ScienceWeek

SCIENCE-WEEK

A Weekly Email Digest of the News of Science

A journal devoted to the improvement of communication
between the scientific disciplines, and between scientists,
science educators, and science policy makers.

May 7, 1999 -- Vol. 3 Number 19

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

Geological time inspires awe, and there are no
certainties about the future, but perhaps it is
almost certain that someday they will collect
our skulls and call us Early Man.
-- Anonymous

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

From the Editors:
With this issue, ScienceWeek begins its 3rd year of publication.
The Editors extend their gratitude to all our subscribers for
their continuing financial support and intensive encouragement.
Financial support may help pay the rent here, but it is your
encouragement that has provided the psychological energy that
keeps us going. We thank all of you for it.

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

Contents of This Issue:

1. On AIDS, Drugs, Patents, and Responsibilities
2. On Stellar Evolution
3. Biogenesis: UV Production of Alcohols, Quinones, and Ethers
4. A Processive Single-Headed Motor Protein
5. 3-Dimensional Structure of a Gap Junction Membrane Channel
6. Parkinson's Disease in Twins: An Etiological Study

In Focus: On Max Planck

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

Please note:
On August 1, 1999 the subscription rate for ScienceWeek
will increase to $20 per year (52 issues). For substantial
savings, renew or extend your subscription now for 1 or more
years at the current rate. Subscription information is
available at URL http://scienceweek.com/subinfo.htm
or see the information in the Notices section below.

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

1. ON AIDS, DRUGS, PATENTS, AND RESPONSIBILITIES
The general philosophical question concerning epidemics and drugs
and profits is simply stated: If 25 million people in
underdeveloped countries are being ravaged by an epidemic of a
lethal disease, and pharmaceutical firms in developed countries
have in their hands one or more drugs established as effective in
the prevention or treatment of that disease, and if the current
prices for these drugs make them unaffordable in the
underdeveloped countries, what is to be done? There is perhaps no
clearer entanglement of basic research, applied science, and
commercial interests than the above question as it concerns the
current international AIDS epidemic. An important conflict in the
pharmacotherapeutic arena is developing, one which may set the
pattern for future interactions between pharmaceutical companies
and governments. The essentials of the conflict are as follows:
The pharmaceutical industry, with the assistance of the US
government, is fighting efforts to make cheaper generic versions
of AIDS drugs available to the underdeveloped countries currently
being ravaged by the AIDS epidemic. The drug firms wish to
maintain exclusive control of the manufacture and marketing of
their patented AIDS drugs, but some countries are issuing to
local firms licenses that allow production of affordable generic
versions of these drugs. ... ... Merrill Goezner (Chicago
Tribune, US) presents a review of the conflict, the author making
the following points: 1) Although the World Trade Organization
guards intellectual property rights among its member nations, its
rules of trade do allow for compulsory licensing in the case of
national emergencies. Thus South Africa, with more than 3 million
HIV cases, and one-fourth of pregnant mothers in the poorest
provinces HIV-positive, recently passed a compulsory licensing
law that apparently meets the World Trade Organization national
emergency guidelines, the law allowing licenses to local firms to
manufacture low-cost generic versions of patented anti-AIDS
drugs. 2) The South African law, however, has evidently angered
the US pharmaceutical industry, which apparently fears the
widespread licensing of its products will lead to a global "gray
market" in low-priced drugs, a gray market that will undermine
its profits and incentive to invest in costly research. 3) The US
pharmaceutical industry has therefore pressured the US government
to take action against the South African law. Legislation has
been introduced in the US Congress, and US trade representatives
are actively applying pressure in South Africa to have the
compulsory licensing law repealed. So far, South Africa has
refused. 4) Meanwhile, the pharmaceutical industry in both the US
and Europe has taken a firm position: Thomas Bombelles of the
Pharmaceutical Research and Manufacturers Association says
compulsory licensing is "a form of patent piracy... It's
stealing." 5) When used in a treatment regimen, the drug AZT,
manufactured by Glaxo-Wellcome, a drug that has proved effective
in inhibiting transmission of HIV from pregnant women to their
fetuses, costs approximately US$240 a month in South Africa when
purchased from Glaxo-Wellcome. Indian drug firms manufacture a
generic version of the drug that costs US$48 a month. The issues,
it seems, are clear.
-----------
Merrill Goezner: Third World battles for AIDS drugs.
(Chicago Tribune 28 Apr 99)
QY: Merrill Goezner, Chicago Tribune, 435 N. Michigan Ave.,
Chicago, IL 60611 US.
-------------------
Summary by SCIENCE-WEEK [http://scienceweek.com] 7May99
-------------------
Related Background:
ESTIMATED 20 MILLION INFECTED WITH AIDS IN SUB-SAHARAN AFRICA
There is perhaps too much of a tendency in many quarters to think
of a plague only as a state of affairs in which people drop dead
in expensive restaurants and get hauled away in trucks containing
piles of bodies. Our current plague, although not as dramatic as
some plagues of the past, is no less an international calamity. 
The United Nations AIDS Program recently released a report
containing the following: 
-- In 1997, 5.8 million people worldwide were newly infected with
HIV.
-- The number of new HIV infections this year rose 9% over 1996.
-- The total number of infected adults is now a little under 30
million, about 1% of the world's adult population.
-- This year, the total number of people infected with HIV
increased by 13%
-- More than 20 million people in sub-Saharan Africa are infected
with HIV, which is 7% of that adult population.
-- This year, 2.3 million people worldwide will have died of
AIDS, the consequent stage of HIV infection.
-- In South and Southeast Asia, 6 million people are infected
with HIV.
-- In Latin America, 1.3 million people are infected with HIV.
-- In North America, 860,000 people are infected with HIV.
-- In Western Europe, 150,000 people are infected with HIV.
(Nature 27 Nov 97) (Science-Week 19 Dec 97)
-------------------
Related Background:
MAJOR DRUG COMPANIES REFUSE ANTI-MALARIA COLLABORATION
An anti-malaria joint effort originally designed by the Wellcome
Trust, the World Health Organization, the World Bank, the
Association of the British Pharmaceutical Industry, and the drug
companies Roche and Glaxo-Wellcome has apparently disintegrated
as a result of a decision of the pharmaceutical interests not to
support it. The idea was to gather US$180 million for a joint
project to develop new treatments for the world's most
threatening tropical diseases, particularly for malaria. Now the
pharmaceutical industry leaders say, "There are drugs and
vaccines for malaria already in development within the
pharmaceutical industry." Malaria researchers have expressed
their disappointment. Brian Greenwood (London School of Hygiene
and Tropical Medicine) says, "We really thought industry was
wanting to help." (Science 5 Dec 97)
-------------------
Related Background:
INERTIA IN INTERNATIONAL EFFORTS TO CURB MALARIA
Malaria, an infectious disease caused by a parasitic protozoan
transmitted by a mosquito bite, blood transfusion, or the use of
a common syringe by drug addicts, kills one or two million people
each year. There are actually 4 types of protozoan parasites that
cause the disease, with Plasmodium falciparum the most dangerous.
The drug chloroquine is quite effective, except with P.
falciparum, which is usually resistant to it. Treatment of
falciparum malaria requires the administration of a number of
drugs simultaneously and close technological monitoring of the
patient. Falciparum malaria is hyperendemic in East Africa,
Central and South America, and the Far East, and if untreated it
has a high fatality rate. Attempts by the international community
to control malaria have been underway for many decades. In
January there was another meeting of the scientific community
involved with the disease. Last week in The Hague (NL), there was
another meeting of high-level government officials, foundation
managers, and pharmaceutical company representatives. The
apparent consensus was that we cannot collaborate because we
don't know how, and even if we did collaborate, we cannot
manufacture the old drugs or new drugs or possible vaccines
because the people who need them cannot afford them and there is
thus no market of commercial interest. Everyone agreed to meet
again, perhaps in six months.
(Science 18 Jul 97) (Science-Week 25 Jul 97) 


