Mima mound mystery

The mystery of one of the strangest landscape features on the planet - Mima mounds - has been solved, scientists say. These geological anomalies are circular hillocks that cover great swathes of land. But scientists have been puzzled about what causes them.

Now new research suggests that tiny burrowing animals are their architects.

The findings will be presented at the American Geophysical Union Fall Meeting in San Francisco. Mima mounds, which measure up to 7 feet in height and 160 feet in diameter, are found all around the world. However, they are most common in North America.

In some areas, they can number in millions, stretching for many kilometres across the landscape.

Lead researcher Manny Gabet, of San Jose State University, told BBC News: “The big mystery surrounding Mima mounds is that, until now, nobody really knew how they formed. “Over the past couple of hundred years, people thought they might be Native American burial mounds, or they were caused by earthquakes or glaciers. Some people even suggested extraterrestrials.”

Now, though, Gabet says he is certain that gophers have created the mysterious mounds. Using a computer program, the researchers analysed how the rodents move soil as they burrow. They found that in areas prone to waterlogging, the gophers gradually shift tiny amounts of earth upwards to try to stay dry.

Over hundreds of years, though, as many generations of gophers repeat this process, these minute piles of soil grow into the large structures.

But gophers are only found in America, while Mima mounds are found in every continent apart from Antarctica.

Rebecca Morelle

Cancer vaccines

A highly personalised medical technique is allowing patients with advanced kidney cancer to live nearly three times as long as they normally do. In an experiment involving 21 patients, around half lived more than two-and-a-half years after diagnosis with kidney cancer that had begun to spread. Five patients are alive after more than five years.

“That seems to be out of proportion with what you would expect for any commercial therapy and longer than what you would expect from patients with similar prognostic variables,” says Robert Figlin, an oncologist at Cedars-Sinai Samuel Oschin Comprehensive Cancer Institute in Los Angeles, who is leading the study.

The findings are part of a large wave of positive results coming from a class of oncology treatments called cancer immunotherapies. Many drug companies, large and small, are working on treatments that instigate the immune system to attack cancer.

There are a variety of methods for revving up immune cells. In some cases, like the experimental kidney cancer treatment, doctors train a patient’s own white blood cells to spot a cancer cell among its harmless neighbors.

Most so-called cancer vaccines are off-the-shelf products that teach immune cells to attack cancer cells bearing a particular protein. Since cancer is known for its tendency to mutate, these off-the-shelf treatments “may be targeting something that doesn’t exist in each patient,” says Jeff Abbey, CEO of Argos Therapeutics, Durham, North Carolina, a biotech firm that developed the kidney cancer treatment. “Argos is taking a more personalised approach.

“We think that the only way to win is to do an active specific immunotherapy that captures all the mutations,” Abbey says.

Argos’ therapy begins with a piece of a tumour removed in cancer surgery. From that bit of biological material, scientists at the company extract RNA, the molecular cousin of DNA, which represents all active genes in the tumour cells. The collection of active genes then becomes a vaccine for the patient’s immune system. Two or three weeks after the cancer surgery, doctors collect white blood cells from the patient in a process similar to blood donation.

Those immune system cells then get shipped to Argos, which modifies them with the tumour genes and some chemicals so that they learn to target the mutations found specifically in a patient’s own cancer cells. The cells then alert other immune system cells to attack the cancer.

Susan Young Rojahn