Geriatric two-year-old mice with thinned, ageing skin treated by researchers temporarily reverted to having more youthful skin.

Researchers say that this approach – which involves switching off a key protein in the skin – differs from the use of Botox injections to reverse the appearance of skin ageing because it changes the skin cells themselves, rather than the muscles underneath.

However, the protein switched off in this new method also plays an important role in the immune response. For this reason, scientists caution that the technique might cause side-effects and is therefore unlikely to be used to erase wrinkles in people anytime soon.

at the Stanford University School of Medicine in California, US, and his colleagues began their research by studying blood samples taken from mice of various ages.

Pinpointing genes

Chang and his teammates used a technology called to get a picture of which ones of the 20,000 genes in the entire mouse genome are most active in the skin at different ages.

They found that a particular gene, called NF-Kappa-B, seems to exert a large influence by activating a number of genes in the skin – especially in old age.

Next, researchers designed a way to switch off the NF-Kappa-B protein produced by this gene.

The NF-Kappa-B protein normally turns on other genes by latching onto DNA strands inside the cell nucleus.

The researchers genetically engineered mice to carry another molecule that would travel to the cell nucleus and disable the NF-Kappa-B protein. But the molecule could only do this in the presence of a specific drug called 4-hydroxytamoxifen.

Thick skinned

Chang’s team applied skin patches containing the drug on the backs of 2-year-old mice – near the upper age limit of the rodent – and monitored what happened. They also applied a patch containing only ethanol as a control. The scientists refreshed the patches daily over two weeks.

The scientists observed no marked changes in the area of the skin under the control patch over this period. But the experimental treatment patch had produced about a 75% increase in the thickness of the skin.

Chang says this change is significant because, while mice do not get wrinkles as humans do, the rodents’ skin does become thin in old age – possibly as a result of the failure of new cell growth and the breakdown of supporting collagen proteins.

While the experimental mice showed no increased risk of disease, the researchers note that blocking NF-Kappa-B could have side-effects.

Wound treatment

The protein plays an important role in many biological processes, including the development of certain immune cells and immune system signalling. Theoretically, switching off the protein could make an animal more vulnerable to infection.

Alea Mills at the Cold Spring Harbor Laboratory in New York, US says that the new approach is “intriguing”, but cautions that turning back the biological clock inside skin cells might also increase the risk of skin cancer.

Chang’s team also notes that the effect of skin rejuvenation appears temporary in mice. However, they say the results from their mouse study might one day lead to the treatments to help wound healing in humans. “I think temporary relief is better than nothing,” says Chang.

Chang says he is less sure the new approach will soon produce a cosmetic treatment for wrinkles: “Whether this will turn into a cream or not, we don’t know.”

Journal reference: (DOI: 10.1101/gad.1588507)

“When biologists talk about the ‘battle of the sexes’ they often tacitly assume that the battle is between persistent males who always want to mate and females who don’t,” says Jakob Bro-Jørgensen at the Zoological Society of London, UK.

But previously, researchers had observed female gorillas interfering with copulating pairs to compete for the male. Now, Bro-Jørgensen has observed such behaviour among the African topi antelope (Damaliscus lunatus) in Kenya.

Competitive mating

Herds of African topi can number in the thousands. Typically females travel in large groups to mating hotspots – called leks – where about 10-20 males guard small territories, each measuring about 30 metres in diameter. Smaller males that fail to grab some of this prime real estate miss out on being able to participate in the intense mating, or lekking, that takes place.

Bro-Jørgensen, who has observed the African topi for a decade, analysed the mating habits of 98 females. They could be distinguished from one another by physical traits, such as natural markings on their horns, and scars on their ears.

The females are typically in oestrus for only one day a year. During that brief time they compete with other fertile females to mate with the fittest males as frequently as possible to ensure conception.

On average, the females mate with four males 11 times during this day. This is possible because the actual sexual act takes only a few seconds, says Bro-Jørgensen.

Disruptive females

He also observed that when a female saw a desirable male about to mate with another, she often charged at the couple with her horns. As a result, the male was sometimes forced to mate with the aggressor. But the researchers also noted that if the male had already mated with the aggressive female, he would fight her off.