2. ON STELLAR EVOLUTION
In astronomy, the Hertzsprung-Russell diagram (H-R diagram) is a
2-dimensional graph of the correlation between the spectral type
of stars (i.e., their temperature) and the luminosity of stars.
The diagram was formulated independently by E. Hertzsprung in
1911 and H.N. Russell in 1913. Instead of uniform distributions
of stars on such a diagram, what is found is that for any large
sample of stars well-defined groups or bands of stars occur on
the graph. Approximately 90 percent of stars lie along a diagonal
band known as the "Main Sequence"; the somewhat brighter *giant
stars form another sequence; the very brightest and relatively
rare "*supergiants" form still another sequence; and also
distinguishable are *white dwarfs and other groupings.
Essentially, the life history of a star can be traced as movement
along a particular path in the H-R diagram, and the diagram is of
considerable importance in studies of stellar evolution, since
diagrams obtained by theoretical calculations can be tested
against H-R diagrams determined by observation.
... ... James B. Kaler (University of Illinois Urbana-Champaign,
US) presents a detailed review of stellar evolution, the author
making the following points concerning the Hertzsprung-Russell
diagram: 1) The huge variety of Main-Sequence stars results from
the differences in their masses. The mass range is from nearly
100 times the mass of the Sun to 0.08 solar-mass for the dimmest
of *red dwarf stars. 2) A star spends most of its life on the
Main Sequence until its hydrogen fuel begins to be exhausted.
Since the larger stars burn fuel more rapidly, the most massive
and luminous stars remain on the Main-Sequence for a few million
years, while the smallest dwarf stars remain on the sequence for
trillions of years. 3) Although Main Sequence stars are extremely
stable, they do change. The Sun, for example, has apparently
increased its brightness by approximately 30 percent since its
birth 4.6 billion years ago. 4) Nearly all non-Main Sequence star
types result from the stellar aging process, the characteristics
of which depend primarily on stellar mass [*Note #1]
-----------
Editor's note: For an explicative text, see the SW Focus Report
"The Death of Stars" available at URL
http://scienceweek.com/swfr.htm
-----------
James B. Kaler: Eyewitness to stellar evolution.
(Sky & Telescope March 1999)
QY: James B. Kaler [http://www.astro.uiuc.edu/~kaler]
-----------
Text Notes:
... ... *giant stars: Giant stars represent a late phase in
stellar evolution, when the central hydrogen supply has been
exhausted and the star is burning other nuclei in concentric
shells near its core. Despite their great size (as large as the
entire inner Solar System), these stars are not necessarily more
massive than typical Main-Sequence stars: they have dense central
cores, but their atmospheres are extremely tenuous.
... ... *supergiants: Supergiant stars, which may be as large as
the entire Solar System, are extremely rare. Examples of
supergiant stars are Rigel and Betelgeuse in Orion, and Antares
in Scorpius.
... ... *white dwarfs: White dwarf stars are extremely dense
and compact stars that have undergone gravitational collapse.
They are the final stage in the evolution of low-mass stars after
they have lost their outer layers. White dwarf stars are about
the size of Earth, but with a mass about that of the Sun.
... ... *red dwarf stars: Red dwarf stars are much cooler,
smaller, and less massive than the Sun (approximately 0.1 to 0.7
solar-mass).
... ... *Note #1: Our present models of the fate of stars have
come about during the past 50 years primarily as a result of the
conjunction of three factors: 1) a flood of spectroscopic data
concerning the chemical composition of stars; 2) the development
of a detailed understanding of the atomic physics and
thermodynamics of nuclear fusion 3) the growing availability of
powerful computers to solve computational problems that were
previously intractable. The remnant mass after the blow-off of
its outermost shells during the terminal stage of the life of a
star determines the ultimate fate of the star. If the remnant
mass is less than 1.44 solar masses (the Chandrasekhar limit for
a star with no hydrogen content), the star collapses into a white
dwarf. If the remnant mass is greater than 1.44 solar masses,
depending on the remnant mass, the star collapses into either a
neutron star or a black hole. (The Chandrasekhar limit is named
after Subrahmanyan Chandrasekhar (1910-1995), who first proposed 
the modern theory of stellar gravitational collapse, and who
received the Nobel Prize in Physics 1983.)
-------------------
Summary & Notes by SCIENCE-WEEK [http://scienceweek.com] 7May99


