Research Notes

Saturn's A Ring has oxygen, but not life

Data from the Cassini-Huygens satellite showing oxygen ions in the atmosphere around Saturn's rings suggests once again that molecular oxygen alone isn't a reliable indicator of whether a planet can support life.

(Photo by NASA, ESA, J. Clarke (Boston University) And J. Levay (STScI))

This finding and other data are outlined in two papers in the Feb. 25 issue of the journal Science co-authored by engineering professors Tamas Gombosi, J. Hunter Waite and Kenneth Hansen; and T.E. Cravens from the University of Kansas. The papers belong to a series of publications on data collected by Cassini as it passed through the rings of Saturn July 1.

Molecular oxygen forms when two oxygen atoms bond together and is known in chemical shorthand as O2. On Earth, it is a continual by-product of photosynthesis, and animals need this oxygen for life. But in Saturn's atmosphere, molecular oxygen was created, without life present, through a chemical reaction with the sun's radiation and icy particles that comprise Saturn's rings.

Because Saturn's rings are made of ice, one would expect to find atoms derived from water, such as atomic oxygen (one atom) rather than O2, Waite says. In the paper, entitled "Oxygen Ions Observed Near Saturn's A Ring," however, the authors suggest the formation of molecular oxygen atmospheres happens more often in the outer solar system than expected. There is earlier evidence of molecular oxygen atmospheres elsewhere in the solar system—for instance, above the icy Galilean moons of Jupiter—he says.

Four College of Engineering (CoE) faculty members, including Department of Atmospheric, Oceanic and Space Sciences (AOSS) Professor Andrew Nagy, are involved in the Cassini mission to explore Saturn's rings and some of its moons. Waite leads the team operating the ion and neutral mass spectrometer, the instrument that detected and measured the molecular oxygen ions.

A second viewpoint paper called, "Saturn's Variable Magnetosphere," by Hansen and Gombosi, AOSS chair, reviews key findings from the other Cassini teams, including new information that contradicts data gathered 25 years ago when the spacecraft Voyager passed by the planet.
—Laura Bailey, News Service

Ill people often just as happy as healthy ones

A new study finds that individuals with major medical conditions may be just as happy on average as those without an illness.

The finding adds to the growing body of evidence that ill and disabled people adapt to their conditions and show a resilience of spirit that many healthy people can't imagine. The study, published in the Journal of Experimental Psychology: General, was conducted by a team led by U-M Health System (UMHS) researchers.

The study is further evidence that people adapt emotionally to serious adversity, such as end-stage kidney failure, says senior author Dr. Peter Ubel, a professor of internal medicine and psychology, and a staff physician at the VA Ann Arbor Healthcare System.

The researchers made their surprising finding by having 49 pairs of dialysis patients and healthy people report their moods every few hours for a week, using a handheld personal digital assistant (PDA) such as a Palm. The patients all had been in dialysis for at least three months.

Lead author Jason Riis, a former U-M graduate student now at Princeton University, programmed the PDAs to beep randomly during each two-hour period of an entire week to prompt participants to report their moods by completing a series of ratings.

The researchers found that the healthy participants grossly underestimated the extent to which patients can adapt to dialysis. When asked to imagine that they were themselves dialysis patients, and to estimate the percentage of time that they would experience various positive and negative mood levels, the healthy participants assumed that they would be miserable.

Patients themselves seemed to underestimate their own adaptation. When asked to imagine the moods they would experience if they had never experienced kidney failure, the patients estimated that they would experience much better moods than those actually experienced by the healthy study participants.

The study does more than just give the first-ever glimpse into the hour-by-hour happiness of seriously ill and healthy people, Ubel says. It also may help influence policy-level and personal decisions about treatments for serious illnesses.

