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Zhen Liu et al. in Nature

Scientists Genetically Engineer Autistic Monkeys

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Zhen Liu et al. in Nature

Scientists in China have genetically altered monkeys to have a human gene associated with autism spectrum disorders. As a result, the monkeys show a range of symptoms associated with autism. Their findings were published today in the journal Nature.

Mutations of methyl-CpG binding protein 2 (MECP2) are found in 90 percent of patients with Rett syndrome, a severe developmental disorder affecting mostly girls that is classified as an autism spectrum disorder. MECP2 duplication syndrome, in which a person has multiple copies of the gene, also shares core symptoms with autism spectrum disorders. It mostly affects boys. The researchers inserted the MECP2 gene into oocytes, or egg cells, of Macaca fascicularis (known variously as the crab-eating macaque or cynomolgus monkey). After fertilization, 53 embryos were then transferred into 18 surrogate monkeys. Half became pregnant, and eight offspring were born. 

For the first year the monkeys were developmentally normal, but then issues began to appear. By about 18 months, "the first cohort of transgenic monkeys showed very similar behaviors related to human autism patients, including repetitive behaviors, increased anxiety, and most importantly, defects in social interactions," study co-author Zilong Qiu said in a press-only teleconference on January 21. The monkeys paced in circles around their cages and made a lot of anxious sounds, including grunts and screams. 

The researchers then used an "accelerated reproduction method" to produce a second generation of transgenic monkeys, which also showed defects in social interactions.

This genetic inheritance makes these transgenic monkeys "a very unique model for studying human autism," Qiu said.

Scientists generally use mice to study autism, but there are problems with that approach. For one thing, mice lack an area of the brain known as the prefrontal cortex, which is where some psychiatric disorders appear to be centered, MIT Technology Review notes.

"Mouse models have many advantages, such as low cost, the ability to generate large sample sizes and to carry out extensive pilot work quickly," Melissa Bauman, a researcher at the University of California who specializes in animal models of autism, said in a press statement to Nature. "However, given that Autism Spectrum Disorder (ASD) is [a] uniquely human disorder characterized by deficits in complex behaviors, there are limitations in relying solely on mouse models."

Another researcher cautioned that autism is an incredibly complex disease without a single underlying biological cause. "Some cases of autism do derive from relatively simple genetic events. Mutations in MECP2 and the duplication of MECP2 are only one of these myriad causes," said University of Mississippi Medical Center researcher Eric Vallender in another press statement. Vallender, who studies the neurogenetics of nonhuman primates (NHP), also noted that "repetitive motor behaviors and anxiety-like behaviors can be caused by many things, and 'decreased social interaction' is always tricky to both observe and quantify and to interpret.

"That said," he added, "they have created an excellent model of MECP2 duplication syndrome. This is not trivial and can be a major step forward for understanding neurodevelopmental disorders."

The researchers are currently conducting brain imaging studies of the MECP2 monkeys to try to identify the deficiency in the brain circuits that is responsible for autism-like behavior. Once they identify this brain circuit, they'll attempt to treat the monkeys using various methods, including more genetic modification: "We will use therapeutics, such as gene-editing tools like CRISPR-Cas9 … to explore the potential gene therapy," Qiu said. 

Meanwhile, the creation of transgenic NHPs raises ethical questions, as University of Toronto bioethicist Kerry Bowman told Gizmodo: “Transgenic NHP will potentially exhibit traits that are the most human-like; in turn this puts them at greater risk of research exploitation.”

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Animals
Owning a Dog May Add Years to Your Life, Study Shows
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We've said that having a furry friend can reduce depression, promote better sleep, and encourage more exercise. Now, research has indicated that caring for a canine might actually extend your lifespan.

Previous studies have shown that dog owners have an innate sense of comfort and increased well-being. A new paper published in Scientific Reports and conducted by Uppsala University in Sweden looked at the health records of 3.4 million of the country's residents. These records typically include personal data like marital status and whether the individual owns a pet. Researchers got additional insight from a national dog registry providing ownership information. According to the study, those with a dog for a housemate were less likely to die from cardiovascular disease or any other cause during the study's 12-year duration.

The study included adults 40 to 80 years old, with a mean age of 57. Researchers found that dogs were a positive predictor in health, particularly among singles. Those who had one were 33 percent less likely to die early than those who did not. Authors didn't conclude the exact reason behind the correlation: It could be active people are more likely to own dogs, that dogs promoted more activity, or that psychological factors like lowered incidences of depression might bolster overall well-being. Either way, having a pooch in your life could mean living a longer one.

[h/t Bloomberg]

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Big Questions
Why Don't We Eat Turkey Tails?
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Turkey sandwiches. Turkey soup. Roasted turkey. This year, Americans will consume roughly 245 million birds, with 46 million being prepared and presented on Thanksgiving. What we don’t eat will be repurposed into leftovers.

But there’s one part of the turkey that virtually no family will have on their table: the tail.

Despite our country’s obsession with fattening, dissecting, and searing turkeys, we almost inevitably pass up the fat-infused rear portion. According to Michael Carolan, professor of sociology and associate dean for research at the College for Liberal Arts at Colorado State University, that may have something to do with how Americans have traditionally perceived turkeys. Consumption was rare prior to World War II. When the birds were readily available, there was no demand for the tail because it had never been offered in the first place.

"Tails did and do not fit into what has become our culinary fascination with white meat," Carolan tells Mental Floss. "But also from a marketing [and] processor standpoint, if the consumer was just going to throw the tail away, or will not miss it if it was omitted, [suppliers] saw an opportunity to make additional money."

Indeed, the fact that Americans didn't have a taste for tail didn't prevent the poultry industry from moving on. Tails were being routed to Pacific Island consumers in the 1950s. Rich in protein and fat—a turkey tail is really a gland that produces oil used for grooming—suppliers were able to make use of the unwanted portion. And once consumers were exposed to it, they couldn't get enough.

“By 2007,” according to Carolan, “the average Samoan was consuming more than 44 pounds of turkey tails every year.” Perhaps not coincidentally, Samoans also have alarmingly high obesity rates of 75 percent. In an effort to stave off contributing factors, importing tails to the Islands was banned from 2007 until 2013, when it was argued that doing so violated World Trade Organization rules.

With tradition going hand-in-hand with commerce, poultry suppliers don’t really have a reason to try and change domestic consumer appetites for the tails. In preparing his research into the missing treat, Carolan says he had to search high and low before finally finding a source of tails at a Whole Foods that was about to discard them. "[You] can't expect the food to be accepted if people can't even find the piece!"

Unless the meat industry mounts a major campaign to shift American tastes, Thanksgiving will once again be filled with turkeys missing one of their juicier body parts.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

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