3. BIOGENESIS: UV PRODUCTION OF ALCOHOLS, QUINONES, AND ETHERS
The local interstellar medium is the interstellar matter between
objects in our Galaxy, and consists primarily of clouds of
interstellar gas and a small density of interstellar dust grains.
Infrared spectroscopy of the interstellar medium, combined with
laboratory studies of realistic interstellar analogs is a method
of identifying the matter that exists between the stars. The
interstellar medium is known to contain a variety of grains,
including silicates, carbon-rich particles, and ices, and a large
number of gas-phase species. The most abundant and widespread of
the carbon-carrying gaseous species is believed to be the class
of polycyclic aromatic hydrocarbons. In dense molecular clouds,
where optical depths are high and the ambient radiation field of
the Galaxy is screened, temperatures are low (e.g., less than 50
degrees kelvin). Under these conditions, most gaseous species
condense in the form of mixed-molecular ices containing a variety
of molecular species, the most abundant of which is water.
Laboratory studies and astronomical observations have
demonstrated that radiation processing of these ices modifies
them and creates more complex molecular species.
... ... M.P. Bernstein et al (6 authors at 3 installations, US)
report a study of polycyclic aromatic hydrocarbons in water ice
exposed to ultraviolet radiation under astrophysical conditions,
with analysis of the products by infrared spectroscopy and *mass
spectrometry. The authors report both oxidation and reduction of
peripheral carbon atoms occurred, oxidation producing aromatic
alcohols, ketones, and ethers, and reduction producing partially
hydrogenated aromatic hydrocarbons. The authors point out that
these classes of compounds are all present in *carbonaceous
meteorites. The authors suggest that some of the molecules
produced in their experiments are biologically relevant and might
help establish the primordial boundary conditions of the origin
of life. Examples are the produced quinones (essential for
electron transport in simple organisms) and aromatic alcohols
(which can partition into and modify the properties of lipid
bilayer membranes). The authors conclude: "The inventory of
organics that fell on early Earth was complex and should not be
considered simply a source of reduced carbon for terrestrial
processes to alter before incorporation into the first living
organisms."
-----------
M.P. Bernstein et al: UV irradiation of polycyclic aromatic
hydrocarbons in ices: Production of alcohols, quinones, and
ethers.
(Science 19 Feb 99 283:1135)
QY: Max P. Bernstein [mbernstein@mail.arc.nasa.gov]
-----------
Text Notes:
... ... *mass spectrometry: The mass spectrometer is a
device in which molecules are ionized and the accelerated ions
are separated according to their mass to charge ratio. The
relative abundance of isotopes or other ionized species can thus
be determined by measuring positive or negative ion currents.
... ... *carbonaceous meteorites: (carbonaceous chondrites)
"Stony" meteorites (aerolites) are meteorites formed solely of
rock-forming silicates, and chondrites are a type of stony
meteorite consisting of an agglomeration of millimeter-sized
globules (chondrules) that are thought to be unchanged since the
original condensation out of the nebula from which the sun and
solar system formed. A "carbonaceous meteorite" is a chondritic
meteorite that contains a relatively large amount of carbon, with
a resultant dark appearance.
-------------------
Summary & Notes by SCIENCE-WEEK [http://scienceweek.com] 7May99
-------------------
Related Background:
ON CARBON IN THE UNIVERSE
Carbon is a major factor in the evolutionary scheme of the
Universe because of its abundance and its ability to form complex
chemical entities. It is apparently also a key element in the
evolution of prebiotic molecules. The different forms of cosmic
carbon range from carbon atoms and carbon-bearing molecules to
complex solid-state carbonaceous structures, and evidence
gathered during the past decade has considerably enhanced our
understanding of the physical and chemical properties of carbon
materials in space. ... ...  Th. Henning and F. Salama (2
installations, DE US) present a detailed review of the subject,
the authors making the following points: 1) More than 75 percent
of the 118 *interstellar and circumstellar molecules identified
to date are carbon-bearing molecules, and one component of
interstellar dust is evidently carbonaceous. The cosmic evolution
of carbon from the interstellar medium into *protoplanetary disks
and *planetesimals, and finally into habitable bodies, is
intrinsic to the study of the origin of life. 2) Carbon plays an
important role in the physical evolution of the interstellar
medium because it is the main supplier of free electrons in
diffuse interstellar clouds, thus contributing to the heating of
interstellar gas. 3) The observation of unidentified ubiquitous
molecular and solid-state features in astronomical spectra, and
the realization that these features are linked to carbonaceous
materials, have resulted in major scientific progress in the past
decade. Laboratory and theoretical studies stimulated by these
astronomical observations have led to a better understanding of
the various forms of cosmic carbon such as polycyclic aromatic
hydrocarbons, carbon-chain molecules, carbon clusters, and
carbonaceous solids. These investigations have also led to the
detection of novel forms of carbon and laid the foundations for
the chemistry of *fullerenes. 4) The authors present the
following categorization of carbon in space:
... a) Carbon-rich circumstellar envelopes around *red giant and
*asymptotic giant branch (AGB) stars: CO, C(sub2)H(sub2), complex
hydrocarbons, gas-phase polycyclic aromatic hydrocarbons.
... b) Diffuse interstellar medium: C+, simple diatomic
molecules, gas-phase polycyclic aromatic hydrocarbons and carbon
chains.
... c) Dense interstellar medium: CO, complex hydrocarbons.
... d) Interstellar material in primitive meteorites: polycyclic
aromatic hydrocarbons.
5) The authors suggest that the widespread distribution of
complex organics in the interstellar medium has profound
implications for our understanding of a) the chemical complexity
of the interstellar medium, b) the evolution of prebiotic
molecules, c) the impact of this evolution on the origin and
evolution of life on early Earth through the exogenous delivery
(by cometary encounters and meteoritic bombardments) of prebiotic
organics.
-----------
Th. Henning and F. Salama: Carbon in the Universe.
(Science 18 Dec 98 282:2204)
QY: Th. Henning, Astrophysikalisches Institut und Universitats-
Sternwarte, Schillergabchen 2-3, D-07745, Jena DE.
-----------
Text Notes:
... ... *interstellar and circumstellar molecules: In this
context, an interstellar molecule is any molecule that occurs
naturally in clouds of gas and dust in space. In general, a
circumstellar molecule is any molecule that occurs in gas and
dust surrounding a star.
... ... *protoplanetary disks: These are dust disks surrounding
young stars; it is from these disks that planets presumably form.
... ... *planetesimals: Planetesimals are bodies with dimensions
of 10^(-3) to 10^(3) meters that are believed to form planets by
a process of accretion. The term "accretion" refers to an
aggregation, an increase in the mass of a body by the addition of
smaller bodies that collide and adhere to it, provided the
relative velocities are low enough for coalescence. As the mass
of the agglomerate increases, so does the rate of accretion, and
this accretion process is believed to generally occur in the form
of a disk. A stellar accretion disk is a swarm of dust grains
that evolve into planetesimals and then planets.
... ... *fullerenes: Fullerenes are large molecules composed
entirely of carbon, with the chemical formula C(sub n), where n
is any even number from 32 to over 100. They apparently have the
structure of a hollow spheroidal cage with a surface network of
carbon atoms connected in hexagonal and pentagonal rings.
... ... *red giant: A red giant star is a star in a late
stage of evolution. Having exhausted the hydrogen fuel in its
core, the star is burning elements heavier than hydrogen. It has
a surface temperature of less than 4700 degrees Kelvin and a
diameter 10 to 100 times that of the Sun.
... ... *asymptotic giant branch (AGB) stars: These are stars
that occupy a strip in the *Hertzsprung-Russell diagram that is
almost parallel to and just above what is called the "giant
branch" off the *Main Sequence. Stars evolve from the horizontal
H-R branch to the asymptotic giant branch when they have
exhausted the helium in their cores and are instead burning
helium in a shell.
... ... *Hertzsprung-Russell diagram: The Hertzsprung-Russell
diagram is a plot of stellar absolute magnitude against spectral
type, and is perhaps the most useful diagrammatic aid in
astrophysics. It allows the portrayal of the evolution of a star
as occurring along various paths in the diagram.
... ... *Main Sequence: The Main Sequence is a region on the
Hertzsprung-Russell diagram where most stars lie, including our
own Sun. The evolution of a star can be diagrammed as a movement
along the Main Sequence and an eventual branching off the Main
Sequence to regions associated with various types of old stars.
-------------------
Summary & Notes by SCIENCE-WEEK [http://scienceweek.com] 26Feb99
-------------------
Related Background:
ORIGIN OF LIFE: THE PRESENT STATUS OF CHEMICAL THEORY
The essential question involved in the origin of what we call
life is how can order arise from disorder? At the present time,
this question is approached on two fronts: 1) study of the
principal features of self-organizing systems, systems in which
order does arise from disorder, systems in which order is indeed
demanded from disorder on thermodynamic grounds; and 2) study of
the detailed chemistry of such systems, the chemistry of
organization and the chemistry of components. In the case of
components, it is essential that appropriate self-organizing
components exist in the first place if they are to become self-
organized, and such candidate components are thus the focus of
much chemical research in this area. In 1953, the chemist Stanley
Miller reported what soon became a famous experiment. To water
under a gas mixture of methane, ammonia, and hydrogen, he added
an electrical discharge. After one week of continuous electrical
discharge, he found that a number of important biological
molecules, including amino acids, had been formed. Miller
proposed his experiment as a model for the conditions under which
the essential compounds necessary for life originated . The
Miller experiment was a watershed, and it began a new era of
experimentation and analysis of possible primordial components.
Coupled with this, were the new important discoveries by
astrophysicists of the presence of organic molecules in the
interstellar medium and in meteorites. In a review of origin of
life theories, P. Radetsky (Univ. of California Santa Cruz, US)
points out that the Miller theory is no longer the consensus
theory, that contemporary geologists believe the primordial
atmosphere consisted primarily of carbon dioxide and nitrogen,
which are less reactive than the gases in the Miller experiment,
and that the field is currently embroiled in controversy fueled
for the most part by an absence of hard fact.
-----------
QY: Peter Radetsky, Univ. of California Santa Cruz 408-429-4008
(Earth February 1988) (Science-Week 2 Jan 98)
-------------------
Related Background:
ANALYSIS OF DUST REMNANTS OF THE SOLAR NEBULA
Chondrites are a type of stony meteorite consisting of an
agglomeration of millimeter-sized globules (chondrules) that are
thought to be unchanged since the original condensation out of
the nebula from which the sun and solar system formed. Presolar
grains are grains less than 1 micron in diameter found in
chondrites (thus smaller than chondrules) that have anomalous
isotope concentrations. Cosmic rays, which consist mainly of the
nuclei of atoms, are high-energy atomic particles that enter the
Earth's atmosphere from space. The nuclides are the various fin-
ite lifetime (e.g., > 10^(-10) seconds) nuclear species of any
particular atom, such as the finite lifetime isotopes of an atom.
The local interstellar medium is the interstellar matter between
objects in our galaxy, and consists primarily of clouds of
interstellar gas and a small density of interstellar dust grains.
... ... Bernatowicz and Walker (Washington Univ., St. Louis US)
review the past several decades of research concerned with the
properties of presolar grains found in chondrite meteorites. The
authors suggest that the integration of such data with emerging
information on the isotopic properties of high-energy and
low-energy cosmic rays that sample the local interstellar medium
should provide deeper insights into the production and evolution
of nuclides.
-----------
QY: Thomas Bernatowicz, Washington Univ. St. Louis, Dept. of
Physics 314-935-6250
(Physics Today December 1997) (Science-Week 12 Dec 97)


