Nenhuma distinção de ortologia/paralogia entre genes do grupo sanguíneo Rh de humanos e de chimpanzés

No distinction of orthology/paralogy between human and chimpanzee Rh blood group genes

Takashi Kitano1,*, Choong-Gon Kim1,#, Antoine Blancher2 and Naruya Saitou1

- Author Affiliations

1Division of Population Genetics, National Institute of Genetics, Mishima, Japan

2Laboratoire d’Immunogénétique Moléculaire (LIMT, EA3034), Faculté de Médecine Purpan, Université Paul Sabatier, Toulouse III, France

Author for Correspondence: Takashi Kitano, Department of Biomolecular Functional Engineering, College of Engineering, Ibaraki University, 4-12-1 Nakanarusawa-cho, Hitachi 316-8511, Japan, Tel: +81-294-38-5050, Fax: +81-294-38-5078, E-mail: tkitano@mx.ibaraki.ac.jp

Received April 20, 2015. Revision received November 13, 2015. Revision received January 16, 2016. Accepted February 8, 2016.

Abstract

On human (Homo sapiens) chromosome 1, there is a tandem duplication encompassing Rh blood group genes (Hosa_RHD and Hosa_RHCE). This duplication occurred in the common ancestor of humans, chimpanzees (Pan troglodytes), and gorillas, after splitting from their common ancestor with orangutans. Although several studies have been conducted on ape Rh blood group genes, the clear genome structures of the gene clusters remain unknown. Here, we determined the genome structure of the gene cluster of chimpanzee Rh genes by sequencing five BAC clones derived from chimpanzees. We characterized three complete loci (Patr_RHα, Patr_RHβ, and Patr_RHγ). In the Patr_RHβ locus, a short version of the gene, which lacked the middle part containing exons 4–8, was observed. The Patr_RHα and Patr_RHβ genes were located on the locations corresponding to Hosa_RHD and Hosa_RHCE, respectively, and Patr_RHγ was in the immediate vicinity of Patr_RHβ. Sequence comparisons revealed high sequence similarity between Patr_RHβ and Hosa_RHCE, while the chimpanzee Rh gene closest to Hosa_RHD was not Patr_RHα but rather Patr_RHγ. The results suggest that rearrangements and gene conversions frequently occurred between these genes and that the classic orthology/paralogy dichotomy no longer holds between human and chimpanzee Rh blood group genes.

Key words: gene duplication phylogeny rearrangement

© The Author(s) 2016. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited. For commercial re-use, please contact journals.permissions@oup.com

FREE PDF GRATIS: Genome Biol Evol

                            Sup. Info.

Compensando os custos de aptidão de mutações sinônimas

Compensating the fitness costs of synonymous mutations

Anna Knöppel, Joakim Näsvall and Dan I. Andersson*

- Author Affiliations

Department of Medical Biochemistry and Microbiology, Uppsala University, Sweden

↵* for correspondence: 

email: Dan.Andersson@imbim.uu.se, 

phone: +46 018 4714175

Received October 29, 2015. Revision received December 16, 2015. Revision received January 21, 2016. Accepted January 22, 2016.

Abstract

Synonymous mutations do not change the sequence of the polypeptide but they may still influence fitness. We investigated in Salmonella enterica how four synonymous mutations in the rpsT gene (encoding ribosomal protein S20) reduce fitness (i.e. growth rate) and the mechanisms by which this cost can be genetically compensated. The reduced growth rates of the synonymous mutants were correlated with reduced levels of the rpsT transcript and S20 protein. In an adaptive evolution experiment these fitness impairments could be compensated by mutations that either caused up-regulation of S20 through increased gene dosage (due to duplications), increased transcription of the rpsT gene (due to an rpoD mutation or mutations in rpsT), or increased translation from the rpsT transcript (due to rpsT mutations). We suggest that the reduced levels of S20 in the synonymous mutants result in production of a defective subpopulation of 30S subunits lacking S20 that reduce protein synthesis and bacterial growth and that the compensatory mutations restore S20 levels and the number of functional ribosomes. Our results demonstrate how specific synonymous mutations can cause substantial fitness reductions and that many different types of intra- and extragenic compensatory mutations can efficiently restore fitness. Furthermore, our study highlights that also synonymous sites can be under strong selection, which may have implications for the use of dN/dS ratios as signature for selection.

