Genes & Cells

New ways to kill harmful bacteria, plus test-tube sperm and insulin alternatives in this week’s news

Test-tube sperm
Researchers in Japan have devised a method for making sperm from mouse testicular tissue grown in the laboratory. The lab-made sperm could fertilize eggs that would later grow into mouse pups, the team reports in the March 24 Nature. The testicular tissue could also be frozen and thawed later to make sperm. The technique may one day help diagnose and treat human male infertility. Previously, other researchers had reported growing sperm from embryonic stem cells, but this new procedure does not require the creation of stem cells. —Tina Hesman Saey

Melanoma mechanisms revealed
Some striped fish may have led scientists to new therapies for treating a deadly skin cancer. Using zebrafish, Leonard Zon of Children’s Hospital Boston and colleagues have discovered two new genes involved in melanoma growth. In the first of two studies appearing in the March 24 Nature, Zon’s team found that higher-than-normal levels of a protein called SETDB1 can worsen melanoma. In the second paper, the researchers report that an arthritis drug called leflunomide may help fight melanoma by inhibiting an enzyme known as DHOH. Together with an experimental chemotherapy drug, leflunomide was able to slow or reverse melanoma tumor growth in mice. —Tina Hesman Saey


Bacteria, kill thyself
Bacteria may commit suicide by taking a poison of their own devising. E. coli and some other species of bacteria make a suicide toxin called PezT, which is usually inactivated by an antitoxin called PezA. No one knew how PezT killed bacteria because it works so quickly. Now, researchers in Germany have found that the toxin converts a normal cell wall component into a form that weakens the wall. Then, internal pressure causes the bacteria to explode like an overstuffed man eating a thin mint, the researchers report online March 22 in PLoS Biology. Such toxins could be made into new types of antibiotics. Tina Hesman Saey

Possible insulin alternative
A protein made in the small intestine after a meal may help alleviate some complications of type 2 diabetes. In type 2 diabetes, the liver and other organs become insensitive to insulin, leading to conditions such as high cholesterol as well as high blood sugar. Now, researchers at the University of Texas Southwestern Medical Center at Dallas and colleagues report in the March 25 Science that FGF19, a growth factor protein, can perform some of insulin’s functions in the liver. The protein restored the liver’s ability to make glycogen, an important energy-storage molecule, in diabetic mice, but without causing the liver to make more lipids as increased insulin activity can. —Tina Hesman Saey

Preeclampsia genes discovered
Genetic variants in two genes that are part of an infection-fighting system in the human body may cause a serious complication of pregnancy. About 5 percent of pregnant women develop a condition called preeclampsia, a defect in the placenta that leads to health complications for the mother and premature delivery. Women with autoimmune disorders called lupus and antiphospholipid syndrome have a higher risk of preeclampsia. An international team of researchers report online March 22 in PLoS Medicine that mutations in genes called MCP and CFI were linked to preeclampsia in 18 percent of women who had the immune disorders and in 10 percent of otherwise healthy women. —Tina Hesman Saey