4. A PROCESSIVE SINGLE-HEADED MOTOR PROTEIN
In biological cells, orchestrated movements of intracellular
macromolecules are essential for a number of important phenomena,
including various transport processes and cell division.
"Microtubules" are part of the cytoskeleton of biological cells,
the quasi-rigid matrix that among other things determines cell
shape. The microtubules are 25 nanometers in diameter, and
composed of the protein tubulin. They occur in regular arrays in
various motile structures (e.g., *cilia, *flagella, *mitotic
spindle), and in the cytoplasm in general, and they contribute
not only to cell shape, but also to cell movements.
"Microfilaments" are 4 to 6 nanometers in diameter, highly
variable in length, and are found in all eukaryotic cells (cells
with internal membrane-bound compartments such as a nucleus).
They are composed of a protein called "actin" and several other
accessory proteins, and they are important in cell locomotion and
in the molecular dynamics of muscle cells. "Motor proteins" are
mechanico-chemical enzymes involved in locomotion of cells or
transport of materials in cells, and there are three families of
such proteins: kinesins, dyneins, and myosins. Kinesins and
dyneins are microtubule based motor proteins, while myosin is a
microfilament based motor protein. In general, as mechanico-
chemical enzymes, motor proteins convert energy from hydrolysis
of nucleotides to mechanical force, and since they are involved
in many important cellular events, the molecular details are
currently the focus of intensive research. An ordinary single
kinesin molecule has two "heads" or motor domains and moves
processively, i.e., without intermittent complete detachment from
its associated microtubule. Thus, a single kinesin molecule can
take more than 100 steps (over a microtubule length of more than
1 micron) before detaching from the microtubule. The 2-headed
structure is assumed to be essential for processive movement,
since engineered single-headed or monomeric molecules have motor
activity but are not processive, whereas dimeric engineered
molecules have high processivity. The prevailing hypothesis for
the mechanism of processive movement is the "walking model", in
which one head anchors the molecule to the microtubule while the
other head moves to the next binding site on the microtubule.
Thus, a single-headed molecule is not expected to move
processively because the molecule is not anchored while it moves
to the next binding site. ... ... Y. Okada and N. Hirokawa
(University of Tokyo, JP) now report a motor-domain construct
(i.e., engineered entity) of a single-headed kinesin protein
(kinesin superfamily protein KIF1A) which apparently moves
processively along an associated microtubule for more than 1
micron. The authors report analysis indicates this movement is
essentially a random process and fits a biased Brownian movement
model (i.e, diffusion with a drift). The authors conclude: "These
results suggest a new model for kinesin movement."
-----------
Y. Okada and N. Hirokawa: A processive single-headed motor:
Kinesin superfamily protein KIF1A.
(Science 19 Feb 99 283:1152)
QY: Nobutaka Hirokawa [hirokawa@m.u-tokyo.ac.jp]
-----------
Text Notes:
... ... *cilia: (plural of "cilium") In general, cilia are short
threadlike extensions, hundreds usually present on an individual
ciliated cell, the cilia undergoing synchronized movements to
produce locomotion of free-living cells or movement of the
extracellular medium in ciliated cells anchored in tissues. In
certain cells, a special type of cilium (stereocilium) is not 
motile but instead serves as a transducer responding to
extracellular stimuli.
... ... *flagella: (plural of "flagellum") A flagellum is a long
threadlike extension providing locomotion for a cell.
... ... *mitotic spindle: A structure composed of microtubules
that separates the two sets of chromosomes during cell division
in eukaryotes.
-------------------
Summary & Notes by SCIENCE-WEEK [http://scienceweek.com] 7May99
-------------------
Related Background:
MOTOR PROTEINS: DYNEIN ARMS AS FORCE GENERATORS
... Many eukaryotic cells (cells that have membrane-bound
organelles such as a cell nucleus) have flagella, long whip-like
structures, that beat rhythmically. The central core of the
flagellum is called the "axoneme", and it consists of a regular
array of microtubules (see background material in previous
report). The motor protein dynein is known to power flagellar
motion, suggesting that oscillation may be inherent in this
protein. ... ... Shingyoji et al (5 authors at 4 installations,
JP) report an attempt to determine whether oscillation is a
property of dynein arms themselves, or whether oscillation
requires an intact axoneme. Using *optical trapping nanometry,
the authors measured the force generated by a few dynein arms on
an isolated doublet microtubule. When the dynein arms on the
doublet microtubule contact a singlet microtubule and are
activated by photolysis of adenosine triphosphate (ATP), they
generate a force that moves the singlet microtubule over the
perpendicular doublet in a processive manner, the force and
displacement in oscillation, with the maximum frequency of the
oscillation dependent on ATP concentration. The authors suggest
that oscillation of dynein arms may be a basic mechanism
underlying flagellar beating, and that their results may be
important not only for understanding the mechanism of flagellar
beating, but also for understanding the functions of motor
proteins in general.
QY: Chikako Shingyoji (chikako@biol.s.u-tokyo.ac.jp)
(Nature 18 Jun 98 393:711) (Science-Week 10 Jul 98)
-------------------
Related Background:
... ... *optical trapping nanometry: The term "optical trapping"
refers to the confinement of (microscale) entities in a
restricted geometry by the controlled action of (laser) light,
and optical trapping nanometry is a method of making nanoscale
measurements of such entities. In this experiment, the optically
trapped entity is a fluorescent bead (1 micron diameter)
crosslinked with the biotin of the singlet microtubule, the
method allowing measurement of the nanoscale displacements of the
bead-microtubule entity as it is moved by the underlying doublet
dynein arms.
-------------------
Related Background:
MOTOR PROTEINS AND ORGANELLE TRANSPORT
The interior of a living cell is a dynamic system involving a
dynamic supporting matrix, active synthesis and degradation of a
variety of small and large molecules, and the regulated transport
of various molecular species to local and remote sites within the
cell. Research during the past two decades has provided
revelations concerning the molecular biology of a variety of
orchestrated movements with the cell interior, particularly
movements producing the transport of cell organelles (organized
subsystems). ... ... N. Hirokawa (University of Tokyo, JP)
reviews the molecular mechanisms of organelle transport in cells,
particularly the role of the motor proteins kinesin and dynein.
The author suggests that in the near future we will fully
understand how the cell sorts and transports proteins and lipids
to their appropriate intracellular destinations.
QY: Nobutaka Hirokawa [hirokawa@m.u-tokyo.ac.jp]
(Science 23 Jan 98) (Science-Week 6 Feb 98)
-------------------
Related Background:
INDUCED REVERSAL OF KINESIN MOTION IN CELLS
Microtubules are part of the cytoskeleton of biological cells,
the quasi-rigid matrix that among other things determines cell
shape. The microtubules are 25 nanometers in diameter, and
composed of the protein tubulin. They occur in regular arrays in
cilia, flagella, the mitotic spindle, and in the cytoplasm in
general, and they contribute not only to cell shape, but also to
cell motility. In the neuron axon, for example, the microtubules
are the rails along which material is transported in one
direction or another over long distances. Microtubules have
directionality, in the sense that the two ends apparently differ
chemically, and the difference can be recognized by certain cell
constituents. According to their organization in the cell, the
ends of the microtubules are labelled as plus or minus. Kinesin
is one of a family of motor proteins associated with micro-
tubules, the kinesin molecules able to move organelles and
particles toward one end of microtubules using energy derived
from adenosine triphosphate (ATP) hydrolysis. There are several
types of kinesin, and each type moves material in one direction
only, either toward the plus end of the microtubule or toward the
minus end of the microtubule. As far as its structure is con-
cerned, the protein kinesin apparently consists of two light
chains and two heavy chains combined to form a long thin molecule
with two globular heads at one end, with each of the globular
heads containing an ATP binding site. After the kinesin attaches
to an organelle that is to be transported, the head groups of the
kinesin molecule, by some means, "walk" along the surface of a
microtubule using energy from ATP hydrolysis. The head groups are
called the "motor domain", since they are evidently involved in
the movement process. Last week Ulrike Henningsen and Manfred
Schliwa (University of Munich, DE) reported what is being called
a remarkable experiment concerning kinesin. Essentially, what
they did is take two types of kinesin, one type that walks to the
plus end of microtubules, and another type that walks to the
minus end of the same microtubules, and using genetic engineering
methods, they produced a chimera, a new kinesin molecule with the
head of the minus walker and the tail of the plus walker, and
they demonstrated that the direction of movement of the kinesin
heads (the motor domains) were reversed by the tail substitut-
ions. This is a surprising result, and it has evidently caused
some excitement among biologists.
QY: M. Schliwa 
(Nature 4 Sep 97) (Science-Week 19 Sep 97)
-------------------
Related Background:
DETAILS OF DYNEIN MOTOR DOMAIN MECHANISMS
... Gee et al (3 authors at 3 installations, US) report that the
entire carboxy-terminal two-thirds of the 532K dalton force-
producing heavy chain subunit of dynein is required for ATP-
binding activity. They have also identified a distal microtubule-
binding domain that apparently forms a hairpin-like stalk. The
authors suggest the mechanism for dynein force production differs
substantially from that of other motor proteins.
QY: Richard B. Vallee [vallee@sci.wfbr.edu]
(Nature 11 Dec 97) (Science-Week 2 Jan 98)


