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Research Reveals Major Insight Into Evolution Of Life On Earth
ScienceDaily (Aug. 20, 2009) — Humans might not be walking the face of the Earth were it not for the ancient fusing of two prokaryotes — tiny life forms that do not have a cellular nucleus. UCLA molecular biologist James A. Lake reports important new insights about prokaryotes and the evolution of life in the Aug. 20 advance online edition of the journal Nature.
See also:
Plants & Animals
* Cell Biology
* Microbiology
* Genetics
Fossils & Ruins
* Origin of Life
* Fossils
* Evolution
Reference
* Prokaryote
* Organelle
* Eukaryote
* Plant cell
Endosymbiosis refers to a cell living within another cell. If the cells live together long enough, they will exchange genes; they merge but often keep their own cell membranes and sometimes their own genomes.
Lake has discovered the first exclusively prokaryote endosymbiosis. All other known endosymbioses have involved a eukaryote — a cell that contains a nucleus. Eukaryotes are found in all multicellular forms of life, including humans, animals and plants.
"This relationship resulted in a totally different type of life on Earth," said Lake, a UCLA distinguished professor of molecular, cell and developmental biology and of human genetics. "We thought eukaryotes always needed to be present to do it, but we were wrong."
In the Nature paper, Lake reports that two groups of prokaryotes — actinobacteria and clostridia — came together and produced "double-membrane" prokaryotes.
"Higher life would not have happened without this event," Lake said. "These are very important organisms. At the time these two early prokaryotes were evolving, there was no oxygen in the Earth's atmosphere. Humans could not live. No oxygen-breathing organisms could live."
The oxygen on the Earth is the result of a subgroup of these double-membrane prokaryotes, Lake said. This subgroup, the cyanobacteria, used the sun's energy to produce oxygen through photosynthesis. They have been tremendously productive, pumping oxygen into the atmosphere; we could not breathe without them. In addition, the double-membrane prokaryotic fusion supplied the mitochondria that are present in every human cell, he said.
"This work is a major advance in our understanding of how a group of organisms came to be that learned to harness the sun and then effected the greatest environmental change the Earth has ever seen, in this case with beneficial results," said Carl Pilcher, director of the NASA Astrobiology Institute, headquartered at the NASA Ames Research Center in Moffett Field, Calif., which co-funded the study with the National Science Foundation.
"Along came these organisms — the double-membrane prokaryotes — that could use sunlight," Lake said. "They captured this vast energy resource. They were so successful that they have more genetic diversity in them than all other prokaryotes.
"We have a flow of genes from two different organisms, clostridia and actinobacteria, together," he said. "Because the group into which they are flowing has two membranes, we hypothesize that that was an endosymbiosis that resulted in a double membrane. It looks as if a single-membrane organism has engulfed another. The genomes are telling us that the double-membrane prokaryotes combine sets of genes from the two different organisms."
For this study, Lake has looked back more than 2.5 billion years. He conducted an analysis of the genomics of the five groups of prokaryotes.
Lake is interested in learning how every organism is related.
"We all are interested in our ancestors," he said. "A friend at UC Berkeley, Alan Wilson, was the first person to collect DNA from large numbers of people around the world. He showed that we are all related to a woman who lived in Africa 200,000 years ago. Some in the media called her Eve. He called her the Lucky Mother, the mother of us all.
"In our field, we have enormous amounts of data but cannot make sense of it all. Endosymbiosis allows us to start to understanding things; it tells us that many genes are exchanged.
"We have been overlooking how important cooperation is," Lake said. "If two prokaryotes get together, they can change the world. They restructured the atmosphere of the Earth. It's a message that evolution is giving us: Cooperation is a way to get ahead."
Actinobacteria have an unusual DNA composition, with a very high amount of "G" and "C" nucleotides — chemicals whose patterns carry the data required for constructing proteins. Nucleotides are designated by the letters G (guanine), C (cytosine), A (adenine) and T (thymine); the sequence of nucleotides serves as a chemical code.
Some actinobacteria are pathogens, including ones that cause tuberculosis and leprosy. Some clostridia can photosynthesize, which no other single-membrane prokaryote does. Photosynthesis may have been developed in clostridia.
Double-membrane prokaryotes include the pathogens that cause ulcers, as well as the organisms that led to the creation of the chloroplasts that are in all green plants and which make plant growth possible.