© The Author(s) 2016. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited. For commercial re-use, please contact journals.permissions@oup.com

FREE PDF GRATIS: Mol Biol Evol

A cosmologia nem astrofísica é... e cientistas suprimem evidências contrárias?

ΛCDM cosmology: how much suppression of credible evidence, and does the model really lead its competitors, using all evidence?

Richard Lieu

(Submitted on 17 May 2007)

Source/Fonte

Astronomy can never be a hard core physics discipline, because the Universe offers no control experiment, i.e. with no independent checks it is bound to be highly ambiguous and degenerate. Thus e.g. while superluminal motion can be explained by Special Relativity. data on the former can never on their own be used to establish the latter. This is why traditionally astrophysicists have been content with (and proud of) their ability to use known physical laws and processes established in the laboratory to explain celestial phenomena. Cosmology is not even astrophysics: all the principal assumptions in this field are unverified (or unverifiable) in the laboratory, and researchers are quite comfortable with inventing unknowns to explain the unknown. How then could, after fifty years of failed attempt in finding dark matter, the fields of dark matter {\it and now} dark energy have become such lofty priorities in astronomy funding, to the detriment of all other branches of astronomy? I demonstrate in this article that while some of is based upon truth, at least just as much of ΛCDM cosmology has been propped by a paralyzing amount of propaganda which suppress counter evidence and subdue competing models. The recent WMAP3 paper of Spergel et al (2007) will be used as case in point on selective citation. I also show that when all evidence are taken into account, two of the competing models that abolish dark energy and/or dark matter do not trail behind ΛCDM by much. Given all of the above, I believe astronomy is no longer heading towards a healthy future, unless funding agencies re-think their master plans by backing away from such high a emphasis on groping in the dark.

Comments: 14 pages, 3 figures and 3 tables

Subjects: Astrophysics (astro-ph)

Cite as: arXiv:0705.2462 [astro-ph]

(or arXiv:0705.2462v1 [astro-ph] for this version)

Submission history

From: Richard Lieu [view email] 

[v1] Thu, 17 May 2007 13:21:01 GMT (465kb,D)

FREE PDF GRATIS: ArXiv

O oxigênio estava presente na atmosfera há muito mais tempo do que antes presumido

Oxidative elemental cycling under the low O2 Eoarchean atmosphere

Robert Frei, Sean A. Crowe, Michael Bau, Ali Polat, David A. Fowle & Lasse N. Døssing

Scientific Reports 6, Article number: 21058 (2016)

doi:10.1038/srep21058

Download Citation

Geochemistry | Palaeoclimate

Received: 19 June 2015 Accepted: 02 December 2015

Published online: 11 February 2016

Source/Fonte

Abstract

The Great Oxidation Event signals the first large-scale oxygenation of the atmosphere roughly 2.4 Gyr ago. Geochemical signals diagnostic of oxidative weathering, however, extend as far back as 3.3–2.9 Gyr ago. 3.8–3.7 Gyr old rocks from Isua, Greenland stand as a deep time outpost, recording information on Earth’s earliest surface chemistry and the low oxygen primordial biosphere. Here we find fractionated Cr isotopes, relative to the igneous silicate Earth reservoir, in metamorphosed banded iron formations (BIFs) from Isua that indicate oxidative Cr cycling 3.8–3.7 Gyr ago. Elevated U/Th ratios in these BIFs relative to the contemporary crust, also signal oxidative mobilization of U. We suggest that reactive oxygen species were present in the Eoarchean surface environment, under a very low oxygen atmosphere, inducing oxidative elemental cycling during the deposition of the Isua BIFs and possibly supporting early aerobic biology.

