Surgimento de um código na polimerização de aminoácidos ao longo de 'templates' de RNA

domingo, fevereiro 28, 2010

Emergence of a Code in the Polymerization of Amino Acids along RNA Templates

Jean Lehmann1*, Michel Cibils2, Albert Libchaber1

1 Center for Studies in Physics and Biology, The Rockefeller University, New York, New York, United States of America, 2 Section de Mathématiques, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland

Abstract Top

The origin of the genetic code in the context of an RNA world is a major problem in the field of biophysical chemistry. In this paper, we describe how the polymerization of amino acids along RNA templates can be affected by the properties of both molecules. Considering a system without enzymes, in which the tRNAs (the translation adaptors) are not loaded selectively with amino acids, we show that an elementary translation governed by a Michaelis-Menten type of kinetics can follow different polymerization regimes: random polymerization, homopolymerization and coded polymerization. The regime under which the system is running is set by the relative concentrations of the amino acids and the kinetic constants involved. We point out that the coding regime can naturally occur under prebiotic conditions. It generates partially coded proteins through a mechanism which is remarkably robust against non-specific interactions (mismatches) between the adaptors and the RNA template. Features of the genetic code support the existence of this early translation system.

Citation: Lehmann J, Cibils M, Libchaber A (2009) Emergence of a Code in the Polymerization of Amino Acids along RNA Templates. PLoS ONE 4(6): e5773. doi:10.1371/journal.pone.0005773

Editor: Jörg Langowski, German Cancer Research Center, Germany

Received: March 10, 2009; Accepted: May 5, 2009; Published: June 3, 2009

Copyright: © 2009 Lehmann et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Funding: The authors have no support or funding to report.

Competing interests: The authors have declared that no competing interests exist.

* E-mail:



See another view/Vide outra opinião: Biologic Institute

Dominando a complexidade

Taming Complexity
Friday/Saturday 23/24 April 2010

Successful theories of the natural world are characterized by their elegance and simplicity. Yet much of what we see around us is messy and complex. Many theorists today believe that this complexity can be tamed, and that what will emerge are theoretical structures with the elegance that we have come to expect from studies of simpler systems. This effort involves a search for prototypical examples of complex systems—from liquid water to window glass to a pile of sand—and a blending of traditional mathematical methods with new ideas about how to exploit the great potential of modern computers to simulate these systems. Open questions range from interplay between complexity and quantum mechanics to the possibility that our models of complex systems can themselves be viewed as random mathematical objects. The theoretical exploration of complex systems continues to generate some of the most dramatic examples of how the same mathematical ideas can cut across classically distinct disciplines.

Speakers will include:

Roberto Car, Princeton University 

David Ceperley, University of Illinois 

Susan Coppersmith, University of Wisconsin 

Leticia Cugliandolo, Université Pierre et Marie Curie—Paris VI

Geoffrey E. Hinton, University of Toronto

Hernan Makse, City College of New York 

Jorge Kurchan, Ecole Supérieure de Physique et de Chimie Industrielles 

Frans Pretorius, Princeton University 

David Reichman, Columbia University 

James Sethna, Cornell University

If you are interested in attending the workshop, please email Funds are available to help students and postdocs stay in New York so they can participate more fully. A detailed schedule will be available shortly.


Você ouviu falar de complexidade irredutível de sistemas bióticos onde? E de informação complexa especificada? Foi na teoria do Design Inteligente, certo? Mas você ouviu falar também que a TDI é pseudociência e criacionismo disfarçado em um smokin barato, não foi mesmo? E o que este grupo de cientistas irá discutir 'cheira' às proposições teóricas do design inteligente? Cheira, não é mesmo? 

E ainda dizem que a teoria do Design Inteligente impede o avanço da ciência...

Física teórica e o fenômeno da vida

Theoretical physics and the phenomena of life
Friday/Saturday 19/20 March 2010

Nearly four hundred years ago, Galileo offered us the poetic image of the Book of Nature, lying open before us. We could read it, he said, if only we understood its language—the language of mathematics. This image motivates the search for a concise mathematical description of the world around us, and this intellectual adventure has been remarkably successful. From deep inside the atomic nucleus to the large scale structure of the universe, we can calculate what we see as we look quantitatively at the world. Beyond predictions about the natural world, this theoretical framework gives us the power to design new devices that have changed our lives in fundamental ways. But there is a chapter missing from our reading of the Book of Nature—the chapter about our inner world, about the phenomena of life. While experiments have uncovered many of the intricate mechanisms at work in the machinery of life, there is no predictive theoretical framework that ties these discoveries together, nothing comparable to the success of theoretical physics in organizing and codifying our understanding of the inanimate world. For many reasons, the time seems right to bridge this gap, to bring the rich and beautiful phenomena of life under this powerful predictive umbrella. This interaction between the physical and biological sciences has the potential to redraw the intellectual landscape of the sciences, and to change our view of ourselves.

Speakers will include:

Curtis Callan, Princeton University 

Adrienne Fairhall, University of Washington 

Irene Giardina, Università di Roma, La Sapienza 

Marilyn Gunner, City College of New York 

Philip Nelson, University of Pennsylvania 

Marcelo Magnasco, Rockefeller University 

José Nelson Onuchic, University of California at San Diego 

Boris Shraiman, University of California at Santa Barbara 

Massimo Vergassola, Institut Pasteur

If you are interested in attending the workshop, please email Funds are available to help students and postdocs stay in New York so they can participate more fully. A detailed schedule will be available shortly.



Mas Darwin não tinha explicado a origem e evolução das espécies através da seleção natural? O fato, Fato, FATO da evolução não é tão cientificamente comprovado como a lei da gravidade? E o que fazem esses físicos teóricos? Ah, eles não entendem nada de ciência, e nem como se dá a evolução. Devem ser religiosamente motivados para realizarem este workshop.

Fui, nem sei por que, pensando que cada vez mais confio nos físicos e químicos quanto a explicarem a origem e a evolução da vida do que nos biólogos.

Quanto de espaço sequencial de proteína foi explorado pela vida na Terra?

How much of protein sequence space has been explored by life on Earth?

David T.F Dryden*, Andrew R Thomson and John H White

-Author Affiliations
School of Chemistry, University of Edinburgh The King's Buildings, Edinburgh EH9 3JJ, UK
Author for correspondence (


We suggest that the vastness of protein sequence space is actually completely explorable during the populating of the Earth by life by considering upper and lower limits for the number of organisms, genome size, mutation rate and the number of functionally distinct classes of amino acids. We conclude that rather than life having explored only an infinitesimally small part of sequence space in the last 4 Gyr, it is instead quite plausible for all of functional protein sequence space to have been explored and that furthermore, at the molecular level, there is no role for contingency.

protein sequence    evolution    contingency


Received February 27, 2008.
Accepted March 25, 2008.

This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Copyright © 2008 The Royal Society


See another view here/Vide outra opinião aqui: Biologic Institute

NASA e o aquecimento global

"Each year, scientists at NASA’S Goddard Institute for Space Studies analyze global temperature data. The past year, 2009, tied as the second warmest year since global instrumental temperature records began 130 years ago. Worldwide, the mean temperature was 0.57°C (1.03°F) warmer than the 1951-1980 base period. And January 2000 to December 2009 came out as the warmest decade on record."

Crocopato: não é piada de mau gosto, é arte evolutiva diante de nossos olhos

Gente, e eu não consegui isso no blog Humor darwinista, mas no Dispersal of Darwin remetendo ao Brooklin Art Project.

"A evolução é mais inteligente do que você , idiota! (assim disse um dos papas da evolução cujo nome me fugiu agora). Adenda em 28/02/2010: É a conhecida Segunda Lei de Leslie Orgel (1927–2007)

Eletrônica inspirada na célula humana: a 'ilusão' de design inteligente para uma solução prática

sábado, fevereiro 27, 2010

Cell-inspired electronics

February 25, 2010 by Anne Trafton

Graphic: Christine Daniloff

( -- A single cell in the human body is approximately 10,000 times more energy-efficient than any nanoscale digital transistor, the fundamental building block of electronic chips. In one second, a cell performs about 10 million energy-consuming chemical reactions, which altogether require about one picowatt (one millionth millionth of a watt) of power.


