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View Full Version : Fruitfly has human-like stem cells: study



Leif
12-08-2005, 09:56 AM
http://english.peopledaily.com.cn/200512/08/eng20051208_226606.html



Adult fruitflies have the same stem cells controlling cell regulation in their gut as humans do, a research team reported on Wednesday.

The study is important for understanding digestive disorders, including some cancers, and for developing cures, said scientists at the Carnegie Institution. Their findings appeared in the Dec. 7 early online edition of the journal Nature.

"The fact that fruitflies have the same genetic programming in their intestines as humans, strongly suggests that we were both cut from the same evolutionary cloth more than 500 million years ago," stated Benjamin Ohlstein, leading author of the paper.

It may come as a surprise, but insects have the same basic structure to their gastrointestinal tract as vertebrates. They have a mouth, an esophagus, the equivalent to a stomach, and large and small intestines.

The researchers looked at their small intestines, where food is broken down into its constituent nutrients for the body to absorb.

They focused on two cell types -- cells that line the small and large intestines in a single layer to help break up and transport food molecules, called enterocytes; and cells that produce peptide hormones, whose functions include regulation of gastric motility as well as growth and differentiation of the gut (enteroendocrine cells).

In vertebrates, cells of the intestines are continually replenished by stem cells.

To see if stem cells were at work in the gut of the fruitfly, the researchers labeled each of the two cell types of interest and observed how successive generations of the cells transformed.

They found for the first time that the fly cell types are replenished by stem cells like the vertebrates. Moreover, like vertebrates, the stem cells are multipotent, which means that they can turn into different cell types.

The researchers also found that notch signaling is essential for flies to control which intestinal cells form, just like for humans. Notch signaling was also found to instruct stem cells themselves, a role that has as yet to be identified for Notch signaling in vertebrates.

"Thus, the midgut progenitor's default state is proliferation, which is inhibited through the Notch signaling pathway," the researchers wrote in the paper.

They noted that studying a process in a model system such as the fruitfly can greatly accelerate the understanding of corresponding human process.