Subject: [SciPol 609] ScienceWeek May 18, 2007

From: "Dan Agin" <[email-masked]>
Date: Fri, 18 May 2007 12:50:24 -0500

SCIENCEWEEK

May 18, 2007

Vol. 11 - Number 19

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A star is simpler than an insect.

-- Martin Rees

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Contents (full text below):

1. Developmental Biology: A Decade of Cloning Mystique

2. The New Synthesis in Moral Psychology

3. Childhood Origins of Adult Resistance to Science

4. Optics: Beyond Diffraction

5. Organic Chemistry: Molecular Cross-Talk

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1.

Science 18 May 2007: Vol. 316. no. 5827, pp. 990 - 992 DOI:
10.1126/science.1143512

Developmental Biology: A Decade of Cloning Mystique

Jose Cibelli

Ten years ago, Ian Wilmut, Keith Campbell, and their colleagues
from the Roslin Institute in Scotland announced the first cloned
adult mammal--a sheep named Dolly--using a technique called
somatic cell nuclear transfer (1). Since then, the experiment has
been independently replicated in 16 other mammalian species.
Laboratories around the world launched efforts to identify the
mechanism responsible for this phenomenon. Hundreds of peer-
reviewed manuscripts later, we are left with many unanswered
questions about the technique and are still unable to
substantially increase its efficiency. For all species cloned by
this method, less than 10% of embryos transferred into the uterus
will produce a healthy clone. Why?

Wilmut and Campbell's curiosity radically changed our views on
the plasticity of the genome. The technique, in which the nucleus
of an animal's somatic cell is inserted into an enucleated,
unfertilized egg cell (called an oocyte) of the same species,
essentially takes a differentiated cell and "turns it back," in a
developmental sense, to a zygote, poised to develop into a fetus
and mature adult that is genetically identical to the animal that
provided the somatic cell nucleus. The old dogma that a
differentiated cell can never turn back in development has been
replaced by a new one stating that somatic cell nuclear transfer
is possible and that our failures are attributable to
insufficient understanding of the mechanisms that govern how a
somatic cell nucleus is reprogrammed by the cytoplasm of an
oocyte.

When performing somatic cell nuclear transfer, we are asking a
somatic cell to turn into a gamete in a matter of hours, a
process that normally takes months (2). Shortly thereafter, we
expect such a pseudo-gamete to "turn into a fertilized egg," or
zygote (coaxed by electrical or chemical stimulation in vitro),
ready to divide and form an embryo. This is a tremendous
undertaking for a genome that the day before was governing the
identity and physiology of a completely different cell type. Now
we are faced with trying to improve a technique that supports a
process that is clearly unnatural. Should we? We cannot afford
not to. Beyond the obvious practical benefits we might expect
from achieving success--such as agricultural cloning (livestock
production) and therapeutic cloning (generating stem cell-derived
cell lines for understanding devastating diseases)--it poses a
scientific challenge that goes to the heart of developmental
biology.

Ten years have not been enough time, though; the long list of
unanswered questions about animal cloning reflects how our
understanding is stalled at a fundamental level. For instance, is
somatic cell dedifferentiation or embryonic differentiation the
step at which the process stumbles? Can we render a nucleus more
susceptible to the reprogramming action of the egg? How much
responsibility for the outcome should either constituent be
given? Can we reprogram a primate somatic cell? Why do cells,
isolated at the same time from the same tissue of a given
individual, have different cloning efficiencies? And the most
important question: What is the gene(s) whose expression in the
egg is critical for reprogramming a somatic nucleus?

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2.

Science 18 May 2007: Vol. 316. no. 5827, pp. 998 - 1002 DOI:
10.1126/science.1137651

The New Synthesis in Moral Psychology

Jonathan Haidt

People are selfish, yet morally motivated. Morality is universal,
yet culturally variable. Such apparent contradictions are
dissolving as research from many disciplines converges on a few
shared principles, including the importance of moral intuitions,
the socially functional (rather than truth-seeking) nature of
moral thinking, and the coevolution of moral minds with cultural
practices and institutions that create diverse moral communities.
I propose a fourth principle to guide future research: Morality
is about more than harm and fairness. More research is needed on
the collective and religious parts of the moral domain, such as
loyalty, authority, and spiritual purity.

If you ever become a contestant on an unusually erudite quiz
show, and you are asked to explain human behavior in two seconds
or less, you might want to say "self-interest." After all,
economic models that assume only a motive for self-interest
perform reasonably well. However, if you have time to give a more
nuanced answer, you should also discuss the moral motives
addressed in Table 1. Try answering those questions now. If your
total for column B is higher than your total for column A, then
congratulations, you are Homo moralis, not Homo economicus. You
have social motivations beyond direct self-interest, and the
latest research in moral psychology can help explain why.