MIT's Rahul Sarpeshkar is now applying architectural principles from these ultra-energy-efficient cells to the design of low-power, highly parallel, hybrid analog-digital electronic circuits. Such circuits could one day be used to create ultra-fast supercomputers that predict complex cell responses to drugs. They may also help researchers to design synthetic genetic circuits in cells.

In his new book, Ultra Low Power Bioelectronics (Cambridge University Press, 2010), Sarpeshkar outlines the deep underlying similarities between chemical reactions that occur in a cell and the flow of current through an analog electronic circuit. He discusses how biological cells perform reliable computation with unreliable components and noise (which refers to random variations in signals — whether electronic or genetic). Circuits built with similar design principles in the future can be made robust to electronic noise and unreliable electronic components while remaining highly energy efficient. Promising applications include image processors in cell phones or brain implants for the blind.

"Circuits are a language for representing and trying to understand almost anything, whether it be networks in biology or cars," says Sarpeshkar, an associate professor of electrical engineering and computer science. "There's a unified way of looking at the biological world through circuits that is very powerful."

Circuit designers already know hundreds of strategies to run analog circuits at low power, amplify signals, and reduce noise, which have helped them design low-power electronics such as mobile phones, mp3 players and laptop computers.

"Here's a field that has devoted 50 years to studying the design of complex systems," says Sarpeshkar, referring to electrical engineering. "We can now start to think of biology in the same way." He hopes that physicists, engineers, biologists and biological engineers will work together to pioneer this new field, which he has dubbed "cytomorphic" (cell-inspired or cell-transforming) electronics.


Read more here/Leia mais aqui: PhysOrg



Dizem os críticos e oponentes do Design Inteligente que o design que vemos e detectamos na natureza não é real, é ILUSÃO, e que as proposições teóricas do DI impedem o avanço da ciência. Ué, os caras estão aqui há 50 anos trabalhando com ideias de design inteligente antes da teoria do Design Inteligente??? São os nossos precursores? E nós do DI não sabíamos???

Talvez as intuições que nos capacitam reconhecer design magnífico como este deveriam estar presente nas mentes brilhantes dos cientistas quando tentarem explicá-lo como ilusão, produto do mero acaso e da fortuita necessidade. Não fazer isso, é sufocar a verdade evidente encontrada nas evidências em nome de um naturalismo filosófico que passa como se fosse ciência, e que é uma postura anticientífica.

Quem impede o avanço da ciência, cara-pálida?

Memorando de físicos britânicos sobre o Climategate: falta de integridade e de ciência

Memorandum submitted by the Institute of Physics (CRU 39)

The disclosure of climate data from the Climatic Research Unit at the University of East Anglia

The Institute of Physics is a scientific charity devoted to increasing the practice, understanding and application of physics. It has a worldwide membership of over 36,000 and is a leading communicator of physics-related science to all audiences, from specialists through to government and the general public. Its publishing company, IOP Publishing, is a world leader in scientific publishing and the electronic dissemination of physics.

The Institute is pleased to submit its views to inform the House of Commons Science and Technology Committee's inquiry, 'The disclosure of climate data from the Climatic Research Unit at the University of East Anglia'.

The submission details our response to the questions listed in the call for evidence, which was prepared with input from the Institute's Science Board, and its Energy Sub-group.

What are the implications of the disclosures for the integrity of scientific research?

1. The Institute is concerned that, unless the disclosed e-mails are proved to be forgeries or adaptations, worrying implications arise for the integrity of scientific research in this field and for the credibility of the scientific method as practised in this context.

2. The CRU e-mails as published on the internet provide prima facie evidence of determined and co-ordinated refusals to comply with honourable scientific traditions and freedom of information law. The principle that scientists should be willing to expose their ideas and results to independent testing and replication by others, which requires the open exchange of data, procedures and materials, is vital. The lack of compliance has been confirmed by the findings of the Information Commissioner. This extends well beyond the CRU itself - most of the e-mails were exchanged with researchers in a number of other international institutions who are also involved in the formulation of the IPCC's conclusions on climate change.

3. It is important to recognise that there are two completely different categories of data set that are involved in the CRU e-mail exchanges:

· those compiled from direct instrumental measurements of land and ocean surface temperatures such as the CRU, GISS and NOAA data sets; and

· historic temperature reconstructions from measurements of 'proxies', for example, tree-rings.

4. The second category relating to proxy reconstructions are the basis for the conclusion that 20th century warming is unprecedented. Published reconstructions may represent only a part of the raw data available and may be sensitive to the choices made and the statistical techniques used. Different choices, omissions or statistical processes may lead to different conclusions. This possibility was evidently the reason behind some of the (rejected) requests for further information.

5. The e-mails reveal doubts as to the reliability of some of the reconstructions and raise questions as to the way in which they have been represented; for example, the apparent suppression, in graphics widely used by the IPCC, of proxy results for recent decades that do not agree with contemporary instrumental temperature measurements.

6. There is also reason for concern at the intolerance to challenge displayed in the e-mails. This impedes the process of scientific 'self correction', which is vital to the integrity of the scientific process as a whole, and not just to the research itself. In that context, those CRU e-mails relating to the peer-review process suggest a need for a review of its adequacy and objectivity as practised in this field and its potential vulnerability to bias or manipulation.

7. Fundamentally, we consider it should be inappropriate for the verification of the integrity of the scientific process to depend on appeals to Freedom of Information legislation. Nevertheless, the right to such appeals has been shown to be necessary. The e-mails illustrate the possibility of networks of like-minded researchers effectively excluding newcomers. Requiring data to be electronically accessible to all, at the time of publication, would remove this possibility.

8. As a step towards restoring confidence in the scientific process and to provide greater transparency in future, the editorial boards of scientific journals should work towards setting down requirements for open electronic data archiving by authors, to coincide with publication. Expert input (from journal boards) would be needed to determine the category of data that would be archived. Much 'raw' data requires calibration and processing through interpretive codes at various levels.

9. Where the nature of the study precludes direct replication by experiment, as in the case of time-dependent field measurements, it is important that the requirements include access to all the original raw data and its provenance, together with the criteria used for, and effects of, any subsequent selections, omissions or adjustments. The details of any statistical procedures, necessary for the independent testing and replication, should also be included. In parallel, consideration should be given to the requirements for minimum disclosure in relation to computer modelling.

Are the terms of reference and scope of the Independent Review announced on 3 December 2009 by UEA adequate?

10. The scope of the UEA review is, not inappropriately, restricted to the allegations of scientific malpractice and evasion of the Freedom of Information Act at the CRU. However, most of the e-mails were exchanged with researchers in a number of other leading institutions involved in the formulation of the IPCC's conclusions on climate change. In so far as those scientists were complicit in the alleged scientific malpractices, there is need for a wider inquiry into the integrity of the scientific process in this field.

11. The first of the review's terms of reference is limited to: "...manipulation or suppression of data which is at odds with acceptable scientific practice..." The term 'acceptable' is not defined and might better be replaced with 'objective'.

12. The second of the review's terms of reference should extend beyond reviewing the CRU's policies and practices to whether these have been breached by individuals, particularly in respect of other kinds of departure from objective scientific practice, for example, manipulation of the publication and peer review system or allowing pre-formed conclusions to override scientific objectivity.

How independent are the other two international data sets?

13. Published data sets are compiled from a range of sources and are subject to processing and adjustments of various kinds. Differences in judgements and methodologies used in such processing may result in different final data sets even if they are based on the same raw data. Apart from any communality of sources, account must be taken of differences in processing between the published data sets and any data sets on which they draw.
The Institute of Physics

February 2010

Source/Fonte: Parliament UK

Por que Dawkins vai 'censurar' os comentários dos neoateus em seu blog?

