Icict promove I Fórum Nacional de Informação em Saúde, 26 e 27/10

Entre os dias 26 e 27/10, o Instituto de Comunicação e Informação Científica e Tecnológica em Saúde (Icict/Fiocruz) promove o I Fórum Nacional de Informação em Saúde: pesquisas, realizações e perspectivas. A iniciativa, que é parte da programação do XI Enancib, visa discutir e elaborar projetos na área de informação em saúde para seu fortalecimento e construção de novos saberes. O evento acontecerá na Escola de Biblioteconomia da Universidade Federal do Estado do Rio de Janeiro (Unirio), na Urca. Para mais informações: 21 3865-3245. Confira a programação completa do Fórum. Participe!

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Dad's Diet May Give Children Diabetes

A pregnant mom who regularly chows down on cheeseburgers probably isn't doing her baby any good; she may even predispose him to obesity, according to some studies. But when pediatrician Sheau-Fang Ng noticed that her chubby child patients tended to have not just one but two overweight parents, she began to wonder: Could dad's habits be weighing in, too? She and her colleagues have now found the first direct evidence that a father's diet, not just his genes, can increase his offspring's risk of diabetes and other diseases, at least in rats.

Dangerous dad. Fat male rats may
pass diabetes down to their offspring.

In a simple experiment, the researchers—based at the University of New South Wales in Sydney, Australia—fed normal male rats a diet consisting of more than 40% fat, the rodent equivalent of vending machine food. The animals quickly became obese. The rats' daughters, born from mothers of normal weight and fed a healthy diet, weren't fat, but they did show early signs of diabetes by the time they reached puberty. Not only did their insulin levels fail to rise in response to high glucose, the team reports online today in Nature, but their insulin-producing islet cells in the pancreas also expressed very different genes than do normal islet cells.

In addition, many of the daughters were underweight at birth, which, in humans, often foretells obesity later in life. Sons of fat fathers showed some signs of diabetes, too, but to a much lesser extent than their sisters. Lead author Margaret Morris believes that the sons, too, would likely develop symptoms as they age or if they were fed a high-fat diet.

The effect is "much more subtle than what studies have observed in the offspring of mothers who eat high-fat diets," says Morris. Whereas a mother's diet and hormones affect the fetus throughout pregnancy, a father's contribution is limited to conception, leading the researchers to conclude that the high-fat diet had somehow altered the male rats' sperm.

The prime suspect, says Morris, is not a genetic mutation in the sperm's DNA, but an "epigenetic" alteration in chemical tags on the DNA. These epigenetic tags help determine whether a gene is expressed, and they can be passed on to offspring. During sperm development, which is occurring constantly in the male, epigenetic marks are erased and replaced. Environmental factors such as diet may interfere with this process.

"What that means for society is that males need to be conscious of the fact that their nutrition could have impacts on their offspring before they're even conceived," says epigeneticist Michael Skinner of Washington State University, Pullman, who was not involved with the research. Men might also be wary of smoking and pesticide exposure, the harmful effects of which could also be passed down to children epigenetically, he says. "When the vast majority of disease has no correlation to any identifiable genetic abnormality, we have to stop thinking that everything is genetic."

Morris agrees. Genes alone don't explain why younger and younger people have become diabetic and obese over the past decades, she says. "Obviously, we need to do more work, but if the same phenomenon is relevant in humans, it may explain some of the recent demographic shift toward early diabetes."

Kelp Raft Carries Marine Stowaways Hundreds of Kilometers

You're not from around here, are you? That's what marine biologist Ceridwen Fraser thought when she spotted a piece of seaweed encrusted with large barnacles on a New Zealand beach in 2009. Turns out she was right. Genetic data now reveal that the kelp came from islands hundreds of kilometers to the south. And it carried hitchhikers—at least 10 types of marine invertebrates. The find represents the first direct evidence that whole communities of organisms can make long ocean voyages floating on organic rafts.

Seafaring seaweed. This bull kelp carried tiny crustaceans 
and other invertebrates 400 kilometers before landing 
on a beach in New Zealand.

For more than a century, scientists have pondered how plants and animals colonize remote islands and hop between landmasses. (How did lemurs get to Madagascar, for example?) Charles Darwin suggested that floating vegetation could carry seeds long distances over the water. But direct evidence has been hard to come by. Scientists have observed brittle stars, anemones, and crustaceans riding rafts of seaweed in the open ocean, but few have witnessed them making landfall. Even less evidence exists for vertebrates riding rafts. A notable exception occurred in 1995, when a hurricane swept 15 iguanas off a Caribbean island. They traveled more than 300 kilometers on a tangled mass of trees before landing on a different island.

Jonathan Waters, a biologist at the University of Otago in New Zealand, suspected that a type of seaweed called bull kelp might be able to transport marine organisms like the trees had carried the iguanas. Kelp anchors itself to the seafloor with a hollow, rootlike structure called a holdfast that houses a diversity of marine organisms, such as worms, sponges, and crabs. When the kelp breaks off and floats away, presumably the organisms go with it.

Last year, when Fraser, a postdoctoral researcher working with Waters, spotted that kelp on the beach, she noticed that it carried some rather large goose barnacles. These crustaceans begin growing on seaweed after it begins to float. Because the barnacles grow at a known rate, scientists can use them to estimate how long the kelp has been at sea. More time floating likely means a longer journey. Most kelp Fraser sees on the beach has tiny barnacles or none at all. So finding a piece with larger barnacles was "really exciting," she says. By May 2010, the researchers had located five more kelp specimens with large barnacles. The team estimated that these kelp rafts had been at sea a minimum of 22 to 67 days.

To determine the kelp's origin, the researchers sequenced two of its genes. The new specimens genetically matched kelp from two island groups—the Snare Islands and the Auckland Islands, 390 and 600 kilometers distant from St. Clair beach on New Zealand's South Island, respectively. Given wind patterns and ocean currents, the kelp could have easily made the journey in the time it was estimated to have been at sea, the researchers will report online tomorrow in the Proceedings of the Royal Society B.

When the researchers dissected the holdfasts, they found a tiny teeming ecosystem that included 10 species of marine invertebrates: two tiny crustaceans, a sea spider, six species of mollusks, and a sea star. A genetic analysis of several of the crustacean hitchhikers revealed that they also came from Auckland Island, confirming the kelp results.

This is the first study to use genetic analysis to pinpoint the source of a raft carrying live organisms, says Kenneth Sytsma, a botanist at the University of Wisconsin, Madison. He says it will pave the way for more studies that look at the genetics of not only rafts but also seeds or spider eggs.

What the paper doesn't do is demonstrate that the organisms found inside the kelp could establish themselves in New Zealand, says Ellen Censky, a biologist at the Milwaukee Public Museum in Wisconsin and one of the researchers who reported the iguana landing.

Still, says Anne Yoder, an evolutionary biologist at Duke University in Durham, North Carolina, "it is another piece of evidence in the growing pile" that suggests rafting plays an important role in animal dispersal. She adds that much of the evidence in support of rafting has been circumstantial. This study, however, provides a clear demonstration that a single raft can carry several unrelated organisms across long distances, she says. "I definitely buy it."