68 Moss Sex Points To Precursor of Pollination

Biology textbooks claim that the male moss mates by shedding sperm into a surrounding film of rainwater or dew—a haphazard strategy that arose in ancestral aquatic algae. But Swedish researchers announced in September that arthropods may in fact act as go-betweens. Such assisted reproduction was thought to have arisen about 140 million years ago, when insects began collecting and transferring pollen between flowering plants. It now seems that the tactic may have arisen far earlier, about 440 million to 470 million years ago, shortly after plants first colonized land.
Botanist Nils Cronberg of Lund University had suspected that mosses might use an intermediary to mate, so he designed a simple lab experiment to test his idea. He placed male and female mosses of the species Bryum argenteum in vials lined at the base with plaster of paris, which prevented the sperm from swimming. When males and females touched, fertilization occurred; when they were separated by a space three-fourths of an inch to one-and-a-half inches wide, it did not—unless mites and tiny arthropods called springtails were present to shuttle sperm between them. In a further experiment, the arthropods were allowed to choose between either sterile or fertile sperm-laden moss shoots; invariably, they chose the sugar- and fat-rich fertile shoots. "It seems that the animals are doing this because they get some sort of reward," says Cronberg. "This seems to be a phenomenon parallel with pollination."

Josie Glausiusz

Looking for a pollen-filled read? Check out DISCOVER's review of Pollen: The Hidden Sexuality of Flowers.


73 Electrical Signals Help Direct Wound Healing

In the mid-1800s, after wounding his arm, German physiologist Emil Du Bois-Reymond measured a small current at the site, which suggested that the injury triggered an electric signal. Since then biologists have made little progress in understanding where electricity fits into the myriad chemical and physical responses involved in wound healing. In July Min Zhao, professor of biomedical science at the University of Aberdeen in Scotland, announced that electricity is the dominant factor.
Using an electric current, Zhao and his colleagues were able to direct epithelial cells (like those in the skin and in mucus membranes) both to and from wounded tissue in mouse corneas. In addition, they showed that the speed of the migration is in direct proportion to the amount of voltage applied. It is too soon to endorse experimental therapies that employ electrical stimulation, Zhao says. Rather, his next step is to investigate the healing properties of electricity at the genetic level. His team has already identified two genes that are key players in cell migration. Next they will look for molecules and genes that assist in sensing an electric signal and in mediating the cell's response to it.

Nicholas Bakalar

Find out why electricity is essential to surviving as a living thing.

79 Worm Lives Without Guts

Over the course of evolution, Olavius algarvensis, a bizarre little worm living in sediments along the Mediterranean, appears to have lost its mouth, guts, and excretory organs. Instead, it relies on several species of bacteria that live beneath its skin, forming a web of cooperative relationships with one another and with their host. In September Nicole Dubilier of the Max Planck Institute in Germany and her colleagues reported that they had sequenced the DNA of four of the bacterial houseguests, revealing intimate details about their quid pro quo with the worm. "They're providing energy production," says Edward Rubin, head of the federal Joint Genome Institute in Walnut Creek, California, where the sequencing was done. "They feed the worm, they get rid of the worm's waste." In return, the bacteria get housing and transportation. This was the first genomic analysis of such a complex symbiotic relationship.

Ingfei Chen

80 New Monkey Genus Found in Tanzania

Biologists added a new branch to our primate family tree this year. Genetic studies of the kipunji, a threatened monkey in Tanzania, reveal that it belongs to a new primate genus—the first to be identified in 83 years. The grayish-brown monkey, which is about three feet long with a distinctive "honk-bark" call, lives in a highland habitat that had largely been ignored by scientists. Fewer than 1,000 kipunji may remain. According to Tim Davenport, a biologist for the Wildlife Conservation Society, "had we not found it now, it could very well have slipped into extinction without the scientific world ever knowing of it."

Jennifer Barone