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[阅读小分队] 【每日阅读训练第四期——速度越障12系列】【12-6】科技

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发表于 2012-12-26 14:16:14 | 显示全部楼层 |阅读模式
【速度一】

How Excess Holiday Eating Disturbs Your 'Food Clock'

Dec. 21, 2012 — If the sinful excess of holiday eating sends your system into butter-slathered, brandy-soaked overload, you are not alone: People who are jet-lagged, people who work graveyard shifts and plain-old late-night snackers know just how you feel.
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All these activities upset the body's "food clock," a collection of interacting genes and molecules known technically as the food-entrainable oscillator, which keeps the human body on a metabolic even keel. A new study by researchers at the University of California, San Francisco (UCSF) is helping to reveal how this clock works on a molecular level.
Published this month in the journal Proceedings of the National Academy of Sciences, the UCSF team has shown that a protein called PKCγ is critical in resetting the food clock if our eating habits change.
The study showed that normal laboratory mice given food only during their regular sleeping hours will adjust their food clock over time and begin to wake up from their slumber, and run around in anticipation of their new mealtime. But mice lacking the PKCγ gene are not able to respond to changes in their meal time -- instead sleeping right through it.
The work has implications for understanding the molecular basis of diabetes, obesity and other metabolic syndromes because a desynchronized food clock may serve as part of the pathology underlying these disorders, said Louis Ptacek, MD, the John C. Coleman Distinguished Professor of Neurology at UCSF and a Howard Hughes Medical Institute Investigator.
It may also help explain why night owls are more likely to be obese than morning larks, Ptacek said.
"Understanding the molecular mechanism of how eating at the "wrong" time of the day desynchronizes the clocks in our body can facilitate the development of better treatments for disorders associated with night-eating syndrome, shift work and jet lag," he added.
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【速度二】

Resetting the Food Clock
Look behind the face of a mechanical clock and you will see a dizzying array of cogs, flywheels, reciprocating counterbalances and other moving parts. Biological clocks are equally complex, composed of multiple interacting genes that turn on or off in an orchestrated way to keep time during the day.
In most organisms, biological clockworks are governed by a master clock, referred to as the "circadian oscillator," which keeps track of time and coordinates our biological processes with the rhythm of a 24-hour cycle of day and night.
Life forms as diverse as humans, mice and mustard greens all possess such master clocks. And in the last decade or so, scientists have uncovered many of their inner workings, uncovering many of the genes whose cycles are tied to the clock and discovering how in mammals it is controlled by a tiny spot in the brain known as the "superchiasmatic nucleus."
Scientists also know that in addition to the master clock, our bodies have other clocks operating in parallel throughout the day. One of these is the food clock, which is not tied to one specific spot in the brain but rather multiple sites throughout the body.
The food clock is there to help our bodies make the most of our nutritional intake. It controls genes that help in everything from the absorption of nutrients in our digestive tract to their dispersal through the bloodstream, and it is designed to anticipate our eating patterns. Even before we eat a meal, our bodies begin to turn on some of these genes and turn off others, preparing for the burst of sustenance -- which is why we feel the pangs of hunger just as the lunch hour arrives.
Scientist have known that the food clock can be reset over time if an organism changes its eating patterns, eating to excess or at odd times, since the timing of the food clock is pegged to feeding during the prime foraging and hunting hours in the day. But until now, very little was known about how the food clock works on a genetic level.
What Ptacek and his colleagues discovered is the molecular basis for this phenomenon: the PKCγ protein binds to another molecule called BMAL and stabilizes it, which shifts the clock in time.
The article, "KCγ participates in food entrainment by regulating BMAL1" is authored by Luoying Zhang, Diya Abrahama, Shu-Ting Lin, Henrik Oster, Gregor Eichele, Ying-Hui Fu, and Louis J. Ptácek and appears in the Proceedings of the National Academy of Sciences.
In addition to UCSF, authors on the study are affiliated with the Max Planck Institute of Biophysical Chemistry in Göttingen, Germany.
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【速度三】

Study Shows Rapid Warming On the West Antarctic Ice Sheet

Dec. 23, 2012 — In a discovery that raises further concerns about the future contribution of Antarctica to sea level rise, a new study finds that the western part of the ice sheet is experiencing nearly twice as much warming as previously thought.
[attachimg=450,345]112182[/attachimg]

