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Pregnancy Timeline by SemestersFemale Reproductive SystemFertilizationThe Appearance of SomitesFirst TrimesterSecond TrimesterThird TrimesterFetal liver is producing blood cellsHead may position into pelvisBrain convolutions beginFull TermWhite fat begins to be madeWhite fat begins to be madeHead may position into pelvisImmune system beginningImmune system beginningPeriod of rapid brain growthBrain convolutions beginLungs begin to produce surfactantSensory brain waves begin to activateSensory brain waves begin to activateInner Ear Bones HardenBone marrow starts making blood cellsBone marrow starts making blood cellsBrown fat surrounds lymphatic systemFetal sexual organs visibleFinger and toe prints appearFinger and toe prints appearHeartbeat can be detectedHeartbeat can be detectedBasic Brain Structure in PlaceThe Appearance of SomitesFirst Detectable Brain WavesA Four Chambered HeartBeginning Cerebral HemispheresEnd of Embryonic PeriodEnd of Embryonic PeriodFirst Thin Layer of Skin AppearsThird TrimesterDevelopmental Timeline
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November 6, 2012--------News Archive Return to: News Alerts

Normal juvenile C. elegans worm in which all cell nuclei of the intestine are filled
with a glowing green fluorescent protein. In embryos in which cell destiny has been
changed (not shown in the image), cells that would normally be part of the brain
or skin become intestine and show the green signal.

Credit: M. Maduro

WHO Child Growth Charts

       

A Gift for the Tin Man?

Scientists have discovered that breaking a biological signaling system in an embryo allows them to change the destiny of a cell – and could lead to new ways of making replacement organs

The discovery was made in the laboratory of Joel H. Rothman, a professor in the Department of Molecular, Cellular, and Developmental Biology at UC Santa Barbara, and were reported in the interdisciplinary journal Genes and Development. The work was carried out by Ph.D student Nareg Djabrayan, in collaboration with Rothman and two other members of the laboratory, Ph.D student Erica Sommermann and postdoctoral fellow Nathaniel Dudley.

"At some point along the way toward becoming part of a complete individual, cells become destined to choose a particular identity and long-term profession," Rothman noted. "Once a cell chooses who it will be, it locks onto that identity for the remainder of its life."

A cell that is destined to become a heart cell functions exclusively in the heart until it dies, and never chooses later to change jobs by becoming, for example, a brain cell. "If Oz's wizard possessed the powers he claimed, and had a spare brain lying around, he could switch it to a heart as a gift for the Tin Man. And he could reverse the trick for the Scarecrow," Rothman said.

Similarly, the researchers have found a way to unlock cells' destinies and lead them to take on a new profession.

The scientists found that a widely used cell signaling system, known as "Notch" signaling, causes cells to commit to a particular occupation, such as a skin or brain cell. When they blocked the signal by genetic manipulation, the researchers discovered that they could force a cell to change its destiny, such that they instead became cells of the intestine.

"We found that we could break the signal in such a way that cells would follow their usual destinies, but were somehow less committed to doing so: We could convince them to change professions long after they would normally refuse to do so," Rothman said.

The scientists made the discovery by harnessing the genetics of a tiny nematode worm known as C. elegans, a model animal that has become famed in fundamental studies in biomedicine, and has been the subject of six Nobel prizes.


The researchers discovered that shutting off
the Notch signal in early embryos made it possible
for them to change the destiny of cells much later on,
at a stage when they normally could not.

"The later cells seemed to remember what had
happened to their great-grandparent cells.

Imagine if the experience of your great-grandparents
predestined you to become a lawyer, dentist,
or coal miner, and you could not choose to
change your professional destiny.

That is what is happening to cells whose
cellular ancestors received the Notch signal."


Joel H. Rothman
professor
Department of Molecular, Cellular, and Developmental Biology
University of California, Santa Barbara


The discovery could someday help scientists develop new ways to produce tissues and organs in the laboratory that could be used to replace a patient's injured, diseased, or aged organs.

By unlocking a cell's normal destiny, it may be possible to change it into an altogether different type of cell that could be used to grow a new organ for a patient –– or perhaps, a Tin Man.

The research was supported by the National Institute of Child Health and Human Development and the California Institute of Regenerative Medicine.

Original article: http://www.ia.ucsb.edu/pa/display.aspx?pkey=2867