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Don't wash those fossils!
Standard museum practice can wash away DNA.
1.Washing, brushing and varnishing fossils — all standard conservation
treatments used by many fossil hunters and museum curators alike — vastly
reduces the chances of recovering ancient DNA.
2.Instead, excavators should be handling at least some of their bounty with
gloves, and freezing samples as they are found, dirt and all, concludes a paper
in the Proceedings of the National Academy of Sciences today.
3.Although many palaeontologists know anecdotally that this is the best way
to up the odds of extracting good DNA, Eva-Maria Geigl of the Jacques Monod
Institute in Paris, France, and her colleagues have now shown just how important
conservation practices can be.This information, they say, needs to be hammered
home among the people who are actually out in the field digging up bones.
4.Geigl and her colleagues looked at 3,200-year-old fossil bones belonging to
a single individual of an extinct cattle species, called an aurochs.The fossils
were dug up at a site in France at two different times — either in 1947, and
stored in a museum collection, or in 2004, and conserved in sterile conditions
at -20 oC.
5.The team's attempts to extract DNA from the 1947 bones all failed.The newly
excavated fossils, however, all yielded DNA.
6.Because the bones had been buried for the same amount of time, and in the
same conditions, the conservation method had to be to blame says Geigl."As much
DNA was degraded in these 57 years as in the 3,200 years before," she says.
Wash in, wash out
7.Because many palaeontologists base their work on the shape of fossils
alone, their methods of conservation are not designed to preserve DNA, Geigl
explains.
8.The biggest problem is how they are cleaned.Fossils are often washed
together on-site in a large bath, which can allow water — and contaminants in
the form of contemporary DNA — to permeate into the porous bones."Not only is
the authentic DNA getting washed out, but contamination is getting washed in,"
says Geigl.
9.Most ancient DNA specialists know this already, says Hendrik Poinar, an
evolutionary geneticist at McMaster University in Ontario, Canada.But that
doesn't mean that best practice has become widespread among those who actually
find the fossils.
10.Getting hold of fossils that have been preserved with their DNA in mind
relies on close relationships between lab-based geneticists and the excavators,
says palaeogeneticist Svante P bo of the Max Planck Institute for Evolutionary
Anthropology in Leipzig, Germany.And that only occurs in exceptional cases, he
says.
11.P bo's team, which has been sequencing Neanderthal DNA, continually faces
these problems."When you want to study ancient human and Neanderthal remains,
there's a big issue of contamination with contemporary human DNA," he says.
12.This doesn't mean that all museum specimens are fatally flawed, notes P
bo.The Neanderthal fossils that were recently sequenced in his own lab, for
example, had been part of a museum collection treated in the traditional way.But
P bo is keen to see samples of fossils from every major find preserved in line
with Geigl's recommendations — just in case.
Warm and wet
13.Geigl herself believes that, with cooperation between bench and field
researchers, preserving fossils properly could open up avenues of discovery that
have long been assumed closed.
14.Much human cultural development took place in temperate regions.DNA does
not survive well in warm environments in the first place, and can vanish when
fossils are washed and treated.For this reason, Geigl says, most ancient DNA
studies have been done on permafrost samples, such as the woolly mammoth, or on
remains sheltered from the elements in cold caves — including cave bear and
Neanderthal fossils.
15.Better conservation methods, and a focus on fresh fossils, could boost DNA
extraction from more delicate specimens, says Geigl.And that could shed more
light on the story of human evolution.
(640 words nature )
Glossary
Palaeontologists 古生物学家
Aurochs 欧洲野牛
Neanderthal (人类学)尼安德特人，旧石器时代的古人类。
Permafrost (地理)永冻层
Questions 1-6
Answer the following questions by using NO MORE THAN THREE WORDS for each
answer.
1.How did people traditionally treat fossils?
2.What suggestions do Geigl and her colleagues give on what should be done
when fossils are found?
3.What problems may be posed if fossil bones are washed on-site? Name
ONE.
4.What characteristic do fossil bones have to make them susceptible to be
contaminated with contemporary DNA when they are washed?
5.What could be better understood when conservation treatments are
improved?
6.The passage mentioned several animal species studied by researchers.How
many of them are mentioned?
Questions 7-11
Do the following statements agree with the information given in the passage?
Please write TRUE if the statement agrees with the writer FALSE if the statement
does not agree with the writer NOT GIVEN if there is no information about this
in the passage.
7.In their paper published in the Proceedings of the National Academy of
Sciences，Geigl and her colleagues have shown what conservation practices should
be followed to preserve ancient DNA.
8.The fossil bones that Geigl and her colleagues studied are all from the
same aurochs.
9.Geneticists don't have to work on site.
10.Only newly excavated fossil bones using new conservation methods suggested
by Geigl and her colleagues contain ancient DNA.
11.Paabo is still worried about the potential problems caused by treatments
of fossils in traditional way.
Questions 12-13
Complete the following the statements by choosing letter A-D for each
answer.
