ChaseDream
搜索
查看: 561|回复: 22

[阅读小分队] 【Native Speaker每日训练计划】No.2783科技

[复制链接]
发表于 2020-5-18 17:18:09 | 显示全部楼层 |阅读模式
内容:Chopin Hong 编辑:Carrie Qin
Wechat ID: NativeStudy  / Weibo: http://weibo.com/u/3476904471
官方活动帖:长难句讨论帖-每日训练   SC讨论帖   CR讨论帖   RC讨论帖  Quant 讨论帖

Part I: Speaker

Barn Owl Babies Can Be Helpful Hatch Mates
By Jason G. Goldman on May 14, 2020

Food sharing is mainly found in adult animals as a part of social bonding. But in a rarely observed behavior in birds, older barn owl chicks will share food with younger ones.

Source: Scientific American
https://www.scientificamerican.com/podcast/episode/barn-owl-babies-can-be-helpful-hatch-mates/

[Rephrase 1, 03:05]


Part II: Speed



Malaria parasites may have their own circadian rhythms
By Jake Buehler
MAY 14, 2020

[Time 2]
The parasites that cause malaria may march to the beat of their own drum.

New genetic analyses suggest that Plasmodium parasites possess their own circadian rhythms, and don’t depend on a host for an internal clock, researchers report May 15 in Science. Figuring out how Plasmodium’s clock ticks may lead to ways to disrupt it, potentially adding to the growing arsenal of treatments for malaria. In 2018, the mosquito-borne illness sickened an estimated 228 million people worldwide and caused more than 400,000 deaths.

A malarial infection is a series of cyclical symptoms. Depending on the Plasmodium species involved, fever and chills return roughly every 24, 48 or 72 hours, thanks to the parasites’ synchronized reproduction within and destruction of a host’s red blood cells.

Researchers had long thought that the rhythmic nature of an infection was likely driven by a host’s circadian rhythms, says molecular parasitologist Filipa Rijo-Ferreira, a Howard Hughes Medical Institute associate at the University of Texas Southwestern Medical Center in Dallas. Circadian clocks help organisms anticipate regular, cyclic changes in their environment, like day and night cycles and daily fluctuations in temperature. These clocks are made up of genes and proteins that drive daily rhythms, such as the release of hormones, and typically operate on 24-hour cycles in many animals.

Rijo-Ferreira and colleagues recently showed that the Trypanosoma parasite behind the illness known as sleeping sickness has its own internal clock. So the team decided to look for a similar ability in Plasmodium.
[246 words]

[Time 3]
The scientists tracked rhythms of how genes were turned on and off in malaria parasites in infected mice hosts. The researchers put some mice in constant darkness, eliminating day and night cues and throwing off the animals’ circadian rhythms. But the timing of changes in the parasites’ gene activity levels in those mice was similar to that of mice exposed to regular day-night cycles.  

Next, to see if the parasites used a host’s feeding schedule to orient their clock, the team provided mice with food spread evenly throughout the day. But the Plasmodium in those mice kept the same internal rhythms as those in mice that were fed once daily.

And when the parasites were in hosts engineered to lack a clock entirely, the pathogens’ timekeeping ability ticked right along unhindered. These findings reveal that the light and feeding cues that set the hosts’ clocks don’t affect parasites’ rhythms, suggesting that the parasite has its own independent clock.

What’s more, in mutant mice genetically engineered to have a circadian clock slightly longer than 24 hours, the parasites attempted to synchronize their own clocks to that of their host’s, slowing their pace. While malaria parasites can parallel their host’s schedule, they don’t depend on their host for a clock, the team concludes, suggesting that the parasites use their own clocks to align with the host’s during an infection.

But while individual Plasmodium parasites appear to have an internal clock independent of a host’s, syncing up all the clocks in a population of parasites inside of a host does apparently require input from the host’s rhythms, the researchers say. In mice lacking an internal clock, the synchrony within an entire parasite population slowly decayed, falling apart after eight or nine days. This is similar to what happens to internal clocks in groups of mammalian cells without any external cues, such as sunlight or chemicals.
[312 words]

[Time 4]
“That is quite reassuring, because we really think that [Plasmodium’s clock] behaves just as another circadian system that we know very well,” Rijo-Ferreira says.

