Every 9.5 minutes, another person in the US is infected with HIV (pictured). Today, the Obama administration announced a plan to reduce that number by 25% in 5 years — or about one person every 12 minutes — a goal officials say is as aggressive as it is realistic.

Some progress in reducing the rate of infection has made Americans complacent, said Health and Human Services Secretary Kathleen Sebelius in the blue-curtained South Court Auditorium of the White House. “We’re keeping pace when we should be gaining ground.” Some 1.1 million Americans live with HIV and there are 56,000 new infections annually.

The plan aims to reduce some of the disparities in treatment between rich and poor, and to more quickly connect newly diagnosed patients to clinical care. The administration wants to boost the proportion of patients who are receiving care within three months of their diagnosis to 85%, up from 65%.

How will they do all this, with little in the way of new money to spend? Like the plan implemented during the Bush-era steps, the AP reports, the Obama administration says it will make money go further, with inter-agency coordination that prevents wasted, duplicated efforts.

The optimistic policy could be coming at a good time. Last week, scientists reported the discovery of two human antibodies that could be used to design vaccines. And this morning, a report from UNAIDS, a United Nations programme on HIV/AIDS, said new infections among young people in the 15 most affected countries are dropping significantly as they embrace safer sexual behaviours.

Bill Gates, who spends much of his foundation’s money on HIV and AIDS work, was also pushing the agenda. In a preview of a speech on HIV prevention that he’ll give at the International AIDS Conference in Vienna next week, Gates told reporters today, “I hope AIDS stays in the headlines.”

Image: C. Goldsmith/Wikipedia

The first study to sequence the chicken Z chromosome revealed surprising facts about its mirror image in humans – the X chromosome.

For a century, scientists have assumed that the mammalian X sex chromosome has evolved very little in comparison to the Y chromosome. But a study in Nature today shows that the X chromosome evolved dramatically and in parallel to the chicken’s Z.

In mammals, females have a matching pair of sex chromosomes (XX) while males carry two different ones (XY). In chickens the situation is reversed: males have a matched pair of Z chromosomes and females have a ZW set. Scientists have long thought that most evolutionary change occurred in the chromosome found in only one of the sexes, the W and the Y.

“The X has been viewed as the unchanging foil against which we measure change in the Y,” says author David Page from the Whitehead Institute in Cambridge, Massachusetts.

Before ancient birds and mammals parted company around 300 million years ago, “when we were reptiles of some sort”, Page says, “we had no sex chromosomes”. Both the X and Y and the Z and W evolved from two separate pairs of identical non-sex chromosomes – or autosomes.

Now, after sequencing the chicken Z chromosome, Page’s team found some similarities with its mirror image, the X chromosome.

The Z chromosome has the lowest gene density of any chicken chromosome – less than half the average of that found on non-sex chromosomes. The researchers also found a large number of genes on the Z chromosome that were amplified and expressed predominantly in the testis.

These features reminded the team of the X chromosome – which also has relatively few genes along its length and contains a number of amplified genes expressed in the testis. This latter similarity was surprising because it seems to say that the evolutionary forces at work in sperm production seem to be trumping the differences between bird and mammal sex chromosomes, Page says.

“We hadn’t been looking for a parallel,” Page says, “but now there are two independent experiments of nature yielding the same outcome.” In both the mammalian and avian lineages, different portions of the ancestral genome were remodelled substantially to become specialized sex chromosomes.

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Bees may seem a surprising choice as a monitoring tool. But their sensitivity to chemicals has made some scientists big fans.

The buzzing, pollen-loving insects have been utilised for potential bomb detectors at airport, landmine seekers, and pollution monitors.

Using living organisms to test environmental health is known as bio-monitoring, and it dates back to the classic canary-in-a-coal-mine trick. Now the New York Times has a nice story on how the Düsseldorf International Airport and seven other airports are using bees to monitor air quality.

If plants have been exposed to toxins, that would show up in the nectar and any subsequent honey from bees that visit the flowers. By keeping hives near an airport, you should have a natural accumulator of any pollutants.

The first batch of this year’s honey harvest from some 200,000 airport bees was tested in early June, and indicated that substances such as certain hydrocarbons and heavy metals were far below official limits.

Local bee-keepers keep the bees, bottling up the honey – Düsseldorf Natural – which was comparable to honey produced in areas without any industrial activity and can be gifted, reports the Times.

Image: photo by MB Jarrosak via Flickr under creative commons.

Creating hybrids by crossing closely related species of plants is common pratice in horticulture, but when it comes to chorus frogs such hybridizations can be maladapative, a new study shows.

