Invisible actors in groundwater

Researchers from the Cluster of Excellence »Balance of the Microverse« at the University of Jena (Germany) discover previously unknown viruses and their central role in ecosystems

Friedrich-Schiller-Universitaet Jena

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Water sampling well in the Hainich.

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Credit: Akbar Adjie Pratama

More than 257,000 Viruses Discovered – Almost All New

The researchers analyzed large quantities of environmental genomic data (1.24 terabases) from seven groundwater wells at the Hainich Critical Zone Exploratory in Thuringia. The team identified over 257,000 viral operational taxonomic units, i.e. viruses at species level, 99 % of which were previously unknown.

Viruses Affect the Function of Their Microbial Hosts

The research team was particularly surprised to find that numerous viruses carrying so-called auxiliary metabolic genes (AMGs) were among the viruses detected. These AMGs allow viruses to reprogram host metabolism, directly influencing carbon, nitrogen, and sulfur cycling, processes central to ecosystem-level biogeochemical fluxes. Akbar Adjie Pratama (first author of the study) notes: »The occurrence and functional diversity of viral AMGs provide a baseline for investigating how viruses influence microbial community dynamics, metabolic reprogramming, and nutrient cycling in groundwater.«

Based on the widespread occurrence of AMGs, the researchers conclude that viruses play a role in modulating the metabolism of their microbial hosts. Although these conclusions are based on genomic data rather than experimental evidence, the results suggest that viruses have a significant impact on the groundwater microbiome.

New Perspectives on Complex Interactions

The data suggest that viruses do not only affect individual microbes, but also are integrated into complex microbial networks. Viruses could simultaneously control ultra-small organisms and their hosts—a mechanism previously only known from extreme habitats, such as acid mine drainage systems, hypersaline lakes, and hydrothermal ecosystems. By studying this groundwater system, while we often think of viruses infecting a single host, in groundwater it appears much more complicated than that. For example, viruses that infected the ultra-small microbes appear to be involved in a ménage à trois where three entities are infection impacted. The discovery of these multi-layer interactions expands the understanding of the groundwater microbiome and highlights the complex interconnectedness of these life communities. Furthermore, this study is hypothesis-generating, providing a foundation for future targeted experiments and studies.

Prof. Dr. Matthew B. Sullivan (co-corresponding author of the study) explains the significance of this finding: »Understanding viral roles in these systems is essential for predicting how groundwater ecosystems will react to environmental changes.«

»Our results show that viruses are not passive bystanders, but active players that influence key functions of the groundwater microbiome,« explains Prof. Dr. Kirsten Küsel, spokesperson for the Cluster.

Significance for the Environment and Water Management

The results also have practical relevance: understanding viral control over nutrient cycles provides the necessary indicators for modelling ecosystem responses. In future, changes in viral nutrient turnover can be used to predict how groundwater systems will respond to climate change, falling water levels or nutrient inputs. Furthermore, the knowledge about AMGs provides more precise models for global subsurface biogeochemical cycles and opens up potential for biotechnological applications.

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Journal

Nature Communications

DOI

10.1038/s41467-026-68914-2 

Method of Research

Experimental study

Subject of Research

Cells

Article Title

Diversity and ecological roles of hidden viral players in groundwater microbiomes

 

Malaria: Newly identified “crown” stage controls parasite reproduction

The Hebrew University of Jerusalem

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Research Team

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Credit: Tomer Shamay

Researchers studying the malaria parasite Plasmodium falciparum have discovered a previously unknown stage in its life cycle that appears to be crucial for reproduction. This is important because malaria depends on the parasite’s rapid ability to multiply inside the human body, so stopping its reproduction could help prevent severe disease and save lives. Using a new live-imaging method, the team found that before the parasite can divide, a key structure inside the cell must reshape into a “Crown” form and connect to the cell’s nucleus. This step helps ensure that essential parts of the parasite are properly passed on to its new daughter cells. The findings point to a promising new target for future malaria treatments: interrupting the signals that control this “Crown” stage could potentially stop the parasite from multiplying.

