ScienceWeek

SCIENCE-WEEK - Part 1/3

A Free Weekly Digest of the News of Science

March 27, 1998

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The first part of the human story is simple: We rose out of the
primeval muck to peer at the stars. The second part of the story
has yet to be written.
-- The Editors
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Contents of This Issue:

Part 1:
1. AN ESSAY ON SCIENTIFIC ILLITERACY
2. A MEETING TO DISCUSS GERMLINE GENETIC ENGINEERING
3. A COMPROMISE TO PROTECT RADIO-ASTRONOMY OBSERVATIONS
4. ON COSMIC ANTIMATTER
5. DISCOVERY OF MOST DISTANT GALAXY WITH REDSHIFT AT 5.34
6. AN ANALYSIS OF OPTIMAL MODULATION OF A BROWNIAN RATCHET

Part 2:
7. FESHBACH RESONANCES IN A BOSE-EINSTEIN CONDENSATE
8. PROTEIN HYDRATION IN SOLUTION: X-RAY AND NEUTRON SCATTERING
9. A SELF-REPLICATING NUCLEOSIDE SURFACTANT VESICLE SYSTEM
10. NEW FUSION PROTEIN ENABLES VISUALIZATION OF DNA IN LIVE CELLS
11. CLEAVING DNA WITH DNA
12. ACTION OF PEPTIDE NUCLEIC ACIDS TARGETED TO RIBOSOMAL RNA
13. HUMAN IMMUNE SYSTEM LINKAGE TO A PLANT DEFENSE SYSTEM

Part 3:
14. CALCIUM SENSING OF METABOTROPIC GLUTAMATE RECEPTORS
15. A MUSCLE CELL TROPHIC FACTOR THAT INCREASES INNERVATION
16. EVIDENCE FOR HUMAN WATERCRAFT 800,000 YEARS AGO
17. INVOLVEMENT OF E-CADHERIN IN ADENOMA TO CARCINOMA TRANSITION
18. NOTED EPIDEMIOLOGIST W.M. HAENSZEL DEAD AT 87

---------------------------------------------

1. AN ESSAY ON SCIENTIFIC ILLITERACY
In an essay on the scientific illiteracy of the general public,
N. Augustine (Princeton University and Lockheed Martin Corpor-
ation, US) notes the apathy concerning science and technology
that is apparently rampant in the US, and that "an indifference
toward scientific understanding is almost considered a badge of
honor." A recent US National Science Foundation survey indicates
that less than half of American adults understand that the Earth
orbits the Sun yearly; only 21% can define DNA; only 9% know what
a molecule is; 25 million Americans cannot locate the US on an
unlabeled world map. The public attitude toward science and
scientists is consistently negative. The great irony is that the
American economy and standard of living are based on a foundation
of rapid scientific advances. Augustine suggests that modern
scientists and engineers "must become as adept in dealing with
societal and political forces as they are with gravitational and
electromagnetic forces." QY: Norman Augustine, Princeton
University 609-258-3000 (Science 13 Mar 98)


2. A MEETING TO DISCUSS GERMLINE GENETIC ENGINEERING
A group of prominent molecular biologists and geneticists met on
March 20th on the campus of the University of Southern California
(US), the conference organized by Gregory Stock (Univ. Southern 
Calif., US) for the purpose of discussing various scientific and
social aspects of germline genetic engineering. Such engineering
would involve changes in the genomes of germline cells, such
changes to become permanent for succeeding generations. The
apparent consensus is that current obstacles to germline
engineering are practical rather than theoretical. Leroy Hood
(University of Washington Seattle, US) states "we have the tools,
the vision, to do systems biology the way it was never done
before."
QY: G. Stock, University of Southern California 213-740-2311.
(New York Times 21 Mar 98)


3. A COMPROMISE TO PROTECT RADIO-ASTRONOMY OBSERVATIONS
A compromise of sorts has been reached between Motorola Inc.
(US), the main operator of communications satellites, and radio
astronomers in the US, the compromise involving a time-sharing
plan. But agreements must still be effected between satellite
operators and radio observatories in Europe and Asia. The recent
compromise occurred after 5 years of a apparently "bitter"
negotiations. The Motorola group of satellites, called the
"Iridium system", their orbiting not yet completed, involves 66
satellites in low-Earth orbits to relay cellular telephone calls
from any part of the world to any other. Completion of the
orbiting of the galaxy of 66 satellites is expected by the end of
May, and the system is expected to be fully operational by
September. In the present agreement, US astronomers will 8 hours
per day between 10pm and 6am EST during which the Iridium system
will eliminate signals disrupting radio astronomy observations by
the Arecibo observatory in Puerto Rico (US).
(New York Times 20 Mar 98)

-------------------

Related Background:

IMPROVEMENTS IN ARECIBO TELESCOPE MEAN NEW ERA IN RADIO ASTRONOMY
Last Saturday, 14 June, saw an inauguration ceremony at the
Arecibo Observatory in Puerto Rico, the world's largest radio
telescope, to mark the conclusion of extensive renovations
jointly funded by the U.S. National Aeronautics and Space
Administration and the U.S. National Science Foundation. It is
expected the renovations will greatly increase the telescope's
performance and will lead to a new era in radioastronomy. Donald
Campbell, associate director of the Cornell University team that
operates the Arecibo telescope says, "...we have to think of this
as a new telescope, since just about everything has changed, save
for the primary reflector." Apparently, the range of frequencies
that can be observed has expanded by a factor of five, while the
instantaneous bandwidth (the part of the spectrum observable at
any one time) has increased 20-fold. (Nature 12 Jun 98)