At the ongoing Evolution 2010 meeting in Portland, Oregon, evolutionary biologist Emily Moriarty Lemmon from Florida State University in Tallahassee impressed her colleagues with the results of her chorus frog hybrid study. She and her husband/collaborator Alan Lemmon (collectively they are known as “the Lemmons”) estimated the fitness of hybrids of the chorus frogs Pseudacris feriarum and Pseudacris nigrita, who coexist in the southeastern US. They crossed these two species and raised the offspring in the lab until sexual maturity. The Lemmons studied the viability, mating success, and fertility across the life cycle of their hybrids and found their fitness was reduced by 44% compared to their parent species. The decline was the result of females selecting against hybrid males as well as natural selection on male fertility. In other words, fewer females wanted to mate with the male hybrids, and those that did often got poor results. Ultimately, says Lemmon, this drives the two closely related speices toward reproductive isolation. “Hybridization is costly,” she says.

Nearly 2,000 researchers coverged on the Evolution 2010 meeting this year where, unlike most professional gatherings, enthusiastic conversations about animal sex are quite all right.

Image: chorus frog / John White

A decade of vicious, internecine battles between chimps has been documented in a new paper in Current Biology.

Twenty-one chimps were killed or fatally wounded in Kibale National Park, Uganda, over this time period by a group of male chimps from a large community in a region of the park called Ngogo. As many as 13 of the victims may have belonged to a single neighbouring group, representing an extremely high rate of mortality due to intergroup violence, exceeding median rates of mortality due to intergroup violence reported for humans in agricultural and hunter-gatherer populations and compared to the median rate suffered by individuals in 9 well-studied chimp communities. The motive appears to be territory.

John Mitani from the University of Michigan in Ann Arbor and his colleagues spent 10 years observing the 150 Ngogo chimps. They even watched 18 of the killings (the other three were inferred from carcasses and faeces containing chimp remains).

Most of the time, male chimps behave like rowdy, loud frat boys, but once every 10 to 14 days, they act like cooperative adults and wage war. The New York Times reports:

A band of males, up to 20 or so, will assemble in single file and move to the edge of their territory. They fall into unusual silence as they penetrate deep into the area controlled by the neighbouring group. They tensely scan the treetops and startle at every noise… If a single chimp has wandered into their path, they will attack. Enemy males will be held down, then bitten and battered to death. Females are usually let go, but their babies will be eaten.

After the bloodshed, the Ngogo chimps usurp the area once occupied by their victims, literally enjoying the fruits (genus Morus) of their labour. “The take-home is clear and simple,” Mitani says (news release). “Chimpanzees kill each other. They kill their neighbours. Up until now, we have not known why. Our observations indicate that they do so to expand their territories at the expense of their victims.”

The Ngogo chimp patrols have expanded their 29-square-kilometre territory over the years, but during the summer of 2009, they nabbed a sizable 6.4-square-kilometre chunk to the northeast – increasing their land by 22%. With bountiful land and resources, the males grow stronger and their females – who likely increase in number – have more babies.

While the study has implications for the evolution of cooperation, the authors caution against extrapolating their study into the realm of human warfare. “Invariably, some will take this as evidence that the roots of aggression run very deep,” Mitani says (Time). But even if that were true, “we operate by a moral code chimps don’t have” he adds.

Image: NIH

Besides behavioural immaturity and experimental curiosity, the teenage years are also marked by brain development—making the rise of adolescent binge drinking particularly worrisome to neuroscientists.

Now, researchers show in PNAS today that alcohol decreases the levels of stem cells in the brain, which may lower its ability to repair damage. “The public expects adolescence to be an age when you try new things and you can fight out stuff,” says Chitra Mandyam from the Scripps Research Institute in La Jolla, California. “But when you’re still developing as an individual, if you change the capacity of the brain to maintain whatever it’s trying to maintain, you alter the balance of the brain as it grows.”

Mandyam’s team bartended for seven adolescent male rhesus monkeys, offering them Tang mixed with ethanol to a potency of 6% (that’s higher than your average American bar brew).

After establishing that all the test monkeys could be big drinkers, the researchers allowed only four of them to continue drinking the citrus flavoured cocktail once a day for 11 months. “Monkeys love to drink. They’re like humans,” Mandyam says. The legal blood alcohol level (BAL) limit for driving is 0.08. These four monkeys were intoxicated with BALs between 0.1 to 0.3. (That’s about 10 or 12 cans of beer.)

Then the researchers examined the brains of the monkeys that kept drinking two and a half months after making them quit cold turkey and found that they had an 80-90% reduction in the stem cells of a portion of their brain known as the hippocampus, compared with the monkeys kept sober.

The hippocampus is necessary for spatial learning, short and long term memory, and executive functioning. (It’s not solely responsible for those activities, but if you need to remember what exit to take when driving home, what your mom’s name is, or what two plus two equals, you need your hippocampus to work.) The hippocampus is also a place where the adult brain can generate new brain cells. The region produces stem cells that give rise to progenitor cells that mature into neurons, which then get incorporated into the existing hippocampal neural circuitry. This is called neurogenesis.

