Saturday, July 29, 2006


Giant Dinosaur Discovered in Argentina

Puertasaurus reuili Titanosaur Evolution Dinosaur Argentina Research

Argentina: Scientists have discovered gigantic neck, back, and tail bones from one of the largest dinosaurs ever to roam the Earth.

Most impressive is a back vertebra that measures 3.48 feet (1.06 meters) tall and 5.51 feet (1.68 meters) wide, according to Fernando Novas. The paleontologist announced the find at the Argentine Museum of Natural Sciences in Buenos Aires on July 21.

The new species is one of the titanosaurs, a group of plant-eating sauropod dinosaurs that walked on four feet and are known for their long necks and tails.

Based on analysis of the vertebrae and comparison with smaller, better-known titanosaurs, the paleontologist believes the new find was 115 to 131 feet (35 to 40 meters) long and weighed between 88 and 110 tons (80 and 100 metric tons).

[The titanosaur has been named Puertasaurus reuili]

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New genus of Collembola named after Grinnell College and alumna

Collembola Amber Fossil Myanmar Burma Evolution Research

Grinnell, Iowa - A Grinnell College biology professor has discovered a new genus of an extinct branch of the Collembola, a group of small arthropods partly responsible for the nutritious soil farmers enjoy.

The genus, located in amber discovered in Myanmar (Burma), is a relative of the more than 4,000 species of Collembola, also called springtails, found throughout the world today.

"The Collembola is a group often ignored and mostly misunderstood," said Ken Christiansen, professor emeritus of biology at Grinnell College, Grinnell, Iowa, and a leading researcher of Collembola worldwide. "I feel certain that if Collembola were the size of cats there would be whole zoos devoted to them because they are so weird and varied. They are among the most numerous arthropods on earth's surface, with as many as a trillion in an acre of soil."

..."I feel very honored to have a species named after me," said Ventis. "I think that the descriptions ... will shed new light on questions about mass extinctions and about the evolution of Collembola." [cretaceous]

Featured book: George Poinar's "Lebanese Amber: The Oldest Insect Ecosystem in Fossilized Resin" (Amazon UK | US)

Books on Amber Fossils from the Science and Evolution Bookshop: UK | US

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Friday, July 28, 2006


Unusual Mechanism Keeps Repair Protein Accurate

Cancer researchers have discovered that a recently identified protein critical for repairing damaged genes uses an unusual mechanism to keep its repairs accurate.

The protein, called DNA polymerase lambda, is one of a group of proteins known as DNA polymerases that are vital for accurately making and repairing DNA.

But while other DNA-repair proteins insure their accuracy with the help of so-called proof-reading regions or accessory molecules, this protein maintains its accuracy using an otherwise ordinary-looking portion of its molecular structure.

The study was led by Zucai Suo, assistant professor of biochemistry and a researcher with the Ohio State University Comprehensive Cancer Center - Arthur G. James Cancer Hospital and Richard J. Solove Research Institute. The research, published in the July 14 issue of The Journal of Biological Chemistry (Abstract), provides new insights into how cells repair damaged DNA.

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UCR researchers show how the brain turns on innate behavior

Riverside, California: UCR researchers have made a major leap forward in understanding how the brain programs innate behavior. The discovery could have future applications in engineering new behaviors in animals and intelligent robots.

Innate or 'instinctive' behaviors are inborn and do not require learning or prior experience to be performed. Examples include courtship and sexual behaviors, escape and defensive maneuvers, and aggression.

Using the common fruit fly as a model organism, the researchers found through laboratory experiments that the innate behavior is initiated by a 'command' hormone that orchestrates activities in discrete groups of peptide neurons in the brain. Peptide neurons are brain cells that release small proteins to communicate with other brain cells and the body.

The researchers report that the command hormone, called ecdysis-triggering hormone or ETH, activates discrete groups of brain peptide neurons in a stepwise manner, making the fruit fly perform a well-defined sequence of behaviors. The researchers propose that similar mechanisms could account for innate behaviors in other animals and even humans.

