Bacteria evolved to help neighboring cells after death, new research reveals

Durham University

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Darwin’s theory of natural selection provides an explanation for why organisms develop traits that help them survive and reproduce.   

Because of this, death is often seen as a failure rather than a process shaped by evolution.   

When organisms die, their molecules need to be broken down for reuse by other living things.   

Such recycling of nutrients is necessary for new life to grow.   

Now a study led by Professor Martin Cann of Durham University’s Department of Biosciences has shown that a type of E-coli bacteria produces an enzyme which breaks the contents of their cells down into nutrients after death.   

The dead bacteria are therefore offering a banquet of nutrients to the cells that were their neighbours when they were living.  

Professor Cann said: “We typically think of death being the end, that after something dies it just falls apart, rots and becomes a passive target as it is scavenged for nutrients.   

“But what this paper has demonstrated is that death is not the end of the programmed biological processes that occur in an organism.   

“Those processes continue after death, and they have evolved to do so.   

“That is a fundamental rethink about how we view the death of an organism.”   

The study has been published in the journal Nature Communications.  

Co-author Professor Wilson Poon, from the School of Physics and Astronomy of the University of Edinburgh, inspired the research after posing what he believed were some unanswered questions about why organisms die the way they do.  

The researchers assembled and realised they had stumbled across a potentially new area of biology; processes that have evolved to function after death.   

Professor Cann said: “One problem remained; we couldn’t work out how an enzyme that functions after death could have evolved.   

“Typically, we think of evolution acting on living organisms not dead ones.  

“The solution is that neighbouring cells which gain nutrients from the dead cells are likely to be clonally related to the dead cell.   

“Consequently, the dead cell is giving nutrients to its relatives, analogous to how animals will often help feed younger members of their family group.”   

Co-author Professor Stuart West of the University of Oxford added: “This is like nothing we have observed before – it is equivalent to a dead meerkat suddenly turning into a pile of boiled eggs that the other members of its group could eat.”  

The finding demonstrates that processes after death, like processes during life, can be biologically programmed and subject to evolution.   

Biomolecules that regulate processes after death might be exploited in the future as novel targets to bacterial disease or as candidates to enhance bacterial growth in biotechnology.  

Professor Poon suggests that modelling such processes using the tools of statistical physics may also provide design principles for humans as we move towards a more circular economy in which recycling needs to be built in from the beginning.  

ENDS  

Media Information   

Interviews   

Professor Martin Cann of Durham University’s Department of Biosciences is available for interview and can be contacted at m.j.cann@durham.ac.uk  

Alternatively, please contact Durham University Marketing and Communications Office on communications.team@durham.ac.uk or +44(0)191 334 8623.  

Source Information  

‘Bacteria encode post-mortem protein catabolism that enables altruistic nutrient recycling’, Martin J. Cann et al., is published in the journal Nature Communications.  

DOI: 10.1038/s41467-025-56761-6  

The full study will be available via the following link once the embargo has lifted: https://www.nature.com/articles/s41467-025-56761-6 

About Durham University

Durham University is a globally outstanding centre of teaching and research based in historic Durham City in the UK.

We are a collegiate university committed to inspiring our people to do outstanding things at Durham and in the world.

We conduct research that improves lives globally and we are ranked as a world top 100 university with an international reputation in research and education (QS World University Rankings 2025).

We are a member of the Russell Group of leading research-intensive UK universities and we are consistently ranked as a top 10 university in national league tables (Times and Sunday Times Good University Guide, Guardian University Guide and The Complete University Guide).

For more information about Durham University visit: www.durham.ac.uk/about/

​END OF MEDIA RELEASE – issued by Durham University Communications Office.

 

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Journal

Nature Communications

DOI

10.1038/s41467-025-56761-6 

Method of Research

Observational study

Subject of Research

Cells

Article Title

Bacteria encode post-mortem protein catabolism that enables altruistic nutrient recycling

Article Publication Date

13-Feb-2025

 

Lack of discussion drives traditional gender roles in parenthood

University College London

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Conversations about parental duties continue to be led by mothers, even if both parents earn the same amount of money, finds a new study by a UCL researcher.

A new study by Dr Clare Stovell (IOE, UCL’s Faculty of Education & Society), published in the Journal of Family Studies, highlights how a lack of discussion between parents about important choices such as parental leave, work and childcare is perpetuating traditional gender roles.

The study found that women usually lead the conversations and there is little discussion about the man’s work schedule, even in cases where the woman earns as much or more than her partner.

Dr Stovell said: “These interviews indicate there are engrained and unquestioned expectations for fathers to work full-time, while mothers take on the primary carer role through long maternity leaves, followed by a reduction in working hours, even where women are equal or higher earners.”