“These stem cells go through several milestones to become neurons,” says Mandyam, who looked upstream and found that alcohol reduces the stem cells and the progenitor cells that become new neurons. Previous researchers have shown that substance abuse decreases neurogenesis in the hippocampus, but how that happens has remained unknown. In this new study, the researchers found that the alcohol targeted the immature brain cells in adolescents, reducing the amount of new neurons born. “You’re messing with brain plasticity early on,” Mandyam says. “If you inhibit the cells so early in life, the chances of having normal production of cells later on in life is very unlikely.”

Even after a period of abstinence, the researchers still saw decreases in stem cells, progenitors, and neurons in the binge-drinking monkeys’ brains. The study suggests binge drinking during adolescent years might produce some of the memory deficits seen in adulthood due to decreases in adult neurogenesis.

“It’s very devastating to see what chronic binge drinking does to the adolescent brain,” Mandyam says.

Image: Stem cells highlighted in the monkey brain. Chitra D. Mandyam

The Alaotra Grebe (Tachybaptus rufolavatus) was a water-loving bird who lived in a tiny area in east Madagascar. It had small wings and fed on fish in its large, brackish lake home. It was declared extinct on Wednesday, 26 May

T. rufolavatus was described as a species in 1932 by French-American ornithologist Jean Théodore Delacour, and a pair was last seen 25 years ago in September. It fell permanent victim to introduced, chick-eating, carnivorous bass fish and nylon gill-nets used by fisherman in Lake Alaotra.

“No hope now remains for this species. It is another example of how human actions can have unforeseen consequences,” said Leon Bennun of BirdLife International, which compiles data for the International Union for Conservation of Nature (IUCN)’s Red List of threatened species. “Invasive alien species have caused extinctions around the globe and remain one of the major threats to birds and other biodiversity.”

In the latest Red List released Wednesday, the Zapata Rail (Cyanolimnas cerverai) of Cuba—named by ornithologist James Bond, Agent 007’s namesake—was driven onto the critically endangered list by nonnative mongooses and catfish.

In happier news… the Azores Bullfinch (Pyrrhula murina) of the island of São Miguel and the Yellow-eared Parrot (Ognorhynchus icterotis) of Colombia were both downlisted from critically endangered to endangered, as a result of conservation work to restore their habitats.

The Alaotra Grebe is preceded in extinction by 132 species of the 10,027 birds recognized by IUCN—and most recently by the 2008 extinction confirmation of the Liverpool Pigeon (Caloenas maculata). The Alaotra Grebe is survived (though just barely) by 190 critically endangered, 372 endangered, and 838 near-threatened birds.

Image by Chris Rose.

This summer, students at the University of California, Berkeley, will be asked to swab the inside of their cheeks and experience personalized medicine for themselves—but this gigantic and unprecedented experiment is not without its critics.

When I arrived at Cal in August 1999, I registered for classes over the telephone and the coolest thing in my welcome package was… completely forgettable. This year incoming freshmen and transfer students in the College of Letters and Science—which advises three-quarters of the university’s 25,000 undergrads—will notice a cotton swab in their welcome package.

The low-tech device is courtesy of the college’s “On the Same Page” program, which usually asks new students to read a new book or watch a film that would give them something to talk about for the rest of the year. This year’s topic is contemporary, interdisciplinary, and “will touch all our lives in some way”, says Alix Schwartz, director of undergrad academic planning (L&S News).

“Science is moving so fast right now,” Schwartz adds (Inside Higher Ed). “If we assigned them a book, it would be out-of-date by the time they read it.”

Students can choose to return a sample of their cells to be analyzed for three genes that help regulate the ability to absorb folic acid, tolerate lactose, and metabolize alcohol—all useful for the daily lives of college goers. Confidentially is maintained through the use of two barcode labels, one to affix on the sample and the other to keep and use to look up results once they’re posted on a website. Based on the results, students can take easy steps like eating more spinach or avoiding yoghurt. “The history of medical genetics has been the history of finding bad things,” says Jasper Rine, professor of genetics, genomics and development (NYT). “But in the future, I think nutritional genomics is probably going to be the sweet spot.”

The idea isn’t to identify dangerous genes, but to point out traits that can be managed through behaviour. “We want to get people to appreciate that there are things you can do that enhance your health based on the genes you have,” Rine says (Inside Higher Ed). “There are concrete, actionable, specific steps that do enhance quality of life. This is the message of the post-genomic era.” Students will also get the chance to enter poems, music, or other creations to compete for a more complete analysis by personal genomics company 23andMe.

This “genetic legacy” assignment has already proved to be controversial. The Center for Genetics and Society, a Berkeley-based public interest organization, is calling for a suspension of the project. The centre argues that direct-to-consumer genetic tests could exaggerate the importance of genes to behaviours that are shaped by social and environmental factors and that this kind of biotechnology should best be left to medical professionals.