4. ON COSMIC ANTIMATTER
Antiparticles are homologs of elementary particles but with
opposite charge. The positron, for example, is the antimatter
particle homologous to the electron. Matter composed entirely of
antiparticles is called antimatter, and one of the important
questions in cosmology and theoretical astrophysics is the fate
of the antimatter proposed to have been created during the Big
Bang. The idea is that at one point there were equal amounts of
matter and antimatter, and the problem is that what is detected
is apparently an asymmetric universe with naturally occurring
antiparticles in places, but no antimatter in evidence. When
matter and antimatter connect, there is mutual annihilation.
... ... Tarle and Swordy (at 2 installations, US), review the
evidence concerning cosmic antimatter and the use of this
evidence as clues to some of the mysteries of astrophysics. The
existence of antimatter was first theoretically predicted by
P.A.M Dirac in 1928, and the first antiparticle, the positron,
was experimentally detected by Carl D. Anderson in 1932. The
first antiproton was created in 1955, and the first synthesis of
transient antihydrogen, merging positrons and antiprotons,
occurred in 1995. Astrophysicists believe most of the anti-
particles observed by upper atmosphere devices were created by
violent collisions of subatomic particles in interstellar space.
A number of balloon facilities have been launched to observe the
interaction of antiparticle cosmic rays with the outer portions
of the Earth's atmosphere, but to date no evidence of a natural
antiparticle heavier than an antiproton has ever appeared, and no
evidence of antimatter. But it is believed antistars and
antigalaxies might still lurk somewhere in the universe, billions
of light years from our own galaxy. The authors are associated
with the High Energy Antimatter Telescope (HEAT), a 2300 kilogram
device balloon-launched for the first time in 1994.
QY: Gregory Tarle, Dept. of Physics, Univ. of Michigan 313-764-
7433 (Scientific American April 1998)

-------------------

Related Background:

NEWLY OBSERVED POSITRON CLOUD SUGGESTS AGITATION IN OUR GALAXY
Our galaxy, the Milky Way, has always been considered to be a
relatively tranquil system. But now a team of astrophysicists
led by William Purcell (Northwestern University) and James
Kurfess (U.S. Naval Research Laboratory), using the orbiting
Compton Gamma Ray Observatory, have detected a cloud of
positrons, the antimatter equivalent of electrons, apparently
near the galactic center. There is speculation this cloud may be
related to a cluster of stellar explosions at the galactic
center about 10 million years ago. Not all astrophysicists agree
with this interpretation, however, and the evidence is yet too
scanty to delineate the complete nature and history of the
positron cloud. But there is apparently now agreement that our
galaxy is not as tranquil as was thought, and that considerable
turmoil, whether due to supernovas or black holes, existed at
the center. (Science 9 May 98)

-------------------

ANALYSIS INDICATES ABSENCE OF ANTIMATTER GALAXIES
Antiparticles are homologs of elementary particles but with
opposite charge. The positron, for example, is the antimatter
particle homologous to the electron. Matter composed entirely of
antiparticles is called antimatter, and one of the important
questions in cosmology and theoretical astrophysics is the fate
of the antimatter proposed to have been created during the Big
Bang. The idea is that at one point there were equal amounts of
matter and antimatter, and the problem is that what is detected
is apparently an asymmetric universe with no antimatter in
evidence. When matter and antimatter connect, there is mutual
annihilation with the emission of high energy gamma rays, so
astronomical gamma ray analysis may reveal the presence of
antimatter. Gamma-ray spectroscopy, which requires extra-
terrestrial instrumentation because of the impenetrability of the
Earth's atmosphere, is therefore an essential method in the
search for cosmic antimatter. Andy Cohen et al (3 authors at 3
installations, US, CH) report they have calculated the energy
that would have been emitted when primordial matter and
antimatter met and were annihilated, and when the results are
compared with actual measurements of the gamma-ray background,
what is present in the gamma-ray background radiation is only
one-fifth of what is expected. Astrophysicists are evidently
impressed with this work, which will be published in a few months
in the Astrophysical Journal. QY: Sheldon Glashow, Harvard Univ.
(617) 495-3752 (Science 10 Oct 97)


