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domingo, 6 de febrero de 2011

Secret Life of Bees Now a Little Less Secret


ScienceDaily (Feb. 6, 2011) — Many plants produce toxic chemicals to protect themselves against plant-eating animals, and many flowering plants have evolved flower structures that prevent pollinators such as bees from taking too much pollen. Now ecologists have produced experimental evidence that flowering plants might also use chemical defences to protect their pollen from some bees.

The results are published next week in the British Ecological Society's journal Functional Ecology.

In an elegant experiment, Claudio Sedivy and colleagues from ETH Zurich in Switzerland collected pollen from four plant species -- buttercup, viper's bugloss, wild mustard and tansy -- using an ingenious method. Instead of themselves collecting pollen from plants, the researchers let bees do the leg work, harvesting pollen from the nests of specialist bees which only feed on one type of plant.

They then fed the pollen from each of the four plants to different broods of the larvae of two closely-related generalist species of mason bee (Osmia bicornis and Osmia cornuta) to see how well the larvae developed.

They found that despite the fact that the two generalist mason bees have a wide diet of different pollens, they showed striking differences in their ability to develop on pollen from the same plant species.

According to Claudio Sedivy: "While the larvae of Osmia cornuta were able to develop on viper's bugloss pollen, more than 90% died within days on buttercup pollen. Amazingly, the situation was exactly the opposite with the larvae of Osmia bicornis. And both bee species performed well on wild mustard pollen, while neither managed to develop on tansy pollen."

"As far as we know, this is the first clear experimental evidence that bees need physiological adaptations to cope with the unfavourable chemical properties of certain pollen," he says.

Plants would have good reason to protect their pollen against bees. Bees need enormous amounts of pollen to feed their young, pollen that could otherwise be used by the plants for pollination. The pollen of up to several hundred flowers is needed to rear one single larva, and bees are very efficient gatherers of pollen, often taking 70-90% of a flower's pollen in one visit. Because they store this pollen in special hairbrushes or in their gut, this means the pollen is not used to pollinate the flower.

Sedivy explains: "Bees and plants have conflicting interests when it comes to pollen. While most plants offer nectar to visiting insects as a bait for insects to transport the pollen from flower to flower, bees are very efficient pollen collectors. Therefore, plants have evolved a great variety of morphological adaptations to impede bees from depleting all their pollen. This study provides strong evidence that pollen chemistry might be at least as important as flower morphology to constrain pollen loss to bees."

Diego Efrain Quintero Gámez C.I. v.-18.879.989

Asignatura: Electrónica del Estado Sólido

Fuente:http://www.sciencedaily.com/releases/2011/02/110201122238.htm

Turtle Populations Affected by Climate, Habitat Loss and Overexploitation


ScienceDaily (Feb. 2, 2011) — The sex of some species of turtles is determined by the temperature of the nest: warm nests produce females, cooler nests, males. And although turtles have been on the planet for about 220 million years, scientists now report that almost half of the turtle species is threatened. Turtle scientists are working to understand how global warming may affect turtle reproduction. To bring attention to this and other issues affecting turtles, researchers and other supporters have designated 2011 as the Year of the Turtle.

Why should we be concerned about the loss of turtles?

"Turtles are centrally nested in the food web and are symbols of our natural heritage. They hold a significant role in many cultures. For example, in many southeast Asian cultures turtles are used for food, pets, and medicine," explains Deanna Olson, a research ecologist and co-chair of the Partners in Amphibian and Reptile Conservation steering committee spearheading the Year of the Turtle campaign.

Turtles (which include tortoises) are central to the food web. Sea turtles graze on the sea grass found on the ocean floor, helping to keep it short and healthy. Healthy sea grass in turn is an important breeding ground for many species of fish, shellfish, and crustaceans. The same processes hold for freshwater and land turtles. For example, turtles contribute to the health of marshes and wetlands, being important prey for a suite of predators. The Year of the Turtle activities, include a monthly newsletter showcasing research and conservation efforts, education and citizen science projects, turtle-themed art, literature, and cultural perspectives, says Olson, a scientist with the Forest Service's Pacific Northwest Research Station.

Olson also co-authored a report, "State of the Turtle," and created a new turtle mapping project for the United States. The report is being translated into other languages for use here and around the world.

"A French translation of the report is already completed, and groups from Bangladesh and Germany signed on recently to help promote turtle conservation, and new partners join us each week," explains Olson.

