T.rex 'followed its nose' while hunting

Tyrannosaurus rex, a theropod from the Late Cretaceous of North America, pencil drawing. Image: Wikipedia.

Although we know quite a bit about the lifestyle of dinosaur; where they lived, what they ate, how they walked, not much was known about their sense of smell, until now.

Scientists at the University of Calgary and the Royal Tyrrell Museum are providing new insight into the sense of smell of carnivorous dinosaurs and primitive birds in a research paper published in the British journal Proceedings of the Royal Society B.

The study, by U of C paleontologist Darla Zelenitsky and Royal Tyrrell Museum curator of dinosaur palaeoecology François Therrien, is the first time that the sense of smell has been evaluated in prehistoric meat-eating dinosaurs. They found that Tyrannosaurus rex had the best nose of all meat-eating dinosaurs, and their results tone down the reputation of T. rex as a scavenger.

The researchers looked at the importance of the sense of smell among various meat-eating dinosaurs, also called theropods, based on the size of their olfactory bulbs, the part of the brain associated with the sense of smell. Although the brains of dinosaurs are not preserved, the impressions they left on skull bones or the space they occupied in the skull reveals the size and shape of the different parts of the brain. Zelenitsky and Therrien CT-scanned and measured the skulls of a wide variety of theropod dinosaurs, including raptors and ostrich-like dinosaurs, as well as the primitive bird Archaeopteryx.

"T. rex has previously been accused of being a scavenger due to its keen sniffer, although its nose may point to alternative lifestyles based on what we see in living animals" says Zelenitsky, the lead investigator on the study. "Large olfactory bulbs are found in living birds and mammals that rely heavily on smell to find meat, in animals that are active at night, and in those animals that patrol large areas. Although the king of carnivorous dinosaurs wouldn't have passed on scavenging a free dead meal, it may have used its sense of smell to strike at night or to navigate through large territories to find its next victim."
In addition to providing clues about the biology and behavior of the ancient predators, the study also reveals some surprising information about the sense of smell in the ancestors of modern birds.

Therrien and Zelenitsky found that the extinct bird Archaeopteryx, known to have evolved from small meat-eating dinosaurs, had an olfactory bulb size comparable to most theropod dinosaurs. Although sight is very good in most birds today, their sense of smell is usually poor, a pattern that does not hold true in the ancestry of living birds.

"Our results tell us that the sense of smell in early birds was not inferior to that of meat-eating dinosaurs," says Therrien. "Although it had been previously suggested that smell had become less important than eye sight in the ancestors of birds, we have shown that this wasn't so. The primitive bird Archaeopteryx had a sense of smell comparable to meat-eating dinosaurs, while at the same time it had very good eye sight. The sense of smell must have become less important at some point during the evolution of those birds more advanced than Archaeopteryx."

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Nanoparticles Target Multiple Cancer Genes, Shrink Tumors More Effectively

“It is a very selective and targeted approach,” said Gavin Robertson, Ph.D., who led the team of researchers from the Penn State College of Medicine. “And unlike most other cancer drugs that inadvertently affect a bunch of proteins, we are able to knock out single genes.”
The Penn State researchers speculated that siRNA could turn off the two cancer-causing genes and potentially treat the deadly disease more effectively. “siRNA checks the expression of the two genes, which then lowers the abnormal levels of the cancer causing proteins in cells,” explained Dr. Robertson. This research appears in the journal Cancer Research.

In recent years, researchers have zeroed in on two key genes—B-Raf and Akt3—that play key roles in the development of melanoma. Mutations in the B-Raf gene, the most frequently mutated gene in melanoma, lead to the production of a mutant form of the B-Raf protein, which then helps mole cells survive and grow. B-Raf mutations alone, however, do not trigger melanoma development. That event requires a second protein, called Akt3, that regulates the activity of the mutated B-Raf, which aids the development of melanoma. The siRNA agents used in this study specifically target Akt3 and the mutant B-Raf and therefore do not affect normal cells.

However, although knocking out specific genes may seem like a straightforward task, delivering the siRNA drug to cancerous cells is another story, because not only do protective layers in the skin keep drugs out but also chemicals in the skin quickly degrade the siRNA. To clear these two hurdles, Dr. Robertson and his team engineered lipid-based nanoparticles that can incorporate siRNA into their hollow interiors. The researchers then used a portable ultrasound device to temporarily create microscopic holes in the surface of the skin, allowing the drug-filled particles to leak into tumor cells beneath.

When the researchers exposed lab-generated skin containing early cancerous lesions to the treatment 10 days after the skin was created, the siRNA reduced the ability of cells containing the mutant B-Raf to multiply by nearly 60 to 70 percent and more than halved the size of lesions after 3 weeks. “This is essentially human skin with human melanoma cells, which provides an accurate picture of how the drug is acting,” said Dr. Robertson.

Mice with melanoma that underwent the same treatment had their tumors shrink by nearly 30 percent when only the mutant B-Raf was targeted. There was no difference in the development of melanoma when the Akt3 gene alone was targeted, although existing tumors shrank by about 10 to 15 percent in 2 weeks. However, when the researchers targeted both Akt3 and mutant B-Raf at the same time, they found that tumors in the mice shrank about 60 to 70 percent more than when either gene was targeted alone.

“If you knock down each of these two genes separately, you are able to reduce tumor development somewhat,” Dr. Robertson said. “But knocking them down together leads to synergistic reduction of tumor development.”

This work, which was supported in part by the National Cancer Institute, was detailed in the paper “Targeting V600EB-Raf and Akt3 Using Nanoliposomal-Small Interfering RNA Inhibits Cutaneous Melanocytic Lesion Development.” An abstract of this paper is available at the journal’s Web site (http://dx.doi.org/doi:10.1158/0008-5472.CAN-07-6614).

Provided by National Cancer Institute

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Pipeline bursts at Alaska's Prudhoe Bay

By Wesley Loy | Anchorage Daily News

BP's old bugaboo, corrosion, might have struck again in the giant Prudhoe Bay oil field.

The oil company suspects corrosion contributed to a pressurized natural gas pipeline blowing apart on Sept. 29, BP spokesman Steve Rinehart said.

No one was hurt, though some workers were in the vicinity when the line ruptured violently, hurling a length of pipe across the tundra.

Automated safety systems and field workers rushed to shut down the pipeline, which was 8 inches in diameter and carried gas for shooting underground, part of a technique to help coax out additional crude oil.

The incident forced the shutdown of two well pads producing about 5,000 barrels of oil per day -- less than 1 percent of total North Slope oil output. The pads remained out of service on Friday.

BP will do a metallurgical analysis of the failed pipe before declaring corrosion as the culprit for the rupture, Rinehart said. Some possibilities have been ruled out, he said, such as a bad weld.

Investigators found the corrosion had attacked the outside surface of the above-ground pipe at a point where insulation that normally jackets the line was missing, Rinehart said.

Moisture had wicked beneath the exposed insulation and come into contact with the steel, causing corrosion that can eat through metal and weaken a pipeline, he said.

As a safety measure, BP workers will look for any pipes that might be in a similar condition, Rinehart said.

State and federal pipeline regulators are investigating the pipeline rupture.

BP runs Prudhoe, the nation's largest oil field, on behalf of itself and other owners including Conoco Phillips and Exxon Mobil.

Corrosion has bedeviled BP since 2006, when oil leaks from major Prudhoe pipelines drew intense regulatory and congressional scrutiny of the London-based company. The lines were found to be riddled with corrosion.

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