Study results appear as the cover article in this week's issue of Current Biology (Abstract).

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Pterosaur flying reptile mystery 'solved'

UK scientists say they have solved the mystery of why prehistoric flying reptiles grew crests on their heads.

A rare skull specimen found in Brazil shows the crest appeared at puberty, suggesting it was used to attract attention from the opposite sex.

University of Portsmouth experts say pterosaurs, which ruled the air during the time of the dinosaurs, flaunted their headgear in sexual displays.

The findings are published in the journal Palaeontology (Abstract).

Palaeobiologist Dr Darren Naish said the crest was a signal of sexual maturity; used like a peacock's tail to attract a mate.

"It would have been like a gigantic cockerel's comb, a brightly-coloured striking structure used in display," he told the BBC News website.

Books on Dinosaurs from the Science and Evolution Bookshop: UK | US

Books on Paleontology from the Science and Evolution Bookshop: UK | US

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Scientists Say They've Found a Code Beyond Genetics in DNA

[New York Times: May require free registration]

Researchers believe they have found a second code in DNA in addition to the genetic code.

The genetic code specifies all the proteins that a cell makes. The second code, superimposed on the first, sets the placement of the nucleosomes, miniature protein spools around which the DNA is looped. The spools both protect and control access to the DNA itself.

The discovery, if confirmed, could open new insights into the higher order control of the genes, like the critical but still mysterious process by which each type of human cell is allowed to activate the genes it needs but cannot access the genes used by other types of cell.

The new code is described in the current issue of Nature by Eran Segal of the Weizmann Institute in Israel and Jonathan Widom of Northwestern University in Illinois and their colleagues.

NB The Nature journal article the above refers to is "A genomic code for nucleosome positioning" (Abstract).

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Thursday, July 27, 2006


God, Under a Microscope

A Washington Post book review of The Language of God: A Scientist Presents Evidence for Belief by Francis S. Collins (Amazon UK | US).

Williamstown, Massachusetts:

He opened the session by improvising on hymns at the piano and concluded it by accompanying a singalong on the guitar. In between, he delivered a compelling account of his unlikely conversion from atheism to evangelical Christianity.

The lanky, amiable personality wasn't a traveling revivalist but one of the world's leading biologists.

Francis S. Collins (biography) led the international Human Genome Project that mapped the 3.1 billion chemical base pairs in humanity's DNA. He now directs the U.S. government program on applying that information to medical treatments.

He has also emerged as an advocate for faith and its compatibility with science.

The 56-year-old Collins discussed the clash of science and religion last weekend during a conference at Williams College sponsored by the C.S. Lewis Foundation. The writings of the English literature scholar were instrumental in Collins's conversion.

Continued at "Biologist Preaches That Religion and Science Can Coexist"

Listen to Francis Collins discuss his book on NPR's 'Talk of the Nation'. The other Guest is Owen Gingerich, author of God's Universe (UK | US). [Audio]

Read a 4 page excerpt from The Language of God: A Scientist Presents Evidence for Belief by Francis S. Collins (UK | US).

Books on 'Science and Religion' from the Science and Evolution Bookshop: UK | US

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Secrets of a Cellular Machine

Kenneth Downing and Haixin Sui of Berkeley Lab's Life Sciences Division have pioneered the use of cryo-electron tomography to examine the ubiquitous protein structures called axonemes, which form the cores of the cilia and flagella of eukaryotic cells.

Axonemes are some of nature's largest molecular machines. Their principal structural elements are microtubules, tough and versatile protein assemblies that perform many cellular roles, notably as major components of the cell skeleton. In 1998 Downing and Eva Nogales, then a scientist in his group, with colleague Sharon Wolf, first revealed the structure of alpha and beta tubulins, the protein dimers from which microtubules are constructed. In 2002 Downing and Huilin Li, also a scientist in his group, published details of a microtubule's structure at eight-angstrom resolution, better than twice that ever obtained before.

