«Our studies suggest that the local auxin signals can be communicated over long distances using
calcium waves in order to generate an auxin signal also in target cells located far away,» Hedrich says.
Whenever a mouse moves one of its legs, Nimmerjahn and his colleagues can see a little burst
of calcium waves.
«We were able to see for the first time, in 3D,
where calcium waves come from in cardiac myocytes,» he explains.
Piece three: They can produce outputs — neurotransmitters and perhaps
even calcium waves that spread to other astrocytes.
The researchers theorize that the segmentation clock works like other excitable biological systems that require certain thresholds to be met before sparking an action, such as neurons firing and
calcium waves traveling across heart cells.
They find that two different stimulus signals can produce two different patterns
of calcium waves (that is, two different responses) in an astrocyte.
Examination under a fluorescence microscope revealed that
this calcium wave reaches the root tip already within a few minutes.
In a final set of experiments, the researchers showed that
the calcium waves are generated by a neurotransmitter called glutamate, which is released from damaged cells.
Adding a drug that blocked
the calcium wave prevented microglia from migrating to the injury site, the team reports today in Developmental Cell.
If
the calcium waves really are so important, for instance, you would expect that a genetically engineered mouse that couldn't make calcium waves would be one sorry rodent.
The new findings, says Peri, implicate
the calcium waves as potential targets for drug treatments.
Kirchhoff is skeptical, however, that
the calcium wave could be a drug target.