Researchers have created an interactive animation that shows the development of each embryo cells of the ascidians Phallusia mammillata until stage 64 cells. Gene expression, morphology and origin of each cell was reconstructed using the method of sequencing RNA in single cells, which was a breakthrough in 2018, according to the magazine Science. Model available online, and a study published in the journal Cell.
Multicellular organisms develop from a single cell — the zygote. Knowledge about how enabling the expression of different genes holds each of the cells of the embryo on its journey of differentiation, fragmented. RNA sequencing of single cells allows to know which genes are active in a separate cage, and share the body at the cellular population. However, we often don’t know where it came from studying the cell and what is its fate.
Scientists from Germany and Italy under the leadership of Pierre Neveu (Neveu Pierre) from the European molecular biology laboratory conducted a RNA sequencing of single cells of embryos of the ascidians Phallusia mammillata. The embryos of these vertebrates are transparent, and the fate of their cells is determined at the stage of 64 cells. Results sequencing combined with a 4D reconstruction of the embryo (the fourth dimension being time), which he received by means of planar illumination microscopy.
Researchers have dissociirovati embryos of all stages from two to 64 cells and isolated individual cells: total RNA sequenced more than one thousand cells from 58 embryos.
At various stages it was possible to allocate group of cells, which expressed a close set of genes. For example, in the first stage, the expression profile of both cells were identical, and at the stage of four cells in all embryos, it was possible to distinguish two pairs of symmetric cells. In the last phase studied (64 cells), the scientists found 18 separate cell types, symmetrical relative to the axis of the embryo. At this stage the pattern of expression of each cell determines what kind of tissue it will give rise.