Abstracts

Rainforest insect species diverse and widespread

(Nature | 8.9.07)

An international team of scientists that includes George Weiblen, associate professor in the Department of Plant Biology, has learned that the same insect species and their food plants are broadly distributed across a vast lowland rainforest on the island of New Guinea. The finding challenges the dogma that tropical insect diversity changes dramatically from place to place. “Rainforest explorers have long pondered how the cornucopia of tropical biodiversity is distributed,” says Weiblen, lead principle investigator on the National Science Foundation grant that funded the bulk of the study. “Our study shows that insect species often occupy vast areas of tropical forest such that communities of species don’t change much from place to place.”

The group studied 500 insect species across 75,000 square kilometers of rainforest in Papua New Guinea. Although species diversity was extremely high, as expected in the tropics, communities of insect species did not change much from place to place, even over hundreds of kilometers and complex geological terrain. “Our most significant finding is that most lowland rainforest insects in New Guinea are not narrowly distributed eaters of specific plants as previously thought,” says Weiblen, “but are rather widespread eaters of widespread groups of plants.”

Nitrate in Lake Superior increases

(Geophysical Research Letters | 5.31.07)

Nitrate levels in Lake Superior, on the rise over the past century, are almost three percent of the way toward making the water unsafe to drink, according to a study by University of Minnesota researchers. The level of nitrate, which is produced by agricultural fertilizer and fossil fuel combustion, has increased in Lake Superior about five-fold since the earliest measurements in 1906.

Small amounts of nitrate are harmless, but too much can reduce oxygen levels in blood, which poses a risk to infants and children or adults with lung or cardiovascular disease. Long-term exposure to nitrate has also been linked to cancer. “We’re still a long way from drinking water advisories based on nitrate for Lake Superior, but it’s not too early to give this situation more attention,” says lead author Robert Sterner, professor of ecology, evolution and behavior. “We cannot easily or quickly reverse trends in this enormous lake.”

Discovery may reduce need for fertilizers

(Science | 6.1.07)

Soybeans and other legumes “fix” their own nitrogen through a symbiotic relationship between roots and soil bacteria, reducing the need for nitrogen fertilizers. Professor Michael Sadowsky of the BioTechnology Institute has made a discovery about that relationship, which could yield farming practices that are better for the environment.

Using genome sequencing, Sadowsky and his colleagues found that some bacteria have alternate ways of entering and communicating with the legume plants; they enter the plant through the cracks between its main stem and branches as well as through cracks in the roots.

“This is a new paradigm; it tells us that bacteria have learned several ways to interact with their host plants in order for nitrogen fixation to happen,” Sadowsky says. “This gives us basic information we can use to tailor the interaction between bacteria and plants.” The study is co-authored by scientists from several French laboratories, the U.S. Department of Energy and the National Center for Soybean Biotechnology.

Chimp conservation tied to Gombe research

(Conservation Biology | 6.07)

Anne Pusey, professor of ecology, evolution and behavior, is co-author, along with Jane Goodall, Lilian Pintea, Michael Wilson and Shadrack Kamenya, of a study describing how research on chimpanzee behavior initiated by Goodall at Gombe National Park in Tanzania in 1960 has contributed to conservation.

“Presenting the findings of this research in popular media has educated a broad public about the remarkable nature of our primate cousins while raising awareness of the many threats they face across Africa,” Pusey says. The researchers identified a handful of benefits of the research for conservation: upgrading Gombe from a game preserve to a national park; attracting financial support for the research at Gombe and other parks in Tanzania; making discoveries about social structure and habitat use; gathering data on the chimpanzee population in Gombe over the past 40 years; and identifying factors that affect population size.

Lithium could treat degenerative disease

(PLoS Medicine | 5.29.07)

Lithium, a drug used for decades to treat bipolar disorder, may be useful for treating spinocerebellar ataxia, a genetic neuromuscular disease, according to a study co-authored by Harry Orr, professor of genetics, cell biology and development, and Huda Zoghbi, Baylor College of Medicine. The study was conducted in mice bred with the SCA1 gene and given dietary lithium before and after the onset of the disease. In all cases, the lithium improved coordination, learning and memory. The researchers believe it may also be beneficial for similar conditions. It did not extend lifespan, however, and is not likely to represent a cure. Since lithium is already approved for use in humans, clinical trials in patients could begin soon.

Microbes promise greener chemistry

Assistant professors Daniel Bond and Jeffrey Gralnick of the BioTechnology Institute have received a $100,000 award from the Cargill Higher Education Partnership Initiative to collaborate on a microbial biocatalysis study. “The central aim of this proposal is to combine metabolic and electrical engineering to allow bacterial strains attached to electrode surfaces to overcome key limitations in biocatalysis and bioprocessing,” Bond says. “Understanding the linkages between the internal and external electrical wiring of microorganisms will provide powerful tools for the future of green chemistry.”

Producing biofuel and clean water

Cedar Creek researchers are joining forces with the U.S. Geological Survey to determine if restored prairie areas can function simultaneously as water filtration systems below ground and biofuel production systems above ground. The research, funded by a $1 million grant, will also look at how to expand wildlife corridors and absorb greenhouse gases. Led by Clarence Lehman the project includes University researchers David Tilman, John Nieber, Jared Trost and Troy Mielke.

The making of a male

(PLoS Genetics | 4.20.07)

David Zarkower, associate professor of genetics, cell biology and development, has published a study about the discovery of a protein that localizes the sex chromosomes during meiosis in mice, in a structure called the XY body or “sex body.” This is a special domain of chromatin found only in male mammals during spermatogenesis. The finding shows that the protein (Dmrt7), required for male but not female meiosis, is found in all mammals but not in other vertebrates, and is apparently involved in modifying the sex chromatin.