Adapted from materials provided by University of California - Los Angeles, via EurekAlert!, a service of AAAS.
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Scanning electron micrograph of a species of actinobacteria: Actinomyces israelii. (Credit: Courtesy of Wikipedia)
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Research Reveals Major Insight Into Evolution Of Life On Earth
ScienceDaily (Aug. 20, 2009) — Humans might not be walking the face of the Earth were it not for the ancient fusing of two prokaryotes — tiny life forms that do not have a cellular nucleus. UCLA molecular biologist James A. Lake reports important new insights about prokaryotes and the evolution of life in the Aug. 20 advance online edition of the journal Nature.
See also:
Plants & Animals
* Cell Biology
* Microbiology
* Genetics
Fossils & Ruins
* Origin of Life
* Fossils
* Evolution
Reference
* Prokaryote
* Organelle
* Eukaryote
* Plant cell
Endosymbiosis refers to a cell living within another cell. If the cells live together long enough, they will exchange genes; they merge but often keep their own cell membranes and sometimes their own genomes.
Lake has discovered the first exclusively prokaryote endosymbiosis. All other known endosymbioses have involved a eukaryote — a cell that contains a nucleus. Eukaryotes are found in all multicellular forms of life, including humans, animals and plants.
"This relationship resulted in a totally different type of life on Earth," said Lake, a UCLA distinguished professor of molecular, cell and developmental biology and of human genetics. "We thought eukaryotes always needed to be present to do it, but we were wrong."
In the Nature paper, Lake reports that two groups of prokaryotes — actinobacteria and clostridia — came together and produced "double-membrane" prokaryotes.
"Higher life would not have happened without this event," Lake said. "These are very important organisms. At the time these two early prokaryotes were evolving, there was no oxygen in the Earth's atmosphere. Humans could not live. No oxygen-breathing organisms could live."
The oxygen on the Earth is the result of a subgroup of these double-membrane prokaryotes, Lake said. This subgroup, the cyanobacteria, used the sun's energy to produce oxygen through photosynthesis. They have been tremendously productive, pumping oxygen into the atmosphere; we could not breathe without them. In addition, the double-membrane prokaryotic fusion supplied the mitochondria that are present in every human cell, he said.
"This work is a major advance in our understanding of how a group of organisms came to be that learned to harness the sun and then effected the greatest environmental change the Earth has ever seen, in this case with beneficial results," said Carl Pilcher, director of the NASA Astrobiology Institute, headquartered at the NASA Ames Research Center in Moffett Field, Calif., which co-funded the study with the National Science Foundation.
"Along came these organisms — the double-membrane prokaryotes — that could use sunlight," Lake said. "They captured this vast energy resource. They were so successful that they have more genetic diversity in them than all other prokaryotes.
"We have a flow of genes from two different organisms, clostridia and actinobacteria, together," he said. "Because the group into which they are flowing has two membranes, we hypothesize that that was an endosymbiosis that resulted in a double membrane. It looks as if a single-membrane organism has engulfed another. The genomes are telling us that the double-membrane prokaryotes combine sets of genes from the two different organisms."
For this study, Lake has looked back more than 2.5 billion years. He conducted an analysis of the genomics of the five groups of prokaryotes.
Lake is interested in learning how every organism is related.
"We all are interested in our ancestors," he said. "A friend at UC Berkeley, Alan Wilson, was the first person to collect DNA from large numbers of people around the world. He showed that we are all related to a woman who lived in Africa 200,000 years ago. Some in the media called her Eve. He called her the Lucky Mother, the mother of us all.
"In our field, we have enormous amounts of data but cannot make sense of it all. Endosymbiosis allows us to start to understanding things; it tells us that many genes are exchanged.
"We have been overlooking how important cooperation is," Lake said. "If two prokaryotes get together, they can change the world. They restructured the atmosphere of the Earth. It's a message that evolution is giving us: Cooperation is a way to get ahead."
Actinobacteria have an unusual DNA composition, with a very high amount of "G" and "C" nucleotides — chemicals whose patterns carry the data required for constructing proteins. Nucleotides are designated by the letters G (guanine), C (cytosine), A (adenine) and T (thymine); the sequence of nucleotides serves as a chemical code.
Some actinobacteria are pathogens, including ones that cause tuberculosis and leprosy. Some clostridia can photosynthesize, which no other single-membrane prokaryote does. Photosynthesis may have been developed in clostridia.