Here are a few quick facts about turtles:

  • About 50 percent of freshwater turtle species are threatened worldwide, more than any other animal group.
  • About 20 percent of all turtle species worldwide are found in North America.
  • Primary threats to turtles are habitat loss and exploitation.
  • Climate change patterns, altered temperatures, affected wetlands and stream flow all are key factors that affect turtle habitats.
  • Urban and suburban development causes turtles to be victims to fast-moving cars, farm machinery; turtles can also be unintentionally caught in fishing nets.

What can be done to conserve turtle populations?

  • Protect rare turtle species and their habitats.
  • Manage common turtle species and their habitats so they may remain common.
  • Manage crisis situations such as acute hazards (i.e., oil spills) and rare species in peril.

To read the report and learn more about the Year of the Turtle and how you can participate, please visit http://www.parcplace.org/yearoftheturtle.htm

Diego Efrain Quintero Gámez C.I. v.-18.879.989

Asignatura: Electrónica del Estado Sólido

Fuente:http://www.sciencedaily.com/releases/2011/02/110202102117.htm

In Tiny Fruit Flies, Researchers Identify Metabolic 'Switch' That Links Normal Growth to Cancer

ScienceDaily (Feb. 2, 2011) — As day-old embryos, fruit flies called Drosophila enter a stage in which their cells freely divide and proliferate as the insect grows dramatically in size.

This is true for all animals, which undergo most of their growth prior to sexual maturation. Until now, researchers have known nothing about the metabolic state that occurs when cells divide during early development. But in a study published online Feb. 1, 2011, in Cell Metabolism, University of Utah human genetics researchers show that this cell division in Drosophiladepends on a metabolic state much like when cells run amok to form cancerous tumors. Unlike cancer, however, this cell proliferation in fruit flies and other organisms halts when the animal becomes mature.

Led by Carl S. Thummel, Ph.D., professor of human genetics, the researchers identified a genetic switch that supports cell division and proliferation in growing fruit flies. This switch is controlled by a nuclear receptor and transcription factor (proteins that turn genes on and off) called dERR, which is similar to three human transcription factors known as ERRs (Estrogen-Related Receptors). Two of the ERR transcription factors are associated with breast cancer, leading Thummel to believe that understanding the role of dERR could shed light on how cancer cells proliferate and spread in humans using a metabolic state known as the Warburg effect.

"No one has ever really thought about the metabolic state that supports normal growth during development, or how it might be related to the cell proliferation in cancer," Thummel said. "Our study has a direct relevance for humans. Our findings with dERR suggest that the mammalian transcription factors are doing the same thing."

Although there is probably more than one regulator controlling the metabolic state of cell division and proliferation, identifying the role of dERR is a significant first step in understanding this process. Thummel's study shows that dERR supports cell proliferation by regulating metabolism, the essential function by which people, fruit flies, and other organisms store and use nutrients appropriately.

In fully developed humans and fruit flies most cells are in a metabolic state of homeostasis, where nutrients are used to support normal daily life. To maintain this state, cells turn carbohydrates into ATP, the molecule that is the main source of energy for all organisms. During early development, however, cells must divide and proliferate to form the organs and other tissues that will keep the mature organism alive. To accomplish this, the embryo's metabolic state changes so that instead of producing only ATP, cells use carbohydrates to make proteins, lipids, and nucleotides that support the cell division and proliferation needed for growth.

Employing the method of gene silencing in Drosophilapioneered by the U of U's Kent Golic, Ph.D., professor of biology, Thummel and his colleagues in the U human genetics department discovered that dERR plays a central role inDrosophila development by switching on a set of metabolic genes that allow cells to divide and proliferate. When the researchers silenced dERR in fruit fly embryos at the stage when cells are starting to divide furiously, metabolism was disrupted, growth was stopped, and the insects died. That's a compelling argument for the important role Estrogen-Related Receptors play in metabolism, cell proliferation, and, quite possibly, human cancer, according to Thummel.

"The whole metabolic program of the animal is changed when dERR is removed," he said. "It's pretty remarkable that this one transcription factor turns on an entire program that supports growth."

The Warburg effect is similar to the metabolic state of the fruit fly embryos. Instead of using nutrients to make ATP, they make biomass to divide and proliferate without control. A number of studies have shown a close association between ERR receptors and cancer, and Thummel and his colleagues have provided a new context for studying those receptors in mammals.

"Our studies of the single Drosophila ERR family member raise the important possibility that mammalian ERRs control the dramatic cellular proliferation associated with cancer through their ability to promote the Warburg effect," the researchers write.

