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Decoded gene sequence of the diatom Thalassiosira pseudonana
October 01, 2004
For the very first time, the genetic make-up of a planktonic marine alga has been sequenced. During this process, a team of international scientists found unexpected metabolic pathways in the diatom Thalassiosira pseudonana. The results will be published in the scientific journal 'Science' this week. The fact that Thalassiosira pseudonana operates a urea cycle, has been a special discovery. Up to now, this metabolic pathway for ammonia detoxification was known only from the liver cells of animals and humans. It remains unclear how the cycle works in the alga. In addition, the diatom has two separate means for digesting fat, which is also unusual. One digestive mechanism is carried out as in animals, within mitochondria, the cell's 'power stations'. In contrast, fatty acids are broken down in regular plant-like fashion inside peroxysomes used for detoxification. Hence, the boundary between animals and plants appears blurred in this species of diatom.
The genome sequencing of Thalassiosira pseudonana is also of great interest for evolutionary biologists. Scientists came across genes which originate from the nucleus of a red alga. Gene transfer of this kind supports the theory of secondary endosymbiosis. Eukaryotes, such as diatoms, are complex cells with membrane bound nucleus and cell organelles. All living organisms other than bacteria are comprised of eukaryotic cells. Almost all eukaryotic cells, including human ones, have mitochondria. Plant and algal cells also contain plastids for photosynthesis. Originally, both types of organelles were bacteria that were incorporated by eukaryotic cells. For this reason, they are often termed 'primary endosymbionts'. In several cases, secondary endosymbiosis took place in that one eukaryotic cell was incorporated by another and subsequently reduced to a - now secondary - organelle. Diatoms appear to have engulfed a unicellular species of red alga and transformed it into a secondary plastid. "The diatom is some kind of a chimera of several organisms", says Dr Klaus Valentin of the Alfred Wegener Institute for Polar and Marine Research. This explains the presence of red algal genes in T. pseudonana according to Klaus Valentin, who participated in this project, among other ways, through identification of genes.
Diatoms such as Thalassiosira are of great ecological importance, because they contribute an estimated 20 percent to global primary production. Their role within the global carbon cycle is therefore comparable to tropical rain forests. The unicellular algae occur across the whole globe in ocean and fresh water environments, and even inhabit layers of liquid on soils, rocks or trees. They form the basis of a highly efficient food web, and, for this reason, are also key to commercial fisheries. For instance, the red pigments from diatoms are responsible for the red colouration of salmon. Diatoms carry their name for the presence of a two-part internal casing which consists of silica and may be beautifully ornamented.
The genome sequencing project of Thalassiosira pseudonana was coordinated by the USA and financed by the US Department of Energy. German participation in the project includes, apart from Dr Klaus Valentin of the Alfred Wegener Institute, Dr Nils Kröger, who holds a professorship of biochemistry at the University of Regensburg.
The article 'The Genome of the Diatom Thalassiosira pseudonana: Ecology, Evolution and Metabolism' will be published in the journal 'Science' on October 1.
Alfred Wegener Institut fuer Polar und Meeresforschung
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Genome: The Autobiography of a Species in 23 Chapters (P.S.)
by Matt Ridley (Author)
The genome's been mapped. But what does it mean? Arguably the most significant scientific discovery of the new century, the mapping of the twenty-three pairs of chromosomes that make up the human genome raises almost as many questions as it answers. Questions that will profoundly impact the way we think about disease, about longevity, and about free will. Questions that will affect the rest of your life. Genome offers extraordinary insight into the ramifications of this incredible breakthrough. By picking one newly discovered gene from each pair of chromosomes and telling its story, Matt Ridley recounts the history of our species and its ancestors from the dawn of life to the brink of future medicine. From Huntington's disease to cancer, from the applications...
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Genome
by Matt Ridley (Author)
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Genomes and What to Make of Them
by Barry Barnes (Author), John Dupre (Author)
The announcement in 2003 that the Human Genome Project had completed its map of the entire human genome was heralded as a stunning scientific breakthrough: our first full picture of the basic building blocks of human life. Since then, boasts about the benefits—and warnings of the dangers—of genomics have remained front-page news, with everyone agreeing that genomics has the potential to radically alter life as we know it. For the nonscientist, the claims and counterclaims are dizzying—what does it really mean to understand the genome? Barry Barnes and John Dupré offer an answer to that question and much more in Genomes and What to Make of Them, a clear and lively account of the genomic revolution and its promise. The book opens with a brief history of the science of genetics and...
