PRESS-NEWS.org - Press Release Distribution
PRESS RELEASES DISTRIBUTION

Revealed: How sticky egg captures sperm

2011-08-19
(Press-News.org) Researchers have uncovered exactly how a human egg captures an incoming sperm to begin the fertilisation process, in a new study published this week in the journal Science.

The research identifies the sugar molecule that makes the outer coat of the egg 'sticky', which is vital for enabling the sperm and egg to bind together. Researchers across the world have been trying to understand what performs this task for over thirty years.

The scientists behind this study believe their work could help address some of the previously unexplained causes of human infertility and sub-fertility and be very useful for diagnosing this problem in couples who are unable to have children. It could also provide a new target for the development of natural contraceptive agents.

The international team, from the University of Missouri, the University of Hong Kong, Academia Sinica in Taiwan and Imperial College London, discovered that the sugar chain known as the sialyl-lewis-x sequence (SLeX) is highly abundant on the surface of the human egg. After experimenting with a range of synthesised sugars in the laboratory they went on to show that SLeX specifically binds sperm to an egg, and tested their findings using the outer coats of unfertilised 'non-living' human eggs.

"This exciting research is providing the first insights into the molecular events occurring at the very beginning of human life. The details we've discovered here fill in a huge gap in our knowledge of fertility and we hope they will ultimately help many of those people who currently cannot conceive," said Professor Anne Dell CBE FRS FMedSci from the Department of Life Sciences at Imperial College London, who led the team that discovered the SLeX sugars on the egg surface.

"Unravelling the composition of the sugar coat that shrouds the human egg is the culmination of many years of painstaking research by my mass spectrometry colleagues at Imperial. This endeavour was an enormously difficult task because human eggs are very tiny - about the size of a full stop - so we didn't have much material to work with."

The World Health Organization estimates that infertility affects up to 15 percent of reproductive-aged couples worldwide and almost one in every seven couples in the UK have problems conceiving a child for various clinical reasons, many of which are still unexplained by medical science.

Lead author, Dr Poh-Choo Pang, also from the Department of Life Sciences at Imperial College London, said: "We hope that our study will open up new possibilities for understanding and addressing the fertility problems that many couples face. Although clinical treatments are still a way off, we are very excited about the new research into fertility that we hope will now be possible, building on our work."

"We first proposed a model of human sperm-binding involving SLeX-like molecules on the outer covering of the human egg in 1992. Our recent studies have now confirmed that this longstanding model is correct," said corresponding author and associate professor Gary Clark, from the University of Missouri School of Medicine. "Defining how the sperm initially recognises and then penetrates the egg's sugar coat is important for the design of natural contraceptive agents and for unravelling causes of previously unexplained human infertility or sub-fertility."

A sperm 'recognises' an egg when proteins on the head of the sperm meet and match a series of specific sugars in the egg's outer coat. Once a successful match has been made, the outside surfaces of the sperm and egg bind together before they merge and the sperm delivers its DNA to the inside, fertilising the egg.

The authors of this new study used ultra-sensitive mass-spectrometric imaging technology to assess which molecules were most likely to be key in the binding process. They discovered that SLeX is abundantly found on the egg's outer coat and that it is expressed at a much higher concentration than any of the other sugars that can be found on the thick transparent shell. From these results, they deduced that SLeX was most likely to be responsible for binding with proteins on the head of the sperm.

The research team in Hong Kong tested whether SLeX was the key binding sugar using the outer coats of unfertilised and non-living human eggs, obtained by informed consent from in vitro-fertilisation patients. They carefully bisected the empty coat in a delicate procedure using a tiny knife, carried out under a powerful microscope. The scientists treated one half with a chemical that prevented the SLeX sugar from binding, to see what effect this would have on a sperm's ability to bind to the egg. When they released sperm around the bisected egg, they found that significantly fewer bound to the treated half of the egg coat than the untreated half.

"Our knowledge on sperm-egg binding in humans is limited. The identification of SLeX would enable researchers to uncover other molecules involved in this important process of human life," said Professor William Yeung from the Department of Obstetrics and Gyneacology and the Centre for Reproduction, Development and Growth at the University of Hong Kong, who led this phase of the research.

