Friday, May 14, 2010

A SHRUNKEN GIANT

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In 1895, the sister of an eccentric palaeontologist called Franz Baron Nopcsa discovered small dinosaur bones on their family estate in Transylvania. Nopcsa interpreted these as the remains of dwarfed animals that had once lived on an island. Among these finds were a number of bones belonging to a sauropod dinosaur which Nopcsa named Magyarosaurus dacus, after his native country.

A team of scientists led by Koen Stein and Professor Dr. Martin Sander from the University of Bonn, decided to cut up the fossil bones of the dwarfed dinosaur and study their microstructure. "It's astonishing that the microanatomy of these bones has been preserved for us to study after 70 million years," says Stein, who carried out the research as part of his PhD studies. "Bone is a living tissue, and throughout an animal's life it is constantly dissipating and building up again." Humans, for example, have completely resorbed and rebuilt their skeleton by the time they are fully grown. This also occurred in sauropod dinosaurs. "We were able to distinguish these rebuilding features in Magyarosaurus, which prove that the little dinosaur was fully grown," Koen Stein explains.

Over the years, palaeontologists have frequently debated the question of whether or not the Magyarosaurus was a dwarf. Martin Sander, spokesperson of the Research Group on Sauropod Biology funded by Germany's central research funding foundation the DFG (Deutsche Forschungsgemeinschaft) notes, "An animal the size of a horse may not seem like a dwarf to most people but, in sauropod terms, it's tiny!" When Magyarosaurus was discovered in Transylvania (then part of the Austro-Hungarian Empire), the palaeontologist Nopcsa advanced the idea that Magyarosaurus was an island dwarf, but he could not prove it back then, at the beginning of the 20th century. Many discoveries have since indicated that his theory might be correct, especially the fossils of dwarf elephants and hippopotamuses found on Mediterranean islands like Sicily, Malta and Cyprus.

However, scientists first pursued a different theory. For in the subsequent decades, other researchers found big sauropod bones on the Transylvanian site. They therefore concluded that Magyarosaurus was simply a youngster, while the larger bones came from fully grown adults.

The study now being published provides conclusive evidence that Nopcsa's hunch had been right all along. "Our study shows that dinosaurs on islands were subject to the same ecological and evolutionary processes that shape modern mammals," explains Martin Sander. "We were also able to demonstrate that the bigger bones found in that area belong to a different dinosaur species." Whether they come from stray animals who swam to the island from the mainland, or from large ancestors of the dwarf Magyarosaurus, remains a secret shrouded in the mists of pre-historic time.

(Photo: Mihai Dumbrava, liliensternus.deviantart.com)

University of Bonn

RESURRECTED MAMMOTH BLOOD VERY COOL

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A team of international researchers has brought the primary component of mammoth blood back to life using ancient DNA preserved in bones from Siberian specimens 25,000 to 43,000 years old.

Studies of recreated mammoth haemoglobin, published Monday 3 May in Nature Genetics, reveal special evolutionary adaptations that allowed the mammoth to cool its extremities down in harsh Arctic conditions to minimise heat loss.

"It has been remarkable to bring a complex protein from an extinct species, such as the mammoth, back to life," says Professor Alan Cooper, Director of the Australian Centre for Ancient DNA (ACAD) at the University of Adelaide, where the mammoth haemoglobin sequences were determined.

"This is true palaeobiology, as we can study and measure how these animals functioned as if they were alive today."

Professor Cooper is an Australian Research Council Future Fellow and a member of the University's Environment Institute.

"We've managed to uncover physiological attributes of an animal that hasn't existed for thousands of years," says team leader Professor Kevin Campbell of the University of Manitoba, Canada. "Our approach opens the way to studying the biomolecular and physiological characteristics of extinct species, even for features that leave no trace in the fossil record."

The project began over seven years ago when Professor Campbell contacted Professor Cooper, who was then based at the University of Oxford, to suggest resurrecting mammoth haemoglobin.

"At the time, I thought 'what a great idea' – but it's never going to work," says Professor Cooper. "Still, bringing an extinct protein back to life is such an important concept, we've got to try it."