The researchers suggest that the males get picky because they want to conserve their sperm and mate with as many females as possible, and thus maximise their chances of bearing offspring. Bro-Jørgensen says that he has seen a male topi antelope copulate 36 times in just one day, leaving the animal “totally exhausted”, and possibly with depleted sperm.

“For so long we have assumed that sperm is in unlimited supply,” comments Paul Verrell at Washington State University in Pullman, US. “That old dogma is falling by the wayside.”

Journal reference: (DOI: 10.1016/j.cub.2007.11.026)

The findings lend credence to traditional beliefs that eating certain foods can influence the sex of offspring.

The conventional wisdom is that the father’s sperm is the main determinant of the sex of a child. But increasingly scientists have found hints that maternal factors might have an influence too. For example, earlier work has suggested that single mothers are more likely to give birth to daughters.

at the University of Pretoria in South Africa and her colleagues wanted to study how changes in diet might influence sex ratios – the proportion of males to females in a population.

To do this, they altered the levels of blood-sugar in female mice during conception, by feeding the mice a steroid called dexamethasone (DEX), which inhibits the transport of glucose into the bloodstream.

Evolutionary advantage

The scientists gave 20 female mice water dosed with DEX for the first three days that the females were exposed to males. Afterwards, the mice were given plain water. Cameron’s team measured the blood-sugar levels of these mice, as well as that of 20 control females several times during the experiment.

The average blood-glucose levels in mice that received DEX dropped from 6.47 to 5.24 millimoles/litre. And the team found that 53% of the pups born to the control females mice were male, but only 41% of those born to the mice receiving DEX were male.

Exactly how a drop in blood sugar causes more female births remains unclear. But the opposite also seems to work. A previous study involving , found that rodents with high blood-sugar levels produced more male offspring than expected.

Biologists have theorised that mothers may give birth to more female offspring during times of stress or ill health, because it confers an evolutionary advantage. If the stressed mother gave birth to a weak male, he is unlikely to mate. But if the child was female, no matter how weak, she would likely bear more children.

Fitness marker

“It does seem that sugar levels could act as an indicator of whether a mother is in a good state or bad state,” says Ruth Mace at the University College London, UK. Mace previously published a study that found mothers with more muscle mass are more likely to give birth to sons during food shortages.

The idea of diet influencing sex ratio is already part of traditional wisdom. Folklore says that mothers should eat more red meat and salty snacks if they want a boy, and fish, vegetables, chocolates and sweets if they want a girl.

“This is interesting, since meat raises blood sugar for a sustained period of time, whereas sugar-based snacks raise blood sugar very high, but for a short amount of time, followed by a slump in blood glucose,” says Cameron.

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Ancient written texts from the Middle East may reveal that the use of biological weapons dates back more than 3300 years, according to a new review.

The historical documents hint that the – whose empire stretched from modern-day Turkey to northern Syria – sent diseased rams to their enemies to weaken them with tularemia, a devastating bacterial infection that remains a potential bioterror threat even today, says the review.

Experts caution that more evidence is needed to firmly establish that the Hittites intended to spread disease using the animals. But they add that if this proves true, it might represent the earliest known use of biological warfare.

Tularemia, also known as rabbit fever, can pass from animals such as rabbits and sheep to humans through various routes, most commonly through insects such as ticks that hop between species. The bacterium responsible for tularemia, Francisella tularensis, causes symptoms ranging from skin ulcers to respiratory failure.

Modern medication can stop the tularemia from becoming fatal. But without proper antibiotic treatment, about 15% of infected individuals die, says Siro Trevisanato, a former microbiologist who has delved into the ancient texts.

Hittite plague

Tularemia is rare in many countries today, but remains a problem in some countries including Bulgaria, says Trevisanato, now based in Oakville, Ontario, Canada.

He believes tularemia is to blame for a deadly epidemic dubbed the “Hittite plague” which raged through the Middle East in the 14th century BC. Around 1335 BC, letters to the Egyptian king Akhenaten reported a pestilence in Simyra, a city near what is now the border between Lebanon and Syria.

The texts describe a terrible illness causing disabilities and death. Most tellingly, they mention that, because of the plague, donkeys were banned from being used in caravans.