Rijo-Ferreira says she wasn’t surprised by the findings, given how many times internal clocks have independently evolved in nature in organisms ranging from bacteria to fungi to animals. “It’s almost unbelievable that an organism wouldn’t have a clock,” she says.

Further support for Plasmodium’s internal clock comes from a separate study, also in the May 15 Science, led by molecular biologist Steven Haase at Duke University. Haase and his team isolated a species of Plasmodium entirely from a host, growing four different strains of the parasite in the lab. They tracked the parasites’ patterns of gene activity levels too, finding that as much as 92.6 percent of the known genes for Plasmodium appear to be clock controlled, keeping time in the absence of a host.

Now that the existence of some kind of clock is confirmed, Haase says, the next steps are revealing its molecular underpinnings, and how the clock interacts with that of the host.

Uncovering “the components of the parasite’s timekeeping mechanism” could help determine if, in fact, the parasites have their own independently and consistently ticking clock, says Sarah Reece, an evolutionary parasitologist at the University of Edinburgh not involved with either study. While the findings suggest that some form of clock is at work here, “it’s still possible [the parasites] keep time in a simpler way,” she says, for instance reacting to some other external stimuli.   
[254 words]

Source: Science News
https://www.sciencenews.org/article/malaria-parasites-may-have-their-own-circadian-rhythms




Africa’s biggest collection of ancient human footprints has been found
By Bruce Bower
MAY 14, 2020

[Time 5]
More than 400 human footprints preserved in hardened volcanic sediment are providing a rare peek at social life among ancient East African hunter-gatherers.

These impressions, found in northern Tanzania near a village called Engare Sero, add up to the largest collection of ancient human footprints ever found in Africa, say evolutionary biologist Kevin Hatala of Chatham University in Pittsburgh and his colleagues.

People walked across a muddy layer of volcanic debris that dates to between around 19,100 and 5,760 years ago, the researchers report May 14 in Scientific Reports. Dating of a thin rock layer that partly overlaps footprint sediment narrows the age range for the footprints to between roughly 12,000 and 10,000 years ago, the team says.

Engare Sero lies in the vicinity of two much older hominid footprint sites — nearly 3.7-million-year-old Laetoli in Tanzania and 1.5-million-year-old Ileret in Kenya.

At Engare Sero, Hatala’s team analyzed foot impression sizes, distances between prints and which way prints pointed. One collection of tracks was made by a group of 17 people walking southwest across the landscape, the researchers found. Comparisons with modern human footprint measurements indicate that this group consisted of 14 women, two men and one young boy.

The women may have been foraging for food, while a few males visited or accompanied them, the researchers speculate. Some present-day hunter-gatherers, including Tanzania’s Hadza people, form largely female food-gathering groups.

In another set of six tracks, the footprints point northeast. Those tracks probably weren’t made by people traveling in a group. Instead, the impressions suggest that two women and a man had ambled along leisurely, a woman and a man had walked briskly, and another woman had run across the area, the researchers say.

Hatala’s new study is “a nice piece of work,” although it’s hard to specify what ancient Engare Sero people were doing based on their foot impressions, says geologist Matthew Bennett of Bournemouth University in Poole, England.

Many sets of footprint tracks — not just the one set of 17 tracks at Engare Sero — would be needed to argue convincingly that hunter-gatherers at that time formed female foraging groups, Bennett says. Even then, researchers wouldn’t know if such groups had been gathering plant foods or hunting prey.

