MARSBUGS:  
The Electronic Astrobiology Newsletter
Volume 5, Number 21, 18 September 1998.

Editors:

Dr. David Thomas, Department of Biological Sciences, University of 
Idaho, Moscow, ID, 83844-3051, USA.  Marsbugs@aol.com or 
davidt@uidaho.edu.

Dr. Julian Hiscox, Division of Molecular Biology, IAH Compton 
Laboratory, Berkshire, RG20 7NN, UK.  Julian.Hiscox@bbsrc.ac.uk

Marsbugs is published on a weekly to quarterly basis as warranted 
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The purpose of this newsletter is to provide a channel of 
information for scientists, educators and other persons interested 
in exobiology and related fields.  This newsletter is not intended 
to replace peer-reviewed journals, but to supplement them.  We, 
the editors, envision Marsbugs as a medium in which people can 
informally present ideas for investigation, questions about 
exobiology, and announcements of upcoming events.

Astrobiology is still a relatively young field, and new ideas may 
come out of the most unexpected places.  Subjects may include, but 
are not limited to:  exobiology and astrobiology (life on other 
planets), the search for extraterrestrial intelligence (SETI), 
ecopoeisis and terraformation, Earth from space, planetary 
biology, primordial evolution, space physiology, biological life 
support systems, and human habitation of space and other planets.
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CONTENTS

1)	JODRELL BANK SEARCHES FOR EXTRATERRESTRIAL CIVILIZATIONS
University of Manchester press release PR9802

2)	LAB RECEIVES NASA FUNDING TO TEST CRITICAL INSTRUMENT 
COMPONENTS FOR POSSIBLE USE ON FUTURE EUROPA MISSION
Los Alamos National Laboratory release

3)	FOSSILIZED MAGNETOTACTIC BACTERIUM IN THE ORGUEIL METEORITE
By Brig Klyce

4)	GREAT BUGS OF FIRE:  PROTEIN FROM VOLCANO-LOVING BUG 
CRYSTALLIZED IN SPACE
By David Noever

5)	NATURE'S "ELECTRONIC INK":  RETINAL PROTEIN CRYSTALLIZED ON 
SPACE MISSION
By David Noever 

6)	NATURE'S SUGAR HIGH:  SPACELAB SUCCESSFULLY CRYSTALLIZES 
INTENSELY SWEET PROTEIN
By David Noever 
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JODRELL BANK SEARCHES FOR EXTRATERRESTRIAL CIVILIZATIONS
University of Manchester press release PR9802

12 September 1998

The University of Manchester's Lovell radio telescope at Jodrell 
Bank has begun to take part in the most sensitive and 
comprehensive search ever undertaken for radio communications 
signals from Extra-Terrestrial Civilizations beyond our Solar 
System.  The collaborative research program with the SETI 
Institute, called Project Phoenix, is using the 76-m Lovell 
telescope and the 305-m Arecibo telescope, located in Puerto Rico.  
The radio telescopes have begun to make observations of the 
regions around several hundred Sun-like stars that lie within a 
distance of 200 light years.

Ian Morison, who is coordinating the Jodrell Bank observations, 
explained that, "Astronomers expect that other civilizations are 
most likely to be found on planets in orbit around stars similar 
to our Sun.  Such stars live long enough and provide enough heat 
to allow life a chance to evolve."

Jodrell Bank is a world leader in the development of advanced 
radio receivers which when used with the Lovell telescope, the 
second largest fully-steerable radio telescope in the world, make 
it exceptionally sensitive to faint radio signals.  Jill Tarter, 
Director of the SETI Institute, points out that "by using the 
Arecibo and Lovell telescopes in the search we will have the most 
sensitive system possible."

The privately-funded SETI Institute, in California, has continued 
the development of a NASA multi-million-channel receiver, which is 
capable of efficiently searching a wide band of frequencies where 
extra-terrestrial signals might be found.  The receiver is located 
at the Arecibo telescope and will be used to make the initial 
detection of signals having the appropriate characteristics.  The 
Lovell telescope will then be immediately used to eliminate earth-
based interference or confirm any suspected extra-terrestrial 
signal.  Previous searches for Life in the Universe have always 
been plagued with the problem of discriminating between a "true" 
extra-terrestrial signal and those originating on Earth or from 
artificial satellites.  As Ian Morison explains:  "local signals 
are eliminated by making simultaneous observations with the two 
radio telescopes.  Due to their transatlantic separation, a signal 
has to come from a very great distance, from at least the outer 
part of our solar system, for the computer-based detection systems 
to be triggered at both telescopes.  Fortunately, we can make a 
regular check on the system by receiving the signal from the 
Pioneer 10 spacecraft, now far beyond the orbit of Pluto."