5. DISCOVERY OF MOST DISTANT GALAXY WITH REDSHIFT AT 5.34
The Keck telescopes are a pair of twin telescopes at the W. M.
Keck Observatory on Mauna Kea, HI US, each with 10 meter mirrors,
the pair constructed 1992 - 1996. The installation is managed by
the University of California (US) and the California Institute of
Technology (US). Redshift (symbol: z) is a lengthening of the
wavelengths of electromagnetic radiation from a source caused
either by the movement of the source (Doppler effect) or by the
expansion of the universe (cosmological redshift). Redshift is
defined as the change in wavelength of a particular spectral line
divided by the unshifted wavelength of that line. Large redshifts
imply large radial velocities (which imply large distances,
according to current cosmological theory), but at redshifts
greater than about 0.2 there is a relativistic divergence from a
linear relation. A redshift of 4.0 corresponds to an object
receding with a radial velocity 92% that of the velocity of
light. Until now, the largest astrophysical redshift observed was
a galaxy at z = 4.9, implying a distance of approximately 13
billion light years. ... ... Dey et al (5 authors at 2 install-
ations, US) report observations using the 10-meter Keck telescope
of what is apparently the most distant galaxy yet observed, the
object exhibiting a redshift of 5.34. The new object has been
labelled RD1. It is too faint for a full spectrum to be observed,
but it shows relatively strong ultraviolet emission, interpreted
as a possible indication of newly formed stars in a young galaxy.
The discovery of a formed galaxy at such a high redshift, which
implies an age of less than 1 billion years, places an important
constraint on cosmological theories of the evolution of the early
universe. QY: A. Dey, Univ. of Calif. Berkeley, Dept. Astronomy
510-643-8520 (Science 13 Mar 98)

-------------------

Related Background:

MOST DISTANT GALAXY OBSERVED AT REDSHIFT 4.92
Until now, the most distant objects identified in the universe
have been quasars, intense radiation sources first discovered in
1963. This is evidently no longer the case, as Marijn Franx et al
(installations in NL and US) recently reported. A galaxy has now
been identified with a redshift of 4.92, which means its distance
is further than the quasar PC1247+34 (redshift 4.90). The calcul-
ated distance of the galaxy from Earth is 13 billion light years,
the calculation based on a Hubble constant assumption that gives
the age of the universe at 14 billion years. The observations
were made with one of the Keck telescopes in Hawaii, the detect-
ion and spectroscopic analysis of the galaxy made possible by a
gravitational lens produced by a another galaxy 5 billion light
years from Earth in the path from the distant galaxy. QY: Garth
D. Illingworth, Univ. Calif. Santa Cruz (408) 429-4008
(Astrophysical J. Letters 10 Sep) (see Background Note #2)


6. AN ANALYSIS OF OPTIMAL MODULATION OF A BROWNIAN RATCHET
In general, "Brownian particles" are small particles suspended in
a fluid that show random movements caused by statistical pressure
fluctuations. In the context of this report, the phrase
"spatially anisotropic modulated potential" refers to a
direction-dependent time-variant applied force field, and the
term "synergy" refers to the interaction of two or more effects
such that the combined total effect is greater than the sum of
the individual effects. ... ... Tarlie and Astumian (University
of Chicago, US) present a theoretical analysis of the dynamics of
a Brownian particle moving in a spatially anisotropic modulated
potential. Their analysis indicates that the class of modulation
that maximizes the flow is a time-dependent square wave, and that
adding a weak homogeneous force in synergy with the square wave
modulation can cause particles of slightly different size to move
in opposite directions, and that the synergistic change in
velocity caused by the added weak force can be much greater than
the drift velocity that would be caused by the added weak force
alone. The authors suggest their results have applications for
continuous separation techniques for microscopic particles and
biopolymers, and that the enhancement by optimal modulation of
the sensitivity to the weak external force, thus allowing a weak
force to control a large current, is a mechanical analogue of a
transistor.
QY: R. Dean Astumian
dastumia@surgery.bsd.uchicago.edu
(Proc. Natl. Acad. Sci. US 3 Mar 98)

(continued in Part 2)

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SCIENCE-WEEK - Part 2/3

A Free Weekly Digest of the News of Science

March 27, 1998

Contents of Part 2:

7. FESHBACH RESONANCES IN A BOSE-EINSTEIN CONDENSATE
8. PROTEIN HYDRATION IN SOLUTION: X-RAY AND NEUTRON SCATTERING
9. A SELF-REPLICATING NUCLEOSIDE SURFACTANT VESICLE SYSTEM
10. NEW FUSION PROTEIN ENABLES VISUALIZATION OF DNA IN LIVE CELLS
11. CLEAVING DNA WITH DNA
12. ACTION OF PEPTIDE NUCLEIC ACIDS TARGETED TO RIBOSOMAL RNA
13. HUMAN IMMUNE SYSTEM LINKAGE TO A PLANT DEFENSE SYSTEM