In 1975, E. O. Wilson (1) predicted that ethics would soon be
incorporated into the "new synthesis" of sociobiology. Two
psychological theories of his day were ethical behaviorism
(values are learned by reinforcement) and the cognitive-
developmental theory of Lawrence Kohlberg (social experiences
help children construct an increasingly adequate understanding of
justice). Wilson believed that these two theories would soon
merge with research on the hypothalamic-limbic system, which he
thought supported the moral emotions, to provide a comprehensive
account of the origins and mechanisms of morality.

As it turned out, Wilson got the ingredients wrong. Ethical
behaviorism faded with behaviorism. Kohlberg's approach did grow
to dominate moral psychology for the next 15 years, but because
Kohlberg focused on conscious verbal reasoning, Kohlbergian
psychology forged its interdisciplinary links with philosophy and
education, rather than with biology as Wilson had hoped. And
finally, the hypothalamus was found to play little role in moral
judgment.

Despite these errors in detail, Wilson got the big picture right.
The synthesis began in the 1990s with a new set of ingredients,
and it has transformed the study of morality today. Wilson was
also right that the key link between the social and natural
sciences was the study of emotion and the "emotive centers" of
the brain. A quantitative analysis of the publication database in
psychology shows that research on morality and emotion grew
steadily in the 1980s and 1990s (relative to other topics), and
then grew very rapidly in the past 5 years.

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3.

Science 18 May 2007: Vol. 316. no. 5827, pp. 996 - 997 DOI:
10.1126/science.1133398

Childhood Origins of Adult Resistance to Science

Paul Bloom and Deena Skolnick Weisberg

Resistance to certain scientific ideas derives in large part from
assumptions and biases that can be demonstrated experimentally in
young children and that may persist into adulthood. In
particular, both adults and children resist acquiring scientific
information that clashes with common-sense intuitions about the
physical and psychological domains. Additionally, when learning
information from other people, both adults and children are
sensitive to the trustworthiness of the source of that
information. Resistance to science, then, is particularly
exaggerated in societies where nonscientific ideologies have the
advantages of being both grounded in common sense and transmitted
by trustworthy sources.

Scientists, educators, and policy-makers have long been concerned
about American adults' resistance to certain scientific ideas
(1). In a 2005 Pew Trust poll, 42% of respondents said that they
believed that humans and other animals have existed in their
present form since the beginning of time, a view that denies the
very existence of evolution (2). Even among the minority who
claim to accept natural selection, most misunderstand it, seeing
evolution as a mysterious process causing animals to have
offspring that are better adapted to their environments (3). This
is not the only domain where people reject science: Many believe
in the efficacy of unproven medical interventions; the mystical
nature of out-of-body experiences; the existence of supernatural
entities such as ghosts and fairies; and the legitimacy of
astrology, ESP, and divination (4). This resistance to science
has important social implications, because a scientifically
ignorant public is unprepared to evaluate policies about global
warming, vaccination, genetically modified organisms, stem cell
research, and cloning (1).

Here we review evidence from developmental psychology suggesting
that some resistance to scientific ideas is a human universal.
This resistance stems from two general facts about children, one
having to do with what they know and the other having to do with
how they learn.

The main source of resistance concerns what children know before
their exposure to science. Recent psychological research makes it
clear that babies are not "blank slates"; even 1-year-olds
possess a rich understanding of both the physical world (a "naïve
physics") and the social world (a "naïve psychology") (5). Babies
know that objects are solid, persist over time (even when out of
sight), fall to the ground if unsupported, and do not move unless
acted upon (6). They also understand that people move
autonomously in response to social and physical events, act and
react in accord with their goals, and respond with appropriate
emotions to different situations (5, 7, 8).

These intuitions give children a head start when it comes to
understanding and learning about objects and people. However,
they also sometimes clash with scientific discoveries about the
nature of the world, making certain scientific facts difficult to
learn. The problem with teaching science to children is thus "not
what the student lacks, but what the student has, namely
alternative conceptual frameworks for understanding the phenomena
covered by the theories we are trying to teach" (9).

Children's belief that unsupported objects fall downward, for
instance, makes it difficult for them to see the world as a
sphere-if it were a sphere, the people and things on the other
side should fall off. It is not until about 8 or 9 years of age
that children demonstrate a coherent understanding of a spherical
Earth (10), and younger children often distort the scientific
understanding in systematic ways. Some deny that people can live
all over Earth's surface (10), and when asked to draw Earth (11)
or model it with clay (12), some children depict it as a sphere
with a flattened top or as a hollow sphere that people live
inside.

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4.

