Week in Review: August 10–14

Irisin in human blood; engineered yeast produce opioids; Lyme disease–causing bacteria persist in vitro; understanding the malaria-cancer link

Aug 14, 2015
Tracy Vence

Mass spec data: irisin is real

FLICKR, JOSIAH MACKENZIEThe team that first identified irisin—a fat-browning protein commonly called “the exercise hormone”—has again provided evidence that it circulates in human blood and is released following physical activity. In a Cell Metabolism paper published this week (August 13), Harvard Medical School’s Bruce Spiegelman and his colleagues used tandem mass spectrometry to show that irisin—the subject of much debate this year—exists.

“There is no next level of analysis,” Spiegelman told The Scientist. “This is down to, literally, the atomic level.”

“Using state-of-the-art mass spectrometry, the authors show irisin in circulation—the strongest evidence for irisin in humans,” said Sven Enerbäck of Gothenburg University in Sweden who was not involved in the work. “The field can now turn to evaluating the effects of irisin on human physiology.”

Producing opioids with engineered yeast

STEPHANIE GALANIEStanford University’s Christina Smolke and her colleagues have fully re-engineered the biosynthetic pathway that turns a sugar into an opioid precursor in the yeast Saccharomyces cerevisiae. Their results were published in Science this week (August 13).

“It’s the first time an entire pathway from sugar to morphinans has been stitched together,” said Ian Graham, a geneticist at the University of York, U.K., who was not involved in the study.

To create its engineered yeast, the researchers used nearly two dozen enzymes from plants, mammals, bacteria, and yeast to convert a sugar into thebaine, which can be converted into codeine and oxycodone. Much work remains before the production process can be executed on a commercial scale, however.

“If they’re going to take this to a commercial level, you’re going to have strains that are producing high levels of these molecules,” said Vincent Martin of Concordia University in Montreal who was not involved in the work.

Borrelia burgdorferi persisters in vitro

CDC; JAMICE HANEY CARR, CLAUDIA MOLINSBorrelia burgdorferi, the bacteria that cause Lyme disease, can persist through certain antibiotic treatments in culture, even if they are sensitive to the drugs, scientists have recently shown. The existence of such persisters may interfere with the host immune system.

When it comes to Lyme disease research, “there’s a whole new interest in what are called viable but non-cultivable bacteria,” said Monica Embers of Tulane University in New Orleans.

After finding evidence to suggest B. burgdorferi can prevent long-term immunological memory in mice, researchers are now investigating whether it might have similar effects in humans.

“It’s really important to do this work in vitro,” Embers told The Scientist. “But what we’d like to see is a shift to looking in vivo.”

Understanding the malaria-lymphoma link

FLICKR, ED ETHMANActivation-induced cytosine deaminase (AID), an enzyme that helps protect against malaria and other infectious diseases, may cause DNA damage that makes people who are exposed to the parasite more susceptible to a type of lymphoma, researchers from New York City’s Rockefeller University and their colleagues showed in a mouse model this week (August 13).

“This has been a key question in the field for a long time: What’s the role of malaria in promoting Burkitt’s lymphoma?” said Rosemary Rochford of the University of Colorado, Denver, who was not involved in the work.

“AID is not a very precise enzyme,” said study coauthor Davide Robbiani of Rockefeller. “It not only does its physiological job, it attacks other regions of DNA in the genome and causes DNA breaks and translocations,” which might increase one’s risk of developing a certain cancer.

Collaborations can boost citations

ISTOCK, LUCATOLong-term collaborations can increase the number of citations a given coauthored paper receives by around 17 percent, according to an analysis by Alexander Petersen of Italy’s IMT Institute for Advanced Studies Lucca published in PNAS this week (August 10).

This finding “supports what people have suspected for a long time, but never been able to demonstrate well,” said Joseph Loscalzo of the Brigham and Women’s Hospital in Boston who was not involved with the research

Other news in life science:

Fruit-Fly Neurons in Action
Researchers visualize the complete nervous system of a Drosophila melanogaster larva at nearly single-neuron resolution.

Doctor Who Blocked Thalidomide Dies
Frances Oldham Kelsey, a physician who halted use of a drug that caused birth defects in babies, has passed away at age 101.

Esteemed Cancer Surgeon Dies
Carolyn Kaelin, a breast cancer surgeon, survivor, and advocate has passed away at age 54.

Scotland Nixing GM Crops
The country will opt-out of growing genetically modified foods that have been approved for cultivation in the European Union.

Pupil Alignment of Predators and Prey
Ambush predators are more likely to have vertical slit pupils, while foraging animals tend to have horizontal ones, a study shows.