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Using bacteriophages to deliver a specific CRISPR/Cas system into antibiotic-resistant bacteria can sensitize the microbes to the drugs, according to a study published this week (May 18) in PNAS.

Current CRISPR-based screens often mutate the beginning of a gene, which sometimes results in the expression of a functional protein variant. To circumvent this problem, researchers at Cold Spring Harbor Laboratory (CSHL) designed CRISPR guide RNAs that would mutate the portion of a gene encoding a domain on the surface of the protein where a small molecule could bind to alter the protein's function. The team had previously identified such a binding pocket on the protein BRD4, and a small molecule inhibitor that binds in the pocket is an effective leukemia treatment.

Exposing mice to long periods of light each day led them to put on fat, likely because their energy-burning brown fat wasn't in good shape.  Mice exposed to long periods of light didn't eat more or exercise less than mice that kept to a 12-hour day, but their brown fat activity dropped, researchers reported in PNAS this week (May 11).

Researchers at the University of Pennsylvania performed "stress tests" on pregnant mice using a predator's odor, restraint, or unfamiliar noises. After the mice gave birth, the scientists analyzed the bacterial communities in their vaginas and in their pups' colons. The researchers found that stress during pregnancy altered the expression levels of several proteins involved in vaginal immunity and the frequency of Lactobacillus bacteria, which, expectedly, correlated to lower frequencies of Lactobacillus within their pups' gut microbiomes. Male pups of stressed mothers also displayed an increase in anaerobic bacteria like Clostridium and Bacteroidesin.

Genetic differences among ethnically diverse individuals are largely due to structural elements called copy number variants (CNVs), according to a study published today (August 6) in Science. Compared with other genomic features, such as single nucleotide variants (SNVs), CNVs have not previously been studied in as much detail because they are more difficult to sequence. Covering 125 distinct human populations around the world, geneticist Evan Eichler at the University of Washington in Seattle and an international team of colleagues studied the genomes of 236 people-analyzing both SNVs and CNVs. "The take-home message is that we continue to find a lot more genetic variation between humans than we appreciated previously," Eichler told The Scientist.

Nat Geo video 2 min facts and graphics

Unexpected discoveries in the quest to cure an extraordinary skeletal condition show how medically relevant rare diseases can be.

Cattle with the mouse gene SP110 added to their genomes have immune cells that are better at slowing the growth of Mycobacterium bovis and are less susceptible to developing the internal symptoms of tuberculosis (TB), according to a study published this week (March 2) in PNAS.

Aneuploidy-the incorrect number of chromosomes in a cell-is extremely common in early embryos and is the primary reason for pregnancy loss. A report published today (April 9) in Science reveals that one cause of this aneuploidy-aberrant cell divisions in the embryo-is linked to a genetic mutation carried by the mother. Astonishingly, this mutation turns out to be very common and appears to have been under positive selection during human evolution.

These case studies heralded a new appreciation for the phenomenon of genetic chimerism-when an individual carries two or more genetically distinct cell lines in different parts of her body. Until the advent of techniques for blood typing and karyotyping cells, genetic chimeras where thought to be very rare. They only came to light when the phenotypes associated with the two distinct genomes were so discordant that the resulting individual was clearly exceptional, with patches of distinct skin coloration throughout the body, for example, or hermaphroditic genitals. In reality, genetic chimeras may be quite common, disguised in perfectly normal bodies harboring genetically distinct cell lineages.

In our view, and that of organizations such as the American Society of Clinical Oncology, the World Cancer Research Fund International, and the American Cancer Society, obesity-related cancers will arguably be the most urgent issue in the cancer field in the next decade.

Some 20 percent of cancer-related deaths in the U.S. can be attributed to obesity, making it the number-one preventable cause of cancer death in the country. But with myriad metabolic and inflammatory changes associated with obesity, determining the mechanisms that underlie the obesity-cancer link has proven challenging.

Now a study of 15 Finnish families, published in the Journal of Medical Genetics, provides the first proof that musical ability is indeed linked to genes.

Not surprisingly, Hambrick and Tucker-Drob found a correlation between practice and musical accomplishment. But they also found that the amount of practice young musicians engaged in was influenced by their genetic make-up.

Stress is implicated in increased tumor progression risk and poor survival in cancer patients. A number of recent studies have linked these effects to the promotion of tumor cell dissemination through the bloodstream via stress-induced pathways. Now, a mouse study led by researchers in Australia has revealed the mechanisms by which stress modulates cancer's spread through another transport network open to tumor cells-the lymphatic system.

"Millions of people who suffer from less-intense sleep problems do suffer myriad health burdens. In addition to emotional distress and cognitive impairments, these can include high blood pressure, obesity, and metabolic syndrome. And recent research has suggested even mild sleep loss, the kind people often subject themselves to during the work week by watching late-night TV until midnight then rising before dawn, may lead to metabolic, cardiovascular, cognitive, and neurologic dysfunction."

More than 400 scientists, bioethicists, and historians from 20 countries on 6 continents have gathered this week in Washington, DC, for the Human Gene Editing Summit. The attendees are a veritable who's who of genome editing: Jennifer Doudna of the University of California, Berkeley, Emmanuelle Charpentier of Max Planck Institute for Infection Biology, and Feng Zhang of the Broad Institute of MIT and Harvard-the three discoverers of the CRISPR-Cas9 system's utility in gene editing-plus dozens of other big names in genome science. Cal Tech's David Baltimore along with the heads of the four national societies hosting the meeting (US National Academy of Sciences, US National Academy of Medicine, Chinese Academy of Sciences, and the U.K.'s Royal Society) provided opening remarks on Tuesday (December 1). And as I sat stage right in the NAS auditorium, I noticed the unmistakable rear profile of Harvard Medical School's George Church three rows in front of me. Church was scheduled to speak at a session later that afternoon about the application of CRISPR and other new precision gene editing techniques to the human germline-a hot-button topic since April, when a Chinese group published it had successfully modified the genomes of human embryos, and the National Institutes of Health (NIH) said it would not fund such research. Then in September, the U.S./U.K.-based Hinxton Group, an international consortium of scientists, policy experts, and bioethicists, said it supported the use of genetic editing in human embryos for limited applications in research and medicine.  

Why elephants aren't riddled with tumors poses a weighty problem for researchers. A new study shows that the animals harbor dozens of extra copies of one of the most powerful cancer-preventing genes. These bonus genes might enable elephants to weed out potentially cancerous cells before they can grow into tumors.

This biomarker, called the KRAS-variant, is linked to more cancers than any other known inherited genetic mutation. It is present in 1 out of every 4 people with cancer, and in more than half of people who develop multiple cancers. KRAS-variant carriers tend to get highly aggressive and recurrent breast, ovarian, head and neck, lung and pancreatic cancers.