Other footprint sites present especially promising opportunities for studying ancient human behavior, Bennett says. He is involved in ongoing work at White Sands National Park in New Mexico that has uncovered tens of thousands of footprints of humans, mammoths, giant sloths and other creatures from around 12,000 years ago. Early results suggest that humans hunted giant sloths, and Bennett expects that research there will yield many more insights into Stone Age hunting.
[440 words]

Source: Science News
https://www.sciencenews.org/article/africa-biggest-collection-ancient-human-footprints-found



Moisture, not light, explains why Munch’s ‘The Scream’ is deteriorating
By Maria Temming
MAY 15, 2020

[Time 6]

New insight into paint preservation could help “The Scream” show its face in public again.

Edvard Munch’s 1910 version of this iconic artwork has rarely been displayed since 2006 because the painting’s cadmium sulfide pigments are so fragile. Cadmium yellow brushstrokes in the sky and central figure have faded to off-white, and thick paint in the lake is flaking off. To prevent further decay, the Munch Museum in Oslo almost always keeps “The Scream” in storage, under carefully controlled lighting and about 50 percent humidity.

Now, a chemical analysis of the painting shows that moisture is the main reason for the deterioration, while light plays only a minor role, Letizia Monico, a chemist at the Italian National Research Council in Perugia, and her colleagues report online May 15 in Science Advances.

Researchers analyzed microscopic flakes of paint from “The Scream” along with paint samples with similar chemical composition that were artificially aged in the lab.  

X-ray probes of the paint samples revealed cadmium sulfate, a breakdown product of cadmium sulfide, in paint flecks from “The Scream.” Cadmium sulfate also showed up in artificially aged paints that were exposed to at least 95 percent humidity in both light and darkness, but similar samples exposed to light in 45 percent humidity didn’t show signs of decay. This suggests that moisture is the main culprit in aging “The Scream,” and that although the painting may be fine under normal lighting, it should be kept at 45 percent humidity or below.

This new understanding of the artwork may inform the preservation of other paintings by Munch’s contemporaries, such as Matisse and van Gogh, which also contain decaying cadmium sulfide pigments. But Monico cautions that every painting is a unique, complex chemical landscape, so conservation strategies must be devised on a case-by-case basis.
[298 words]

Source: Science News
https://www.sciencenews.org/article/star-orbiting-milky-way-giant-black-hole-confirms-einstein-was-right


Part III: Obstacle


Decades of Tree Data Reveal Forests Under Attack
By Max Kutner    |  SMITHSONIANMAG.COM  |  May 15, 2020

[Paraphrase 7]
The Blue Ridge Mountains make up one of the oldest mountain ranges in the world. They are also home to forests with diverse tree populations. But those trees are under attack from invasive species, and Smithsonian researchers say that the impact over time is becoming ever more concerning.

According to a study published in the journal Ecosystems on April 29, in a section of the Blue Ridge Mountains, about a quarter of the loss of tree biomass—roughly one-quarter of tree death—over the past three decades was linked to invasive species transported by humans. The study is believed to be the first long-term look at the impact of multiple invasive species on aspects of the forest, the researchers reported.

One of the forest sections they studied is part of the Smithsonian’s Forest Global Earth Observatory, or ForestGEO, a network of sites that monitors changes to forests. The initiative dates to 1980, when Smithsonian researchers began mapping, measuring and tagging trees at a site in Panama. That original plot contained a quarter of a million trees. “No one had ever tried anything like this ever before,” says Stuart Davies, director of ForestGEO.

The network now monitors some six million trees inside tropical and temperate forests at 70 sites in 27 countries. The methodology to monitor them is consistent across sites, which makes the program unique. “Unless you measure things in the same way, it’s very hard to compare them,” Davies says. “What we have is a very clearly standardized protocol, where we know if you compare a data set from Gabon with a data set from Brazil, there’s no question.” More than a thousand research articles have come out of the network.

For the new study, the researchers focused on plots inside Shenandoah National Park in Virginia, which contains a section of the Blue Ridge Mountains, and a nearby plot monitored by the Smithsonian Conservation Biology Institute. The team from the Smithsonian and the park looked at 67 plots of forest across 73 acres. The data was from 1987 to 2019 and contained more than 350,000 tree observations.