FREE PDF GRATIS: Scientific Reports

Koonin e o significado da informação biológica

The meaning of biological information

Eugene V. Koonin

Published 8 February 2016. DOI: 10.1098/rsta.2015.0065

Source/Fonte

Abstract

Biological information encoded in genomes is fundamentally different from and effectively orthogonal to Shannon entropy. The biologically relevant concept of information has to do with ‘meaning’, i.e. encoding various biological functions with various degree of evolutionary conservation. Apart from direct experimentation, the meaning, or biological information content, can be extracted and quantified from alignments of homologous nucleotide or amino acid sequences but generally not from a single sequence, using appropriately modified information theoretical formulae. For short, information encoded in genomes is defined vertically but not horizontally. Informally but substantially, biological information density seems to be equivalent to ‘meaning’ of genomic sequences that spans the entire range from sharply defined, universal meaning to effective meaninglessness. Large fractions of genomes, up to 90% in some plants, belong within the domain of fuzzy meaning. The sequences with fuzzy meaning can be recruited for various functions, with the meaning subsequently fixed, and also could perform generic functional roles that do not require sequence conservation. Biological meaning is continuously transferred between the genomes of selfish elements and hosts in the process of their coevolution. Thus, in order to adequately describe genome function and evolution, the concepts of information theory have to be adapted to incorporate the notion of meaning that is central to biology.

FREE PDF GRATIS: Phil Trans R Soc A

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NOTA DESTE BLOGGER:

A teoria do Design Inteligente é uma teoria de informação desde sua incipiência, e rejeitada veementemente pela comunidade científica. E a agora esta comunidade científica está se rendendo às evidências de que a biologia dos séculos 20 e 21 é uma ciência de informação?

E é a turma do Design Inteligente que impede o avanço da ciência???

Por que afirmamos aqui ser a nova teoria geral da evolução - a Síntese Evolutiva Ampliada/Estendida, lançada em agosto de 2015, uma teoria científica natimorta? É porque ela timidamente aborda a questão da informação complexa especificada.

O bom em ciência é que são as evidências que estabelecem o fato científico e não as teorias.

Charbel Niño El-Hani, meu amigo, lembra que em 2006, após minha palestra sobre Design Inteligente, na Universidade Presbiteriana Mackenzie, em São Paulo, você disse que eu tinha embarcado na canoa furada do Design Inteligente? Lembra de minha resposta? Eu respondi: Charbel, eu estou apostando todas as minhas fichas no cavalo do DI do que apostar no pangaré do Darwin?

Parece que eu estou ganhando a aposta, Charbel...

Marcello Barbieri perguntou: O que é informação?

What is information?

Marcello Barbieri

Published 8 February 2016.DOI: 10.1098/rsta.2015.0060

Source/Fonte

Abstract

Molecular biology is based on two great discoveries: the first is that genes carry hereditary information in the form of linear sequences of nucleotides; the second is that in protein synthesis a sequence of nucleotides is translated into a sequence of amino acids, a process that amounts to a transfer of information from genes to proteins. These discoveries have shown that the information of genes and proteins is the specific linear order of their sequences. This is a clear definition of information and there is no doubt that it reflects an experimental reality. What is not clear, however, is the ontological status of information, and the result is that today we have two conflicting paradigms in biology. One is the ‘chemical paradigm’, the idea that ‘life is chemistry’, or, more precisely, that ‘life is an extremely complex form of chemistry’. The other is the ‘information paradigm’, the view that chemistry is not enough, that ‘life is chemistry plus information’. This implies that there is an ontological difference between information and chemistry, a difference which is often expressed by saying that information-based processes like heredity and natural selection simply do not exist in the world of chemistry. Against this conclusion, the supporters of the chemical paradigm have argued that the concept of information is only a linguistic metaphor, a word that summarizes the result of countless underlying chemical reactions. The supporters of the information paradigm insist that information is a real and fundamental component of the living world, but have not been able to prove this point. As a result, the chemical view has not been abandoned and the two paradigms both coexist today. Here, it is shown that a solution to the ontological problem of information does exist. It comes from the idea that life is artefact-making, that genes and proteins are molecular artefacts manufactured by molecular machines and that artefacts necessarily require sequences and coding rules in addition to the quantities of physics and chemistry. More precisely, it is shown that the production of artefacts requires new observables that are referred to as nominable entities because they can be described only by naming their components in their natural order. From an ontological point of view, in conclusion, information is a nominable entity, a fundamental but not-computable observable.