The temperature record from Byrd Station, a scientific outpost in the center of the West Antarctic Ice Sheet (WAIS), demonstrates a marked increase of 4.3 degrees Fahrenheit (2.4 degrees Celsius) in average annual temperature since 1958 -- that is, three times faster than the average temperature rise around the globe.
This temperature increase is nearly double what previous research has suggested, and reveals -- for the first time -- warming trends during the summer months of the Southern Hemisphere (December through February), said David Bromwich, professor of geography at Ohio State University and senior research scientist at the Byrd Polar Research Center.
The findings were published online this week in the journal Nature Geoscience.
"Our record suggests that continued summer warming in West Antarctica could upset the surface mass balance of the ice sheet, so that the region could make an even bigger contribution to sea level rise than it already does," said Bromwich.
"Even without generating significant mass loss directly, surface melting on the WAIS could contribute to sea level indirectly, by weakening the West Antarctic ice shelves that restrain the region's natural ice flow into the ocean."
Andrew Monaghan, study co-author and scientist at the National Center for Atmospheric Research (NCAR), said that these findings place West Antarctica among the fastest-warming regions on Earth.
"We've already seen enhanced surface melting contribute to the breakup of the Antarctic's Larsen B Ice Shelf, where glaciers at the edge discharged massive sections of ice into the ocean that contributed to sea level rise," Monaghan said. "The stakes would be much higher if a similar event occurred to an ice shelf restraining one of the enormous WAIS glaciers."
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【速度四】

Researchers consider the WAIS especially sensitive to climate change, explained Ohio State University doctoral student Julien Nicolas. Since the base of the ice sheet rests below sea level, it is vulnerable to direct contact with warm ocean water. Its melting currently contributes 0.3 mm to sea level rise each year -- second to Greenland, whose contribution to sea level rise has been estimated as high as 0.7 mm per year.
Due to its location some 700 miles from the South Pole and near the center of the WAIS, Byrd Station is an important indicator of climate change throughout the region.
In the past, researchers haven't been able to make much use of the Byrd Station measurements because the data was incomplete; nearly one third of the temperature observations were missing for the time period of the study. Since its establishment in 1957, the station hasn't always been occupied. A year-round automated station was installed in 1980, but it has experienced frequent power outages, especially during the long polar night, when its solar panels can't recharge.
Bromwich and two of his graduate students, along with colleagues from NCAR and the University of Wisconsin-Madison, corrected the past Byrd temperature measurements and used corrected data from a computer atmospheric model and a numerical analysis method to fill in the missing observations.
Aside from offering a more complete picture of warming in West Antarctica, the study suggests that if this warming trend continues, melting will become more extensive in the region in the future, Bromwich said.
While the researchers work to fully understand the cause of the summer warming at Byrd Station, the next step is clear, he added.
"West Antarctica is one of the most rapidly changing regions on Earth, but it is also one of the least known," he said. "Our study underscores the need for a reliable network of meteorological observations throughout West Antarctica, so that we can know what is happening -- and why -- with more certainty."
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【速度五】

Origin of Life: Hypothesis Traces First Protocells Back to Emergence of Cell Membrane Bioenergetics

Dec. 20, 2012 — A coherent pathway -- which starts from no more than rocks, water and carbon dioxide and leads to the emergence of the strange bio-energetic properties of living cells -- has been traced for the first time in a major hypothesis paper in Cell this week.
[attachimg=546,408]112184[/attachimg]

At the origin of life the first protocells must have needed a vast amount of energy to drive their metabolism and replication, as enzymes that catalyse very specific reactions were yet to evolve. Most energy flux must have simply dissipated without use.
So where did it all that energy come from on the early Earth, and how did it get focused into driving the organic chemistry required for life?
The answer lies in the chemistry of deep-sea hydrothermal vents. In their paper Nick Lane (UCL, Genetics, Evolution and Environment) and Bill Martin (University of Dusseldorf) address the question of where all this energy came from -- and why all life as we know it conserves energy in the peculiar form of ion gradients across membranes.
"Life is, in effect, a side-reaction of an energy-harnessing reaction. Living organisms require vast amounts of energy to go on living," said Nick Lane.
Humans consume more than a kilogram (more than 700 litres) of oxygen every day, exhaling it as carbon dioxide. The simplest cells, growing from the reaction of hydrogen with carbon dioxide, produce about 40 times as much waste product from their respiration as organic carbon (by mass). In all these cases, the energy derived from respiration is stored in the form of ion gradients over membranes.
This strange trait is as universal to life as the genetic code itself. Lane and Martin show that bacteria capable of growing on no more than hydrogen and carbon dioxide are remarkably similar in the details of their carbon and energy metabolism to the far-from-equilibrium chemistry occurring in a particular type of deep-sea hydrothermal vent, known as alkaline hydrothermal vents.
Based on measured values, they calculate that natural proton gradients, acting across thin semi-conducting iron-sulfur mineral walls, could have driven the assimilation of organic carbon, giving rise to protocells within the microporous labyrinth of these vents.
They go on to demonstrate that such protocells are limited by their own permeability, which ultimately forced them to transduce natural proton gradients into biochemical sodium gradients, at no net energetic cost, using a simple Na+/H+ transporter. Their hypothesis predicts a core set of proteins required for early energy conservation, and explains the puzzling promiscuity of respiratory proteins for both protons and sodium ions.
These considerations could also explain the deep divergence between bacteria and archaea (single celled microorganisms) . For the first time, says Lane, "It is possible to trace a coherent pathway leading from no more than rocks, water and carbon dioxide to the strange bioenergetic properties of all cells living today."
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【越障】