Future studies in the Thummel lab are directed toward understanding how dERR knows when to switch on the metabolic state that supports growth. They also want to understand if it has other functions later in life, when the adult animal is in a state of homeostasis.

Along with Thummel, the study's co-authors are first author Jason M. Tennessen, Keith D. Baker, Geanette Lam, and Janelle Evans. Baker, formerly at the U of U Human Genetics Department, is now at the Virginia Commonwealth University School of Medicine Department of Biochemistry and Molecular Biology. The other co-authors are Research Specialists at the U Department of Human Genetics.

Diego Efrain Quintero Gámez C.I. v.-18.879.989

Asignatura: Electrónica del Estado Sólido

Fuente:http://www.sciencedaily.com/releases/2011/02/110201122232.htm

Water Flea: First Crustacean Genome Is Sequenced


ScienceDaily (Feb. 3, 2011) — The ubiquitous freshwater "water flea," Daphnia pulex, may be too small to see, but it has amply proven its value as an "sentinel species" for the presence of toxins and pollutants in the environment.

Daphnia's response to exposure to toxic metals and other chemical pollutants is well studied, and this information is routinely used by groups such as the US Environmental Protection Agency (EPA) to define regulatory limits, and to monitor industrial and municipal discharges.

This week, Daphnia pulex is receiving an enormous pat on the back from the scientific community: It is the first crustacean to have its complete genome sequenced. The sequence is being published February 4 in the journal Science by members of the Daphnia Genomics Consortium, an international network of scientists led by the Center for Genomics and Bioinformatics at Indiana University-Bloomington and the Department of Energy's Joint Genome Institute.

Joshua Hamilton, senior scientist and chief academic and scientific officer at the Marine Biological Laboratory (MBL) in Woods Hole, Mass., is co-author of an important companion paper to the Daphnia genome sequence. That paper, published in 2007, was the first study of the genetic basis for Daphnia's adaptive response to sub-lethal levels of a major environmental contaminant, the metal cadmium. Cadmium, which is highly toxic to aquatic life (and to humans), is one of the most common contaminants found in the U.S. EPA Superfund sites.

The technologies described in the 2007 paper (cDNA microarrays) were the first genomic tools developed for Daphniaand they are applicable to testing Daphnia's genetic response to a wide range of environmental contaminants. Subsequently, many other environmental stressors have been tested usingDaphnia.

"Daphnia can serve as an important 'canary in a coal mine' for freshwater ecosystems and their response to environmental contamination," says Hamilton. "When the Daphnia population is impacted, it is likely that the entire ecosystem is being adversely affected and may be on the verge of collapse."

Hamilton, then at Dartmouth Medical School, and colleagues at Dartmouth and Indiana University demonstrated that Daphniacan adapt to increasing levels of cadmium by up-regulating a unique version of a key protective molecule called metallothionein, but at a very high cost. Although the individuals could resist the high levels of cadmium and survive, their reproductive success plummeted to a fraction of that of animals in uncontaminated waters, which after only a few generations threatened the entire population's long-term survival.

Daphnia is emerging as a model organism for a new field of science -- environmental genomics -- that aims to better understand how the environment and genes interact. Scientific developments from this field can be used to manage our water resources and protect human health from chemical pollutants in the environment, and serve as a way to understand how our own bodies respond to these environmental challenges.

"Until now, Daphnia has primarily been used as sentinel species for monitoring the integrity of aquatic ecosystems," says Joseph Shaw, co-author of the cadmium study (as a former postdoctoral fellow with Hamilton), co-author of the new Science paper, and now a biologist at Indiana University-Bloomington's School of Public and Environmental Affairs. "But with many shared genes between Daphnia and humans, we will now also apply Daphnia as a surrogate model to address issues directly related to human health. This puts us in a position to begin integrating studies of environmental quality with research of human diseases."

Diego Efrain Quintero Gámez C.I. v.-18.879.989

Asignatura: Electrónica del Estado Sólido

Fuente: http://www.sciencedaily.com/releases/2011/02/110203141824.htm

Animal With the Most Genes? A Tiny Crustacean


ScienceDaily (Feb. 3, 2011) — Complexity ever in the eye of its beholders, the animal with the most genes -- about 31,000 -- is the near-microscopic freshwater crustacean Daphnia pulex, or water flea. By comparison, humans have about 23,000 genes.Daphnia is the first crustacean to have its genome sequenced.

