The genomic identity of early smallpox in South America

Ancient DNA extracted from two Inca-Colonial individuals buried in northern Chile has yielded the first smallpox genomes recovered from the Americas, dated to roughly 1492–1631 CE. These viral sequences represent a previously unknown, now-extinct lineage that branched off around 1296 CE — after early medieval European strains diverged but before modern variola variants arose — providing direct molecular confirmation that smallpox reached the Americas through European colonization. Beyond establishing the virus's origin, the study traces its evolutionary trajectory: gene inactivation proceeded at a steady rate until the late sixteenth century, then slowed under apparent selective constraint before substitution rates rebounded. The researchers link these shifts to large-scale changes in human population size and disease dynamics. The findings fill a critical gap in understanding how smallpox devastated Indigenous American populations and clarify where colonial-era strains fit within the broader evolutionary history of variola virus.

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Spatiotemporal multiomics uncover tumor ecosystem dynamics during metastatic colonization

Researchers investigated how cancer cells establish metastatic colonies in distant tissues, focusing on the poorly understood interplay between disseminated tumor cells (DTCs) and their local microenvironment. Using combined single-cell and spatial profiling across liver cancer mouse models and human metastatic samples, they tracked cellular dynamics from the earliest stages of seeding through to overt lung metastasis.

They discovered a subpopulation of quiescent DTCs with high PHGDH expression that evades initial immune attack and accumulates in early micrometastases. These cells suppress immune recruitment by using PHGDH-driven epigenetic silencing — via H3K27me3 modification — to shut down chemokine production. Concurrently, a specific macrophage subset creates an immune-privileged niche that facilitates tumor expansion. Disrupting either the PHGDH-H3K27me3 pathway in DTCs or eliminating these macrophages restored immune surveillance and blocked metastatic growth. The findings point toward potential therapeutic strategies aimed at eliminating micrometastases before they develop into overt disease.

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Ancient DNA shows how smallpox got to the Americas

Before European colonization, smallpox was absent from the Americas. Ancient DNA analysis of historical remains has now provided direct evidence that the disease arrived with European contact, settling a long-standing debate about whether variola virus existed in the New World prior to colonization. The findings clarify the catastrophic timing of smallpox's introduction to Indigenous populations, who had no prior immunity, and help explain the devastating mortality that followed European arrival. By examining genetic material from ancient samples, researchers could trace the virus's origins and spread, offering a clearer picture of one of history's most consequential biological encounters. The work underscores how ancient DNA techniques can resolve questions about infectious disease history that written records alone cannot answer.

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X-chromosome inactivation draws L1 mutagenesis to the human X chromosome

Researchers investigated why the human X chromosome is unusually packed with LINE-1 (L1) retrotransposons, testing whether X-chromosome inactivation (XCI) might itself drive this accumulation. Using long-read DNA sequencing with a haplotype-aware approach in PA-1 embryonic carcinoma cells — which undergo clonal XCI, allowing the active (Xa) and inactive (Xi) X chromosomes to be distinguished — they tracked where engineered L1 elements preferentially inserted. L1 integrations were strongly biased toward the Xi and toward genomic regions that replicate late during S-phase more broadly. This reverses the traditional causal assumption: rather than L1s being pre-positioned to help silence the X, XCI appears to have drawn L1 insertions to the X over evolutionary time. A notable implication is that this insertion bias in XX individuals could effectively double the rate of heritable, disease-causing X-linked L1 mutations passed to XY offspring.

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Beyond the scales: Marine archaeogenomics for the conservation and restoration of fisheries

Fisheries management has long suffered from shifting baseline syndrome — setting conservation targets against ecosystems already degraded by centuries of human exploitation. This review examines how archaeogenomics, combining ancient DNA extracted from archaeological fish remains with whole-genome sequencing, can reveal what marine ecosystems and fish populations looked like before modern industrial pressures. Recent technical advances in both laboratory methods and computational analysis have made it possible to reconstruct historical fish population sizes, migration routes, past trade networks, and how species responded to environmental change over long timescales. Focusing particularly on whole-genome studies published between 2020 and 2025, the authors synthesize what this growing field has uncovered about historical fisheries and marine ecosystem dynamics. The core argument is that these deep historical baselines should directly inform more realistic restoration goals, conservation policy, sustainable fisheries management, and strategies for helping marine species adapt to ongoing climate change.

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