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Week in Review: May 12–16

Antidepressant could prevent Alzheimer’s plaques; 12,000-year-old human skeleton sequenced; disentangling the mystery of octopus arms; taking a look at the ocular microbiome

By | May 16, 2014

Ancient human skeleton analyzed

PAUL NICKLEN/NATIONAL GEOGRAPICDNA sequences extracted from the bones and teeth of “Naia”—a girl thought to be 15- or 16-years-old when she died around 12,000 years ago—is helping researchers to better understand when and how humans populated the Americas. This week (May 15) in Science, Washington-based archaeologist and paleontologist James Chatters and his colleagues published their morphological and genetic analyses of the ancient human, found by divers in an underwater cave near Mexico in 2007.

“With this specimen, we have evidence that the physical differences between the ancient and modern Americans came about through evolution that occurred after the Beringia migration,” said Chatters, refuting the notion that humans arrived to North America through multiple migrations from different parts of Asia and Europe.

“This girl’s maternal ancestry traces to the same source population as that of modern Native Americans,” molecular anthropologist Deborah Bolnick from the University of Texas at Austin told The Scientist.

Naia joins “Anzick-1,” a young boy uncovered in Montana who researchers described this February in Nature, among the five oldest North American humans to have been found and genetically analyzed.

SSRI shows promise for Alzheimer’s

WIKIPEDIA, NEPHRONA small clinical trial published in Science Translational Medicine this week (May 14) suggested that the selective serotonin reuptake inhibitor (SSRI) citalopram, which is commonly prescribed to treat depression among other things, could help stave off the formation of Alzheimer’s disease-associated amyloid plaques. Yvette Sheline from the University of Pennsylvania and her colleagues also studied the effects of citalopram in mice.

“Every SSRI we have tested in mouse models has the same effect on lowering amyloid concentrations,” Sheline wrote in an e-mail to The Scientist.

But it’s the human results, from a trial involving 28 healthy participants who were 18 to 50 years old, are catching the attention of the scientific community. “Citalopram is now added to the list of medications that have such effects on amyloid and therefore make it a consideration for prevention trials of Alzheimer’s disease,” said Constantine Lyketsos, who directs the Alzheimer’s and Memory Center at Johns Hopkins School of Medicine and was not involved in the work. However, he cautioned in an e-mail, “the main hypothesis that reducing amyloid production reduces Alzheimer’s disease incidence is unproven.” 

Infanticide kill-switch neurons

WIKIMEDIA, HIPPOCAMPUSHarvard University’s Catherine Dulac and her colleagues have homed in on a population of neurons, called galanin neurons, in the medial preoptic area of the mouse brain that seem to help mediate the behavioral switch in adult mice that causes them to care for pups, rather than eat them. Their work was published in Nature this week (May 14).

“So the interesting question [is] whether there are specific mechanisms to suppress one [set of behaviors] and allow the other,” said C. Ron Yu from the Stowers Institute for Medical Research in Kansas City, Missouri, who was not involved in the work.

Octopus arms recognize limbs as self

WIKIMEDIA, H. ZELLMembers of the Octopus Research Group at The Hebrew University of Jerusalem have helped to disentangle a long-standing mystery in marine biology and neuroscience this week (May 15), when they reported in Current Biology on a self-recognition mechanism that helps prevent the eight-armed cephalopods from becoming tied up in knots.

“About two-thirds of the octopus’ nervous system is in the arms. The local nervous system of the arms locally analyzes sensory information and sends ‘conclusions’ to the brain,” said study coauthor Guy Levy. The researchers proposed that a chemical secreted by octopus skin is what sends self- versus non-self-recognition signals to the brain, pointing to one reason why the cephalopods don’t eat their own limbs, which are often amputated naturally in the wild, the authors said.

Other news in life science:

Visualizing the Ocular Microbiome
Researchers are beginning to study in depth the largely uncharted territory of the eye’s microbial composition.

WHO: MERS as Global Health Threat?
A World Health Organization committee finds no evidence of sustained human-to-human transmission of the deadly coronavirus, but recommends immediate action to prevent further spread.

NIH to Close Sex Gap in Preclinical Research
The funding agency will require grant applicants to address sex balance in all future cell and animal studies.

Diseased Heart Chip
In the latest iteration of organ-on-a-chip technology, researchers develop an in vitro model of functioning human heart tissue with an inherited cardiovascular disease.

Minding Research Ethics
The Presidential Commission for the Study of Bioethical Issues advises the integration of ethics into research on the human brain.

Metabolism Mapped
Researchers unveil the most comprehensive atlas of genes underlying human metabolic pathways, paving the way for improved understanding and treatment of metabolic diseases.

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