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It has been A A long-standing enigma in biology: How can cells know how big they are?
The answer seems to have been hidden in Robert Sablowski’s computer files, and has been collecting virtual dust since 2013. “I’ve had data for years and years, but I wasn’t looking for it in the right way,” says plant cell biologist Sablowski. At the John Innes Center in Norwich, England. For a previous project he was researching a protein called KRP4. To shine by fusing jellyfish with a fluorescent protein, Sablowski could study it inside a plant cell, but he had no idea that it would be the key to understanding the regulation of cell size.
In order for organisms to develop, their cells must undergo a pattern of growth, DNA replication, and division. But scientists studying this process, known as the cell cycle, have long noticed that divisions do not have to be the same – cells often divide asymmetrically, and their size is corrected later. In one research published in Science last month, Sablowski and his colleagues revealed how plants are doing: cells use them as a glass to measure their DNA. While the discovery was made by examining a plant Arabidopsia, may have broad implications for understanding the regulation of animal and human cell size, and may also have an impact on the future of crop production.
Identifying how cells evaluate their size has been complicated because most cellular proteins scale up to the size of the cell itself. Sablowski compares yourself to trying to measure yourself with your arm. “You can’t do that because your arm grows in proportion to your body,” he says. “You need an outside reference to find out how big you are.” What does not change as the cell grows, however, is its DNA. Scientists have long thought that a cell could use its DNA as an indicator of some kind of size, but Sablowski’s team is the first to show evidence of this process.
“It has been a deep mystery in biology for many decades to figure out how cells can magically perform their task almost magically,” says Martin Howard of the John Innes Center, who helped develop the mathematical models needed. progress. Regulating shape and size is important because they are closely related to the functioning of cells: it is too large and it can be difficult for cells to quickly retrieve information contained in their DNA; it is too small and the cell does not have enough space to divide, creating defects that can cause disease and growth.
Arabidopsia According to Sablowski, grass is a herb, but it is considered a model organism in plant biology because it is easy to grow and matures quickly. This means that other researchers in this field have studied it well. “Community Arabidopsia it has been critical, “says Marco D’Ario, a graduate student at the John Innes Center, who designed and helped design the experiment.
The group grew Arabidopsia about six weeks in pots, the tiny tip of plant growth shredded, the part where new leaves and flowers emerge, to be observed under a microscope to continue growing. They can track an increase of about 1,000X in the location and size of each cell at different points in the growing stages of the cell cycle. Sablowski and D’Ario negotiated shifts, checking cells every other day for two days. “We had the equipment, we had the material. All we had to do was pick up our sleeves and do a 48-hour experiment to get data that no one else had, ”says Sablowski.
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