A new study has uncovered a hidden step that helps the deadliest malaria parasite survive and multiply inside the human body. Researchers studying Plasmodium falciparum found that the parasite relies on a brief but essential stage, nicknamed the “Crown” stage, to make sure a crucial internal structure is passed on correctly when it divides. The discovery offers a fresh look at how the parasite reproduces and could point to new ways to stop malaria by disrupting this process.

Malaria remains one of the world’s most devastating infectious diseases, causing hundreds of thousands of deaths each year, most of them among young children in sub-Saharan Africa.

The research, published in the Journal of Cell Biology, was led by Dr. Anat Florentin of The Kuvin Center for the Study of Infectious and Tropical Diseases and the Department of Microbiology and Molecular Genetics in the Faculty of Medicine at Hebrew University. The team focused on a tiny structure inside the parasite called the apicoplast. While humans don’t have this organelle, malaria parasites depend on it to survive. Although the apicoplast originally came from a photosynthetic ancestor, it now functions as a kind of mini chemical factory, producing essential molecules, including fatty acids and isoprenoids, that the parasite needs to grow inside human red blood cells.

“By tracking both DNA replication and apicoplast development in real time, we found the details of these events and what controls them,” says Dr. Florentin. “There are both signals from the nucleus and intrinsic organelle cues at play. These mechanisms could provide a new opportunity for drug development: if, for example, we can interrupt the communication between the nucleus and the apicoplast, we will stop the parasite from multiplying.”

To observe what happens inside the parasite as it grows, the researchers developed an advanced live-imaging system that follows subcellular structures in high resolution across the parasite’s full 48-hour life cycle. Using this approach, they identified four stages in apicoplast development: Elongation, Branching, Crown, and Division.

The study highlights the importance of the Crown stage, a short one-hour period just before the parasite divides. During this phase, the apicoplast stretches across multiple nuclei and attaches to structures known as centriolar plaques, the parasite’s equivalent of the machinery that helps cells organize division. This connection acts like a distribution checkpoint, helping ensure that when the parasite splits, every new daughter cell receives one complete, working apicoplast.

To understand how this process is controlled, the researchers used drugs that block specific steps in the parasite’s replication:

• Blocking nuclear DNA replication: When the researchers stopped the parasite from copying its nuclear DNA using aphidicolin, apicoplast development stalled almost immediately. This showed that the apicoplast cannot grow properly unless the parasite has entered the DNA-copying phase of its cycle.
• Blocking apicoplast DNA replication: In contrast, when the team blocked the apicoplast’s own DNA replication using ciprofloxacin (CIP), the organelle still grew and formed branches but it failed to form the Crown structure.

Without the Crown stage, the apicoplast could not attach to the centriolar plaques, and daughter cells were produced without it. This leads to a phenomenon known as “delayed death.” The first generation of parasites may survive, but the next generation cannot, because without the apicoplast, the parasite is missing a structure it needs to make essential molecules and stay alive.

Overall, the findings challenge the idea that the apicoplast functions independently inside the parasite. Instead, the study suggests that the apicoplast’s development and inheritance depend on carefully timed signals from the parasite’s nucleus, especially during the newly identified Crown stage.

According to the researchers, this newly uncovered dependency may represent a promising vulnerability. By targeting the signaling mechanisms that coordinate the parasite’s DNA replication and apicoplast development, future therapies could disrupt parasite reproduction and help stop malaria by preventing the parasite from multiplying in the first place.

Coordination between organelles in the Plasmodium cell facilitates its unique cell division. The multiple nuclei (red), are connected to the apicoplast (green) by centriolar plaques (pink). This interaction happens only during the “Crown” stage and it is critical to from multiple daughter cells, each with a complete set of organelles. This image was prepared using a technique called expansion microscopy and visualized by a Confocal microscope.

A Plasmodium parasite engulfed within a red blood cell showing its nuclei (turquoise) and the apicoplast (magenta). Total protein labelling outlines the boundaries of the parasite and the host red blood cell. Coordinated alignment of the apicoplast with dividing nuclei is critical for organelle inheritance and malaria parasite reproduction. This image was prepared using a technique called expansion microscopy and visualized by a Confocal microscope.

