FYI: (edited) SCIENCE-WEEK July 18, 1997 (fwd)

Eugene Leitl (
Sun, 20 Jul 1997 14:03:29 +0200 (MET DST)

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Date: Fri, 18 Jul 1997 11:35:41 -0600
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Subject: SCIENCE-WEEK July 18, 1997

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A Free Weekly Digest of the News of Science

July 18, 1997

"It is odd, but on the infrequent occasions when I have
been called upon in a formal place to play the bongo drums,
the introducer never seems to find it necessary to mention
that I also do theoretical physics." -- Richard Feynman


Reported in This Issue:

Soviet Political Persecution of the Physicist Lev Landau
Sharp Criticism of NIH Alternative Medicine Office
An Uproar Over Scientific Fraud in Germany
Evidence of An Unusual Massive Galaxy Cluster
Analysis Suggests San Andreas Fault May Be in a Critical State
New Probe of Atomic Nucleus Proton-Proton Interactions
First Analysis of DNA from A Neanderthal Bone
An Interesting Case of Ant-Plant Mutualism
Identification of the Gene for Niemann-Pick Disease
Pathogenic Aspects of Human Mitochondrial DNA
A Recombinant Gene Therapy for Human Rheumatoid Arthritis
A Resurgence in Cuba of A Dangerous Mosquito



Gravitational lensing is the bending of light and other radiation
by a massive gravitational entity such as a star, a black hole, a
galaxy, or a cluster of galaxies. The effect is predicted by
Einstein's Theory of Relativity and was first detected during a
total solar eclipse by Eddington in 1919. The first example of
gravitational lensing of light from a quasar was discovered in
1979. The result of gravitational lensing is the production of
multiple images of the lensed object. Since the radiation
signature of every object in the sky is about as unique as a
fingerprint, when one sees a small group of nearby images with
identical radiation signatures, one concludes these are multiple
images of a single entity produced by an intervening gravita-
tional lens. This is the basis for a report this week by M.
Hattori et al (various installations in DE, JP, US) concerning
the gravitational lensing of a distant quasar (redshift parameter
z=3.27). What they have deduced from the multiple-image quasar
data is the existence of a massive galactic cluster gravitational
lens intervening between the quasar and Earth. But when one looks
for the cluster one finds only the x-ray evidence of it without
the expected luminosity of galaxies in a cluster. The conclusion
is that this lens is indeed a massive cluster of galaxies at
redshift z=1 [corresponding to approximately 3 x 10exp(10) light
years], but a cluster in which most galaxies are dark. This dark
cluster of galaxies also contains a large amount of iron. It is
apparently the most distant galactic cluster discovered in x-rays
thus far, and the authors suggest it may be a new type of
astronomical object that will require some revision of current
theoretical models of the structure and history of galactic
clusters. (Nature 10 July)

Geophysical faulting is a break in rock structure that occurs
when pressures in the Earth's crust are strong enough to cause
fracture and displacement. In some faults the movement is
vertical (thrust faulting), causing one side to be pushed above
the other, in others the displacement is horizontal. Earthquakes
usually occur at fault lines, and the relationship between the
occurrence of earthquakes and existing faults is for obvious
reasons an important area of research. The present consensus
theory of earthquakes is the elastic rebound theory in which
earthquakes are caused by the sudden release of shear strain
resulting from fault slip following years of slow strain
accumulation. In other words, what we call an earthquake is the
result of an abrupt adjustment of accumulated strain forces
produced by a discontinuity in the crust. Among the countries
with a significant interest in seismology (the study of
earthquakes) are China and the U.S., since both countries have
experienced devastating earthquakes in the past. This week there
is a report by Chi-yuen Wang and Yongen Cai (University of
California Berkeley CA US, and Peking University CN) of a model
analysis of the response of the California San Andreas fault to
regional compression. The authors conclude that regional stresses
resulting from crust plate convergence and thrust faulting in the
Coastal Ranges could trigger major earthquakes on the San Andreas
fault. The far from trivial intertext here is the collaboration
between China and the U.S. in the study of the seismology of
California. (Nature 10 July)