----------------------------------------------------------------

7. FESHBACH RESONANCES IN A BOSE-EINSTEIN CONDENSATE
In 1997, Steven Chu, Claude Cohen-Tannoudji, and William D.
Philips shared the Nobel Prize in Physics for their work in the
1980s involving laser-cooled atoms, work that ultimately led to
the cooling of atoms to extremes close to absolute zero degrees
kelvin, and finally to the creation by Anderson et al (Science
269:198 1995) of a Bose-Einstein condensation in a dilute gas of
rubidium atoms. The essential idea behind these techniques
involves a reduction in the momentum of an atom when it absorbs a
photon. Bose-Einstein statistics is the statistical mechanics of
a system of indistinguishable particles for which there is no
restriction on the number of particles that may simultaneously
exist in the same quantum energy state. Bosons are particles that
obey Bose-Einstein statistics, and they include photons, pi
mesons, all nuclei having an even number of particles, and all
particles with integer spin. In low temperature physics, the
Bose-Einstein condensation is a phenomenon that occurs in the
study of systems of bosons: below a critical temperature, the
quantum ground state becomes highly populated, individual wave
equations merging into a single wave equation, the particles
indistinguishable, and the condensate of particles behaving as a
singe entity. The term "Feshbach resonance" refers to a transient
"sticking" of two colliding atoms, the sticking involving a
resonance coupling that occurs when the molecular state has
nearly zero energy. The term "optical trapping" refers to the
confinement of entities in a restricted geometry by the
controlled action of light. In this report, the term "inelastic"
refers to a collision process in which the total kinetic energy
of the colliding particles is not the same after the collision as
before it, and the term "coherent beams of atoms" refers to beams
composed of atoms moving in unison. ... ... Inouye et al (6
authors at Massachusetts Institute of Technology, US) report new
observations in a Bose-Einstein condensate. It has long been
predicted that the scattering of ultra-cold atoms can be altered
significantly through a so-called "Feshbach resonance". Two such
resonances have now been observed in optically trapped Bose-
Einstein condensates of sodium atoms by varying an external
magnetic field. The resonances gave rise to enhanced inelastic
processes and a dispersion variation of the scattering length by
a factor of over two. The authors suggest these results open new
possibilities for the study and manipulation of Bose-Einstein
condensates, may also be important in atom optics, for modifying
the atomic interactions in an atom laser, or more generally, for
controlling nonlinear coefficients in atom optics with coherent
beams of atoms. QY: W. Ketterle, Mass. Inst. of Technology 617-
253-1000 (Nature 12 Mar 98)


8. PROTEIN HYDRATION IN SOLUTION: X-RAY AND NEUTRON SCATTERING
The dissolution of a solute in a solvent is based on interactions
of the solute molecules and solvent molecules, and in the case
where the solvent is water, there is evidence that water
molecules can interact strongly enough with solute molecules, via
hydrogen bonds or other weak interactions, so that a "primary" or
first hydration shell of water molecules essentially remains
attached to each solute molecule and moves with each solute
molecule in various force fields. Since proteins in their natural
state are in an aqueous environment, and since the biological
function of proteins almost always depends on their folding
structure, it is of some importance to understand how water
interacts with proteins, and what role this interaction plays in
the structure and biological function of the protein molecule.
... ... Svergun et al (6 authors at 5 installations, DE RU FR SE)
report an investigation in parallel of 3 different proteins with
known atomic resolution crystal structure (lysozyme, E. coli
thioredoxin reductase, and protein R1 of E. coli ribonucleotide
reductase), the experimental observations involving x-ray and
neutron scattering of the proteins in H(sub2)O and D(sub2)O
solutions. The results indicate the existence of a first
hydration shell with an average density approximately 10% larger
than that of the bulk solvent in the conditions studied.
Comparing these with other studies, the authors suggest this may
be a general property of aqueous interfaces with protein.
QY: D.I. Svergun (svergun@embl-Hamburg.de)
EMAIL
(Proc. Natl. Acad. Sci. US 3 Mar 98)


9. A SELF-REPLICATING NUCLEOSIDE SURFACTANT VESICLE SYSTEM
The term "lipids" refers to a varied group of small organic
molecules characterized by insolubility in water and relative
solubility in various organic solvents. Included in the category
are fats, waxes, oils, carotenoids, and steroids. A "nucleoside"
is a purine or pyrimidine linked to a sugar (either ribose or
deoxyribose. (Note: a "nucleotide" is a nucleoside to which one
phosphate group has been attached.) A surfactant (also called
surface-active agent) is a soluble compound that reduces the
surface tension of liquids, or reduces the interfacial tension at
a liquid-liquid or liquid-solid interface. Many lipids are
surfactants and spontaneously form organized structures at
interfaces. In general, "vesicles" are small spherules with
liquid interiors. ... ... Researchers in Switzerland report the
design of a water-insoluble lipid that converts to a nucleoside-
based surfactant that spontaneously forms self-replicating giant
vesicles of lipid bilayer-coated water globules. The process is
essentially autocatalytic: surfactant is formed; molecules
organize themselves into bilayers that sequester the insoluble
precursor; the precursor thus becomes more exposed to the basic
solution that creates more surfactant. QY: A. Veronese, Swiss
Federal Institute of Technology Zurich, CH)
(Chem. & Eng. News 16 Mar 98)


10. NEW FUSION PROTEIN ENABLES VISUALIZATION OF DNA IN LIVE CELLS
Eukaryotic cells are cells having membrane bound organelles such
as a nucleus, and the term "histones" refers to a group of 8
small basic (as opposed to acidic) proteins found in combination
with nucleic acids in eukaryotic chromosomes. The histone-nucleic
acid complexes are essential aspects of chromosome molecular
architecture. ... ... A class of DNA-histone assemblies typical
of many cancer cells called "double minute chromosomes" have
until now been difficult to visualize because of their small
size. Now a group at the Salk Institute (US) has developed a
working method involving a fluorescent fusion protein. The method
involves fusing a human histone gene to the gene for a green
fluorescent jellyfish protein, with the combined new gene
expressed in a human cell line. QY: T. Kanda, Salk Institute,
10010 N. Torrey Pines Road, La Jolla, CA 92037 US.
(Curr. Biol. 8:377 1998)