The findings are part of a comprehensive report in the journalScience by members of the Daphnia Genomics Consortium, an international network of scientists led by the Center for Genomics and Bioinformatics (CGB) at Indiana University Bloomington and the U.S. Department of Energy's Joint Genome Institute. A bullet-point list of the Science paper's most important findings appears at the end of this release.

"Daphnia's high gene number is largely because its genes are multiplying, by creating copies at a higher rate than other species," said project leader and CGB genomics director John Colbourne. "We estimate a rate that is three times greater than those of other invertebrates and 30 percent greater than that of humans."

Daphnia Genomics Consortium projects can be found athttp://daphnia.cgb.indiana.edu, as well as a link to the nearly 40 companion papers based on the data reported in theScience paper.

Scientists have studied Daphnia for centuries because of its importance in aquatic food webs and for its transformational responses to environmental stress. Predators signal some of the animals to produce exaggerated spines, neck-teeth or helmets in self-defense. And like the virgin nymph of Greek mythology that shares its name, Daphnia thrives in the absence of males -- by clonal reproduction, until harsh environmental conditions favor the benefits of sex.

Daphnia's genome is no ordinary genome.

"More than one-third of Daphnia's genes are undocumented in any other organism -- in other words, they are completely new to science," says Don Gilbert, coauthor and Department of Biology scientist at IU Bloomington.

Sequenced genomes often contain some fraction of genes with unknown functions, even among the most well-studied genetic model species for biomedical research, such as the fruit fly Drosophila. By using microarrays (containing millions of DNA strands affixed to microscope slides) that are made to measure the conditions under which these new genes are transcribed into precursors for proteins, experiments that subjectedDaphnia to environmental stressors point to these unknown genes having ecologically significant functions.

"If such large fractions of genomes evolved to cope with environmental challenges, information from traditional model species used only in laboratory studies may be insufficient to discover the roles for a considerable number of animal genes," Colbourne said.

Daphnia is emerging as a model organism for a new field of science -- Environmental Genomics -- that aims to better understand how the environment and genes interact. This includes a practical need to apply scientific developments from this field toward managing our water resources and protecting human health from chemical pollutants in the environment.

James E. Klaunig, professor and chair of the School of Health, Physical Education, and Recreation's Department of Environmental Health at IU Bloomington, predicts the present work will yield a more realistic and scientifically-based risk evaluation.

"Genome research on the responses of animals to stress has important implications for assessing environmental risks to humans," Klaunig said. "The Daphnia system is an exquisite aquatic sensor, a potential high-tech and modern version of the mineshaft canary. With knowledge of its genome, and using both field sampling and laboratory studies, the possible effects of environmental agents on cellular and molecular processes can be resolved and linked to similar processes in humans."

The scientists learned that of all sequenced invertebrate genomes so far, Daphnia shares the most genes with humans.

The idea behind environmental genomics for risk assessment is fairly simple. Daphnia's gene expression patterns change depending on its environment, and the patterns indicate what state its cells are in. A water flea bobbing in water containing a chemical pollutant will express by tuning-up or tuning-down a suite of genes differently than its clonal sisters accustomed to water without the pollutant. Importantly, the health effects of most industrially produced compounds at relevant concentrations and mixtures in the environment are unknown, because current testing procedures are too slow, too costly, and unable to indicate the causes for their effects on animals, including human. The new findings suggest that Daphnia's research tools (like microarrays) and genome information can provide a higher-throughput and information-rich method of measuring the condition of our water supply.

"Until now, Daphnia has primarily been used as sentinel species for monitoring the integrity of aquatic ecosystems," said Joseph Shaw, coauthor and IU School of Public and Environmental Affairs biologist. "But with many shared genes between Daphnia and humans, we will now also apply Daphniaas a surrogate model to address issues directly related to human health. This puts us in a position to begin integrating studies of environmental quality with research of human diseases."

A requisite for reaching model system status is a large research community that contributes to its growing body of knowledge and resources. Over the course of the project, the Daphnia Genomics Consortium has grown from a handful of founding members to more than 450 investigators distributed around the globe. Nearly 200 scientists have contributed published work resulting from the genome study, many in open-source journals published as a thematic series by BioMedCentral.

A list of these publications can be found athttp://www.biomedcentral.com/series/Daphnia.

"Assembling so many experts around a shared research goal is no small feat," said Peter Cherbas, director of the CGB. "We're obviously proud of the CGB's catalytic role. The genome project signals the coming-of-age of Daphnia as a research tool for investigating the molecular underpinnings of key ecological and environmental problems."

