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Marsbugs: The Electronic Astrobiology Newsletter, Volume 11, Number 17, 20 April 2004
Marsbugs: The Electronic Astrobiology Newsletter
Volume 11, Number 17, 20 April 2004
Editor/Publisher: David J. Thomas, Ph.D., Science Division, Lyon College, Batesville, Arkansas 72503-2317, USA.
Marsbugs is published on a weekly to monthly basis as warranted by the number of articles and announcements. Copyright of this compilation exists with the editor, except for specific articles, in which instance copyright exists with the author/authors. Opinions expressed in this newsletter are those of the authors, and are not necessarily endorsed by the editor or by Lyon College. E-mail subscriptions are free, and may be obtained by contacting the editor. Information concerning the scope of this newsletter, subscription formats and availability of back-issues is available at http://www.lyon.edu/projects/marsbugs. The editor does not condone "spamming" of subscribers. Readers would appreciate it if others would not send unsolicited e-mail using the Marsbugs mailing lists. Persons who have information that may be of interest to subscribers of Marsbugs should send that information to the editor.
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Marsbugs: The Electronic Astrobiology Newsletter, Volume 11, Number 17, 20 April 2004
Articles and News
Page 1 BIOLOGIST'S FIND ALTERS THE BACTERIA FAMILY TREE
By Falland Toscano
Page 2 HUMANS AND CLIMATE DESTROY REEF ECOSYSTEM
By Rebecca Lindsey
Page 5 THE GREATEST CATASTROPHE ON EARTH: INTERVIEW WITH PETER WARD, AUTHOR OF GORGON
By Leslie Mullen
Page 6 UA'S LUNINE TO TESTIFY BEFORE PRESIDENTIAL COMMISSION FRIDAY (APRIL 16)
By Lori Stiles
Page 6 U-M STUDENT RESEARCH MAY HELP ASTRONAUTS BURN FUEL ON MARS
University of Michigan release
Page 7 A "DRAGON" ON THE SURFACE OF TITAN
European Southern Observatory release
Page 9 SCIENTISTS HOPE BUSH SPACE PLAN RESTORES MARS GREENHOUSE FUNDS
By Chris Kridler
Page 9 SUPERWASP BEGINS THE SEARCH FOR THOUSANDS OF NEW PLANETS
Particle Physics and Astronomy Research Council release
Page 10 THE BRICKS OF LIFE: EXPLORING THE IDEA OF ALIEN CHEMISTRY
By Seth Shostak
Page 10 COSMIC MAGNIFYING GLASS: DISTANT STAR REVEALS PLANET
NASA release 04-127
Page 11 KECK TELESCOPE IMAGES YIELD MOVIE OF TITAN'S HYDROCARBON HAZE
By Robert Sanders
Page 12 BIOLOGY HANGING BY A THREAD? THE KNOLL CRITERION ON MARS
From Astrobiology Magazine
Page 12 DO MER PHOTOS SHOW EXTANT MARTIAN ORGANISMS (PART 1 OF 2)?
By Francisco J. Oyarzun
Page 15 SETI INSTITUTE SCIENTIST NAMED TO TIME MAGAZINE TOP 100 FOR THE 20TH CENTURY
SETI Institute release
Announcements
Page 15 NEW ADDITIONS TO THE ASTROBIOLOGY INDEX
By David J. Thomas
Mission Reports
Page 16 CASSINI SIGNIFICANT EVENTS
NASA/JPL release
Page 17 MARS ROVER FINDS ROCK RESEMBLING METEORITES THAT FELL TO EARTH
NASA/JPL release 2004-104
Page 18 MARS GLOBAL SURVEYOR IMAGES
NASA/JPL/MSSS release
Page 18 MARS ODYSSEY THEMIS IMAGES
NASA/JPL/ASU release
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Marsbugs: The Electronic Astrobiology Newsletter, Volume 11, Number 17, 20 April 2004
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Marsbugs: The Electronic Astrobiology Newsletter, Volume 11, Number 17, 20 April 2004
BIOLOGIST'S FIND ALTERS THE BACTERIA FAMILY TREE
By Falland Toscano
Washington Universtiy in St. Louis release
7 April 2004
The bacteria family tree may be facing some changes due to the recent work of an evolutionary biologist at Washington University in St. Louis. And that may change our understanding of when bacteria and oxygen first appeared on earth. Carrine Blank, Ph.D., assistant professor of earth and planetary sciences in Arts & Sciences, has found that the currently accepted dates for the appearance of oxygen-producing bacteria and sulfur-producing bacteria on the early earth are not correct. She believes that these bacteria appeared on Earth much later than is now believed. Blank's findings appear in the February 2004 issue of Geobiology.
