Complex organisms (such as mice, fish, flies or worms) are formed by millions of cells. But those cells are not all the same, they have divided into groups or families of cells and each group is specialised in doing a certain function in the organism. Therefore, we have similar cells that work together to produce the arteries that distribute the blood throughout the organism and those cells are very different from the ones that form the bones that give shape to the organism.
Hence, organisms are formed by lots of different cells which perform diverse functions and are located in different places in the organism. But all of this diversity originates from a single fertilised egg cell, formed by the fusion of two cells from each progenitor, which contains a single genome. So, how is it possible that with only one set of information (a single genome) the single fertilised egg cell develops so many different cells to create a complex organism? This is one of the main questions of Biology and there is a whole discipline dedicated to answer it: Developmental Biology.
The aim of my research is to get a better understanding of the differentiation of a single cell into several specialised cells and understand how the new cells created from the single cell embryo choose their fate, i.e. how a cell chooses to become a bone cell or a brain cell.
To understand this developmental process of fate choice and cell specification we use zebrafish as a model organism where we perform our experiments. These little fish are very useful in research because they are cheap to grow and easy to maintain, their embryos are transparent and the adult fish produce lots of embryos when they mate. They are a great tool to understand developmental biology processes. From all the different kinds of cells that form a zebrafish my research is focused on understanding melanocytes development in the early stages of embryo development, after the egg cell has been fertilised by the sperm; i.e. how after the single cell embryo has divided itself and it has created several cells, some of them choose to become melanocytes and what changes they experience to become a fully differentiated melanocyte or an “adult” melanocyte, if you like.
The image shows the early developmental stages of a zebrafish embryo. On the left we can see the single cell embryo just after fertilisation and on the right we can see the embryo 24 hours after the fertilisation. As you can see, in just 24 hours there have been huge changes and you can start to identify a fish shape in the embryo. Image adapted from Kimmel et al. 1995.
Melanocytes are pigment cells that have a brownish colour and give the colour to our skin. These cells are a great model to understand development because they are big and black, which makes them easy to see and follow in the transparent fish embryos as they develop. Also, melanocytes are the cells that cause melanoma when something wrong happens in its genes. Melanoma is one of the most aggressive types of cancer and it has difficult treatment. Therefore, understanding how melanocytes are created and how they work is very important to figure out how development happens and also to understand what makes a melanocyte lose its control and become a cancer cell.
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