5. 3-DIMENSIONAL STRUCTURE OF A GAP JUNCTION MEMBRANE CHANNEL
In addition to extracellular signaling pathways, some biological
cells in tissues use an alternative communications system that
involves direct movement of molecules from one cell to another.
This type of communication is made possible by what are called
"gap junctions", which permit small molecules to move directly
from cell to cell without passage through the extracellular
space. In thin-section electron micrographs, gap junctions appear
as regions in which the plasma membranes of two adjacent cells
are aligned in parallel and separated by a small gap of
approximately 3 nanometers. The membrane surfaces in this region
are covered by hundreds of resolved cylindrical structures called
"connexons", and each connexon is apparently constructed from a
single type of *transmembrane protein called "connexin". Gap
junctions occur in almost every type of cell found in
invertebrates and vertebrates, and they are especially abundant
in tissues where extremely rapid communication between cells is
required for optimal function. In heart tissue, for example, gap
junctions facilitate the flow of electric current that causes the
heart to beat. Several human diseases have been related to
connexin mutations, including developmental anomalies of the
cardiovascular system. Analysis of gap junction structure has
been limited to relatively low resolution studies, partly due to
the heterogeneity of tissue specimens. One approach is to use
*recombinant techniques to generate a homogenous population of
gap junctions for structural analysis. ... ... V.M. Unger et al
(4 authors at Scripps Research Institute, US) now report the
structure of a recombinant cardiac gap junction channel as
determined by electron crystallography at resolution of 7.5
angstroms in the membrane plane and 21 angstroms in the vertical
direction. The authors report the dodecameric channel is formed
by end-to-end docking of 2 hexamers, each of which displays 24
rods of density in the membrane interior, which is consistent
with an alpha-helical conformation for the 4 transmembrane
domains of each connexin subunit. The protein density forming the
extracellular vestibule apparently provides a tight seal to
exclude the exchange of substances with the extracellular milieu.
The authors suggest that connexon docking involves multivalent
interactions between connexons, and that this confers stability
in the formation of the intercellular channel.
-----------
V.M. Unger et al: Three-dimensional structure of a recombinant
gap junction membrane channel.
(Science 19 Feb 99 283:1176)
QY: Mark Yeager [yeager@scripps.edu]
-----------
Text Notes:
... ... *transmembrane protein: A transmembrane or membrane-
spanning protein essentially has 3 domains: extracellular,
membrane, and cytoplasmic (intracellular). In other words, the
protein extends completely through the plasma membrane,
protruding from the outer surface and inner surface of the
membrane. The outer portion of the protein may be a receptor for
one or more ligands, the protein acting to transduce a signal to
the interior of the cell. A "polytopic" protein is a
transmembrane protein that completely traverses the membrane two
or more times. (The protein connexin, mentioned in this report,
is a polytopic protein).
... ... *recombinant techniques: (genetic engineering techniques)
Genetic engineering is the general term used for recombinant DNA
technology, a set of methods for introducing foreign DNA into a
host organism. It usually but not always involves gene cloning.
In the context of this report, the essential idea is to introduce
DNA coding for a particular protein into a host organism genome
and subsequently use the organism as a "factory" to produce the
protein. In this report, cultured hamster kidney cells were
induced to express connexins.
-------------------
Summary & Notes by SCIENCE-WEEK [http://scienceweek.com] 7May99


