"What was missing from previous studies and to our knowledge had never been done in an animal model was to precisely track those changes over time and quantitatively compare them," said first author Laura Vandenberg, Ph.D., post-doctoral associate at the Center for Regenerative and Developmental Biology. Such an analysis is crucial in order to begin to understand what information is being generated and manipulated in order for a complex structure to rearrange and repair itself.
Co-author with Levin and Vandenberg was Dany S. Adams, Ph.D. Adams is a research associate professor in the Department of Biology and a member of the center.
The Tufts biologists induced craniofacial defects in Xenopus frog embryos by injecting specific mRNA into one cell at the two-cell stage of development; this resulted in abnormal structures on one side of the embryos. They then characterized changes in the shape and position of the craniofacial structures, such as jaws, branchial arches, eyes, otic capsules and olfactory pits, through "geometric morphometric analysis," which measured positioning of a total of 32 landmarks on the top and bottom sides of the tadpoles.
Images of tadpoles taken at precise intervals showed that as they aged, the craniofacial abnormalities, or perturbations, became less apparent. This was particularly true for the jaws and branchial arches. Eye and nose tissue became more normal over time but varied in ability to achieve a completely expected shape and position.
Changes in the shape and position of facial features are a normal part of development, as any baby animal shows. With age, faces elongate and eyes, nose and jaws move relative to each other. But the movement is normally slight.
In contrast, the Tufts research team found that in tadpoles with severe malformations, the facial structures shifted dramatically in order
|Contact: Kim Thurler|