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[阅读小分队] 【每日阅读训练第四期——速度越障16系列】【16-11】科技

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发表于 2013-3-26 09:15:53 | 显示全部楼层 |阅读模式

大米回来了,呵呵。

今天的作业。

大家加油哦!

文章标题我是用白色的字色,大家选择一下就能看到了。

Giant squid population is one big happy species
Elusive deep ocean dwellers have low genetic diversitydespite living around the globe

By Tina Hesman Saey                              
Time1

Giant squid are so mysterious — and so huge— that theyinspired the legend of the kraken, a Scandinavian sea monster. Now, a geneticanalysis adds to the creatures’ mystique.

DNA evidence suggests that all giant squid are part ofone global interbreeding species instead of the three that scientistspreviously thought existed, an international group of scientists reports March20 in the Proceedings of the Royal Society B. The finding indicates the giantsquid must migrate long distances to keep the breeding population well mixed.
The

massive invertebrates also have some of the lowestgenetic diversity of any species, the researchers report. That finding and thesquid’s global interbreeding are nearly impossible for scientists to explain,says study coauthor M. Thomas Gilbert, a geneticist at the Natural HistoryMuseum of Denmark in Copenhagen. “We were very surprised by the results,”Gilbert says.

Most of what is known about giant squid comes fromstudying carcasses washed up on beaches, hauled in by fishermen or found in thebellies of sperm whales, the giant squid’s natural predator. Only last year didan expedition film a giant squid in its natural habitat. Researchers candescribe the physical characteristics of the animals, which can grow to beabout 18 meters long with parrotlike beaks, sucker-studded tentacles and eyesbigger than a person’s head. But not much is known about how the creatureslive.

Gilbert and his team got a glimpse by examiningmitochondrial DNA from 43 giant squid. Mitochondria are the energy factoriesinside cells. Scientists can trace a species’ life history through the DNAcarried in mitochondria.

Researchers had thought there were three species of giantsquid: one in the North Atlantic, a second in the southern oceans and a thirdsmaller species in Japanese waters, says Clyde Roper, a marine biologistemeritus at the Smithsonian Institution’s Museum of Natural History inWashington, D.C. But the new analysis puts squid worldwide into what wasthought to be the Atlantic Ocean-dwelling species, Architeuthis dux.

330

Time2
The genetic homogeneity suggests that somehow squid musttravel long distances. A previous chemical analysis of the giant squid’s sharpbeaks indicated that adults don’t migrate far. That means the juveniles andlarvae must leave local waters and migrate around the world. Gilbert and hiscolleagues think “the young float around on the surface before they dive deepand become kingpins.” Surface currents could disperse the youngsters far andwide.

Roper calls the idea reasonable but notes that scientistshave spotted only few young squid in the ocean’s upper reaches.

Generally, low diversity comes with small populations,but researchers think the giant squid population is huge, perhaps in thehundreds of millions. They only seem rare because they live in the deep sea,Roper says. “We don’t go where they go very often, and they don’t go where we go.”

Gilbert and his colleagues suggest that giant squid usedto be rare but had a population explosion between 32,000 years and 730,000years ago. The date spread is large because scientists don’t know how longgiant squid take to reproduce or how frequently their DNA mutates.

Alternatively, the giant squid population might have beenlarge in the past, but rapidly diminished — what scientists call a populationbottleneck — and then grew again. “How can you bottleneck a species that livesglobally?” Gilbert asks. “It’s a massive mystery.”

The researchers have found no trace of historicalenvironmental conditions that might have caused a global bottleneck or rapidpopulation expansion. Whaling may have dramatically reduced the number of spermwhales and enabled a giant squid boom. But whaling is far too recent to accountfor population growth starting 32,000 or more years ago. “It’s sort of ahead-scratching thing,” Roper says of the population puzzle.

Gilbert says he hasn’t given up on the whaling hypothesis,but hopes that another solution may present itself. “What we’re really hopingis that somebody will read our paper and tell us, ‘You guys are crazy. This isthe real answer.’”

333                              
asmanian devil disease reveals its secrets

Deadly cancer turns off genes, evading the immune system
By Tina Hesman Saey
                              

Time3
A contagious cancer decimating Tasmanian devils makesitself invisible to the animals’ immune systems, which might otherwise fight itoff, a new study shows.