A quark is a hypothetical fundamental particle, having charges
whose magnitudes are one-third or two-thirds of the electron
charge, and from which the elementary particles may in theory be
constructed. The quark model of the atomic nucleus, independently
proposed by Gell-Man and Zweig in 1964, has now had 33 years to
establish itself. The current view among nuclear physicists is as
follows: each nucleus contains a population of protons and
neutrons, collectively known as nucleons, as well as a host of
other particles that bind the nucleons together. Each nucleon, in
turn, is made up of three quarks bound by what is called the
strong nuclear force. (Physicists now recognize four fundamental
forces: gravity, the electromagnetic force, the weak nuclear
force, and the strong nuclear force.) The quark model is just
that, a model, and if the model has lasted for more than 30 years
it is because with it one can explain in a consistent manner the
results of laboratory experiments involving the collisions of
particles with atomic nuclei. But no quarks have ever been
isolated, and they remain theoretical constructs. Still, if
quarks do exist, if nucleons are indeed composed of more
fundamental entities, there are always new strategies to be used
in the laboratory to examine the interaction of nucleons with the
hope of revealing their internal structures. Two weeks ago Gerco
Onderwater et al (Netherlands National Institute for Nuclear and
High-Energy Physics, Amsterdam NL) reported experimental results
that have been called by other physicists "a fundamental
milestone in the understanding of nuclear structure." In brief,
what the Dutch team has done is to knock a pair of protons out of
a nucleus at the moment when the proton-proton interactions are
at their most intense, thus providing a method to reveal the
intimate relationships between nucleons. The experiment was
designed to catch two protons at a time they were so close their
quark cores would be touching. Nuclear physicists are now hopeful
that with such a method the mysteries of nucleons may soon be
solved. (Physical Review Letters 30 June)

About 10 kilometers east of Dusseldorf in Germany, in the valley
of the Dussel, there is a little town called Neander. One hundred
and forty-one years ago, in the summer of 1856, some workmen
broke into a cave to get at the limestone inside and discovered a
set of ancient bones. Most of the bones were smashed to bits by
the workmen, but some of the bones, including part of the skull,
survived, and the skeleton was soon recognized by anthropologists
as belonging to an ancient race of men who came to be known as
the Neanderthals. A Neanderthal fossil had actually been
discovered some years earlier in Gibraltar, but not recognized as
such. Neanderthal-like fossils have also been found in France,
Spain, Italy, Yugoslavia, Iraq, China, Java, and Israel. For more
than a century, one of the central questions in paleoanthropology
has been whether modern man evolved from this race -- or was the
Neanderthal a separate branch that became extinct? Until
recently, the primary laboratory method of investigation of such
a question was analysis of the morphology of bone fragments. This
week, the field of paleoanthropology has apparently crossed an
important watershed, as M. Krings et al (University of Munich,
DE; Pennsylvania State University, US) report the first analysis
of DNA from an extinct human, in this case DNA extracted from the
actual Neanderthal skeleton found near Dusseldorf in 1856. The
key to the investigation was the analysis of mitochondrial rather
than nuclear DNA. Mitochondrial DNA is usually present in
concentrations two or three orders of magnitude greater than
nuclear DNA, and they were able to find enough of it still intact
to amplify with the PCR technique and piece together a total DNA
sequence of 379 base pairs. Comparison of this sequence with
contemporary human sequences leads to the conclusion that
Neanderthal and modern man are separate evolutionary lines, and
that the latter did not evolve from the former. The work will
have to be replicated with other Neanderthal fossils, but most
paleoanthropologists are excited by the results and expect them
to be confirmed. The technology of evolutionary paleoanthropology
has evidently now progressed from caliper measurements of bones
to measurements of bone DNA fragments. (Cell 11 July)

In biology, symbiosis is an intimate and protracted association
of individuals of different species, and mutualism is a type of
symbiosis in which both participants receive benefits from the
association. An intriguing mutualism is that between ants and
Acacia trees. In East Africa, one finds Acacia trees that are
"ant-guarded": the ants live on the trees inside modified thorns
(pseudogalls), patrol the branches, and attack any insect or
vertebrate herbivore, thus protecting the plant, but also
preserving the plant for the use of the ant. But this plant
requires cross-pollination by visiting insects in order to
reproduce, and what one observes is that during the pollination
periods the ant-guards essentially remain in the guard-house and
cross-pollination by visiting insects proceeds without
difficulty. Which of course provokes the question of what are the
signals involved in this delicate bit of cooperative maneuvering?
This week P. G. Willmer and G. N. Stone (University of St.
Andrews, UK; Oxford University, UK) report that during the
pollination period, the young Acacia flowers apparently release a
volatile chemical that deters the ant-guards. The ants thus
patrol before and after pollination, but not during the
pollination period itself. (Nature 10 July)