Colbourne agreed, adding, "New model systems rarely arrive on the scene with such clear and important roles to play for advancing a new field of science."

The scientists present findings on the pace at which copied genes gain new functions, including a novel theory that accounts for the apparent rapid evolution of some of Daphnia's gene families (suites of related genes that result from repeated duplication events).

"Gene functions can become distinct very quickly," said Michael Pfrender, coauthor and associate professor of biology at the University of Notre Dame. "We had all assumed that newly copied genes that code for the same proteins would initially have the same functions, and that new functions evolve slowly with age, by acquiring rare beneficial mutations. Instead, we found that half of the newly copied genes had changed their expression very soon, possibly at the time of their origin."

Like in a mystery novel, the DNA evidence presented by examining the patterns of gene duplication in the study's first chapters was combined with clues of the genes' functions in later chapters to propose a new model for how genes accumulate in genomes.

"The smoking gun in this investigation was clear," said Kelley Thomas, coauthor and Hubbard Professor in Genomics at the University of New Hampshire. "A high rate of gene duplication, which produces a steady pool of new genes that have different expressions can facilitate the preservation of some gene-copies by natural selection."

Like most theories for how new genes evolve, their common fate is to wither by disabling mutations. For a new gene to persist, its function must give an advantage to the organism -- and the earlier the better for the gene to avoid bad mutations. InDaphnia's case, there seems to be a sufficiently large pool of young gene copies that some will be expressed in novel circumstances, and by chance be compatible with expression patterns of interacting genes required to perform its new function.

"At first glance, amplified gene families in Daphnia are more likely to be functionally related than not," said Michael Lynch, coauthor and distinguished professor of biology at IU Bloomington. "This suggests that gene functions via duplication often evolve in cooperation with other genes in the genome. We are not yet prepared to generalize our findings until we broaden our investigation to include more Daphnia lineages having different population histories. However, it's quite clear that this genome project opens up enormous opportunities that are not readily accomplished using other models with poorly understood -- and not terribly accessible -- ecologies."

So what other reasons might Daphnia have so many genes compared to other animals? The coauthors of the Science paper begin addressing that issue as well as others related to the genomic architecture and evolution of the species.

"We don't yet have final answers," Pfrender said. "The sequenced isolate did originate from a naturally inbred population, which may contribute to some features of this genome -- and Daphnia's partial asexuality may have a hand to play."

Another possibility, Colbourne said, is that "since the majority of duplicated and unknown genes are sensitive to environmental conditions, their accumulation in the genome could account for Daphnia's flexible responses to environmental change."

This work received financial and material support from the Office of Science of the U.S. Department of Energy, the National Science Foundation, Lilly Endowment Inc., Roche NimbleGen Inc., the National Institutes of Health, the U.S. Department of Health and Human Services, and Indiana University.

Major Findings

  • Largest inventory of genes ever recorded for a sequenced animal, packaged within a tiny genome of only 200 million bases.
  • The genome is made compact by the reduction in size of spaces (introns) between the gene parts that code for proteins.
  • First crustacean genome sequenced. Only 4.5 percent of genes are shared exclusively between Daphnia and insects, arthropods which shared a common ancestor some 500 million years ago.
  • First time an arthropod with a wholly aquatic life cycle has had its genome sequenced. Genes shared by Daphnia and unrelated aquatic vertebrates are identified, and are likely key for living life in water.
  • Genes that have unknown functions -- because they are uniquely identified in Daphnia -- are involved in response to the environment.
  • Of all sequenced genomes belonging to the animal group composed of insects and crustaceans, Daphnia share more genes with humans.
  • The birth rates for genes can be high -- duplications occur three times more in Daphnia pulex than in other invertebrates -- and duplicated genes are more likely to be functionally related than not.
  • Newly duplicated genes can rapidly acquire new functions, which are best identified by specific environmental conditions.
  • Daphnia-specific gene families that have amplified to large numbers include hemoglobins (11 copies), and opsin (visual) genes (46 copies) -- a very old and newly discovered expanded subfamily of opsins was lost in terrestrial animal lineages.
  • The overall data suggest an original hypothesis for how newly duplicated genes are retained in the genome, which depends on the condition-specific regulation of cooperatively evolving genes.