Devil facial tumor disease shuts down production ofproteins that normally decorate the surface of cells, telling the body whethera cell is its own or not. As a result, the devil’s immune system doesn’trecognize cancer cells from another devil as a potentially worrisome invader,Hannah Siddle, a marsupial geneticist at the University of Cambridge and aninternational group of collaborators report online March 11 in the Proceedingsof the National Academy of Sciences.

The finding could lead to a way to stop the deadlydisease. “It’s really the first hope that there could be a vaccine or immunetherapy,” says Elizabeth Murchison of the Wellcome Trust Sanger Institute andthe University of Cambridge. Murchison, who was not involved in the new study,discovered in 2009 that the tumor originated in cells insulating a singledevil’s nerve fibers. Since that initial case, which probably occurred in thelate 1980s or early 1990s, the disease has spread across eastern and centralparts of Tasmania, killing every devil it infects.

Tasmanian devils have such low levels of geneticdiversity that many researchers thought the animals’ immune systems couldn’tdistinguish their own cells from other devils’, and wouldn’t recognize a tumorcell as foreign. Yet the marsupials aren’t exactly identical, Siddle says.Other studies have demonstrated that the animals reject skin grafts from oneanother, suggesting that the tumor cells should get the boot, too. But thedevils don’t appear to mount any serious defense against the cancer.
271

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 楼主| 发表于 2013-3-26 09:17:05 | 显示全部楼层
【Time4】

Siddle and her colleagues discovered that devil facial tumor cells turn off genes that the immune system uses to distinguish between cells from its own body and foreign cells. Without the proteins made by these major histocompatibility, or MHC, genes, the tumor cell can conceal its true identity as both a cancer cell and tissue from another animal.

In tests of devil tumor cells done in lab dishes, the researchers were able to turn MHC genes back on with a dose of either an antifungal drug called Trichostatin A or an immune chemical called interferon gamma. Trichostatin A is known to affect gene activity. Dogs infected with a contagious cancer called canine transmissible venereal tumor keep the nonfatal cancer in check partly by making interferon gamma.

If the drug or the immune chemical works the same way in the animals as it did in cells, it could rev up the devil’s immune system to fight off the tumor, says study coauthor Jim Kaufman, an immunogeneticist at the University of Cambridge.

Tumor cells that have had their MHC genes turned back on might serve as vaccines. (The tumor cells would be killed before scientists injected them into the devils.) But other researchers aren’t so sure such a vaccine will work. Many tumors, including the contagious tumor that infects dogs, turn down production of MHC proteins. Yet immune cells still find and at least attempt to kill the cancers, unlike in the devils.

The devil facial tumor must take additional steps such as secreting chemicals to tamp down immune responses, says Robin Weiss, a virologist at University College London. To fight the devils’ disease, researchers will need to discover any other evasion strategies the tumor uses.

Siddle and Kaufman are already on the trail of the tumor’s other strategies and are working with collaborators in Tasmania to test a vaccine using cells with rebooted MHC genes.

【314】

【Time5】
Christopher Wright and Michael Wimberly of South Dakota State University published a study in the March 5, 2013 edition of the Proceedings of the National Academy of Sciences (PNAS), showing that grasslands in what is called the western corn belt of the United States are being increasingly converted to farm for corn and soybeans. The likely cause is the demand for biofuels, which has been driving the prices of these crops to an all-time high. Wright and Wimberly focused on the U.S. states of North Dakota, South Dakota, Nebraska, Minnesota and Iowa. By using newly available data on crop cover from the U.S. Department of Agriculture (USDA), they demonstrated that the rate of land use change to corn and soy has not been this high since the 1920s and 30s, and is comparable to deforestation rates in Brazil and Indonesia in the 1980s.


Since most high-quality farmland is already being used to grow corn and soybeans, farmers wanting to take advantage of the corn/soy price boom caused by biofuel demand are converting poorer quality land that is at a high risk for erosion, and is more susceptible to drought. Grassland soils also store vast amounts of carbon, and disturbing these soils by farming them causes massive carbon flux to the atmosphere. Furthermore, many previously unfarmed grasslands are near wetlands, and agricultural runoff in the form of inefficiently used fertilizers can contaminate those ecosystems and harm waterfowl.

While Wright and Wimberly suggest corn and soy based biofuel demand is responsible for changing grasslands, they also acknowledge that different crops such as perennial grasses may be more beneficial for carbon savings and pollution reduction. However, since land use change has been so aggressive, a window of opportunity to move toward biofuel solutions other than corn could be closing.

