GPS for chromosomes: Reorganization of the genome during development

The spatial association of genetic materials inside the cell nucleus performs an essential position within the improvement of an organism. A analysis group from the College of Basel, in collaboration with scientists from Harvard College, has developed a technique to hint the chromosomes in particular person cells. Utilizing this technique, they’ve now been capable of reveal that chromosomes reorganize throughout embryonic improvement. The research has lately been revealed in Molecular Cell.

Our physique is made up of all kinds of cells with essentially the most numerous features. Regardless of being coronary heart, liver or nerve cells, nonetheless, all of them comprise the identical genetic info. The rationale why cells develop in another way is that solely components of their chromosomes are learn. This ends in some genes being lively whereas others, in distinction, are silent.

For gene activation, each the way in which the genes are packaged in addition to their spatial group within the cell nucleus play a decisive position. Prof. Susan Mango’s group on the Biozentrum of the College of Basel has now investigated this 3D structure extra carefully. Utilizing a novel method, they had been capable of hint particular person chromosomes throughout embryonic improvement in nematodes and present that they rearrange themselves through the early part.

Chromosome association isn’t random

If stretched out, all of the DNA molecules of a cell would attain about two meters in size. So the DNA should be densely packed to suit right into a cell nucleus of solely few micrometers in dimension. The DNA strands are very tightly coiled and twisted to type space-saving constructions, known as chromosomes. The packaging and the association of the DNA of the chromosomes determines the exercise of genes.

Of their research, the researchers led by Prof. Susan Mango traced particular person chromosomes and investigated their group throughout early embryonic improvement. Embryonic cells of the nematode C. elegans served as a mannequin. “Utilizing a novel method, we had been capable of observe the spatial rearrangement of chromosomes in single cells firstly of embryogenesis,” says Mango. “The benefit of this technique is that the cells and tissue stay fully intact.”

Early chromosomes resemble a barbell

It’s nicely know that chromosome areas with related useful properties contact one another and work together. Which means that chromosome domains segregated into two compartments, lively and inactive. “Throughout early embryogenesis, nonetheless, the chromosomes are organized in another way,” says Ahilya Sawh, first writer of the research. “Within the early embryo, they’re organized into an unconventional barbell-like construction, with inactive compartments separated by a central lively area.” The researchers found that the nuclear lamina — a protein mesh lining the interior floor of the cell nucleus — is required to realize this barbell association. The lamina is connected to the inactive sections and stretches the chromosome.

Chromosomes reorganize throughout embryogenesis

“Solely at a later stage of embryonic improvement, when the germ layers develop, we really see the well-known segregation into an lively and inactive area,” explains Mango. “Utilizing chromosome tracing, we had been capable of map the entire 3D chromosome structure and will present for the primary time that chromosomes rearrange throughout early improvement, a maturation course of that requires the nuclear lamina.”

The reorganization of the chromosomes accompanies cell maturation and represents a milestone within the improvement of a posh organism. The right chromosomal structure is essential to forestall developmental problems.


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