6. PARKINSON'S DISEASE IN TWINS: AN ETIOLOGICAL STUDY
Parkinson's disease (also called Parkinson disease) is a slowly
progressive degenerative central nervous system disorder,
characterized by decreased movement, muscular rigidity, resting
tremor, and postural instability. The disease was first described
by James Parkinson (1817) and is now known to be associated with
degeneration of one or more specific regions of the brain
(dopaminergic neuron groups such as the *substantia nigra) and
resultant loss of *neural projections to several important brain
centers. Dopaminergic neurons are nerve cells that use dopamine
as a *neurotransmitter substance. Dopamine is found in several
major areas of the brain, and it is the degeneration of so-called
dopamine neurons that is apparently involved in Parkinson's
disease. One must distinguish "parkinsonism" from Parkinson's
disease. Parkinsonism is a syndrome (a complex of symptoms; in
this context, a complex of various movement symptoms) that may be
caused by Parkinson's disease, but which may also be caused by
infectious, vascular, pharmacological, toxic, metabolic,
structural, and various degenerative disorders. In other words,
not every individual with parkinsonism has Parkinson's disease.
The major differentiating characteristic is the response to the
drug "*levodopa", which is converted by the body into dopamine.
Individuals with parkinsonism who respond to levodopa treatment
receive a diagnosis of Parkinson's disease. At the present time,
Parkinson's disease is the 4th most common neurodegenerative
disease of the elderly. It affects approximately 1 percent of
people older than 65 years, and 0.4 percent of people between 40
and 65 years. The importance of inheritance in the origin of
Parkinson's disease has been debated for more than a century. In
the early 1980s, interest in an environmental cause of
Parkinson's disease was increased by evidence that the
neurotoxicant 1-methyl,4-phenyl,1,2,3,6-tetrahydropyridine (MTPT)
induces most of the signs and symptoms of Parkinson's disease in
humans and experimental animals. Recently, the genetic hypothesis
regained momentum with the identification of mutations in the so-
called "alpha-synuclein" gene or linkage to a region on
chromosome 2 in families with Parkinson's disease. Yet in most
cases of Parkinson's disease, family members are not affected,
and the alpha-synuclein mutation appears to be rare. Thus,
whether genetic factors are important in typical Parkinson's
disease is not clear. ... ... C.M. Tanner et al (7 authors at 3
installations, US) now report the largest twin study of
Parkinson's disease to date. The study involved 19,842 white male
twins enrolled in the National Academy of Sciences/National
Research Council World War II Veteran Twins Registry. Individuals
were screened for Parkinson's disease, and standard diagnostic
criteria were applied. The authors report that analysis of the
data indicates that genetic factors do not play a major role in
causing typical Parkinson's disease. No genetic component is
evident when the disease begins after age 50 years. In contrast,
genetic factors do appear to be important when the disease begins
at or before age 50 years. The authors suggest that in addition
to the implications for future research into the etiology of
Parkinson's disease, their results are of "obvious significance
to the families of persons with Parkinson's disease, most of
which need not assume that they have inherited the gene for
Parkinson's disease."
-----------
C.M. Tanner et al: Parkinson disease in twins.
(J. Amer. Med. Assoc. 27 Jan 99 281:341)
QY: Caroline M. Tanner [ctanner@parkinsoninstitute.org]
-----------
Text Notes:
... ... *substantia nigra: A large cell mass at the base of the
brain that receives input from a number of cortical and
subcortical structures ("cortical" refers to cerebral cortex).
... ... *neural projections: In general, the term "neural
projections" refers to the projected neural output from one
region to other regions.
... ... *neurotransmitter substance: Neurotransmitters are
chemical substances released at the terminals of nerve axons in
response to the propagation of an impulse to the end of that
axon. The neurotransmitter substance diffuses into the synapse,
the junction between the presynaptic nerve ending and the
postsynaptic neuron, and at the membrane of the postsynaptic
neuron the transmitter substance interacts with a receptor.
Depending on the type of receptor, the result may be an
excitatory or an inhibitory effect on the postsynaptic nerve
cell.
... ... *levodopa: (L-dopa) The biologically active form
of "dopa", which is converted into dopamine. Dopamine = 3,4-
dihydroxyphenylethylamine. Dopa = 3,4-dihydroxypheynylalanine.
-------------------
Summary & Notes by SCIENCE-WEEK [http://scienceweek.com] 7May99
-------------------
Related Background:
ON PARKINSON'S DISEASE
Parkinson's disease, first described by James Parkinson more than
180 years ago, is a major neurodegenerative disease of unknown
cause. ... ... A.E. Lang and A.M. Lozano present the first of a
2-part extensive review of the disease and make the following
points: 1) The disease effects over 1 million people in North
America. Age is the single most consistent risk factor, and the
prevalence of the disease is expected to rise steadily in the
future with the increasing age of the general population.
Mortality is 2 to 5 times as high among affected persons as among
age-matched controls, resulting in a marked reduction in life
expectancy. In general, neurodegenerative diseases (Parkinson's
disease, motor neuron disease, and dementia) are projected to
surpass cancer by the year 2040 as the second most common cause
of death among the elderly. 2) Parkinson's disease occurs
throughout the world, in all ethnic groups, and affects both
sexes approximately equally or with a slight predominance among
males. The prevalence increases exponentially with age between 65
and 90 years. Approximately 0.3 percent of the general population
and 3 percent of people over the age of 65 have the disease. 5 to
10 percent of patients have symptoms before the age of 40. The
lowest reported incidence is among Asians and African blacks,
whereas the highest reported incidence is among whites. 3) The
classic triad of major signs of Parkinson's disease consists of
tremor, rigidity, and akinesia (absence or loss of the power of
voluntary movement). The diagnosis is made on the basis of
clinical criteria, and underdiagnosis is common. Misdiagnosis is
also common, because the syndrome may be produced by different
causes such as drugs, *Wilson's disease, and other
neurodegenerative diseases. Although the neuropathological
examination is the standard for diagnosis of Parkinson's disease,
there is still no biological marker that unequivocally confirms
the diagnosis. 4) At the cellular level, Parkinson's disease is
characterized by the progressive death of specific but
heterogeneous populations of neurons, including *dopaminergic
neurons in the *substantia nigra, *aminergic *brainstem nuclei,
the *cholinergic *nucleus basalis of Meynert, *hypothalamic
neurons, and small *cortical neurons. In addition, degeneration
of nerve cells in the *olfactory bulb, *sympathetic ganglia, and
*parasympathetic neurons in the gut may also be involved in the
disease. 5) The mechanisms responsible for cell death in
Parkinson's disease are largely unknown. Evidence suggests that
neuronal death in the substantia nigra may involve *apoptosis,
but this idea is not universally accepted. Among the factors that
have been implicated in neuronal degeneration in this disease are
