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Archive - Aug 12, 2015

Mysterious Altitude Changes in Nighttime Flight Paths of Migrating Songbirds

A new mystery has been discovered in the migratory behavior of birds! Many songbirds travel long distances during their annual migrations, and it makes sense for them to do everything they can to conserve their energy during these journeys. Researchers have guessed that, for this reason, they might pick an altitude with favorable winds and stick with it rather than climbing and descending repeatedly, but there has been little data to back this up. In a study published online on August 12, 2015 in an open-access article in The Auk: Ornithological Advances, presenting the first full-altitude flight data for migrating songbirds, Dr. Melissa Bowlin of the University of Michigan-Dearborn and colleagues used radio transmitters to track the altitudes of migrating Swainson's thrushes (Catharus ustulatus)(image) and were surprised to find that the thrushes actually made repeated altitude adjustments of more than 100 meters over the course of their nighttime migratory flights. The reasons for these altitude changes are not clear, but the researchers have a few theories. The new article is titled “"Unexplained Altitude Changes in a Migrating Thrush: Long-Flight Altitude Data from Radiotelemetry.” Funded in part by the National Geographic Society, Dr. Bowlin and her colleagues captured 9 Swainson's thrushes in a small forest fragment in Illinois during spring migration season in 2011-13, outfitted them with transmitters, and followed them with a radio-tracking vehicle to gather altitude data once they took off on a migratory flight. "I really thought that the birds would mostly behave like commercial aircraft, ascending to a particular altitude, leveling off and cruising near that altitude, and then coming down just before they landed," explains Dr. Bowlin.

Hopkins Scientists Identify Nerve-Guiding Protein (Semaphorin 3D) That Aids Pancreatic Cancer Metastasis; Exosome Involvement a Possibility

Scientists at the Johns Hopkins Kimmel Cancer Center have identified a molecular partnership in pancreatic cancer cells that might help to explain how the disease spreads (metastasizes) in some cases. Their findings reveal urgently needed new targets to treat pancreatic cancer, which strikes nearly 50,000 people in the U.S. each year and has only a 5 percent survival rate five years after diagnosis. One of the molecular partners is annexin A2, a protein that scientists say was already linked to poor survival rates in these cancers. In a report published in the August 4, 2015 issue of Science Signaling, Lei Zheng, M.D., Ph.D., and his colleagues show that annexin A2 helps usher a protein called semaphorin 3D (Sema3D) out of pancreatic cancer cells. Once outside the cells, Sema3D joins with another molecule (plexin D1) to fuel the cancer's spread. The new article is titled “Semaphorin 3D Autocrine Signaling Mediates the Metastatic role of *Annexin A2 in Pancreatic Cancer.: Sema3D is a protein that guides the projecting arms of nerve cells, called axons, as the nerve cells grow and develop. In experiments with mice, the researchers calculated a seventy-fold drop in the amount of Sema3D secreted from mouse pancreatic cancer cells in animals that lacked annexin A2. In an experiment involving 23 mice, none of the annexin-free animals developed visible metastatic tumors. By contrast, 16 out of 17 mice that produced annexin A2 in their cells developed metastatic tumors in the liver, lungs or abdominal cavity. In a second group of experiments using human tissue from patients with pancreatic ductal adenocarcinoma, which accounts for more than 90 percent of pancreatic cancers, Dr.

Unique Scent Profile Is Crucial to Mother Antarctic Fur Seal Re-Locating Her Pup on Beach After Return from Food-Gathering Trips into Ocean

Researchers studying Antarctic fur seals have discovered the seals’ scent has a unique “profile” which enables them to recognize their offspring and family members. Until now, researchers had thought voice recognition was the most important means for finding their young, but now it is proven that scent also plays a crucial role. The results were published online on August 10, 201510 in PNAS. The article is titled “Chemical Fingerprints Encode Mother-Offspring Similarity, Colony Membership, Relatedness and Genetic Quality in Fur Seals.” The sense of smell and an animal’s scent is an important means of communication in the animal kingdom. This applies not only to social interactions, but also to territorial behavior, recognizing kin, and selecting a mate. However, understanding communication by smell is very challenging because of the mixture of chemicals on an animal’s skin. The odor emitted may be affected by hormones, the microbial flora, body condition and health, and environmental factors. A team of scientists from the Bielefeld University and the British Antarctic Survey sampled the skin and fur from dozens of mothers and their pups from two different fur seal colonies on the breeding beaches at Bird Island Research Station near the sub Antarctic Island of South Georgia. They found the scent of mothers and pups had similar characteristics. Dr. Martin Stoffel, lead author from Bielefeld University says: “Our results are surprising for a marine animal that spends more than 80% of its time at sea. They show that fur seal pups smell similar to their mothers, as many of the chemicals on their skin are shared and genetically encoded.