Diego Efrain Quintero Gámez C.I. v.-18.879.989

Asignatura: Electrónica del Estado Sólido

Fuente: http://www.sciencedaily.com/releases/2011/02/110203141812.htm

Sentinel of Change: Waterflea Genome to Improve Environmental Monitoring Capabilities


ScienceDaily (Feb. 3, 2011) — A tiny crustacean that has been used for decades to develop and monitor environmental regulations is the first of its kind to have its genetic code sequenced and analyzed -- revealing the most gene-packed animal characterized to date. The information deciphered could help researchers develop and conduct real-time monitoring systems of the effects of environmental remediation efforts.

Considered a keystone species in freshwater ecosystems, the waterflea, Daphnia pulex, is roughly the size of the equal sign on a keyboard. Its 200 million-base genome was described in the February 4 issue of Science, the result of a collaboration between theDaphnia Genomics Consortium and the U.S. Department of Energy (DOE) Joint Genome Institute (JGI) that began nearly a decade ago when environmental agencies and toxicology researchers were looking into aquatic model systems that acted as sentinel species in order to diagnose the presence of problematic chemicals in fresh water and extrapolate their effects.

"Daphnia is one of the most widely used model systems for environmental protection agencies around the world," said project leader and Indiana University Center for Genomics and Bioinformatics genomics director John Colbourne. "The costly challenge of evaluating conditions in the environment and of our water supplies may be overcome by Daphnia's potential use as a high-tech and modern version of the mineshaft canary. An early detector of environmental risks should produce diagnostic and robust signals of the test-animal's response to stress. Our initial studies revealed that Daphnia's genes are evolved to be fine-tuned to environmental changes."

The ability to use Daphnia for environmental studies focused on identifying associations between gene function and disease also contributed to the recent inclusion of Daphnia as a model system for biomedical research by the National Institutes of Health, joining established models like the fruit fly Drosophilaand the worm C. elegans. Colbourne said that the DaphniaGenomics Consortium is working on improving techniques to do large-scale genome population assays to better track and manage remediation applications.

Aside from environmental monitoring, study coauthor Michael Pfrender of the University of Notre Dame noted another application of the Daphnia genome with regard to developing commercial biofuels. "When you grow algae in large open-air tanks to select for biofuel production, they're invaded byDaphnia that graze down the algae," he said. "You're faced with either learning how to control Daphnia or learning how to use it to harvest the hydrocarbons."

The Daphnia project has spawned a large research community that has grown over the course of the project from a handful of founding members to over 450 investigators distributed around the globe. Nearly 200 scientists have contributed published work resulting from the genome study.

The waterflea was sequenced and annotated at the DOE JGI. Igor Grigoriev, head of the DOE JGI Eukaryotic Genomics group, noted that the Daphnia genome, which was sequenced using the Sanger method, is the most compact with over 31,000 genes, a third of which are of unknown function. Grigoriev attributed the large number of genes to expansion by tandem duplication, adding that the number is a conservative estimate. "There are more genes in Daphnia than there are in the human genome, more than any animal," he said.

From the perspective of tracking a species' evolution and development or phylogenetics, the Daphnia genome allows researchers a glimpse at a branch of the Arthropod phylum that had been left out until now when conducting comparative genomic studies without the group. While sequences of arthropods such as the honeybee (Apis mellifera) and the fruit fly (Drosophila melanogaster) are available, there was no representative from the crustaceans in the phylum.

"Crustaceans are the closest living relatives to insects, andDaphnia pulex is the first animal from this group to have its genome completely sequenced," said Jeffrey Boore, who led the portion of this project done at the DOE Joint Genome Institute and is now CEO of Genome Project Solutions, which also made contributions to this study.

Annotating the Daphnia genome also afforded researchers an alternate way of determining gene functions. "This goes beyond having the first crustacean genome," said Grigoriev. "By combining functional genomics assays we can see that the genes of unknown function -- the new genes resulting from adaptations, not the ones conserved because they're key for housekeeping -- are the most responsive to environmental changes. In that sense, the organism's environment can direct us to areas of interest; if you pick a genome and would like to annotate all the genes, go to the environment."

Diego Efrain Quintero Gámez C.I. v.-18.879.989

Asignatura: Electrónica del Estado Sólido

Fuente: http://www.sciencedaily.com/releases/2011/02/110203141822.htm

Lampreys Give Clues to Evolution of Immune System


ScienceDaily (Feb. 3, 2011) — Biologists have discovered that primitive, predatory lampreys have structures within their gills that play the same role as the thymus, the organ where immune cells called T cells develop in mammals, birds and fish.

The finding suggests that in vertebrate evolution, having two separate organs for immune cell development -- the bone marrow for B cells and the thymus for T cells -- may have preceded the appearance of the particular features that mark those cells, such as antibodies and T cell receptors.