Gente, eu nem pude acreditar no que li. Dawkins, o maior profeta ateu e de Darwin que toda a humanidade já teve, um racionalista que sempre teve a maior consideração pela razão e contra a censura de ideias, não resistiu à Galera de neoateus que, como a Galera dos meninos e meninas de Darwin, é mal-educada desde o berço. Triste conclusão: Dawkins vai 'censurar' os comentários dos neoateus brights, crèm de la crèm de la rationalité. 

Eu, fui mais inteligente do que o Dawkins. Segui o exemplo de outro ateu evolucionista, John Hawks, que não permite comentários no seu blog. Razão? Esta Galera é mal-educada, e não é capaz de debater civilmente. Além da covardia de se esconderem atrás de pseudônimos e contas de e-mails gratuitas. Entre o censurar comentários mais sujos do que privadas públicas-- pura perda de tempo, eu preferi não permitir comentários neste blog. Direito meu, e quem quiser que se estrebuche de raiva!


From The Times

February 26, 2010

Outraged atheists lose faith in Dawkins as he censors website

Hannah Devlin and Ruth Gledhill

Richard Dawkins is accustomed to provoking the wrath of religious communities, but now a schism seems to have opened up within the atheist community who make up his fan-base.

The split occurred after he announced that a discussion section on his website, considered one of the busiest online atheist forums, would in future be tightly moderated and “irrelevant postings and frivolous gossip” would no longer be allowed.

The change was scheduled for next month but such was the torrent of abuse after the announcement that the forum had to be locked down, deepening the rift between Professor Dawkins and his 85,000 online fans.

Writing on yesterday, in a posting entitled “Outrage”, he said that there was “something rotten” in internet culture and pledged to rid his website of its abusive element.

“Imagine seeing your face described by an anonymous poster, as ‘a slack-jawed turd-in-the-mouth mug’,” he wrote. “Surely there has to be something wrong with people who can resort to such over-the-top language, overreacting so spectacularly to something so trivial.

“Even some of those with more temperate language are responding to the proposed changes in a way that is little short of hysterical.”

Read more here/Leia mais aqui: Times Online

Purim Sameach 2010/5770

27-28 de fevereiro, 2010 – 14-15 de Adar (2) / 5770



Significado: Rememora a derrota de um plano para exterminar o povo judeu na antiga Pérsia.

Observância: Leitura pública do livro de Ester 'omitindo-se' o nome do vilão quase genocida.

Em 474 a. da e. C. lá na antiga Pérsia um vilão quase genocida quis aniquilar o povo de Israel. Em 2010 e. C., um líder político do Irã (antiga Pérsia) deseja o "Holocausto atômico" do povo judeu.

No primeiro Purim, o vilão foi enforcado,  e os judeus tiveram que lutar por suas vidas. E no Purim de 2010?

Princeton University visita este blog

sexta-feira, fevereiro 26, 2010

Eu tinha prometido a mim mesmo que, quando um visitante da Princeton University surgisse no meu relatório de visitantes, eu iria celebrar blogando a respeito. Razão? Eu queria ter feito um mestrado lá na Princeton University. Não pude, mas fico feliz de que este blog é consultado até lá! É ruim, hein?

Fonte: Sitemeter

Interações entre as espécies: poderosa força diretriz por detrás da evolução?

Interactions Between Species: Powerful Driving Force Behind Evolution?

ScienceDaily (Feb. 25, 2010) — Scientists at the University of Liverpool have provided the first experimental evidence that shows that evolution is driven most powerfully by interactions between species, rather than adaptation to the environment.

Computer rendering of virus particles. In a new study, researchers used fast-evolving viruses to observe hundreds of generations of evolution. They found that for every viral strategy of attack, the bacteria would adapt to defend itself, which triggered an endless cycle of co-evolutionary change. (Credit: iStockphoto/Martin McCarthy)

The team observed viruses as they evolved over hundreds of generations to infect bacteria. They found that when the bacteria could evolve defences, the viruses evolved at a quicker rate and generated greater diversity, compared to situations where the bacteria were unable to adapt to the viral infection.

The study shows, for the first time, that the American evolutionary biologist Leigh Van Valen was correct in his 'Red Queen Hypothesis'. The theory, first put forward in the 1970s, was named after a passage in Lewis Carroll's Through the Looking Glass in which the Red Queen tells Alice, 'It takes all the running you can do to keep in the same place'. This suggested that species were in a constant race for survival and have to continue to evolve new ways of defending themselves throughout time.

Dr Steve Paterson, from the University's School of Biosciences, explains: "Historically, it was assumed that most evolution was driven by a need to adapt to the environment or habitat. The Red Queen Hypothesis challenged this by pointing out that actually most natural selection will arise from co-evolutionary interactions with other species, not from interactions with the environment.

Read more here/Leia mais aqui: Science Daily



Nature advance online publication 24 February 2010 | doi:10.1038/nature08798; Received 8 September 2009; Accepted 23 December 2009; Published online 24 February 2010

Antagonistic coevolution accelerates molecular evolution

Steve Paterson1,5, Tom Vogwill1,5, Angus Buckling2, Rebecca Benmayor2, Andrew J. Spiers3, Nicholas R. Thomson4, Mike Quail4, Frances Smith4, Danielle Walker4, Ben Libberton1, Andrew Fenton1, Neil Hall1 & Michael A. Brockhurst1,5

1. School of Biological Sciences, Biosciences Building, University of Liverpool, Crown Street, Liverpool L69 7ZB, UK

2. Zoology Department, University of Oxford, South Parks Road, Oxford OX1 3PS, UK

3. SIMBIOS Centre, Level 5 Kydd Building, University of Abertay Dundee, Bell Street, Dundee DD1 1HG, UK

4. Pathogen Genomics, The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge CB10 1SA, UK

5. These authors contributed equally to this work.

Correspondence to: Michael A. Brockhurst1,5 Correspondence and requests for materials should be addressed to M.A.B. (Email:


The Red Queen hypothesis proposes that coevolution of interacting species (such as hosts and parasites) should drive molecular evolution through continual natural selection for adaptation and counter-adaptation1, 2, 3. Although the divergence observed at some host-resistance4, 5, 6 and parasite-infectivity7,8, 9 genes is consistent with this, the long time periods typically required to study coevolution have so far prevented any direct empirical test. Here we show, using experimental populations of the bacterium Pseudomonas fluorescens SBW25 and its viral parasite, phage Φ2 (refs 10, 11), that the rate of molecular evolution in the phage was far higher when both bacterium and phage coevolved with each other than when phage evolved against a constant host genotype. Coevolution also resulted in far greater genetic divergence between replicate populations, which was correlated with the range of hosts that coevolved phage were able to infect. Consistent with this, the most rapidly evolving phage genes under coevolution were those involved in host infection. These results demonstrate, at both the genomic and phenotypic level, that antagonistic coevolution is a cause of rapid and divergent evolution, and is likely to be a major driver of evolutionary change within species.


Professores, pesquisadores e alunos de universidades públicas e privadas com acesso ao site CAPES/Periódicos podem ler gratuitamente este artigo da Nature e de mais 22.440 publicações científicas.

Magnetômetro 'natural' na parte superior do bico de aves?

Natural 'Magnetometer' in Upper Beak of Birds?

ScienceDaily (Feb. 26, 2010) — Iron containing short nerve branches in the upper beak of birds may serve as a magnetometer to measure the vector of the Earth magnetic field (intensity and inclination) and not only as a magnetic compass, which shows the direction of the magnetic field lines. Several years ago, the Frankfurt neurobiologists Dr. Gerta Fleissner and her husband Prof. Dr. Günther Fleissner discovered these structures in homing pigeons and have, in close cooperation with the experimental physicist Dr. Gerald Falkenberg (DESY Hamburg), characterized the essential iron oxides.

Homing pigeon. (Credit: iStockphoto/Andrzej Podulka)

"After we had shown the system of dendrites with distinct subcellular iron-containing compartments in homing pigeons, immediately the question was posed whether similar dendritic systems may be found in other bird species, too," as Gerta Fleissner, the principal investigator, comments. Meanwhile they could describe similar candidate structures in the beaks of various avian species. X-Ray-fluorescence measurements at DESY demonstrated that the iron oxides within these nervous dendrites are identical. These findings were published few days ago in the high-ranking interdisciplinary online journal Plos One.