Footnotes

One contribution of 21 to a theme issue ‘DNA as information’.

Accepted July 1, 2015.

© 2016 The Author(s)

http://royalsocietypublishing.org/licence

Published by the Royal Society. All rights reserved.

Subscription or payment needed/Requer assinatura ou pagamento.

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NOTA DESTE BLOGGER:

Faz parte do arcabouço teórico do Design Inteligente a informação complexa e especificada. E alguns cientistas da Nomenklatura científica e a Galera dos meninos e meninas de Darwin teimam no mantra de a TDI ser pseudociência, criacionismo disfarçado y otras cositas mais.

Desde os anos 1990s, os teóricos, proponentes e defensores da teoria do Design Inteligente afirmamos da importância da informação em biologia evolucionária. Razão? A biologia dos séculos 20 e 21 é uma ciência da informação!

Fonte

Fui, nem sei por que, sorrindo tipo o gato de Cheshire e queria ver a cara desses que tripudiaram da teoria do Design Inteligente.

Lançado novo site do Darwin Correspondence Project

Source/Fonte

O Darwin Correspondence Day celebrou o Dia de Darwin (12 de Fevereiro) lançando um novo site - são mais de 8.500 cartas (das 15.000 arquivadas) e artigos online à disposição dos estudiosos e interessados. Pela primeira vez, centenas de cartas datadas de 1871 estão disponíveis.

A biologia do barroco - novo livro de Michael Dento sobre a prevalecente crise epistêmica do darwinismo

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Leia o novo livro de Michael Denton - Evolution: Still a Theory in Crisis.

As implicações astrofísicas da descoberta das ondas gravitacionais

ASTROPHYSICAL IMPLICATIONS OF THE BINARY BLACK HOLE MERGER GW150914

B. P. Abbott1, R. Abbott1, T. D. Abbott2, M. R. Abernathy1, F. Acernese3,4, K. Ackley5, C. Adams6, T. Adams7, P. Addesso3, R. X. Adhikari1

Published 2016 February 11 • © 2016. The American Astronomical Society. All rights reserved. • The Astrophysical Journal Letters, Volume 818, Number 2

Source/Fonte: New Scientist

Abstract

The discovery of the gravitational-wave (GW) source GW150914 with the Advanced LIGO detectors provides the first observational evidence for the existence of binary black hole (BH) systems that inspiral and merge within the age of the universe. Such BH mergers have been predicted in two main types of formation models, involving isolated binaries in galactic fields or dynamical interactions in young and old dense stellar environments. The measured masses robustly demonstrate that relatively "heavy" BHs ($\gtrsim 25$ ${M}_{\odot }$) can form in nature. This discovery implies relatively weak massive-star winds and thus the formation of GW150914 in an environment with a metallicity lower than about 1/2 of the solar value. The rate of binary-BH (BBH) mergers inferred from the observation of GW150914 is consistent with the higher end of rate predictions ($\gtrsim 1$ Gpc−3 yr−1) from both types of formation models. The low measured redshift ($z\simeq 0.1$) of GW150914 and the low inferred metallicity of the stellar progenitor imply either BBH formation in a low-mass galaxy in the local universe and a prompt merger, or formation at high redshift with a time delay between formation and merger of several Gyr. This discovery motivates further studies of binary-BH formation astrophysics. It also has implications for future detections and studies by Advanced LIGO and Advanced Virgo, and GW detectors in space.

FREE PDF GRATIS: The Astrophysical Journal Letters.

Como são detectadas as ondas gravitacionais

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Explicação por Nergis Mavalvala, física do MIT, em 2015.

