Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Fertilized egg cells trigger and monitor loss of sperm’s epigenetic memory

02.12.2016

Scientists from the Institute of Molecular Biotechnology (IMBA) in Vienna, Austria, have discovered how an embryo’s genomic integrity is safeguarded during the first 24 h after fertilization. Insights into this mechanism have implications for improving in vitro fertilization.

The events triggered when sperm meets an egg are not only life changing for the parents but deeply fascinating from a scientific point of view, too.


A mouse zygote in which the maternal genome remains highly methylated (5mC, magenta) while the paternal genome looses its methylation shortly after fertilization.

The mother of all cells

Following fertilization, DNA from the mother’s egg cell and the father’s sperm cell constitute the genetic blueprint of the single-cell embryo or zygote. The incoming paternal DNA contains modifications that facilitate an “epigenetic memory” of its sperm state. Proteins provided by the fertilized egg act to largely erase this memory in order to generate a totipotent embryo that can give rise to a whole new individual.

The mechanisms underlying natural reprogramming to totipotency are remarkably efficient but remain poorly understood. “To put this into perspective, reprogramming to induced pluripotency in cell culture takes several days to weeks whereas reprogramming to totipotency in zygotes occurs in less than 24 h”, says Kikuë Tachibana-Konwalski, who devotes her laboratory’s research to understanding the molecular secrets of egg cells and zygotes.

New life, new epigenetics

Reporting research in the scientific journal Cell, Vienna-based scientists from the Institute of Molecular Biotechnology (IMBA) have discovered that not only do fertilized egg cells trigger epigenetic reprogramming of sperm DNA but this process is closely monitored to safeguard genomic integrity.

“When the sperm enters the egg cell, the densely compacted male chromatin has to be entirely ‘unpacked’ and restructured around protein scaffolds called histones,” explained Sabrina Ladstätter, first author of the study.

“Using fertilized mouse eggs, we showed that the egg cell actively triggers demethylation of the paternal DNA – in other words, it initiates epigenetic reprogramming by stripping any previous epigenetic memory passed on from the father. This allows the zygote to start afresh and create its own epigenetic memory and life history. This process is not without risks: demethylation can cause lesions in the DNA that can be fatal for the new organism. It is known that these lesions can lead to chromosome fragmentation, embryo loss or infertility.”

A molecular checkpoint

The researchers identified a surveillance mechanism that not only monitors DNA lesions caused by epigenetic reprogramming but also fixes the damage. They revealed that lesions in the paternal DNA caused by demethylation activate a zygotic “checkpoint” that prevents cell division until these lesions are repaired. This mechanism therefore ensures that reprogramming is completed within one cell cycle and protects genomic integrity at the volatile single-cell embryo stage. Interestingly, they also found that the conditions under which embryos are cultured affect the stringency of the checkpoint response.

Hope for better IVF treatments?

“Our findings have potential implications for improving in vitro fertilization techniques,” said Kikuë Tachibana-Konwalski, senior author of the study and a group leader at IMBA. “It will be exciting to explore how cell culture conditions enhance the zygote’s intrinsic surveillance and repair mechanisms, thus leading to better quality embryos and potentially more successful pregnancies.”

Original Article:
“A surveillance mechanism ensures repair of DNA lesions during zygotic reprogramming”, Ladstätter, Tachibana-Konwalski, Cell: http://dx.doi.org/10.1016/j.cell.2016.11.009

Weitere Informationen:

Press picture: http://de.imba.oeaw.ac.at/index.php?id=516

Mag. Ines Méhu-Blantar | idw - Informationsdienst Wissenschaft

More articles from Life Sciences:

nachricht Rochester scientists discover gene controlling genetic recombination rates
23.04.2018 | University of Rochester

nachricht One step closer to reality
20.04.2018 | Max-Planck-Institut für Entwicklungsbiologie

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Molecules Brilliantly Illuminated

Physicists at the Laboratory for Attosecond Physics, which is jointly run by Ludwig-Maximilians-Universität and the Max Planck Institute of Quantum Optics, have developed a high-power laser system that generates ultrashort pulses of light covering a large share of the mid-infrared spectrum. The researchers envisage a wide range of applications for the technology – in the early diagnosis of cancer, for instance.

Molecules are the building blocks of life. Like all other organisms, we are made of them. They control our biorhythm, and they can also reflect our state of...

Im Focus: Spider silk key to new bone-fixing composite

University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.

Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.

Im Focus: Writing and deleting magnets with lasers

Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.

Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...

Im Focus: Gamma-ray flashes from plasma filaments

Novel highly efficient and brilliant gamma-ray source: Based on model calculations, physicists of the Max PIanck Institute for Nuclear Physics in Heidelberg propose a novel method for an efficient high-brilliance gamma-ray source. A giant collimated gamma-ray pulse is generated from the interaction of a dense ultra-relativistic electron beam with a thin solid conductor. Energetic gamma-rays are copiously produced as the electron beam splits into filaments while propagating across the conductor. The resulting gamma-ray energy and flux enable novel experiments in nuclear and fundamental physics.

The typical wavelength of light interacting with an object of the microcosm scales with the size of this object. For atoms, this ranges from visible light to...

Im Focus: Basel researchers succeed in cultivating cartilage from stem cells

Stable joint cartilage can be produced from adult stem cells originating from bone marrow. This is made possible by inducing specific molecular processes occurring during embryonic cartilage formation, as researchers from the University and University Hospital of Basel report in the scientific journal PNAS.

Certain mesenchymal stem/stromal cells from the bone marrow of adults are considered extremely promising for skeletal tissue regeneration. These adult stem...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

IWOLIA: A conference bringing together German Industrie 4.0 and French Industrie du Futur

09.04.2018 | Event News

 
Latest News

Structured light and nanomaterials open new ways to tailor light at the nanoscale

23.04.2018 | Physics and Astronomy

On the shape of the 'petal' for the dissipation curve

23.04.2018 | Physics and Astronomy

Clean and Efficient – Fraunhofer ISE Presents Hydrogen Technologies at the HANNOVER MESSE 2018

23.04.2018 | Trade Fair News

VideoLinks
Science & Research
Overview of more VideoLinks >>>