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A report in the May issue of the journal Developmental Dynamics reveals that biologists from the Tufts University have, for thefirst time, discovered a "self-correcting" mechanism by whichdeveloping organisms recognize and repair head and facialabnormalities. This is the first time that this kind of flexible, correctiveprocess has been rigorously analyzed through mathematical modeling. The study demonstrates that developing organisms are notgenetically "hard-wired", but that the process is, instead, moreflexible and robust. By using a tadpole model with a set ofpre-determined cell movements that result in normal facialfeatures, they demonstrated that cell groups can measure theirshape and position in relationship to other organs, as well asperforming the required movements and remodeling functions in orderto compensate for important abnormalities in patterns. Senior researcher, Michael Levin, Ph.D., director of the Center forRegenerative and Developmental Biology in Tufts University's Schoolof Arts and Sciences explained: "A big question has always been, how do complex shapes like theface or the whole embryo put themselves together? We have foundthat when we created defects in the face experimentally, facialstructures move around in various ways and mostly end up in theircorrect positions. This suggests that what the genome encodesultimately is a set of dynamic, flexible behaviors by which thecells are able to make adjustments to build specific complexstructures. If we could learn how to bioengineer systems thatreliably self-assembled and repaired deviations from the desiredtarget shape, regenerative medicine, robotics, and even spaceexploration would be transformed." Earlier research had discovered self-correcting mechanisms in otherembryonic processes, yet never in the face. These mechanisms hadnot been analyzed mathematically to shed a light onto thecorrective process' precise dynamics. Leading researcher, Laura Vandenberg, Ph.D., a post-doctoralassociate at the Center for Regenerative and Developmental Biologysaid: "What was missing from previous studies - and to our knowledge hadnever been done in an animal model - was to precisely track thosechanges over time and quantitatively compare them." An analysis like this is vital for gaining insight into whatinformation is being generated and manipulated so that a complexstructure can rearrange and repair itself. The team of biologists made one side of the embryos abnormal byinjecting specific mRNA into one cell at the two-cell stage ofdevelopment, which induced craniofacial defects in Xenopus frogembryos. They then characterized changes of the craniofacial structures interms of their shape and position, including jaws, eyes, branchialarches, otic capsules and olfactory pits by performing a 'geometricmorphometric analysis' that measures the position of 32 landmarkson tadpoles' top and bottom sides. By taking images of tadpoles at precise intervals, the researchersobserved that the craniofacial abnormalities (perturbations), inparticular, in the jaws and branchial arches became less apparentas the tadpoles aged. They also noted that the tadpoles' eye andnose tissue became more normal over time, although they did notevarious differences in achieving a completely expected shape andposition. In any baby animal it is a normal part of development that facialfeatures change in terms of their shape and position. As the animalgets older, their faces elongate and their eyes, nose and jaws growin relation to each other, even though the movement is generallyfairly marginal. The team observed, however, that in tadpoles with severemalformation, a major dramatic shift occurred in the facialstructures in order to repair those malformations. They stated thatit appeared as if the system was able to detect deviations from thenormal state and perform corrective actions that would nottypically take place. "We were quite astounded to see that, long before they underwentmetamorphosis and became frogs, these tadpoles had normal lookingfaces. Imagine the implications of an animal with a severe 'birthdefect' that, with time alone, can correct that defect." The biologists state that the findings were consistent with aninformation exchange process in which a structure triangulates itsdistance and angle from a stable reference point. They say thatalthough further studies are required, they suggest exchanging'pings', i.e. signals that contain information between an'organizing center' like the brain and neural network andindividual craniofacial structures. The researchers highlight the fact that birth defects, such ascleft lips, cleft palate and microphthalmia affect over 1 in 600births. New approaches of correcting these birth defects thatbelong to the category of congenital malformations of craniofacialstructures could potentially be corrected in humans by conductingfurther studies at the molecular level, which would shed more lighton the "face-fixing" dynamics. Levin concluded: "Such understanding would have huge implications not only forrepairing birth defects, but also for other areas of systemsbiology and complexity science. It could help us build hybridbioengineered systems, for synthetic or regenerative biology, orentirely artificial robotic systems that can repair themselvesafter damage or reconfigure their own structure to match changingneeds in a complex environment." Written By Petra Rattue Copyright: Medical News Today Not to be reproduced without permission of Medical News Today Additional References Citations. 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