Week in Review: February 2–6

How culturing can change cells; nitrogen-fixing bacterium confirmed; long-lived T memory stem cells; head direction cells support brain’s “inner GPS”

Feb 6, 2015
Tracy Vence

Culture consequence

S. PENNINGS LABTransferring certain mouse cells from their native environment to culture changes them. Specifically, culturing was associated with the loss of the epigenetic mark 5-hydroxymethylcytosine (5hmC) in mouse embryonic fibroblasts, according to a study published in Genome Biology this week (February 3).

In cultured cells, “to our surprise, [5hmC] disappeared almost overnight,” said Medical Research Council’s Richard Meehan, who led the study.

“This paper adds substantial fuel to the fire of concern about using cultured cells to study phenotypes associated with cancer in vivo (such as drug resistance),” the National Cancer Institute’s Michael Gottesman told The Scientist in an e-mail. “Obviously, these studies are done using mouse embryo fibroblasts and not human cancer cells, but the changes in 5hmC levels are so dramatic and so rapid that they cannot be ignored.”

Supporting cells

SHAWN WINTER, BENJAMIN CLARK, DARTMOUTH COLLEGERat grid cells rely in part on cues from head direction cells to function properly, researchers from Dartmouth College showed in Science this week (February 5). When the researchers experimentally impaired connections between the two cell types in the rodents, they found atypical activity.

“The findings are expected but still important in that they verify core ideas of current models of how grid-cell patterns are generated and maintained,” Edvard Moser of the Norwegian University of Science and Technology, who shared the 2014 Nobel Prize in Physiology or Medicine for his work on grid cells, told The Scientist.

“The findings support the view that head direction cells are necessary for the periodic firing structure of grid cells,” added Moser.

T memory stem cells

WIKIMEDIA, NIHModified lymphocytes transplanted into patients more than a decade ago have been identified as T memory stem cells in a study published in Science Translational Medicine this week (February 4). A team led by investigators at the San Raffaele Telethon Institute for Gene Therapy in Milan showed that these T memory stem cells were not only long-lived and hardy, but flexible—they could differentiate into several T cell types.

“For the first time there is monitoring of the clonal dynamics of T memory stem cells in humans for a long period of time—up to 12 years,” said transplantation and immunology expert Luca Gattinoni at the National Cancer Institute who was not involved in the work. “It provides the best evidence so far of the ability of stem cells to survive . . . and to sustain an adult T-cell population.”

Nitrogen fixer

UNIVERSITY OF INDIANA, BREAH LASARREThe bacterium Zymomonas mobilis can convert atmospheric nitrogen gas into ammonium, researchers at the University of Indiana have found. Their results were published in PNAS this week (February 2).

“It was known already that the Zymomonas genome contains all the genes that are needed, but nobody had checked whether they really are able to fix nitrogen,” said Uldis Kalnenieks of the University of Latvia who was not involved in the research.

“The genes might have been there and annotated in the past, but this [study] now enables perhaps the industrial side to develop it,” said Steve Brown of Oak Ridge National Laboratory in Tennessee who also was not involved in the work. “This opens the door to further studies in this system so I think that’s a pretty exciting result.”

Other news in life science:

Obama’s Budget Seeks Science Boost
Fiscal year 2016 could be very bright for the research enterprise if the President’s budgetary requests are granted.

UK Supports Three-Parent IVF
Parliament today voted to allow techniques that could help couples produce babies with a reduced chance of passing on heritable mitochondrial diseases.

Taking Turns
Using GPS trackers, researchers demonstrate an energy-saving flight strategy for migratory birds.

Smartphone Diagnostic
Researchers design a device that attaches to a smartphone to test for diverse infectious diseases from a drop of blood.

Inferior Sperm
A study in an African bird species sheds light on age-related gamete decline.