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Today, The Visible Embryo is linked to over 600 educational institutions and is viewed by more than 1 million visitors each month. The field of early embryology has grown to include the identification of the stem cell as not only critical to organogenesis in the embryo, but equally critical to organ function and repair in the adult human. The identification and understanding of genetic malfunction, inflammatory responses, and the progression in chronic disease, begins with a grounding in primary cellular and systemic functions manifested in the study of the early embryo.

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Pregnancy Timeline by SemestersFetal 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 HemispheresFemale Reproductive SystemEnd of Embryonic PeriodEnd of Embryonic PeriodFirst Thin Layer of Skin AppearsThird TrimesterSecond TrimesterFirst TrimesterFertilizationDevelopmental Timeline
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April 24, 2013--------News Archive

 
This graph shows the Hox gene relative to three species: fruitfly, mouse, and human.

 






WHO Child Growth Charts
     

 

 

 

Castor gene important in maintaining adult stem cells

Understanding exactly how stem cells form into specific organs and tissues is the holy grail of regenerative medicine. Now a UC Santa Barbara researcher has found how stem cells produce different types of "daughter" cells in Drosophila (fruit flies).

The findings appear today in the Proceedings of the National Academy of Sciences.

Denise Montell, Duggan Professor of Molecular, Cellular and Developmental Biology at UCSB, and colleagues studied the ovaries of fruit flies in order to see stem cells in their natural environment. Because these organisms are excellent models for understanding stem cell biology, researchers were able to shed light on the earliest stages of follicle cell differentiation, a previously poorly understood area of developmental biology.


"It is clear that the fundamental principles that control cell behavior in simple animals are conserved and control the behavior of our cells as well. There is so much we can learn by studying simple organisms."

Denise Montell, Duggan Professor of Molecular, Cellular and Developmental Biology, UCSB


Using a nuclear protein expressed in follicle stem cells (FSCs), the researchers found that castor, which plays an important role in specifying which types of brain cells are produced during embryonic development, also helps maintain FSCs throughout the life of the animal.

"Having identified this important protein molecule in fruit flies, we can test whether the human version of the protein is important for stem cells and their daughters as well," said Montell. "The more we know about the molecules that govern stem cell behavior, the closer we will get to controlling these cells."

Her research team placed the evolutionarily conserved castor (Cas) gene, which encodes a zinc finger protein, in a genetic circuit with two other evolutionarily conserved genes, hedgehog (Hh) and eyes absent (Eya), to determine the fates of specific cell progeny (daughters).


What's more, they identified Cas as a critical, tissue-specific target of Hh signaling, which not only plays a key role in maintaining follicle stem cells but also assists in the diversification of their progeny.


The study also shows that complementary patterns of Cas and Eya reveal the gradual differentiation of polar and stalk precursor cells at the earliest stages of their development. In addition, it provides a marker for cell fates and insight into the molecular and cellular mechanisms by which FSC progeny diverge into distinct fates.


Follicle cells undergo a binary choice during early differentiation. Those that turn into specialized cells found at the poles of egg chambers go on to make two cell types: polar and stalk.

The three genes, Cas, Eya and Hh, work in various combinations, sometimes repressively, to determine which types of cells are formed.

Cas is required for polar and stalk cell fate specification, while Eya is a negative regulator of these cells' fate. Hh is necessary for Cas to be expressed, and Hh signaling is essential to repress Eya.


"If you just had one of these markers, it was hard to tell what's going on," explained Montell. "All the cells looked the same and you had no idea when or how the process occurred. But now we can actually see how the cells acquire different identities."

Hh also plays many roles in embryonic development, adult homeostasis, birth defects, and cancer. Hh antagonists are currently in clinical trials for the treatment of several types of cancer. However, Hh signaling is important in so many different cell types and tissues that systemic delivery of such inhibitors may cause serious side effects. Therefore identifying the essential, tissue-specific effectors of Hh has the potential to lead to the identification of more specific therapeutic targets.

Someday, targeted inhibition of Hh signaling may be effective in the treatment and prevention of many types of human cancers.

Original article: http://www.ia.ucsb.edu/pa/display.aspx?pkey=2986