The researchers are now keen to use the findings of this study to further investigate the proteins on the head of a sperm that enable it to recognise an egg.

### This work was supported in the UK by the Biotechnology and Biological Sciences Research Council (BBSRC) and a Royal Society International Joint Project Award.


ELSE PRESS RELEASES FROM THIS DATE:

CSHL neuroscientists show activity patterns in fly brain are optimized for memory storage

2011-08-19
Large-scale imaging shows mushroom body activity patterns are sparse and randomly distributed Cold Spring Harbor, NY – We know from experience that particular smells are almost inseparable in our minds with memories, some vague and others very specific. The smell of just-baked bread may trigger an involuntary mental journey, even if for a moment, to childhood, or to a particular day during childhood. Or it may, more diffusely, remind someone of grandma. How are these associations forged in the brain and how do we remember them? A research team at Cold Spring Harbor ...

Boys reach sexual maturity younger and younger

Boys reach sexual maturity younger and younger
2011-08-19
This release is available in German. Boys are maturing physically earlier than ever before. The age of sexual maturity has been decreasing by about 2.5 months each decade at least since the middle of the 18th century. Joshua Goldstein, director of the Max Planck Institute for Demographic Research in Rostock (MPIDR), has used mortality data to prove this trend, which until now was difficult to decipher. What had already been established for girls now seems to also be true for boys: the time period during which young people are sexually mature but socially not yet considered ...

Study raises doubts about value of heart ultrasound before elective surgery

2011-08-19
TORONTO, Ont., Aug. 18, 2011_A new study has found no evidence that patients who had a heart ultrasound known as an echocardiogram before major surgery had improved survival rates one month or one year after their operation. Some groups of patients actually had worse survival rates, according to Dr. Duminda Wijeysundera, a scientist at the Li Ka Shing Knowledge Institute of St. Michael's Hospital and the Institute for Clinical Evaluative Sciences. His study, published in the British Medical Journal, adds to a growing body of evidence that echocardiograms may not be ...

UGA physicist helps uncover new data on adenine, a crucial building block of life

2011-08-19
Athens, Ga. – Early Earth's atmosphere provided little shielding for ultraviolet light from space, so many prebiotic molecules, bombarded by it and light of other wavelengths, had a hard time surviving at all. But some molecules became photostable—able to withstand the assault and thrive as building blocks of life. Five of the many molecules that survived the bombardment from UV light were the nucleic acid bases adenine, cytosine, guanine, thymine and uracil. Now, in just published research, a University of Georgia physicist and a collaborator in Germany have shown that ...

Study finds sex differences in mental illness

2011-08-19
WASHINGTON – When it comes to mental illness, the sexes are different: Women are more likely to be diagnosed with anxiety or depression, while men tend toward substance abuse or antisocial disorders, according to a new study published by the American Psychological Association. Published online in APA's Journal of Abnormal Psychology, the study looked at the prevalence by gender of different types of common mental illnesses. The researchers also found that women with anxiety disorders are more likely to internalize emotions, which typically results in withdrawal, loneliness ...

Embryo development obeys the laws of hydrodynamics

2011-08-19
Vincent Fleury, a researcher at the Paris Diderot University, studied the early stage of development when embryonic cells first form a flat sheet of cells before folding into a U-shape, resembling a folded pancake. He demonstrated that the formation of a chicken's head is a consequence of the collision between both sides of the embryo flowing at constant speed towards each other. This study captured for the first time on film highly accurate observations of how a chicken embryo evolves during its first two days of development, using time-lapse microscopy. Prior attempts ...

A quick way to grade grasses for ethanol yields

2011-08-19
This release is available in Spanish. U.S. Department of Agriculture (USDA) researchers have developed an inexpensive way to grade the ethanol potential of perennial grasses at the biorefinery's loading dock. That future has been made possible by a team of Agricultural Research Service (ARS) scientists, including Ken Vogel, Rob Mitchell, and Steve Masterson at Lincoln, Neb.; Hans Jung at St. Paul, Minn.; Bruce Dien at Peoria, Ill.; and Michael Casler at Madison, Wis. ARS is USDA's chief intramural scientific research agency, and this research supports the USDA priority ...