O artigo sobre a detecção de ondas gravitacionais pelo LIGO

Observation of Gravitational Waves from a Binary Black Hole Merger

B. P. Abbott et al.*

(LIGO Scientific Collaboration and Virgo Collaboration)

(Received 21 January 2016; published 11 February 2016)

Abstract

On September 14, 2015 at 09:50:45 UTC the two detectors of the Laser Interferometer Gravitational-Wave Observatory simultaneously observed a transient gravitational-wave signal. The signal sweeps upwards in frequency from 35 to 250 Hz with a peak gravitational-wave strain of 1.0 × 10−21. It matches the waveform predicted by general relativity for the inspiral and merger of a pair of black holes and the ringdown of the resulting single black hole. The signal was observed with a matched-filter signal-to-noise ratio of 24 and a false alarm rate estimated to be less than 1 event per 203 000 years, equivalent to a significance greater than 5.1σ. The source lies at a luminosity distance of 410þ160

−180 Mpc corresponding to a redshift z ¼ 0.09þ0.03 −0.04 . In the source frame, the initial black hole masses are 36þ5 −4M⊙ and 29þ4 −4M⊙, and the final black hole mass is 62þ4 −4M⊙, with 3.0þ0.5 −0.5M⊙c2 radiated in gravitational waves. All uncertainties define 90% credible intervals. These observations demonstrate the existence of binary stellar-mass black hole systems. This is the first direct detection of gravitational waves and the first observation of a binary black hole merger.

DOI: 10.1103/PhysRevLett.116.061102

FREE PDF GRATIS: Physical Review Letters

Uma pergunta fundamental em biologia sistêmica

Source/Fonte

Diante das descobertas e avanços em biologia, e tendo lido muitos artigos, e não tendo encontrado resposta, alguém, especialmente biólogos em universidades públicas e privadas, saberia me dizer se a pergunta fundamental em biologia sistêmica já teve alguma resposta?

A pergunta é:

Como a variação induzida por mutações em uma rede molecular gera a variação no fenótipo resultante?

Respostas cientificamente fundamentadas e remetendo para a literatura especializada para neddybr@gmail.com

Muito obrigado! 

O enigma persistente do queixo humano

Evolutionary Anthropology: Issues, News, and Reviews

Volume 25, Issue 1, pages 20–35, January/February 2016

The enduring puzzle of the human chin

James D. Pampush and David J. Daegling

Article first published online: 22 JAN 2016

DOI: 10.1002/evan.21471

© 2016 Wiley Periodicals, Inc.

James D. Pampush is a postdoctoral associate in the Evolutionary Anthropology Department of Duke University. His research interests include primate orofacial anatomy and evolution. His recently completed dissertation reexamined the evolutionary scenarios underpinning emergence of the modern human chin. E-mail: jdp47@duke.edu

David J. Daegling is professor of Anthropology at the University of Florida. His current research focuses on skeletal biomechanics as part of the multi-institutional Taï Monkey Project (Côte d'Ivoire).

Source/Fonte

Keywords:

spandrel; adaptation; mastication; sexual selection; speech; hypofunction

Abstract

Although modern humans are considered to be morphologically distinct from other living primates because of our large brains, dexterous hands, and bipedal gait, all of these features are found among extinct hominins. The chin, however, appears to be a uniquely modern human trait. Probably because of the chin's exclusivity, many evolutionary scenarios have been proposed to explain its origins. To date, researchers have developed adaptive hypotheses relating chins to speech, mastication, and sexual selection; still others see it as a structural artifact tangentially related to complex processes involving evolutionary retraction of the midfacial skeleton. Consensus has remained elusive, partly because hypotheses purporting to explain how this feature developed uniquely in modern humans are all fraught with theoretical and/or empirical shortcomings. Here we review a century's worth of chin hypotheses and discuss future research avenues that may provide greater insight into this human peculiarity.

FREE PDF GRATIS: Evolutionary Anthropology

Pontuação combinatória de redes filogenéticas

Combinatorial Scoring of Phylogenetic Networks∗

Nikita Alexeev and Max A. Alekseyev

George Washington University, Washington, D.C., U.S.A.

Source/Fonte

Abstract

Construction of phylogenetic trees and networks for extant species from their characters represents one of the key problems in phylogenomics. While solution to this problem is not always uniquely defined and there exist multiple methods for tree/network construction, it becomes important to measure how well constructed networks capture the given character relationship across the species. 

