by Mark Perew
American Reporter Science Correspondent
Santa Ana, Calif.
March 22, 2001
DIVIDING AMOEBAE GET A HELPING HAND - OR FOOT
SANATA ANA, Calif., March 22, 2001 -- Beatles aren't the only critters who can sing, "I get by with a little help from my friends." An amoeba in the act of dividing into two amoebae can get stuck, too.
Israeli researchers from the Weismann Institute of Science have discovered that nearby amoebae help the struggling cells complete the division process. This science discovery will be reported in today's edition of the journal Nature.
When cells reproduce, a process called mitosis, the task normally completes uneventfully. Once in a while, though, something stalls the final step of pinching off the cell wall to make two cells where there was once only one. The two cells tug at the tiny strand still linking them together. When even that doesn't work, they seem to send out a cry for help.
Peering into their microscopes, Dr. Elisha Moses and four graduate students saw that nearby amoeba come to help sever that lingering connection. Sometimes traveling for over an hour, the nearby amoeba extend a pseudopod, or "false foot," to push the two nascent cells apart. Dr. Moses and his team have dubbed these helper amoebae as "midwives" since they aid in the birth of new sister cells.
"After careful analysis of ... the video recordings," Dr. Moses told The American Reporter in an email interview, "it became apparent that the phenomenon of 'midwives' assistance in division was quite frequent and reproducible."
The tiny single-celled creatures the Israeli group studied belong to a species called Entamoeba invadens.
The team has been in contact with two biochemists from the Max Planck Institute in Germany who have observed the same midwife phenomena in another kind of amoeba, Dictostelium discoideum. It's not known just how many kinds of organisms show this kind of behavior.
Do the midwife cells get something for their efforts? Maybe. There is some kind of chemical signal being sent out from the struggling cells. Dr. Moses and his students extracted the fluid around some still tethered cells and used that to tease other amoebae under the microscope. They found that other amoeba would follow a trail of the transferred fluid for over 30 minutes.
The secret ingredient in this fluid hasn't been precisely isolated, yet, but there are some things known about it.
"It is a big molecule which contains sugar," he reported. "Midwives may be coming to get this nutrient."
Whatever their motivation, it's clear that by helping other cells these midwives are helping themselves. Perhaps these simple, single celled creatures can serve as a reminder to the human race that lending a hand to those in need can benefit us, too.
Mark Perew is a freelance science writer. Write to himat firstname.lastname@example.org.