A Caenorhabditis elegans worm squirms its way through a compost heap, sensory neurons in its nose helping it navigate oxygen and carbon dioxide cues as it searches for food.
The lab of Harvard Medical School geneticist Max Heiman studies these neurons to illuminate nervous system development and uncover clues about how things go awry in humans, leading to neurodevelopmental disorders and neurodegeneration.
In its latest finding, reported online in Development, Heiman’s group discovered a new way that these neurons and their sensory endings, called dendrites, grow.
The team found that the carbon dioxide-sensing neuron, BAG, shown above in blue, and the oxygen-sensing neuron, URX, shown in green, attach first to the developing worm’s nose, then stretch backward as the embryo grows and lengthens—a process known as retrograde extension.
“We’ve seen this kind of ‘backwards’ dendrite growth before in C. elegans, but URX and BAG are doing it with different molecules,” said Heiman, associate professor of genetics and of pediatrics in the Blavatnik Institute at HMS and Boston Children’s Hospital, and senior author of the study. “Retrograde extension has recently been seen in zebrafish as well. How many ways of doing it are there?”
Even more striking, the researchers revealed that URX and BAG attach to the same glial cell (shown in purple) in the nose.
