Skip Navigation
Search

The next generation

June 20, 2005 By Roxanne Khamsi This article courtesy of Nature News.

The time is ripe for news about everything from cloning to fertility research, as experts convene for the annual meeting of the European Society of Human Reproduction and Embryology in Copenhagen this week. Roxanne Khamsi sends regular reports from the co

Please log in to rate this page.

View Comments

Day 3: Soy and premature sperm

Could a naturally occurring chemical in soy products put a quick end to the ability of sperm to fertilize an egg? Lynn Fraser of Kings College in London thinks so. But while I'm perfectly convinced this happens in the test tube, it's another matter altogether whether it happens inside real people - which no one yet knows. I, for one, won't be changing my dietary habits any time soon...

Fraser has previously shown that genistein, which mimics the effects of the female hormone oestrogen, can cause mouse sperm to prematurely activate and "burn out" before encountering the egg. Her most recent study shows the same effect on human sperm.

The head of a sperm contains a cap that normally ruptures and releases a cocktail of enzymes to help it dock and combine with an egg. In the laboratory dish, relatively low levels of genistein activate this process with alarming speed, having a big impact even within the first hour. This might mean that women eating products that contain soy, such as tofu and some legumes, could unknowingly be reducing their ability to conceive. Fraser speculates that the genistein in these foods may present an added obstacle for sperm upon entering a female body, causing their caps to rupture too soon.

Her team believes that this subtle premature activation of sperm could perhaps help to explain the decline in male fertility that scientists have reported. Many studies have found that high levels of oestrogen-like compounds affect male animals' sperm production directly. But Fraser explains that the dosages of these compounds far exceed anything found in a person's normal diet. "It's the equivalent of using a sledge-hammer to crack a nut," she says. Quite an appropriate analogy, I think.

But I also worry that some men might jump on these preliminary results and use them to blame their female partners for any unexplained difficulties couples face when trying to conceive a child - which would be jumping the gun a bit. Women already face heavy scrutiny over the lifestyle choices they make that could affect their fertility, such as deciding to make their careers a priority and having children later in life. I hope that tofu-loving females don't become frowned upon by their partners.

Anyway, until someone tells me that women in Asian countries have reduced fertility, and that this relates to their soy-rich diet, I wouldn't bother to pick the tofu out of my stir-fry.

Day 3: Less is more

Less could be more when it comes to having babies, according to a bunch of studies being presented here.

One such study involved a group of Belgian researchers looking at whether taking a biopsy of one or two cells from the early embryo affects the accuracy of genetic tests done before embryos are implanted in the womb during IVF. Turns out it's just as accurate with one cell as with two.

No one really knows yet what that means. Is it better for mom or baby to only remove one cell? It might be. Maybe taking more cells inflicts damage on the embryo's later development, they say, though they have yet to study that effect.

Other studies have looked at the idea of transplanting single rather than multiple embryos during IVF treatments. It's already well known that trying to rear twins or triplets carries more risk than trying to raise a single child. But one study here documents how babies resulting from a multiple embryo transfers also face more risk, even if only a single child is born.

This could be because many of these babies had a "vanishing twin" says Anja Pinborg of the University of Copenhagen. That's a twin who died very early in the pregnancy, often before the mother ever knew there was a second child. This could negatively impact the neurological development of the surviving fetus, Pinborg and her colleagues say.

So the concept of economy in implanting embryos gets another boost from experts here.

Day 3: Don't hurt him

Late into the last day of the meeting, Seoul National University biologist Shin Yong Moon, well known for helping to produce embryonic stem cells from a cloned human embryo, arrives to deliver a talk.

A few hours before his schedules appearance, a small crowd of listeners gathers around hoping for a sneak peak into his findings. The impromptu audience of reporters waits with anticipation. Have they something equally shocking and exciting to report? What's the news from what is potentially the world's premier cloning team??? Well, um, nothing really. Moon has come to Copenhagen with no new, unpublished findings to report. "You may kill me," Moon jokes. But, he pleads, it has only been a month since they last reported results. Things don't move that quickly in the world of science.

And so with a whimper rather than a bang, I'm heading home.

Day 2: Chill out

Today starts off with a presentation of some chilling results. Stanley Leibo of the Audubon Center for Research of Endangered Species in New Orleans is talking about vitrification, a ultra-fast way to cool human egg for preservation that avoids some of the damage to the cell. The process may involve plunging women's eggs into super-cold liquid nitrogen, but among the attendees of the conference it's a hot topic. Only last month a Taiwanese scientists reported a woman had become pregnant after that they successfully unfroze and fertilized her once vitrified eggs.

Leibo describes vitrification as a way to "out-race injury" to these reproductive cells. By speeding up the cooling process, medical experts would reduce the chance that ice crystals form and sabotage the cell. And he claims that very recent studies in mice suggest the process could be improved by reducing the amount of protective solution used to prep the cells before dipping them in the suspending the liquid nitrogen. So preserving a woman's fertility may be easier in the near future.

Day 1: Don't be afraid

Fear not! That's a good life lesson, in general. And now Gert Holstege of the University of Groningen in the Netherlands gives us added reason to approach events in life without trepidation. He claims the mental state of being fearless is key to enjoying sex -- at least according to evidence from female test subjects.

While flashing images of human brain scans on his laptop, he points to the amygdala, an almond-shaped lump thought to somehow control emotions like anxiety. Holstege took these images of women's brains as they reached orgasm (thanks to manual stimulation from their partners who sat nearby, for those who really want to know) and found decreased activity in the amygdala at the crucial point. This, he says, means that deactivation of the brain's fear pathways concurred with - and perhaps facilitated - their ability to climax. The proof is from the control experiment: when women faked an orgasm no such change was observed in their amygdala.

Day 1: A hint of a happy ending

Though much of the work presented here in Copenhagen dwells on the very earliest intimations of life, focusing on eggs, sperm and their test-tube combinations, some of it also centers on happy endings.

Siobhan Quenby of the University of Liverpool, UK smiles a lot as she talks about how a woman who had 19 miscarriages went on to have a baby after receiving steroid treatments. She found that giving the steroid known as prednisolone, which is commonly used to fight ailments such as asthma, reduced a type of white blood cell in the uterus that's linked to recurrent miscarriages. A second woman in the trial has become successfully pregnant too.

Quenby has yet to do a scientific study using a control group of participants, and she notes that two out of the 29 women who agreed to take prednisolone miscarried again. But Quenby believes the initial results of administering the steroid offer hope at a time when much remains unknown about why women undergo this painful loss. "A little bit of an idea is better than nothing," she says. It's a promising start at the very least.

Comments

User Tools [+] Expand

User Tools [-] Collapse

Pinterest button

Favorites

Please log in to add this page to your favorites list.



Need Assistance?

If you need help or have a question please use the links below to help resolve your problem.