MONTREAL, CANADA—When taking a dip this summer you will probably swallow tens, possibly hundreds, of microscopic plankton called choanoflagellates. These common organisms have led to an uncommon insight into how multicellular organisms might have evolved. Bacteria can prompt single-celled choanoflagellates to divide into multicellular versions of themselves, University of California (UC), Berkeley, biologist Nicole King reported last week here at the 71st annual meeting of the Society for Developmental Biology. King hopes the work will prompt biologists to look more closely at the role of microorganisms in the evolution of multicellularity.
To the untrained eye, choanoflagellates look like animals. But they are less complex—the closest living relatives of animals but on an older branch of the tree of life. As such, these organisms can provide clues about what early animals looked like and can help reconstruct the events from more than 600 million years ago that led to the incredible diversity of the animal kingdom.
To investigate the transition to colony life, King decided to sequence the genome of a colony-forming choanoflagellate and compare it with the genome of a unicellular individual. But before sequencing, she asked undergraduate Richard Zuzow to purge the sample of everything but the plankton itself. When Zuzow added antibiotics to get rid of any bacteria, the choanoflagellate colonies disappeared. At first, “I didn’t believe him,” King recalls. But with repeated tests, she became convinced that “the bacteria are the important part of the [multicellular] story,” she says
To the mournful tune of a lone saxophone scientists marched through the streets of Ottawa and onto Canada’s Parliament Hill to protest a glut of cuts to government research labs and — they say — a lack of evidence-based decision making in the Canadian government.
The 10 July rally drew an estimated 2000 scientists, graduate students and their supporters to the sunny capital, many of them dressed in white lab coats; smaller protests took place in other cities across the country including in Regina, Guelph and Calgary.
The protesters accuse the Harper government of shutting down Canadian scientific agencies because they threaten to expose the environmental impact of fossil fuel extraction, particularly from the Alberta oil sand, and of mining on Canadian lakes and rivers.
“That’s a story that [Canadian Prime Minister] Stephen Harper doesn’t want you to hear,” said Maude Barlow, the National Chairperson of the Council of Canadians, an advocacy organization that works to promote green water and energy policies, in her speech outside the Houses of Parliament.
Cuts to the Canadian federal budget this year have meant the closure of various scientific programs, including the Experimental Lakes Area (ELA), a 44-year-old research station that houses a system of 58 lakes in northwestern Ontario. ELA provided the first evidence for acid rain, and diagnosed the effects of mercury pollution and synthetic hormones on aquatic life.
“Society has learned a tremendous amount [from these lakes],” said Jeff Hutchings, a biologist at Dalhousie University in Halifax and the President of the Canadian Society for Ecology and Evolution. “It [will] be tremendous loss, and not just to Canadian society, because [the lakes] generates knowledge of importance to any country with lakes,” he told Nature.
The cuts are imminent. The first of Canadian government scientists will lose their positions at the beginning of August , and the closure of the ELA is slated for April next year.
“The government would like to have universities take over this facility, [but] in this time frame that almost certainly won’t happen…[the facility] will [therefore] presumably be moth-balled, taking with it decades of internationally renowned research,” said Hutchings.
In response to today’s protest, Gary Goodyear, Canada’s minister of state for science and technology, released a statement that claims the Canadian governments commitment to supporting science. “Our government is investing in science and research that is leading to breakthroughs that are strengthening our economy and the quality of life of all Canadians.
“While the government is returning to a balanced budget, science, technology and innovation remain a strong priority with an added $1.1-billion investment over five years,” he said.
But Ian Rutherford, Canadian Meteorological and Oceanographic Society based in Ottawa points out that the protest is not just about a failure by the government to fund science. “There is an insidious campaign to muzzle scientists, to keep science out of the news, to… make science unimportant,” he says. “I think it is wrong. The scientific community has to stand up and say this is nuts.”
One environmental scientist, Kringen Henein of Carlton University in Ottawa, told Nature: “I’m really depressed… I just became a grandmother…and what is my grandson’s country going to be like in forty years if this is the way we are going?”