More than about 500 dendrites in the periphery encode the magnetic field information, which is composed in the central nervous system to a magnetic map. It obviously does not matter, whether birds use this magnetic map for their long distance orientation or do not -- the equipment can be found in migratory birds, like robin and garden warbler, and well as in domestic chicken. "This finding is astonishing, as the birds studied have a different life styles and must fulfil diverse orientational tasks: Homing pigeons, trained to return from different release sites to their homeloft, short-distance migrants like robins, long-distance migratory birds like garden warblers and also extreme residents like domestic chicken," explains Gerta Fleissner.

Read more here/Leia mais aqui: Science Daily


Avian Magnetoreception: Elaborate Iron Mineral Containing Dendrites in the Upper Beak Seem to Be a Common Feature of Birds

Gerald Falkenberg1, Gerta Fleissner2*, Kirsten Schuchardt2,Markus Kuehbacher3, Peter Thalau2, Henrik Mouritsen4,Dominik Heyers4, Gerd Wellenreuther1, Guenther Fleissner2

1 Hamburger Synchrotronstrahlungslabor HASYLAB at Deutsches Elektronen-Synchrotron (DESY), Hamburg, Germany, 2 Institut für Zellbiologie und Neurowissenschaften, Goethe-Universität, Frankfurt a. M., Germany, 3 Abt. Elementanalytik, Helmholtz Centre Berlin for Materials and Energy, Berlin, Germany, 4 Institut für Biologie und Umweltwissenschaften, Carl von Ossietzky-Universität, Oldenburg, Germany

Abstract Top

The magnetic field sensors enabling birds to extract orientational information from the Earth's magnetic field have remained enigmatic. Our previously published results from homing pigeons have made us suggest that the iron containing sensory dendrites in the inner dermal lining of the upper beak are a candidate structure for such an avian magnetometer system. Here we show that similar structures occur in two species of migratory birds (garden warbler, Sylvia borin and European robin, Erithacus rubecula) and a non-migratory bird, the domestic chicken (Gallus gallus). In all these bird species, histological data have revealed dendrites of similar shape and size, all containing iron minerals within distinct subcellular compartments of nervous terminals of the median branch of the Nervus ophthalmicus. We also used microscopic X-ray absorption spectroscopy analyses to identify the involved iron minerals to be almost completely Fe III-oxides. Magnetite (Fe II/III) may also occur in these structures, but not as a major Fe constituent. Our data suggest that this complex dendritic system in the beak is a common feature of birds, and that it may form an essential sensory basis for the evolution of at least certain types of magnetic field guided behavior.

Citation: Falkenberg G, Fleissner G, Schuchardt K, Kuehbacher M, Thalau P, et al. (2010) Avian Magnetoreception: Elaborate Iron Mineral Containing Dendrites in the Upper Beak Seem to Be a Common Feature of Birds. PLoS ONE 5(2): e9231. doi:10.1371/journal.pone.0009231

Editor: Eric Warrant, Lund University, Sweden

Received: August 13, 2009; Accepted: January 25, 2010; Published: February 16, 2010

Copyright: © 2010 Falkenberg et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Funding: The project is supported by grants from the Deutsche Forschungsgemeinschaft (Fl 177/15-1 and 16-1),; from HASYLAB at DESY, Hamburg (I-05-095, II-20060167),; from the Stiftung Polytechnische Gesellschaft, Frankfurt a. M.,; from the Gemeinnützige Hertie-Stiftung, Berlin: ZEN-program,; from the Alumni of the Goethe-University, Frankfurt a. M.,; from the Volkswagenstiftung (Heisenberg-Professorship to H.M.), The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Competing interests: The authors have declared that no competing interests exist.

* E-mail:


Patas de animais carnívoros: mero acaso, fortuita necessidade, ou design inteligente?

The Bigger the Animal, the Stiffer the 'Shoes': Carnivores' Feet 'Tuned' to Their Body Size

ScienceDaily (Feb. 25, 2010) — If a Tiger's feet were built the same way as a mongoose's feet, they'd have to be about the size of a hippo's feet to support the big cat's weight. But they're not.

A big dog's weight is borne by the big pad behind the toes. The bigger the animal, the stiffer the pad. (Credit: HTO, Wikimedia Commons)

For decades, researchers have been looking at how different-sized legs and feet are put together across the four-legged animal kingdom, but until now they overlooked the "shoes," those soft pads on the bottom of the foot that bear the brunt of the animal's walking and running.

New research from scientists in Taiwan and at Duke University has found that the mechanical properties of the pads vary in predictable fashion as animals get larger. In short, bigger critters need stiffer shoes.

Kai-Jung Chi, an assistant professor of physics at National Chung Hsing University in Taiwan ran a series of carefully calibrated "compressive tests" on the footpads of carnivores that have that extra toe halfway up the foreleg, including dogs, wolves, domestic cats, leopards and hyenas. She was measuring the relative stiffness of the pads across species -- how much they deformed under a given amount of compression.

"People hadn't looked at pads," said co-author V. Louise Roth, an associate professor of biology and evolutionary anthropology who was Chi's thesis adviser at Duke. "They've been looking at the bones and muscles, but not that soft tissue."

Read more here/Leia mais aqui: Science Daily


Scaling and mechanics of carnivoran footpads reveal the principles of footpad design

Kai-Jung Chi1,2,* and V. Louise Roth1

-Author Affiliations

1Biology Department, Duke University, Durham, NC 27708-0338, USA

2Department of Physics and Institute of Biophysics, National Chung Hsing University, Taichung 40227, Taiwan, Republic of China

*Author for correspondence (


In most mammals, footpads are what first strike ground with each stride. Their mechanical properties therefore inevitably affect functioning of the legs; yet interspecific studies of the scaling of locomotor mechanics have all but neglected the feet and their soft tissues. Here we determine how contact area and stiffness of footpads in digitigrade carnivorans scale with body mass in order to show how footpads’ mechanical properties and size covary to maintain their functional integrity. As body mass increases across several orders of magnitude, we find the following: (i) foot contact area does not keep pace with increasing body mass; therefore pressure increases, placing footpad tissue of larger animals potentially at greater risk of damage; (ii) but stiffness of the pads also increases, so the tissues of larger animals must experience less strain; and (iii) total energy stored in hindpads increases slightly more than that in the forepads, allowing additional elastic energy to be returned for greater propulsive efficiency. Moreover, pad stiffness appears to be tuned across the size range to maintain loading regimes in the limbs that are favourable for long-bone remodelling. Thus, the structural properties of footpads, unlike other biological support-structures, scale interspecifically through changes in both geometry and material properties, rather than geometric proportions alone, and do so with consequences for both maintenance and operation of other components of the locomotor system.

allometry    biomechanics   digitigrade mammals     feet     footpad function   locomotion


Received December 18, 2009.
Accepted February 1, 2010.
© 2010 The Royal Society



Primeira evidência de locomoção na biota de Ediacara da Formação Mistaken Point de 565 Milhões de anos

First evidence for locomotion in the Ediacara biota from the 565 Ma Mistaken Point Formation, Newfoundland

Alexander G. Liu1, Duncan Mcllroy2 and Martin D. Brasier1,2

-Author Affiliations

1Department of Earth Sciences, University of Oxford, Parks Road, Oxford OX1 3PR, UK

2Department of Earth Sciences, Memorial University of Newfoundland, St. John's, Newfoundland A1B 3X5, Canada


Evidence for locomotion in the Precambrian fossil record is scant. Reliable Ediacaran trace fossils are all younger than 560 Ma, and consist of relatively simple horizontal burrows and trails from shallow-water deposits. Here we describe an assemblage of macroscopic locomotory traces from deep-water environments at Mistaken Point, southeastern Newfoundland, Canada, dated to ca. 565 Ma. These trails extend the record of complex trace fossils back into the earliest Avalonian biota. Our new evidence for large motile organisms on the seafloor at this time suggests that at least some of these early Ediacaran organisms, whose biological affinities are widely debated, could have been muscular and of metazoan grade.

