In this newsletter we discuss how Mycobacterium tuberculosis – the bacterium that causes tuberculosis – can hide in the liver. Tuberculosis has long been associated with the lungs, but it can also spread to other parts of the body, including the brain. Now, researchers have found that M. tuberculosis can infect liver cells called hepatocytes. These cells contains reserves of fat that the bacteria rely on to survive inside the liver. However, it might be possible to target the bacteria by blocking the cellular pathways that produce this fat. Plus, keeping track of neurons in the growing brain, and the evolution of teeth in sharks.
This is the last eLife Magazine Highlights of 2025 – the next edition will be January 13, 2026.
– Peter Rodgers, Chief Magazine Editor, eLife
Microscopy image of the cerebellum of an aged mouse: the bright green stripes are composed of surviving Purkinje cells, and the dark stripes indicate neurodegeneration.
During healthy aging, a region of the brain called the cerebellum becomes smaller. This shrinkage is partly caused by the loss of neurons, particularly Purkinje cells, and is often accompanied by behavioural deficits. Age-related neurodegenerative diseases also involve neurodegeneration and impaired behavioural capacity. Now, as reported in eLife, researchers have found that the Purkinje cells that survive the aging process in mice form a pattern of long, narrow stripes that run front-to-back through the cerebellum. A better understanding of mechanisms underlying neurodegeneration should help researchers trying to develop treatments for age-related neurological disorders.
Tuberculosis (TB) is spread by people inhaling tiny airborne droplets that carry pathogenic bacteria called M. tuberculosis, and once inside the lungs, these bacteria settle into macrophages and other immune cells, where they can remain dormant for years – surviving inside the very cells that are meant to kill them. However, M. tuberculosis can also take up residence in other parts of the body, such as the lymph nodes. Now, as explained in this Insight article, M. tuberculosis can also hide in the liver by infecting cells called hepatocytes. This came as a surprise because the liver is responsible for detoxing the body, but hepatocytes make attractive hiding places because they are numerous – they account for about 80% of the mass of the liver – and they contain stores of fat that the bacteria can use to survive inside the liver. This finding suggests that cutting off the pathogen’s food supply in the liver (by blocking the cellular pathways involved in the storage of fat) may weaken it and make existing drugs against TB more effective.
The brain changes rapidly in the days after birth. In particular, circuits reorganize, patterns of neuronal activity change, and neurons grow and change both their appearance and their position relative to each other. This means that the methods used to track dense population of neurons in adult animals often fail when applied to young pups. Now, as highlighted in this Insight article, researchers have developed an elegant solution to this problem that enables daily tracking of the same set of neurons in young mice during a period of rapid brain growth. The researchers used an established technique to image the neurons every day between eight and fourteen days after birth, and then used a new computational method called Track2p to align these images in a way that compensates for natural growth. Instead of forcing the images to fit a fixed template, Track2p adjusts each day’s image relative to the previous one to smooth out the changes caused by tissue expansion. The new approach also revealed a surprisingly abrupt shift in brain activity – from neurons being active together in large, highly synchronized bursts, to their activity being more diverse and less synchronized – around eleven days after birth.
Teeth have evolved over millions of years to accommodate a wide range of diets and habitats, so studying and comparing the teeth of different species has the potential to reveal details about past ecosystems and animal behaviours. Now, in a recent paper in eLife, researchers have done this for all extant species of a creature notorious for its teeth – the shark. The researchers developed a new methodology for comparing both individual teeth and dentition (the number, kind and arrangement of teeth), and combined this with genomic data. They found that some features were mostly influenced by genetics, while others were mostly influenced by environment (for example, did the species live in the deep sea or the open ocean?). The findings provide new insights into adaptation and evolution in integrated biological systems, and may also offer new avenues for studying long-term changes in marine ecosystems.
The cerebellum (which is Latin for ‘little brain’) is the area of the brain in charge of fine motor coordination and balance, and it also has a crucial role in cognition and language processing. Understanding how the cerebellum – which contains a staggering 80% of the brain’s neurons – works with the rest of the brain is a central challenge in neuroscience. Neurons called climbing fibers help shape the output that is sent from the cerebellum to many areas of the brain and body. Now, as highlighted in this Insight article, researchers have revealed details of how climbing fibers influence neurons in the somatosensory cortex, which is part of the the cerebral cortex (the outer layer of the brain). In particular, they show that climbing fibers can influence the plasticity – that is, the ability to change in response to experience – of the somatosensory cortex.
A “digital twin” is a digital copy of an object in the real world that can be used to predict how the object will respond to various interventions. To date digital twins have mostly been used in the physical sciences and engineering to study objects such as power plants, vehicles and spacecraft. Now, as David Adam reports in PNAS, researchers in the life sciences are starting to use digital twins. In particular, researchers can use scanning technologies to build a digital twin of the heart of a patient with a certain heart condition, and then use the digital twin to predict the impact of various medical procedures.
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