The search is being undertaken during two three-week observing 
sessions each year and will continue for several years.  As 
Professor Andrew Lyne, Director of Jodrell Bank, said "If an 
extra-terrestrial signal were detected, it would be one of the 
most dramatic discoveries ever made.  We are glad that we can make 
a contribution to this exciting scientific quest."

The support material at http://www.jb.man.ac.uk/research/seti 
gives background to:
1.	The history of SETI and The SETI Institute.
2.	Project Phoenix--of which these observations are a part.
3.	SETI Questions--Answers to often asked questions given by 
Jill Tarter and Ian Morison.
4.	The Drake Equation--a look at the probability of contacting 
other civilizations.
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LAB RECEIVES NASA FUNDING TO TEST CRITICAL INSTRUMENT COMPONENTS 
FOR POSSIBLE USE ON FUTURE EUROPA MISSION
Los Alamos National Laboratory release

16 September 1998

Los Alamos National Laboratory scientists recently received a 
$120,000 grant from NASA to use Laboratory space instrument design 
and manufacturing expertise and test critical components of an 
instrument that may lead to a final product for use on a future 
mission to the Jupiter moon Europa.  Concurrently, three Los 
Alamos researchers are part of a 17-member international team 
working on a feasibility study for NASA to determine the technical 
requirements for an instrument to study the moon's icy surface.  
The preliminary report is due November 1.

Called the Ice Penetrating Radar, the instrument would use a 
three-antenna array that sends millions of radar signals at 
different frequencies to map out the thickness of Europa's ice 
surface and detect, if present, a subsurface Europan ocean.  The 
IPR also would characterize Europa's ice surface.  A liquid ocean 
is the most important ingredient in the development and sustenance 
of life; detecting and characterizing Europa's oceans, if present, 
are an integral part of scientists' search for evidence of life in 
the solar system.

"If we can confirm the existence of a water ocean on Europa, it 
would be the only ocean known to exist in our solar system outside 
of Earth's," said Brad Edwards of Los Alamos' Space and Remote 
Sensing Sciences Group.  Edwards also is part of the 17-member 
Instrument Definition Team, which includes researchers from around 
the world.

Because ice is transparent to a large range of radar signals, the 
IPR will be able to record waves reflected off the top layer of 
ice and the ice-water interface, ultimately converting them into 
three-dimensional images.

"We think the ice crust surface could be as deep as 100 
kilometers, but data we received from the Galileo spacecraft 
indicate that the ice could be as thin as hundreds of meters," 
explained Edwards.  Photos transmitted by the Galileo spacecraft 
in 1994 presented the first evidence of the possible existence of 
liquid water on Europa.

"If a water ocean does exist on Europa, the IPR can map thin areas 
of the ice surface for future lander missions to Europa to sample 
the water for signs of life," said Edwards.

Edwards said the Instrument Definition Team currently is studying 
many things, including how to distinguish the different radar 
reflection signals returned by rocks, cracks in the ice, salty and 
non-salty ice, and other conditions on the moon's surface.  
Another obstacle is making sure the IPR survives Jupiter's intense 
radiation that surrounds Europa, he added.

"The radiation around Europa measures about 25 megarads per month.  
That's enough radiation to fry a desktop computer in about five 
minutes," he said.

Still another important consideration is determining just how much 
power the IPR will need in order to transmit and receive its radar 
signals and the kinds of antennas that need to be used, said Xuan-
Min Shao of Los Alamos' Space and Atmospheric Sciences Group and 
fellow IDT member.  Shao said he hopes to begin testing the IPR 
prototype's antennas within the next couple of months.  The 
testing will take place at Los Alamos.

Shao said the instrument's weight is another major factor in 
designing and building the prototype.  "We think the Ice 
Penetrating Radar should weigh no more than eight kilograms," he 
said, or about 17 pounds.

The final draft design for the IPR is scheduled to be submitted to 
NASA sometime in March 1999, said Edwards.  At that time, NASA 
will put out an announcement for opportunities for the Europa 
mission, scheduled for launch sometime in 2004.  It would take 
anywhere from five to seven years for the instruments to reach 
Europa, after which time measurements would be taken for about a 
month.

