City animals act in the same brazen ways around the world

Urban animals worldwide exhibit similar bold, opportunistic behaviours, such as food-stealing and reduced fear of humans, due to shared city environments and selective pressures favouring these traits. This behavioural homogenization is accompanied by a loss of behavioural and genetic diversity, reducing species' resilience to environmental change and complicating conservation efforts. The trend also increases potential for human-wildlife conflict and loss of unique, socially learned behaviours.

original article.

Loss of microbiota alters the profile of cells that protect the intestinal wall, experiments reveal

Research by scientists has made significant progress in understanding the relationship between gut microbiota and intestinal cells. The study, published in the journal Gut Microbes, showed how microbiota and the compounds it produces, such as butyrate, influence the functioning of cells that line the large intestine. This intestinal layer is in close contact with bacteria and produces mucus that contributes to its barrier function, helping to prevent bacteria from entering the body.
Loss of gut microbiota increases the abundance of a dual-function intestinal epithelial cell capable of both mucus secretion and nutrient absorption, a process regulated by microbiota-derived butyrate and its receptor GPR109A. This cell population expands in conditions of dysbiosis or aging, indicating adaptive epithelial plasticity and altered barrier function.
Among the findings is a description of the dual function of a cell that was previously thought to be exclusively mucus-secreting. The researchers discovered that the cell also absorbs nutrients and that its abundance in the epithelium is regulated by signals from the gut microbiota. The number of these cells increases when the gut microbiota is reduced.

The abundance of this cell is regulated by the production of butyrate—a compound resulting from the fermentation of dietary fiber—and its receptor, GPR109A. The more butyrate produced, the fewer of these cells there are.

This study paves the way for a better understanding of the role of microbiota and its metabolites in conditions such as inflammatory bowel disease and in developing treatments. Furthermore, the study demonstrates how the integrity of the intestinal wall can change, particularly in older individuals.
When the microbiota is reduced, the large intestine—which under normal conditions prioritizes mucus production—begins to express characteristics linked to nutrient absorption typically associated with the small intestine. We still don't know why this happens, but this change may be related to the expansion of dual-function cells and represent an adaptive response to the decrease in bacteria in this portion of the intestine, say the researchers.

Matheus de T. Moroti et al, Historical shifts, geographic biases, and biological constraints shape mammal species discovery, Journal of Systematics and Evolution (2026). DOI: 10.1111/jse.70040

Can drugs skip the blood-brain barrier?
Researchers have skipped the blood-brain barrier altogether by injecting drug-loaded nanoparticles into the space between skull bone layers. Immune cells then ferried these nanoparticles into the brain. In a randomized study of 20 stroke patients, clinical outcomes were better in the group where treatment was also injected through the skull, compared to the standard of care. The ability to skip the blood-brain barrier in its entirety could be massively useful for treating many brain-based disorders, but there’s a lot more work in store, writes medicinal chemist Derek Lowe.

https://www.sciencedirect.com/science/article/pii/S0092867425014217...