Dr Stovell interviewed 25 professional couples in the UK in 2017-2018 and found that they rarely discussed or negotiated important decisions about work and family after becoming parents.

Instead, women usually led the conversations, focusing on non-parental childcare options and how they may be able to adapt their own work patterns.

The research found that there were four key reasons for this:

• Traditional ideas about gender roles (i.e. the expectation that the mother does the bulk of the childcare provided a default for parents to follow.)
• Not realising the risk of falling into traditional gender roles (i.e. not being aware of the need for active discussions to achieve equitable outcomes when becoming parents. Couples regretted not having discussed more, only realising later that it was necessary.)
• No strong reason to discuss the man’s work schedule (i.e. decisions tended to be initiated by external factors, like nursery waiting lists and employer deadlines, which were not focused on fathers.)
• Men being unsure of how to start the conversation (i.e. fathers having a fear of creating tension or encroaching on the mother’s right to maternity leave. The current shared leave policy, which is based on women transferring their leave, does not offer men the opportunity to make genuine decisions about sharing leave and puts all the decision-making efforts onto women.)

For example, one father who was interviewed said: “So having that conversation with a mother-to-be who’s pregnant as well, it’s kind of like, I wouldn’t want to go there! I think if you’re just going to your wife or girlfriend ‘do you want to share your maternity’, I don’t know. You’re saying it there, ‘your maternity’, it is theirs. You might get the wrong reaction.”

Another father who took shared leave added: “I think to be honest she was much more proactive than me, thinking ahead to how things might work out. […] I definitely remember her coming home and saying ‘oh, you know, we could do it this way or that way’. So, she definitely drove that decision.”

The study also found that couples tended not to calculate costs of various different options, but instead calculated whether their preferred option was affordable. Decisions were therefore often based only on assumptions about what was financially viable – and weren’t necessarily accurate.

As a result of the findings, Dr Stovell is calling on families, organisations, schools and policymakers to support active decision-making to help couples share work and family duties more equally.

Dr Stovell said: “Despite the expectation that couples would discuss and negotiate work-family decisions before becoming parents, these findings suggest that manyare make these decisions individually, especially women, and often without explicit discussions.

“This highlights the need for better support and awareness to achieve a more equal sharing of responsibilities. For example, women and men at the beginning of their career trajectories should be actively encouraged and supported to proactively plan for changes in their working arrangements in the event of having children.

“Equally, organisations and policy makers also have an important role to play in providing catalysts for couples to discuss the work-family balance for fathers, including more generous non-transferable leave provision to fathers – i.e. an individual entitlement to more than two week’s leave - and active support for flexible working.”

The research was funded by the Economic and Social Research Council (ESRC).

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Journal

Journal of Family Studies

DOI

10.1080/13229400.2025.2462929 

Method of Research

Survey

Subject of Research

People

Article Title

“Work-family decision-making processes at the transition to parenthood: why aren’t heterosexual couples discussing some of the most important decisions of their lives?”

Article Publication Date

13-Feb-2025

 

Chinese scientists find key genes to fight against crop parasites

Chinese Academy of Sciences Headquarters

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image: 

Knocking out SbSLT1/2 reduces the amount of SL in root exudates, decreases Striga germination, and potentially mitigates yield loss in infested regions. In this illustration, on the left is shown the wild-type (WT) sorghum releasing SLs, which trigger Striga germination and infection, resulting in yield loss. "Striga" means "witch" in Latin, and the ghost depicted represents its harm to crops. On the right, the SbSLT1/2-knockout sorghum demonstrates a strong ability to resist Striga.

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Credit: XIE Qi

Chinese scientists have identified two key genes responsible for sorghum's resistance to Striga, a parasitic plant that causes significant crop losses. The breakthrough, which also highlights the potential of AI to predict key amino acid sites in strigolactone (SL) transporters, could have wide-ranging applications in enhancing parasitic plant resistance across various crops.

This study, published in Cell, was conducted by Prof. XIE Qi's team at the Institute of Genetics and Developmental Biology of the Chinese Academy of Sciences, in collaboration with five other institutions.

Striga, also known as "witchweed," along with other parasitic plants like Orobanche, relies on host plants for nutrients and water, severely affecting crop yields and agricultural ecosystems. Striga alone infests over 50 million hectares of farmland in Africa, causing annual economic losses of $1.5 billion and affecting over 300 million people. In China, Striga is found in regions such as Guangdong and Yunnan, while Orobanche poses a threat to crops like sunflowers and tomatoes in Inner Mongolia and Xinjiang.

Sorghum is one of the plants susceptible to Striga infestation. Sorghum roots release SLs, a class of plant hormones that help recruit mycorrhizal fungi for nutrient uptake. Unfortunately, Striga seeds dormant in the soil detect these SL signals, which trigger Striga germination and subsequent infestation of the host plant.

