Many researchers have suggested for some time that the Zika virus may have serious health consequences—particularly on brain function. Several months ago, health officials verified that the virus can cause a range of congenital birth defects, including microcephaly and brain damage in infants born to mothers who were infected during pregnancy. Zika's effects on adults have not yet been studied widely. Although most adults who contract the virus remain asymptomatic, some researchers suspect the Zika virus may also have deleterious effects on the adult central nervous system in ways that we don't fully understand. Simply put, Zika may not be as innocuous for adults as public health officials currently claim. A new study published Thursday in Cell Stem Cell contains some of the first research to look specifically at how the virus may affect the brains of adults who become infected.
Stem cells create new nerve cells in the brain over the entire life span. One of the places this happens is the hippocampus, a region of the brain that plays a significant role in many learning processes. A reduction in the number of newly formed nerve cells has been observed, for example, in the context of depression and Alzheimer's disease, and is associated with reduced memory performance in these conditions. In a study published in Nature Neuroscience , the group around Sebastian Jessberger, a professor at the University of Zurich's Brain Research Institute, has shown that stem cells in the hippocampus of mice are active over a period of several months. The researchers, led by PhD candidate Sara Bottes and postdocs Baptiste Jaeger and Gregor Pilz, employed state-of-the-art microscopy and genetic analyses using single-cell RNA sequencing of stem cells and their daughter cells to analyze the formation of new nerve cells. This enabled them to observe that specific stem cell populations are active over months and can divide repeatedly. This had already been suspected in earlier studies, but this is the first time there has been direct evidence.
Some tissues in the adult body, such as the epidermis of the skin, the lining of the small intestine , and bone marrow , undergo continuous cellular turnover. The stem cells exist in niches formed by other cells, which secrete substances that keep the stem cells alive and active. Some types of tissue, such as liver tissue, show minimal cell division or undergo cell division only when injured. In such tissues there is probably no special stem-cell population, and any cell can participate in tissue regeneration when required. The epidermis of the skin contains layers of cells called keratinocytes.
Sleep is an important part of your daily routine—you spend about one-third of your time doing it. Quality sleep — and getting enough of it at the right times -- is as essential to survival as food and water. Sleep is important to a number of brain functions, including how nerve cells neurons communicate with each other.