our health 33

The production of neurons and glia in the developing cortex is tightly regulated. RGPs produce the majority of them. In previous studies, Hippenmeyer and colleagues have shown that the division pattern of RGPs is not random. They have demonstrated that each individual RGP produces a predefined unit of neurons and glia cells in a precisely orchestrated developmental program which ensures that the brain faithfully grows to its normal size. In the present  Neuron  study, the authors asked what mechanisms control the exact output of RGPs. In particular, the researchers investigated the role of the gene Lgl1, which had been predicted to regulate RGP proliferation. The gene's precise role was previously unknown and Hippenmeyer and colleagues now used a technique called MADM, short for Mosaic Analysis with Double Markers in order to decipher the function of Lgl1 in RGPs at unprecedented single cell resolution. Using MADM, Hippenmeyer and colleagues eliminated Lgl1 either in ju...

The mechanisms that activate these special stem cells or make them go back to sleep after their work is done have remained elusive until now. The scientists have now identified retinoic acid, a vitamin A metabolite, as a crucial factor in this process. If this substance is absent, active stem cells are unable to return to a dormant state and mature into specialized blood cells instead. This means that they are lost as a reservoir. This was shown in studies with specially bred mice whose dormant stem cells are green fluorescent. "If we feed these mice on a vitamin A deficient diet for some time, this leads to a loss of the stem cells," said Nina Cabezas-Wallscheid, who is the first author of the publication. "Thus, we can prove for the first time that vitamin A has a direct impact on blood stem cells." This finding not only enhances our understanding of the development of blood cells, it also sheds new light on prior studies that demonstrate that vitamin A defi...