The results will be published Feb. 3 by the journal Nature.

The first author of the paper is postdoctoral fellow Baubak Bajoghli at the Max Planck Institute of Immunobiology and Epigenetics in Freiburg, Germany. The co-senior authors are Thomas Boehm, MD, group leader at the Max Planck Institute, and Max Cooper, MD, professor of pathology and laboratory medicine at Emory University School of Medicine and the Emory Vaccine Center, and a Georgia Research Alliance Eminent Scholar.

"Our research has allowed us to see that lampreys have cells that resemble our T cells and B cells, but until recently, we didn't know where they developed or much about how," says Cooper, who made pioneering studies of the "two-arm" nature of the immune system, including defining the role of the thymus, at the University of Minnesota in the 1960s.

"We can now assume that the lamprey has a dual immune defense system similar to that of humans," says Boehm.

For commercial and recreational fishermen, lampreys represent a threat. For biologists, lampreys represent an opportunity to envision the evolutionary past, because of their status as "living fossils" that haven't changed in millions of years. Lampreys are thought to be an early offshoot on the evolutionary tree, before sharks and fish. Their lack of jaws distinguishes them from sharks or other types of fish.

Despite their primitive nature, lampreys do have a surprisingly sophisticated immune system. Blood cells develop in lampreys' typhlosole, an organ that lies next to the intestine. Lampreys have proteins in their blood that grab on to invaders like our antibodies, but structurally, those proteins don't look like antibodies.

Mammals, birds and fish have two types of immune cells, which each develop in separate places. B cells, which produce antibodies, develop in the bone marrow and fetal liver, while T cells, which recognize their targets by cell-to-cell contact, develop in the thymus. In humans, the thymus is located in the upper chest, under the throat.

The vertebrate thymus is a place where developing T cells must "sink or swim," because immature T cells must rearrange certain genes as part of their development. Most of the cells die because the rearrangement process is imprecise, and cells with improperly rearranged genes are screened out. The Emory/Max Planck team discovered that this same type of screening of non-functional genes appears to be occurring in the lamprey "thymoids" located in the tips of the gill filament.

"We don't know much about how this process is happening, but we were able to show that functional copies are found in the blood, while non-functional copies are only found in the thymoid," Cooper says.

In addition, in cells lining both the vertebrate thymus and lamprey thymoid, a gene is turned on (FOXN1) that is essential for thymus development in mice and humans, the scientists found. Mice that have this gene mutated lack a thymus and are called "nude" mice because they have no hair.

"Taken together, the results suggest that this basic feature of the immune system, where two types of cells develop in separate places, may have evolved before jawed and jawless vertebrates split onto different paths," Cooper says. "Having two companion arms of the immune system may be important so that the two arms can regulate each other and prevent autoimmunity."

The research was supported by the Max-Planck Society, the German Research Foundation, the National Institutes of Health and the Georgia Research Alliance.

Diego Efrain Quintero Gámez C.I. v.-18.879.989

Asignatura: Electrónica del Estado Sólido

Fuente: http://www.sciencedaily.com/releases/2011/02/110202132340.htm

¿Una serpiente voladora?


Algunas no necesitan de un avión para volar como en la conocida película. La serpiente del árbol paraíso Chrysopelea paradisi también llamadaserpiente voladora lanza su cuerpo elegantemente desde lo alto de los árboles. Este comportamiento resulta extraño si tenemos en cuenta que las no tienen extremidades para sujetarse ni para controlar sus movimientos en el aire como si fuesen alas.

Estas y su particular forma de moverse son conocidas desde hace tiempo, pero nunca se ha podido comprender los patrones de vuelo ni el despegue de las desde la cima de los árboles. Recientemente se han realizado nuevas investigaciones que parecen revelar estos misteriosos comportamientos.

Jake Socha, un profesor de ciencia de la ingeniería y mecánica del Instituto Virginia Tech y sus colegas experimentaron con , eran inducidas a trepar a lo alto de una torre de 15 metros y saltaban mientras el equipo de filmación captaba sus movimientos mediante 4 cámaras de video.

Las conclusiones a las que llegaron son que las , en lugar de una caída suave conocida como deslizamiento de equilibrio que se da en todas las aves, se arrojaban con movimientos ondulatorios y frenéticos en el aire.

El comportamiento de las en el aire es bastante peculiar, como espasmos nerviosos que contraen una y otra vez el cuerpo del animal. Se dedujo que de esta manera, intentan disminuir la velocidad de caída y el ángulo de deslizamiento.

