It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
Thursday, March 26, 2026
Well-fed penguins live longer but age faster — much like modern humans
In public discourse, the increasing lifespan in Western countries is often linked to longer life in good health. However, studying human aging in modern societies is complex because outcomes are shaped by numerous social, behavioral, and environmental factors, including medical advances, food security, poverty, alcohol use, and civil violence.
Penguins: A Clearer View of Physiological Aging
Penguins serve as an excellent model for understanding aging: they live 20–40 years, providing a reasonable timescale for research relevant to humans. Moreover, penguins have not undergone the same complex socio-economic changes as humans in Western countries over the past centuries.
"We wanted to investigate whether turning these penguins into nonchalant, well-fed, and well-cared-for individuals would alter their aging trajectory. Since this lifestyle already occurs in zoos, the setup was ideal," says Robin Cristofari from the University of Helsinki, first author of the new research paper published in Nature Communications.
The well-fed and sheltered environments for king penguin groups at Zoo Zurich (Switzerland) and Loro Parque (Tenerife/Spain) model conditions that closely resemble the modern human lifestyle. The results are unambiguous: living in a zoo accelerates the aging process in penguins.
"A 15-year-old penguin in the zoo has the body of a 20-year-old penguin in the wild. However, the interesting part is that zoo penguins also live longer, overall. They may be less physically fit, but with no natural predators or Antarctic storms to contend—with and with access to veterinary care—they can survive long past the age at which they would typically die in the Southern Ocean", explains a co-researcher Céline Le Bohec, from the French CNRS, who has studied King penguins in the wild for over two decades.
Researchers linked their findings to mechanisms involved in metabolism, as well as cellular growth, and maintenance. The key finding was that zoo conditions – including free access to food on a regular basis, limited physical activity, and the disruption of life rhythms – ultimately lead to accelerated aging.
How to Live Long and Stay Healthy?
Both penguins and humans live longer in modern environments with advanced health care, but this does not necessarily translate into improved health at older ages. Cristofari and his co‑researchers aim to understand what kind of lifestyle supports not only longer, but also healthier lives for penguins.
“We are currently conducting a study in which we induce penguins to eat less and exercise more. It is important to find a moderate lifestyle in a world of abundance - for us humans as well,” concludes research curator Leyla Davis from Zoo Zurich.
The article titled “Lifestyle Change Accelerates Epigenetic Aging in King Penguins” was published in Nature Communications as a result of collaboration among the University of Helsinki, CNRS, the University of Hamburg, and Zoo Zurich.
The arrow indicates a chloroplast stolen from algal prey (a kleptoplast) inside an R. viridis cell. The study shows that proteins made by the host are transported into this kleptoplast, where they help keep key chloroplast machinery working.
Every plant cell is the product of a biological merger billions of years ago. Chloroplasts are key structures in plants and algae that capture sunlight, but originally they were free-living bacteria that took up residence inside another cell. Over time, these partners became more closely integrated by sharing genes, proteins, and roles.
To understand how this process happened, scientists look for organisms that display similar processes. A tiny predator named Rapaza viridis may offer a glimpse of some of the early steps involved in that ancient transformation.
R. viridis is a single-celled organism that performs photosynthesis using chloroplasts stolen from the green alga it consumes. This process is called kleptoplasty—from the Greek word for thief.
Even after the algal nucleus and much of the cytoplasm are lost, the prey-derived chloroplasts remain inside R. viridis. Temporarily, structures from two different organisms coexist within a single cell, which can be described as structural-level chimerism.
Using genetic engineering and biochemical approaches, research led by Masami Nakazawa, a lecturer at the Graduate School of Agriculture, Osaka Metropolitan University, and Professor Yuichiro Kashiyama at the Faculty of Environmental Studies, Fukui University of Technology, has found that the kleptoplasts in R. viridis also exhibit chimerism at the molecular level. This suggests a more advanced form of kleptoplasty than structural-level chimerism alone.
