Here are some stem cell stories that caught our eye this past week. Some are groundbreaking science, others are of personal interest to us, and still others are just fun.

Which fat for you, white, brown or beige. Those who read up on those pesky fat cells that accumulate in our bodies probably have heard about white fat and brown fat. White is the bad guy linked to obesity and diabetes and brown is the good guy that burns energy and fosters leanness. Add one more color. A team at the University of California, San Francisco, has isolated beige fat that can convert white to brown.

They now want to see if they can figure out the molecular mechanism behind this conversion to see if they can develop a therapy to combat obesity. I heard a presentation on similar work at the International Society for Stem Cell Research last June, and there were suggestions that the stem cell known to reside in fat may play a role, but no one seems to be sure.

The current research made it into Nature Medicine and ScienceDaily picked up the university’s press release, which quotes the senior researcher, Shingo Kajimura:

“This finding brings us another step closer to the goal of our laboratory, which is engineering fat cells to fight obesity. We are trying to learn how to convert white fat into brown fat, and until now, it had not been demonstrated that this recruitable form of brown fat is actually present in humans.”

A wonkish revelation on reprogrammed stem cells. When Shinya Yamanaka first discovered how to reprogram adult cells into embryonic-like stem cells, the resulting iPS cells won him the Nobel Prize. But neither he nor anyone else knew exactly how this reprogramming actually happened. It was assumed that by adding genes that are normally only active during embryo development we were turning back the clock and letting the cells sort of start over.

Now, CIRM-funded researchers at Stanford have discovered the cells first go through a clearly identifiable intermediate state that does not have any of the markers of early stem cells, so called pluripotency genes. The leader of the team, Marius Wernig, described his surprise in a university press release picked up by HealthCanal:

“This was completely unexpected. It’s always been assumed that reprogramming is simply a matter of pushing mature cells backward along the developmental pathway. These cells would undergo two major changes: They’d turn off genes corresponding to their original identity, and begin to express pluripotency genes. Now we know there’s an intermediary state we’d never imagined before.”

The research, published in Nature, used a clever new technique that lets cells grow in individual tiny wells on a laboratory plate. Wernig hopes the finding will help his group and others find ways to improve reprogramming efficiency, which is commonly in single percentage points and rarely in the teens.

Chemical trick yields nerves needed in Parkinson’s. It’s relatively easy to get stem cells to mature into nerves, but can be quite difficult sometimes to get them to grow into just the right kind of nerves. The dopamine-producing nerves needed in Parkinson’s disease turn out to be one of the difficult ones.

Now, a team from Brazil has used an approved drug to treat stem cells in the lab and get them to consistently mature into dopamine-producing nerves. What’s better, the cells survived and continued to produce dopamine for 15 months after being transplanted into mice. ScienceDaily picked up the press release from D’Or Institute for Research and Education.

The X chromosome and disease? Researchers have long sought answers to why when a disease gene resides on the X chromosome, it often causes more harm in boys than girls. A likely culprit is the process a developing embryo uses to shut down one of the two X chromosomes in females, and a team at Stanford thinks they have found a way to discover how.

The CIRM-funded team lead by Howard Chang used a new molecular tool to study in detail all the components of the cell involved in silencing one of the X chromosomes.

Researchers have known for some time that one particular genetic component, an RNA called Xist, plays a lead role. But Chang’s team discovered 80 different proteins it interacts with in order to completely shut down one X chromosome. They hope that learning more about the process will let researchers figure out how this selective silencing protects females from some of the mutations on the X chromosome.

The Stanford press release, picked up by HealthCanal, starts with a fun explanation of X silencing and how it can lead to calico female cats, but not males—sorry Garfield you don’t exist.