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--- chapter_16 [2025/05/15 13:31] – mike
+++ chapter_16 [2025/05/16 21:53] (current) – [Creating knockout mice] mike
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-This gave scientists an opportunity to genetically manipulate ES cells in a Petri dish, in an analogous way as we might genetically manipulate yeast or //E. coli// cells in a Petri dish. Importantly, this further gives scientists the opportunity to isolate clones as colonies and also the ability to grow a large number of cells to screen for rare events such as homologous recombination (it is far easier and cheaper to grow thousands of cells in a dish than it is to grow thousands of mice in cages). Once you have identified mouse ES cells (originally from a gray furred mouse) that have been genetically altered the way you wish, these cells can be used to generate a living animal that is fully derived from these totipotent ES cells.
+This gave scientists an opportunity to genetically manipulate ES cells in a Petri dish, in an analogous way as we might genetically manipulate yeast or //E. coli// cells in a Petri dish. Importantly, this further gives scientists the opportunity to isolate clones as colonies and also the ability to grow a large number of cells to screen for rare events such as homologous recombination (it is far easier and cheaper to grow thousands of cells in a dish than it is to grow thousands of mice in cages). Once you have identified mouse ES cells (originally from a gray-furred mouse) that have been genetically altered the way you wish, these cells can be used to generate a living animal that is fully derived from these totipotent ES cells.
 ===== Selecting for homologous recombination in ES cells =====
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 ===== Creating knockout mice =====
-The next step is to create a mouse in which every cell in the mouse contains the genetic alteration you just created in ES cells. The first thing to note is that the ES cells in which we knocked out gene X are from a mouse strain that has gray fur. We will inject these ES cells into a new blastocyst embryo that comes from a mouse strain that has white fur (Fig. {{ref>Fig4}}). Usually, we will do this for a few dozen embryos, which are then implanted into foster mothers. Some pups born from these foster mothers will have both white and gray fur - they are chimeras. We then take male chimeric pups and breed them to white females. Since the gray fur phenotype is dominant, any chimeric father that has germ cells that formed from our modified ES cells will produce pups will all gray fur; these pups are then founders for a knockout mouse line (Fig. {{ref>Fig5}}).
+The next step is to create a mouse in which every cell in the mouse contains the genetic alteration you just created in ES cells. The first thing to note is that the ES cells in which we knocked out gene X are from a mouse strain that has gray fur. We will inject these ES cells into a new blastocyst embryo that comes from a mouse strain that has white fur (Fig. {{ref>Fig4}}). Usually, we will do this for a few dozen embryos, which are then implanted into foster mothers. Some pups born from these foster mothers will have both white and gray fur - they are chimeras. We then take male chimeric pups and breed them to white females. Since the gray fur phenotype is dominant, any chimeric father that has germ cells that formed from our modified ES cells will produce pups with all gray fur; these pups are then founders for a knockout mouse line (Fig. {{ref>Fig5}}).
 <figure Fig5>