2012年06月05日

この星を壊さずに養う


Feeding the Planet Without Destroying It
( TIME )

Climate change is the environmental problem that obsesses us, the one
that's the focus of high-flying international summits and hardcore
national politics. But it's not the only environmental problem -- and
it's not even the biggest one. That happens to be the crisis in
agriculture and land use, the subject of what Jon Foley -- the head of
the University of Minnesota's Institute on the Environment -- calls the
"other inconvenient truth." Put simply, the act of feeding 7 billion
plus human beings already puts more stress on the planet than any other
single activity -- and with both population and global wealth
continuing to grow, we're going to need to figure out a way to produce
more food without further damaging the environment. Otherwise we may
end up running out of both food and the planet.

Of course, exactly how we should address these problems is the subject
of fierce debate in the U.S. and beyond. Is the solution to go organic
as much as possible, or should we focus on trying to extend the
fertilizer and irrigation of the Green Revolution to underperforming
agricultural areas in Africa and Asia? Do we need to change our diet
and reduce meat consumption, or is it simply unrealistic to expect more
of us to become semi-vegetarians -- especially among the rising global
middle class just getting a chance to eat like Americans? How much
value do intact forests and wildlife habitat have as we struggle to
feed the 1 billion people who go to bed hungry each night? And is it
really food production we need to improve, or distribution?

That's worrying enough today, given the fact that so many human beings
remain hungry even in this moment of unprecedented abundance. But
depending on population growth and global diets, we may need to produce
twice as much food by mid-century as we do now. The simplest way to
grow more food is to farm on more land, but that would come with major
environmental consequences. The arable territory that we haven't
transformed into cropland or pastureland tends to be forest, including
the great rainforests of South America and Asia. Cutting those forests
down -- as we're already doing now -- might help produce more food, but
it would come with a major environmental cost. We'd be wiping out the
most important wildlife habitats left on this crowded planet, even as
we add more carbon to the atmosphere through deforestation. "We need to
freeze the footprint of agriculture," says Foley. "We need to farm the
land we do farm better."

So what do we do then? Foley calls for something he terms
"terraculture" -- essentially farming done with the planet in mind.
That means taking the best of both conventional and organic
agriculture, using water far more efficiently for irrigation than we do
now and even altering our diets. The last bit isn't about farming, but
it could be critical. Much of the grain grown in developed nations goes
to feed not human beings but domesticated animals, and inefficiently
too -- one filet mignon requires 32 lbs. of corn, and converts that
grain into calories at just 3% efficiency. Globally we'll likely need
to eat less meat -- if only to give parts of the growing developing
world space to eat a little meat -- and, at least in much of the
unhealthily overfed West, eat fewer calories overall. That might help
reduce global food waste -- one out of every three calories produced
globally are never eaten, which isn't just a waste of food but of
water, land and energy.

Answering the other inconvenient truth is going to require a lot of
changes, from the individual consumers up to the massive global
companies that produce and sell much of the food we eat. That won't be
simple, but as Foley says: "There is no silver bullet solution. But
there is silver buckshot." And we'll need it all.

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posted by K.Andoh | Comment(0) | 科学 | このブログの読者になる |

2012年06月01日

生殖遺伝子の発見で男性用避妊薬の開発に道が開かれるのか?


Could a Fertility Gene Discovery Lead to New Male Contraception?
( TIME )

Condoms or a vasectomy are basically the only contraceptive options
currently available for men. But a new gene discovery by infertility
researchers at the Centre for Reproductive Health at the University of
Edinburgh suggests that the development of a male contraceptive pill
could someday be possible.

While studying infertility in mice, the researchers identified a gene
called Katnal1 that appears to be critical during the late stages of
sperm production. In the testes, Katnal1 regulates a protein needed by
cells that support sperm maturation; without it, sperm do not develop
properly and the body disposes of them.

In lab studies, the research team found that mice with genetic
mutations that interrupted Katnal1 became infertile.

Although the research is still in the preliminary stages, the authors
say that if a drug could be developed to hinder Katnal1, it could
potentially serve as a reversible contraceptive.

“If we can find a way to target this gene in the testes, we could
potentially develop a non-hormonal contraceptive,” researcher Dr. Lee
Smith of the University of Edinburgh said in a news release. ”The
important thing is that the effects of such a drug would be reversible
because Katnal1 only affects sperm cells in the later stages of
development, so it would not hinder the early stages of sperm
production and the overall ability to produce sperm.”