UPDATE: An earlier version of this blog stated that 5000 participated in the march, according to an organizer’s count. The revised figure of 2000 is based on a police estimate.
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Scientists have shown that women who were first to settle in a new land had more children and grandchildren than those who followed.
Researchers analysed the family trees of French settlers who colonised Canada in the 17th and 18th centuries.
Their results could help to explain why some rare genetics diseases are common in communities established by migrations.
The findings have been published in the journal Science.
The team of researchers from Canada and Europe relied on data collected by the parish councils of Charlevoix and Saguenay Lac Saint-Jean, a region 170km north of Quebec, Canada.
The towns not only boast dairy farms, charming villages and sandy beaches but some of the best ever-kept marriage records – comprising more than a million people.
By building a picture of marriages and how many children the pairings produced, the researchers showed that woman who arrived as part of the first wave of immigration had 15% more children than those who arrived a generation later.
The pioneering woman married younger and benefited from scooping up the best local resources, they added.
But the study also found that the pioneering women’s children also had more children.
Lead author Laurent Excoffier, from the University of Bern in Switzerland, explained that the children of women at the front of the wave inherited their mother’s higher rate of fertility.
Yet, the researchers added, there was no such correlation between generations that arrived 30 years later behind the first wave.
Dr Excoffier drew parallels with cane toads. Scientists have observed that the toads at the edge of their range have bigger front legs and stronger back legs; all the better to invade new areas.
And when toads at the frontiers breed, their offspring inherit these longer, stronger limbs.
Such an effect is not unexpected, but until now no one has seen this phenomenon in humans.
“This was a rare chance to study a relatively recent human migration,” said co-author Damian Labuda, a geneticist from the University of Montreal, Canada.
Population geneticist Montgomery Slatkin from University of California, who was not involved in the work, called the study one of the “most interesting, detailed studies” he had seen.
“I think what happened [here] could easily have happened in other populations,” he added.
The findings suggest that families at the front of the wave of migration contributed more to the contemporary gene pool than those that were slower to arrive, explained Dr Labuda.
This could help explain why some rare genetic diseases are more common than expected in the Charlevoix and Saguenay Lac Saint-Jean regions.
That is because any disease causing mutations carried by people by the frontiers would be pass onto their descendents, who make up a large proportion of subsequent generations in the population.
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For mothers-to-be, doctors worldwide advise taking a folic acid supplement. That’s because pregnant women with a deficiency of this vitamin have an increased chance of giving birth to a baby with serious birth defects, such as spina bifida and anencephaly. Yet a new mouse study shows that folic acid supplementation can itself sometimes increase the risk of birth defects or even cause the death of embryos. Experts caution, however, that the unexpected rodent results are too preliminary to require an immediate change in medical practices until more is known about how the vitamin influences development.
People typically obtain folic acid, or folate, from consuming leafy vegetables, but not everyone gets enough from their diet, particularly pregnant women. The vitamin plays a key role in the development of the neural tube, the embryonic region that gives rise to the spinal cord and brain.
Evidence from randomized clinical trials has shown that babies born to women who double their recommended daily dose of folic acid are between 40% and 50% less likely to have birth defects of the spine, skull, and brain. As a result, the United States has fortified most of its grains with this vitamin since 1998, and a handful of other countries have followed suit.
To the surprise of the researchers, in three of the five strains, the extra folic acid seemed to worsen the severity of birth defects rather than remedy them. In one of the mutant lines, dubbed L3P, eating the higher folic acid diet long term increased the chance that young were born with neural tube defects from 20% to 60%, the group reports in the 15 September issue of Human Molecular Genetics. And for another strain, Shroom3, many of whose embryos don’t naturally survive until birth due to their genetic problems, eating the higher folic acid food significantly increased the percentage of lost embryos.
Niswander says it is clear that folic acid is good for human fetuses, but the new study makes her wonder whether high levels of the vitamin may be harmful in some circumstances. Still, she stresses that more data are needed before any serious reconsideration of how much folic acid to recommend for impending mothers.