The IPR is one of a suite of instruments--called a strawman's 
payload--that NASA currently is considering sending to Europa, the 
other instruments being an optical camera, transponder and laser 
altimeter.  The IPR is the primary instrument; the laser altimeter 
would be used to measure the tidal bulge of Europa's surface 
caused by Jupiter's tremendous gravitational pull on the moon.  
"The laser altimeter will measure the moon's tides.  If they're 
small, then we'll know that there's little or no water underneath 
the surface," said Edwards.

Shao said although it is conceivable that NASA may choose an 
instrument suite that does not include the IPR for the Europa 
mission, because the IPR is one of only a few instruments that can 
both measure Europa's ice surface depth and characterize its 
structure, there is a good chance that it will remain part of the 
suite that ultimately makes the 400-million-mile trek.

The University of California operates Los Alamos National 
Laboratory for the U.S. Department of Energy.
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FOSSILIZED MAGNETOTACTIC BACTERIUM IN THE ORGUEIL METEORITE
By Brig Klyce
From Common Ancestry

8 September 1998

In 1966, W. C. Tan and Sam L. VanLandingham examined samples of 
the Orgueil meteorite.  Like the Murchison meteorite, Orgeuil is a 
carbonaceous chondrite.  It was seen as it fell near Orgueil, 
France, on May 14, 1864.  Samples of it have been extensively 
studied, especially by Bart Nagy, whose photos of lifelike fossils 
in it were published in Nature, in the early 1960s.  The above 
photo was among several dozen by Tan and VanLandingham of fossils 
in Orgueil that looked biological to them.  It was among a handful 
published in a very brief article in the Journal of the Royal 
Astronomical Society, in 1967 (1).

In those days, Tan and VanLandingham had no idea what the 
"filamentary microstructures" like this one might be, because they 
had never heard of magnetotactic bacteria.  Today however, we do 
know about such bacteria.  They ingest and retain iron, which 
causes them to align themselves with a magnetic field.  If enough 
of them die and become fossilized together, the matrix will be a 
"natural magnet".  Sam VanLandingham says that the Orgueil sample 
in which the fossil was found had many similar fossils, all neatly 
aligned, pointing the same way.

When seen through a transmission electron microscope, the most 
striking feature of magnetotactic bacteria is the magnetosomes 
inside them.  These membrane-bound particles of magnetite (iron 
oxide) appear as dark, regularly spaced inclusions whose geometry 
and spacing vary from one species to another.  (In this example 
they resemble dark portholes on a tiny submarine.)

The picture below shows a typical magnetotactic bacterium, of the 
species Rhodopseudomonas rutilis.  Its size and shape are very 
similar to those of the fossil above.  Most telling, however, is 
the match in size, shape and spacing of the magnetosomes.  In 
1998, NASA's Richard Hoover first showed the above photo to 
Russian bacteriologist Mikhail Vainshtein, who studies 
magnetotactic bacteria.  He recognized it immediately.  The photo 
below came from Vainshtein's collection (2).

The fossil from the Orgueil meteorite, photographed in 1966, was 
first identified as a magnetotactic bacterium like the one in the 
lower photo only this year.  We suggest that this evidence of a 
fossilized bacterium in a carbonaceous chondrite cannot be easily 
dismissed.

References

1.  Tan, W. C. and S. L. VanLandingham.  "Electron microscopy of 
biological-like structures in the Orgueil carbonaceous meteorite," 
p 237 v 12 Geophys. J. Royal Astr. Soc., 1967.
2.  Hoover, Richard; Alexei Yu. Rozanov; S. I. Zhmur and V. M. 
Gorlenko.  "Further Evidence of Microfossils in Carbonaceous 
Chondrites," in Instruments, Methods, and Missions for 
Astrobiology, Richard B. Hoover, Editor, Proceedings of SPIE Vol. 
3441, p 203-216 (1998).  (May be ordered through Proceedings of 
SPIE.)

[Additional information on this article may be found at 
http://www.panspermia.org/magneto.htm]
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GREAT BUGS OF FIRE:  PROTEIN FROM VOLCANO-LOVING BUG CRYSTALLIZED 
IN SPACE
By David Noever 
From NASA Space Science News

16 September 1998

They may be small, but they're very hot.  They're the archaea, an 
ancient branch of microbial life on Earth discovered by scientists 
in 1977.  Unlike the better known bacteria and eukaryotes (plants 
and animals), many of the archaea can thrive in extreme 
environments like volcanic vents and acidic hot springs.  They can 
live without sunlight or organic carbon as food, and instead 
survive on sulfur, hydrogen, and other materials that normal 
organisms can't metabolize.  It may sound like science fiction, 
but many scientists are working rapidly to explore the biology as 
well as the practical benefits of these recently discovered life 
forms.

