At the very first stages of specialization of germ cells choose their fate, turning on and off the different genes.

Human embryo at the eight cell stage – within two or three days after fertilization. (Photo: tomasreyesvarela /

Although we say that embryonic cells have no worries except the time share, and any specializations they are not, they still differ from each other. And the differences between them appear at the earliest stages of embryonic development.

In the future, different types of stem cells of the embryo will give rise to tissues and organs: epithelium, blood, brain, countless neurons, etc. – all this happens on the cellular standards more soon, and the path of specialization will be very long, but it starts, again, very, very early . Before implantation of the embryo in the uterine wall, its cells have time to divide into two classes, and then the embryo is growing Yes differentialsa: different parts of it acquire the characteristics, functions, etc.

It is clear that when the cell wants to be different from its neighbors, it changes the activity of genes. Different functions need different genes, so that cells performing the same role will be similar and the genetic activity: they will work about the same genes, and other genes, on the contrary, cells shut off.

Mohammed Hisham (Hisham Mohammed) and his colleagues Abrahamtora Institute in Cambridge discovered that when embryonic stem cells decide who to be, it does not mean that they are together off have the same genes and include others. On the contrary, before the next stage of differentiation of the cells turn on and off what they can, choosing from genetic noise, what need and what no need. And there is no match in the genetic activity between the cells there; choosing their own destiny, they are “noisy” inconsistent, turning on and off gene individually, not looking at neighbors.

Managed to figure it out using the methods of individual sequencing RNA: as you know, the activity of genes can be estimated by the number of molecules-mediators of RNA that are synthesized on DNA, and now we can analyze the composition of RNA in a single cell. And here is the diversity of RNA demonstrated that the apparent confusion that reigns in the molecular kitchen of embryonic cells before the next step in its specialization.

Pavlychev and polyglycol their genes, the cell eventually realizes that she needs later in life, and subsequently, when the choice is made, cells of the same fate in genetic terms are already the same. However, as emphasized by the authors in their article in Cell Reportsthat cell went on a particular journey, at the beginning it needed just such a noise. (Here it should be clarified that the researchers were engaged in the very first events of cellular differentiation, and possibly at later stages of embryonic development, all without “guessing in the genes”.)

Of course, genetic noise should have their molecular regulators that trigger all this violent molecular activity, but more details here will become clear only after the following experiments.