In the current study, we propose a novel method for measuring the specificity of a given phylogenetic network in terms of the total number of distributions of character states at the leaves that the network may impose. While for binary phylogenetic trees, this number has an exact formula and depends only on the number of leaves and character states but not on the tree topology, the situation is much more complicated for non-binary trees or networks. Nevertheless, we develop an algorithm for combinatorial enumeration of such distributions, which is applicable for arbitrary trees and networks under some reasonable assumptions.

FREE PDF GRATIS: ArXiv

Os super genes e o papel deles na evolução

REVIEW

Supergenes and their role in evolution

MJ Thompson 1,2 and CD Jiggins 1

Source/Fonte

Abstract

Adaptation is commonly a multidimensional problem, with changes in multiple traits required to match a complex environment. This is epitomized by balanced polymorphisms in which multiple phenotypes co-exist and are maintained in a population by a balance of selective forces. Consideration of such polymorphisms led to the concept of the supergene, where alternative phenotypes in a balanced polymorphism segregate as if controlled by a single genetic locus, resulting from tight genetic linkage between multiple functional loci. Recently, the molecular basis for several supergenes has been resolved. Thus, major chromosomal inversions have been shown to be associated with polymorphisms in butterflies, ants and birds, offering a mechanism for localised reduction in recombination. In several examples of plant self-incompatibility, the functional role of multiple elements within the supergene architecture has been demonstrated, conclusively showing that balanced polymorphism can be maintained at multiple coadapted and tightly linked elements. Despite recent criticism, we argue that the supergene concept remains relevant and is more testable than ever with modern molecular methods.

Heredity (2014) 113, 1–8; doi:10.1038/hdy.2014.20; published online 19 March 2014

FREE PDF GRATIS: Heredity

O vento não será a tua herança

DISINHERIT THE WIND from Matt Chait on Vimeo.

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Matt Chait, dramaturgo e artista residente em Los Angeles vira de cabeça o filme O vento será a tua herança - mais uma peça de propaganda do que história qua história sobre o Processo do Macaco de Scopes, e acrescentou mais um personagem à estória: Robert Hawkins (soa como Richard Dawkins...).

Enfim, uma maneira de ironizar o descompasso com a verdade histórica do Processo de Scopes retratado pelo filme O vento será tua herança. 

Nova pesquisa contesta o papel de Júpiter como escudo planetário protetor da Terra

Jupiter: Cosmic Jekyll and Hyde

To cite this article:

Grazier Kevin R.. Astrobiology. January 2016, 16(1): 23-38. doi:10.1089/ast.2015.1321.

Published in Volume: 16 Issue 1: January 20, 2016

Online Ahead of Print: December 23, 2015

Author information

Kevin R. Grazier

Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California.

Address correspondence to:

Kevin R. Grazier

Jet Propulsion Laboratory

California Institute of Technology

Pasadena, CA

E-mail: kevin_grazier@yahoo.com

Submitted 17 March 2015 Accepted 18 July 2015 

Source/Fonte: NASA

Abstract

It has been widely reported that Jupiter has a profound role in shielding the terrestrial planets from comet impacts in the Solar System, and that a jovian planet is a requirement for the evolution of life on Earth. To evaluate whether jovians, in fact, shield habitable planets from impacts (a phenomenon often referred to as the “Jupiter as shield” concept), this study simulated the evolution of 10,000 particles in each of the jovian inter-planet gaps for the cases of full-mass and embryo planets for up to 100 My. The results of these simulations predict a number of phenomena that not only discount the “Jupiter as shield” concept, they also predict that in a Solar System like ours, large gas giants like Saturn and Jupiter had a different, and potentially even more important, role in the evolution of life on our planet by delivering the volatile-laden material required for the formation of life.