The group identified host-made proteins that are transported into the stolen chloroplast, where they help keep key chloroplast machinery working. When the researchers disrupted the genes encoding these proteins, the stolen chloroplasts functioned less effectively.
Their findings suggest that by producing proteins that function within the stolen chloroplast, R. viridis goes beyond simple prey retention and offers a valuable model for studying how deeper host–organelle integration can arise.
“This makes R. viridis the first organism in which proteins encoded in the host’snucleus have been biochemically shown to function inside a stolen organelle from another species,” Professor Kashiyama said. “These findings show that even temporary chloroplast retention can involve a deeper level of host–organelle integration than previously recognized.”
Dr. Nakazawa believes that experiments like these can help researchers understand what happened when the first plant cells emerged. “By revealing mechanisms at work when eukaryotic cells use foreign organelles, going beyond what we typically see in model organisms, this study provides clues to the evolutionary processes that gave rise to plant cells,” she said.
The study was published in Nature Communications.
A protein made byR. viridiscarries a targeting signal that directs it into a chloroplast stolen from a green alga, where it functions as part of a protein complex.
Credit
Osaka Metropolitan University
Competing Interests Statement:
The authors declare that they have no competing interests.
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Scanning electron microscope image showing syntrophic acetate-oxidizing (SAO) bacteria (blue rods) and methanogenic archaea (red cocci) interacting on conductive particles. The bacteria oxidize acetate to CO₂, releasing electrons (e⁻) that travel via the particles to the archaea, which reduce CO₂ to methane (CH₄). Image collected by D. Jovicic and J. Fiutowski; schematic created in BioRender (Rotaru, A., 2026). https://BioRender.com/1z598ch
Deep below the sediment surface in coastal environments, microbes are using tiny conductive particles—like natural “electric wires” – to team up and produce methane, a potent greenhouse gas. A new study published in Nature Communications and led by researchers at the University of Southern Denmark, in collaboration with researchers at Aarhus University, uncovers novel lineages of microorganisms that rely on conductive particles to convert organic carbon to methane, a process that could influence global carbon cycling.
Conductive particles occur naturally in sediments, for example iron oxides such as magnetite, and can enter sediments through human activities, such as chars from forest fires, or soot from industrial pyrolysis. These particles, or their analogues, have been shown to promote methane production in both laboratory partnerships and natural communities. However, it remained unclear which microorganisms are responsible in natural environments and how they interact via conductive particles.
The authors had previously shown that a bacterial-archaeal partnership from coastal sediments was not just promoted by conductive particles, but required conductive particles to convert a simple organic compound, acetate, to methane. A decade ago, they collected sediment samples from the coastal zone of the northern Baltic. They then found that in the laboratory, these methane-producing communities could be propagated only in the presence of conductive particles. However, without genome sequences for the key players, the identity of the partners, and the mechanism by which they collaborate on conductive particles, remained a mystery.
Now, by reconstructing genomes from these consortia bound to conductive particles, the team discovered that the key bacterium belonged to a new genus of bacteria, which they named Candidatus Geosyntrophus acetoxidans because it is a syntrophic bacterium that oxidizes acetate. The partner methanogen was a new species of Methanosarcina that relies on electrons from its partner (received via the conductive particles) to reduce carbon dioxide to methane. This process is known as conductive particle-obligate syntrophic acetate oxidation, and this environmental consortium is the only described example of this type.
A microbial power grid
Unlike traditional microbial partnerships, where cells exchange small molecules or must touch to exchange electrons directly, this partnership uses the conductive particles as a “shared electrical grid”, allowing them to collaborate even when physically separate.
“This is like finding a hidden network of partners wired by the conductive grains in the seafloor”, said Amelia-Elena Rotaru, senior author of the study and group leader at the University of Southern Denmark. ”It shows that we have been missing an important group of climate-relevant microorganisms and a mechanism by which they can drive methane production in sediments”.
