As stem cells can divide asymmetrically, segregation of harmful factors to the differentiating daughter cell
could be one possible mechanism for slowing damage accumulation in the stem cell.
When a stem cell in the fruit fly gut divides, it creates a daughter cell
that wraps itself around its mother and siblings and prevents them from turning into specialized tissues, researchers report online January 7 in Science.
During each cell division, the theory went, only the newly replicated strands of DNA were passed to the daughter cell
, while the mother strand was maintained by the original stem cell.
Habib and his colleagues also found that the daughter cell
closest to the Wnt3a signal expressed proteins showing it was maintaining its pluripotency, or ability to function as a stem cell like its parent.
Each of these cells divides into two cells: One that replaces itself and another that differentiates into a pigment-producing daughter cell
called a melanocyte, which imbues hair with its browns, reds and blacks.
The researchers showed that a gene named SAPCD2 influences cell division orientation and controls daughter cell
fates in vivo.
An adult stem cell spawns a daughter cell
that then develops into one of the various cell types within a particular organ.
Two types of stem cells exist in the fruit fly testis: One whose fate is to produce a daughter cell
that matures into a full-fledged sperm cell and a daughter that stays as a stem cell (otherwise, in each division the tissue would lose a stem cell and quickly exhaust its capacity for renewal), and a second stem cell type that is a somatic, or non-sex, stem cell that similarly produces a daughter that stays as a stem cell, and another daughter that matures into a protective cell that flanks the maturing sperm cell in an encysting process.
The biological process of mitosis is tightly regulated by specific biochemical checkpoints to ensure that each daughter cell
receives an equal set of sub-cellular materials, such as chromosomes or organelles, to create new cells properly.
As a stem cell divides, one daughter cell
moves out of the niche to generate mature sperm cells.
When a stem cell divides into two, one daughter cell
remains as an undifferentiated stem cell, thereby preserving that cell's potential for regeneration and repair.