This remarkable discovery, published in Science, sheds light not only on the versatile evolution of protein machinery but also on the emergence of multicellularity—a pivotal milestone in life’s complexity. Lead researcher Benjamin Springstein and his colleagues focused their investigations on Anabaena sp. PCC 7120, a model multicellular cyanobacterium that has captivated researchers for over three decades due to its ecological significance and cellular intricacy.

At the heart of cellular life lies the accurate replication and distribution of genetic material. In bacteria, DNA is tightly packed within chromosomes and plasmids, both essential for replication fidelity and cellular function. Chromosomes carry vital genes necessary for survival, while plasmids often harbor accessory genes that may provide adaptive advantages. Classically, bacterial DNA segregation systems, such as the ParMR complex, are known to function exclusively on plasmids, ensuring their precise inheritance during cell division.

Springstein’s team made a startling observation: in Anabaena and certain other multicellular cyanobacteria, the ParMR system appeared encoded on the chromosome rather than on plasmids—a fundamental deviation from prior understanding. Initially hypothesizing a role in chromosome segregation, subsequent experimental exploration took a surprising turn. Instead of interacting with DNA as expected, the ParR component was found to associate with the inner cell membrane. ParM filaments deviated from their canonical organization by forming bipolar, membrane-associated arrays akin to a cytoskeletal cortex rather than spindle-like structures that physically segregate DNA.

This unexpected functional repurposing transforms the classical ParMR DNA segregation machinery into a novel cytoskeletal system, which the researchers have aptly renamed CorMR. Detailed in-vitro reconstitution experiments revealed the dynamic behavior of these filaments: they exhibited instability characterized by phases of elongation followed by rapid disassembly, mirroring behaviors observed in eukaryotic microtubules—a finding highlighting convergent mechanical principles across domains of life.

To elucidate the structural underpinnings of these unique filaments, the ISTA team collaborated with the Schur group, leveraging cryo-electron microscopy to capture high-resolution architectures of the CorMR filaments. Their observations confirmed a bipolar filament configuration granting growth and shrinkage at both ends — a distinct departure from the polar filament formation typical in plasmid segregation systems. This structural adaptation is likely critical for the filaments’ role in maintaining cellular morphology.

The biological significance of this system became evident when Anabaena cells lacking CorMR filaments displayed profound morphological abnormalities. Normally rectangular and elongated cells shifted toward a more rounded, swollen phenotype—a hallmark of compromised structural integrity. These defects parallel those observed in other bacteria when cell-shape determinant genes are disrupted, underscoring that the CorMR system fundamentally orchestrates cell architecture instead of DNA segregation in these cyanobacteria.

How such a transformation in function arose during evolution was itself a focus of investigation. Bioinformatic analyses conducted by collaborators illuminated a gradual, stepwise process underpinning CorMR’s evolution. Initially a plasmid-encoded system, ParMR transitioned its genomic locus onto the chromosome. This shift was accompanied by alterations in protein size and conformation, acquisition of lipid membrane-binding properties, and integration into regulatory networks governed by additional protein assemblies. Collectively, these evolutionary refinements repurposed an ancient DNA segregation machine into a sophisticated cytoskeletal scaffold critical for cell shape—a testament to the plasticity of molecular systems within living cells.

This discovery broadens our understanding of cytoskeletal diversity beyond the well-characterized eukaryotic systems, revealing how bacteria employ analogous yet distinct strategies for cellular organization and morphology control. It also suggests that bacterial cytoskeletal components may have independently evolved or been repurposed multiple times to fulfill novel structural roles. Given the ecological and evolutionary significance of cyanobacteria, insights into their cellular machinery could illuminate broader principles of bacterial multicellularity and adaptation.

Springstein remarked that the evolutionary ingenuity demonstrated by these bacteria challenges long-held dogmas about the exclusivity and functions of molecular segregation systems. The CorMR system exemplifies how proteins originally dedicated to one cellular task can be co-opted and refined for entirely new functions, thus fueling the diversification of cellular form and function that underpins biological complexity.

Beyond basic science, understanding the mechanistic basis and evolution of bacterial cytoskeletal systems holds potential for biotechnological and synthetic biology applications. Engineering such systems could pave the way for designing microbial factories with tailored morphologies, enhancing stability, and optimizing metabolic efficiencies.

As research on Anabaena and its kin progresses, questions arise about how widespread similar repurposings are across bacterial lineages and what evolutionary pressures drive such adaptations. The CorMR system opens a new frontier in the study of microbial cell biology, revealing ancient functional transitions with ripple effects that extend into ecology, evolution, and applied sciences.

Subject of Research: Cells

Article Title: Repurposing of a DNA segregation machinery into a cytoskeletal system controlling cell shape

News Publication Date: 16-Apr-2026

Web References: https://doi.org/10.1126/science.aea6343

Image Credits: © Loose group | ISTA

Keywords

Cyanobacteria, Evolution, DNA, Bacterial DNA, Bacteria

The essence of this research lies in the revelation that glaciers react dynamically to rising atmospheric temperatures by increasing heat exchange at their surfaces, effectively cooling the adjacent air. Shaw’s memorable experience atop the Glacier de Corbassière in the Swiss Alps during the mild summer of 2022 underscores the paradoxical nature of glacier climates. Although global atmospheric temperatures have climbed steadily for decades, these glaciers maintain cooler near-surface temperatures, creating microclimates that temporarily resist broader trends of warming. In some cases, such as the vast Himalayan glaciers, this phenomenon manifests as powerful cold katabatic winds that flow downhill, cooling local environments and forestalling immediate ecological damage.

