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Good news around the world
A simple touch brings bleached coral back to life
A discovery made almost by accident in an aquarium at Stanford University in the United States could help save coral reefs, one of the ecosystems most threatened by ocean warming.
When water temperatures rise too high, corals expel the microalgae living in their tissues that provide them with food and color. They turn white and, without help, eventually die. In 2025, biologist Stephen Palumbi noticed that a fragment of bleached coral began to regain its color after touching a healthy fragment from the same colony.
The team decided to test the hypothesis. They paired five sets of fragments—one healthy and one bleached and kept another five pairs separated by just a few millimeters. The results, published this month in the journal Science Advances, are striking: all the corals that were in direct contact fully recovered within seven weeks, while all those kept apart died.
Under the microscope, scientists observed small channels forming between the tissues, through which algae passed from the healthy coral to the sick one in just three days. Between five and seven days of contact were enough to ensure recovery.
Researchers admit that the method cannot yet be applied on a large scale, as each sick coral would require a healthy “twin.” They are now studying ways to collect and transfer beneficial algae before marine heatwaves strike. For the reefs, it is a rare beacon of hope.
Walking half an hour a day can slow Alzheimer’s
You don’t need the famous 10,000 daily steps to protect your brain. Science increasingly shows that around 3,000 steps, the equivalent of a moderate half-hour walk, are enough to delay signs of Alzheimer’s disease.
The conclusion comes from an American study that followed nearly 300 older adults showing early signs of the disease in their brains over nine to eleven years. Participants used pedometers to track physical activity. Among the most active, signs of cognitive decline were reduced by almost half.
Walking did not eliminate amyloid protein plaques, which are the target of most current medications. However, it was associated with a lower accumulation of another protein, tau, which is more directly linked to memory loss and reduced independence. The strongest effect appeared between 5,000 and 7,500 daily steps, stabilizing after that point.
These findings build on other research. A large British study involving more than 78,000 people had previously found a 25% lower risk of dementia in those who took around 3,800 steps per day.
Scientists urge caution, noting that the sample size was small and active individuals tend to have other healthy habits. Even so, the message is encouraging: a simple, free gesture accessible to almost everyone can make a real difference in brain health.
Tigers, turtles, and tuna: nature can recover
The latest Living Planet Report, published this month by the WWF, presents worrying figures on the decline of wildlife. However, it also demonstrates that conservation works when there is will and investment.
The most striking example is the tiger. In 2010, fewer than 3,200 tigers remained in the wild, and the species seemed doomed. That year, the 13 countries where the animal lives committed to doubling the population. Today, there are approximately 5,700 tigers, a 70% increase, thanks to anti-poaching efforts and habitat protection.
There is also good news in the oceans. In 2025, the green sea turtle became the first sea turtle to move from “endangered” to “least concern” on the IUCN Red List. Decades of protecting nesting beaches and reducing accidental bycatch contributed to this success.
The Atlantic bluefin tuna, which was on the brink of collapse due to overfishing, has recovered sufficiently to no longer be considered threatened. This was the result of strict fishing quotas and tight enforcement. In South Africa, elephant populations are also stable or growing in areas managed directly by local communities.
Experts emphasize that these successes are fragile and depend on long-term commitments. However, they prove that biodiversity loss is not inevitable.
Nobel Prize honors technique that switches neurons on and off with light
The 2026 Nobel Prize in Physiology or Medicine recognized a discovery born from a deceptively simple question: how does a microscopic alga “see” light?
Germans Peter Hegemann of Humboldt University in Berlin and Georg Nagel of the University of Würzburg discovered that the Chlamydomonas alga possesses a protein, channelrhodopsin, that opens a passage in the cell membrane when struck by light. American Karl Deisseroth of Stanford University recognized the potential of this discovery and developed optogenetics.
The technique involves introducing the gene for this protein into specific neurons, causing them to respond to light. Using a fine beam of light delivered via an ultra-thin optical fiber, scientists can activate or deactivate groups of cells with extreme precision, without affecting neighboring ones.
Optogenetics has revolutionized neuroscience. It has allowed researchers to identify which neurons are involved in memory, sleep, movement, and fear. But its impact extends far beyond the laboratory. Clinical trials are already underway attempting to restore partial vision in people with degenerative retinal diseases by making surviving cells light-sensitive. Researchers are also exploring applications for treating Parkinson’s disease and epilepsy.
It serves as a prime example of how basic scientific research, even on algae, can transform medicine.
MS
