Hannele Ruohola-Baker, PhD (Biochemistry)
This group has recently shown that Dcr-1-deficient germ line stem cells are delayed in the CDK-inhibitor We p21/p27/Dacapo-dependent G1/S transition, suggesting that miRNAs are required for stem cells to bypass the normal G1/S checkpoint (Hatfield et al., 2005, Nature). Hence, the miRNA pathway might be part of a mechanism that makes stem cells insensitive to environmental signals that normally stop the cell cycle at the G1/S transition. Since miRNAs are a novel class of genes involved in human tumorgenesis, it is tempting to speculate that miRNAs could play a similar role in cancer cells. The investigator is now moving towards analyzing micro RNA function in humans.
Billie Swalla, PhD (Biology)
We are studying stem cells in colonial ascidians. In botryllid ascidians, there are multiple stem cells which circulate in the blood. Some stem cells are necessary to form a new individual asexually, and there are also germline stem cells for gametes to develop in the ovary and testes. We are developing molecular markers to identify various stem cells circulating in the colonial ascidians, in order to understand their potential. Brown et al. (2009; Development 136: 3485-3494) has shown that there are germline precursors that are specified early, but then continue to populate gonads as they develop. We have also shown that these colonial ascidians undergo extensive regeneration, thorough activation of a piwi-positive stem cell population (Brown et al. 2009; JEZ:MDE 312B: 885-900).