In this study, the researchers analyzed transcriptome data from sorghum roots under phosphorus-deficient conditions and strigolactone (SL) treatmen separately. The scientists identified two ABCG family SL transporter genes: Sorghum bicolor SL transporter 1 (SbSLT1) and Sorghum bicolor SL transporter 2 (SbSLT2). They determined that the SbSLT1 and SbSLT2 proteins control the efflux of SLs and knocking out the associated genes inhibits SL secretion. Under these conditions, Striga is unable to germinate and infect the host.

AI-based predictions further identified a conserved phenylalanine residue critical for SL transport. This residue is found not only in sorghum, but also in SL transporters across other monocot crops like maize, rice, and millet, as well as dicotyl crops such as sunflowers and tomatoes, suggesting a conserved mechanism across species. Molecular biology and cellular biology experiments demonstrate the key function of this residue.

Field trials conducted in Striga-prone areas showed that sorghum with knocked-out SbSLT1 and SbSLT2 genes exhibited 67–94% lower infestation rates and 49–52% less yield loss. These findings offer valuable genetic resources and technical support for breeding Striga-resistant sorghum varieties.

The researchers emphasized that the discovery of SbSLT1 and SbSLT2 could provide crucial tools for combating parasitic plants, potentially addressing food security challenges in countries severely affected by parasitic plants, especially African and Asian countries, thereby contributing to regional peace and stability. Future research will focus on validating these genes in crops such as maize, tomato, and millet, with the goal of advancing the commercialization of Striga-resistant crops.

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Journal

Cell

DOI

10.1016/j.cell.2025.01.022 

Method of Research

Meta-analysis

Subject of Research

Cells

Article Title

Resistance to Striga Parasitism through Reduction of Strigolactone Exudation

Article Publication Date

12-Feb-2025

 

New study identifies brain region that can prevent aggressive social behavior and induce pro social behavior

The Mount Sinai Hospital / Mount Sinai School of Medicine

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image: 

Graphic representation of study findings. 

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Credit: Mount Sinai Health System

 

 

Nature article entitled:
A critical role for the cortical amygdala in shaping social encounters
[https://doi.org/10.1038/s41586-024-08540-4]

Bottom Line: Neural activity in the cortical amygdala determines whether mice engage in aggressive or pro-social behavior 

Results: By performing a network analysis on whole-brain activity of male mice, we identified the cortical amygdala – an olfactory cortical structure – as a key brain region in promoting aggression. This brain region is activated by olfactory cues from male mice and by aggressive behavior. Inhibiting the cortical amygdala reduces aggressive behavior and induces pro-social behavior.

Why the Research Is Interesting:  This is the first study that identified a brain region that can prevent aggressive social behavior and induce pro social behavior.

Study Conclusions: Cells in the cortical amygdala respond specifically to male social stimuli thereby enhancing their salience and promoting attack behaviour.

First Author: Antonio Aubry, PhD
Senior Author: Scott Russo, PhD

Said Mount Sinai's Dr. Aubry of the research: “Aggression is an evolutionarily conserved behavior that controls social hierarchies and protects valuable resources. However, aggression can become maladaptive and pose threats to patients and caregivers. Modeling and understanding the behavioral etiology of aggressive behavior is therefore a health priority. In order to discover novel brain regions which are involved in aggression behavior, we performed a network analysis on brain wide activity at the single cell level.  This analysis identified the cortical amygdala, an olfactory cortical structure, as a key brain region in promoting aggression. This brain region is activated by olfactory cues from male mice and by aggressive behavior. Importantly, we found that inhibiting the cortical amygdala and it’s downstream circuits reduces aggressive behavior and induces pro-social behavior."

Keywords: Social behavior, aggression, cortical amygdala

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Journal

Nature

DOI

10.1038/s41586-024-08540- 

Method of Research

Experimental study

Subject of Research

Animals

Article Title

A crucial role for the cortical amygdala in shaping social encounters

Article Publication Date

12-Feb-2025

 

Symbiotic bacteria ride along with marine cells in ocean’s upper layer

Marine Biological Laboratory

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By Wynne Parry

Just as the human body serves as a habitat for bacteria and other microbes, diverse, tiny organisms known as protists host their own microbiomes.

In new research published this week, a team led by Marine Biological Laboratory (MBL) scientists reveals that symbiotic bacteria often accompany single-celled protists in the ocean’s upper layer. Some of these symbionts, they discovered, are close relatives of bacteria pathogenic to animals, including humans.

“We know there are many symbionts in the world, but it was surprising to find that smallest, and most common predatory protists in the ocean have symbionts living with them,” says senior author Alexandra Worden, a senior scientist at MBL.

