Unraveling Stem Cells’ Secrets: Immortality of Germline Cells and the Function of “Junk DNA”
upstart writes:
When cells divide, they usually generate two identical daughter cells. However, there are some important exceptions to this rule: When stem cells divide, they often produce one differentiated cell along with another stem cell, to maintain the pool of stem cells.
Yukiko Yamashita has spent much of her career exploring how these asymmetrical" cell divisions occur. These processes are critically important not only for cells to develop into different types of tissue, but also for germline cells such as eggs and sperm to maintain their viability from generation to generation.
She spent her Ph.D. studying how cells make exact copies of themselves, but as a postdoc she turned her attention to exceptions to that process, which is very important because that is how one original cell can turn into so many different kinds of tissues. She focused on so-called junk DNA. These sequences make up most of the genome, but were thought to be useless because they don't code for proteins. However, her work showed that stretches of junk DNA act like barcodes that label each chromosome to keep them bound together. Without the codes, the chromosomes scatter and leak out of the cell nucleus. Her lab also showed that these barcodes are unique to each species, and that the junk DNA of one species cannot necessarily code the chromosomes of another.
[...] We think that might be one of the big reasons why different species become incompatible, because they don't have the right information to bundle all of their chromosomes together into one place," Yamashita says.
Read more of this story at SoylentNews.