Genetic Study Confirms that the First Dogs Came from East Asia

Researchers at Sweden's KTH Royal Institute of Technology say they have found further proof that the wolf ancestors of today's domesticated dogs can be traced to southern East Asia 
Wednesday, 23 November 2011

Researchers at Sweden's KTH Royal Institute of Technology say they have found further proof that the wolf ancestors of today's domesticated dogs can be traced to southern East Asia – findings that run counter to theories placing the cradle of the canine line in the Middle East.

Dr Peter Savolainen, KTH researcher in evolutionary genetics, says a new study released Nov. 23 confirms that an Asian region south of the Yangtze River was the principal and probably sole region where wolves were domesticated by humans.

Data on genetics, morphology and behaviour show clearly that dogs are descended from wolves, but there's never been scientific consensus on where in the world the domestication process began.

"Our analysis of Y-chromosomal DNA now confirms that wolves were first domesticated in Asia south of Yangtze River – we call it the ASY region – in southern China or Southeast Asia", Savolainen says.

The Y data supports previous evidence from mitochondrial DNA.

"Taken together, the two studies provide very strong evidence that dogs originated in the ASY region", Savolainen says.

Archaeological data and a genetic study recently published in Nature suggest that dogs originate from the Middle East. But Savolainen rejects that view.

"Because none of these studies included samples from the ASY region, evidence from ASY has been overlooked," he says.

Peter Savolainen and PhD student Mattias Oskarsson worked with Chinese colleagues to analyse DNA from male dogs around the world. Their study was published in the scientific journal Heredity.

Approximately half of the gene pool was universally shared everywhere in the world, while only the ASY region had the entire range of genetic diversity.

"This shows that gene pools in all other regions of the world most probably originate from the ASY region", Savolainen says.

"Our results confirm that Asia south of the Yangtze River was the most important – and probably the only – region for wolf domestication, and that a large number of wolves were domesticated", says Savolainen.

In separate research published recently in Ecology and Evolution, Savolainen, PhD student Arman Ardalan and Iranian and Turkish scientists conducted a comprehensive study of mitochondrial DNA , with a particular focus on the Middle East. Because mitochondrial DNA is inherited only from the mother in most species, it is especially useful in studying evolutionary relationships.

"Since other studies have indicated that wolves were domesticated in the Middle East, we wanted to be sure nothing had been missed. We find no signs whatsoever that dogs originated there", says Savolainen.

In their studies, the researchers also found minor genetic contributions from crossbreeding between dogs and wolves in other geographic regions, including the Middle East.

"This subsequent dog/wolf hybridisation contributed only modestly to the dog gene pool", Savolainen explains.

Source: Swedish Research Council

Contact: Katarina Ahlfort
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Lab Creates Cells Used by Brain to Control Muscle Cells

Lab Creates Cells Used by Brain to Control Muscle Cells
Tuesday, 22 November 2011

 University of Central Florida researchers, for the first time, have used stem cells to grow neuromuscular junctions between human muscle cells and human spinal cord cells, the key connectors used by the brain to communicate and control muscles in the body.

Dr. Hickman has been working on this

project for more than a decade.

Credit: University of Central Florida.

The success at UCF is a critical step in developing "human-on-a-chip" systems. The systems are models that recreate how organs or a series of organs function in the body. Their use could accelerate medical research and drug testing, potentially delivering life-saving breakthroughs much more quickly than the typical 10-year trajectory most drugs take now to get through animal and patient trials.

"These types of systems have to be developed if you ever want to get to a human-on-a-chip that recreates human function," said James Hickman, a UCF bioengineer who led the breakthrough research.

"It's taken many trials over a number of years to get this to occur using human derived stem cells."

Hickman's work, funded through the National Institute of Neurological Disorders and Stroke (NINDS) at the National Institutes of Health, is described in the December issue of Biomaterials.

Hickman is excited about the future of his research because several federal agencies recently launched an ambitious plan to jump-start research in "human-on-a-chip" models by making available at least $140 million in grant funding.

The National Institutes of Health (NIH), the Defense Advanced Research Projects Agency (DARPA), and the Federal Drug Administration (FDA) are leading the research push.

The goal of the call for action is to produce systems that include various miniature organs connected in realistic ways to simulate human body function. This would make it possible, for instance, to test drugs on human cells well before they could safely and ethically be tested on living humans. The technique could potentially be more effective than testing in mice and other animals currently used to screen promising drug candidates and to develop other medical treatments.

Such conventional animal testing is not only slow and expensive, but often leads to failures that might be overcome with better testing options. The limitations of conventional testing options have dramatically slowed the emergence of new drugs, Hickman said.

