問2 下の文章中にある下線が引かれた部分(A)~(E)を日本語訳しなさい。

The End of Men? by Joe Palca

As Y Chromosome Shrinks, End of Men Pondered

Each of our cells contains 23 pairs of chromosomes. Twenty-two of those pairs are matched pairs, shared by men and women. The 23rd is different.

In women, the 23rd pair is made up of two X chromosomes. In men, it's made up of an X chromosome and a Y chromosome. That Y chromosome determines maleness in humans -- it holds genes necessary for forming testes and making sperm.

The fact that it doesn't have a matching pair poses a bit of a problem for the Y chromosome.(A)

All the other chromosomes come in two copies. Every time a cell divides, mistakes in genes can creep in. In paired chromosomes, that means that if there is a mistake on one chromosome, a cell can always get the correct gene sequence from the other chromosome.

Over time, mistakes have crept into the Y chromosome, too. But every time a gene on the Y chromosome went bad, it basically disappeared. Scientists theorize that the X and Y chromosome started out with about the same amount of genes -- about 1,000. Today, the Y chromosome has less than 80 genes.

Some geneticists think the Y chromosome is now little more than a genetic wasteland that will eventually just disappear. If that were to happen, it would certainly spell the end of sexual reproduction.(B)

But David Page of MIT's Whitehead Institute vigorously disagrees. "At the same time that it is continuing to lose genes, it's found some new ways of replenishing itself," Page says.

Last year, Page and his colleagues reported a finding that brightened the outlook for the future of men: The Y chromosome has been secretly creating backup copies of its most important genes. These are stored in the DNA as mirror images, or palindromes -- which read the same way forwards and backwards. ("Madam, I'm Adam" is a famous example.)

In Y chromosome palindromes, the first half contains the gene and the second half contains the same information, just in reverse.(C)

That means that many of the genes on the Y chromosome do occur as pairs. Page says members of these pairs appear to be swapping out or recombining with each other -- allowing the genes to repair themselves when they get damaged.

Page says this helps explain why these genes have been able to persist despite millions of years of assault from random mutations. And, he says, it means the Y chromosome won't simply keep shrinking away until it disappears altogether.

Making Sperm in the Lab

The secret of producing sperm without men appears to lie in embryonic stem cells. Under the right conditions, these cells can replenish themselves indefinitely in the laboratory, and they can, in theory, turn into any type of cell in the body.

But for a long time, many questioned whether embryonic stem cells could turn into sperm -- a highly specialized cell that's only formed after puberty. The smallest cells in the male body, sperm are programmed to find and fertilize an egg.

Last year, scientists proved that they could not only create sperm in a petri dish, but also use that sperm to fertilize a mouse egg.(D)

Led by George Daley of Children's Hospital in Boston, the researchers began their process by culturing mouse embryonic stem cells to form globular clusters called embryoid bodies.

Cells in these embryoid bodies differentiated into primitive germ cells (the precursors of eggs and sperm). The germ cells were tagged with a fluorescent chemical that allowed the scientists to isolate and track the germ cells as the body developed.

Those embryoid bodies that were allowed to grow contained cells that became mature male sex cells similar to sperm, minus the tails. Those tail-less sperm were injected directly into mouse egg cells, essentially fertilizing them. The fertilized eggs then developed into early embryos called blastocysts.

Although embryonic stem cells can make primitive spermatids, it's not known yet whether these resulting tail-less sperm will be able to do all the things that regular sperm are supposed to do.

Daley's team has not yet proved that eggs fertilized with sperm derived from embryonic stem cells will grow into a mouse pup when implanted in a mouse mom. But he's confident he'll be able to do that.

Daley also believes that what works with mouse embryonic stem cells will also work with human embryonic stem cells. But he's not trying to put men out of business -- he simply wants to study sperm cell development and infertility.

"The implications for being able to make sperm in a dish allows you to ask questions about normal sperm development, and abnormal sperm development," Daley says.(E)

Besides, Daley notes, there's still one thing that makes men indispensable: "It's clear to make a sperm cell, you do need the Y chromosome. So insofar as men are the only ones who harbor the Y chromosome, you still need a male cell."

Of course, once embryonic stem cells start producing sperm, they can keep doing so forever.

(Dec. 2004, http://www.npr.org)
コメント ( 0 ) | Trackback ( 5 )


問1 下の英文をよく読んで、記述された内容を200文字以内の日本語で要約しなさい

Garter snakes, newts in genetic war by Joe Bauman

For years, scientists at Utah States University (USU) have been documenting a "chemical arms race" between normally toxic newts and the garter snakes that eat them. Now they have discoverd the genetic changes that allow the snakes to evolve molecular defenses against the poison.