The team converted the mammoth haemoglobin DNA sequences into RNA, and inserted them into modern-day E. coli bacteria, which then manufactured the authentic mammoth protein.

"The resulting haemoglobin molecules are no different than 'going back in time' and taking a blood sample from a real mammoth," says Professor Campbell.

The team used modern scientific physiological tests and chemical modelling to characterise the biochemical properties that confer mammoths with physiological cold tolerance.

Team member Professor Roy Weber of the University of Aarhus, Denmark, who performed the physiological testing on the mammoth proteins, says the findings help show how the mammoth survived the extreme Arctic cold.

"Three highly unusual changes in the protein sequence allowed the mammoth's blood to deliver oxygen to cells even at very low temperatures, something that indicates adaptation to the Arctic environment," Professor Weber says.

"We can now apply similar approaches to other extinct species, such as Australian marsupials," says team member Dr Jeremy Austin, ACAD Deputy Director, who is currently using ancient DNA to study the evolution and extinction of the thylacine and Tasmanian Devil.

(Photo: Ansgar Philippsen)

University of Adelaide

SLEEPING WELL AT 100 YEARS OF AGE: STUDY SEARCHES FOR THE SECRETS TO HEALTHY LONGEVITY

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A study in the May 1 issue of the journal SLEEP is the first to examine sleep issues in a large sample of exceptionally old adults, including nearly 2,800 people who were 100 years of age and older.

Results show that about 65 percent of the sample reported that their sleep quality was good or very good, and the weighted average daily sleep time was about 7.5 hours including naps. Surprisingly, the oldest adults aged 100 and above were 70 percent more likely to report good sleep quality than younger participants aged 65 to 79, after controlling for variables such as demographic characteristics, socioeconomic status and health conditions. Men were 23 percent more likely than women to report sleeping well.

Health problems were associated with worse sleep quality, as participants with self-rated poor health were 46 percent less likely to report sleeping well. The odds of reporting good sleep quality also were lower in people who often felt anxious, had at least one chronic disease or struggled with everyday tasks.

“Age and health conditions are the two most important factors associated with self-reported sleep quality and duration,” said principal investigator and lead author of the study Danan Gu, PhD, faculty of the Nohad A. Toulan School of Urban Studies and Planning at Portland State University in Oregon.

The study involved an analysis of data from the 2005 wave of the Chinese Longitudinal Healthy Longevity Survey. The sample was composed of 15,638 adults aged 65 and older, including 3,927 who were between 90 and 99 years of age, and 2,794 who were 100 years of age and older. Participants were spread across 22 provinces in mainland China.

According to the authors, China’s population of more than 1.3 billion people includes the largest elderly population in the world, making the country a valuable resource for studying healthy longevity. The World Bank estimates that China has nearly 40.5 million people who are 75 years of age and older.

Sleep quality was reported in response to the question, “How do you rate your sleep quality recently?” Typical daily sleep duration was reported by answering the question, “How many hours on average do you sleep every day including napping?” Additional data were collected with other socio-demographic and health status measures. All information was obtained through in-home interviews.

The study also found that access to healthcare and economic status were strongly related to good sleep quality. Participants were 84 percent more likely to report sleeping well if they had adequate medical service, and they were 56 percent more likely to report good sleep quality if their family was in good economic condition.

“The majority of healthy elders could experience satisfactory sleep quality,” said Gu. “Sleep problems at oldest-old ages likely arise from a variety of physiological and psychosocial factors rather than aging per se.”

Adults aged 80 and over tended to have a sleep duration that was either shorter or longer than adults aged 65 to 79, which was primarily due to deteriorating health. Controlling for health conditions showed that participants who were 100 years of age and older were less likely than the youngest elders to sleep for five or fewer hours per day, but they were almost three times more likely to sleep for 10 hour or more.

The authors emphasized that the cross-sectional nature of the study did not allow for an exploration of causality. However, they suspect that there is a bidirectional relationship between sleep quality and healthy longevity. At the end of 2010 data should be available from the 2008-2009 wave of the survey, which will allow for comparisons with the 2005 data.

American Academy of Sleep Medicine

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