Headaches are common in year following traumatic brain injury, especially among females

Headaches are common in year following traumatic brain injury, especially among females
2011-08-19
New Rochelle, NY, August 18, 2011—Recurring headaches are common during the year following a traumatic brain injury (TBI), regardless of the severity of the TBI, and they tend to occur more often among females and those with a pre-TBI history of headache, according to an article in Journal of Neurotrauma, a peer-reviewed journal published by Mary Ann Liebert, Inc. The article is available free online at www.liebertpub.com/neu More than 70% of patients who had suffered a TBI reported having headaches during the first year after their injury. This finding is a result of ...

PET scans confirm effectiveness of estrogen-blocking drugs in breast cancer patients

2011-08-19
SEATTLE – For the first time, researchers at Seattle Cancer Care Alliance have demonstrated the feasibility of using serial positron emission tomography (PET) scans, using a special estrogen-containing isotope, to confirm the relative effectiveness of estrogen-blocking and estrogen-depleting therapy in patients with metastatic breast cancer. The results of the research are published online in Clinical Cancer Research. The PET scans, taken before, during and after hormonal therapy, confirmed the superior effectiveness of estrogen-receptor-blocking drugs such as tamoxifen ...

Disordered networks synchronise faster than small world networks

2011-08-19
In this study, Carsten Grabow and colleagues from the Max Planck Institute for Dynamics and Self-Organization in Göttingen, Germany, created a model to test the speed of synchronisation of complex networks in collaboration with the Warwick Complexity Centre, UK. They tested this model using three very different oscillators acting on complex networks, which are known as Kuramoto, Rössler and pulse-coupled oscillators. As a result, for all tested networks they showed that the structure of the coupling between network nodes determines the speed of synchronisation. In short: ...

LAST 30 PRESS RELEASES:

Not all Hot Jupiters orbit solo

Study shows connection between childhood maltreatment and disease in later life

Discovery of two planets sheds new light on the formation of planetary systems

New West Health-Gallup survey finds incoming Trump administration faces high public skepticism over plans to lower healthcare costs

Reading signs: New method improves AI translation of sign language

Over 97 million US residents exposed to unregulated contaminants in their drinking water

New large-scale study suggests no link between common brain malignancy and hormone therapy

AI helps to identify subjective cognitive decline during the menopause transition

Machine learning assisted plasmonic absorbers

Healthy lifestyle changes shown to help low back pain

Waking up is not stressful, study finds

Texas A&M AgriLife Research aims for better control of widespread tomato spotted wilt virus

THE LANCET DIABETES & ENDOCRINOLOGY: Global Commission proposes major overhaul of obesity diagnosis, going beyond BMI to define when obesity is a disease.

Floating solar panels could support US energy goals

Long before the L.A. fires, America’s housing crisis displaced millions

Breaking barriers: Collaborative research studies binge eating disorders in older Hispanic women

UVA receives DURIP grant for cutting-edge ceramic research system

Gene editing extends lifespan in mouse model of prion disease

Putting a lid on excess cholesterol to halt bladder cancer cell growth

Genetic mutation linked to higher SARS-CoV-2 risk

UC Irvine, Columbia University researchers invent soft, bioelectronic sensor implant

Harnessing nature to defend soybean roots

Yes, college students gain holiday weight too—but in the form of muscle not fat

Beach guardians: How hidden microbes protect coastal waters in a changing climate

Rice researchers unlock new insights into tellurene, paving the way for next-gen electronics

New potential treatment for inherited blinding disease retinitis pigmentosa

Following a 2005 policy, episiotomy rates have reduced in France without an overall increase in anal sphincter injuries during labor, with more research needed to confirm the safest rate of episiotomi

Rats anticipate location of food-guarding robots when foraging

The American Association for Anatomy announces their Highest Distinctions of 2025

Diving deep into dopamine

[Press-News.org] Revealed: How sticky egg captures sperm