Scientists from Japan found a way to ease the layout of the neurons of the nematode Caenorhabditis elegans. For this, the researchers created a new line of worms, the nervous cells which Express a set of markers, and an algorithm that allows the identification of neurons semi-automatically. With the help of this approach accurately able to determine not all of the neurons to improve the method we need to expand the sample and look for additional markers. Article published in the journal BMC Biology.
The nematode Caenorhabditis elegans, all 302 neurons. The morphology of these cells, their paths of differentiation and communication are well studied. Therefore, C. elegans is a unique model where it is possible to study processes at the level of individual cells and entire neural networks. Modern methods allow to visualize activity of the entire nervous system of this round worm, including if it is freely moving, with a resolution of one neuron. But, unfortunately, to determine for which of the 302 nerve cells we observed, it is necessary manually.
In order to identify individual neurons that use primarily the location of the cells. But always it is only on the larval stages and in adult worms was variable. In addition to the positions of the cells are also determined by specific markers (e.g., fluorescent labels) and morphology. However, all these methods are convenient only if you consider the limited number of neurons. At the level of the whole brain to determine each individual cell is difficult: you need too many markers and morphological characteristics is not always possible to consider.
Researchers have made several attempts to automate the determination of neurons in C. elegans. Fugui LUN (Fuhui Long) have created electronic 3D-Atlas of nematode larvae L1, in which the marked position 357 of 558 cells in the worm, and their variants. However, the work is not described neurons of the head end of the nematode due to the fact that they are too tight. In another Atlas with fluorescent labels, the position and morphology of the cells marked 154 of 959 cells of the adult individuals, but there generally has not entered neurons. Still to obtain information about the position of Mature neurons in C. elegans was only possible from the reconstruction by John white (John White) in 1986, but this work is not specified the arrangements of the cells and there are some inaccuracies associated with the methodology for the preparation of samples for electron microscopy.
Teshima Yu (Yu Toyoshima) from the University of Tokyo and his colleagues have created a new set of identifiers for neurons of C. elegans. To do this they have marked specific for different cells, the promoters of fluorescent label. Promotor — DNA segment that serves as a start for transcription. In different cells work their promoters and can be done so that the expression of a specific promoter will be allocated to the fluorescent protein. The change of a luminescence label, which displays the pattern of work of the promoter, and the researchers used to identify neurons.
The researchers observed the expression of 35 different promoters in the nerve cells 311 nematodes. The researchers then compared the location of the same cells for different species and determined which cells can move a lot relative to each other and which pairs are relatively constant in space.