Scientists at Taiwan’s Academia Sinica have identified a new form of cell division that occurs without the replication of DNA, challenging the scientific consensus on one of the most basic biological processes.
Since the 19th century, scientists have known of only two main types of cell division in animals — meiosis in germ cells (sperm or egg cells) and mitosis in somatic cells, which comprise all other cells in the body.
In a new paper published in the British scientific journal Nature, however, an Academia Sinica team described a previously unknown form of cell division which, unlike mitosis, does not involve the duplication of DNA.
The team, led by Chen Chen-hui (???), assistant research fellow at the academy’s Institute of Cellular and Organismic Biology, held a press conference on Monday to explain their findings.
To conduct its research, Chen’s team used a custom-made computer tagging system to color, and then track, individual cells on zebrafish larvae as they developed.
In order to do so, the researchers had to catch and anaesthetize the 0.5-centimeter fish every 12 hours, and then photograph them under a high-powered microscope.
They discovered that during a specific stage in the fishes’ growth, some of the outer layers of their skin cells underwent up to two rounds of cell division (one cell becoming four cells) by splitting, rather than duplicating, their DNA.
The team believes this phenomenon, called asynthetic fission, is a temporary measure used to expand the coverage of epithelial cells, or outer skin cells, during a period of rapid growth, Chen said.
According to a video produced by Nature, the process happens so quickly that cells even appeared to make “mistakes,” such as not cleanly separating the DNA between the new cells.
Within a few weeks, however, the zebrafish had gotten rid of the unusual cells and replaced them with regular cells containing normal amounts of DNA, the video noted.
While Chen’s team said they were still in the early stages of understanding the process, they speculated that this mode of cell proliferation could occur in contexts other than zebrafish skin expansion.
The team’s article, titled “Skin cells undergo asynthetic fission to expand body surfaces in zebrafish,” was published in Nature on April 27.
The journal’s video on the research, “A new kind of cell division,” was released on Sunday.
Source: Focus Taiwan News Channel