Double-membrane prokaryotes include the pathogens that cause ulcers, as well as the organisms that led to the creation of the chloroplasts that are in all green plants and which make plant growth possible.
Adapted from materials provided by University of California - Los Angeles, via EurekAlert!, a service of AAAS.
Email or share this story:
| More
Need to cite this story in your essay, paper, or report? Use one of the following formats:
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enlarge
Scanning electron micrograph of a species of actinobacteria: Actinomyces israelii. (Credit: Courtesy of Wikipedia)
Related Stories
Map Of Life On Earth Could Be Used On Mars (May 13, 2005) — A geologist from Washington University in St. Louis is developing new techniques to render a more coherent story of how primitive life arose and diverged on Earth -- with implications for Mars. ... > read more
What Are The Odds Of Finding Extraterrestrial Intelligent Life? (Apr. 19, 2008) — A mathematical model suggests that the odds of finding new life on other Earth-like planets are low, given the time it has taken for beings such as humans to evolve and the remaining life span of the ... > read more
Billions Of Years Ago, Microbes Were Key In Developing Modern Nitrogen Cycle (Mar. 3, 2009) — New research shows that the large-scale evolution of microbes was mostly complete 2.5 billion years ago, and that included the beginning of the modern aerobic nitrogen ... > read more
'Tree Of Life' Has Lost A Branch, According To Largest Genetic Comparison Of Higher Life Forms Ever (Jan. 22, 2008) — Biologists have made a startling discovery about the relationship between organisms that most people have never heard of. The Tree of Life must be re-drawn, textbooks need to be changed, and the ... > read more
Ancient Proteins Rebuilt To Reveal Primordial Earth's Temperature (Feb. 16, 2008) — Researchers reconstruct proteins from ancient bacteria to measure the Earth's temperature over the ages. The scientists determined that the Earth endured a massive cooling period between 500 million ... > read more
Biogenic Origin For Earth's Oldest Putative Microfossils (July 2, 2009) — Microbes and bacteria were the first living organisms on Earth, and they can be preserved in Archean silica-rich rocks. One such outcrop from western Australia, dated to 3.5 billion years ago, may ... > read more
Investigating The Invisible Life In Our Environment (Feb. 5, 2007) — A new computational method to analyse environmental DNA samples, developed by researchers at the European Molecular Biology Laboratory (EMBL) in Heidelberg, now sheds light on the microbial ... > read more
Mineral Kingdom Has Co-evolved With Life, Scientists Find (Nov. 14, 2008) — Evolution isn't just for living organisms. Scientists have found that the mineral kingdom co-evolved with life, and that up to two thirds of the more than 4,000 known types of minerals on Earth can ... > read more
Search ScienceDaily
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Enter a keyword or phrase to search ScienceDaily's archives for related news topics,
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Just In:
Lightning's Mirror Image ... Only Much Bigger
Using Light To Teach Magnets New Tricks
Microchip Does 1,000 Chemical Reactions At Once
Naming Evolution's Winners And Losers
Inner 'Fingerprint' For Personal Medical Care
Why Sleep? To Boost Efficiency, Minimize Risk
Ultrathin LEDs: New Class Of Displays
Oxycholesterol: Greatest Heart Disease Risk?
Science Video News
Discovering A New Earth 430 Light Years Away
Astrophysicists analyzing infrared images captured by the Spitzer Space Telescope found indications of a dust cloud surrounding a relatively young. ... > full story
* Paleontologists Teach Medical Students About Fossil Tumors
* Geoscientists Investigate Rare Carbon Formation
* Astrophysicists Search Skies For A Moon Like Earth's
* more science videos
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* S.Korea seeks 4-year prison term for stem cell fraud
* Encyclopedia of Life grows; clues on ageing, pests
* Satellites put into orbit for Japan and Australia
* Scientists make "sugar bug" drug for bowel disease
* Gene swap experiment makes altering bugs easier
* more science news
In Other News ...
* Netanyahu sees talks with Palestinians in 2 months
* Storm Bill loses steam in North Atlantic
* Fires near Athens recede after 3-day inferno
* Malaysian state to cane woman after Ramadan
* Justice Dept advises pursuing CIA abuses: report
* Facebook to boost staff by 50% in 2009: report
* U.S. presses sanctions to end N.Korea atomic plans
* Singapore shoots down "rumor" of APEC attack plot
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