"In the present work Haixin Sui and I were initially looking to follow up the earlier work on tubulin," Downing says. "In mammals tubulin comes in many forms, so we intended to isolate the simple form in sea urchin eggs in hopes of making better crystals. It turned out that we also collected a lot of sea urchin sperm, which are an excellent source of axonemes.

[The above is based on "Molecular architecture of axonemal microtubule doublets revealed by cryo-electron tomography," by Haixin Sui and Kenneth H. Downing, which can currently be downloaded from here.]

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Greek paleontologists find rare prehistoric primate skull

Kriopigi, Greece: Paleontologists in northern Greece have unearthed the intact skull of a prehistoric primate that lived at least five million years ago, a member of the research team said on Wednesday.

"The skull still carries the bite marks of a large carnivore, it ranks among the best preserved ever found," Aristotelio University assistant professor of geology Evangelia Tsoukala told AFP.

"It gives us a complete image of the animal, as it preserves all its facial characteristics."

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Models show one nearby star system could host Earthlike planet

The steady discovery of giant planets orbiting stars other than our sun has heightened speculation that there could be Earth-type worlds in nearby planetary systems capable of sustaining life. Now researchers running computer simulations for four nearby systems that contain giant planets about the size of Jupiter have found one that could have formed an Earth-like planet with the right conditions to support life.

A second system is likely to have a belt of rocky bodies the size of Mars or smaller. The other two, the models show, do not have the proper conditions to form an Earth-size planet. Each system lies within 250 light years of Earth (a light year is about 5.88 trillion miles). Astronomers already have found evidence that each system contains at least two giant planets about the mass of Jupiter, which have migrated close to their stars, perhaps as close as Mercury is to the sun.

For each of the four systems, the researchers conducted 10 computerized simulations that placed small planet embryos, or protoplanets, in the system to see if they are able to gather more material and form a true planet the size of Earth. Each simulation assumed the same conditions in the planetary system except that the position and mass of each protoplanet was altered slightly, said Sean Raymond, a postdoctoral researcher at the University of Colorado, who took part in the work while he was an astronomy doctoral student at the University of Washington.

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Baked scorpions solve fossil puzzle?

A conundrum about the chemical make-up of fossilized insects has been solved this week by scientists who baked up scorpions to find the answer.

Modern arthropods, including cockroaches, scorpions, beetles and shrimps, have shells made up of chitin. Chitin consists of stringy carbohydrate fibres rather like plant cellulose that are embedded in a hard protein matrix, with a waxy layer on top. But their fossilized counterparts, explains Neal Gupta of Yale University in New Haven, Connecticut, have an entirely different chemical make-up. Fossils surviving from 30 million years ago have an outside skeleton containing 'aliphatic' molecules with long chains of carbon atoms, very similar in structure to the chemical compound kerogen, a precursor to components of petrol.

'This is an enigma,' says co-author Richard Pancost of Bristol University, UK. 'How do you go from chitin, the carbohydrate, to these long-chain hydrocarbon precursors?'

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Wednesday, July 26, 2006


UF scientists discover evolutionary origin of fins, limbs

Gainesville, Florida: - Performance on the dance floor may not always show it, but people are rarely born with two left feet. We have genes that instruct our arms and legs to grow in the right places and point in the right directions. They also provide for the spaces between our fingers and toes and every other formative detail of our limbs.

Evolutionarily speaking, the genetic instructions used to construct and position our limbs were being perfected more than half a billion years ago in fishes, not along the sides of the body where the fins that preceded human arms and legs sprouted, but at the midline that runs along the backbone and belly.

This midline - think of the dorsal, tail and anal fins of a fish - is where the genetic template to produce fins originated, about 100 million years before paired fins evolved and about 200 million years before paired fins evolved into limbs, according to University of Florida genetics researchers. The findings, published online today in the journal Nature, also provide insight into the evolutionary history of genes involved in human birth defects. [evolution, origin]

[The Nature paper is currently available here but the link won't work for long because it's an advance publication - email if you have any problems.]