Underneath this surface cooling lies a balance of immense complexity. The ice masses, by virtue of their size and thermal properties, absorb the impact of increasing ambient temperatures and translate this energy into the generation of cold air currents. These katabatic winds, born from the gravitational flow of dense, chilled air down glacier slopes, have profound effects on local weather patterns and ecosystem stability. However, the durability of this glacier-led cooling effect is inherently finite. The researchers’ meticulous compilation and statistical modeling from disparate glacier climates—350 weather stations across 62 glaciers worldwide—demonstrates that this decoupling from ambient temperature gain is neither indefinite nor uniform.

The concept of “decoupling” introduced by Shaw refers to the divergence between rapidly warming atmospheric temperatures and relatively cooler glacier surface temperatures. Their findings quantify this relationship: for every degree increase in ambient temperature, glacier near-surface temperatures increase by only about 0.83 degrees Celsius on average, indicating a tempered warming effect. Yet, as glaciers thin and recede, particularly those burdened with debris mantles which affect heat transfer dynamics, these decoupled microclimates weaken. The glaciers’ protective self-cooling mechanism, which has granted some respite from the immediacy of warming, will soon falter.

Modeling future scenarios sheds light on a critical timeline. The self-cooling effect of glaciers is projected to reach its zenith between the 2020s and 2040s, a narrow window during which glacier cooling counteracts warming trends most effectively. Beyond this temporal boundary, however, the continued mass loss and fragmentation of glaciers will disrupt their ability to sustain these microclimates. The consequences are dire: as glaciers “recouple” to the warming atmosphere, their surface temperatures will climb sharply, accelerating melting rates and threatening to unleash a cascade of ecological, hydrological, and climatological impacts worldwide.

This research also highlights the formidable challenges inherent in studying glacier-climate interactions on a global scale. The scarcity of continuous, long-term data from remote glacier sites often impedes the refinement of climate models. Shaw and his colleagues overcame these hurdles by aggregating an unprecedented dataset, which combines published and unpublished measurements from multiple global research projects. This extensive data pooling enabled the development of a robust statistical framework capable of capturing the nuanced physical processes governing glacier cooling and predicting their evolution under a warming climate.

The implications of these findings extend beyond academic intrigue. The fact that glaciers can still cool their local environments for a limited timeframe offers a narrow window to refine water resource management globally. Freshwater stored in glaciers is critical for billions, feeding rivers and agriculture downstream. Understanding that this self-cooling delay will soon lapse underscores the urgency of leveraging this time to optimize water policy, infrastructure, and conservation efforts—efforts that may provide communities a buffer against imminent hydrological changes induced by glacier loss.

Yet, Shaw and the ISTA team caution against false hopes or misguided interventions such as geo-engineering. Proposals to artificially seed clouds or blanket glaciers represent expensive, short-term fixes that ignore the underlying climate realities. Instead, they advocate for acceptance of the unavoidable long-term glacier decline and for concerted efforts aimed at mitigating climate change itself through aggressive reduction of greenhouse gas emissions. The science is clear: without decisive action, glaciers’ natural defense mechanisms will be overwhelmed, with wide-ranging implications for global climate systems, sea-level rise, and biodiversity.

The research also serves as a clarion call for heightened public awareness and coordinated global policy responses. “Every fraction of a degree matters,” Shaw emphasizes, echoing a mantra long championed by climate scientists. The temporal window during which glaciers cool their surfaces offers a limited but valuable opportunity for society to act decisively. Failure to curtail warming could render this precious time moot, locking in irreversible damage to mountain ecosystems and the invaluable freshwater reserves they sustain.

As glaciers recouple with the atmosphere and lose their cooling ability, the resulting feedback loops will likely accelerate climate-driven changes beyond the glacial environment itself. This includes altered weather patterns, exacerbated droughts, and intensified flooding downstream, magnifying both environmental and socio-economic vulnerabilities. The forthcoming decades will thus be crucial in determining not only the fate of glaciers but also the broader resilience of human and ecological systems in a warming world.

In essence, the ISTA-led study reframes glaciers not merely as passive victims of climate change but as active, albeit temporary, agents capable of modulating their microclimate through self-cooling mechanisms. The narrow window of peak glacier cooling identified by the research symbolizes a fleeting resistance before an anticipated acceleration of warming impacts sets in. This nuanced understanding enhances our predictive capabilities and refines the urgency with which climate action must be pursued. The invisible battleground of glacier self-cooling serves as a potent reminder of nature’s resilience and its limits in facing an anthropogenically altered climate.

This scientific advancement underscores the profound integration of high-altitude field data, sophisticated computational models, and international collaboration, illustrating the frontier of climate-glacial interactions study. The detailed insights gained not only deepen our comprehension of glacier dynamics but also cast a stark light on the future trajectories of these majestic natural formations. Whether humanity rises to this challenge will shape the environmental and societal legacy of the 21st century.

Subject of Research: Not applicable
Article Title: Mountain Glaciers will Recouple to Atmospheric Warming Over the 21st Century
News Publication Date: 10-Oct-2025
Web References: http://dx.doi.org/10.1038/s41558-025-02449-0
References: Shaw, T., Pellicciotti, F., et al. (2025). Mountain Glaciers will Recouple to Atmospheric Warming Over the 21st Century. Nature Climate Change. DOI: 10.1038/s41558-025-02449-0
Image Credits: © Thomas Shaw | ISTA
Keywords: Glaciers, Glaciology, Glacial termination, Hydrology, Climatology, Climate change mitigation, Climate change, Modeling, Environmental impact assessments