Received 7 May 2009.
Revision received 17 August 2009.
Accepted 18 August 2009.
© 2010 Geological Society of America


Requer assinatura do Geology, pois o site CAPES/Periódicos, lamentavelmente, não tem assinatura desta publicação científica.

Desenvolvimento e a evolução dos membro humanos

Development and the evolvability of human limbs

Nathan M. Young a,1, Günter P. Wagner b, and Benedikt Hallgrímsson c

-Author Affiliations

aDepartment of Orthopaedic Surgery, University of California, San Francisco, CA 94110;

bDepartment of Ecology and Evolutionary Biology, Yale University, New Haven, CT 06405; and

cDepartment of Cell Biology and Anatomy, University of Calgary, Calgary, AB, Canada T2N4N1

Edited* by David Pilbeam, Harvard University, Cambridge, MA, and approved December 29, 2009 (received for review October 14, 2009)


The long legs and short arms of humans are distinctive for a primate, the result of selection acting in opposite directions on each limb at different points in our evolutionary history. This mosaic pattern challenges our understanding of the relationship of development and evolvability because limbs are serially homologous and genetic correlations should act as a significant constraint on their independent evolution. Here we test a developmental model of limb covariation in anthropoid primates and demonstrate that both humans and apes exhibit significantly reduced integration between limbs when compared to quadrupedal monkeys. This result indicates that fossil hominins likely escaped constraints on independent limb variation via reductions to genetic pleiotropy in an ape-like last common ancestor (LCA). This critical change in integration among hominoids, which is reflected in macroevolutionary differences in the disparity between limb lengths, facilitated selection for modern human limb proportions and demonstrates how development helps shape evolutionary change.

bipedalism    hominin    integration   macroevolution   serial homology


1To whom correspondence should be addressed.

Author contributions: N.M.Y. designed research; N.M.Y. performed research; N.M.Y. and B.H. contributed new reagents/analytic tools; N.M.Y., G.W., and B.H. analyzed data; and N.M.Y., G.W., and B.H. wrote the paper.

↵*This Direct Submission article had a prearranged editor.

The authors declare no conflict of interest.

This article contains supporting information online at


PDF gratuito deste artigo aqui.

Será que este tipo de aula de Biologia ainda acontece no Brasil?

Será que uma aula de Biologia do 3º. ano do ensino médio ainda é assim no Brasil?

1) A evolução (seja lá o que isto signifique) é um fato, fato, FATO científico tão corroborado como a lei da gravidade.

2) O debate sobre a evolução acabou e a ciência já decidiu: Darwin foi o homem que colocou o ser humano no seu devido lugar - não somos diferentes das outras espécies.

3) “Nada em biologia faz sentido a não ser à luz da evolução”.

4) Todos os verdadeiros cientistas concordam que Darwin resolveu os mistérios da vida e que a variação randômica/mutação mais a seleção natural é a maior ideia que toda a humanidade já teve.

5) O registro fóssil simplesmente está transbordando de evidências do gradualismo darwiniano.

6) Não existe nenhuma crise epistêmica fundamental com a teoria da evolução através da seleção natural.

7) Se você questionar quaisquer uma dessas afirmações científicas acima, você só pode ser um fanático religioso fundamentalista estúpido que deseja somente destruir a ciência.

Se ainda ocorre, é lamentável, pois quando uma teoria científica não consegue explicar o que se propôs - no caso de Darwin - a origem e a evolução das espécies através da seleção natural, o que deveria ser ensinado em salas de aulas de ciência é que Darwin não fecha as contas epistêmicas desde 1859, e que os cientistas em vez de ficarem criando teorias ad hoc para livrar a cara de Darwin do fiasco em um contexto de justificação teórica, deveriam sim perguntar se a teoria dele está errada ou não. 

Em outras palavras, em vez de ficar engabelando os estudantes do ensino médio, e os leitores não especializados, eles deveriam abandonar a prática de tentar 'encaixar' as evidências inesperadas para corroborar a teoria original, quando essas evidências já podem ter solapado a suposta robustez epistêmica.

Fui, pensando, não sei por que, a ciência não pode andar de mãos dadas com a mentira, mas anda. Darwin que não me deixa mentir. Razão? Quando a questão é Darwin, a Nomenklatura científica é tutti cosa nostra, capice?

Ministro da Educação, Fernando Haddad, manda retirar a evolução química dos livros-textos aprovados pelo MEC/SEMTEC/PNLEM em 2010

quinta-feira, fevereiro 25, 2010

A sopa primordial já “está vencida bem além da data de validade”

por David Tyler 06:07:13 am

È bem conhecido que Darwin especulou sobre o que poderia acontecer em “algum pequeno lago quente” (discutido previamente aqui).

Mas só foi em 1929 que J.B.S. Haldane desenvolveu uma hipótese testável envolvendo um “ensopado prebiótico, ou a sopa primordial”. Ele propos que compostos orgânicos eram produzidos quando o metano, amônia e água reagiam como resultado da energia fornecida pela radiação ultravioleta. Os produtos da reação foram sugeridos como tendo se acumulado em uma “sopa quente diluída” na Terra primeva. Neste cenário, reações posteriores resultaram em macromoléculas, protocélulas e depois a vida.

“Apoiada pela síntese inorgânica de moléculas orgânicas de Stanley Miller's (1953) no laboratório, pareceu a gerações de cientistas que a narrativa de Haldane estava basicamente correta, e tudo o que foi deixado foi ordenar os detalhes."

Chegou a hora de prosseguir sem esta pesquisa improdutiva (fonte aqui

As experiências de Miller se tornaram um ícone da evolução naturalista, e entro nos livros-textos com muito pouca análise crítica das descobertas. Até recentemente, o trabalho de Miller foi aclamado na revista científica Science.

Felizmente, existem oportunidades de se ir além da ‘onda’, mas, como Jonathan Wells demonstrou no seu livro Icons of Evolution, estas contribuições raramente passam além da literature técnica. William Martin e colegas apresentaram um casoforte para se aposentar o conceito de sopa primordial da ativa. Ele já chegou à idade avançada de 81 anos e, como uma hipótese, ela não foi confirmada. Normalmente, quando as hipóteses são testadas e não são confirmadas, elas são descartadas — mas nós estamos agora com uma hipótese há muito vencida para isso acontecer com a sopa primordial. Ela já está “vencida bem além do seu prazo de validade.”

Duas razões foram fornecidas no artigo. A primeira é que a sopa de elementos químicos orgânicos estaria em equilíbrio termodinâmico. Os produtos da reação já estam presentes, e não há uma fonte de energia óbvia para conduzir a polimerização ou qualquer outra mudança significante. “A radiação ultra-violeta ionizante destroi inerentemente tanto quanto cria”.

“[T]he homogeneous soup has no internal free energy that would allow them to react further. Life is not just about replication; it is also a coupling of chemical reactions — exergonic ones that release energy and endergonic ones that utilise it, preventing the dissipation of energy as heat. It is commonplace to say that life requires energy, but the conception of a primordial soup fails to recognise or incorporate the importance of energy flux. On the congruence principle, what life needed was not some harsh and problematic source of energy like UV radiation (or lightning), but a continuous and replenishing source of chemical energy.”

“[A] sopa homogênea não tem energia interna livre que lhes permitisse reagir mais. A vida não é somente sobre replicação; também é da união de reações químicas — reações exergônicas que liberam energia e reações endergônicas que a utilizam, impedindo a dissipação de energia como calor. É banal dizer que a vida requer energia, mas a concepção de uma sopa primordial falha em reconhecer ou incorporar a importância do fluxo de energia. Baseado no princípio da congruência, o que a vida precisava não foi alguma fonte de energia severa e problemática como a radiação UV (ou raios), mas uma fonte de energia química contínua e reabastecedora.”

A segunda razão diz respeito à fermentação como o mecanismo primordial de geração de energia em um mundo sem oxigênio. Haldane promoveu esta ideia, e De Duve a apoiou como sendo o mecanismo para sustentar a vida anaeróbica. “Se isto pode ser dito como sendo a opinião de um livro-texto, é isso mesmo.”

