‘World’s slowest Doppler effect’ found in embryo development

11 July 2014

Long-term time-lapse microscopy has elicited surprise findings about the rhythm of body segment formation during embryo development.

The scientists discovered that the development of vertebrate embryos (animals with backbones, including humans) is partly determined by a genetic Doppler effect.

The study was led by researchers at the Medical Research Council's National Institute for Medical Research (NIMR; now part of the Francis Crick Institute) in collaboration with University College London and Max Planck Institutes in Germany.

Dr Andrew Oates of NIMR explained: "The rhythm of body segment formation during the development of vertebrate embryos was thought to be set directly by the internal timing of a genetic oscillator - a genetic circuit that is expressed in a rhythmic pattern - called the 'segmentation clock'." The output of this clock appears as waves sweeping across the embryonic tissue, emerging from one end and terminating at the other end when new segments form.

Dr Oates and his team engineered zebrafish embryos to express a fluorescent 'tag' on a gene that is part of the genetic oscillator. They then made movies of these embryos as they grew during the first day of life and compared the timing of segment formation to the timing of the waves of gene expression.

Unexpectedly, this time-lapse microscopy revealed that the body segments form faster than the waves emerge in the end of the tissue.

"This paradoxical situation is caused by a Doppler effect that occurs as the end of the oscillating tissue where the segments form grows steadily into the oncoming waves," explained Dr Oates.

 

 

"While we previously thought that the rhythm of segmentation depended only on the frequency of the segementation clock, this finding shows us that the shape of the waves, as well as the rate of embryonic growth also set the rhythm."

The findings may have implications for detecting or blocking birth defects affecting the backbone - called congenital scoliosis - caused when something goes wrong with the formation of body segments in the embryo.

The paper, A Doppler effect in embryonic pattern formation, is published in Science.

  • Scientists studying vertebrate embryo development have made a surprising finding about the rhythm of body segment formation - involving a Doppler effect.
  • The Doppler effect is a physics phenomenon where the frequency of a wave changes as either its source or an observer moves. A widely given example is a siren on a car changing in pitch as it moves closer to an observer. The only previous example of a Doppler effect in biology was echo-location, used by bats and dolphins to navigate using high frequency sounds.  
  • The study findings may help researchers find ways to detect or block congenital scoliosis - a birth defect of the backbone that's caused by something going wrong with the formation of body segments in the embryo.