Credit

Michal Shahar

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Journal

Journal of Cell Biology

DOI

10.1083/jcb.202504052 

Method of Research

Experimental study

Subject of Research

Cells

Article Title

Independent nuclear and organellar mechanisms determine apicoplast fate in malaria parasites

 

Norwegian prime minister Støre Presents the Mohn Prize to Canadian researcher

Professor John P. Smol was today given the Mohn Prize by Prime Minister Jonas Gahr Støre. "You are a true leader and an important contributor," said the Prime Minister to the prize winner.

UiT The Arctic University of Norway

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Price winner John Smol (centre) sorrounded by Prime Minister Jonas Gahr Støre (left) and Rector Dag Rune Olsen (right).

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Credit: David Jensen / Arctic Frontiers

John P. Smol, a professor at Queen's University in Canada, received the prize for his role in identifying the factors driving environmental changes in the Arctic. The international Mohn Prize is awarded every two years for outstanding research related to the Arctic. 

 "Professor Smol’s career illustrates the role that science can and should play: solving global challenges and communicating them to decision-makers so they can act," said Støre in his speech. 

Smol emphasised that science is a team effort, comparing himself to an ice hockey coach when receiving awards. "It’s the team that wins, but I get to lift the trophy," he said. 

"I have always had excellent teams of students and collaborators. Their contributions to our research have been remarkable," Smol added. 

Støre praised Smol for his ability to collaborate and nurture new talent: 

"By continuously highlighting and supporting everyone you work with, you demonstrate true leadership in research. For that, we all thank you," said Støre. 

Why Did Smol Receive the Prize?

The awarding of the Mohn Prize to Smol is more than an academic recognition—it is a tribute to a method that unlocks the past, enabling us to navigate the future. 

Smol is a scientific detective. His crime scene: Arctic lakes. His clues: microscopic remnants of life, preserved in sediment layers at the bottom of lakes. By reading these layers—some hundreds of thousands of years old—like the pages of a history book, he reveals how ecosystems have responded to changes over centuries. 

His work has provided methods to identify early warning signs of ecological disruptions. By studying diatoms and other microscopic organisms, he can precisely document when a lake became more acidic, when pollution first appeared, or how aquatic life changed as the climate warmed. 

This is not just academic curiosity—it is knowledge with immense practical value. Smol’s research has delivered concrete findings that have led to action against acid rain and pollution, with impacts far beyond local communities. He provides decision-makers with what they need most: a solid, scientific foundation for action. 

 

Smol has a unique ability to bridge the past and the present. He shows us that lakes have a memory. This memory is our best reference for assessing the changes we see today. Without a clear picture of what an ecosystem looked like before industrial impact, we are fumbling in the dark when setting goals for management, restoration, and conservation. 

 

When Prime Minister Jonas Gahr Støre presented the prize to Professor John P. Smol today at Arctic Frontiers, it was because Smol has shaped his field and inspired scientists worldwide. He has shown us that the small, often overlooked lakes of the Arctic are sensitive archives of the planet’s health. 

 

His work also carries a profound societal dimension. The knowledge he generates informs national and international negotiations. It is relevant to discussions on sustainable development, Indigenous rights, and the management of the fragile northern regions. 

About the Mohn Prize

• The international Mohn Prize for Outstanding Research Related to the Arctic was established in collaboration between Academia Borealis – The Academy of Sciences and Letters of Northern Norway, Tromsø Research Foundation, and UiT The Arctic University of Norway.
• The prize, worth 2 million NOK, is awarded every two years at Arctic Frontiers.
• John Smol is the fifth laureate, after Eddy Carmac (2018), Dorthe Dahl-Jensen (2020), John Walsh (2022) and Oran Young (2024).
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The laureate spoke to a packed room at Arctic Frontiers.

Credit

David Jensen / Arctic Frontiers

Prime Minister Støre emphasised Smol's contriburion to giving decicion makers a solid foundation.

Credit

Kjetil Rydland / UiT