Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Unlocking the key to human fertility

04.08.2009
Scientists at Leeds and Bradford have discovered a unique ‘DNA signature’ in human sperm, which may act as a key that unlocks an egg’s fertility and triggers new life.

Drs David Miller and David Iles from the University of Leeds, in collaboration with Dr Martin Brinkworth at the University of Bradford, have found that sperm writes a DNA signature that can only be recognised by an egg from the same species. This enables fertilisation and may even explain how a species develops its own unique genetic identity.

Dr Iles says, “What we have discovered is a previously unrecognised DNA packaging ‘signature’ in mammalian sperm that may be essential for successful fertilisation of the egg and development of the embryo. We think it may also be ancient in origin.”

Without the right ‘key’, successful fertilisation either cannot occur, or if it does, development will not proceed normally. Notably, disturbances in human sperm DNA packaging are known to cause male infertility and pregnancy failures.

This ‘lock and key’ mechanism has other profound implications. Not only does it explain why some otherwise healthy men produce sperm that is sterile, but it also explains how different species evolve and retain their own identity.

Says Dr Miller, “Up until now, Doctors have struggled to understand idiopathic male infertility. Our latest research offers a plausible explanation for why some sperm malfunction or fail to function correctly.”

If the DNA carried by a sperm cell was unwound and stretched out, it would actually measure more than a metre in length. In order to fit all this DNA into the microscopic space within the head of the sperm cell, the DNA needs to be very tightly coiled, or packaged. The Leeds study showed that in human and mouse sperm, not all of the DNA is packaged in the same way. Whilst most of the paternal DNA is compressed in an extremely compact fashion, some is packaged less tightly.

“There is a definite pattern to the way DNA is packaged in sperm cells and we can see that this pattern is the same in unrelated fertile men. It is different in the sperm of infertile men. This implies that there is a significance to the packaging of DNA that has a direct relevance to male fertility,” says Dr Iles.

Detailed analyses of the DNA in the ‘open’, less tightly packaged conformation, showed this DNA carries much of the information critical for activating genes essential for directing the development of the embryo. Further investigations showed the same conformation to exist in the sperm of several unrelated human donors and remarkably, highly similar packaging patterns to exist in the sperm of mice.

DNA regions in the ‘open’ conformation may therefore be more vulnerable to damaging toxins, such as those in cigarette smoke and certain anti-cancer drugs, than those that are tightly packaged. As Dr Brinkworth says, “this might mean that anything capable of causing genetic damage to sperm could have particular significance for the development of the embryo”.

The findings also help explain why inter-species breeding is so rarely successful.

Where the locks and keys of two species do not match, however similar their DNA is, no viable offspring can be born. Occasionally, for example, with horses and donkeys, offspring are produced - but because the sperm and egg signatures are incompatible, their development as embryos is abnormal and any offspring are almost always infertile.

The research team believes that the same mechanism must also have played a role during human evolution. In the ancient history of mankind, Neanderthals co-existed with modern humans over many thousands of years. Sexual encounters between these two closely related species cannot be ruled out, yet there is no evidence in our DNA of a legacy from such couplings. It is possible that if offspring were produced, they either did not survive long or if they did, they were unable to breed.

Further information from
Jo Kelly, Campuspr Ltd: tel 0113 258 9880, mob 07980 267756, email jokelly@campuspr.co.uk

Guy Dixon, University of Leeds press office: tel 0113 343 8299, email g.dixon@leeds.ac.uk

Notes to editors

The research was funded by a grant from the BBSRC and the resulting paper, Endonuclease-sensitive regions of human spermatozoal chromatin are highly enriched in promoter and CTCF binding sequences is to be published in the forthcoming issue of Genome Research. It can be found online at

http://genome.cshlp.org/content/early/2009/07/07/gr.094953.109

The findings are the result of a collaborative study between Drs David Miller and David Iles in the Faculties of Medicine and Biological Sciences at the University Leeds, alongside Dr Martin Brinkworth of the Medical Biosciences Research Focus Group at the University of Bradford and partners in Germany and the United States.

The Faculty of Biological Sciences at the University of Leeds is one of the largest in the UK, with over 150 academic staff and over 400 postdoctoral fellows and postgraduate students. The Faculty was ranked 4th in the UK (Nature Journal, 457 (2009) doi:10.1038/457013a) based on results of the 2008 Research Assessment Exercise (RAE). The RAE feedback noted that “virtually all outputs were assessed as being recognized internationally, with many (60%) being internationally excellent or world-leading” in quality.

The Faculty’s research grant portfolio totals some £60M and funders include charities, research councils, the European Union and industry. www.fbs.leeds.ac.uk

The 2008 Research Assessment Exercise showed the University of Leeds to be the UK's eighth biggest research powerhouse. The University is one of the largest higher education institutions in the UK and a member of the Russell Group of research-intensive universities. The University's vision is to secure a place among the world's top 50 by 2015.

Dr. David Iles | EurekAlert!
Further information:
http://www.leeds.ac.uk

More articles from Life Sciences:

nachricht How brains surrender to sleep
23.06.2017 | IMP - Forschungsinstitut für Molekulare Pathologie GmbH

nachricht A new technique isolates neuronal activity during memory consolidation
22.06.2017 | Spanish National Research Council (CSIC)

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Quantum thermometer or optical refrigerator?

23.06.2017 | Physics and Astronomy

A 100-year-old physics problem has been solved at EPFL

23.06.2017 | Physics and Astronomy

Equipping form with function

23.06.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>