The successful UCF technique began with a collaborator, Brown University Professor Emeritus Herman Vandenburgh, who collected muscle stem cells via biopsy from adult volunteers. Stem cells are cells that can, under the right conditions, grow into specific forms. They can be found among normal cells in adults, as well as in developing fetuses.

Nadine Guo, a UCF research professor, conducted a series of experiments and found that numerous conditions had to come together just right to make the muscle and spinal cord cells "happy" enough to join and form working junctions. This meant exploring different concentrations of cells and various timescales, among other parameters, before hitting on the right conditions.

"Right now we rely a lot on animal systems for medical research but this is a pure human system," Guo said.

"This work proved that, biologically, this is workable."

Besides being a key requirement for any complete human-on-a-chip model, such nerve-muscle junctions might themselves prove important research tools. These junctions play key roles in Amyotrophic lateral sclerosis, commonly known as Lou Gehrig's disease, in spinal cord injury, and in other debilitating or life threatening conditions. With further development, the team's techniques could be used to test new drugs or other treatments for these conditions even before more expansive chip-based models are developed.

Source: University of Central Florida

Contact: Barbara Abney
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Researchers Turn Embryonic Stem Cells into Functioning Neurons

Implanted neurons, grown in the lab, take charge of brain circuitry 
Tuesday, 22 November 2011

Among the many hurdles to be cleared before human embryonic stem cells can achieve their therapeutic potential is determining whether or not transplanted cells can functionally integrate into target organs or tissues.

Writing today (Monday, Nov. 21) in the Proceedings of the National Academy of Sciences, a team of Wisconsin scientists reports that neurons, forged in the lab from blank slate human embryonic stem cells and implanted into the brains of mice, can successfully fuse with the brain's wiring and both send and receive signals.

Neurons are specialized, impulse conducting cells that are the most elementary functional unit of the central nervous system. The 100 billion or so neurons in the human brain are constantly sending and receiving the signals that govern everything from walking and talking to thinking. The work represents a crucial step toward deploying customized cells to repair damaged or diseased brains, the most complex human organ.

"The big question was can these cells integrate in a functional way," says Jason P. Weick, the lead author of the new study and a staff scientist at the University of Wisconsin-Madison's Waisman Center.

"We show for the first time that these transplanted cells can both listen and talk to surrounding neurons of the adult brain."

The Wisconsin team tested the ability of their lab grown neurons to integrate into the brain's circuitry by transplanting the cells into the adult mouse hippocampus, a well-studied region of the brain that plays a key role in processing memory and spatial navigation. The capacity of the cells to integrate was observed in live tissue taken from the animals that received the cell transplants.

Weick and colleagues also reported that the human neurons adopted the rhythmic firing behavior of many brain cells talking to one another in unison. And, perhaps more importantly, that the human cells could modify the way the neural network behaved.

A critical tool that allowed the UW group to answer this question was a new technology known as optogenetics, where light, instead of electric current, is used to stimulate the activity of the neurons.

"Previously, we've been limited in how efficiently we could stimulate transplanted cells. Now we have a tool that allows us to specifically stimulate only the transplanted human cells, and lots of them at once in a non-invasive way," says Weick.

Weick explains that the capacity to modulate the implanted cells was a necessary step in determining the function of implanted cells because previous technologies were too imprecise and unreliable to accurately determine what transplanted neurons were doing.

Embryonic stem cells, and the closely related induced pluripotent stem cells can give rise to all of the 220 types of tissues in the human body, and have been directed in the lab to become many types of cells, including brain cells.

The appeal of human embryonic stem cells and induced pluripotent cells is the potential to manufacture limitless supplies of healthy, specialized cells to replace diseased or damaged cells. Brain disorders such as Parkinson's disease and amyotrophic lateral sclerosis, more widely known as Lou Gehrig's disease, are conditions that scientists think may be alleviated by using healthy lab grown cells to replace faulty ones. Multiple studies over the past decade have shown that both embryonic stem cells and induced cells can alleviate deficits of these disorders in animal models.

The new study opens the door to the potential for clinicians to deploy light-based stimulation technology to manipulate transplanted tissue and cells.

"The marriage between stem cells and optogenetics has the potential to assist in the treatment of a number of debilitating neurodegenerative disorders," notes Su-Chun Zhang, a UW-Madison professor of neuroscience and one of the authors of the new PNAS report.

"You can imagine that if the transplanted cells don't behave as they should, you could use this system to modulate them using light."

Source: University of Wisconsin-Madison

Contact: Jason P. Weick

Reference:

Human embryonic stem cell-derived neurons adopt and regulate the activity of an established neural network
Jason P. Weick, Yan Liu, and Su-Chun Zhang
Proceedings of the National Academy of Sciences, November 21, 2011, doi:10.1073/pnas.1108487108
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