“But there are profound difficulties — both chemical and biological — in viewing fermentation as primitive rather than derived. Fermentation is chemically a disproportionation — not a simple redox reaction, in which electrons are stripped from a donor and passed onto an acceptor, driven by strong thermodynamics. In contrast with respiration, the amount of energy released by fermentation is tiny, reflecting its lack of thermodynamic driving force. To tap such an insignificant source of energy requires more rather than less sophistication, and indeed about 12 enzymes are needed to catalyse a complex succession of steps in glycolytic-type fermentations based around the Embden-Meyerhoff pathway. These enzymes are proteins encoded by genes, which would have had to evolve as a functional unit without any other source of energy in the primordial oceans — close to an impossibility in an RNA world, let alone the only way to evolve one.”

“Mas há dificuldades profundas — tanto químicas como biológicas — em considerar a fermentação como sendo primitiva em vez de derivada. A fermentação é quimicamente uma desproporciação — não é uma reação redox, na qual os elétrons são tirados de um doador e passada adiante a um receptor, dirigida por forte termodinâmica. Em contraste com a respiração, a quantidade de energia liberada pela fermentação é pequeníssima, refletindo sua falta de força termodinâmica motriz. Para derivar tal fonte insignificante de energia exige mais do que menos sofisticação, e na verdade, cerca de 12 enzimas são necessárias para catalizar uma sucessão complexa de etapas em fermentações do tipo glicolítica baseadas em torno da via glicolítica ou via Embden-Meyerhoff. Estas enzimas são proteínas codificadas por genes, que teriam de ter evoluído como uma unidade functional sem qualquer outra fonte de energia nos oceanos primordiais — próximo de uma impossibilidade em um mundo RNA, muito menos a única maneira de evoluir um.”

Os autores prosseguem defendendo o ponto de vista deles de que a fermentação é uma derivação sofisticada, em vez de uma derivação primordial. Isto os leva à questão decisiva:

“But if there was no soup, and no energy from UV radiation or fermentation, then where was the energy that powered the emergence of life?”

“Mas, se não houve nenhuma sopa, e nenhuma energia da radiação UV ou de fermentação, então onde estava a energia que energizou a emergência da vida?”

Eles continuam o artigo propondo as fontes alcalinas hidrotermais como a fonte primordial de energia para a vida. Eles desenvolvem a ideia deles de que a origem da vida pode ser considerada distintamente da origem da replicação. Eles apoiam a proposta de Russell et al (1993) de que a quimiosmose é “uma propriedade inerente da vida, uma propriedade herdada do local e espaço onde ela surgiu”. O artigo deles é exploratório, não traçando quaisquer detalhes do que LUCA — Last Universal Common Ancestor (Último ancestral comum universal) teria parecido, mas considerando como que a quimiosmose poderia ter funcionado no ambiente das fontes alcalinas hidrotermais. Mais discussão disso se faz necessária, é claro, mas esta postagem é para chamar a atenção do desafio que estes autores apresentam aos pesquisadores da origem da vida geralmente e aos autores/educadores de livros-texto.

“It is time to cast off the shackles of fermentation in some primordial soup as ‘life without oxygen’ — an idea that dates back to a time before anybody had any understanding of how ATP is made - and to embrace the most revolutionary idea in biology since Darwin as the key not only to the bioenergetics of all life on Earth today, but to its very origin.(80) Thus it seems to us likely that LUCA grew on the H2/CO2 couple, and that she was naturally chemiosmotic.”

“Chegou a hora de se lançar fora os grilhões da fermentação em alguma sopa primordial como a ‘vida sem oxigênio’ — uma ideia que remonta a um tempo antes que alguém tivesse qualquer entendimento de como que o ATP é feito — e seguir a ideia mais revolucionária em biologia desde Darwin como a chave, não somente para a bioenergética de toda a vida na Terra, mas à sua própria origem.(80) Assim, parece para nós, provavelmente, que o LUCA cresceu devido ao casal H2/CO2, e que ela era naturalmente quimiosmótica.”

How did LUCA make a living? Chemiosmosis in the origin of life
Nick Lane, John F. Allen, William Martin
Bioessays, Published Online: Jan 27 2010 | DOI: 10.1002/bies.200900131

Despite thermodynamic, bioenergetic and phylogenetic failings, the 81-year-old concept of primordial soup remains central to mainstream thinking on the origin of life. But soup is homogeneous in pH and redox potential, and so has no capacity for energy coupling by chemiosmosis. Thermodynamic constraints make chemiosmosis strictly necessary for carbon and energy metabolism in all free-living chemotrophs, and presumably the first free-living cells too. Proton gradients form naturally at alkaline hydrothermal vents and are viewed as central to the origin of life. Here we consider how the earliest cells might have harnessed a geochemically created proton-motive force and then learned to make their own, a transition that was necessary for their escape from the vents. Synthesis of ATP by chemiosmosis today involves generation of an ion gradient by means of vectorial electron transfer from a donor to an acceptor. We argue that the first donor was hydrogen and the first acceptor CO2.

Vide também:

New Research Rejects 80-Year Theory of 'Primordial Soup' as the Origin of Life, ScienceDaily (3 February 2010)

Warren, D. Back to the beginning, The Ottawa Citizen (6 February 2010)

Transferência de energia eletrônica quanticamente coerente: a natureza pensou nisso primeiro?

Quantum-Coherent Electronic Energy Transfer: Did Nature Think of It First?

Gregory D. Scholes*

Department of Chemistry, Institute for Optical Sciences and Centre for Quantum Information and Quantum Control, University of Toronto, 80 St. George Street, Toronto, Ontario, M5S 3H6 Canada

J. Phys. Chem. Lett., 2010, 1 (1), pp 2–8
DOI: 10.1021/jz900062f

Publication Date (Web): January 7, 2010

Copyright © 2010 American Chemical Society



Recent research suggests that electronic energy transfer in complex biological and chemical systems can involve quantum coherence, even at ambient temperature conditions. It is particularly notable that this phenomenon has been found in some photosynthetic proteins. The role of these proteins in photosynthesis is introduced. The meaning of quantum-coherent energy transfer is explained, and it is compared to F€orster energy transfer. Broad, interdisciplinary questions for future work are noted. For example, how can chemists use quantum coherence in synthetic systems (perhaps in organic photovoltaics)? Why did certain  photosynthetic organisms evolve to use quantum coherence in light harvesting? Are these electronic excitations entangled?


Um novo sistema de determinação do sexo em um parente próximo do rato doméstico

African Pygmy Mice: Females Are XY ... Researchers Find out Why

ScienceDaily (Feb. 25, 2010) — In a great majority of cases, the Y chromosome determines sex in mammals. The African pygmy mouse M. minutoides is an exception to this rule. In this species, which is a close relative of the house mouse, it is the X chromosome that determines sex.

An XY female Mus minutoides. (Credit: Copyright Frédéric Veyrunes / CNRS 2009)

A team led by Frédéric Veyrunes, CNRS researcher at the Institut des Sciences de l'Evolution in Montpellier, working in collaboration with biologists from the Institut de Génomique Fonctionnelle in Lyon and the IRD, have just identified this unexpected case of sex determination. These scientists have demonstrated a particular chromosomal rearrangement on the X chromosome of this mouse. This work should provide a clearer understanding of how classic sex determination functions in mammals.

The research is published in the 7 April issue of the journal Proceedings of the Royal Society B.

In the great majority of mammals, sex determination follows a simple rule: an XX chromosome arrangement defines a female while an XY arrangement produces a male. However, some situations may deviate from this principle, in which case reference is made to chromosomal anomalies that most generally cause sterility. On the Y chromosome, sex is determined by the presence or absence of a single gene called Sry. Located in 1990, this gene initiates the development of male characteristics; without this gene, the gonads become ovaries.

