The Super-Strong Mice

A team of geneticists has tweaked the genes of mice and worms to create animals with muscles that are twice as strong as normal.

Researchers from the Salk Institute for Biological Studies and two Swiss institutions, Ecole Polytechnique Federale de Lausanne (EPFL) and the University of Lausanne teamed up for the study, which could lead to the development of treatments for muscle degeneration in people who can't exercise.

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The team created the super-strong high endurance creatures by suppressing a natural muscle growth inhibitor. Genome regulator NCoR1 is a molecular brake that decreases activity of certain genes. This brake can be "released" through mutation or using chemicals and this, in turn, reactivates gene circuits to provide more energy to muscle and enhance its activity. This lead to the creation of super mice with muscles that are twice as strong as those of regular mice, even when the muscle was inactive.

Ronald M Evans, a professor at Salk's Gene Expression Lab, says: "There are now ways to develop drugs for people who are unable to exercise due to obesity or other health complications, such as diabetes, immobility and frailty. We can now engineer specific gene networks in muscle to give the benefits of exercise to sedentary mice."

Researchers experimented with both mice and nematodes, genetically manipulating the offspring of these species to repress NCoR1, the muscle build-up inhibitor. Without the inhibitor, the muscle develops much more effectively.

The muscly mice were able to run faster and longer before showing signs of fatigue. They also exhibited better cold tolerance. Similar results were seen in nematode worms, which let the researchers conclude that their results could be relevant to a range of living creatures.

Under the microscope the muscles could be seen to be bigger, with denser fibres and with cells that had more mitochondria, the cellular organelles that deliver energy to the muscles. So far the researchers haven't found any harmful side effects associated with eliminating the NCoR1 receptor from muscle and fat tissue, and are now investigating drug molecules that could be used to reduce the receptor's effectiveness. Johan Auwerx, the lead author from EPFL, said: "This could be used to combat muscle weakness in the elderly, which leads to falls and contributes to hospitalisations. In addition, we think that this could be used as a basis for developing a treatment for genetic muscular dystrophy."

He added that if these results are confirmed in humans, there's no question they will attract interest from athletes as well as medical experts.

The study was published in the journal Cell.

Environment Clean Generations

Climate Warming, Animals and Plants Shrinking

Contradicting a century-old hypothesis, increased global carbon dioxide levels seem to be shrinking plants instead of fostering their growth. Animals from polar bears to marine iguanas are being stunted too.

In 1896, Svante Arrhenius published calculations predicting that doubling CO2 levels would trigger a global temperatures increase of about 5-6 degrees C.

"We would then have some right to indulge in the pleasant belief that our descendants, albeit after many generations, might live under a milder sky and in less barren surroundings than is our lot at present," Arrhenius said during a lecture that same year.

But it seems reality hasn't lived up to Arrhenius' verdant dreams of vigorous vegetation.

"Plants were expected to get larger with increased atmospheric carbon dioxide," but changes in temperature, humidity and nutrient availability seem to have trumped the benefits of increased CO2, said researchers from the National University of Singapore in the journal Nature Climate Change.

Forty-five percent of the species studied now reach smaller adult sizes than they did in the recent past. The researchers, led by Jennifer Sheridan and David Bickford, point to climate change induced warmer temperatures and changing habitats are possible culprits in the case of the shrinking creatures.

"We do not yet know the exact mechanisms involved, or why some organisms are getting smaller while others are unaffected". "Until we understand more, we could be risking negative consequences that we can't yet quantify."

Environment-Clean-Generations

The change was dramatic in cold-blooded animals. Only two decades of warmer temperatures were enough to make reptile runts.

An increase of only one degree Celsius caused nearly a 10 percent increase in metabolism. Greater use of energy resulted in tiny tortoises and little lizards.

Fish are smaller now too. Though overfishing has played a part in reducing piscine proportions, the researchers also point to experimental results showing that warmer temperatures also stunt fish growth.

Warm-blooded animals weren't immune from the climate change caused size change.

Many birds are now less bulky, including passerines (the order that includes cardinals, blue jays, and crows) as well as goshawks and gulls.

Mammals have been miniaturized too. Soay sheep are scrawny. Red dear are runts. And polar bears are puny, compared to historical records.

This isn't the first time this has happened in Earth's history.

Fifty-five million years ago, a warming event similar to the current climate change correlated to beetles, bees, spiders, wasps and ants shrinking by 50 to 75 percent over several thousand years.

Woodrats and squirrels also shrunk by about 40 percent.

That event, the Palaeocene-Eocene Thermal Maximum, happened over a longer time than the current global warming.

The speed of modern climate change could mean, "organisms may not respond or adapt quickly enough", especially those with long generation times.

 by "environment clean generations"