Roy Pitkin, a retired University of California, Los Angeles, researcher who specialized in pregnant women’s nutrition and chaired an Institute of Medicine panel that in 2000 reviewed folic acid’s health effects also cautions against a rush to judgment: “It would really be throwing the baby out with the bath water to say that because of this one mouse study, we are going to question the food fortification.”
Especially, he says, because we know that species differ considerably from each other when it comes to birth defects. He offers the example of thalidomide—a drug given to pregnant women in the 1950s to cure morning sickness—that causes severe human birth defects but that is perfectly safe in rats.
Neuroscientist Elizabeth Grove of the University of Chicago studies how the mammalian brain develops and echoes this concern. She warns that researchers have found hundreds of mutations that cause birth defects in mice but that so far don’t seem to produce the same problems in humans. The effects of folic acid may also be species specific, she says.
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Single babies born to mothers of twins tend to be heavier, report scientists.
The report in the journal Biology Letters is based on a 40-year data set collected in The Gambia.
Mothers with twins were found to give birth to heavier babies, but the study found a similar trend even among single babies born before twins.
Twin pregnancies are risky for both mothers and offspring, and the study suggests heavier, healthier single children may offset those risks.
Worldwide only 13 in 1,000 babies are born a twin, although this rate is higher in developing countries.
Researchers interested in probing the twinning question further have had to rely on the few long-term data sets collected in parts of the world where birth rates are higher, and there are therefore more twinning events.
Evolutionary biologist Ian Rickard from the University of Sheffield in the UK, saw an opportunity to do just this when he learned of a long-term data set from The Gambia, which included not only birth weights of about 1,900 babies born to around 700 mothers, but also the number of twins.
Analysing all 40 years, Dr Rickard explained that he and his Gambian and London-based colleagues saw that women who produced twins gave birth to heavier non-twin babies.
The exact differences, however, depended on when those single babies were born.
The Gambia experiences regular variations in food supply, from a “harvest season” between January and June, and a “hungry season” for the rest of the year.
Single babies born during the harvest season before twins were on average 226g heavier than those from non-twinned families; those born after the twins were 134g heavier.
However, single children born into twinned families in the hungry season showed no discernible difference in average weight from those of non-twinned families.
“We’ve known for quite a while that… if a [foetus] is exposed to a period of the year between about July and October during their third trimester, they tend to have lower birth weight,” said Dr Rickard.
The assumption is that the stress of food scarcity swamps the heavier-baby effect found in the harvest season.
Producing twins, Dr Rickard suggested, could be just a by-product of natural selection acting on birth weight.
However, he stressed the “importance of replicating this [finding] in another population to see if this pattern holds up”.
He suspects that a hormone called IGF, which has long been linked to birth weight in humans, could be responsible for this pattern.
IGF is known to influence the growth rate of foetuses, and is implicated in the “polyovulation” that leads to multiple births.
In cattle, IGF levels tend to be 1.5 times higher in the cows who give birth to twins, and in mice high levels of the hormone are linked to larger litters.
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Don’t be duped by its delicate pale flowers; Japanese knotweed can be a sinister plant. Native to eastern Asia, Fallopia japonica was intentionally introduced into gardens in Europe 200 years ago by fans of its attractive blooms; from there it spread to North America. What makes this invasive weed so menacing is its ability to grow through solid concrete foundations, forcing contractors to abandon infested building sites. In England alone, about a half-million homes are uninsurable, and in the United Kingdom, damages and removal cost $288 million a year.
Now the British government has taken a bold step to solve this knotty problem, and North American researchers might not be far behind. Last week, after more than 5 years of research into the matter and an initial pilot trial, the United Kingdom approved the widespread release of one of the plant’s natural enemies. While there are dozens of biological controls already in use against insect pests, this is the fi rst offi cially sanctioned release of one against a weed in the European Union. “This is an extremely important step. … If this is successful, it will really open the doors and open the minds of people for this control method in Europe,” says weed biocontrol specialist Hariet Hinz of CABI Europe in Delemont, Switzerland, a nonprofi t agricultural research organization.
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