15. Stem Cell Setbacks Inspire New Methods
The year 2006—the tenth anniversary of Dolly the sheep's birth—began with a severe setback for stem cells' boosters. Some patients, scientists, and politicians had dared hope that cloning technology could be used to create donor-compatible stem cells that can help treat disease. But after learning that work by South Korean scientist Woo Suk Hwang had been faked, the journal Science retracted Hwang's landmark papers from 2004 and 2005, which reported the first human embryonic stem cells from cloned embryos.
Six months after the retraction, stem cell research received another blow. On July 19 President Bush vetoed H.R. 810, the Stem Cell Research Enhancement Act of 2005, which passed both the House and Senate by solid bipartisan majorities. The bill was put forth to loosen the restrictions Bush placed on human embryonic stem cell research on August 9, 2001, when he banned federal funding for work with any stem cell line created after that date. Since then, the vast majority of presidentially approved cell lines have proven unavailable, genetically abnormal, or otherwise difficult to work with. H.R. 810 would have allowed federal funding for work with certain stem cell lines created from excess frozen IVF embryos in the years since. (In polls, 60 percent of Americans disagreed with the president's veto.)
In the face of these setbacks, many scientists have focused on new methods of creating stem cell lines without destroying embryos. Traditionally, the process involves plucking the inner cell mass from a 5-day-old embryo known as a blastocyst (a round ball of 150 to 200 cells the size of a grain of sand), which destroys the embryo. In March however, German researchers—working in a political landscape even more restrictive than our own—reported turning sperm-producing cells from adult mouse testes into something very much like embryonic stem cells. A week later, U.S. scientists claimed to have done the same with human cells. In June Italian scientists announced the first human embryonic stem cells derived from parthenotes—embryo-like structures formed when an egg starts to divide on its own, with no sperm involved. In mammals, parthenotes are incapable of implanting in the womb to form a pregnancy and so are not considered potential human lives. Still, parthenotes can yield stem cells that closely match the genetic profile of the egg donor. In August Japanese scientists reported yet another method for making "personalized" cells without cloning: They treated mouse skin cells with four gene products active in embryonic stem cells and got the skin cells to revert to something much like the stem cells. In September a European team reported coaxing human embryonic stem cells from an "arrested" IVF embryo—one that had stopped dividing before it reached the blastocyst stage and thus died a natural death.
One of the biggest uproars followed a report from the biotech company Advanced Cell Technology (ACT), which described creating stem cells from a single cell taken from a 3-day-old, 8-cell human embryo. Single-cell biopsy procedures are done routinely in infertility labs and do not destroy the embryo, which "takes away the president's last excuse to oppose the research," ACT's vice president of research, Robert Lanza, told reporters.
Critics of embryo research responded with concerns that a biopsy might subtly harm an embryo, and wondered if even that single cell could have the potential to develop into an embryo and therefore a baby. They also attacked the company for a press release that claimed, "We have demonstrated, for the first time, that human embryonic stem cells can be generated without interfering with the embryo's potential for life." That release failed to mention that all 16 of the embryos used in these experiments had been destroyed. The ensuing controversy raised ire even on the pro-research side. "It's a big black eye if scientists are making false and fraudulent representations," Republican senator Arlen Specter, of Pennsylvania, told representatives of ACT during a Senate subcommittee hearing. Specter is a leading proponent of stem cell research and is currently trying to raise enough support for H.R. 810 to override the president's veto. "You made our job a lot tougher," he said.
55. New Mouse Organ Found
Mice are the most common lab animal, dissected so frequently that no biologist expects to stumble upon a new organ. But in April 2006, Hans-Reimer Rodewald, an immunologist at the University of Ulm in Germany, reported that mice have two thymus organs—one of them somehow undiscovered—and that both can produce immune cells called T lymphocytes. Located in the neck, the newfound organ is a fraction of the size of the long-familiar thymus found in the mouse's chest.
"When we first saw this, I didn't believe it," says Rodewald. To see whether it was a true functional organ, his team transplanted the small thymus from normal mice into mutant, thymus-free animals. When they injected these animals with a protein from the hepatitis B vaccine, the animals produced an immune response. Biologists are checking to see if they have overlooked a second human organ too.
Rabiya S. Tuma
64. HIV Precursor Found in the Wild
Researchers have long suspected that chimpanzees were the source of HIV-1, the AIDS virus, but proof from the wild was missing. A team led by Beatrice Hahn, professor of medicine at the University of Alabama in Birmingham, has now detected antibodies against the HIV-1 precursor—along with nucleic acids from the virus itself—in the scat of wild chimps. The HIV-1 progenitor appears to have originated in southern Cameroon, then made its way down the Sangha River to Kinshasa, Democratic Republic of the Congo, where the first documented infections in people occurred.
65. Gay Influence Found
Over the past decade, a handful of studies have hinted at a connection between male homosexuality and having older brothers. Now it appears that the key factor is sharing a biological mother.
Anthony Bogaert, a psychologist at Brock University in Ontario, set out to clarify the relative importance of biology and environment in determining sexual orientation. In a study of 944 men, published in July, he found that adopted brothers do not affect sexual orientation. Nor does it matter if a boy lives with his older biological brothers.
Bogaert estimates that one in seven gay men can attribute their homosexuality to having older biological brothers. Each increases the odds of being gay by one third. The base rate for homosexuality in men with no older brothers is estimated at about 4 percent, giving a man with one older brother a 5.2 percent chance of being gay.
"I was surprised that the effects were as strong as they were," Bogaert says. "What really hit home for me was finding evidence that there must be some kind of prenatal biological mechanism." The effect may be due to how a mother's immune system reacts to proteins produced by male fetuses—a possibility Bogaert hopes to explore in a future study.