An enzyme, alcohol dehydrogenase (ADH), is derived from a member 
of the archaea called Sulfolobus solfataricus.  It works under 
some of nature's harshest volcanic conditions.  It can survive to 
88 C (190F)--nearly boiling--and corrosive acid conditions 
(pH=3.5) approaching the sulfuric acid found in a car battery 
(pH=2).  ADH produces ethanol naturally and has considerable 
potential for biotechnology applications due to its stability 
under these extreme conditions.  To understand how it works, 
scientists first need to learn its basic structure.  For this, an 
Italian research team went to space.

After collecting Sulfolobus solfataricus from the Solfatara 
volcanic area near Naples, the Italian team purified the ADH 
enzyme for crystallization aboard the Space Shuttle.  Compared to 
crystals grown in Earth's gravity, the space crystals showed an 
improved quality of nearly 35%, and the researchers obtained 
diffraction data with a significantly higher resolution, 
indicating reduced disorder.  Scientists hope to use the space 
grown crystals to improve the biological understanding of how 
these molecules work based on a detailed knowledge of their shape 
and exact atomic positions.

A fundamental question posed by the space shuttle investigation 
is:  what features of these volcanic microbes' metabolism allow 
for such thermal stability in their enzymes? If unusual 
characteristics in their metabolism can be identified and studied, 
the transfer of this knowledge is almost immediate to applications 
in environmental cleanup, pollution prevention, or energy 
production.  Many researchers envision a range of medically, 
industrially, and environmentally useful compounds derived from 
the extreme heat-loving, or "hyperthermophilic" Archaea.  
Biomolecules from these organisms are active at temperatures that 
generally degrade normal cellular molecules, such as enzymes, 
lipids, and nucleic acids.

When stored at room temperature, these molecules from volcanic 
microbes are in the "deep freeze" compared to their normal lives, 
thus offering tremendously extended shelf-life and stability in 
commercial use.

The first Archaea-related products were DNA polymerases for the 
research market.  For example, New England Biolabs, a Beverly, MA-
based biotechnology company, sells Vent and Deep Vent polymerases, 
used in DNA sequencing.  These enzymes originally were isolated 
from hyperthermophiles associated with oceanic hydrothermal vents.  
Without analysis of these fiery microbes, neither the modern 
identification of human genetic diseases nor the use of DNA 
evidence in legal courts would even have been realized.

The Archaea

Researchers say that the heat and geochemical conditions in 
volcanic regions may be similar to conditions that existed on the 
young, water-covered, cooling Earth.  Almost like a creature from 
science fiction, the volcanic microbe is different from the two 
other basic branches of life:  bacteria and eukaryotes.  The 
prokaryotes are the bacteria, while eukaryotes are the so-called 
higher forms of life, including humans, plants and animals.

A major difference is that eukaryotes put their genes inside a 
nucleus, while prokaryotes do not.  In the archaea, there is no 
nucleus, but many genes behave like those in higher organisms.  
Archaea are thought to have a common ancestor with bacteria, but 
billions of years ago the third domain, eukaryotes, broke off from 
archaea, eventually developing into plants, animals and us.  
Archaea include microbes that live at the extremes of the planet - 
the very, very cold, hot or high-pressure places that no other 
form of life could endure.

As such, archaea are the extremophiles who boldly thrive where no 
other life form would go.  Some scientists have suggested that as 
such, archaea may represent the earliest form of life and thus may 
be the most likely form of life existing on other planets.  About 
500 species of archaea are now identified, but speculation may not 
be far off in projecting that given the difficulties of collecting 
and classifying them, there may be a million others.  The life 
form is thought to produce about 30 percent of the biomass on 
Earth, much of it in the Antarctic Ocean.  In fact, as far back as 
1994, Myrna Watanabe, a biotechnology consultant, wrote that the 
existence of this third branch of life "here on Earth has led 
scientists to realize that planets they hitherto assumed to be 
lifeless might support life."

