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Archive - Nov 18, 2009

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Female Mountain Goats May Be Conflicted over Mate Choice

Mountain goats are no exception to the general rule among mammals that larger males sire more and healthier offspring. But University of Alberta researcher Dr. David Coltman and colleagues have recently found a genetic quirk that might make female mountain goats think twice about their prospective mates. The larger males pass their physical attributes and mating success to their male heirs. But Dr. Coltman's data shows the daughters of these larger males are routinely smaller and less fit than females produced by physically more modest fathers. Life on the side of a mountain favors bigger, healthier animals, both male and female. Dr. Coltman's research shows that this anomaly could have implications for female mate choice, because a female that mates with a large, dominant male can expect to have larger sons, but smaller and less fit daughters. The research also poses the question of why female offspring sired by the dominant male would be compromised. Another question the study raises is: what if any consideration does the size of their daughters have for would-be mothers? Could this be a factor weighed by a sexually mature female when courted by males that come in a variety of sizes? This study was featured as the cover story of the November 22 issue of the Proceedings of the Royal Society B. [Press release] [PRS abstract]

Nano “Fly Paper” Captures Metastatic Cancer Cells for Testing

Just as fly paper captures insects, an innovative new device with nano-sized features developed by researchers at UCLA is able to capture cancer cells in the blood that have broken off from a tumor. These cells, known as circulating tumor cells, or CTCs, can provide critical information for examining and diagnosing cancer metastasis, determining patient prognosis, and monitoring the effectiveness of therapies. The current gold standard for examining the disease status of tumors is an analysis of metastatic solid biopsy samples, but in the early stages of metastasis, it is often difficult to identify a biopsy site. By capturing CTCs, doctors can essentially perform a "liquid" biopsy, allowing for early detection and diagnosis, as well as improved treatment monitoring. To date, several methods have been developed to track these cells, but the UCLA team's novel "fly paper" approach may be faster and cheaper than others, and it appears to capture far more CTCs. The UCLA team developed a 1-by-2-centimeter silicon chip that is covered with densely packed nanopillars and looks like a shag carpet. To test cell-capture performance, researchers incubated the nanopillar chip in a culture medium with breast cancer cells. As a control, they performed a parallel experiment with a cell-capture method that uses a chip with a flat surface. Both structures were coated with anti-EpCAM, an antibody that can help recognize and capture tumor cells. The researchers found that the cell-capture yields for the UCLA nanopillar chip were significantly higher; the device captured 45 to 65 percent of the cancer cells in the medium, compared with only 4 to 14 percent for the flat device. The time required for CTC detection using CellSearch, a technology currently approved by the U.S.

Evolution of Highly Toxic Box Jellyfish

With thousands of stinging cells that can emit deadly venom from tentacles that can reach ten feet in length, the fifty or so species of box jellyfish have long been of interest to scientists and to the public. Yet little has been known about the evolution of this early branch in the animal tree of life. An international team of researchers has now largely unraveled the evolutionary relationships among the various species of box jellyfish, thereby providing insight into the evolution of their toxicity. “By determining the relationships among the different box jellyfish, some of which are capable of killing a healthy human, this study can help in the future development of antivenoms and treatments for their stings,” said Dr. Allen Collins, a specialist in Cnidaria, the phylum of animals that includes box jellyfish, and senior author of the report. “Researchers will now be able to make more informed choices about organisms for future venom studies, and make predictions on which species are likely to be of public health concern in addition to the known culprits.” Box jellies--also called sea wasps, stingers, or fire jellies--live primarily in warm coastal waters around the world. They are particularly well known in Australia, the Philippines and the rest of Southeast Asia, but they also occur in Hawaii and in waters off the United States Gulf and East Coasts. Their toxicity varies among species and ranges from being completely harmless to humans to causing death within minutes after a sting. Beyond their toxicity, box jellyfish have other interesting characteristics. Some species, for instance, have as many as 24 eyes, capable of sensing light and forming an image of their surroundings.