However, some mammal species do not obey this rule. Until now, only seven cases of atypical sex determination had been observed, all in rodents. The team coordinated by Frédéric Veyrunes has just identified a new case, the first to be described for 30 years, in Mus minutoides, an African pygmy mouse species which is particularly interesting as it is very closely related to the house mouse, the principal mammal model used in biology. By studying different populations of African Mus minutoides, the researchers observed a very high proportion of fertile females carrying XY chromosomes (between 74% and 100%).
Read more here/Leia mais aqui: Science Daily


A novel sex determination system in a close relative of the house mouse

Frederic Veyrunes1,*, Pascale Chevret2, Josette Catalan1, Riccardo Castiglia3, Johan Watson4, Gauthier Dobigny5, Terence J. Robinson6 and Janice Britton-Davidian1

-Author Affiliations

1Institut des Sciences de l'Evolution (UMR CNRS/Université Montpellier II),Montpellier, France

2Institut de Génomique Fonctionnelle de Lyon (UMR CNRS/INRA/Université Lyon 1/ENS Lyon), Lyon, France

3Dipartimento di Biologia Animale e dell'Uomo, Università di Roma ‘La Sapienza’, Rome, Italy

4Free State Department of Economic Development, Tourism and Environmental Affairs, Bloemfontein, South Africa

5Institut de Recherche pour le Développement, Centre de Biologie pour la Gestion des Populations (UMR IRA/INRA/SupAgro/Cirad), Centre Régional Agrhymet BP11011, Niamey, Niger

6Evolutionary Genomics Group, Department of Botany and Zoology, University of Stellenbosch, Stellenbosch, South Africa
*Author for correspondence (


Therian mammals have an extremely conserved XX/XY sex determination system. A limited number of mammal species have, however, evolved to escape convention and present aberrant sex chromosome complements. In this study, we identified a new case of atypical sex determination in the African pygmy mouse Mus minutoides, a close evolutionary relative of the house mouse. The pygmy mouse is characterized by a very high proportion of XY females (74%, n = 27) from geographically widespread Southern and Eastern African populations. Sequencing of the high mobility group domain of the mammalian sex determining gene Sry, and karyological analyses using fluorescence in situ hybridization and G-banding data, suggest that the sex reversal is most probably not owing to a mutation of Sry, but rather to a chromosomal rearrangement on the X chromosome. In effect, two morphologically different X chromosomes were identified, one of which, designated X*, is invariably associated with sex-reversed females. The asterisk designates the still unknown mutation converting X*Y individuals into females. Although relatively still unexplored, such an atypical sex chromosome system offers a unique opportunity to unravel new genetic interactions involved in the initiation of sex determination in mammals.

African pygmy mouse    Mus minutoides     atypical sex determination system;   sex-reversed females
Sry gene   X* chromosome


Received October 21, 2009.
Accepted November 17, 2009.
© 2009 The Royal Society


Territórios cromossômicos

Chromosome Territories

Thomas Cremer1,2 and
Marion Cremer1

-Author Affiliations

1Biozentrum, Department of Biology II (Chair of Anthropology and Human Genetics), Ludwig-Maximilians-University, Grosshadernerstrasse 2, 82152 Martinsried, Germany

2Munich Center for Integrated Protein Sciences (CIPSM), 81377 Munich, Germany


Chromosome territories (CTs) constitute a major feature of nuclear architecture. In a brief statement, the possible contribution of nuclear architecture studies to the field of epigenomics is considered, followed by a historical account of the CT concept and the final compelling experimental evidence of a territorial organization of chromosomes in all eukaryotes studied to date. Present knowledge of nonrandom CT arrangements, of the internal CT architecture, and of structural interactions with other CTs is provided as well as the dynamics of CT arrangements during cell cycle and postmitotic terminal differentiation. The article concludes with a discussion of open questions and new experimental strategies to answer them.
Copyright © 2010 Cold Spring Harbor Laboratory Press; all rights reserved


Anatomia de parte mole de artrópodes bivalves Kunyangella e Kunmingella do Cambriano Inferior: significância para as relações filogenéticas dos Bradoriida

Soft-part anatomy of the Early Cambrian bivalved arthropodsKunyangella and Kunmingella: significance for the phylogenetic relationships of Bradoriida

Xianguang Hou1,*, Mark Williams2, David J. Siveter2, Derek J. Siveter3,4, Richard J. Aldridge2 and Robert S. Sansom2

-Author Affiliations

1Yunnan Key Laboratory for Palaeobiology, Yunnan University, Kunming 650091, Yunnan Province, People's Republic of China

2Department of Geology, University of Leicester, University Road, Leicester LE1 7RH, UK

3Geological Collections, University Museum of Natural History, Oxford OX1 3PW, UK

4Department of Earth Sciences, University of Oxford, Parks Road, Oxford OX1 3PR, UK

*Author for correspondence (


Bradoriids are small bivalved marine arthropods that are widespread in rocks of Cambrian to Early Ordovician age. They comprise seven families and about 70 genera based on shield (‘carapace’) morphology. New bradoriid specimens with preserved soft-part anatomy of Kunmingella douvillei(Kunmingellidae) are reported from the Early Cambrian Chengjiang Lagerstätte of China together with, for the first time to our knowledge, a second bradoriid species with preserved soft parts, Kunyangella cheni(Comptalutidae). Kunmingella douvillei has a 10-segmented limb-bearing body with uniramous ninth and tenth appendages and a series of homogeneous, apparently (proximal parts not preserved) unspecialized post-antennal biramous limbs with setose leaf-shaped exopods. Each endopod consists of five podomeres. A presumed penultimate instar of Ky. cheni preserves remnants of three head and two trunk appendages, and the adult is reconstructed as having four head appendages. This material allows testing of the affinity of the Bradoriida. Kunmingella is identified as a stem crustacean in character-based analyses, through both morphological comparisons and cladistic reconstructions. Global parsimony analysis recovers a monophyletic Bradoriida as the sister group to crown crustaceans.

Arthropoda  Bradoriida  Cambrian  Chengjiang Lagerstätte   China   exceptional preservation


Received December 1, 2009.
Accepted February 2, 2010.

© 2010 The Royal Society



Alguém sabe me dizer a quantas anda aquela pesquisa que encontrou resíduos de proteína em fóssil de T. rex? E o que isso agora significa? Partes moles em fósseis do Cambriano??? Cruz, credo... Valha-nos, São Darwin...

Erros em livros didáticos de ciências na Inglaterra e País de Gales

quarta-feira, fevereiro 24, 2010

An Analysis of Misconceptions in Science Textbooks: Earth science in England and Wales

Author: Chris John Henry King a


a Keele University, UK

DOI: 10.1080/09500690902721681
Published in: International Journal of Science Education, Volume 32, Issue 5 March 2010 , pages 565 - 601

First Published on: 27 May 2009

Subject: Science Education;

Previously published as: European Journal of Science Education (0140-5284) until 1987


Surveys of the earth science content of all secondary (high school) science textbooks and related publications used in England and Wales have revealed high levels of error/misconception. The 29 science textbooks or textbook series surveyed (51 texts in all) showed poor coverage of National Curriculum earth science and contained a mean level of one earth science error/misconception per page. Science syllabuses and examinations surveyed also showed errors/misconceptions. More than 500 instances of misconception were identified through the surveys. These were analysed for frequency, indicating that those areas of the earth science curriculum most prone to misconception are sedimentary processes/rocks, earthquakes/Earth's structure, and plate tectonics. For the 15 most frequent misconceptions, examples of quotes from the textbooks are given, together with the scientific consensus view, a discussion, and an example of a misconception of similar significance in another area of science. The misconceptions identified in the surveys are compared with those described in the literature. This indicates that the misconceptions found in college students and pre-service/practising science teachers are often also found in published materials, and therefore are likely to reinforce the misconceptions in teachers and their students. The analysis may also reflect the prevalence earth science misconceptions in the UK secondary (high school) science-teaching population. The analysis and discussion provide the opportunity for writers of secondary science materials to improve their work on earth science and to provide a platform for improved teaching and learning of earth science in the future. 

