In a new study, Yale researchers demonstrate Zika virus infection of cells derived from human placentas. The research provides insight into how Zika virus may be transmitted from expectant mother to fetus, resulting in infection of the fetal brain.

Protective telomeres are augmented by freely diffusing telomerase. As the rope of a chromosomes replicates, it frays at the ends. No problem: A chromosome's ends have extra twine so that fraying doesn't reach into the body of the rope where the important information resides. This extra twine is called a "telomere". Over time and across replications, this telomere twine breaks down until the chromosome loses its protective ends and this "fraying" reaches into the rope, wrecking the chromosome and resulting in the death of the cell.

Researchers at Washington University School of Medicine in St. Louis have identified the protein that norovirus -- shown here in a colored transmission electron micrograph -- uses to invade cells. Norovirus is the most common viral cause of diarrhea worldwide, but scientists still know little about how it infects people and causes disease. Research has been hindered by an inability to grow the virus in the lab.