Old blood can prematurely age the brains of young mice, and scientists may now be closer to understanding how. A protein located in the cells that form a barrier between the brain and blood could be partly to blame, experiments on mice suggest.
If something similar happens in humans, scientists say, methods for countering the protein may hold promise for treating age-related brain decline.
The preliminary study, published online January 3 at bioRxiv.org, focused on a form of the protein known as VCAM1, which interacts with immune cells in response to inflammation. As mice and humans age, levels of that protein circulating in the blood rise, Alzheimer researcher Tony Wyss-Coray at Stanford University and colleagues found. After injecting young mice behind an eye with plasma from old mice, the team discovered that VCAM1 levels also rose in certain parts of the blood-brain barrier, a mesh of tightly woven cells that protect the brain from harmful factors in the blood. The young mice showed signs of brain deterioration as well, including inflammation and decreased birthrates of new nerve cells. Plasma from young mice had no such effects.
Interfering with VCAM1 may help prevent the premature aging of brains. Plasma from old mice didn’t have a strong effect when injected into young mice genetically engineered to lack VCAM1 in certain blood-brain barrier cells. Nor did it affect mice treated with antibodies that blocked the activity of VCAM1. Those antibodies also seemed to help the brains of older mice that had aged naturally, the team found.
The results suggest that anti-aging treatments targeting specific aspects of the blood-brain barrier may hold promise.
These fins were made for walking, and that’s just what these fish do — thanks to wiring that evolved long before vertebrates set foot on land.
Little skates use two footlike fins on their undersides to move along the ocean floor. With an alternating left-right stride powered by muscles flexing and extending, the movement of these fish looks a lot like that of many land-based animals.
Now, genetic tests show why: Little skates and land vertebrates share the same genetic blueprint for development of the nerve cells needed for limb movement, researchers report online February 8 in Cell. This work is the first to look at the origins of the neural circuitry needed for walking, the authors say. “This is fantastically interesting natural history,” says Ted Daeschler, a vertebrate paleontologist at the Academy of Natural Sciences in Philadelphia.
“Neurons essential for us to walk originated in ancient fish species,” says Jeremy Dasen, a neuroscientist at New York University. Based on fossil records, Dasen’s team estimates that the common ancestor of all land vertebrates and skates lived around 420 million years ago — perhaps tens of millions of years before vertebrates moved onto land (SN: 1/14/12, p. 12). Little skates (Leucoraja erinacea) belong to an evolutionarily primitive group. Skates haven’t changed much since their ancestors split from the fish that evolved into land-rovers, so finding the same neural circuitry in skates and land vertebrates was surprising.
The path to discovery started when Dasen and coauthor Heekyung Jung, now at Stanford University, saw YouTube videos of the little skates walking.
“I was completely flabbergasted,” Dasen says. “I knew some species of fish could walk, but I didn’t know about these.”
Most fish swim by undulating their bodies and tails, but little skates have a spine that remains relatively straight. Instead, little skates move by flapping pancake-shaped pectoral fins and walking on “feet,” two fins tucked along the pelvis.
Measurements of the little skates’ movements found that they were “strikingly similar” to bipedal walking, says Jung, who did the work while at NYU. To investigate how that similarity arose, the researchers looked to motor nerve cells, which are responsible for controlling muscles. Each kind of movement requires different kinds of motor nerve cells, Dasen says.
The building of that neural circuitry is controlled in part by Hox genes, which help set the body plan, where limbs and muscles and nerves should go. For instance, snakes and other animals that have lost some Hox genes have bodies that move in the slinky, slithery undulations that many fish use to swim underwater.
By comparing Hox genes in L. erinacea and mice, researchers discovered that both have Hox6/7 and Hox10 genes and that these genes have similar roles in both. Hox6/7 is important for the development of the neural circuitry used to move the skates’ pectoral fins and the mice’s front legs; Hox10 plays the same role for the footlike fins in little skates and hind limbs in mice. Other genes and neural circuitry for motor control were also conserved, or unchanged, between little skates and mice. The findings suggest that both skates and mice share a common ancestor with similar genetics for locomotion.
The takeaway is that “vertebrates are all very similar to each other,” says Daeschler. “Evolution works by tinkering. We’re all using what we inherited — a tinkered version of circuitry that began 400-plus million years ago.”
Orangutan numbers on the Southeast Asian island of Borneo plummeted from 1999 to 2015, more as a result of human hunting than habitat loss, an international research team finds.
Over those 16 years, Borneo’s orangutan population declined by about 148,500 individuals. A majority of those losses occurred in the intact or selectively logged forests where most orangutans live, primatologist Maria Voigt of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, and colleagues report February 15 in Current Biology. “Orangutan killing is likely the number one threat to orangutans,” says study coauthor Serge Wich, a biologist and ecologist at Liverpool John Moores University in England. Humans hunt the forest-dwelling apes for food, or to prevent them from raiding crops, the investigators say. People also kill adult orangutans to steal their babies for the international pet trade.
Between 70,000 and roughly 100,000 orangutans currently live on Borneo, Wich says. That’s substantially higher than previous population estimates. The new figures are based on the most extensive survey to date, using ground and air monitoring of orangutans’ tree nests. Orangutans live only on Borneo and the island of Sumatra and are endangered in both places.
Still, smaller orangutan populations in deforested areas of Borneo — due to logging or conversion to farm land — experienced the severest rates of decline, up to a 75 percent drop in one region.
Satellite data indicate that Borneo’s forest area has already declined by about 30 percent from 1973 to 2010. In the next 35 years, Voigt’s team calculates that further habitat destruction alone will lead to the loss of around 45,000 more of these apes. “Add hunting to that and it’s a lethal mix,” Wich says. But small groups of Bornean orangutans living in protected zones and selectively logged areas will likely avoid extinction, the researchers say.
While the drama of human heart transplants has grasped the public interest, kidney transplants are ahead in the field…. Although only three little girls are now surviving liver transplants, the liver is a promising field for replacement…. The donor, of course, must be dead; no one can live without his liver. — Science News, March 2, 1968
Update Kidney patients, who could receive organs from family members, had up to a 75 percent one-year survival rate in 1968. Liver recipients were less lucky, having to rely on unrelated, postmortem donations. Liver patients’ immune systems often attacked the new organ and one-year survival was a low 30 percent. Cyclosporine, an immune-suppressing drug available since 1983, has made a big difference. Now, about 75 percent of adults are alive three years after surgery, and children’s odds are even better. The liver is still a must-have organ, and the need for donor livers has climbed. Today, the options have expanded, with split-liver transplants and partial transplants from living donors.