The simulations illustrate that, although all particles occupied “non-life threatening” orbits at their onset of the simulations, a significant fraction of the 30,000 particles evolved into Earth-crossing orbits. A comparison of multiple runs with different planetary configurations revealed that Jupiter was responsible for the vast majority of the encounters that “kicked” outer planet material into the terrestrial planet region, and that Saturn assisted in the process far more than has previously been acknowledged. Jupiter also tends to “fix” the aphelion of planetesimals at its orbit irrespective of their initial starting zones, which has the effect of slowing their passages through the inner Solar System, and thus potentially improving the odds of accretion of cometary material by terrestrial planets. As expected, the simulations indicate that the full-mass planets perturb many objects into the deep outer Solar System, or eject them entirely; however, planetary embryos also did this with surprising efficiency. Finally, the simulations predict that Jupiter's capacity to shield or intercept Earth-bound comets originating in the outer Solar System is poor, and that the importance of jovian planets on the formation of life is not that they act as shields, but rather that they deliver life-enabling volatiles to the terrestrial planets. 

Key Words: Asteroid—Comets—Interstellar meteorites—Extrasolar terrestrial planets—Simulation. 

Astrobiology 16, 23–38.

FREE PDF GRATIS: Astrobiology

IsisCB Explore: um serviço Open Access de localização de artigos, dissertações, teses e pesquisas em História da Ciência

Please consider using the *IsisCB Explore History of Science Index* (isiscb.org/explore) for your research, and encourage your library or department to add it to their list of resources. Accessible to anyone on the web, *IsisCB Explore* is a completely open access service made possible by the History of Science Society with support from the University of Oklahoma.

*IsisCB Explore* opens up bibliographical research in the history of science, technology, and medicine. It is designed for students, scholars, librarians, and the general public. Users will find the data architecture intuitive and powerful, and librarians can trust that it will guide researchers to the best literature in the discipline.

Based on the 100-year-old *Isis Current Bibliography of the History of Science*—the largest and most comprehensive in its field—it is supported by the discipline's flagship society, the History of Science Society. It will be expanded and updated annually.

Key features include:

- Nearly 200,000 interlinked bibliographic citations to books, chapters, articles, dissertations, and reviews from the *Isis Bibliography of the History of Science* 1974 to present. Annually updated.

- An authority index of over 150,000 curated entries. Includes historical concepts, persons, and institutions. Also indexes scholars, publishers, journals, and degree granting institutions.

- A navigation interface built specifically for history of science research. Enables focused searches on ancient, medieval, modern and non-Western topics.

- A state-of-the-art network architecture with complex interlinking of citation and authority records.

- Integrated social media tools, including public user comments as well as Twitter and Facebook sharing.

- User accounts with the ability to save searches.

- Zotero integration. Allows users to save individual citations as well as collected results.

- Automated access, with a REST API.

- A search widget for your website.

- *Coming soon:* A link resolver, giving library patrons immediate access to your library’s holdings.

There are some instructional videos on the IsisCB Explore YouTube Channel 

<https://www.youtube.com/channel/UC2z3H0zE-0YISH9zu9jCC3g>. 

The introductory video 

<https://www.youtube.com/watch?v=ntqtn0tyy-E> gives you a quick overview. You can find more information about the history of the Isis

Bibliography on the main site: isiscb.org.

Contact Stephen Weldon (spweldon@ou.edu) with questions.

Stephen P. Weldon

Assistant Professor of History of Science

Editor, Isis Bibliography of the History of Science

Department of History of Science

University of Oklahoma

601 Elm, Room 618

Norman, OK 73019-3106

website: stephenpweldon.com

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NOTA DESTE BLOGGER:

Até que enfim, além do Google Scholar, surgiu um website de buscas sobre História da Ciência Open Access. Milhares de historiadores de ciência agora vão poder continuar suas pesquisas com mais facilidade e sem precisar se deslocar frequentemente para as bibliotecas universitárias.

Parabéns!!!