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Pre-life molecules present in comets

Ann Arbor, Michigan: Evidence of atomic nitrogen in interstellar gas clouds suggests that pre-life molecules may be present in comets, a discovery that gives a clue about the early conditions that gave rise to life, according to researchers from the University of Michigan and the Harvard-Smithsonian Center for Astrophysics.

The finding also substantially changes the understanding of chemistry in space.

The question of why molecular nitrogen hasn't been detected in comets and meteorites has puzzled scientists for years. Because comets are born in the cold, dark, outer reaches of the solar system they are believed to be the least chemically altered during the formation of the Sun and its planets.

Studies of comets are thought to provide a "fossil" record of the conditions that existed within the gas cloud that collapsed to form the solar system a little more than 4.6 billion years ago. In this cloud, since nitrogen was thought to be in molecular form, and it follows that comets should contain molecular nitrogen as well.

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Scientists discover ancient marine reptiles

A team led by University of Adelaide palaeontologist Dr Benjamin Kear has identified two new species of ancient marine reptiles that swam the shallow waters of an inland sea in Australia 115 million years ago.

Umoonasaurus and Opallionectes belonged to a group of animals called plesiosaurs, long-necked marine reptiles resembling the popular image of the Loch Ness monster, that lived during the time of the dinosaurs.

Dr Kear and his colleagues from the School of Earth and Environmental Sciences and the South Australian Museum identified the new species based on opalised fossils of 30 individuals found in old collections and recent excavations.

The team's findings were recently published in both the international journal Palaeontology (Abstract), and the online edition of Biology Letters, a periodical published by the prestigious Royal Society of London.

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Re: Methane makers yield to science

In a follow-up to Tuesday's Methane makers yield to science, this week's Science Notebook in the Washington Post has the following item Seabed Methane and the Climate:

Abrupt releases of methane trapped in the seabed and sea-bottom ice may be a factor in Earth's historic cycles of warming and cooling, a report in Thursday's online version of the journal Global Biogeochemical Cycles stated.

A team of scientists from the University of California at Santa Barbara based its conclusion on a massive blowout of methane from the ocean floor that was observed and videotaped. The blowout, which took place on March 8, 2002, occurred in an area of gas and oil seepage coming from small volcanoes in the ocean floor of the Santa Barbara channel.

It 'broadens the picture' (so to speak) given by Methane makers yield to science and 'Great lakes' seen on Titan moon found in the title link.

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It's all in the genes

Landmark research shows genetic link to community makeup and ecosystem evolution

It's common knowledge that genes control traits such as eye and hair color. But a large group of scientists from two continents has found that the genes of one organism not only control the characteristics of that individual but also dictate the behavior of thousands of other organisms in a community.

They say these genes, in fact, influence the evolution of an entire ecosystem.

'We're pushing a whole new field of research,' said lead investigator Tom Whitham, Regents Professor of biological sciences at Northern Arizona University.

It's a field that has not been explored before. After all, the idea of looking at the genes of thousands of species in even a simple community is daunting at best.

'What we've done is zero in on a foundation species, because not all species are as equally important ecologically,' Whitham said. The foundation, or key, species in this case is the cottonwood tree, which is the first tree to have all its genes sequenced, or mapped.

Among the genes under study are those that control the level of tannins in cottonwoods, which are dominant trees in riparian habitats in the West. Different individuals, or genotypes, of cottonwoods have different levels of tannins.

These genetically controlled tannin levels drive the structure - or phenotype - of a riparian forest, according to Whitham. Tannins affect the decomposition rate of cottonwood leaves, which in turn affects the fertility of soils, which affects the microbes in the soil, which affect the insects that live in the soil or eat the leaves, which affect the birds that feed on the insects, and so on.

In the July 2007 issue of Nature Reviews Genetics [1] and the May issue of Evolution, Whitham and fellow researchers discuss how this phenotype is heritable on an ecosystem level. That is, the progeny of a tree are likely to support the same communities of organisms and ecosystem processes that their parents supported.

It's a premise with far-reaching implications. Consider, for example, conservation efforts to preserve biodiversity in the face of habitat destruction, climate change and other impacts on the environment. Planting trees that are genetically diverse will result in increased diversity of other species in the dependent community. The greater the tree diversity, the greater the chance of associated species surviving environmental degradation.