*mitochondrial dysfunction, *oxidative stress, the actions of
*excitotoxins, deficient *neurotrophic support, and immune
mechanisms. A critical question is why specific neurons are
selectively vulnerable to the disease.
-----------
A.E. Lang and A.M. Lozano (2 installations, CA)
Parkinson's disease.
(New England J. Med. 8 Oct 98 339:1044)
QY: Anthony E. Lang, Toronto Hospital, 399 Bathurst St., MP 11,
Toronto, ON M5T 2S8 CA.
-----------
Text Notes:
... ... *Wilson's disease:  A rare genetic disease involving
copper metabolism dysfunction.
... ... *dopaminergic neurons: Nerve cells that use dopamine as a
*neurotransmitter substance. "Levodopa", which is used in the
treatment of Parkinson's disease, is the biologically active form
of "dopa", which is converted into dopamine. Dopamine = 3,4-
dihydroxyphenylethylamine. Dopa = 3,4-dihydroxypheynylalanine.
... ... *neurotransmitter substance: Neurotransmitters are
chemical substances released at the terminals of nerve axons in
response to the propagation of an impulse to the end of that
axon. The neurotransmitter substance diffuses into the synapse,
the junction between the presynaptic nerve ending and the
postsynaptic neuron, and at the membrane of the postsynaptic
neuron the transmitter substance interacts with a receptor.
Depending on the type of receptor, the result may be an
excitatory or an inhibitory effect on the postsynaptic nerve
cell.
... ... *substantia nigra: A large cell mass at the base of the
brain that receives input from a number of cortical and
subcortical structures ("cortical" refers to cerebral cortex).
... ... *aminergic: In this context, the term refers in general
to neurons whose neurotransmitters are amines.
... ... *brainstem nuclei: Clusters of nerve cells in the
brainstem, which is a phylogenetically old region of the central
nervous system that among other things contains control centers
for fundamental physiological processes such as breathing and
heart rate. Anatomically, the brainstem is the connecting region
between the brain above it and spinal cord below it.
... ... *cholinergic: Refers to synaptic transmission mediated by
the release of acetylcholine.
... ... *nucleus basalis of Meynert: One of the basal nuclei
(neuron clusters) lying deep in the subcortical white matter of
the frontal lobes and involved in the organization of motor
behavior.
... ... *hypothalamic neurons: A deep brain structure with
various clusters of nerve cells controlling several important
homeostatic functions such as temperature regulation and food
intake, and in addition the sex drive, aggressive emotions,
psychosomatic effects, etc. The hypothalamus essentially
integrates the activity of the autonomic nervous system, and it
acts as an intermediary between the endocrine (hormone) system
and the nervous system, with various hypothalamic neuron types
secreting hormones themselves. In general, the term "hormones"
refers to chemical messengers which are distributed systemically
via the bloodstream. 
... ... *cortical neurons: In general, neurons of the cerebral
cortex, the phylogenetically newer part of the brain that
controls the higher analysis of sensory data and most non-
automatic activities.
... ... *olfactory bulb: Olfactory relay station that receives
axons from the olfactory cranial nerve and transmits the
information via the olfactory tract to higher centers.
... ... *sympathetic ganglia: Nerve cell clusters in the
sympathetic nervous system, which is a division of the peripheral
autonomic nervous system in vertebrates comprising, for the most
part, adrenergic neurons (nerve cells that secrete norepinephrine
or epinephrine as neurotransmitters) located relatively distant
from target organs.
... ... *parasympathetic neurons: The parasympathetic nervous
system is a division of the autonomic nervous system comprising
cholinergic nerve cells clusters located near target organs.
... ... *apoptosis: Programmed cell death produced by control
mechanisms designed to destroy defective cells.
... ... *mitochondrial dysfunction: Mitochondria are organelles
of the cell cytoplasm, and they are the principal energy source
of the cell, containing various enzymes involved in electron
transport and metabolic cycles.
... ... *oxidative stress: In this context, the term "oxidative"
refers to oxidative metabolism, a set of biochemical pathways
dependent on the utilization of supplied oxygen.
... ... *excitotoxins: Toxins that bind to certain neuron
receptors and which may be involved in neuron cell death. Certain
amino acids (e.g., glutamic acid) can act as excitotoxins, and
their study has given rise to the "excitotoxicity hypothesis",
which proposes that the effects produced by these amino acids are
caused by a prolonged depolarization of receptive neurons, the
process leading somehow to the eventual damage or death of these
nerve cells.
... ... *neurotrophic support: In general, neurons in the central
nervous system apparently depend for their survival on a number
of secreted substances called neurotrophins (neurotrophic
factors).
-------------------
Summary & Notes by SCIENCE-WEEK [http://scienceweek.com] 6Nov98
-------------------
Related Background:
IDENTIFICATION OF A GENE FOR JUVENILE PARKINSONISM
Parkinson's disease is a common neurodegenerative disease with
complex clinical features. Autosomal recessive juvenile
parkinsonism has been related to the long arm of chromosome 6 and
to several genetic markers. Kitada et al (9 authors at 4 install-
ations, JP) now report the identification of the gene related to
autosomal recessive juvenile parkinsonism. The entire gene spans
more than 500 kilobases. Mutations in this newly identified gene
appear to be responsible for the pathogenesis of the disease, and
the authors have named the protein product "parkin". The authors
suggest the protein parkin is apparently similar to the ubiquitin
family of proteins, which are involved in the pathogenesis of
several neurodegenerative diseases and are an evident component
of certain molecular entities in Alzheimer's disease. Further
investigation is necessary to establish the exact physiological
function of Parkin and how the  gene defects induce
selective degeneration of specific neurons.
QY: Nobuyoshi Shimizu 
(Nature 9 Apr 98 392:605) (Science-Week 1 May 98)
-------------------
Related Background:
DISCOVERY OF GENE IMPLICATED IN PARKINSON'S DISEASE
Defects in the structure of the protein alpha-synuclein have been
implicated in several human brain pathologies, including
Alzheimer's disease and Creutzfeld-Jacob disease. Now a specific
type of familial, early-onset Parkinson's disease has been added
to the list. Mihael H. Polymeropoulos (20 authors at various
installations, US, IT, GR) have identified a mutation in the
alpha-synuclein gene in three unrelated families of Greek origin
exhibiting inherited early-onset Parkinsonism. A consensus is
growing that defects in the structure of alpha-synuclein may be
responsible for an array of human brain pathologies, with at
least some of the protein structural defects caused by inherited
genetic mutations. Alpha-synuclein has been previously shown to
be a presynaptic nerve terminal protein. The early visible
symptoms of Parkinsonism are produced by destruction of nerve
cells producing the hormone dopamine. In later stages of the
disease, destruction of other types of nerve cells occurs. This
new study does not provide evidence for a genetic basis for all
cases of Parkinsonism, but it serves as a pointer for researchers
studying the molecular biology of the disease.
(Science 27 Jun 97) (Science-Week 3 Jul 97)