Nature 447, 266-267 (17 May 2007) | doi:10.1038/447266a;
Published online 16 May 2007

Optics: Beyond Diffraction

Evgenii E. Narimanov & Vladimir M. Shalaev

A material with a cunningly designed optical response overcomes a
fundamental limit to image resolution. This 'hyperlens' produces
magnified images of objects smaller than the wavelength of the
imaging light.

When an object is illuminated, information about features smaller
than the wavelength of the incident light is carried in
evanescent waves, whose amplitudes decrease exponentially with
distance. This rapid decay means that detail is lost when an
image of the object is viewed in its far field. Two papers
published in Science1, 2 contain experimental details of a
'hyperlens' that circumvents this problem, turning evanescent
fields into propagating waves, and so producing magnified far-
field images of sub-wavelength structures.

For propagating electromagnetic waves, the wavelength defines the
scale over which the accompanying electromagnetic field varies.
When an object is moved by a distance much smaller than this
wavelength, it will be subjected to essentially the same field as
before, and an image formed by the light scattered off the object
will also remain unchanged. The light's wavelength therefore
gives a measure of the image resolution, generally referred to as
the Abbe diffraction limit3, after the nineteenth-century German
physicist Ernst Abbe.

At the heart of the hyperlens concept4, 5 lies a nanostructured
'metamaterial' whose dielectric constant - a measure of a
material's response to the electric field of the incident light -
has opposite signs in two orthogonal directions. The effect of
this anisotropy is to do away with the lower limit on the
wavelength of a propagating field that is characteristic of a
conventional, isotropic medium. With no lower limit on the
propagating light's wavelength, there is no diffraction limit -
and so, theoretically, unbounded image resolution.

As soon as waves of very small wavelength emerge from this
'optical hyperspace' into air, however, they can no longer
propagate, and again become evanescent. To deliver the sub-
wavelength information carried by such waves into the far field,
one must first increase their wavelength to the point when
propagation in air is possible. The cylinder (or half-cylinder)
geometry of the hyperlens is specifically designed to achieve
this, by slowly increasing the wavelength as the field spreads
away from the centre of the device

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5.

Nature 447, 273-274 (17 May 2007) | doi:10.1038/447273a;
Published online 16 May 2007

Organic Chemistry: Molecular Cross-Talk

Alexander Greer

There is a long way to go before artificial enzymes can reproduce
the functions of the real things. The advent of systems that
generate and respond to signals may bring that ideal a step
closer.

Molecules are often used as signals in biological systems,
triggering reactions to various stimuli. Enzymes in plants, for
example, liberate electronically excited oxygen - known as
singlet oxygen - in response to stress, eliciting protective
responses from other biomolecules1, 2. Such chemical cross-talk
has now been demonstrated in a synthetic system, as reported by
Natarajan et al.3 in the Journal of the American Chemical
Society. They have designed an artificial enzyme that generates
singlet oxygen and releases it into the surrounding solution. The
oxygen then diffuses to another, remote artificial enzyme, where
it is trapped and reacts with acceptor molecules.

Artificial enzymes have been around since the 1980s, when
chemists discovered that the hydrophobic interior environment of
enzymes could be mimicked by large 'host' molecules that
encapsulate small 'guest' molecules4. But despite the great
ingenuity applied to the design of the hosts, these systems were
primitive compared with natural, highly evolved enzyme pockets.
One big problem was devising recognition and capturing strategies
for molecules of sufficient quality to accurately direct guests
to the artificial-enzyme sites - such exquisite control is
essential for reproducing the functions of natural enzymes. An
understanding of molecular host-guest binding has slowly
developed so that, for example, we now appreciate how non-
covalent interactions can immobilize guests in a process known as
constrictive binding5. It is also possible to tailor the size and
shape of hosts, so that their geometry can direct chemical
reactions to selected sites in a guest molecule6, 7.

Natarajan et al have used such ideas in their study3. They
trapped two different guest molecules into separate hosts,
permanently isolating them from each other (Fig. 1). The first
guest was a photosensitizer - a compound that readily transfers
light energy to other molecules, so promoting them into excited
states. The second isolated guest was an alkene, which acts as an
oxygen acceptor. The encapsulated photosensitizer absorbs light
and - if the host is open to allow oxygen into its cavity -
converts ground-state oxygen into singlet oxygen, which then
escapes into the bulk solution. Some of the singlet oxygen
reaches the separate alkene-containing hosts, where it reacts
with the guest molecule. Because the alkene-containing hosts hold
their guests in a particular orientation within the cavity, some
parts of the alkene are more accessible to chemical attack than
others. The singlet oxygen therefore predominantly attacks the
alkene at the most accessible position, yielding mostly one
product. In the absence of the host, the singlet oxygen attacks
the alkene at several positions, so that a mixture of compounds
forms, with no major product8.

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