11. CLEAVING DNA WITH DNA
A "nucleoside" is a purine or pyrimidine base (as opposed to an
acid) linked to a sugar. A "nucleotide" is a nucleoside with one
phosphate group attached, and it is the nucleotides that are the
entities that make up a polynucleotide chain such as DNA or RNA.
An "oligonucleotide" is a short chain of nucleotides, from
several to perhaps 25. The suffix "-zyme" is used to indicate an
enzyme, which usually means a large molecule that catalyzes
specific chemical reactions. In this report, the term "deoxyribo-
zyme" arises from the fact that DNA is deoxyribonucleic acid. The
term "restriction enzymes" (also called restriction endonucle-
ases) refers to a type of enzyme found in bacteria that cleaves
DNA at internal sites, the function in bacteria to destroy
bacteriophages (viruses that invade bacteria). There are hundreds
of restriction enzymes known, and each is highly specific for a
defined nucleotide sequence protected in the host bacterium. The
activity of such enzymes in bacteria is therefore "restricted" to
foreign DNA. In laboratory work using restriction enzymes,
particular fragments of DNA can be reproducibly isolated, ident-
ified, and inserted into other DNA molecules (recombination), and
restriction enzymes are important tools in recombinant DNA tech-
niques and genetic engineering. In the context of this report,
the terms "duplex" and "triplex" refer to double-stranded and
triple-stranded DNA. ... ... Carmi et al (3 authors at Yale
University, US) report a DNA structure that can cleave single-
stranded DNA oligonucleotides in the presence of ionic copper.
This "deoxyribozyme" can self-cleave or can operate as a
bimolecular complex that simultaneously uses duplex and triplex
interactions to bind and cleave separate DNA substrates. The
duplex and triplex recognition domains can be altered, making
possible the targeted cleavage of single-stranded DNAs with
different nucleotide sequences. Several small synthetic DNAs were
made to function as simple "restriction enzymes" for the site-
specific cleavage of single-stranded DNA. The authors suggest
that guided by the basic rules of duplex and triplex formation,
one can now engineer highly specific deoxyribozymes that can
catalyze the cleavage of single-stranded DNA at defined locations
along a polynucleotide chain. QY: Ronald R. Breaker, Yale
University Yale University, 203-432-4771
(Proc. Natl. Acad. Sci. US 3 Mar 98)


12. ACTION OF PEPTIDE NUCLEIC ACIDS TARGETED TO RIBOSOMAL RNA
A peptide nucleic acid is a nucleic acid analog in which the
entire phosphate sugar backbone has been replaced by an uncharged
polyamide backbone, and such molecules are known to bind to
single-stranded DNA. Ribosomal RNA (rRNA) is a class of RNA
molecules that have an important role in the structure of
ribosomes, the large molecular entities that carry out protein
synthesis in all cells. Transcription is the process by which
genetic information in DNA code is converted into RNA code, and
translation is protein synthesis, the process during which
polypeptides are synthesized on ribosomes in accordance with RNA
code. Agar plates are solidified nutrient gel plates used for
laboratory surface cultures of microorganisms. ... ... Good and
Nielsen (University of Copenhagen, DK) report that peptide
nucleic acids targeted to functional and accessible sites in
ribosomal RNA can inhibit translation in a bacterial (E. coli)
cell-free transcription/translation system, with 50% reductions
caused by nanomolar concentrations. The effect in vitro is
quantitatively similar to that of the known translation inhibitor
and antibiotic tetracycline. In addition, the targeted peptide
nucleic acids inhibited bacterial growth on agar plates and in
liquid culture. The authors suggest their results demonstrate
that ribosomal RNA is a possible target for sequence-designed
novel antibiotics based on DNA analogues or mimics.
QY: P.E. Nielsen
pen@biokemi.imbg.ku.dk
(Proc. Natl. Acad. Sci. US 3 Mar 98)

-------------------

Related Background:

TARGETED MUTAGENESIS BY PEPTIDE NUCLEIC ACIDS
... Fibroblasts are a type of connective tissue cell, secreting
structural proteins (e.g., collagen) that form certain tissue
components, including the extracellular matrix. In this report,
the term "clamp" refers to a binding of a DNA strand with a DNA
segment "clamped" between 2 segments of peptide nucleic acid. ...
... Faruqi et al (3 authors at 2 installations, US) report the
design of peptide nucleic acids to bind as clamps to a specific
chromosomal gene site in mouse fibroblasts, with an induction of
mutations 10-fold above the background. DNA sequence analysis
revealed the majority of the mutations were located within the
peptide nucleic acid binding site and the mutations consisted
mostly of single base pair insertions and deletions. The authors
suggest that the technique provides a high affinity peptide
nucleic acid clamp that constitutes a mutagenic lesion that may
provoke replication errors, and that the ability to direct 
mutations to a target site in chromosomal DNA by using peptide
nucleic acids may be a useful tool for research and therapeutic
applications. QY: Peter M. Glazer 
(Proc. Natl. Acad. Sci. US 17 Feb 98)