Garter snakes regularly do something you can't ― something that perhaps no other creatur but the snakes can do ― eat a rough-skinned newt and live. A newt is a member of salamander order, and rough-skinned newts are common in West Coast streams. As garter snakes have raised their chemical defenses, the newts have become more deadly. According to USU, one newt (scientific name Taricha granulosa) carries enough neurotoxins of the same type found in Japanese puffer fish to kill 50,000 mice or 10 people.

Shana L.Geffeney, a graduate student at the Logan University, is the lead author of the study published in the most recent edition of the journal "Nature*." Her co-authors are Esther Fujimoto, Edmund D. Brodie Jr. and Peter C. Ruben of USU and Edmund D. Brodie III of Indiana University. Fujimoto is now at the University of Utah, says the report.

Their study examined the way genes regulating the cell's sodium channels changed in response to the neurotoxins carried in the newt's skin. Sodium channels are openings that let sodium move in and out of the muscule cells; this movement allows the muscle to contract. When the toxin attaches to a protein that is part of the channel's structure, sodium can't move in and out and the cell can't move. Newt poison called tetrodotoxin (TTX) binds onto the protein, paralyzing muscle function. Muscles attached to the victim's bones don't work, and the person or animal unlucky enough to be poisoned by a newt will stop breathing. The poison is so deadly because it blocks activity in nerve and muscle fiber, said Geffeny.

In a 2002 study in the journal Science**, Geffeney, the Brodies (father and son professors) and Ruben showed that the newts and snakes were locked in the arms race. What's new is that they now know the molecular basis for the snake's defense. The poison binds to a particular place on the protein molecule. In most animals, these proteins are the same, and the poison bonds to an important part of the molecule. From chickens to rats and humans, the sodium channels are vulnerable to TTX. But not in the garter snake.

The snakes' genetic makeup mutated so that the protein was shaped differently. The poison could not bind onto the new shape. Snake muscles with the modified proteins were able to function even with high doses of the poison, the researchers found.

"We made specific mutations and we showed that the specific mutations altered the ability of the TTX to bind to the protein," she said. "So we ended up learning more about the shape of the protein," Geffeney was surprised to see changes in such an important part of the protein.

Another discovery was that separated populations of garter snakes differ in their amino acid sequences. In their separate habitats, at least two populations of garter snakes apparently evolved the defenses on their own. One question the team would like to answer, she said, is "How many times has this elevated level of resistance evolved?"

The elder Brodie, former chairman of USU's Biology Department, said the study has extended the research into the fields of neurobiology and genomics. "Shana set out to isolate the proteins that form the sodium channel, and could sequence those and determine the mutations that had taken place in those populations that were resistant," he said. Possibly other populations of garter snakes would show additional changes, he said. "We know that the changes have evolved at least twice independently."

So who's winning the chemical arms race? "It seems to be sliding back and forth," Brodie said. "The snakes may be ahead for the moment, but it's variable, area to area."

(Desert Morning News Monday, April 11, 2005 Utah, USA)


* Evolutionary diversification of TTX-resistant sodium channels in a predator-prey interaction
Nature 434:759-63,2005

** Mechanisms of Adaptation in a Predator-Pley Arms Race: TTX-Resistant Sodium Channels.
Science, vol.297, no.5585, 2002
コメント ( 0 ) | Trackback ( 6 )


問1: The goal of scientific research is publication. Scientists, starting as graduate students, are measured primarily not by their dexterity in laboratory manipulation, not by their innate knowledge of either broad or narrow scientific subjects, and certainly not by their wit or charm; they are measured, and become known(or remain unknown), by their publications.

問2: A scientific experiment, no matter how specutacular the results, is not completed until the results are published. In fact, the cornerstone of the philosophy of science is based on the fundermental assumption that original research must be published; only thus can new scientific knowledge be authenticated and then added to the existing date base that we call science.

問3:provide a written document

問4:"a naturarist's life would be a happy one if he had only to observe oand never to write".
コメント ( 0 ) | Trackback ( 1 )


次の文は、インテリジェント・デザイン説(知的な存在の介在によって生物が生み出されたとする説)を学校で教えることについて、Bobby Hendersonがカンザス州教育委員会などに送った公開書簡の本文である。これを読んで問題のA~Dの全てを日本語で解答しなさい。(<>はパラグラフの番号を示している)
<1> I am writing you with much concern after having read of your hearing to decide whether the alternative theory of Intelligent Design should be taught along with the theory of Evolution. I think we can all agree that it is important for students to hear multiple viewpoints so they can choose for themselves the theory that makes the most sense to them. I am concerned, however, that students will only hear one theory of Intelligent Design.

<2> Let us remember that there are multiple theories of Intelligent Design. I and many others around the world are of the strong belief that the universe was created by a Flying Spaghetti Monster. It was He who created all that we see and all that we feel. We feel strongly that the overwhelming scientific evidence pointing towards evolutionary processes is nothing but a coincidence, put in place by Him.