Much work remains to be done in uncovering the shape and detailed 
way that these extreme microbial molecules achieve their thermal 
stability.  In a controlled study comparing space grown crystals 
with the best data ever previously obtained from ADH crystals 
formed on Earth, the Italian team found that the "the 
microgravity-grown crystals displayed increased stability when 
exposed to X-rays." This finding moves the investigation closer to 
revealing the biological function of these complex molecules.  
According to their report, although future flights will be 
required to solve the fully three-dimensional picture of the 
molecule, the Space Shuttle provided larger, more ordered and more 
radiation-stable examples of this microbial enzyme.

[More information concerning this article may be found at 
http://science.msfc.nasa.gov/newhome/headlines/msad16sep98_1.htm]
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NATURE'S "ELECTRONIC INK":  RETINAL PROTEIN CRYSTALLIZED ON SPACE 
MISSION
By David Noever 
From NASA Space Science News

17 September 1998

Anyone who has ever fallen on grass knows that nature has 
chemicals that are as permanent as ink.  At least one of those 
chemicals holds promise as an "electronic ink" that can be used in 
improved computer displays.  The chemical is bacteriorhodopsin, a 
purple protein essential to the cell wall of Halobacterium 
halobium, a mysterious resident of salt marshes and lakes.  When 
nutrients get scarce, this bacteriorhodopsin becomes a light-
converting enzyme that keeps the organism's life cycle going.  
It's a protein powerhouse that in times of famine flips back and 
forth between purple and yellow colors.  If controllable, this 
could be valuable in computer display panels.

In the last 25 years, bacteriorhodopsin has excited a great deal 
of interest among biochemists, biophysicists, and most recently 
among companies seeking to build battery-conserving, long-life 
computer displays.  The protein, sometimes called nature's 
"electronic ink" was grown in orbit on board the Space Shuttle for 
a scientific team from Justus-Liebig University in Glessen, 
Germany and the Institute for Physiological Chemistry in Hamburg.

Part of the attraction to understanding these light powerhouses is 
that natural materials often perform very complex functions that 
cannot be easily obtained from manufactured materials such as 
semiconductors.  They have been optimized for these functions by 
billions of years of evolution and often perform them better than 
any human-designed material could.  

For example, bacteriorhodopsin is an attractive material for all-
optical "light" computers because of its two stable protein forms, 
one purple and one yellow.  Shining two lasers of different 
wavelengths alternately on the protein flips it back and forth 
between the two colors.  Several research groups have already used 
bacteriorhodopsin as computer memory and as the light-sensitive 
element in artificial retinas.

According to their report, the space crystal was stabilized under 
microgravity conditions...  Further experiments in microgravity, 
as a favorable environment of improved crystallogenesis, provide 
additional progress in the investigation of difficult membrane 
proteins such as bacteriorhodopsin.

In nature, this salt-loving, probably ancient, organism undergoes 
a light-stimulated cycle of protein rearrangements, which can 
interact photochemically.  This may be how similar retinal 
proteins in the eye allow more evolved organisms to see.  
Analyzing them on Earth has been difficult because these kinds of 
complex membrane proteins typically require detergents to make 
them compatible with biological analysis in water.

The cubic-shaped space crystals showed a nearly 20-fold larger 
volume compared to earth-grown counterparts.  In comparing space 
grown crystals of the bacteriorhodopsin with similar crystals 
formed on earth, the team found that a favorable environment 
minimizing gravity might advance the search for new means to 
reveal the biological function of these complex molecules.  The 
large volume of the space-grown crystals will help scientists read 
the protein's blueprint and understand how it operates.  From 
this, they hope to develop versions that could be used in future 
computers.

[More information concerning this article may be found at 
http://science.msfc.nasa.gov/newhome/headlines/msad17sep98_1.htm]
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NATURE'S SUGAR HIGH:  SPACELAB SUCCESSFULLY CRYSTALLIZES INTENSELY 
SWEET PROTEIN
By David Noever 
From NASA Space Science News

14 September 1998

Your sweet tooth may get a treat that is literally "out of this
world," thanks to experiments aboard the Space Shuttle.  A team 
comprising French and American scientists reports they have 
crystallized one of the most interesting families of intensely 
sweet proteins, a natural molecule called thaumatin, isolated from 
the African Serendipity Berry (Thaumatococcus daniellii).

Using otherwise similar crystallizing conditions, the space 
crystal showed a nearly 25% larger volume compared to its earth-
grown counterparts and yielded nearly twice the crystalline order.  
Scientists hope to use the space-grown crystals to improve the 
biological understanding of how these molecules work based on 
detailed knowledge of their shape and exact atomic positions.  
According to the study, the visual quality of the space crystals 
"appeared virtually flawless, with no observable imperfections, 
striations or anomalies."