Chinese Medicine Yields Secrets: Atomic Mechanism of Two-Headed Molecule Derived from Chang Shan, a Traditional Chinese Herb

Dec. 23, 2012 — The mysterious inner workings of Chang Shan -- a Chinese herbal medicine used for thousands of years to treat fevers associated with malaria -- have been uncovered thanks to a high-resolution structure solved at The Scripps Research Institute (TSRI).
[attachimg=800,566]112183[/attachimg]

Described in the journal Nature this week, the structure shows in atomic detail how a two-headed compound derived from the active ingredient in Chang Shan works. Scientists have known that this compound, called halofuginone (a derivative of the febrifugine), can suppress parts of the immune system -- but nobody knew exactly how.
The new structure shows that, like a wrench in the works, halofuginone jams the gears of a molecular machine that carries out "aminoacylation," a crucial biological process that allows organisms to synthesize the proteins they need to live. Chang Shan, also known as Dichroa febrifuga Lour, probably helps with malarial fevers because traces of a halofuginone-like chemical in the herb interfere with this same process in malaria parasites, killing them in an infected person's bloodstream.
"Our new results solved a mystery that has puzzled people about the mechanism of action of a medicine that has been used to treat fever from a malaria infection going back probably 2,000 years or more," said Paul Schimmel, PhD, the Ernest and Jean Hahn Professor and Chair of Molecular Biology and Chemistry and member of The Skaggs Institute for Chemical Biology at TSRI. Schimmel led the research with TSRI postdoctoral fellow Huihao Zhou, PhD.
Halofuginone has been in clinical trials for cancer, but the high-resolution picture of the molecule suggests it has a modularity that would make it useful as a template to create new drugs for numerous other diseases.
The Process of Aminoacylation and its Importance to Life
Aminoacylation is a crucial step in the synthesis of proteins, the end products of gene expression. When genes are expressed, their DNA sequence is first read and transcribed into RNA, a similar molecule. The RNA is then translated into proteins, which are chemically very different from DNA and RNA but are composed of chains of amino acid molecules strung together in the order called for in the DNA.
Necessary for this translation process are a set of molecules known as transfer RNAs (tRNAs), which shuttle amino acids to the growing protein chain where they are added like pearls on a string. But before the tRNAs can move the pearls in place, they must first grab hold of them.
Aminoacylation is the biological process whereby the amino acid's pearls are attached to these tRNA shuttles. A class of enzymes known as aminoacyl-tRNA synthetases is responsible for attaching the amino acids to the tRNAs, and Schimmel and his colleagues have been examining the molecular details of this process for years. Their work has given scientists insight into everything from early evolution to possible targets for future drug development.
Over time what has emerged as the picture of this process basically involves three molecular players: a tRNA, an amino acid and the aminoacyl-tRNA synthetase enzyme that brings them together. A fourth molecule called ATP is a microscopic form of fuel that gets consumed in the process.
The new work shows that halofuginone gets its potency by interfering with the tRNA synthetase enzyme that attaches the amino acid proline to the appropriate tRNA. It does this by blocking the active site of the enzyme where both the tRNA and the amino acid come together, with each half of the halofuginone blocking one side or the other.
Interestingly, said Schimmel, ATP is also needed for the halofuginone to bind. Nothing like that has ever been seen in biochemistry before.
"This is a remarkable example where a substrate of an enzyme (ATP) captures an inhibitor of the same enzyme, so that you have an enzyme-substrate-inhibitor complex," said Schimmel.
The article, "ATP-Directed Capture of Bioactive Herbal-Based Medicine on Human tRNA Synthetase," by Huihao Zhou, Litao Sun, Xiang-Lei Yang and Paul Schimmel was published in the journal Nature on Dec. 23, 2012.
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发表于 2012-12-26 15:30:28 | 显示全部楼层
1'46