12.“This information” in paragraph 3 indicates:
[A] It is critical to follow proper practices in preserving ancient DNA.
[B] The best way of getting good DNA is to handle fossils with gloves.
[C] Fossil hunters should wear home-made hammers while digging up bones.
[D] Many palaeontologists know how one should do in treating fossils.
13.The study conducted by Geigl and her colleagues suggests:
[A] the fact that ancient DNA can not be recovered from fossil bones
excavated in the past.
[B] the correlation between the amount of burying time and that of the
recovered DNA.
[C] the pace at which DNA degrades.
[D] the correlation between conservation practices and degradation of
DNA.
Felicity Lawrence
Thursday December 28, 2006
The Guardian
1. Consumers are to be presented with two rival new year advertising
campaigns as the Food Standards Agency goes public in its battle with the
industry over the labelling of unhealthy foods.
2. The Guardian has learned that the FSA will launch a series of 10-second
television adverts in January telling shoppers how to follow a red, amber and
green traffic light labelling system on the front of food packs, which is
designed to tackle Britain’s obesity epidemic.
3. The campaign is a direct response to a concerted attempt by leading food
manufacturers and retailers, including Kellogg’s and Tesco, to derail the
system. The industry fears that traffic lights would demonise entire categories
of foods and could seriously damage the market for those that are fatty, salty
or high in sugar.
4. The UK market for breakfast cereals is worth ￡1.27bn a year and the
manufacturers fear it will be severely dented if red light labels are put on
packaging drawing attention to the fact that the majority are high in salt
and/or sugar.
5. The industry is planning a major marketing campaign for a competing
labelling system which avoids colour-coding in favour of information about the
percentage of "guideline daily amounts" (GDAs) of fat, salt and sugar contained
in their products.
6. The battle for the nation’s diet comes as new rules on television
advertising come into force in January which will bar adverts for unhealthy
foods from commercial breaks during programmes aimed at children. Sources at the
TV regulators are braced for a legal challenge from the industry and have
described the lobbying efforts to block any new ad ban or colour-coded labelling
as "the most ferocious we’ve ever experienced".
7. Ofcom’s chief executive, Ed Richards, said: "We are prepared to face up to
any legal action from the industry, but we very much hope it will not be
necessary." The FSA said it was expecting an onslaught from the industry in
January. Senior FSA officials said the manufacturers’ efforts to undermine its
proposals on labelling could threaten the agency’s credibility.
8. Terrence Collis, FSA director of communications, dismissed claims that the
proposals were not based on science. "We have some of the most respected
scientists in Europe, both within the FSA and in our independent advisory
committees. It is unjustified and nonsensical to attack the FSA’s scientific
reputation and to try to undermine its credibility."
9. The FSA is understood to have briefed its ad agency, United, before
Christmas, and will aim to air ads that are "non-confrontational, humorous and
factual" as a counterweight to industry’s efforts about the same time. The
agency, however, will have a tiny fraction of the budget available to the
industry.
10. Gavin Neath, chairman of Unilever UK and president of the Food and Drink
Federation, has said that the industry has made enormous progress but could not
accept red "stop" signs on its food.
11. Alastair Sykes, chief executive of Nestlé UK, said that under the FSA
proposals all his company’s confectionery and most of its cereals would score a
red. "Are we saying people shouldn’t eat confectionery? We’re driven by
consumers and what they want, and much of what we do has been to make our
products healthier," he said.
12. Chris Wermann, director of communications at Kellogg’s, said: "In
principle we could never accept traffic light labelling."
13. The rival labelling scheme introduced by Kellogg’s, Danone, Unilever,
Nestlé, Kraft and Tesco and now favoured by 21 manufacturers, uses an
industry-devised system based on identifying GDAs of key nutrients. Tesco says
it has tested both traffic lights and GDA labels in its stores and that the
latter increased sales of healthier foods.
14. But the FSA said it could not live with this GDA system alone because it
was "not scientific" or easy for shoppers to understand at a glance.
Questions 1-6
Answer the questions below using NO MORE THAN THREE WORDS from the passage
for each answer.
1. When will instructions be given on reading the color-coded labels?
2. Where can customers find the red light labels?
3. What problem is the FSA trying to handle with the labeling system?
4. Which product sells well but may not be healthy?
5. What information, according to the manufacturers, can be labeled on
products?
6. What can not be advertised during children’s programmes?
Questions 7-13
Use the information in the text to match the people (listed A-E) with the
opinions (listed 7-13) below. Write the appropriate letter (A-E) for questions
1-7.
NB You may use any letter more than once.
A Ed Richard
B Terrence Collis
C Gavin Neath
D Alastair Sykes
E Chris Wermann
7. Generally we will not agree to use the red light labels.
8. It is unreasonable to doubt if FSA is trustworthy.
9. We are trying to meet our consumers’ needs.
10. The food industry has been improving greatly.
11. The color-coded labeling system is scientific.
12. Our products will be labeled unhealthy by the FSA.
13. We are ready to confront the manufacturers.