Bottom line: Increased corn and soy prices, partially driven by demand for biofuels, are encouraging farmers to intensify agriculture in grasslands, with negative environmental results on climate, grassland biodiversity and wetlands
【327】

 楼主| 发表于 2013-3-26 09:17:23 | 显示全部楼层
Obstacle

IAU changes its mind again on giving names to exoplanets


Exoplanet discovery has been big business in recent years. There are 861 known exoplanets – planets orbiting distant stars – as of March 25, 2013 according to exoplanet.eu. Some astronomers estimate that our Milky Way galaxy might contain a 100 billion expoplanets. Meanwhile, the IAU – the international body of astronomers that, since its inaugural meeting in 1922, has taken upon itself the responsibility for standardizing, designating and naming space objects, has waffled about whether it will give proper names to planets orbiting other suns.

Today (March 25, 2013), I noticed the IAU has changed its mind again, since just last week. Since other groups of astronomers have recently used a system of popular voting to suggest names for space objects, showing the awesome power of crowdsourcing, I suspect the IAU may be feeling the heat to democratize the naming of space objects in general, and exoplanets in particular.

Here are some facts. In 2006, an IAU committee voted to demote Pluto from full planet status. That was an extremely unpopular decision among many members of the general public (and among some astronomers). Even today, if you mention Pluto’s loss of full planet status on a social media page such as EarthSky’s Facebook page, you’ll receive back an outpouring of emotion.

In 2009, the IAU says a committee of its Commission 53 Extrasolar Planets discussed the possibility of giving popular names to exoplanets in addition to their existing catalogue designations (for example, Alpha Centauri Bb). No consensus was reached, but the majority on the committee of astronomers who discussed the idea was not in favour of this possibility at that time. That remained true as late as last week, when I happened to check the IAU’s exoplanet page while writing about Uwingu’s campaign to name Alpha Centauri Bb. On March 21, 2013, on its website, the IAU said it was developing:
… a system for clear and unambiguous scientific designation of [exoplanets] at all stages during their study, from tentative identification to fully-characterized objects …

On March 21, IAU also said on its website:
In response to frequent questions about plans to assign actual names to extra-solar planets, the IAU sees no need and has no plan to assign names to these objects at the present stage of our knowledge. Indeed, if planets are found to occur very frequently in the universe, a system of individual names for planets might well rapidly be found equally impracticable as it is for stars, as planet discoveries progress.

However, today (March 25, 2013), the same link at the IAU’s website says this:
… considering the ever increasing interest of the general public in being involved in the discovery and understanding of the universe, the IAU decided in 2013 to restart the discussion of the naming procedure for exoplanets and asses the need to have popular names as well. In 2013 the members of Commission 53 will be consulted in this respect and the result of this will be made public on this page.

What changed the IAU’s mind? In late February 2013, the SETI Institute in Mountain View, California, conducted a contest to suggest names for newly discovered moons of Pluto. Now, Pluto’s newest moon might be called Vulcan, a name suggested by actor William Shatner, who played Captain Kirk in the original Star Trek TV series, following an online campaign by the show’s fans. Vulcan received nearly 200,000 votes among the 450,000 cast during a two-week contest. The second recently-discovered moon will be called Cerberus, after the three-headed dog that guarded the gates of the underworld, which received 100,000 votes. In media reports, it’s said the SETI Institute is now waiting for IAU approval of these names.


Then, earlier this month, the space company Uwingu announced another people’s choice competition for naming the newly found planet orbiting Alpha Centauri B. When asked for a comment on the IAU’s change of mind this morning, Uwingu CEO – planetary scientist and former NASA science boss Dr. Alan Stern – told EarthSky:
I’m encouraged. I just hope the IAU recognizes that in this 21st century world of Internets, social networks, and flattened, more democratized publishing, that the members of the IAU – who are small in number – have no greater authority than what large numbers of people think.

When asked why Uwingu was organizing its efforts as a vote to name Alpha Centauri Bb, Stern also said:
Why do we believe it’s time to democratize? First, there’s no reason not to. It increases public interest in astronomy by personally involving people. It’s a great way to increase interest in schools too, and we just can’t find any good reason for elite, behind-closed-doors committees to appoint themselves any longer to be the gatekeepers on astronomical names.

By the way, Stern also said that examples of suggested names so far for Alpha Centauri Bb are “all over the map” and include names of politicians, scifi heros, Greek gods, personal/family names, sports teams.
【819】





发表于 2013-3-26 10:27:44 | 显示全部楼层
占座抢沙发啦啦啦~
==========================================================
1 - 01:45
Recently, scientists have studied the giant squid by exploring DNA evidence. And what they have found is different from what they previously thought.