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posted by K.Andoh | Comment(0) | 科学 | このブログの読者になる |

2012年04月13日

DNA解読 あなたが思うほど有益ではなく


Decoding Your DNA: Not as Useful as You’d Think
( TIME )

Gene scans for everyone? Not so fast. New research suggests that for
the average person, decoding your own DNA may not turn out to be a
really useful crystal ball for future health.

Today, scientists map entire genomes mostly for research, as they study
which genetic mutations play a role in different diseases. Or they use
it to try to diagnose mystery illnesses that plague families. It’s
different from getting a genetic test to see if you carry, say, a
particular cancer-causing gene.

But as genome mapping gets faster and cheaper, scientists and consumers
have wondered about possible broader use: Would finding all the
glitches hidden in your DNA predict which diseases you’ll face decades
later?

But a negative test for most of the rest of the diseases doesn’t mean
you won’t get them. It just means that you’re at no more risk than
the general population. Those are the findings Vogelstein’s team
reported Monday in the journal Science Translational Medicine. Why?
Cancer, for example, typically doesn’t result from inherited genes but
from mutations that can form anytime, Vogelstein explained. Many other
common diseases are influenced by lifestyle and environment -- so
you’d still have to eat well, exercise and take the other usual
precautions.

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posted by K.Andoh | Comment(0) | 科学 | このブログの読者になる |

2012年04月03日

男性のはげの型を発見 治療法は見つかるのか?


Study Finds Pattern in Male Baldness: Could There Be a Cure?
( TIME )

Has the world finally found an answer to man’s hairiest question?
Shall great tufts again sweep across the foreheads whence they
retreated years ago?

Don’t start selling all your wig company stock just yet, but according
to a recent study in the journal Science Translational Medicine,
researchers have identified a protein that appears to play a role in
male pattern baldness -- and inhibiting that protein, they believe, may
allow dormant hair follicles to rise again.

Like many proteins, the name is a mouthful: prostaglandin D2, or PGD2.
University of Pennsylvania’s Luis A. Garza and his team first compared
the complete genetic makeup of hairy and not-so-hairy areas on five
balding men’s scalps. Through that analysis, they found higher
concentrations of the gene that produces PGD2 in the bald parts. In 17
subsequent samples of scalp tissue, they found the concentration of the
protein to be three times greater in men’s bare spots than in bushy
spots. The researchers also used mice and human-hair cultures to show
that inordinate amounts of the protein slowed or stopped growth.

Male-pattern baldness affects tens of millions of men in America, and
about 80% of white men before they hit age 70. The erosion can start in
one’s teens but is more likely to occur later on; according to the
National Library of Medicine, more than 50% of men over the age of 50
have some amount of hair loss. The results from this study could be
mane-changers, though as with so many promising findings, treatments
based on them are still years away.

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posted by K.Andoh | Comment(0) | 科学 | このブログの読者になる |

2012年03月02日

子供と睡眠の歴史 この子が早く寝ない訳


A History of Kids and Sleep: Why They Never Get Enough
( TIME )

For many a frazzled parent, bedtime -- their children’s, that is -- is
the best part of the day. But it can be hard to ease snooze-averse kids
into bed, and now a new study confirms that this is an age-old problem:
children have consistently gotten less sleep than recommended
guidelines, for at least the past 100 years.

Researchers from the University of South Australia did some historical
spelunking, looking for every study about sleep duration in children
beginning from the end of the 19th century through 2009. They
discovered 300 such studies, dating all the way back to a French paper
from 1897, and found that both age-specific recommendations for
appropriate sleep and the amount of time kids actually spend in
dreamland both declined at similar rates: 0.71 minutes per year for
recommendations versus o.73 minutes per year for actual sleep duration,
according to the study published Monday in the journal Pediatrics.
Across the board, children got about 37 minutes less sleep than was
recommended.

Throughout the study period, concerns were expressed that modern life
and overstimulation prevented children from getting the sleep they
need. As far back as the late 19th century, an editorial in the British
Medical Journal bemoaned our sleepless society, the stress and bustle
of everyday life, the gaslights and the trolley cars. In 1905, one
study noted that “this is a sleepless age and more and more … we are
turning night into day.” Says Olds: “Throughout the 100-year period,
we have been blaming whatever the new technology is -- radio, TV, the
Internet. Information is coming in so fast that we never wind down.”

“We’re not saying kids don’t need more sleep,” says Olds. “My
hunch is yes, they do need more sleep, but we haven’t seen good
evidence of that.”

The take-home message, according to Olds? “Never trust sleep experts.”

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posted by K.Andoh | Comment(0) | 科学 | このブログの読者になる |

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