“Just last week, the largest drugstore chain in the country halted plans to retail a similar product after receiving a stern letter from the US Food and Drug Administration,” says Jesse Reynolds with the centre (press release). “If selling genetic tests directly to consumers is a problem in the eyes of federal regulators, how can the university justify pushing them on thousands of eighteen-year-olds?”

Image: C-A-L-I-FOR–NIA, Janet Fang

A century ago, the Asian vine kudzu was introduced to the southeastern US where its deep roots were thought to be helpful for erosion control. Since then the invasive species has been swallowing landscapes and altering ecosystems, and now it appears that the horrible plant increases air pollution as well.

Like many other legumes, kudzu (Pueraria montana) develops symbiotic associations between its roots and bacteria in the soil. These bacteria transform atmospheric nitrogen into ammonium, a nutrient for the vine, and when that “fixed” nitrogen is released to the soil, it becomes available to other plants and microbes.

The fast-growing legume fixes atmospheric nitrogen at a really high rate and the resulting increases in nitrogen cycling has triggered a dramatic increase in nitric oxide emissions from soils, according to a new paper in PNAS. Nitric oxide is a key precursor to ozone, and while this usefully blocks the sun’s harmful rays when it’s high in the atmosphere, it is an air pollutant that damages lungs and prevents plants from absorbing carbon dioxide when it occurs at the surface.

“It turns out that the changes you can’t see in a kudzu invasion are just as dramatic as the ones you can,” says lead author Jonathan Hickman of the Earth Institute at Columbia University (news release).

This new study is the first to establish the link between a biological invasion and bad air quality. And kudzu currently commands three million hectares and is expanding its reach by about 50,000 hectares each year. “It’s an impressive and dramatic plant,” Hickman says (Discovery News).

Using a chemical transport model, the authors show that kudzu invasion can lead directly to an increase of high ozone days—up to 7 days each summer in some areas, or 35% increase compared to a scenario without kudzu.

“While documenting these impacts on soil chemistry and nitric oxide emissions is definitely important, we really wanted to see whether an invasive species could affect the atmosphere in a meaningful way,” says Hickman.

Kudzu is sometimes called the vine that ate the South. Hickman suggests a new appellation: ‘the vine that choked the South’.

Image by lowrevolution via Flickr

This week, scientists have announced not one, but two new nanorobots known as “DNA walkers” that could do what Ms. Frizzle and her elementary school class did on our television screens: they can move across the chemical blueprint of life.

In one of the studies (Lund et al.), the nanorobot—or “molecular spider”—acts autonomously by following cues on its pre-programmed course. It has 4 legs (but only walks on 3 of them) that are made of DNA enzymes. It navigates on a sheet of DNA origami designed to contain cleavable DNA strands that have base sequences complementary to the spider’s legs. After the legs form duplexes with complementary surface strands, they cleave one of these strands, which weakens the interaction of the spider with that strand. Then the spider forms a new duplex at another site farther down. By repeating these steps, the spider moves from one binding site to another along a path programmed into the DNA surface. The spider stops when it binds to uncleavable DNA strands at the end of the track. See News & Views: “Molecular robots on the move” (subscription required).

According to co-author Hao Yan from Arizona State University in Tempe, other DNA walkers have been developed in the past, but they have never ventured more than a few steps. “This one can walk up to about 100 nanometers,” he says (AFP). “That’s roughly 50 steps.” The next step is to make the spider walk faster, follow more commands, and make more decisions.

In another study (Gu et al.), a less autonomous (but more complex) DNA walker moves across the origami track with its 4 feet while picking up and carrying nanoparticle cargoes with its 3 arms. Instead of DNA enzymes, its feet are made of single-stranded DNA. Movement depends on single strands of DNA called anchor strands that join together other single strands on the walker’s feet and on the surface. When fuel strands are added to the system, they preferentially hybridize to these anchor strands, freeing up the walker’s feet. Binding and release is controlled by adding anchor or fuel strands. This nanorobot utilizes an assembly line operation, producing the target product by moving along the track and collecting gold nanoparticles as directed. See News & Views: “Molecular robots on the move” (subscription required).

Co-author Nadrian Seeman from New York University envisions these nano-sized machines functioning as microscopic factories, pumping out useful products in high yields (TechNewsDaily).

“This is the first time that systems of nanomachines, rather than individual devices, have been used to perform operations, constituting a crucial advance in the evolution of DNA nanotechnology,” writes News & Views author Lloyd Smith from the University of Wisconsin in Madison.

Image: The (green) spider traverses a substrate track built upon a DNA origami scaffold towards the (red) goal by cleaving the visited substrates. Paul Michelotti