Tuesday, March 5, 2013

Camel ancestors lived in the Arctic

Fossils on Ellesmere Island suggest famous desert dweller got its start in the cold

Fossils on Ellesmere Island suggest famous desert dweller got its start in the cold

By Erin Wayman

Web edition: March 5, 2013

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COLD CLIMATE CAMELS

Giant camels, as seen in this illustration, roamed the Arctic more than 3 million years ago when the region was forested, a new study suggests.

Credit: Julius Csotonyi

The desert?s most iconic creature may be a snow lover at heart. Scientists have unearthed fossils of a giant camel that roamed the Arctic more than 3 million years ago, when the region was warmer than today and blanketed by a boreal forest. The discovery, reported online March 5 in Nature Communications, suggests modern camels probably descended from a cold-dwelling ancestor.

?I?m not surprised you?re finding a camel up there,? says Christine Janis, a paleobiologist at Brown University in Providence, R.I., who was not involved in the discovery. Many camel characteristics, such as long legs for efficient walking and fat-storing humps, may be adaptations to living in environments like the Arctic, where food is sparse and distributed at distant intervals, she says.

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These fragments of a giant camel?s leg bone were discovered on Ellesmere Island in the Canadian Arctic.

Credit: Martin Lipman/Canadian Museum of Nature

A team led by paleobiologist Natalia Rybczynski of the Canadian Museum of Nature in Ottawa found roughly 30 fragments of a camel?s lower leg bone on Ellesmere Island in the Canadian Arctic. The researchers estimate the animal?s leg was 29 percent larger than a modern camel?s. Back-of-the-envelope calculations indicate the beast stood 2.7 meters at its shoulders, Rybcynski says, and weighed up to 900 kilograms.

The researchers determined that the fragments belonged to a camel by comparing collagen proteins extracted from the bones to collagen from 37 modern mammal species. The dromedary camel was the best match.

The protein was also nearly identical to collagen from more-recent camel fossils found in the Yukon Territory, which date to between 2.6 million and 10,000 years ago. In 2011, Rybczynski?s coauthor C. Richard Harington, also of the Canadian Museum of Nature, concluded in Quaternary Science Reviews that the Yukon bones resemble an extinct camel of the genus Paracamelus that lived in Eurasia as early as about 7.5 million years ago.

Scientists think Paracamelus gave rise to modern camels. Since the camel lineage originated in North America, Rybczynski says Paracamelus probably did too, crossing into Eurasia when a land bridge connected Alaska and Russia. Scientists had thought that these camels evolved from an ancestor that lived in North America?s lower latitudes. Instead, she says, Paracamelus? connection to the Yukon and Ellesmere Island fossils suggests the camel ancestor came from the forests of the far north.

Source: http://www.sciencenews.org/view/generic/id/348716/title/Camel_ancestors_lived_in_the_Arctic

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Friday, March 1, 2013

Researchers identify genetic variation behind acute myeloid leukemia treatment success

Researchers identify genetic variation behind acute myeloid leukemia treatment success

Wednesday, February 27, 2013

Researchers from the College of Pharmacy and Medical School working within the Masonic Cancer Center, University of Minnesota, have partnered to identify genetic variations that may help signal which acute myeloid leukemia (AML) patients will benefit or not benefit from one of the newest antileukemic agents.

Their study is published today in Clinical Cancer Research.

In the latest study, U of M researchers evaluated how inherited genetic polymorphisms in CD33, a protein that naturally occurs in most leukemia cells, could affect clinical outcomes of patients treated with an existing chemotherapy drug, gemtuzumab ozogamicin (GO), an immuno-conjugate between anti-CD33 antibody and a cytotoxin known as calicheamicin, which binds to CD33 on leukemic cells. As GO is internalized by leukemia cells, the cytotoxin is released, causing DNA damage and generating leukemic cell death.

In recent clinical trials GO has been shown to induce remission and improve survival in subset of patients with AML, however there is wide inter-patient variation in response.

Jatinder Lamba, Ph.D., and colleagues identified and evaluated three genetic variations of CD33 in two groups of patients with pediatric AML ? one group that received the drug GO, and one group that did not. They found that specific genetic variation in CD33 that significantly affected the clinical outcome of AML patients who received GO based chemotherapy.

"Understanding how genetics play a role in how drugs work is extremely useful, particularly for a drug like GO which has shown a very heterogeneous response in AML patients," said Jatinder Lamba, Ph.D., the study's lead author and a researcher who holds appointments in both the College of Pharmacy and the Masonic Cancer Center, University of Minnesota. "Our latest findings lead us to believe that genetic variation in CD33 influences how AML patients' leukemic cell responds to GO."

AML is a cancer of the blood and bone marrow, and is the second most common form of leukemia in children. Though the most common type of treatment for AML is chemotherapy, Lamba says the disease remains hard to treat and newer, more effective therapies are needed.

"The overall goal of our study was to use genetic data to predict beneficial or adverse response to a specific drug, thus opening up opportunities to use this information for drug optimization to achieve maximum therapeutic efficacy and minimum toxicity. Our hope is that our research could serve as a marker of prognostic significance for clinicians to select the therapy that has the greatest odds of being effective for individual patients based on their CD33 genotype."

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University of Minnesota Academic Health Center: http://www.ahc.umn.edu/

Thanks to University of Minnesota Academic Health Center for this article.

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Source: http://www.labspaces.net/127037/Researchers_identify_genetic_variation_behind_acute_myeloid_leukemia_treatment_success

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