“We know that pests and pathogens can have a really important impact. But it’s highly variable in time and space,” says Kristina Anderson-Teixeira, a forest ecologist at SCBI and the Smithsonian Tropical Research Institute and lead author of the study. “I wanted to get a broader overall picture of, long-term, how have these been affecting the forests as a whole?”

The researchers found that the invasive species were tied to around 25 percent of tree deaths over the time period studied. “That’s pretty significant for the functioning of the forest,” Anderson-Teixeira says. “We’re losing cool species, species that we value for one reason or the other.” Normally trees have mortality rates of 1 or 2 percent per year, she says. For the trees that invasive species impacted, the figure was as high as 20 percent.

Changes to the forest affect the animals that live in them. This area is known for bobcats, raccoons, eastern striped skunks and opossums. “There are these cascading impacts of the forest composition on. . . the forest animals,” Anderson-Teixeira says. For example, the gypsy moth, an invasive insect, has devastated oak tree populations in the area, and animals such as American black bears, white-tailed deer, Allegheny woodrats, Eastern gray squirrels, and southern flying squirrels rely on acorns from those trees.

“Due to these invasive species,” says William McShea, a wildlife ecologist with the Conservation Ecology Center at SCBI and one of the study’s 20 authors, “you’re getting a lot more young trees, and that’s a much different forest composition. That benefits some species and doesn’t benefit others.” White-tailed deer flourish with young vegetation and woody plants at the forest floor, for example. But other species, including birds, prefer a more mature forest, according to McShea.

Invasive species aren’t just a problem in the Blue Ridge Mountains; they impact forests throughout the United States. People have documented at least 471 exotic insects and pathogens in forests across the country over the past few centuries, and similar situations exist in Europe and Asia.

The problem is species-specific, so particular invasive species impact particular tree hosts. The researchers identified eight combinations of invasive pests or pathogens and their hosts: American chestnuts suffered from chestnut blight, a fungus from Asia; elms had Dutch elm disease, also a fungus from Asia; redbuds had neofusioccum, a fungus of unknown origin; butternut trees had butternut canker, another fungus from Asia; dogwoods had dogwood anthracnose, yet another fungus from Asia; oaks attracted the gypsy moth, an insect from Europe; hemlocks were victim to hemlock woolly adelgid, an insect from Asia; and ash trees attracted the emerald ash borer, another insect from Asia.

Of the eight tree taxa they studied, seven have species that are now threatened or endangered because of the invasive pests or pathogens, according to the study. The researchers found six more combinations, but those trees declined possibly due to other factors.

Invasive species impact the trees through different means. For example, the emerald ash borer, an insect, gets under the bark and disrupts the xylem, a tissue that brings water and dissolved minerals from the roots to the leaves. Gypsy moths cause leaves to fall off trees.

Because of global trade and travel, invasive species will likely remain a problem. Climate change can make the problem worse, because unhealthy forests are less resistant to exotic species, and those pests and pathogens can spread faster under warmer conditions, according to Anderson-Teixeira.

Invasive species are among several ways that forests are under attack. Forest fires, such as those that burned in the Amazon rainforest in 2019 due to human deforestation, climate change and drought are additional ways. Even native species, such as white-tailed deer, which are in high density in certain parts of Shenandoah National Park, can disrupt the balance of the ecosystem if not regulated. As Anderson-Teixeira puts it, “There’s a lot of pressures on forests these days.”

These threats are evolving. Changes to land use are becoming increasingly worrisome to the forest monitors at ForestGEO. “We’re still losing something between 80 and 100,000 square kilometers of tropical rainforest every year,” says Davies, the ForestGEO director. This deforestation and fragmentation of forests allows other threats to increase, according to Davies. For example, hunting often happens when forests are more accessible to humans; fragmented forests are likely more susceptible to climate fluctuations; and when animals do not stay isolated in their forest habitats, they can transmit pathogens to humans, including coronaviruses.

But the researchers found that overall, the forest they studied remained healthy, even as trees impacted by invasive species died. That’s because forests are resilient.

