Science and Medicine

Researchers Find Evidence of Teeth Loss in Ancestor of Whales



Genomic record matches fossil record in the whales’ common ancestor, say UC Riverside biologists

RIVERSIDE, Calif.—In contrast to a toothed whale, which retains teeth that aid in capturing prey, a living baleen whale (blue whale, fin whale, humpback, bowhead) has lost its teeth and must sift zooplankton and small fish from ocean waters with baleen or whalebone, a sieve-like structure in the upper jaw that filters food from large mouthfuls of seawater.

Based on previous anatomical and fossil data studies, scientists have widely believed that both the origin of baleen and the loss of teeth occurred in the common ancestor of baleen whales about 25 million years ago. Genetic evidence for these, however, was lacking.

Now biologists at the University of California, Riverside provide the first genetic evidence for the loss of mineralized teeth in the common ancestor of baleen whales. This genomic record, they argue, is fully compatible with the available fossil record showing that the origin of baleen and the loss of teeth both occurred in the common ancestor of modern baleen whales.

“We show that the genetic toolkit for enamel production was inactivated in the common ancestor of baleen whales,” said Mark Springer, a professor of biology, who led the research. “The loss of teeth in baleen whales marks an important transition in the evolutionary history of mammals, with the origin of baleen laying the foundation for the evolution of the largest animals on Earth.”

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New Device for Identifying Aggressive Breast Cancers



A new disposable device based on advances in microfluidics may help identify advanced breast cancer patients who are candidates for therapy with the drug trastuzumab (Herceptin). The device is described in the American Institute of Physics’ journal Biomicrofluidics.

Aggressive breast cancers with poor prognosis typically have abnormal levels of the protein HER2 (the tyrosine kinase human epidermal growth factor receptor 2). The new elastomeric, rubber-like device is designed to efficiently capture cancer cells overexpressing HER2 in circulating blood.

Finding a way to identify these cells is medically relevant because HER2 positive patients with early breast cancer have been found to significantly benefit from treatment with Herceptin or trastuzumab, the humanized monoclonal antibody against HER2, which can lower recurrence risk by about half. Given the cost ($50,000 - $65,000 per year in the United States) and possible side effects of Herceptin therapy, establishing HER2 status is crucial.

Current methodologies for determining HER2 status include immunohistochemistry and fluorescence in situ hybridization (FISH), both of which require biopsies. But biopsy-based testing may lead to ineffective treatment choices because in about 20% of breast cancers, the HER2 status of the primary tumor may differ from that of a metastatic tumor. This fact has made the noninvasive alternative of profiling circulating tumor cells a long-sought but elusive goal. Isolating circulating tumor cells, which are present at ratios as low as 1 to 10 per billion blood cells, is extremely challenging.

Recently, interest in microfluidic devices for capturing circulating tumor cells (CTCs) has intensified because of their greatly improved capabilities. A microfabricated device developed by researchers at the Massachusetts General Hospital and designed to bind to cells of epithelial origins (most cancers originate from epithelial tissues) circulating in the blood demonstrated near-perfect ability to isolate circulating tumor cells across a range of cancers.

In a study supported by the National Health and Medical Research Council Australia, Benjamin Thierry and colleagues at the Ian Wark Research Institute at the University of South Australia developed a plastic-based disposable microfluidic device offering several improvements for capturing circulating tumor cells. The device is designed to take advantage of the features of an organic silicone found in contact lenses and shampoos called polydimethylsiloxane (PDMS), which is compatible with soft molding techniques, transparent, and permeable to gasses.

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Stonehenge Boy was from the Mediterranean



The boy was buried with around 90 amber beads. Chemical tests on teeth from an ancient burial near Stonehenge indicate that the person in the grave grew up around the Mediterranean Sea.

The bones belong to a teenager who died 3,550 years ago and was buried with a distinctive amber necklace.

The conclusions come from analysis of different forms of the elements oxygen and strontium in his tooth enamel.

Analysis on a previous skeleton found near Stonehenge showed that that person was also a migrant to the area.

The findings will be discussed at a science symposium in London to mark the 175th anniversary of the British Geological Survey (BGS).

The “Boy with the Amber Necklace,” as he is known to archaeologists, was found in 2005, about 5 km southeast of Stonehenge on Boscombe Down.

The remains of the teenager were discovered next to a Bronze Age burial mound during roadwork for military housing.

“He’s around 14 or 15 years old and he’s buried with this beautiful necklace,” said Professor Jane Evans, head of archaeological science for the BGS. “The position of his burial, the fact he’s near Stonehenge, and the necklace all suggest he’s of significant status.”

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