 | Faculty Research
7/15/2002A Less Buggy World
By studying plants, a team that included University of Minnesota biologist George Weiblen has concluded that the world is far less buggy than some experts believed. The researchers’ findings indicate that the predicted number of total arthropod species (mostly insects, spiders, and crustaceans) on earth is far too high. Instead of more than 30 million, there are likely between 4 million and 6 million. In establishing a more accurate figure, scientists can better estimate the rate of biodiversity loss and refine strategies to preserve species. The study, funded by the National Science Foundation, looked at 51 rain-forest plants in New Guinea and more than 900 types of plant-eating insects. Contrary to prevailing thought, insects did not tend to feed on a single plant or a few closely related plants. Rather, they typically ate numerous plants of the same family. Estimates of plant-eating insects that had been based on plant surveys and the idea that insects were specific in their feeding had to be revised downward. Researchers extrapolated their findings to all arthropods to come up with the new figure, which closely matches estimates based on insect samples taken in tropical forests. The total number of species of all kinds on earth is unknown, with estimates ranging from 6 million or 7 million to more than 50 million. Of the 1.8 million species scientifically described thus far, about half are arthropods. The study was reported in the April 25 issue of Nature.
Classroom Connection
Students who enjoy their classrooms and classmates appear to have a lower incidence of violence, substance abuse, suicide, sexual activity, and other risky health behaviors, according to analysis at the University of Minnesota. The analysis of data from the National Longitudinal Study of Adolescent Health follows earlier University findings that students who feel connected in school have significantly lower incidence of risky behavior. The new study, released April 11 and led by Dr. Robert Blum, looked at what creates that feeling of "connectedness." Among the findings is that classroom management—getting students to care about the subject, the assignments, and each other—is far more important than class size, the type or location of a school, or the number of experienced or highly educated teachers at a school. As overall size of a school increases beyond the optimal, however, students feel more alienated. The study concluded that schools of fewer than 600 students best foster feelings of connectedness but, due to a lack of resources, experience lower academic achievement than schools with 600 to 1,200 students. In schools with enrollment larger than 1,200, achievement falls off, along with the feeling of being connected. The study was performed with written surveys filled out by more than 71,000 students during the 1994–95 school year, along with administrative questionnaires about the schools. The study was published in the April issue of the Journal of School Health (www.jsh.org) and as a report Improving the Odds: The untapped power of schools to improve the health of teens, which includes strategies for parents, teachers, and administrators for increasing school connection. The report is available at http://allaboutkids.umn.edu/.
Bile on the Brain
An acid found in the bile of gall bladders may be an ideal natural treatment for stroke victims and others, according to a study at the University of Minnesota and the University of Lisbon in Portugal. In trials with rats, tauroursodeoxycholic acid (TUDCA) used within an hour of an induced stroke resulted in a 50 percent reduction in brain damage compared with untreated rats. The molecule apparently disrupted the process of brain-cell death and essentially protected the cells from damage. This finding led study author Dr. Clifford Steer to speculate that TUDCA could be used to fight other degenerative brain diseases. A follow-up study by Minnesota researchers on Parkinson’s disease is ready for publication, and studies on feeding TUDCA to mice with induced Alzheimer’s and Huntington’s diseases are planned. TUDCA is currently used to treat a form of cirrhosis and is being investigated in various other liver ailments. The stroke study was reported in the April issue of the Journal of Cerebral Blood Flow and Metabolism.
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