The average above-ground biomass, a measure of trees above the soil, actually increased, as trees that were impacted less by the invasive pests and pathogens grew. Tree biodiversity also did not change much. “In some patches,” Anderson-Teixeira says, “you’d look around and see more species than you would have in the past. It works because it’s a fairly diverse forest, so you’re losing some species, and less affected species are filling in.”

The study suggests that people and governments prevent invasive species through policy regulations, biosecurity and conservation to make forests more resilient.

“People need to appreciate forests, recognize that our water, our clean air, so many services that we depend on, are the result of fully functioning, healthy forests,” Davies says. “Many people who are stuck at home at the moment are probably starting to realize, ‘Heck, I didn’t realize how much I really appreciate being outside and walking in the park.”
[1265 words]

Source: Smithsonian
https://www.smithsonianmag.com/smithsonian-institution/decades-tree-data-reveal-forests-under-attack-180974890/

本帖子中包含更多资源

您需要 登录 才可以下载或查看,没有帐号?立即注册

x
发表于 2020-5-18 23:01:20 发自手机 Web 版 | 显示全部楼层
OB:9:56
发表于 2020-5-18 23:38:00 | 显示全部楼层
T2【2分08秒】
Malaria parasite P may have its own clock
Explain what a clock is
The experiment was inspired by the characteristic of another parasite

T3【2分52秒】
1. experiment result: daylight, feeding doesn't affect the parasite's circadian rhythm= independent
2. the syncing of a population of parasites require the input of host's rhythm

T4【2分05秒】
The results are not surprising for R
Another research done by Duke support the conclusion
Future direction: what makes the rhythm of the parasite and the host synchronized

T5【4分44秒】
Foot prints found in 坦桑尼亚, biggest sites
discription of the site
provide evidence of female foraging groups, but not convincing

T6【2分56秒】
Moisture is the main reason of the deterioration of The Scream
Same measure could be taken to protect other works of Munch. But case-by-case
发表于 2020-5-19 02:54:10 | 显示全部楼层
T2 1:54
Malaria may have its own circadian rhythms. Its cyclic symptoms used to be thought as the circadian rhythms of host. Other parasites' own circadian rhythms inspired this new experiment.
T3 2:28
The experiment result shows that feeding and light have no influence on parasites' symptoms rhythms, which means the parasites have their own circadian rhythms. The parasites can sync with hosts' circadian rhythms. But they need an input.
T4 1:46
One independent study, separating P parasites from their host in parallel experiments, further supports that P parasites have their own circadian rhythms with the result of over 90% of these parasites showing circadian rhythms.
T5 2:53
T6 1:44
Moister is the main reason of paint fading of The Scream.
发表于 2020-5-19 07:03:23 | 显示全部楼层
[Time 2] 2:59
Researchers fund that plasmodium behave according to their own circadian, not hosts` and this finding may help scientists to treat mosquito-borne illness.
[Time 3] 5:28
The parasite`s circadian not only was not affected by the sleeping and feeding model of hosts` but also can change the host`s circadian.
[Time 4] 3:42
Other scientific researchers` responses to the finding.
[Time 5] 6:26
[Time 6] 4:25
Study shows that humidity, not light, is the principal reason that makes aged painting to decay.
发表于 2020-5-19 10:36:41 | 显示全部楼层
T2: 1'57
T3: 1'53
T4: 1'23
T5: 3'05
T6: 2'08
OBSTACLE: 8'13
发表于 2020-5-19 11:34:23 | 显示全部楼层
[Time 2]        1‘20
[Time 3]        1‘53
[Time 4]        1‘00
[Time 5]        2‘42
[Time 6]        1'58
[Paraphrase 7]        7'18
发表于 2020-5-19 13:10:51 | 显示全部楼层
studies shows that older barn owls sharing their food with younger siblings.