13. HUMAN IMMUNE SYSTEM LINKAGE TO A PLANT DEFENSE SYSTEM
Interstitial tissue is a general term for tissue forming
interstices in an organ or tissue, and "glioma" is a general term
for any neoplasm deriving from one of the various types of cells
that form the interstitial tissue of brain, spinal cord, pineal
gland, posterior pituitary gland, or retina. Glioblastoma
multiforme is a type of glioma that occurs most frequently in the
adult brain. ... ... Szyperski et al (4 authors at Institute for
Molecular Biology and Biophysics Zurich, CH) report that a human
glioma pathogenesis-related protein (GliPR), which is highly
expressed in the brain tumor glioblastoma multiforme (which
arises from brain immune cells), shows 35% amino acid sequence
identity with a tomato pathogenesis-related protein (P14a), which
has an important role for the plant defense system. The authors
compared the molecular structure of both proteins in the folded
state and identified a common partially solvent-exposed spatial
cluster of 4 amino acid residues, this cluster apparently
conserved in all known plant pathogenesis related proteins of a
particular type (called Type 1). The authors suggest their data
indicate a common active site for the human and plant proteins
and a functional link between the human immune system and a plant
defense system. In an analysis of possible evolutionary linkages,
the authors further suggest that the human immune and plant
defensive proteins considered here arose from a common ancestor
that evolved into a large pathogenesis-related protein
superfamily that includes the human protein (GliPR), plant
pathogenesis-related proteins of Type 1, mammalian sperm-coating
proteins, allergens of insect venoms, and snake or lizard toxins
-- the superfamily thus appearing in the 3 kingdoms of animals,
plants, and fungi. Although all these proteins exhibit alignment
of their amino acid sequences with the human glioma protein, the
underlying mechanism for the action of these proteins is unknown.
The authors suggest it is possible all the proteins of this
superfamily operate according to the same molecular mechanism.
QY: K. Wuethrich, Institut fur Molekularbiologie und Biophysik,
Eidgenoessische Technische Hochschule-Hoenggerberg, CH-8093
Zurich, CH (Proc. Natl. Acad. Sci. US 3 Mar 98)

(continued in Part 3)

=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=

SCIENCE-WEEK - Part 3/3

A Free Weekly Digest of the News of Science

March 27, 1998

Contents of Part 3:

14. CALCIUM SENSING OF METABOTROPIC GLUTAMATE RECEPTORS
15. A MUSCLE CELL TROPHIC FACTOR THAT INCREASES INNERVATION
16. EVIDENCE FOR HUMAN WATERCRAFT 800,000 YEARS AGO
17. INVOLVEMENT OF E-CADHERIN IN ADENOMA TO CARCINOMA TRANSITION
18. NOTED EPIDEMIOLOGIST W.M. HAENSZEL DEAD AT 87

----------------------------------------------------------------

14. CALCIUM SENSING OF METABOTROPIC GLUTAMATE RECEPTORS
L-glutamate (derived from the amino acid, glutamic acid) is
considered the principal excitatory neurotransmitter in the
vertebrate central nervous system, and is one of the neuro-
transmitter substances that interact with ion channels that are
switched on or off by specific ligands (i.e., they are "ligand-
gated"). Glutamate is known to act on 3 classes of receptors, one
of which is a slow-acting receptor type coupled to G-proteins and
called "metabotropic". (The G-proteins are membrane-bound
proteins that act as transducers between messenger molecules
interacting with the cell surface and the intracellular messenger
system). Frog oocytes are frog egg cells, and they are a common
laboratory vehicle for expressing the proteins of genetically
engineered material from other species and coupling this
expression with electrophysiological measurements of frog oocyte
membrane behavior. "Transfection" is the uptake of exogenous
(foreign) DNA fragments in solution directly into animals cells
in laboratory culture, and is one method of introducing foreign
genes into cells. ... ... Kubo et al (3 authors Tokyo
Metropolitan Institute for Neuroscience, JP) report
investigations of the behavior of rat metabotropic glutamate
receptors as calcium ion sensors in a frog oocyte expression
system, and that some types of these receptors are indeed
activated not only by glutamate but also by extracellular
Ca(sup2+). A single amino acid residue was found to determine the
sensitivity of these receptors to calcium ion, and one of the
receptors caused morphological changes when transfected into
mammalian cells. The authors suggest that in cells under
physiological conditions, the sensing of extracellular calcium
ion by metabotropic glutamate receptors may be an important
aspect of neuron cell regulatory processes.
QY: Yoshihiro Kubo 
ykubo@tmin.ac.jp (Science 13 Mar 98)

-------------------

Related Background:

SECRETION OF GLUTAMATE BY BRAIN ASTROCYTES
Glial cells are more numerous than neurons in the brain, but
their function has been generally characterized as "metabolic" or
"supportive", without much discussion of details, and more is
known about peripheral glial cells than glial cells in the
central nervous system. Astrocytes are the largest glial cells,
with many extensions radiating outward like a starburst, and at
least one of their functions is apparently to maintain the so-
called "blood-brain barrier" effectively separating neural tissue
from blood. ... Kainic acid, an algal neurotoxin, is a structural
analogue of glutamate, and it has been extensively used in
research, since at high concentrations it selectively destroys
glutamate receptor neurons (glutaminergic neurons). Glutamate is
known to act on 3 classes of receptors, one of them called the
kainate receptor because at low concentrations of kainic acid the
action of glutamate on this receptor is enhanced. The chemistry
of this kainate receptor is not yet well-characterized, mainly
because selective ligands for it are not known. Another class of
glutamate receptor is the AMPA receptor [AMPA = (RS)-alpha-amino-
3-hydroxy-5-methyl-4-isoxazoleproprionic acid], and the third is
NMDA (N-methyl-D-aspartate). These 3 receptors are ionotropic,
i.e., their activation produces changes in membrane ion permeab-
ility. According to another and more recent scheme of glutamate
receptor classification, one receptor type is AMPA/kainate
(ionotropic), another receptor type is NMDA (ionotropic), and a
third receptor type is a slow-acting receptor type coupled to G-
proteins and called metabotropic receptors. (The G-proteins are
membrane-bound proteins that act as transducers between messenger
molecules interacting with the cell surface and the intracellular
messenger system). Prostaglandins are fatty acids secreted by
cells that have hormone-like actions in the immediate vicinity,
and one circumstance that produces their release is tissue
injury. ... ... Bezzi et al (8 authors at 2 installations, IT)
report that coactivation of the AMPA/kainate and metabotropic
glutamate receptors on astrocytes stimulates these cells to
release glutamate through a calcium-dependent process mediated by
prostaglandins. The authors suggest their results reveal a new
pathway of regulated transmitter release from astrocytes, and
that interactions between neurons and astrocytes may play a
critical role in synaptic plasticity and neurotoxicity. They also
suggest that the prostaglandin-mediated glutamate release from
astrocytes may be involved in the pathophysiology of various
brain diseases and injuries.
QY: Andrea Volterra  (Nature 15 Jan 98)


15. A MUSCLE CELL TROPHIC FACTOR THAT INCREASES INNERVATION
The term "overexpression" in this report refers to a greater than
normal genome-coded synthesis of a protein. Glial cells are the
cells of the central and peripheral nervous systems that produce
the multiple membrane layers called myelin and enfold nerve cell
axons with it. A "neurotrophic factor" is a polypeptide molecule
that supports the survival of specific populations of nerve cells
via specific signal-transducing cell receptors. Motor neurons are
neurons of the central nervous system that connect to and excite
muscle cells, and motor axons are the extensions of these motor
neurons that innervate (i.e., connect to) the muscle cells. The
specialized junction between the motor neuron axon terminal and
the muscle cell is called the "neuromuscular junction". The
"neurotrophin family" is a family of known proteins whose
presence is necessary for the survival of various classes of
neurons: in the absence of neurotrophins, specific types of
neurons undergo programmed cell death (apoptosis). ... ... Nguyen
et al (4 authors at Washington University St. Louis, US) report
that overexpression of a glial cell line-derived neurotrophic
factor (called GDNF: Glial-Derived-Neurotrophic-Factor) by muscle
cells greatly increases the number of motor axons innervating
neuromuscular junctions in neonate mice, with the extent of
hyperinnervation correlated with the amount of the protein
expressed. The authors suggest that increased amounts of GDNF in
postsynaptic target cells can regulate the number of innervating
axons, and that this synaptic plasticity involves mediation by a
growth factor outside the recognized neurotrophin family. QY:
Jeff W. Lichtman (jeff@thalamus.wustl.edu)
EMAIL
(Science 13 Mar 98)


16. EVIDENCE FOR HUMAN WATERCRAFT 800,000 YEARS AGO
The term "fission-track dating" refers to a method of dating
geological specimens by counting the radiation-damage tracks
produced by spontaneous fission of uranium impurities in minerals
and glasses, and in this report zircon grains were used as the
dating material to date stone tools. The islands of Wallacea are
located between Southeast Asia and Australia, east of Java and
Bali, and investigations of extant animal species and animal
fossils on the Wallacean island of Flores indicate this island
was not land-connected to ancient Southeast Asia (called Sunda)
during approximately the past 1 million years, or perhaps even
before that. Homo erectus is considered the second species of the
human genus Homo to evolve. H. erectus used fire and stone tools,
appeared in Africa about 1.7 million years ago, and evidently
migrated throughout Eurasia. The species disappeared from Africa
approximately 500,000 years ago, and from Asia about 250,000
years ago. The Pleistocene is the geological time period from
about 2 million years ago to about the end of the last glaciation
about 10,000 years ago. Modern man is believed to have evolved
during the Pleistocene. ... ... Morwood et al (3 authors at 3
installations, AU ID) report zircon fission-track dating of
material from two fossil sites on the Wallacean island of Flores,
the fossil sites now and at the time of the dated material
reachable only by water crossings from Southeast Asia. The data
indicate that Homo erectus in this region, in the period 800,000
to 900,000 years ago, was capable of repeated water crossings
using watercraft. The authors suggest this evidence, combined
with the geographical radiation of Homo erectus in the Early
Pleistocene and other recent discoveries, indicates the cognitive
capabilities of this species may be due for reappraisal. QY: M.J.
Morwood (mmorwood@metz.une.edu.au)
EMAIL
(Nature 12 Mar 98)


