Genetic map of the brain
American scientists from the Allen Institute for Brain Science in Seattle are going to create a three-dimensional map of the human brain, which shows the activity of 20 thousand genes. The cost of the project, designed for four years, is $ 55 million.
The brain is the command organ of the human body, and its complex work is provided by a huge number of genes responsible for the synthesis of various protein molecules.
If you understand in which structure of the brain, which genes are in working order, then you can learn a lot about the activity of proteins and the functions of different parts of the brain.
"Decoding the human genome answered the question "what?", and our project will answer the question "in what place?" – explains Alan Jones, a leading researcher at the Institute (Brain map project set to revolutionize neuroscience – Peter Aldhous, NewScientist, March 13, 2008).
In 2003, neurophysiologists from the Allen Institute have already presented to the world a three-dimensional genetic atlas of the mouse brain. It was created by the so-called "in situ hybridization" method. Recall that RNA is a molecular cast of a gene – a single polymer DNA chain. If a gene in a cell "works", then the cell synthesizes RNA molecules corresponding to the structure of this gene. By what kind of RNA is formed in a given cell, we can conclude which genes are active in it.
For example, you need to determine whether a known gene is active or not. First, scientists synthesize a sequence of nucleotides complementary to the RNA of this gene, then "sew" a fluorescent "label" to the synthetic RNA molecule. Ultrathin slices of the brain are placed in a solution of "labeled" RNA. If there is a complementary synthetic RNA in the studied part of the brain, then, having met, both molecules "recognize" each other and connect, forming a strong complex. A part of the brain is "glowing" – the desired gene is active, not "glowing– - not active. So all the genes of the mouse genome were scanned. The atlas created on the basis of this information makes it possible to identify functionally active areas of the mouse brain responsible for certain animal behavior.
There are not many more genes in the human brain than in the mouse, but the human brain itself is 2000 times larger than the mouse brain. Therefore, scanning the activity of genes in all its areas is an incredibly ambitious task. Scientists are going to solve it this way. They will divide the brain into several hundred anatomical parts, isolate a mixture of RNA molecules from each part and analyze its composition using a "gene chip". The chip consists of cells in which probe molecules are placed. The cells in which the RNA probe and the RNA molecule from the natural extract "recognized" each other fluoresce. Thus, scientists will receive information about the composition of RNA and the activity of genes in different parts of the human brain. When the results of this first stage, which is designed for two years, are received, scientists are going to carry out "in situ hybridization" for the brain as a whole only for active genes, which will significantly reduce the amount of work.
Researchers hope that a three-dimensional genetic map of the human brain will lead to a significant development of neurophysiology. In their opinion, the genetic map of the brain will reveal which genes are disrupted when malignant tumors occur, and understand the nature of many neuropsychic diseases. A comparison of the genetic map of the mouse and human brains will show how the evolution of cognitive activity took place and what are the fundamental differences between the work of the mouse and human brains.
Portal "Eternal youth" www.vechnayamolodost.ru based on the materials of "Science and Life"
11.04.2008