According to Trevisanato, this indicates that the people living in the city were hit by tularemia. The disease can infect donkeys and the insects that they carry, so preventing the use of donkeys for transport may have been an attempt to quell its spread.

Roaming rams

A decade later, the Hittites to the north attacked the weakened area around Simyra. “The Hittites were able to steal booty, including animals, and brought the animals home,” along with the tularemia the livestock harboured, Trevisanato explains. Not too long after, the Hittites themselves apparently began to suffer from an epidemic of tularemia.

History seems to have repeated itself a few years afterwards when another ancient people, the Arzawans from western Anatolia, saw the weakened Hittites to their east and decided to strike. “They thought, if we attack now, we can push the border back to where we want,” Trevisanato says.

But strangely, during this period of warfare between 1320 and 1318 BC, records indicate that rams mysteriously began appearing on roads in Arzawa.

The Arzawans took the sheep to their villages and used them for livestock breeding. Soon after, though, they began to suspect a link between the appearance of the animals and the terrible disease ravaging their communities.

“They started wondering ‘Why do these rams start showing up on the road?'” says Trevisanato. He believes that among the Hittites, “somebody must have had the bright idea” to send diseased rams over to their Arzawan enemies.

Ultimately, the Arzawans were so weakened that their attempt to conquer the Hittites failed.

Modern threat

Trevisanato’s theory is intriguing, says Jonathan Tucker, at the James Martin Center for Nonproliferation Studies in Washington, DC, US who studies the use of chemical and biological weapons.

He points out that there is no vaccine for tularemia and that experts consider it a “possible or likely biological warfare agent” in the present day.

Still, in order to consider the rams as a true biological weapon, evidence is needed to clearly prove that the Hittites understood the full ramifications of these animals towards their enemies, says Mark Wheelis, at the University of California, Davis.

“The intent would have to be not to just freak the enemy out, but to actually transmit disease,” he explains. Until such intent to spread disease is proven beyond a doubt, Wheelis says any theory is speculative.

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The study of over 5400 children found that 11-year-olds showed greater physical activity than their peers if their parents had a history of hitting the gym at least twice a week.

“This is the largest study of its type that has used an objective measure of activity” to assess the impact of parents’ habits on their children’s inclination to exercise, says Calum Mattocks at the , UK, one of the team.

Mattocks and his colleagues reviewed data collected as part of the , which began following children in 1991. At the start, researchers gave parents questionnaires that asked, among other things, how often they exercised.

Learning from example

Then, a few years ago, scientists asked the children – aged 11 to 12 years old – to wear devices known as accelerometers for as much time as possible over a seven-day period. Accelerometers can keep a running tab of how frequently and intensely a person moves.

Recordings from the accelerometers indicated that the children who engaged in the least amount of activity burned a minimum of 1500 calories on average over per day, compared with their most active counterparts who used up about 2700 calories during the same period.

The scientists then looked back on the data collected when the youngsters were toddlers. They found that the children whose parents exercised at least twice a week grew up to be slightly more active – engaging in 5% more physical activity – than those youngsters whose parents never exercised.

Mattocks notes that other factors – such as physical education programmes in school – might exert a larger influence on how much adolescents exercise. Still, he believes that children do learn from example. For this reason, Mattocks and his fellow researchers believe that helping parents to increase their own physical activity could influence children to exercise more and thereby avoid obesity.

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Video: Researchers from Yale University showed babies puppet shows involving helping and hindering blocks to see if the infants could judge character.

Babies are good judges of character long before they learn to speak, according to a new study. Infants as young as six months preferred characters which helped rather than hindered others in a simple puppet show.

Researchers say the findings reveal that humans begin making social evaluations far earlier than previously thought.

“This is the very first experiment in anywhere near this age that shows babies develop preferences for individuals based on their actions,” says at Yale University in New Haven, Connecticut, US, who led the study.

Wynn and her colleagues studied the reactions of infants to a sketch in which a brightly coloured wooden block with goggly eyes attempts to climb up a hill. Much like in a puppet show, the infant could not see the person behind a curtain who controlled the character’s movement with a wooden stick.

