The crucial hours that shape you
Inspired byCarmina Perez Romero (doctorante à la McMaster University/UPMC) Tuteurs : Cécile Fradin (professeur à la McMaster University) and Nathalie Dostatni (professeur à l'Institut Curie – PSL et UPMC).
Have you ever wondered how a single cell can become a full grown organism? Well it starts when an egg and sperm fuse together making a single cell as time passes it start dividing over and over again, until they form an organism. During this developmental process, somehow the cells know exactly where they are and what they need to become, so that they form the organism. However, we don’t fully understand this process and this is what our research hopes to answer: how the cells know where they are? What they need to become?
We study this process in fruit fly, although fruit flies might not look a lot like us, during early embryonic development we are quite similar, so we can try to answer this questions in fruit flies and what we find might be relevant to other organism like us.
During development the first thing that an embryo needs to know is the orientation of the body, where the top and bottom, the left and right and the back and front of the body will be. We concentrate on studying how does the “head to tail” axis, which we call the anterior-posterior axis, form.
To know where the head is going to be, the embryo releases proteins called morphogens that broadcasting instruction to other genes so that the cells know where they are and what they should become. This morphogen is called Bicoid, its concentration is much higher at the head of the embryo and lower as you move towards the tail, you can see this on the Movie 1 where Bicoid is labeled in green using a green fluorescent protein. Bicoid activates Hunchback, which end up diving the embryo in two parts the top and bottom. However Bicoid’s is message fades away after each cell division, so we don’t know how is the message relayed over time?
Well we believe cells have memory, they know who their mother was and remember the instruction so that they know where they are and what they will become. To study this hypothesis, our laboratory has worked in trying to see Hunchback expression in real life, so that we can get information about how it is activated and to follow it over time. In Movie 2 you can see in green is Hunchback RNA being activated, and in red the DNA histones and we can follow this over time. With these movies we can start to study if a mother was activated and a daughter is activated, and finally see if cells have memory.