A Mouse With Two Dads — and a New Frontier for Biology | Katsuhiko Hayashi | TED

0:04 it is my great pleasure to be here to share some news from biology today with you so your life and mine start with this the union of spam and egg the fertilization involves spam from the father and egg from the mother they meet in usual way and parze the Egg acquire the potential to give rise to the individuals like you and me if you trust back your generation you are derived from your parents and your parents are derived from your grandparents and so on in distant past this perpetuity can only be achieved through what biologist like me called Jam cell lineage these are the only cells that are immotile among more than

0:51 200 type of cell in your body the Let Die is you so these Immortal jum are called garet are very important and we call them Jam line in our society this unbroken line is under threat the present Generations are having a children later and later and the older Jam cells are less likely to result in successful fertilization which leads to the declining BS rate it's not just a people continuous decrease in the reproductive rate of large livestock had resulted in huge economical losses setting aside human needs there are endangered animal down to few individuals how can we preserve them

1:38 that is where the assisted reproductive technology offered hope since robertto Edwards successfully combined human Jam in the dish more than 12 million baby have been born through this technology called the invital fertilization however current assisted reprodu technology can only be applied if spam and egg can be obtained from the body if not there are no option available but I would ask now can we create a jam the dish so this is a question so let's start with how the J cell formed in the body after fertilization fertilize the egg under go C divisions and differentiate into the

2:25 different cell types as it further developed original cell of eventual spam and egg known as a primodial gam cell emerge then these primodial G cell then differentiate into the primary egg known as oide in the female or spermatogonia the spray C of spam in the male these Ang sperm mature over time which is associated with the sexual maturation of individuals now imagine if this entire process were to occur outside the body so my team and I have been focusing on replicating this entire process in the dish known as a invital g Genesis the key to generating the jam in the dish is

3:12 a type of cells called Pur potent stem cells because they each have a ability to differentiate into the any cell type in the body Maring EV show that such a purely potent stem cell could be derived from pre implantation embrya in mice and jam somson showed it could done in human based on these breakthroughs sh yamanaka Show that any kind of cell in the body could be turned into the P potent stem cells simply by expressing a specific set of proteins these are called induced P poent stem cells and they possess a same potential as those dered from the embryos by using these P poent stem cells we can hijack the jam line during normal development cell receive a signal that guide their differentiation into

3:59 the different type by mimicking right signals fuel potent stem cell can be directed along the pathway to differentiate into the eggon sparm this has been successfully demonstrated in our laboratory by using Mouse P Buton stem cells by providing appropriate signals we were able to generate mature egg from m p poent stem cells also to achieve this we created a mini ovary from P poent stem cells allowing the o side to mature outside the body importantly egg produced in Dish are capable of the fertilization and giving rise to yet more mice like this these look same as any other mice they grow up

4:46 they eat the food they breed and Li but in this case genetic Mar of this mice is the P poent stem are growing the dish with this inam Genesis the process of creating egg require only skin cells or other easily collectable cells from the body even cells and urine so this means actually this kind of Technology can be applied to the various M species including humans livestock or even endangered animals several research group have successfully uh produced the prim gam from P poent stem in all these cases notably our laboratory is actively involved in depopulation effort for the northern wide life NOS suddenly there are only two female

5:33 who remain on this planet we have generated the uh egg prors from the northern white line in this P poent stem cells and then currently creating a mini ovary system to mature these prasa into the eggs but we can go further than it by using this technology we can skip the sex dependent reproduction today jams have different shape and different fun function based on the sex this difference is genetically made by the sex chromosome in the human male have a X and Y chromosome and the female have two X chromosomes from genetic Viewpoint this is only difference between male and female but in add dis we can eliminate

6:19 this difference so our laboratory succeeded in the switching from the XY chromosome the XX chromosome how did we do that well we took this cell from the male mice and then made induced P poent stem cell which have X and Y chromosome of course then we made a lot of these cells in some R population unal segregation of sex chromosome occur during T division which means some XY chromosome Become One X chromosome that then double and become two X chromosomes we picked up a very rare population these cells that have about 2 X chromosome and we made the egg the egg derived from sex converted induced P poent stem cells behave exactly egg from

7:07 traditional females we then fertilize sex converted egg with the spam and this give rise to typical healthy mice like this they grow up they eat the food uh they made and live wrong just like a conventional bre mice the only difference is these are derived from to that looking at the history of reproductive technology like this technology is developed in the the experiment experimental animal like this can eventually be applied to the human and other animals today the production of egg in the dish even from traditional male cells open a new possibility for the reproduction in the

7:54 future we can create a jam in the dish and they can come from two fathers two mothers or perhaps other combinations thank you