-POPCode library and missense variant generation; Variant effect map results and validation; Structural-domain mapping (CARD, SAND, PHD1, PHD2, C-terminal); Gain-of-function variants and disordered regions

QC Summary:
- factual score: 10/10
- metadata score: 10/10
- supported core claims: 7
- claims flagged for review: 0
- metadata checks passed: 4
- metadata issues found: 0

Metadata Audited:
- article_doi
- article_title
- article_journal
- license

Factual Items Audited:
- Variant effect map covers 9,790 AIRE missense variants (~90% of possible substitutions).
- 3,127 SNV-accessible substitutions (98% of 3,189 SNV-possible substitutions).
- Insulin promoter–GFP reporter in HEK293 cells used for functional readout.
- PHD1 domain shows a blind spot in this open-chromatin reporter context.
- Eight variants significantly upregulated the reporter (gain-of-function).
- Pro126 and Pro129 intolerant to substitutions near the nuclear localization signal.

QC result: Pass.

Hanson C et al., The American Journal of Human Genetics - Hanson et al. combine pooled multi-donor human neural progenitor cell "villages" with Townlet, a hierarchical Dirichlet regression model, to estimate donor-specific proliferation and treatment responses from Census-seq. They identify 16p11.2 deletion–associated NPC hyperproliferation and nominate common variants near ZFHX3 for proliferation and an ARNT2-linked locus for lead (Pb) sensitivity. Key terms: cell villages, Dirichlet regression, neural progenitor cells, 16p11.2 deletion, lead (Pb) sensitivity.

Study Highlights:
The authors developed and validated cell villages of 12–39 donor-derived NPC lines and Townlet, a Dirichlet regression framework, to analyze compositional time-series Census-seq data and estimate donor proliferation and treatment effects. Using this system they detected hyperproliferation of NPCs carrying the 16p11.2 deletion, mapped a common variant near ZFHX3 associated with proliferation, and identified ARNT2-linked variants associated with differential sensitivity to lead. Villages preserved donor-intrinsic growth rates while reducing technical variation, and Townlet outperformed standard models in simulations and empirical benchmarks.

Conclusion:
Pooled multi-donor NPC villages combined with the Townlet Dirichlet model provide a scalable, reproducible platform to map genetic and gene–environment effects on human cell fitness, nominating 16p11.2, ZFHX3, and ARNT2 as contributors to NPC proliferation and Pb sensitivity.

Music:
Enjoy the music based on this article at the end of the episode.

Article title:
Cell villages and Dirichlet modeling map human cell fitness genetics

First author:
Hanson C

Journal:
The American Journal of Human Genetics

DOI:
10.1016/j.ajhg.2026.07.005

Reference:
Hanson C., Derebenskiy T., Rodriguez Vega A., et al. Cell villages and Dirichlet modeling map human cell fitness genetics. The American Journal of Human Genetics. 2026;113:1–21. doi:10.1016/j.ajhg.2026.07.005

License:
This episode is based on an open-access article published under the Creative Commons Attribution 4.0 International License (CC BY 4.0) – https://creativecommons.org/licenses/by/4.0/

Support:
Base by Base is independent and ad-free — no sponsors, no paywall. If an episode was worth your time, chip in and keep the papers audited and the original songs coming:
❤️ Support monthly: https://buy.stripe.com/cNifZhclVebvagk2JDgEg01
☕ One-time donation: https://donate.stripe.com/7sY4gz71B2sN3RWac5gEg00
More at basebybase.com

On PaperCast Base by Base you'll discover the latest in genomics, functional genomics, structural genomics, and proteomics.

Episode link: https://basebybase.com/episodes/cell-villages-dirichlet-modeling-human-cell-fitness

QC:
This episode was checked against the original article PDF and publication metadata for the episode release published on 2026-08-09.

QC Scope:
- article metadata and core scientific claims from the narration
- excludes analogies, intro/outro, and music
- transcript coverage: Audited the transcript sections describing Townlet and cell villages, validation against array cultures, 16p11.2 deletion hyperproliferation, GWAS identifying ZFHX3-associated proliferation variants, and lead (Pb) resistance modifiers linked to ARNT2; also reviewed environmental exposome implications and limitations di
- transcript topics: Cell villages concept and Townlet model; Census-seq and compositional data challenges; Village vs array validation and donor-intrinsic proliferation; 16p11.2 deletion NPC hyperproliferation in villages; GWAS in villages identifying ZFHX3 locus and rs34470044; Lead (Pb) exposure and ARNT2-associated Pb resistance

QC Summary:
- factual score: 10/10
- metadata score: 10/10
- supported core claims: 4
- claims flagged for review: 0
- metadata checks passed: 4
- metadata issues found: 0

Metadata Audited:
- article_doi
- article_title
- article_journal
- license

Factual Items Audited:
- Townlet is a hierarchical Dirichlet regression model for analyzing proportional data from cell villages.
- Cell villages reduce technical variation and preserve donor-intrinsic proliferation rates compared with arrayed cultures.
- A 16p11.2 deletion NPC village shows hyperproliferation relative to controls.
- A GWAS in a 35-donor proliferation village identified a lead variant near ZFHX3 (rs34470044) explaining about 49.7% of inter-donor variation in NPC proliferation.
- A lead Pb-resistance locus near ARNT2 (rs3833030/rs3858973) explains about 55.2% of between-donor variation in Pb vulnerability.
- Townlet demonstrates higher sensitivity and power than standard models (EGE/LM/Dirichlet) in simulations.

QC result: Pass.