The two cell types do not need to be near one another, and high-resolution imaging showed that they both “plug” into the conductive particle to exchange electrons. “In this community, electrons don’t have to move from cell to cell by direct contact—the particles in the environment serve as the electron transfer conduit”, said Amelia-Elena Rotaru.
New microorganisms—found by sequencing genomes of coastal environmental consortia
In this new study, the team reconstructed genomes from this conductive-particle-dependent consortium, which was propagated in the laboratory for many generations over the course of 10 years.
They discovered that the key player was a previously uncharacterized bacterium, Ca. Geosyntrophus acetoxidans. This bacterium is the first cultured relative of a previously undescribed genus.
Genomic analysis showed that it contains a complete pathway for the uptake and oxidation of acetate, as well as a suite of genes associated with extracellular electron transfer, including multiheme cytochromes and conductive pili. The genes for this electron transfer machinery showed very little similarity to those of other bacterial lineages capable of extracellular electron transfer. This bacterium releases electrons onto the conductive particle on which it resides. The partner methanogen then receives electrons from the conductive particles on which it also resides. The methanogen was a new species of Methanosarcina, a globally widespread group of methanogens. It had its own multiheme cytochrome on the cell surface, which is known to facilitate electron uptake from insoluble sources outside the cell, and a full CO2-reduction methanogenesis pathway.
“The exciting part is that this wasn’t just ‘we detected a new group of organisms from the environment’,” said Danijel Jovicic, co-lead author. “We can now link a specific, previously uncharacterized bacterium and methanogen to an electron-transfer partnership that ends in methane production—and we can see the molecular machinery for acetate-oxidation, methane-formation and interspecies electron-transport in the genomes.”
“Our results show a mechanism that could lead to greenhouse gas emissions in environments where conductive particles accumulate, and that is something climate and environmental research should also account for.” Rotaru said.
This work was supported by a Danish Research Council grant awarded to Amelia-Elena Rotaru (PI, SDU) and Bo Barker Jørgensen (Co-PI, AU), and by a European Research Council Consolidator Grant awarded to Amelia-Elena Rotaru at the University of Southern Denmark.
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Candidatus Geosyntrophus acetoxidans. The name reflects both where this microbe lives and how it survives. ‘Candidatus’ means it has not been grown alone in the lab. ‘Geosyntrophus’ comes from the Greek words for earth or ground (Gē), and for living together or feeding together (syntrophos), reflecting that this Earth microbe lives in metabolic partnership with others. The species name ‘acetoxidans’ refers to its ability to oxidize acetate.
Extracellular electron transfer is a way some microorganisms ‘respire’ without oxygen. In microorganisms that ‘respire’ oxygen, electrons taken from food are passed through a chain of membrane proteins inside the cell to oxygen. This ultimately gives the cell a form of energy it can use for work inside the cell. A similar process also happens in our own cells, in the mitochondria. Some microbes, that live without oxygen do something different. Instead of passing electrons to oxygen inside the cell, they move them out of the cell through specialized proteins on their cell surface and transfer them to minerals, conductive particles or even partner cells nearby. This process is called extracellular electron transfer.
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Paper details:
Title: Genome-centric metagenomics reveals novel electroactive syntrophs in a conductive particle-dependent consortium from coastal sediments. Authors: Danijel Jovicic, Konstantinos Anestis, Jacek Fiutowski, Bo Barker Jørgensen, Kasper Urup Kjeldsen, Amelia‑Elena Rotaru. Affiliations: University of Southern Denmark; Aarhus University; SDU NanoSYD (Mads Clausen Institute). Corresponding author: Amelia‑Elena Rotaru (arotaru@biology.sdu.dk).
Journal
Nature Communications
Method of Research
Experimental study
Subject of Research
Cells
Article Title
Genome-centric metagenomics reveals electroactive syntrophs in a conductive particle-dependent consortium from coastal sediments