Pesquisadores desclassificam os dinossauros como sendo os tataravós das aves

Journal of Ornithology

October 2014, Volume 155, Issue 4, pp 841-851

First online: 09 July 2014

Jurassic archosaur is a non-dinosaurian bird

Stephen A. Czerkas, Alan Feduccia

Source/Fonte

Abstract

Re-examination utilizing Keyence 3D digital microscopy and low angled illumination of the fossil Scansoriopteryx, a problematic sparrow-size pre-Archaeopteryx specimen from the Jurassic Daohugou Biotas, provides new evidence which challenges the widely accepted hypothesis that birds are derived from dinosaurs in which avian flight originated from cursorial forms. Contrary to previous interpretations in which Scansoriopteryx was considered to be a coelurosaurian theropod dinosaur, the absence of fundamental dinosaurian characteristics demonstrates that it was not derived from a dinosaurian ancestry and should not be considered as a theropod dinosaur. Furthermore, the combination in which highly plesiomorphic non-dinosaurian traits are retained along with highly derived features, yet only the beginnings of salient birdlike characteristics, indicates that the basal origins of Aves stemmed from outside the Dinosauria and further back to basal archosaurs. Impressions of primitive elongate feathers on the forelimbs and hindlimbs suggest that Scansoriopteryx represents a basal form of “tetrapteryx” in which incipient aerodynamics involving parachuting or gliding was possible. Along with unique adaptations for an arboreal lifestyle, Scansoriopteryx fulfills predictions from the early twentieth century that the ancestors of birds did not evolve from dinosaurs, and instead were derived from earlier arboreal archosaurs which originated flight according to the traditional trees-down scenario.

Keywords

Scansoriopteryx Epidendrosaurus Theropod Archosaur Daohugou Biota Jurassic

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Uma visão CRISPR de desenvolvimento

A CRISPR view of development

Melissa M. Harrison 1, Brian V. Jenkins 2, Kate M. O’Connor-Giles 3,4 and Jill Wildonger 2

- Author Affiliations

1Department of Biomolecular Chemistry, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53706, USA;

2Biochemistry Department, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA;

3Laboratory of Genetics,

4Laboratory of Cell and Molecular Biology, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA

Corresponding author: wildonger@wisc.edu

Source/Fonte

Abstract

The CRISPR (clustered regularly interspaced short palindromic repeat)–Cas9 (CRISPR-associated nuclease 9) system is poised to transform developmental biology by providing a simple, efficient method to precisely manipulate the genome of virtually any developing organism. This RNA-guided nuclease (RGN)-based approach already has been effectively used to induce targeted mutations in multiple genes simultaneously, create conditional alleles, and generate endogenously tagged proteins. Illustrating the adaptability of RGNs, the genomes of >20 different plant and animal species as well as multiple cell lines and primary cells have been successfully modified. Here we review the current and potential uses of RGNs to investigate genome function during development.

Keywords

CRISPR Cas9 development genome editing genome engineering RNA-guided nuclease

Footnotes

Article is online at 

http://www.genesdev.org/cgi/doi/10.1101/gad.248252.114.

Freely available online through the Genes & Development Open Access option.

© 2014 Harrison et al.; Published by Cold Spring Harbor Laboratory Press

This article, published in Genes & Development, is available under a Creative Commons License (Attribution-NonCommercial 4.0 International), as described at http://creativecommons.org/licenses/by-nc/4.0/.

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Colocando limites em ruído bioquímico

Constraints on Fluctuations in Sparsely Characterized Biological Systems

Andreas Hilfinger,1 Thomas M. Norman, 1 Glenn Vinnicombe, 2 and Johan Paulsson 1,*

1 Department of Systems Biology, Harvard University, 200 Longwood Avenue, Boston, Massachusetts 02115, USA 

2 Department of Engineering, University of Cambridge, Cambridge CB2 1PZ, United Kingdom

(Received 27 August 2015; published 1 February 2016)

Source/Fonte

Abstract

Biochemical processes are inherently stochastic, creating molecular fluctuations in otherwise identical cells. Such “noise” is widespread but has proven difficult to analyze because most systems are sparsely characterized at the single cell level and because nonlinear stochastic models are analytically intractable. Here, we exactly relate average abundances, lifetimes, step sizes, and covariances for any pair of components in complex stochastic reaction systems even when the dynamics of other components are left unspecified. Using basic mathematical inequalities, we then establish bounds for whole classes of systems. These bounds highlight fundamental trade-offs that show how efficient assembly processes must invariably exhibit large fluctuations in subunit levels and how eliminating fluctuations in one cellular component requires creating heterogeneity in another.

FREE PDF GRATIS: Physical Review Letters