Understood intent

Along with the wooden character attempting to climb the hill in tiny increments, a helper block was also involved at the bottom of the slope, which pushed the main character up the track from time to time.

Additionally, another wooden block positioned at the top of the hill occasionally came down to hinder the upward movement of the first block.

The blocks had different shapes and colours to help the babies distinguish one piece from another. But the scientists controlled for these attributes by varying them from trial to trial.

After the show, the researchers brought out the helper block and the hinderer block on a platter and placed it in front of the infants. A colleague who did not see the skit, and did not know the role of each block in the performance, recorded how the babies interacted with the objects.

Wynn says that the infants are very willing to reach out for one of the blocks, an action that indicated their preference: “They’re very cooperative in grabbing things.” She says that all 12 of the six-month-olds preferred the helper block. Similarly, 14 out of the 16 infants aged 10 months reached for the helper block.

The researchers believe that the babies understand the intent of the middle block to climb the mountain because of its small incremental movements in that direction. Wynn adds, though, that it is not clear how the babies pick up on this. “We don’t know exactly which micro-cues the babies pick up on,” she explains.

Early preference

Her team conducted a control experiment in which the main character – a small ball – was pushed up and down by the helper and hinderer blocks, but did not move independently. In this case the babies showed no preference for the helpful character that provided an uphill push.

Wynn notes that earlier studies have shown that babies have shown a preference for beautiful faces.

She believes the results from her study indicate that babies have a preference for helpful individuals about a year earlier than previously thought. “They are an unbiased third party and they are not at all shy about rendering a judgement on social actions,” she says, adding that this tendency appears early in development because it is a strongly advantageous trait later in life.

, a child development expert at York University in Toronto, Canada, says the results of the study are “very interesting” but is not certain whether babies evaluate the actions of people the same way they judge the actions of wooden blocks.

She notes that infants interact differently with people compared with objects such as dolls: “The babies will always respond more to a person with smiles and vocalisations than to the doll.”

Legerstee hopes the experiment will be repeated using another skit involving human actors rather than wooden blocks. By altering the people who play the role of helpers and hinderers the scientists can control for confounding factors, such as babies preferences for attractive people.

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The fossilised remains of a giant claw that once belonged to a sea scorpion roughly 2.5 metres long have been found in Germany.

Researchers say the monstrous creature is the largest arthropod ever known – over 30 centimetres bigger than the previous largest specimen of the same species.

at the University of Bristol, UK, and colleagues examined the 46-centimetre-long claw, found in a quarry in western Germany, and believe it belonged to a sea scorpion species called Jaekelopterus rhenaniae that roamed the ocean floors some 390 million years ago.

Some palaeontologists believe that J. rhenaniae used its claws to reach out and grab passing animals, such as fish, to eat. “They were the top predators at the time,” says Paul Selden at the University of Kansas in Lawrence, Kansas, US.

Sturdy claws

The claws of these creatures remain long after the rest of their body has disintegrated. “The body segments are quite flimsy,” Braddy explains, but “the claws are sturdy, so they preserve better in the fossil record.” As a result, his team had to extrapolate the size of the sea scorpion that once owned the massive claw.

Experts typically extrapolate the size of sea scorpions based on measurements of the claw and body size of the few specimens that have survived intact. But Braddy suspects that this simple method might lead to an overestimate of body size.

According to such calculations, the claw his group found would have belonged to a sea scorpion measuring 2.6 metres long. Braddy prefers a more conservative estimate of just under 2.5 metres.

Size mystery

J. rhenaniae belongs to a category of animals known as arthropods, distinguished by traits such as a segmented body and an exoskeleton, which includes modern species such as spiders and horseshoe crabs.

Although long extinct, some palaeontologists believe J. rhenaniae gave rise to modern-day land scorpions. Others believe that it represents an evolutionary dead end.

Why the creature reached such huge proportions remains something of a mystery, however.

Elevated levels of oxygen in the atmosphere may have allowed some prehistoric animals to grow very large, but Braddy points out that oxygen levels during the period in question were not elevated much beyond current levels. A much more likely explanation, he says, is that the sea scorpions needed a competitive advantage over other animals, including other related arthropods.

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Memory aid

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