Keywords: Earth science education; High school; Misconception; Secondary school; Textbooks


Professores, pesquisadores e alunos de universidades públicas e privadas com acesso ao site CAPES/Periódicos podem ler gratuitamente este artigo do International Journal of Science Education e de mais 22.440 publicações científicas.


Exmo. Sr. Ministro da Educação:

Quando é que o MEC vai lidar seriamente com a questão de duas fraudes e de várias distorções de evidências científicas a favor do fato, Fato, FATO da evolução em nossos livros-texto de Biologia do ensino médio que são aprovados pelo MEC/SEMTEC/PNLEM?

Se na Inglaterra e no País de Gales a coisa está preta em termos de 171 acadêmico, imagina aqui nas tabas tupiniquins de Pindorama...

BEACON: US$ 25 milhões para detectar a ação da seleção natural diante de nossos olhos

Welcome to BEACON

The mission of the Bio/computational Evolution in Action CONsortium (BEACON) is to conduct research on fundamental evolutionary dynamics in both natural and artificial systems, educate a generation of multi-disciplinary scientists in these methods, and improve public understanding of evolution at all levels. The center will unite biologists who study natural evolutionary processes with computer scientists and engineers who are harnessing these processes to solve real-world problems. Developers of evolutionary algorithms have long borrowed high-level concepts from biology to improve problem-solving methods, but have not always captured the nuances of evolutionary theory. Likewise, studying the evolution of artificial systems can provide biologists with insight into the dynamics of the evolutionary process and the critical factors underlying emergent properties and behaviors. BEACON will promote the transfer of discoveries from biology into computer science and engineering design, while using novel computational methods and systems to address complex biological questions that are difficult or impossible to study with natural organisms.

As Dobzhansky famously noted, "Nothing in biology makes sense except in the light of evolution." BEACON's vision focuses that light, revealing fundamental biological concepts and illuminating the path toward computational applications. The key insight underlying the Center is that transformative discoveries in both computing and biology are possible through studying evolution as it happens, in both natural and digital domains. The philosopher Dennett (2002) has pointed out the algorithmic nature of evolution as a process that will occur in any system with "replication, variation (mutation) and differential fitness (competition)". BEACON aims to understand evolution in this universal framework.

The rationale for BEACON as a center is that a long-term and large-scale infrastructure is needed to draw together the scientists who, through research in their own disciplines, hold the interlocking keys to solving complex and fundamental problems in domains as diverse as cyber-security, epidemiology, and environmental sustainability. The center will promote cross-disciplinary experience to both new and established researchers, and stimulate multidisciplinary investigations. Historically, biologists and evolutionary computation developers have had minimal interactions. New research in digital evolution can act as a conceptual glue to join these fields and make evolutionary concepts more accessible to the public.

BEACON has assembled a multi-disciplinary team at Michigan State University (MSU), the University of Texas at Austin, the University of Washington, North Carolina A&T State University, and the University of Idaho. BEACON members include experts in the core fields of computer science and evolutionary biology, and allied areas across the natural sciences, engineering, mathematics, philosophy, and education. The team has established a strong record of multi-disciplinary and cross-institutional research, effective educational programs, and human resource diversity.

Thrust Groups

To facilitate the exchange of ideas, BEACON has three research thrust groups, each addressing a broad theme that cuts across computational and biological thinking, but at different hierarchical levels. The Evolution of Genomes, Networks, and Evolvabilitygroup will focus on mechanisms of genetic change, organization, encoding of information, and developmental processes. TheEvolution of Behavior and Intelligence group will emphasize evolution of phenotypic traits of self-directed organisms including complex behaviors and early forms of intelligence. The Evolution of Communities and Collective Dynamics group will investigate evolution in large groups of organisms, focusing on issues related to the evolution of group structure and societal development, as well as emergent properties of ecological communities. To promote the two-way flow of discoveries and concepts, each thrust group will include team leaders and researchers from both biological and computational fields. In one direction, this flow will facilitate critical advances in evolutionary methods and algorithms. In the other direction, the speed, precision, and repeatability of computational evolution will enable biologists to test complex hypotheses that are experimentally impractical in natural systems. Thus, the twin goalsof BEACON are (1) to develop and apply evolutionary principles of adaptation and resiliency in computer science and engineering design, and (2) to use computational systems in tandem with biological experiments to test complex biological hypotheses. The initial research projects are highly multidisciplinary and multi-institutional. BEACON will actively promote technology transfer of its findings to industry: the Center's Industrial Affiliates will include several companies, large and small, with which Center researchers have established or emerging collaborations.

Education and human resource development

Education and human resource development activities of BEACON include faculty and postdoc mentoring, novel curricula both at graduate and undergraduate levels, training programs for high-school and middle-school teachers, and an array of outreach programs to engage K-12 students and the general public. For example, graduate students at all partners will become proficient in both computational sciences and evolutionary biology; each will start with a bridge course covering the fundamentals in the complementary discipline, followed by a project course engaging teams of students and faculty from both disciplines in a hands-on project with evolution in action. This training format, previously developed by the PI to train biologists and engineers for joint work in ecological modeling, was enormously successful. A typical example of BEACON outreach is a training program for high-school science instructors in applying novel software-based tools to teach basic evolutionary principles. The software will provide selfreplicating programs that evolve the capacity to solve problems and puzzles. Students can explore and test evolutionary concepts in a game-like environment, giving them hands-on experience with principles that otherwise seem abstract. Versions of this software will be made available in museums and on the web.


BEACON investigators are unusually diverse. Student diversity will be assured by building on the highly successful Sloan Graduate Program at MSU, which has recruited many African American and Hispanic graduate students from HBCUs, including North Carolina A&T. Partnership with NC A&T will provide their graduates opportunities at Center partners that offer Ph.D degrees not available at NC A&T. Undergraduate research assistants, especially from underrepresented minorities, will be recruited under MSU's Professorial Assistant Program and REU supplements. BEACON will also draw upon and contribute to NSF's National Evolutionary Synthesis Center, NESCent, an organization with a related, but distinct, mission. The educational and computational tools developed by BEACON will be shared with NESCent, and NESCent programs will be tapped for use in BEACON's graduate and teacher training.


BEACON is a consortium of universities led by Michigan State University with partner institutions of North Carolina A&T State University, the University of Idaho, the University of Texas at Austin, and the University of Washington.

Biomecânica do pterossauro pteroide

Biomechanics of the unique pterosaur pteroid

Colin Palmer1,* and Gareth J. Dyke2

-Author Affiliations

1Department of Earth Sciences, University of Bristol, Queens Road, Bristol BS8 1RJ, UK

2School of Biology and Environmental Sciences, University College Dublin,Belfield, Dublin 4, Ireland

*Author for correspondence (


Pterosaurs, flying reptiles from the Mesozoic, had wing membranes that were supported by their arm bones and a super-elongate fourth finger. Associated with the wing, pterosaurs also possessed a unique wrist bone—the pteroid—that functioned to support the forward part of the membrane in front of the leading edge, the propatagium. Pteroid shape varies across pterosaurs and reconstructions of its orientation vary (projecting anteriorly to the wing leading edge or medially, lying alongside it) and imply differences in the way that pterosaurs controlled their wings. Here we show, using biomechanical analysis and considerations of aerodynamic efficiency of a representative ornithocheirid pterosaur, that an anteriorly orientated pteroid is highly unlikely. Unless these pterosaurs only flew steadily and had very low body masses, their pteroids would have been likely to break if orientated anteriorly; the degree of movement required for a forward orientation would have introduced extreme membrane strains and required impractical tensioning in the propatagium membrane. This result can be generalized for other pterodactyloid pterosaurs because the resultant geometry of an anteriorly orientated pteroid would have reduced the aerodynamic performance of all wings and required the same impractical properties in the propatagium membrane. We demonstrate quantitatively that the more traditional reconstruction of a medially orientated pteroid was much more stable both structurally and aerodynamically, reflecting likely life position.

flight     wing membrane    ornithocheirids    Coloborhynchus    Anhanguera    aerodynamics


Received October 17, 2009.
Accepted November 17, 2009.

© 2009 The Royal Society