17. INVOLVEMENT OF E-CADHERIN IN ADENOMA TO CARCINOMA TRANSITION
Cell adhesion is simply the ability of cells to remain in
association with each other, and one of the characteristics of
cancer cells is that they lose this ability and become free-
roaming. E-cadherin (also called uvomorulin) is a transmembrane
protein that links plasma membranes of adjacent cells together,
and thus aids in maintaining the rigidity of a cell layer. In
animals, epithelial cells compose the cell layers that form the
interface between a tissue and the external environment, for
example, the cells of the skin, the lining of the intestinal
tract, and the lung airway passages, and an adenoma is an
ordinarily benign neoplasm of epithelial tissue in which the
tumor cells form glands or gland-like structures that are usually
circumscribed and do not invade other tissues. The term
"carcinoma" refers to any of the various types of malignant
neoplasms derived from epithelial tissue, and one of the
characteristics of many carcinomas is that they involve a
progression from a benign adenoma to a malignant tumor. A
transgenic mouse is a mouse into which genetic material from
another organism has been transferred, the transferred and
incorporated new mouse genes then being expressed with the
resultant production of specific proteins. The beta-cells of the
pancreas are the predominant cells of the pancreas region that
secretes the hormone insulin. ... ... Perl et al (5 authors at 2
installations, AT SE) report that the loss of E-cadherin
expression coincides with the transition from well-differentiated
adenoma to invasive carcinoma in a transgenic mouse model of
pancreatic beta-cell carcinogenesis. The authors suggest their
results demonstrate that loss of E-cadherin-mediated cell
adhesion is one rate-limiting step in the progression from
adenoma to carcinoma, and that unraveling the regulation of E-
cadherin expression and its relation to cell adhesion may lead to
a better understanding of how tumor cells control their invasive
characteristics.
QY: Gerhard Christofori (christofori@nt.imp.univie.ac.at)
EMAIL
(Nature 12 Mar 98)


18. NOTED EPIDEMIOLOGIST W.M. HAENSZEL DEAD AT 87
William M. Haenszel, epidemiologist at the US National Cancer
Institute, died on March 13th in home in Wheaton, Il (US) at the
age of 87. Haenszel designed and set up the first national system
to track cases of cancer and their possible causes, the system
called SEER (Surveillance, Epidemiology, End-Results), and it was
this system that helped produce evidence of the links between
smoking and lung cancer. The SEER system, initiated in 1973, is
considered the largest registry for a single disease in the
world. Haenszel was also known for migrant studies in the 1950s
and 1960s demonstrating that high stomach cancer rates in Japan
were no longer found in the Japanese who migrated to Hawaii, thus
identifying the role of diet as a possible cause of stomach
cancer. Haenszel was a professor of epidemiology at the
University of Illinois (US) for many years.
(New York Times 22 Mar 98)

---------------------------------------------

BOOK NOTES:

H.A. Bachor: A GUIDE TO EXPERIMENTS IN QUANTUM OPTICS
Wiley, 1998, 300p, US70 CA98.50
Attempts to bridge the gap between theory and experiment.
Classical properties of light, models for the quantum properties
of light, basic components of experiments, quantum optics
experiments, nonclassical light and squeezing.

P. Esquinazi (ed.): TUNNELING SYSTEMS IN SOLIDS
Springer, 1998, 600p, US89
A discussion of key experiments and latest theories of tunneling
in solids, particularly at low temperatures. Introductory survey,
details on relevant experiments and new theories, ideas on
current research directions. 

Henning Genz: NOTHINGNESS
The Science of Empty Space
Addison-Wesley, 1998, 368p, US30
A nontechnical discourse on empty space by a theoretical
physicist. Metaphysical speculations of the ancient Greek
philosophers, theories of Newton, theories of quantum physics and
cosmology. 

J. Gregory and S. Miller: SCIENCE IN PUBLIC
Communication, Culture, and Credibility
Plenum, 1998, 300p, US29.95
A survey of the relations between scientists and the public and
the public attitude towards science and scientists. A synthesis
of the ideas of historians, sociologists, psychologists,
journalists, politicians, educators, and communications
researchers on the theory and practice of science politics. Pros
and cons on popular science, science and the mass media, case
studies in public science, science in museums, communication
protocols. The authors are science journalists.

Michael Gross: LIFE ON THE EDGE
Amazing Creatures Thriving in Extreme Conditions
Plenum, 1998, 250p, US25.95
An account of extremophilic organisms in hostile Earth habitats.
Biochemical survival strategies, significance for biotechnology,
medicine, the search for extraterrestrial life. The author is a
molecular biologist at Oxford Univ., UK.

T. Ishiguro and K. Imaji: ORGANIC SUPERCONDUCTORS 
Second Edition
Springer, 1998, 288p, US54
An introduction to organic conductors and superconductors.
Structure and electronic properties, theories of
superconductivity, spin-density waves, design and synthesis,
latest research.

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