=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
 
IN FOCUS: ON MAX PLANCK
"Many kinds of men devote themselves to science, and not all for
the sake of science herself. There are some who come into her
temple because it offers them the opportunity to display their
particular talents. To this class of men science is a kind of
sport in the practice of which they exult, just as an athlete
exults in the exercise of his muscular prowess. There is another
class of men who come into the temple to make an offering of
their brain pulp in the hope of securing a profitable return.
These men are scientists only by the chance of some circumstance
which offered itself when making a choice of career. If the
attending circumstances had been different, they might have
become politicians or captains of business. Should an angel of
God descend and drive from the temple of science all those who
belong to the categories I have mentioned, I fear the temple
would be nearly emptied. But a few worshippers would still remain
-- some from former times and some from ours. To these latter
belongs our Planck. And that is why we love him."

-- Albert Einstein: (from the Preface to _Where is Science
   Going?_ by Max Planck)
   (Orginal German text 1933, English text Ox Bow Press 1981)

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

NOTICES 
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=

SCIENCE-WEEK SUBSCRIPTION RENEWAL OR EXTENSION INFORMATION:
-----------------------------------------------------------

Until August 1, 1999 the subscription rate for ScienceWeek is
US$10 per year. After that the rate will be US$20 per year.
Until August 1st, renewals or extensions at the current rate will
be accepted for any number of years.

CREDIT CARD PAYMENT:

Credit card payment can be made using a secure credit card form
that can be accessed at http://scienceweek.com/subinfo.htm

As an alternative, the following information can be supplied by
Email or regular mail or voice telephone or Fax:

Your name:
Duration of renewal or extension (1 or more yrs at US$10 per yr)
Your Email address:
Type of credit card (Visa, MasterCard, or American Express):
Credit card number:
Credit card expiration date:
Zip or postal code (if any) of your home address:

Please note: The credit card charge will be by Spectrum Press,
the publisher of SCIENCE-WEEK.

For transmission of credit card information:
Email: prismx@scienceweek.com
Fax: 773-281-1419 (24 hrs.- 7 days)
Voice phone: 888-281-1419 (toll-free US) (9am-5pm M-F CST)
             773-281-1419 (outside US) (9am-5pm M-F CST)

If you use PGP Email encryption software, our public key is at
http://scienceweek.com/pgp.txt

----------------------------------------------------------------
CHECK OR MONEY ORDER:

To subscribe by check or money order (drawn in US funds on a US
bank), please provide your name, Email address, subscription 
duration, along with a check or money order for US$10.00 per year
payable to "Spectrum Press", and send it to:

SCIENCE-WEEK/Spectrum Press
3023 N. Clark Street #109
Chicago, IL 60657
USA

----------------------------------------------------------------
When we receive payment, we will confirm receipt with an Email
message to your specified Email address.

=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
CHANGE OF EMAIL ADDRESS: If at any time you need to change the
Email address at which you receive SW, please send the
information to [request@scienceweek.com], and the change will be
made and confirmed the same day. 
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= 

The first issue of SCIENCE-WEEK appeared May 1, 1997, and it has
been published regularly each week since that date. We welcome
comments, suggestions, and criticisms from our subscribers.
Public letters relevant to any report are also welcome.
Editorial contact: [editors@scienceweek.com].

Editor/Publisher: Dan Agin
Managing Editor: Claire Haller
Associate Editor: Joan Oliner

Copyright (c) 1997-1999 SCIENCE-WEEK/Spectrum Press Inc.
All Rights Reserved

---------------------------------------------
This publication is protected by U.S. and International Copyright
Laws, and no display, transmission, or duplication in any medium,
including BBS, Internet Email, website duplication, fax, or print
is permitted without the explicit consent of the holder of the
copyright. SCIENCE-WEEK is published by Spectrum Press Inc.,
3023 N. Clark St. #109, Chicago, 60657 IL, US.
---------------------------------------------