The complex and costly management of human diabetes, obesity, and 
oral health has spawned a widespread search for natural sugar 
substitutes that are both non-caloric and safe.  The calorie-free 
thaumatin protein, sometimes called nature's "artificial 
sweetener" was analyzed by scientists from the University of 
California, Irvine and the Institute for Molecular Biology in 
Strasbourg, France.

In a control study, the team compared space-grown thaumatin 
crystals with some previously obtained from on earth in a 
conventional laboratory.  They found that the space crystals 
provided 30% more real information about the molecule's shape.  
This moves the investigation closer to revealing the biological 
function of these complex molecules.

According to their report, the space crystals reinforce the 
conclusion of other reports based on different macromolecules that 
a microgravity environment provides distinct advantages.  In the 
best of only a few thaumatin crystals grown in microgravity, 
compared with many more trials conducted on earth, the 
microgravity grown crystals were consistently and significantly 
larger, and substantially more defect free.  This is the first 
experiment to produce space crystals by multiple methods, both 
suggesting the same conclusion:  crystals grown in microgravity 
can be significantly improved in their x-ray diffraction 
properties when compared with those grown on earth.

The natural proteins as a group are the sweetest compounds ever 
discovered.  The sweet taste--which depends on nearly 100 
different sensory receptors on the tongue--can be detected in the 
presence of thaumatin at concentrations well below one part 
protein molecule per 100 million parts of water.  On a scale in 
which 0 refers to no sweetness, 1 refers to table sugar or 
sucrose, then thaumatin is nearly off the scale at 3,000, more 
than 10 times sweeter than other sugar substitutes like saccharin 
or aspartame.

Because these kinds of complex sensory-stimulating proteins 
typically require binding to specific taste receptors, much of 
their biology remains to be worked out in the kind of studies done 
on the space shuttle and using modern tools of biological 
crystallography.  Already within the bulk commercialization by 
biotechnology companies, Tate & Lyle's product, Talin, is marketed 
from thaumatin.  Also, at the Unilever Research Laboratory in The 
Netherlands, the gene for this sweetener has been cloned into 
biological production using the microorganisms E. coli and yeast 
to substitute for the original African shrub.

As a non-caloric sweetener, thaumatin has attracted attention as a 
candidate for control of obesity, oral health and diabetic 
management.  Thaumatin already is being marketed as a nutritional 
supplement in blood sugar stabilizers for childhood behavioral 
problems and the more than 3.5 million sufferers from attention 
deficit disorder.  Among soft drink consumers alone, nearly 20.6 
million tons of chemicals are used around the world--nearly 4 
kilograms per capita, with a growth of about 20% towards the end 
of the decade.

Control of diabetes, the most common metabolic disease in the 
world, largely hinges on managing sugar levels in the bloodstream.  
According to a recent study published in the Journal of Clinical 
Endocrinology and Metabolism, one out of every seven health care 
dollars, or $105 billion, goes to the treatment of diabetes-
related complications.  Individual diabetics spent an average of 
$9,493 on health care in 1992, the latest data available, compared 
with $2,604 for people without diabetes, the study said.  Nearly 
600,000 people per year are diagnosed as diabetic in the US.  The 
National Institutes of Health proved that diabetic patients who 
can maintain blood-sugar levels as close as possible to normal can 
significantly slow the disease.

Biotechnology in space

Some estimates suggest that human biology depends on the action of 
nearly half a million different enzymes and proteins.  In less 
than 1 case in 100, we have a three-dimensional picture of shape 
and function of these complex chemicals.  Since 1984, the Space 
Shuttle has carried experiments to determine the structures of 
large, biologically important molecules.  This research has 
compiled results for a host of human diseases ranging from insulin 
(for the control of diabetes) to one enzyme called reverse 
transcriptase that can be blocked to inhibit HIV infection.

In comparing more than 33 such different biological molecules 
crystallized on the Shuttle and also in similar conditions on 
earth, space produced larger space crystals in 45% of the cases 
and new structures in nearly 20% of the cases.  As many as half 
the space crystals had a 10% or better improvement in the x-ray 
brightness or the crystallographic resolution.  Both are important 
to determining these large molecules' shape and exact atomic 
positions.

[More information on this article may be obtained at 
http://science.msfc.nasa.gov/newhome/headlines/msad14sep98_1.htm]
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End Marsbugs Vol. 5, No. 21




