Behavior & experience shape neurogenesis


When a group of genetically identical mice lived in the same complex enclosure for 3 months, individuals that explored the environment more grew more new neurons than less adventurous mice, according to a study published on May 9 in Science. This link between exploratory behavior and adult neurogenesis shows that brain plasticity can be shaped by experience and suggests that the process may promote individuality, even among genetically identical organisms.

Scientists have often tried to tackle the question of how individual differences in behavior and personality develop in terms of the interactions between genes and environment. “But there is next to nothing [known] about the neurobiological mechanisms underlying individuality,” said Gerd Kempermann of the German Center for Neurodegenerative Diseases in Dresden.

One logical way to study this phenomenon is to look at how the brain’s structure and function change over time. Plasticity is hard to study because it mostly takes place at the synaptic level, so Kempermann and his colleagues chose to look at the growth of new neurons in the adult hippocampus. Earlier studies have demonstrated that both physical and cognitive activity increases adult neurogenesis in genetically identical mice, but there were differences between individuals in the amount of neuron growth.

To understand more, Kempermann and his colleagues housed 40 genetically identical female inbred mice in a complex 5-square-meter, 5-level enclosure filled with all kinds of objects designed to encourage activity and exploration. The mice were tagged with radio-frequency infer-red transponders which tracked their every movement. After 3 months, the researchers assessed adult neurogenesis in the mice by counting proliferating precursor cells, which had been labeled before the study began.

The researchers found that individual differences in exploratory behavior correlated with individual differences in the numbers of new neurons generated. “To our knowledge, it’s the first example of a direct link between individual behavior and brain plasticity,” Kempermann said.

The findings could help explain why human identical twins raised in the same family end up with different personalities.

One caution, though: although the mice in the study were genetically identical, it may be that they were not behaviorally identical to begin with: some variation may have occurred at a very early stage that made individuals more or less likely to explore.

The research provides a novel approach to studying the role of the environment in shaping personalities. “We’ve come up with an animal model to help address the ways living our lives make us who we are,” said Kempermann. “So we have touched on an approach that allows us start to get the small part of an answer to a very big question.”

J. Freund et al., “Emergence of individuality in genetically identical mice,” Science, 340:756-59, 2013.

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Alternative Crops for Drylands, by Scott O’Bar

I haven’t read this yet; just noticed it, but on the book’s website are some useful links, and a great collection of free PDF downloads!

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Lightest Material on Earth


carbon-aerogel
Multifunctional, Ultra‐Flyweight, Synergistically Assembled Carbon Aerogels | ReadCube Articles.

At Zhejiang University in China, Gao Chao, the lead scientist in creating this material, says it is made with one-atom-thick sheets and fibers of carbon, so Chao and his colleagues have dubbed it a carbon aerogel.  Check out the pics in the article-it’s amazing!

It’s still in its earliest stages of development, but in the future, the new material could be designed to soak up oil spills or clean other pollutants.  The materials used now to clean up spills absorb 10 times their weight in oil, but the new stuff can handle 900 times its weight in oil. And it absorbs quickly, Chao said, with each gram of material sucking up 69 grams of oil a second.

The material has a density of 0.16 milligrams per cubic centimeter, or about one-sixth the density of air, so, tell me, why is it not floating away instead of being perched on the flower stamens???

aero-carbon

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Microbes affect Weight Loss!


Surgically bypassing the stomach is not the only reason that patients this surgery quickly begin to drop pounds. Changes to the microbial make-up of their intestines also play a big role, according to a paper published in Science Translational Medicine yesterday (March 27):  A.P. Liou et al., “Conserved shifts in the gut microbiota due to gastric bypass reduce host weight and adiposity,” Sci. Transl. Med. 5, 178ra4, 2013.

Gastric bypass surgery was originally thought to work by forcibly reducing a person’s capacity for food, but the effects are more complicated than they first seemed, Lee Kaplan director of the Massachusetts General Hospital Weight Center in Boston and a senior author of the study explained. “We began to see, in patients that got bypass surgery, that they were not hungry and that they were not craving what they used to crave.”

It is known that patients having gastric bypass surgery also have altered gut microbial profiles. Kaplan and his team have now observed similar bypass-induced microbial changes in obese mice. Within 1 week of surgery, three phyla of microbes were significantly enriched in the mice. The mice lost 30 percent of their body weight, and exhibited metabolic changes—their blood glucose levels lowered and insulin sensitivity improved.

To determine if these microbial and metabolic changes shared a causal relationship, Kaplan’s team transplanted the microbial community from the guts of these mice into microbe-free, normal-weight mice.

“What we saw in the normal-weight recipients that were given gastric bypass microbiota was that their food intake was not altered, but they had less body fat and they lost about 5 percent of their body weight,” said lead author Alice Liou, a research scientist at Massachusetts General Hospital.

It is not yet clear whether such microbial transfers would be effective in humans, but the results imply that a probiotic that replicates the effect of gastric bypass surgery is possible, and may contribute to weight loss. Wouldn’t it be wonderful if medicine could identify supplements to achieve the same effects as a bypass, but without the risk of surgery?!

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Brain Activity Breaks DNA


E. Suberbielle et al., “Physiologic neuron activity causes DNA double-strand breaks in neurons, with exacerbation by amyloid-ß,” Nature Neuroscience, doi:10.1038/nn3356, 2013.
Double-stranded breaks in DNA—generally thought to be a severe form of damage—may simply be all in a day’s work for neurons, according to research published yesterday (March 24) in Nature Neuroscience. Scientists studying mice reported that normal neuronal activation stimulated by exposure to new environments can cause temporary DNA breaks—suggesting that transient damage may be involved in learning and memory.
Neurologist Lennart Mucke at the Gladstone Institutes and the University of California, San Francisco, whose lab is currently focusing on this question, acknowledged that it’s not yet clear what function, if any, these DNA breaks serve. Given that neuronal activation leads to changes in gene expression that enable animals to learn and form memories, it’s possible that the double-stranded DNA breaks enable these changes in some way.

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What I see out my window…


tree outside lab…at the lab

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Scientists Have 3D-Printed Embryonic Stem Cells


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