The protists her team studied are among the smallest in the ocean, measuring two to five microns, roughly the size of a dust particle or small mold spore.

The discovery of these symbiont lineages sheds light on the evolution of their bacterial relatives – whether symbionts or pathogens – insight that could help researchers understand disease vectors and the infections they cause in people.

Marine Protists are Elusive – and Essential

Protists are a diverse, catchall group. Most are unicellular, but with features that disqualify them from grouping with other types of life like animals, plants, fungi, bacteria, and archaea.

In the ocean, some protists function like plants, using light to manufacture their own food. Others, such as choanoflagellates, which are animals’ closest living unicellular relatives, envelop and digest still smaller cells. Ocean ecosystems depend on these predators and browsers to consume plant-like phytoplankton and other bacteria, and, in turn, become food for the tiny marine animals that fish eat. 

Scientists have had difficulty studying their contribution to marine food webs, in part because they can’t coax these organisms to grow in the lab. To get around this problem, Worden developed a method for examining individual protist cells fresh out of the ocean using equipment brought onto research vessels – rather than in stable, climate-controlled rooms in hospitals and research centers, as usual.

“It has been an incredible team effort by students, technicians, and postdocs in the lab over the years to make these discoveries. A lot of perseverance and work within the constraints of the expeditions and weather!” she says.

After retrieving water samples from the North Pacific and other locations, researchers in her group stain the protists’ food vacuole — equivalent to their stomachs. This stain makes it possible to select the protists that interest the researchers: those eating other things. After separating out the individual protists, the researchers then identify the bacteria within or attached to them using genetic sequencing. (Their analysis looked only at whole bacteria, not the ones the protists had recently eaten.)

Then they worked with collaborators in the BIOS-SCOPE project, taking what they had learned to analyze data collected on a monthly basis over multiple years in the North Atlantic, in order to understand seasonal dynamics.

Studying these symbionts is essential to fully understanding the protists’ biology, similar to how the human microbiome is crucial to our health, according to Worden. “They could be fundamental to how the protists live and grow in the ocean,” she says.

Harmful or Helpful? Symbiosis in Protists and in Humans

Unlike the human microbiome, which hosts trillions of symbiont cells, the much smaller protists can likely carry a small handful.

In research published in Nature Microbiology in 2022, Worden’s team used on-board cell sorting to identify one type of bacterial symbiont, dubbed Comchoano, within a species of choanoflagellate. It and four other groups of bacteria showed up within the many protist cells analyzed for the present study. Of the four new symbiont lineages, three have close evolutionary links to human pathogens that live as symbionts in insects, such as ticks.

One of these lineages is closely related to Coxiella, a group that contains the germs responsible for the flu-like Q fever. Meanwhile, the others belong within a group that includes Rickettsia, members of which can cause Rocky Mountain spotted fever, typhus, and other infections.

In spite of their links to disease in mammals, it's not clear if these microbes help or harm their protist hosts. Context makes all the difference in these relationships, says Worden, noting that bacteria such as Rickettsia aid their insect hosts, only causing disease once they arrive within humans or other mammals.

“There’s an arc from our symbionts, all the way to disease in humans,” says first author Fabian Wittmers, who conducted the research while a BIOS-SCOPE graduate student in Worden’s Lab. 

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The Marine Biological Laboratory (MBL) is dedicated to scientific discovery – exploring fundamental biology, understanding marine biodiversity and the environment, and informing the human condition through research and education. Founded in Woods Hole, Massachusetts in 1888, the MBL is a private, nonprofit institution and an affiliate of the University of Chicago.

 

  

Strategy for discovering protist – bacterial interactions in the ocean. The strategy relied on working at-sea where uncultivated cells could be interrogated without any form of fixation. The cartoon shows the approach, moving from the upper left corner clockwise. The active phagocytic vacuoles of uncultivated predatory protists were illuminated with fluorescent dye(s) and the unique emission from these stains was used to discriminate the predatory protists from other microbes and photosynthetic protists (phytoplankton). This involved use of light scatter signatures and autofluorescence optimized to select and exclude photosynthetic protists and other microbes. After sorting into individual wells with a variety of controls (see Method Details) plates were frozen until subsequent steps depicted in the cartoon. From Wittmers et al., Cell Host & Microbe, 2025.

Credit

From Wittmers et al., Cell Host & Microbe, 2025 (Alex Worden Lab, MBL).

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Journal

Cell Host & Microbe

DOI

10.1016/j.chom.2025.01.009 

Method of Research

Experimental study

Subject of Research

Cells

Article Title

Symbionts of Predatory Protists are Widespread in the Oceans and Related to Animal Pathogens

Article Publication Date

12-Feb-2025