2'22
1'41
1'44
2'47
obstacle
3'56
发表于 2012-12-26 15:46:39 | 显示全部楼层
1'48
2'36
1'50 the warming trend in West Antarctic is faster than we thought, and the result is that the sea level will grow faster than the past.
1'55 the reason why WAIS is the most rapid warming reigon in the world and the strategy to this change.
2'59 没有看懂,好多生词……
4‘46 仍旧好多生词
  the mysterious mechanism of  two-headed molecule treating fever from malaria infection and the aminoacylation process.
发表于 2012-12-26 17:33:57 | 显示全部楼层
Time1: 122 words/min
There is a "food clock" wroking in human's body. This clock is reflected from our eating habits and could influence our body health and figure.

Time2: 142 words/min
In addition to the master clock,the food clock is there to help our bodies make the most of our nutritional intake. The food clock can be reset over time, but until now, very little was known about how the food clock works on a genetic level.

Time3: 159 words/min
The western part of the ice sheet is experiencing nearly twice as much warming as previously thought so that West Antarctica among the fastest-warming regions on Earth.

Time4: 149 words/min
West Antarctica is one of the most rapidly changing regions on Earth, but it is also one of the least known.

Time5: 128 words/min
It is possible to trace a coherent pathway leading from no more than rocks, water and carbon dioxide to the strange bioenergetic properties of all cells living today.

Obstacle:145 words/min
At begining, the article mainly introduce a finding about the process of a Chinese traditional herb working to the fever.
Then, introducing the study background and prespective in other dieases.
In the end, i think the article aims to point out the special role of something, but i cannot totally figure it out.
发表于 2012-12-26 21:59:27 | 显示全部楼层
1'50
2'21
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发表于 2012-12-27 10:54:07 | 显示全部楼层
1'36''
2'26''
1'53''
2'00''
3'26''

3'42''
发表于 2012-12-27 11:34:19 | 显示全部楼层
1'40"
1'55"
1'03"
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发表于 2012-12-27 11:55:05 | 显示全部楼层
好吧,继续补作业……

1'31
2'22
1'26
1'47
2'26

越障:
Main idea: A new finding about how the two-headed compound derived from Chang Shan works to cure fever related to malaria

Details about the finding:
>>eople have known that the compound(HaloXX) can suppress part of the immune system, but no one knew exactly how.
>>Chang Shan probably interfere the protein synthesis process( Aminoacylation) of malaria parasites and suceesfully kill them.
>>HaloXX has been used to deal with cancer, but the new finding makes it possible in creating new drugs for other diseases.

The process of Aminoacylation: an end product of gene expression
>>gene expressed→DNA→RNA→protein; tRNA needed for transpotation(复习高中生物的感觉……)
>>A class of enzymes catch amino acids and transfer them to tRNA→Aminoacylation; ATP is also needed but consumed during this process
>>scientists' work is to study the molecule details about the process
>>HaloXX works by blocking the enzymes and make them unactive where the tRNA and amino acid come together

这个回忆写得实在太挫以致我HHP吐槽双无能
发表于 2012-12-27 16:14:26 | 显示全部楼层
这啥时候的事,我怎么落下啦……
发表于 2012-12-29 07:21:06 | 显示全部楼层
1'39

Food clock is built on molecular basis.
then introduce the experiment on mice
food clock is closely related with obesity

2'50

There are different clocks, most of which related to master clock. Different animals has different master clock.
Food clock is related to many part of body for metabolism.
The mechanism of food clock
On molecular basis, PKCY stablize the food clock together with BMAL

1'53

Survey found that WAIS temp rise is three time fast than before
It could lead the surface ice melting that contributes a lot to sea level rising and weaken the ice shelves

1'55
WAIS contributes 0.3mm to sea level rise every year.
Since the data in byrd station is incomplete, scientists has to use some method to complete the data. They find thatthe if trend continue, melting will be extensive in that area.
Scientists require the reliable data on WAIS.

3'00
Discussing about where the energy come from for metabolism of the orgin of life
后面木有看懂 只能等晚上精读再看看了  考试遇到这种就伤不起了
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