Published online 22 March 2001 | Nature | doi:10.1038/nib010322-11

News in Brief

Amoebic midwifery

When single-celled amoeba Entamoeba invadens has trouble tearing itself away from itself help is at hand, new research shows. Other nearby amoebae act as 'midwives', cutting the connection between the struggling would-be sisters.

When a cell divides, it pinches itself in two taking on an hourglass shape thanks to a 'contractile ring' around its equator. But in E. invadens, which lives in the guts of snakes, the ring does not fully contract, leaving the cells as Siamese twins.

The cells can separate by moving apart from each other, stretching their link to breaking point. Or midwives can barge their way through the connection.

"Midwives home in on the tube joining the two cells," says David Mirelman who, together with his colleagues at the Weizmann Institute in Rehovot, Israel, discovered the phenomenon1. "They don't go for any other area of the dividing cells."

Günther Gerisch, of the Max Planck Institute for Biochemistry in Martinsried, Germany, has seen similar behaviour in the slime mould Dictyostelium discoideum. "I think there is a good chance that [these] observations can be extrapolated to other amoeboid cells," he says.

Midwives are recruited through chemical signalling. When the researchers released culture fluid taken from around dividing amoebae into a cell culture, cells flocked towards the point of release. Not all cells heed the call; the team believes that the response may vary at different points in the amoeba's life cycle.

The precise nature of the mayday molecule is not known, but it contains sugar groups. This could explain why the midwives come to their neighbours' aid - they are getting a meal out of it.

Mirelman speculates that, in the distant past, the ability of amoebae to sense and interact with each other may have been a step on the road to the evolution of multicellular organisms. "This quorum sensing may be a primordial system," he says. 

  • References

    1. Biron,D., Libros, P., Sagi, D., Mirelman, D. & Moses, E. 'Midwives' assist dividing amoebae. Nature 410, 430 (2001). | Article | PubMed | ISI | ChemPort |