Welcome to The Visible Embryo
  o
 
The Visible Embryo Home
   
Google  
Home--- -History-----Bibliography-----Pregnancy Timeline-----Prescription Drugs in Pregnancy---- Pregnancy Calculator----Female Reproductive System----News----Contact
 
WHO International Clinical Trials Registry Platform


The World Health Organization (WHO) has a Web site to help researchers, doctors and patients obtain information on clinical trials. Now you can search all such registers to identify clinical trial research around the world!





Home

History

Bibliography

Pregnancy Timeline

Prescription Drug Effects on Pregnancy

Pregnancy Calculator

Female Reproductive System

News

Disclaimer: The Visible Embryo web site is provided for your general information only. The information contained on this site should not be treated as a substitute for medical, legal or other professional advice. Neither is The Visible Embryo responsible or liable for the contents of any websites of third parties which are listed on this site.


Content protected under a Creative Commons License.
No dirivative works may be made or used for commercial purposes.

 

Pregnancy Timeline by SemestersDevelopmental TimelineFertilizationFirst TrimesterSecond TrimesterThird TrimesterFirst Thin Layer of Skin AppearsEnd of Embryonic PeriodEnd of Embryonic PeriodFemale Reproductive SystemBeginning Cerebral HemispheresA Four Chambered HeartFirst Detectable Brain WavesThe Appearance of SomitesBasic Brain Structure in PlaceHeartbeat can be detectedHeartbeat can be detectedFinger and toe prints appearFinger and toe prints appearFetal sexual organs visibleBrown fat surrounds lymphatic systemBone marrow starts making blood cellsBone marrow starts making blood cellsInner Ear Bones HardenSensory brain waves begin to activateSensory brain waves begin to activateFetal liver is producing blood cellsBrain convolutions beginBrain convolutions beginImmune system beginningWhite fat begins to be madeHead may position into pelvisWhite fat begins to be madePeriod of rapid brain growthFull TermHead may position into pelvisImmune system beginningLungs begin to produce surfactant
CLICK ON weeks 0 - 40 and follow along every 2 weeks of fetal development




 
Turning epigenetic marks OFF!

Epigenetics is defined as heritable changes made to a gene. But these changes are not in the DNA sequence itself — they come from methyl groups added to the DNA strand. Now, research has identified 2 proteins that can remove methylation marks from DNA.

Epigenetics play a central role in diseases in our cardiovascular system, in neurodegenerative disorders and in cancers. One of the most prominent epigenetic processes is DNA methylation, where one of the four DNA bases is marked by a recently "added" methyl group.


DNA methylation marks typically reduce the activity of surrounding genes.


Now, scientists at the Institute of Molecular Biology (IMB) in Mainz, Germany have identified a missing part of the puzzle. They understand how epigenetics marks can be removed from DNA. The research sheds new light on a fundamental DNA demethylation process important in development and disease.

A lot is known about how methyl marks are put onto DNA, but not how they are removed - demethylation is still not well understood.


Demethylation is how genes become re-activated.


In a recent study published in Nature Structural and Molecular Biology, IMB scientists have identified two proteins, Neil1 and Neil2 as important for demethylating DNA.


"These proteins [Neil1 and Neil2] are a missing link in the chain of events that explain how DNA can be efficiently demethylated."

Lars Schomacher PhD, Institute of Molecular Biology, Mainz, Germany, and first author on the paper.


DNA demethylation is known to involve proteins also involved in DNA repair. So, epigenetic gene regulation and genome maintenance are linked. Schomacher and colleagues identified in Neil1 and Neil2 two additional repair factors that protect DNA integrity when DNA is being demethylated.

It appears Neil proteins boost the Tdg protein central in DNA demethylation.

Both the Neils and Tdg are essential proteins for survival and development. Schomacher and team carried out experiments in very early frog embryos where removing either Neils or Tdg produced severe developmental problems and death before adulthood.


Failure in setting and resetting methyl marks on DNA is involved in developmental abnormalities and cancer — where cells forget what cell type they are and start to divide uncontrollably.

Understanding which proteins are responsible for DNA demethylation will help us understand more about such disease processes. And, may even provide new approaches and new treatments.


Abstract
DNA 5-methylcytosine is a dynamic epigenetic mark with important roles in development and disease. In the Tet-Tdg demethylation pathway, methylated cytosine is iteratively oxidized by Tet dioxygenases, and unmodified cytosine is restored via thymine DNA glycosylase (Tdg). Here we show that human NEIL1 and NEIL2 DNA glycosylases coordinate abasic-site processing during TET-TDG DNA demethylation. NEIL1 and NEIL2 cooperate with TDG during base excision: TDG occupies the abasic site and is displaced by NEILs, which further process the baseless sugar, thereby stimulating TDG-substrate turnover. In early Xenopus embryos, Neil2 cooperates with Tdg in removing oxidized methylcytosines and specifying neural-crest development together with Tet3. Thus, Neils function as AP lyases in the coordinated AP-site handover during oxidative DNA demethylation.

Publication
L. Schomacher et al. (2016), Neil DNA glycosylases promote substrate turnover by Tdg during DNA demethylation, Nature Structural and Molecular Biology,
DOI:10.1038/nsmb.3151

About the Institute of Molecular Biology gGmbH
The Institute of Molecular Biology gGmbH (IMB) is a center of excellence in the life sciences that was established in 2011 on the campus of Johannes Gutenberg University Mainz (JGU). Research at IMB concentrates on three cutting-edge areas: epigenetics, developmental biology, and genome stability. The institute is a prime example of a successful collaboration between public authorities and a private foundation. The Boehringer Ingelheim Foundation has dedicated EUR 100 million for a period of ten years to cover the operating costs for research at IMB, while the state of Rhineland-Palatinate provided approximately EUR 50 million for the construction of a state-of-the-art building. For more information about IMB, please visit http://www.imb.de.

About the Boehringer Ingelheim Foundation
The Boehringer Ingelheim Foundation is an independent, non-profit organization committed to the promotion of the medical, biological, chemical, and pharmaceutical sciences. It was established in 1977 by Hubertus Liebrecht (1931-1991), a member of the shareholder family of the company Boehringer Ingelheim. With the PLUS 3 Perspectives Program and the Exploration Grants, the foundation supports independent group leaders. It also endows the internationally renowned Heinrich Wieland Prize as well as awards for up-and-coming scientists. In addition, the foundation pledged to donate EUR 100 million to finance the scientific running of the IMB at Johannes Gutenberg University Mainz for ten years. In 2013, the Boehringer Ingelheim Foundation donated a further EUR 50 million to Mainz University. For more information about the Boehringer Ingelheim Foundation, please visit http://www.boehringer-ingelheim-stiftung.de.


Return to top of page

Jan 19, 2016   Fetal Timeline   Maternal Timeline   News   News Archive   



Illustrated is a chromosome unwound down to the DNA helix. Orange spheres are methyl groups
added by processes outside our inherited DNA. Methylation can "turn off" DNA when attached.
Image Credit: Imperial College London


 

 


 

Phospholid by Wikipedia