MISCARRIAGE and pre-term birth are the two things all parents-to-be worry about. Two studies published this week could help establish why some pregnancies go wrong, and offer hope for new treatments to prevent pregnancies ending this way.

One in five pregnancies end in miscarriage, and the risk increases with the age of the mother. and colleagues at Washington State University in Pullman have now identified a surprising contributing factor: a lack of quality control during egg-making.

Hunt’s team found that not all of the immature egg cells, or oocytes, produced by mice contain the correct number of chromosomes. Egg or sperm cells divide through a process called meiosis, rather than the mitosis that is typical of cell division elsewhere in the body. There are several checks in place to make sure that meiosis occurs correctly, but Hunt’s team found that this process isn’t as strictly controlled in eggs as it is in sperm.

Specifically, when the pairs of chromosomes line up at what is called the meiotic spindle at the centre of the parent cell, they should await a chemical signal called the spindle assembly checkpoint (SAC) before dividing into daughter cells. However, the team found that eggs bend this rule. When they observed eggs dividing in ovaries removed from mice, they noticed that the SAC trigger for cell division waits for most – but not all – of the chromosomes to be lined up correctly. The consequence is either too many or too few chromosomes in the resulting egg cells, which can lead to birth defects or miscarriage (Current Biology, ).

The cell division process “is highly conserved between mice and humans”, says Hunt, suggesting that the same lack of quality control also applies to us. She reckons that we may be evolutionarily programmed to allow defective cells to divide because eggs are precious. “It is better to try and fail than to simply give up on an egg before it is even fertilised,” she says.

As the absence of a control mechanism can only increase the risk of chromosomal abnormality, So Iha Nagaoka, co-author of the study, says that IVF could be adapted to include screening that sorts the bad eggs from the good in a way that the body does not, helping to reduce the risk of miscarriage.

Premature birth is also a distressing experience for parents, and it is this aspect of pregnancy that at Washington University School of Medicine in St Louis, Missouri, concentrates on. Some 12 per cent of babies are premature, and caring for them costs the UK ÂŁ1 billion ($1.64 billion) a year.

Fay and colleagues think they have identified a contributing factor. “Humans have a shorter gestation period relative to their brain and body size than you would expect looking at other primate lineages,” he says. This is a result of our large brains and the narrow female pelvis, which mean that in order to maximise the chance of both mother and baby surviving, our gestation period has had to shorten.

The researchers think that this shortening is encoded in the genes involved in birth timing, some of which must have evolved rapidly since we diverged from other apes, to keep up with the growth of our brains.

To find out, the team compared numerous genomes from humans and other primates and pinpointed around 150 likely candidates for genes involved in accelerated birth timing. When the researchers looked for these genes in 328 mothers in Finland they found that variations in a gene called FSHR were more frequent in mothers who gave birth before 37 weeks of gestation. The team says the gene could be a new target for therapeutic measures to prevent pre-term births (PLoS Genetics, ).

“It was surprising to find that FSHR was involved,” says Fay. The hormone it controls- follicle stimulating hormone (FSH)- has a well-known function in the establishment of pregnancy rather than the initiation of labour. “It suggests that we should start looking at risk factors for pre-term births much earlier than 25 to 35 weeks into gestation,” he says.

“We should start looking at risk factors for pre-term births earlier than 25 to 35 weeks into gestation”

at Harvard University says that it may be significant that the neighbouring gene to FSHR – called LHCGR – is responsible for producing a hormone that helps to maintain a thick uterus during pregnancy. Any variations to FSHR might have a knock-on effect on nearby genes, he suggests.

The process of human birth is unique among primates because the infant emerges with its head facing in the opposite direction from its mother, or so the argument goes. Now, the first close-up videos of three chimpanzee births suggest that theory is wrong. In all three cases, the newborn emerged with its head facing away from the mother (Biology Letters, ).

It has also been suggested that the orientation of human newborns accounts for another uniquely human aspect of birth- the need for a midwife. Indeed, midwives contacted by żěè¶ĚĘÓƵ say that the differences in birth-related mortality rates between countries with good and poor levels of medical care shows the difference their assistance makes.

But this idea may also now be up for revision. at the Great Ape Research Institute of Hayashibara Biochemical Laboratories in Okayama, Japan, who led the study, says that chimps make nests so that they have a safe place to give birth, which could allow this style of birth to occur without assistance.

Here’s another reason to eat your greens. As well as helping to prevent cancer, broccoli may also help the immune system to clean harmful bacteria from the lungs. A compound found in the vegetable is now being trialled as a treatment for people with lung disease.