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Genomes 3
by Terry Brown (Author)
Covering molecular genetics from the basics through to genome expression and molecular phylogenetics, Genomes 3 is the latest edition of this pioneering textbook. Newly updated to incorporate the recent major advances, Genomes 3 is an invaluable companion for any undergraduate throughout their studies in molecular genetics.
Genomes 3 builds on the achievements of the previous editions putting genomes, rather than genes, at the center of molecular genetics teaching. Recognizing that molecular biology research was being driven more by genome sequencing and functional analysis than by research into genes, this approach has gathered momentum in recent years.
The new edition has been significantly restructured and updated to incorporate recent major advances.
Key...
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A Short Guide to the Human Genome
by Stewart Scherer (Author)
How many genes are in the human genome? Which genes are commonly associated with genetic diseases? How many mobile elements, simple sequence repeats, or protein kinases are encoded in the genome? What are the largest genes and proteins? How similar are human proteins to those of mouse, yeast, or bacteria?
Although the human genome has been sequenced, it often can be surprisingly difficult to find answers to seemingly simple questions about its characteristics. This convenient handbook, written in question-and-answer format, allows researchers and teachers alike access to basic facts about the human genome.
Using a recent assembly of the human genome sequence, Stewart Scherer has compiled answers to a broad range of questions about the structure and function of the human...
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A Primer of Genome Science, Third Edition
by Gibson (Author), Muse (Author)
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The Genome War: How Craig Venter Tried to Capture the Code of Life and Save the World
by James Shreeve (Author)
The long-awaited story of the science, the business, the politics, the intrigue behind the scenes of the most ferocious competition in the history of modern science—the race to map the human genome. On May 10, 1998, biologist Craig Venter, director of the Institute for Genomic Research, announced that he was forming a private company that within three years would unravel the complete genetic code of human life—seven years before the projected finish of the U.S. government’s Human Genome Project. Venter hoped that by decoding the genome ahead of schedule, he would speed up the pace of biomedical research and save the lives of thousands of people. He also hoped to become very famous and very rich. Calling his company Celera (from the Latin for “speed”), he assembled a small...
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Welcome to the Genome: A User's Guide to the Genetic Past, Present, and Future
by Rob DeSalle (Author), Michael Yudell (Author), American Museum of Natural History (Author)
A thrilling "user's guide" to the genomics era Welcome to the genome, the miraculous blueprint of your DNA, coiled tight as a spring in the nucleus of each cell of your body. If unwound, the DNA from just one cell, while only a molecule in width, would stretch six feet in length! The information stored in its double helix structure - three billion bits worth - could fill 142 Manhattan phone books. Yet far more amazing than these facts is the impact the study of genomics has had on so many areas of our lives. From the promise of personalized medicine and gene therapy to disputes over the safety of genetically modified (GM) foods, there is little doubt we are in the midst of the Genomic Revolution. Now how do we make sense of it all? Welcome to the Genome takes...
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A Primer of Genome Science, 2nd Edition
by Greg Gibson (Author), Spencer V. Muse (Author)
A Primer of Genome Science bridges the gap between standard genetics textbooks and highly specialized, technical, and advanced treatments of the subdisciplines. It provides an affordable and up-to-date introduction to the field that is suited to advanced undergraduate or early graduate courses. Bioinformatic principles and experimental strategies are explained side-by-side with the experimental methods, establishing a framework that allows teachers to explore topics and the literature at their own pace.
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A Life Decoded: My Genome: My Life
by J. Craig Venter (Author)
The triumphant true story of the man who achieved one of the greatest feats of our era—the mapping of the human genome
Growing up in California, Craig Venter didn’t appear to have much of a future. An unremarkable student, he nearly flunked out of high school. After being drafted into the army, he enlisted in the navy and went to Vietnam, where the life and death struggles he encountered as a medic piqued his interest in science and medicine. After pursuing his advanced degrees, Venter quickly established himself as a brilliant and outspoken scientist. In 1984 he joined the National Institutes of Health, where he introduced novel techniques for rapid gene discovery, and left in 1991 to form his own nonprofit genomics research center, where he sequenced the first genome in...
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