"It's not enough to save rare and endangered species. We need to save genetic diversity in the foundation species," said Jennifer Schweitzer, a co-author of the Nature Reviews Genetics paper and postdoctoral researcher at NAU. "Having high genetic diversity in these foundation species is insurance against changes in the future."

The research also has ramifications when it comes to genetically modified organisms and their effects on the landscapes in which they are introduced. For example, grasses that are genetically altered to prevent weed growth could pass that resistance along to exotic plants, which then might take over a community and change the evolution of that ecosystem.

More than 50 researchers from the United States, Canada and Australia are studying this genetic driver of community structure and ecosystem evolution. The work is funded by a 5 million dollar Frontiers in Integrative Biological Research grant from the National Science Foundation. The project includes scientists from a multitude of disciplines because, as Whitham says, "No one person has all the skills to do this."

"This is an exciting project with global impact, drawing on the expertise of geneticists, ecologists, molecular biologists, biogeographers and others," said Chris Greer, program director at the National Science Foundation. "The results are expected to not only shed light on how complex biological communities function but to inform efforts to address the impact of human activities, such as landscape fragmentation, on stressed ecosystems across the planet."

The researchers are the first to study the genetic framework of communities and ecosystems in the wild. They have planted several experimental "common gardens" of cottonwoods in Arizona and Utah. The trees are propagated at NAU's research greenhouse. Through DNA fingerprinting, the scientists know the precise genetic makeup of each tree.

In one experiment, Whitham's group worked with the Bureau of Reclamation to plant about 10,000 trees at the Cibola National Wildlife Refuge along the lower Colorado River, about 20 miles south of Blythe, California, to examine how genetic diversity at the stand level influences communities and ecosystem processes.

"The Bureau of Reclamation gets restoration out of this project, and we get this incredible experiment," said Whitham.

All of the experiments, so far, have exceeded the researchers' expectations. "Initially we thought that the [genetic influences] would be more localized - that the influences would be less genetic and more environmental as we moved beyond the local common garden setting to all of the western U.S." In the end, however, Whitham said, "Plant genes are far more important than we ever expected them to be."

Now the researchers want to know if their findings hold true in different environments around the world. "To understand how important something is, you have to test in multiple locations," Whitham said.

A parallel study in Australia that examines the eucalyptus tree as the foundation species is yielding the same results as the studies on cottonwoods. And Whitham has just returned from South Africa and Borneo in Southeast Asia, where he is planting the seeds for further study.

Source: EurekaAlert/Northern Arizona University PR July 24 2006



[1] A framework for community and ecosystem genetics: from genes to ecosystems

Thomas G. Whitham et al.

Nature Reviews Genetics 7, 510-523 (July 2006) | doi:10.1038/nrg1877

Can heritable traits in a single species affect an entire ecosystem? Recent studies show that such traits in a common tree have predictable effects on community structure and ecosystem processes. Because these 'community and ecosystem phenotypes' have a genetic basis and are heritable, we can begin to apply the principles of population and quantitative genetics to place the study of complex communities and ecosystems within an evolutionary framework. This framework could allow us to understand, for the first time, the genetic basis of ecosystem processes, and the effect of such phenomena as climate change and introduced transgenic organisms on entire communities.

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Tuesday, July 25, 2006


Velvet Worm Brains Reveal Secret Sisterhood With Spiders

Velvet worms, living fossils that look like a child's rendition of caterpillars, are more closely related to spiders and scorpions than to butterflies, according to new research.

Known to scientists as onychophorans, velvet worms have been thought to be similar to the ancestors of modern arthropods, the jointed-legged creatures that includes insects.

Fossils that look very much like today's onychophorans can be found in rocks 540 million years old.

'When I looked at their brains, I was shocked because I didn't expect to see what I saw,' said Nicholas J. Strausfeld of The University of Arizona in Tucson. 'I just felt from their organization that these looked like spider brains, that they had more in common with spider brains than with other arthropod brains.'