In addition to Ubel and Riis, the study team included Angela Fagerlin, a research investigator in the Department of Internal Medicine.
—Kara Gavin, UMHS Public Relations

African Americans underrepresented on corporate boards

Although two-thirds of Fortune 500 companies have at least one African American member on their corporate boards, only 8 percent of board seats are held by African Americans, according to a
U-M report.

Lynn Perry Wooten, clinical assistant professor of corporate strategy and management in the Stephen M. Ross School of Business, and colleague Erika Hayes James of the University of Virginia's Darden Graduate School of Business, found that of the 5,572 board seats for Fortune 500 companies, 449 belong to African Americans.

Those 449 seats are distributed among 255 African Americans, many of whom serve on more than one board. Forty-five serve on at least three boards, 60 are on two boards, and 150 serve on one.

African American men hold more than three times as many board seats as African American women, Wooten says. Of the 449 seats held by African Americans, 344 belong to men and 105 to women. In all, 201 African American men and 54 African American women hold at least one board seat.

Among all Fortune 500 companies, 102 have at least two African Americans on their boards, 233 have one African American board director, and 165 have none.

Wooten and James found that the higher a firm is ranked on the Fortune 500 list, the larger its board size and the more African American board members it has. Nearly 11 percent of the board directors of the top 100 companies are African American and 89 of those firms have at least one African American member.

In contrast, among the bottom 100 companies, 46 have at least one African American board member and African Americans hold 5.5 percent of the corporate board seats.

According to the study, tobacco (16.6 percent), food services (16.1), beverages (14.3), railroads (14.2) and waste management (13.6) are the industries with the highest representation of African American board directors.

The 2004 Census of African Americans on Corporate Boards report is the first of two studies on African American representation on corporate boards. The second report will be published this spring.

Both reports are sponsored by the Executive Leadership Council's Institute for Leadership Development & Research.
—Bernie DeGroat, News Service

Protein builds bigger, better bones in mice

Leaping tall buildings in a single bound may be out of the question, but the genetically engineered "supermice" in Ormond MacDougald's laboratory in the Medical School are definitely stronger than average. With bone mass up to four times greater than ordinary mice, these animals could hold the secret to new drugs for preventing or treating osteoporosis and other human diseases.

(Photo by Christina Bennett, Medical School)

The secret appears to be a secreted signaling protein called Wnt10b. Known to inhibit the development of adipose tissue in mice, Wnt10b also stimulates the growth of bone cells, according to a study published Feb. 21 in the Online Early Edition of the Proceedings of the National Academy of Sciences (PNAS).

High levels of Wnt10b expression in bone marrow directly increased bone mass and density in experimental mice, says MacDougald, associate professor of molecular and integrative physiology in the Medical School.

To study the effect of Wnt10b gene expression on tissue development, MacDougald's research team created an artificial sequence of DNA called a transgene linking Wnt10b to the FABP4 promoter, which is expressed in fatty tissue and in bone marrow. U-M scientists injected the transgene DNA into fertilized mouse eggs, and then bred mice that inherited the new gene to create the transgenic animals used in their research.

Dr. Kurt Hankenson, assistant professor of orthopedic surgery and laboratory animal medicine, and Christina Bennett, a U-M graduate student and first author of the PNAS paper, used a technology called micro-computerized tomography to scan femur (leg) bones from mice that inherited the FABP4-Wnt10b gene combination and compare them to scans from normal mice.

Bennett and Hankenson discovered that femurs from the transgenic mice had almost four times as much bone, and were mechanically stronger than femurs from control mice.

The research was funded by the National Institutes of Health, the U-M Diabetes Research and Training Center, the U-M Core Center for Musculoskeletal Disorders, and the Nathan Shock Mutant and Transgenic Rodent Core.

Additional U-M collaborators on the study include Kenneth Longo, a former research fellow in MacDougald's lab who is now a postdoctoral fellow in the School of Dentistry; and Wendy Wright, research associate in the Department of Molecular and Integrative Physiology.
—Sally Pobojewski, Medical School Communications