Antagonistic 对立的
Sharing is caring

Malaria parasites may have their own circadian rhythms
[Time2]3’22
[Time3]3’42
[Time4]2’

Scientists recently found that Plasmodium parasites have their own biological clocks which is independent of their host. Then the passage depicts the process how researchers find it in detail. In the lab, the researchers observed that the timing of changes in the parasites’ gene activity levels in the mice which in the constant darkness was similar to that of mice exposed to regular day-light cycles. Another experiment showed that the hosts’feeding schedule made no difference to the circadian rhythm of the parasites. Furthermore, scientists found that the parasites attempted to keep their circadian rhythms align with their host’s.  Next steps are that scientists will try to reveal the clock’s molecular underpinnings and how the clock interacts with that of the host.

Mutant 突变体
Stimuli: 促进因素( stimulus的复数)
Possess their own circadian rhythms
The Plasmodium in those mice kept the same internal rhythms as those in mice that were fed once daily.
The parasites attempted to synchronize their own clocks to that of their host’s
Syncing up all the clocks in a population of parasites inside of a host does apparently require input from the host’s rhythms

Africa’s biggest collection of ancient human footprints has been found
[Time5]3’51
There are more than 400 human footprints left by the ancient African hunter-gathers in hardened volcanic sediment. The evolutionary biologist are trying to figure out the ancient people’s social life by analyzing the footprints though it is hard to specify what the ancient are doing based on the foot impressions.


Vicinity : the immediately surrounding area
Hominid: a human, or an ancient creature from which humans developed
Peek: to look
More than 400 human footprints preserved in hardened volcanic sediment are proving a rare peek at social life among ancient East African hunter-gathers

Moisture, not light, explains why Munch’s ‘The scream’ is deteriorating
[Time6]2’54

The iconic work “The Scream” has rarely been displayed because it has to be preserved under a harshly controlled environment, controlled lighting and about 50 percent humidity. However, recent findings shows that moisture is the main factor for the deterioration, while light plays only a minor role which means that the painting may can be open displayed to the public again if under adequate preservation and it is also a inspiring indication for preserving other paintings.

New insight into paint preservation could help “the scream” show its face in public again
Iconic: very famous or popular
Eg. John Lennon gained iconic status following his death
Cadmium: 镉
Flaking off:剥落
Fleck:a small mark or spot
Culprit: a fact or situation that is the reason for sth bad happening
发表于 2020-5-19 19:59:37 | 显示全部楼层
MAY19th
R1
Different from other birds, older barn owls donate their food to younger one.

T2  02'14  [246]
Researchs show that malaria parasites have their own circadian rhythms.

T3  02'46  [312]
the parasites attempted to synchronize their own clocks to that of their host’s.

T4 02'20
Further support for Plasmodium’s internal clock //“it’s still possible [the parasites] keep time in a simpler way
发表于 2020-5-19 23:45:30 | 显示全部楼层
T2: [246 words] 2’05’’
T3: [312 words] 2’27’’
T4: [254 words] 2’00’’
Study shows that malaria parasite has their own circulation clock, independent of its host’s. Malaria is a detrimental disease that afflicts millions of people in the world and the finding may help to find effective treatment in terms of disrupting parasite’s clock. The internal clock helps the body to function according to a repetitive pattern. There are three groups of experiments conducted to confirm the result. First one put mice in the dark, second one feed them between different time intervals and the last one has completely disrupted circulation clock. Scientists find that parasites in all these group have similar clock, which is their own. However, clocks between the parasite and host are slightly related: if host has slower period, parasite will adjust itself to be slower as well. Another experiment isolated parasite and found that most of genes are clock controlled. Further research will be conducted.
您需要登录后才可以回帖 登录 | 立即注册

Mark一下! 看一下! 顶楼主! 感谢分享! 快速回复:

手机版|Archiver|ChaseDream京公网安备11010202008513号 京ICP证101109号 京ICP备12012021号

GMT+8, 2020-5-28 01:03 , Processed in 0.161967 second(s), 6 queries , Memcache On.

ChaseDream 论坛

© 2003-2020 ChaseDream.com. All Rights Reserved.

返回顶部