Strausfeld, a UA Regents' Professor of neurobiology and the director of UA's Center for Insect Science, is a pioneer in using the architectures of cell arrangements within brains to tease out evolutionary relationships among arthropods, the animal phylum that includes all kinds of creepy crawlies, including insects, crustaceans such as lobsters and crabs, and spiders and scorpions.

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Methane makers yield to science

The genetic code of an important group of methane-producing microbes has been sequenced by German scientists.

The archaea are probably the major source of methane emanating from rice fields, contributing up to a quarter of global emissions of the gas.

The new genomic information reveals how the single-celled organisms have adapted to thrive in paddy soil...

...Rice paddies give off substantial quantities of methane, a potent greenhouse gas; and eight years ago, microbiologists identified what they believed to be the key culprit: a organism group they called Rice Cluster I (RC-I)...

...The archaea are an ancient branch of microbial life on Earth first identified by scientists in 1977.

Many of their species live in extreme environments. 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.

Some researchers hold out hope that some of the methane traces observed on Mars, for example, may be coming from organisms like RC-I.

Also see:

'Great lakes' seen on Titan moon

The Cassini spacecraft has discovered possible evidence for lakes filled with liquid hydrocarbons around the north pole of Saturn's moon Titan.

Cassini: Methane Lakes on Titan Evolution Research

If confirmed, Titan would become the only planetary body other than Earth known to host lakes.

A handful of these dark patches have channels leading in and out of them; these channels have a shape that implies they were carved by a liquid...

...The abundant methane in Titan's atmosphere is stable as a liquid under the moon's freezing conditions, as is the slightly larger molecule ethane. But liquid water is not.

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Plesiosaur named after electrician

A 70 million-year-old plesiosaur may be named after the electrician who discovered it, experts said.

Nigel Armstrong from Doncaster found the marine reptile fossil's skeleton on land south of Filey in 2002.

The 4m-long 'sea dragon' is the first of its age to be found and provides a missing link in its evolution, a Rotunda Geology Group spokeswoman said.

The new species may be named after Mr Armstrong but scientists had yet to make that decision, she added...

Academics from across the world are expected to study the remains of the creature when they go on show at the Scarborough Campus of the University of Hull on 26 July.

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Re: And the Evolutionary Beat Goes On . . .

In the same issue of PLoS Biology that

A Map of Recent Positive Selection in the Human Genome

appears (referred to in the Washington Post article "And the Evolutionary Beat Goes On") is:

Being Positive about Selection

How has language developed in humans and what genetic changes underlie our unique cognitive abilities? Accounts of positive selection that lead to such abilities in humans fascinate us because of the insight they provide into our own evolution, and into the many genetic differences that distinguish us from other apes. The genes that became fixed in our lineage as a result of positive selection are, after all, the ones that make us human. But understanding which gene, or what proportion of a genome, is being driven to fixation by natural selection is of more fundamental biological importance because it can tell us about speciation and the very nature of adaptation.

[Also see the second half of this post]

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Rare Discovery: Fossilized Bone Marrow is 10 Million Years Old

Fossilized Bone Marrow is 10 Million Years Old: Scientists have extracted intact bone marrow from the fossilized remains of 10-million-year-old frogs and salamanders.

The finding, detailed in the August issue of the journal Geology, is the first case of fossilized bone marrow ever to be discovered and only the second report of fossilized soft tissue. In June of 2005, scientists announced they had found preserved red blood cells from a Tyrannosaurus rex leg bone (see here).

'It pushes back the boundary for how far [soft tissue] fossilization can go,' said study leader Maria McNamara of University College Dublin in Ireland.

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Monday, July 24, 2006


ScienceDaily: Atomic-resolution Structure Of A Ribozyme Yields Insights Into RNA Catalysis And The Origins Of Life

Which came first, nucleic acids or proteins? This question is molecular biology's version of the 'chicken-or-the-egg' riddle. Genes made of nucleic acids (DNA or RNA) contain the instructions for making proteins, but enzymes made of proteins are needed to replicate genes. For those who try to understand how life originated, this once seemed an intractable paradox.