To ensure that the lungs function correctly, white blood cells called macrophages remove debris and bacteria that can build up in the lungs and cause infection.

This cleaning system is defective in smokers and people with chronic obstructive pulmonary disease (COPD) – a combination of emphysema and bronchitis – who suffer from frequent infections.

Now, researchers have figured out that a chemical pathway in the lungs called NRF2, involved in macrophage activation, is wiped out by smoking. They also found that sulphoraphane, a plant chemical that is made by broccoli, cauliflower and other cruciferous vegetables when damaged, such as when chewed, can restore this pathway.

Service restored

at Johns Hopkins University in Baltimore, Maryland, and colleagues, exposed defective macrophages from the lungs of 43 people with COPD to two bacterial strains that are common causes of COPD-associated infections.

In the presence of sulphoraphane, the NRF2 pathway was boosted and the macrophages’ ability to recognise and engulf bacteria was restored.

The researchers then exposed mice to smoke for one week or six months. Both groups were found to have increased bacterial colonisation of the lungs, similar to that seen in COPD. After treating the mice with sulphoraphane, they found that bacterial clearance increased. Rather than activate more macrophages, sulphoraphane appeared to improve the functionality of the cells already present.

Good greens

Sulphoraphane is present in broccoli in its precursor form and is converted to the active compound by enzymes present in saliva and intestinal bacteria, says Christopher Harvey, co-author of the research.

The levels of enzyme vary between people, and it would therefore be expected that the dose of sulphoraphane obtained by dietary consumption would vary between people too. Further human studies are required to establish beneficial effects of a sulforaphane-rich diet on immune defenses, he says.

Biswal’s team has started phase 2 clinical trials to test the compound in people with COPD to see if it improves their lung function, but says it will be three years before they have results. “There are many diseases that have defective lung function as a result of increased bacterial function in the lungs,” he says, “so this study can be extrapolated to those diseases too.”

Journal reference: Science Translational Medicine, DOI: 10.1126/scitranslmed.3002042

JUNE marks 30 years since the first report of AIDS – a syndrome that has killed an estimated 25 million people worldwide. Yet this year’s anniversary is somewhat arbitrary: the virus responsible for AIDS has probably been circulating within human populations for 100 years. Why did it take so long to detect it?

In June 1981, doctors reported an in five previously healthy young homosexual men in Los Angeles. Two years later the cause of their immunodeficiency was identified: a retrovirus that targets white blood cells, subsequently named human immunodeficiency virus (HIV).

Similarities with the simian immunodeficiency virus (SIV) that infects chimpanzees in west-central Africa suggest the original source of the infection, which probably spread to people who hunted and ate the apes.

Thanks to two chance finds in medical samples collected 50 years ago in what is now the Democratic Republic of the Congo (DRC), we even know roughly when HIV arrived. In 1998, researchers found HIV in a blood sample collected in 1959. This was followed in 2008 by a second discovery of the virus in a sample collected from a woman’s lymph node in 1960. The two viruses were subtly different due to their independent evolutionary histories. Comparing their gene sequences established that they likely diverged from a single common ancestor between 1902 and 1921, suggesting HIV has been in human populations for at least that long. Gene sequences also reveal that HIV spread from Africa to Haiti – probably shortly after what is now the DRC gained independence from Belgium in 1960 – and arrived in the US around 1969.

For at the University of Edinburgh, UK, it is obvious why HIV went undetected for 70 years. If infection follows an exponential curve, he says, there may have been just 4000 cases in west-central Africa in 1960. The researchers who found the two samples can count themselves “very lucky” to have done so, he says.

at the University of Arizona in Tucson is one of those researchers. “Finding those specimens did involve luck – but also time, energy and perseverance,” he says. He thinks HIV evaded detection for other reasons. There is a delay of about 10 years between infection and onset of symptoms. And AIDS isn’t associated with a specific suite of symptoms. “HIV causes you to die from any number of other infections.” In an area like sub-Saharan Africa, where a number of fatal diseases are already rife, it is only with hindsight that some of those deaths can be attributed to HIV.

Worobey says that what is truly telling is not that HIV circulated unnoticed in Africa for 70 years, but that it went undetected in the US between 1969 and 1981. With an exponential rate of spread, there may have been about 100,000 infections by the time the first cases were reported in 1981. “It took 12 years and 100,000 cases in a developed country to detect HIV, so it’s not a mystery that it remained hidden for so long in sub-Saharan Africa,” he says.

“The past 30 years really is just the tip of the iceberg in the history of HIV.”