"It sets up a new framework of new hypotheses to be tested," she says of the new findings.
As an evolutionary biologist, Blank said she is, "really interested in the view of the Earth and microorganisms and how they come together." She uses elements of biology and geology to understand how the earth and its inhabitants co-evolved.
It is known that Earth's earliest organisms were thermophilic, or able to dwell in hot environments. These organisms engaged in chemotropic metabolism—they converted inorganic substances, such as sulfur and carbon, into energy to live. This process is similar to how we use food, water, and oxygen to generate energy.
The predecessors of modern bacteria differ in much more than age. The Archean era, which records the first billion years of Earth's geologic history, ended 2.5 billion years ago. It was at this point that the earth's biosphere must have changed and the atmospheric temperature reached 72 degrees Celsius. This is the maximum temperature at which photosynthesis can take place. Near the end of this era, about 2.7 to 2.9 billion years ago, according to Blank, stromatolites, organisms of the group Bacteria that use photosynthesis to create energy without producing oxygen, first appeared.
Blank's approach is to understand organisms by determining what materials they metabolized. Using genetic analysis, she looked at the early rock record to determine when the first substantial amounts of oxygen and sulfur appeared on Earth. While she mapped the evolution of several bacteria, Blank believes the dating of the emergence of cyanobacteria—bacteria that use light, water, and carbon dioxide to produce oxygen and biomass—is most crucial.
Blank explains that the precise dating of the emergence of cyanobacteria is so important because, "once you have oxygen, you have a whole new biosphere."
Left: cyanobacteria became the first microbes to produce oxygen by photosynthesis. Image credit: UC Berkeley. Right: microbial mat producing oxygen through photosynthesis. Image credit: UTA Department of Geology.
Cyanobacteria are the only bacteria that produce oxygen as a byproduct of their metabolism. It was not until these creatures appeared on earth that oxygen was found in the earth's atmosphere. "No other photosynthetic microbe is as efficient," said Blank.
Scientists initially believed that cyanobacteria were present on earth as early as 2.7 billion years ago. Blank has challenged this view by presenting dates she feels give a more accurate chronology of the evolution of cyanobacteria and other bacteria lineages in general. With this data, she was also able to better pinpoint the emergence of other organisms. She has determined that cyanobacteria can only be dated to as far back as 2.3 billion years ago.
Genetic analysis
Blank used an evolutionary analysis technique pioneered by Carl Woese, Ph.D., professor emeritus of microbiology at the University of Illinois, to construct evolutionary trees of the bacteria. Woese pioneered the technique of using ribosomal RNA genes to make the first family trees of microbes. He was also the first person to distinguish between the two domains of microbial life—Bacteria and Archaea. These Archaea are not related to the Archean era mentioned previously.
Using many genes that are common to all these creatures, Blank was able to construct evolutionary trees with better chronological accuracy than those produced previously, which used fewer genes. Based on the extent of the changes, Blank could determine how distant the organism was from the last common ancestor.
Blank obtained her gene sequences from whole genome sequences that are available in GenBank, a public database hosted by the National Institutes of Health. This provided large amounts of data to enhance the evolutionary trees. From these data, Blank's diagrams show how different types of metabolism evolved. For example, her data show that oxygen-producing organisms evolved from organisms that metabolize sulfur. Her diagrams are based on the idea that evolution is a branching process in which a common ancestor's descendants slowly diverged into a few organisms, each of which diverged into a few more, and so on until the multitude of the organisms we see today developed.
These family trees also show which organism's genes are least like the last common ancestor's genes. These organisms will be more toward the tips of the lines, while those with genes that closely resemble the genes of the last common ancestor will be closer to the center of the tree. "The tips of the tree use oxygen, so they first originated the use of oxygen," explained Blank.
Opening new areas of study
While Blank sites evidence in the geologic record as the reason her findings are more accurate than previous ones, she does acknowledge that there is one piece of evidence that may disprove her proposed chronology. Lipid markers, similar to fossils in the rocks in that they provide evidence of species' presence in the past, in the rock record indicate that cyanobacteria may have been present as early as 2.7 billion years ago. But, because ancient lipid research just started in 1999, this evidence is still being examined.
Blank's research also brings up the question of how nuclei functioned for a billion years before mitochondria appeared. Mitochondria are the powerhouse of the cell; they process resources and convert them into cellular energy. While mapping genomes for her research, Blank noticed that prior to 2.2 billion years ago, mitochondria were not present in eukaryotic cells—more highly developed cells that contain mitochondria and other organelles in a membrane. "This is an intriguing insight into eukaryote evolution," said Blank.