The solution came with the discovery 20 years ago that certain types of RNA can act as enzymes, catalyzing reactions just as enzymes made of protein do. This means, in principle, that a single type of molecule, RNA, might be able to both encode information and replicate it. The idea that the first self-replicating molecules in a pre-biotic primordial soup were composed of RNA, known as the 'RNA World' hypothesis, is one of the central tenets upon which many theories of the origin of life are now based.

Research on the structure and function of RNA enzymes, or ribozymes, has been one of the main activities in the Center for the Molecular Biology of RNA at the University of California, Santa Cruz, as well as many other laboratories throughout the world. In addition to offering glimpses into how life may have originated, ribozymes are also being engineered in many academic and industrial laboratories to be therapeutic agents for potential use in fighting infectious and chronic diseases.

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And the Evolutionary Beat Goes On . . .

Washington Post: Stephen Jay Gould would have been pleased.

No, not about his mug shot at the endpoint of evolution in the illustration above, but about the growing evidence that evolution is not just real but is actually happening to human beings right now."

"From 1970 to 2000, there was a widespread view that although natural selection is very important, it is relatively rare," said Jonathan Pritchard, a geneticist at the University of Chicago. "That view was driven largely because we did not have data to identify the signals of natural selection... In the last five years or so, there has been a tremendous growth in our understanding of how much selection there is."

That insight has only deepened as scientists have gained the ability to read the entire human genome, the chain of "letters" that spell out humanity's genetic identity.

"Signals of natural selection are incredibly widespread across the human genome," Pritchard said. "Everywhere we look, there appears to be very widespread signals of natural selection in many genes and many processes."

Pritchard helped write a recent paper that identified some of those changes. The paper was published in the public access journal PLoS Biology:

A Map of Recent Positive Selection in the Human Genome

Abstract: The identification of signals of very recent positive selection provides information about the adaptation of modern humans to local conditions. We report here on a genome-wide scan for signals of very recent positive selection in favor of variants that have not yet reached fixation. We describe a new analytical method for scanning single nucleotide polymorphism (SNP) data for signals of recent selection, and apply this to data from the International HapMap Project.

In all three continental groups we find widespread signals of recent positive selection. Most signals are region-specific, though a significant excess are shared across groups. Contrary to some earlier low resolution studies that suggested a paucity of recent selection in sub-Saharan Africans, we find that by some measures our strongest signals of selection are from the Yoruba population.

Finally, since these signals indicate the existence of genetic variants that have substantially different fitnesses, they must indicate loci that are the source of significant phenotypic variation. Though the relevant phenotypes are generally not known, such loci should be of particular interest in mapping studies of complex traits. For this purpose we have developed a set of SNPs that can be used to tag the strongest (approx) 250 signals of recent selection in each population.

Also see:

Correction: A Map of Recent Positive Selection in the Human Genome


Science: Behavior and Evolution [transcript]:

Washington Post science writer Shankar Vedantam (author of And the Evolutionary Beat Goes On . . .) was online at 3 p.m. ET on Monday, July 24 to discuss the psychology behind our political biases and answer questions about evidence that shows humans are still evolving.

[Follow up article.]

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Sunday, July 23, 2006


Shared ancestor to humans, present-day non-human primates may be linchpin in evolution of language

When contemplating the coos and screams of a fellow member of its species, the rhesus monkey, or macaque, makes use of brain regions that correspond to the two principal language centers in the human brain, according to research conducted by scientists at the National Institute on Deafness and Other Communication Disorders (NIDCD) and the National Institute of Mental Health (NIMH), two of the National Institutes of Health.

The finding, published July 23 in the advance online issue of Nature Neuroscience, bolsters the hypothesis that a shared ancestor to humans and present-day non-human primates may have possessed the key neural mechanisms upon which language was built. Principal collaborators on the study are Allen Braun, M.D., chief of NIDCD's Language Section, Alex Martin, Ph.D., chief of NIMH's Cognitive Neuropsychology Section, and Ricardo Gil-da-Costa, Gulbenkian Science Institute, Oeiras, Portugal, who conducted the study during a three-year joint appointment at the NIDCD and NIMH.