<3> It is for this reason that I’m writing you today, to formally request that this alternative theory be taught in your schools, along with the other two theories. In fact, I will go so far as to say, if you do not agree to do this, we will be forced to proceed with legal action. I’m sure you see where we are coming from. If the Intelligent Design theory is not based on faith, but instead another scientific theory, as is claimed, then you must also allow our theory to be taught, as it is also based on science, not on faith.

<4> Some find that hard to believe, so it may be helpful to tell you a little more about our beliefs. We have evidence that a Flying Spaghetti Monster created the universe. None of us, of course, were around to see it, but we have written accounts of it. We have several lengthy volumes explaining all details of His power. Also, you may be surprised to hear that there are over 10 million of us, and growing. We tend to be very secretive, as many people claim our beliefs are not substantiated by observable evidence. What these people don’t understand is that He built the world to make us think the earth is older than it really is. For example, a scientist may perform a carbon-dating process on an artifact. He finds that approximately 75% of the Carbon-14 has decayed by electron emission to Nitrogen-14, and infers that this artifact is approximately 10,000 years old, as the half-life of Carbon-14 appears to be 5,730 years. But what our scientist does not realize is that every time he makes a measurement, the Flying Spaghetti Monster is there changing the results with His Noodly Appendage. We have numerous texts that describe in detail how this can be possible and the reasons why He does this. He is of course invisible and can pass through normal matter with ease.

<5> I’m sure you now realize how important it is that your students are taught this alternate theory. It is absolutely imperative that they realize that observable evidence is at the discretion of a Flying Spaghetti Monster. Furthermore, it is disrespectful to teach our beliefs without wearing His chosen outfit, which of course is full pirate regalia. I cannot stress the importance of this enough, and unfortunately cannot describe in detail why this must be done as I fear this letter is already becoming too long. The concise explanation is that He becomes angry if we don’t.

<6> You may be interested to know that global warming, earthquakes, hurricanes, and other natural disasters are a direct effect of the shrinking numbers of Pirates since the 1800s. For your interest, I have included a graph of the approximate number of pirates versus the average global temperature over the last 200 years. As you can see, there is a statistically significant inverse relationship between pirates and global temperature.

<7> In conclusion, thank you for taking the time to hear our views and beliefs. I hope I was able to convey the importance of teaching this theory to your students. We will of course be able to train the teachers in this alternate theory. I am eagerly awaiting your response, and hope dearly that no legal action will need to be taken. I think we can all look forward to the time when these three theories are given equal time in our science classrooms across the country, and eventually the world; One third time for Intelligent Design, one third time for Flying Spaghetti Monsterism, and one third time for logical conjecture based on overwhelming observable evidence.

(http://www.venganza.org/index.htm より抜粋)


 Bobby Hendersonの主張する「存在」について、第4パラグラフに記載されている形状・特徴・行為について箇条書きにしなさい。


コメント ( 0 ) | Trackback ( 3 )



【第1段落】 科学的研究の目標は出版である。大学院生として始まる科学者は、実験操作の器用さや、広い科学分野あるいは狭い科学分野における本質的な知識や、当然のことながら、機転のよさや魅力によって主として評価されるのではない。科学者は出版物によって評価され、有名になるのである(あるいは無名のままである)。
【第2段落】 科学的実験は、いかにその結果が華々しいものであっても、その結果が出版されるまでは完了するものではない。実際、科学哲学の根本理念は、独創的な研究は出版されなければならないという基本的な仮定に基づいている。このような過程を経てのみ、新しい科学的知識は真正のものとして確証され、そして、我々が科学的知識と呼ぶ既存のデータベースに加えられるのである。
【第3段落】 It is not necessary for the plumber to write about pipes, nor is it necessary for the lawyer to write about cases (except brief writing), but the research scientist, perhaps uniquely among the trades and professions, must provide a written document showing what he or she did, why it was done, how it was done, and what was learned from it. The key word is reproducibility. That it what makes science and scientific writing unique.
【第4段落】 Thus the scientific must not only “do” science but must “write” science. Bad writing can and often does prevent or delay the publication of good science. Unfortunately, the education of scientists is often so overwhelmingly committed to the technical aspects of science that the (1)communication arts are neglected and ignored. In short, many good scientists are poor writers. Certainly, many scientists do not like to write. As Charles Darwin said, “(2)博物学者の生活は、もし観察しさえすればよいだけで文章は決して書かなくてもよいのなら、幸福なものであろう。

(R. A. Day, “How to write and publish a scientific paper”, Oryx Press, 1994より)

問1 第1段落を英語に訳しなさい。
問2 第2段落を英語に訳しなさい。
問3 下線部(1)を本文中(第3段落および第4段落中)の語句(英語)で言い換えなさい。
問4 下線部(2)の日本語を英語に訳しなさい。
コメント ( 0 ) | Trackback ( 6 )



コメント ( 2 ) | Trackback ( 11 )