Read the original news release at http://news-info.wustl.edu/tips/page/normal/793.html.
An additional article on this subject is available at http://www.astrobio.net/news/article928.html.
HUMANS AND CLIMATE DESTROY REEF ECOSYSTEM
By Rebecca Lindsey
From NASA's Earth Observatory
13 April 2004
In late 1997, cool water from deep in the Indian Ocean was welling up to the surface along the coast of Indonesia. The cool water would have chilled the coral reefs near the Mentawai Islands off the west coast of Sumatra. If corals had a consciousness, however, they wouldn’t have been worried. Over the past 7,000 years, these cold spells had come and gone, and the reefs had barely acknowledged their presence.
Meanwhile, to the east, a strong El Niño was drying out Indonesia’s tropical forests, especially in Borneo and Sulawesi. With rainfall 400-500 millimeters below the annual average, trees would have been slowing down photosynthesis and shedding leaves to prevent water loss. No stranger to El Niño, however, the forest, if it had a consciousness, probably wouldn’t have been too alarmed. It had withstood such droughts before.
The Mentawai Islands, fringed by coral reefs, lie 160 km (100 miles) off the coast of Sumatra, on the eastern edge of the Indian Ocean. Map adapted by Robert Simmon.
What happened next, though, is a stunning and heartbreaking example of how human activity superimposed on Earth’s natural cycles of variation can disrupt the dynamic and delicate balance of life and climate. As 1997 became 1998, a sequence of climatic coincidences became a catastrophe when thousands of square kilometers of tropical forests damaged by human impacts went up in flames, indirectly killing almost the entire 400-kilometer Mentawai coral reef system off the coast of Sumatra.
Corals tell a 7,000-year story of the Indian Ocean
The cold water upwelling in the eastern Indian Ocean is part of a climate phenomenon called the Indian Ocean Dipole, during which the eastern half of the ocean becomes much cooler than the western half. Along with these changes in ocean temperature, strong winds blow from east to west at the equator, across Indonesia and the eastern Indian Ocean. The cool ocean temperatures begin to appear south of the island of Java in May and June along with moderate southeasterly winds. Over the next few months, both the winds and cool temperatures intensify and spread northeastward toward the equator. The southeastern Indian Ocean may become as many as 5 to 6 degrees Celsius cooler than the western part.
Water temperatures around the Mentawai Islands dropped about 4° Celsius during the height of the Indian Ocean Dipole in November of 1997. During these events unusually strong winds from the east push warm surface water towards Africa, allowing cold water to upwell along the Sumatran coast. In this image blue areas are colder than normal, while red areas are warmer than normal. Image based on data from the IRI/LDEO Climate Data Library.
The cooling of the ocean in the coastal zone around the Mentawai Islands during Indian Ocean Dipole events influences the circulation of the atmosphere and rainfall, and it’s related to major droughts in Indonesia and Australia and floods in eastern Africa. In 2001, geologist and marine scientist Nerilie Abram was studying the climate history of the Indian Ocean as part of her Ph.D. studies in the School of Earth Sciences at the Australian National University, when she and her colleagues made a surprising discovery: nearly 100 percent of the Mentawai corals were dead!
Nerilie Abram and her colleagues discovered the reef death in the Mentawai Islands while sampling corals in an effort to reconstruct past climate. Nearly all of the region’s coral had been dead since 1997, including this lifeless coral (left) being sampled by a diver (photograph by Stewart Fallon). The team drilled cores from fossil reefs along the shoreline (right), in addition to the recently dead underwater corals. The result was a record of coral growth and ocean temperatures that extended up to 7,000 years ago (photograph by Kriton Glenn).
"Our research group initially started working in the Mentawai Islands because this region is vital in controlling the climate of the Indian Ocean region," explains Abram. They were planning to use the coral reefs to put together a 7,000-year record of the region’s climate. "As corals grow, the chemistry of their skeletons preserves a detailed record of the environmental conditions." Because the kinds of chemicals that make it into the corals’ skeletons depend on ocean conditions like salinity and temperature, the chemical composition reflects the ancient climate. Equipped with scuba and snorkeling gear, Abram and her colleagues set out to sea for several months on an Indonesian dive boat. But when they arrived at the Mentawai reefs, she says, "We were surprised to find that the entire reef ecosystem had been killed. By talking to locals and other researchers working in the region we found that the coral and fish in the Mentawai reefs had all been killed when the ocean turned red in 1997, at around the peak of the 1997 Indian Ocean Dipole event."