One of the more remarkable structures found in eukaryote cells
(cells that have internal membrane-bound organelles such as a
nucleus) is the mitochondrion. An organic chemist confronting for
the first time the exquisite catalytic polymer machinery in the
mitochondrion cannot be faulted for experiencing vertigo. Each
mitochondrion, and there can be hundreds in each living eukaryote
cell, is involved in the synthesis of high-energy phosphate
compounds absolutely essential to the viability of the cell and
its replication, and in human mitochondria it is all done with 13
different proteins and 24 different RNA molecules, all coded for
by the mitochondrion's own self-replicating DNA. Which leads us
to the second aspect of this biological wonder: all mitochondria
are apparently the relics of primitive organisms that in the
early era of the evolution of life were incorporated and coopted
into eukaryotes. They have become part of the eukaryote, dividing
when the eukaryote cell divides, replicating their own DNA, and
thus passing as partners from one cell generation to the next.
Mitochondrial genes were discovered only in 1963. And our
knowledge of the pathological effects of mutations in mito-
chondrial genes begins only in 1988. Most of these pathologies
are quite special, but this month Douglas C. Wallace (Emory
University, US), who in 1988 was the first to trace a specific
disease to an inherited mutation in a mitochondrial gene,
presents his view that defects (some of them perhaps preventable)
in mitochondrial genes may also be involved in common medical
conditions such as aging and heart disease. The first decade of
the study of mitochondrial pathology is not yet finished, but we
know enough now to expect the decades ahead will reveal signif-
icant new insights into both the pathology and molecular biology
of these remarkable structures. (Scientific American August 1997)

A cytokine is any substance that promotes cell growth and cell
division. Certain cytokines are endogenous, and need to be
controlled by cell regulatory mechanisms. When these mechanisms
fail, endogenous cytokines may be implicated in serious human
diseases such as rheumatoid arthritis, where apparently
deregulated cytokines cause the inflammatory response that
produces the symptoms. As a promoter of cell growth and division,
a cytokine acts as a messenger to cells, and the transmission of
the message requires a binding of the cytokine molecule to a
cytokine-specific receptor on the cell surface. This receptor is
either a protein or a protein complex or a part of a protein, and
one would expect that if we could synthesize the receptor and
introduce the synthesized product into the extracellular fluid,
the cytokine for which this receptor is specific would bind to
the receptor and be prevented from delivering its chemical signal
to the cells. Test-tube synthesis of most complex proteins
produced by biological cells is not yet possible, but what one
can do, after calculating the DNA code for the active part of the
receptor protein, is incorporate the necessary DNA sequence into
the genome of some mammalian cell line, and have these cells act
as chemical factories to produce the cytokine receptor that we
are unable to synthesize otherwise. We then gather the factory
product, administer it to the patient, and expect the cytokine
receptor to bind its specific cytokine in extracellular fluid and
thus reverse the course of the disease. This is essentially what
"recombinant gene therapy" is all about. It is a field less than
a decade old, and like all fields involving clinical medicine, it
moves slowly because procedures that involve human patients must
be carefully developed. This week, Larry W. Moreland et al (12
authors at various installations, US) report the successful
treatment of rheumatoid arthritis with a recombinant human
cytokine receptor complex produced by the method outlined above.
It is a beginning. Like all treatments involving recombinant gene
therapy, much work needs to be done. But the path ahead is clear,
and there is an expectation of important results from this area
of clinical medicine. (New England Journal of Medicine 17 July)

Dengue is a human disease caused by a virus, which in turn is
transmitted by a mosquito (Aedes aegypti) through a mosquito
bite. In some place, the disease may be called "breakbone fever"
or "dandy Fever". The disease is endemic throughout the tropics
and subtropics, and in adults an attack of dengue fever usually
lasts several weeks and then it passes. There is a variant,
however, that infects children, dengue hemorrhagic fever, and
this has a mortality rate of as much as 30%, most deaths
occurring in infants less than a year old. Dengue hemorrhagic
fever is prevalent in Southeast Asia, China, and Cuba. An
important fact about the disease vector, the mosquito Aedes
aegypti, is that it likes to breed around human dwellings and in
man-made containers. Which leads to the expectation that dengue
could be eradicated by a concerted effort to eliminate containers
and other man-made debris used by the breeding mosquito. Such
concerted efforts have been underway now for 50 years, and
apparently they have all failed and the mosquito Aedes aegypti
has been victorious. This week there is a report of a serious
outbreak of dengue in Santiago, Cuba, with estimates of the
number of cases as high as 30,000. (Science 11 July)


Sponsor: University of British Columbia
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20121 Milan, IT. Phone: (39) 2-874932
CONFERENCE: San Francisco (CA US)
Sponsor: Palo Alto Institute of Molecular Medicine
POSITION OPEN: Group Leader Human X-Chromosome Genome Project
Max-Planck Institute for Molecular Genetics Berlin (DE)
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American Chemical Society
U.S. National Institutes of Health
New England Journal of Medicine
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