2 - 02:03
The giant squid is low in genetic diversity but is huge in population. This situation is strange because generally low genetic diversity leads to small population. Scientists guessed that there may be a bottleneck. But they themselves are not so convinced. And they hoped that one day in the future, someone can point out the real answer.

3 - 01:34
A kind of tumor can hide itself from the immune system. ...The study leads to a way to cure cancer.

4 - 01:35
The researchers found out how the tumor avoids the inspection of the immune system. They also carried out an experiment on dogs.

5 - 01:49
In some states in the US, large area of land is converted to growing corn and soy beans, because high demand of the crops (due to the need for biofuels) has driven the price high. It is report that the area is the largest in the past decades. While these plants can help prevent the soil from erosion (because they absorb carbon), they are also responsible for bad climate change.

obstacle - 04:12
The astronomy-related academic association IAU recently democratize the authority to name planets. The passage quotes several examples as evidence. This act of IAU is quite opposite to its former claims. IAU now holds that getting more people involved in the astonomical issues can have multiple benefits, such as inspiring interest among the public.

做速度的时候感觉还是不够好,有些东西记不住,而且看到生物上奇奇怪怪的各种名词 大脑就转不动了TT,这个毛病要克服!
&我发现,科技文的可怕之处对我来说,不仅仅在文章本身……还有……生动形象的图片TT
发表于 2013-3-26 11:55:31 | 显示全部楼层
1'55''
1'58''
1'30''
1'40''
1'45''

4'10''
发表于 2013-3-26 13:00:39 | 显示全部楼层
2‘18
"reserch found a giant Q;
they trace its source by DNA;
it should be atlan ocean"
2'23
"Adult Q travel long;
They have large population
but scients donnot know why"
1'54
immune system
2'07
tumor cell turn off the gene
3'27
land turns into farm because demand booms;
5'39
"There are more founding in exoplanet discovery
and people has more intrest in naming
and ICA changing its mind"
发表于 2013-3-26 16:53:44 | 显示全部楼层
欢迎大米回归~~~
第一篇文章读过了
ps:文章有点粘连的情况...而且新版的论坛的字怎么看上去都是灰色的= = 是我的电脑的问题吗

0:01:40
0:01:56
0:01:57

0:04:05
发表于 2013-3-26 17:19:20 | 显示全部楼层
1-2'19
the giant are studied by the scientsits and have 3 species.

2-1'49
we can hardly see giantsquid because they usually dives in deep sea and only those young swims on the surface of the water, there are still alot of unknown speices under the water

3-1'25
there is some hope that the cancer can be cured by vaccine through immune therapy

4-1'50
scientists are collaborating on making a vaccine for devils, maybe oneday it can be use to human to cure cancer

5-1'43
since the biofuel is in high demand, the farmers prefer to plant corn and soy for biofuel, but they are at risk, because these plants are easy to be eroded.

obstacle
4'33
IAU used to name the exoplanets found by astronauts, now it gives the rights to the public, since it used unpopular name for some planet, many people thinks it's the time to give the public the rights

逻辑链:IAU以前一直要给行星命名,最近他改主意了,因为之前命名失误引起了公愤,所以最近他发布了两则声明决定把命名权让给群众,大家都很支持,并且认为应该把这种权利适用于更多方面
发表于 2013-3-26 17:26:48 | 显示全部楼层
一直在站位。。。。。。。有些做了没发上来。。。。。。晚上睡觉前补4次作业。。。。。。


补作业4


1-330-1'39        introduce the giant

2-333-1'40        more information about giant by s a scientist

3-271-1'30       

4-314-1'46

5-327-1'52

6-819-4'26        name the planet..
发表于 2013-3-26 18:54:56 | 显示全部楼层
科技文好弱哦……
1-330-2:12
Huge squid are found along the beach. Researchers try to find the species' life history through the DNA study.
2-333-2:10
Genetic suggest that squid travel long distances.The scientists think squid used to have a huge populations according to the species diversity
3-271-1:49
The DFT fight the body by misleading the immune system of animals.
4-314-2:10
The research of vaccines for killing devils are going on.
5-327-2:17
It brings harmful impact for climate that grassland have been changed to corn and soybeans
obstacle-819-5:09
More and more exoplanets are found.
IAU chage the way of naming space objects for twice.
It is democratic to give the naming right to public by voting
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