'This intriguing finding brings us closer to understanding the point at which the building blocks of language appeared on the evolutionary timeline,' says James F. Battey, Jr., M.D., Ph.D., director of the NIDCD. 'While the fossil record cannot answer this question for us, we can turn to the here and now - through brain imaging of living non-human primates - for a glimpse into how language, or at least the neural circuitry required for language, came to be.'

While non-human primates do not possess language, they are able to communicate about such things as food, identity, or danger to members of their species by way of vocalizations that are interpreted and acted upon. In humans, the two main regions of the brain that are involved in encoding this type of information in language are known as Broca's area and Wernicke's area, named for the physician-researchers who discovered them. [Evolution of Language]

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Latest Sequencing Targets: Gibbon Genome Sequence To Be Added To Primate Tree

The National Human Genome Research Institute (NHGRI), one of the National Institutes of Health (NIH), today announced several new sequencing targets including the Northern white-cheeked gibbon (Nomascus leucogenys), setting the stage for completing a quest to sequence the genome of at least one non-human primate genome from each of the major positions along the evolutionary primate tree and making available an essential resource for researchers unraveling the genetic factors involved in human health and disease. Comparing the genomes of other species to humans is an exceptionally powerful tool to help researchers understand the working parts of the human genome in both health and illness.

NHGRI's Large-Scale Sequencing Research Network and their international partners have already sequenced - or have been approved to sequence - at high-density coverage the genomes of several non-human primates including the chimpanzee (Pan troglodytes), the rhesus macaque (Macaca mulatta), the orangutan (Pongo pygmaeus), marmoset (Callithrix jacchus) and the gorilla (Gorilla gorilla).

"The gibbon genome sequence will provide researchers with crucial information when comparing it to the human genome sequence and other primate genomes, shedding light on molecular mechanisms implicated in human health and disease - from infectious diseases and neurological disorders to mental illness and cancer," said NHGRI Director Francis S. Collins, M.D., Ph.D.

The gibbon genome is unique because it carries an extraordinary high number of chromosome rearrangements, even when compared to other primates.

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A big to-do over Kansas 'Dodos'

"Flock of Dodos," a tongue-in-cheek documentary about the evolution vs. intelligent design fight in Kansas schools, will hit movie theaters this fall. Soon after a big home video push.

Cosmic Films will distribute the movie theatrically beginning with an eight-city push this fall, said filmmaker/scientist/Kansas City native Randy Olson, who was in town recently visiting his mother, Lake Quivira resident (and featured "Dodos" player) Muffy Olson. The initial run will include New York, Chicago, Los Angeles, San Francisco, Seattle and Washington, D.C.

"Dodos" was a big hit at this spring's Tribeca Film Festival in New York City. It will also be the closing-night movie (on Sept. 21) for this year's Kansas International Film Festival at the Glenwood Arts Theatre.

Early next year the film will be released on DVD, and that, said Olson, "is where the money is."

He anticipates science teachers will want to use it as an instructional tool."

Featured book: "Flock of Dodos: Behind Modern Creationism and Intelligent Design" (Amazon UK | US)

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Darwin's steps map flower changes

Three generations of Charles Darwin's descendants have replicated their great grandfather's 150-year-old survey near his old home, Down House, in Kent.

Between then and now, the number of plant species in Great Pucklands meadow has declined by 15%.

Changes in farm practice are believed to be behind the decline.

Darwin's observations in the meadow contributed to the development of the natural selection theory in his seminal book On The Origin of Species.

Darwin recorded 142 plant species in the meadow, which is just behind Down House, in 1855.

'While scientists tend to focus on rare or unusual species, we have studied what is in essence a rather ordinary piece of grassland,' said Johannes Vogel, keeper of botany at the Natural History Museum, one of the scientists involved in replicating the study.

'It is this ordinariness that makes it significant.'

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