La serpiente es empujada hacia arriba a pesar de que esta cayendo en el vacío, esto es por los movimientos violentos ondulatorios que hacen que la serpiente prácticamente “vuele” en el aire.

Hipotéticamente esto significa una hazaña casi imposible para una serpiente, sin embargo, los modelos de los patrones de movimiento revelan que en su hábitat natural, donde los árboles son mucho mas altos y las distancias más largas, estas voladoras sin alas pueden permanecer en el aire por mucho tiempo y trasladarse de un árbol a otro.

Diego Efrain Quintero Gámez C.I. v.-18.879.989

Asignatura: Electrónica del Estado Sólido

Fuente:http://www.ojocientifico.com/2010/11/24/serpiente-voladora/

Rare Insect Fossil Reveals 100 Million Years of Evolutionary Stasis


ScienceDaily (Feb. 4, 2011) — Researchers have discovered the 100 million-year-old ancestor of a group of large, carnivorous, cricket-like insects that still live today in southern Asia, northern Indochina and Africa. The new find, in a limestone fossil bed in northeastern Brazil, corrects the mistaken classification of another fossil of this type and reveals that the genus has undergone very little evolutionary change since the Early Cretaceous Period, a time of dinosaurs just before the breakup of the supercontinent Gondwana.

The findings are described in a paper in the open access journal ZooKeys.

"Schizodactylidae, or splay-footed crickets, are an unusual group of large, fearsome-looking predatory insects related to the true crickets, katydids and grasshoppers, in the order Orthoptera," said University of Illinois entomologist and lead author Sam Heads, of the Illinois Natural History Survey. "They get their common name from the large, paddle-like projections on their feet, which help support their large bodies as they move around their sandy habitats, hunting down prey."

Although the fossil is distinct from today's splay-footed crickets, its general features differ very little, Heads said, revealing that the genus has been in a period of "evolutionary stasis" for at least the last 100 million years.

Other studies have determined that the region where the fossil was found was most likely an arid or semi-arid monsoonal environment during the Early Cretaceous Period, Heads said, "suggesting that the habitat preferences of Schizodactylushave changed little in over 100 million years."


Diego Efrain Quintero Gámez C.I. v.-18.879.989

Asignatura: Electrónica del Estado Sólido

Fuente: http://www.sciencedaily.com/releases/2011/02/110203113758.htm

Ants Have Big Impact on Environment as 'Ecosystem Engineers'


ScienceDaily (Feb. 4, 2011) — Research by the University of Exeter has revealed that ants have a big impact on their local environment as a result of their activity as 'ecosystem engineers' and predators.

The study, published in the Journal of Animal Ecology, found that ants have two distinct effects on their local environment.

Firstly, through moving of soil by nest building activity and by collecting food they affect the level of nutrients in the soil. This can indirectly impact the local populations of many animal groups, from decomposers such asCollembola, to species much higher up the food chain.

Secondly, they prey on a wide range of other animals, including larger prey which can be attacked by vast numbers of ant workers.

Dirk Sanders, an author of the study from the university's Centre for Ecology and Conservation, said: "Ants are very effective predators which thrive in huge numbers. They're also very territorial and very aggressive, defending their resources and territory against other predators. All of this means they have a strong influence on their surrounding area.

"In this research, we studied for the first time how big this impact is and the subtleties of it. What we found is that despite being predators, their presence can also lead to an increase in density and diversity of other animal groups. They genuinely play a key role in the local environment, having a big influence on the grassland food web."

The study, carried out in Germany, studied the impact of the presence of different combinations and densities of black garden ants (Lasius niger) and common red ants (Myrmica rubra), both species which can be found across Europe, including in the UK.

It found that a low density of ants in an area increased the diversity and density of other animals in the local area, particularly the density of herbivores and decomposers. At higher densities ants had no or the opposite effect, showing that predation is counteracting the positive influence.

Dr Frank van Veen, another author on the study, said: "What we find is that the impact of ants on soil nutrient levels has a positive effect on animal groups at low levels, but as the number of ants increases, their predatory impacts have the bigger effect -- thereby counteracting the positive influence via ecosystem engineering."

This research was financially supported by the German Research Council.


Diego Efrain Quintero Gámez C.I. v.-18.879.989

Asignatura: Electrónica del Estado Sólido

Fuente: http://www.sciencedaily.com/releases/2011/01/110131133227.htm