The children – aged between 8 and 17 – had been blind since birth but had then undergone surgery to restore their sight. Within 48 hours of the operation, and colleagues at the Massachusetts Institute of Technology asked the children to feel a toy block without looking at it.

They were then presented with two similar but distinctive looking blocks – one of which was the block they had just touched – and asked to identify it from its appearance alone.

Their average success rate was just 58 per cent – barely better than chance – suggesting that mapping touch to sight must be learned. (Other tests showed conclusively that the two blocks used were easily distinguishable both by sight alone and by feel alone.)

Natural improvement

However, with no further training the children improved their performance significantly in just five days. “Experience with the natural world was most likely responsible for the improvement,” says Held.

But why is there a lack of hard-wired direct mapping between the two senses? “As a child grows, their sensory apparatus undergoes physical changes, as do the internal representations of the external world. In the face of such variability, a learnable mapping between modalities would offer significant advantages over a hard-wired one,” Held suggests.

at the Max Planck Institute for Biological Cybernetics in Tübingen, Germany, is impressed by the speed with which the children’s performance improved. “The fact that this learning needs so little time suggests that the necessary hardware and wiring was already in place in these children before the operation” despite never having been used, she says.

In 1688, when Molyneux first pondered this problem, it was just a thought experiment. It has proved difficult to investigate even since the advent of surgery to reverse some forms of blindness, because sight restoration operations typically occur in children who are too young to offer unambiguous answers.

Journal reference:

Species: Mastacembelus apectoralis

Habitat: Lake Tanganyika in east Africa, between a rock and a hard place

One species of spiny eel really knows how to travel light. It doesn’t bother with pigmentation or patterning, giving it a creamy pale complexion. Unlike most bony fish it’s shed most of its scales. And it even makes do with a less-than-complete complement of fins to get around.

The development of fins was one of the because of the greater mobility that they allowed. The pectoral fins, sitting just behind the gills, are particularly important for manoeuvrability, and they also play a key role in balance and braking.

Other fish have found imaginative new uses for these two fins. California flying fish () have developed huge pectoral fins that help them glide through the air. The red gurnard () has turned its pectorals into flexible spiny “legs” that act as sensitive chemical sensors. And those of the mudskipper () are different again: they have become a crude but stout pair of limbs that allow the fish to crawl about on land, perhaps like the first limbs of our distant ancestors.

Useful and versatile they might be, but for Mastacembelus apectoralis, the pectoral fins seem to have got in the way. This freshwater eel, just been described for the first time by a , has completely lost them.

Shrivelled pecs

It might seem like a dramatic loss, but the apectoral eel isn’t going it alone. Its near relative, , has tiny vestigial pectoral fins, which are probably about as useful as the puny arms of Tyrannosaurus rex were.

Both fish live in Lake Tanganyika, a body of water so large it is shared between four countries – Burundi, the Democratic Republic of the Congo, Tanzania and Zambia. Another dozen closely related species of eel are found in the lake, but only in these two are the pectoral fins shrivelled or missing altogether.

Why get rid of such versatile appendages? Because even the most apparently useful innovations can become cumbersome in the wrong circumstances. Both the apectoral eel and the eel with tiny pectorals live their lives on the rocks. Small or absent pectorals might allow these fish to squeeze into the tiny nooks and crannies between the boulders on the lake bed – a bonus if this provides a way to dodge predators or to find tasty morsels that might be lodged in the cracks. Not all fish living here show such an extreme adaptation, so it might be that the apectoral eel is burrowing deeper than the others.

In total there are 15 closely related species of freshwater eels in Lake Tanganyika, each with its own distinct lifestyle – and their common ancestor probably arrived there at least 7 million years ago, when . But this nice example of adaptive radiation – a single ancestor giving rise to an array of species all exploiting slightly different environmental niches – has been largely overlooked by biologists before now.

The reason? Paradoxically, because Lake Tanganyika is already considered the – only not because of its eels. There are over 250 species of cichlid in the lake: their presence seems to have blinded biologists to other examples of evolution in action occurring there.

Journal reference:

Read previous Zoologger columns: The only primate that eats its dinner twice, Biofuel powers biggest flying marsupial, Cryo-frog survives deep freeze, Megamouth, the shark that has to suck it up, The hairy beast with seven fuzzy sexes, Australia’s truly glamorous camper, Jet-propelled living fossil with a problem, The sharpest mind in the farmyard, Invasion of the crazy incestuous ants, The fish with no stomach for its prey, Well-fed black widows promise safe sex.