Os cientistas capturaram o momento extraordinário "uau" da fertilização

The zinc spark is an inorganic signature of human egg activation

Francesca E. Duncan, Emily L. Que, Nan Zhang, Eve C. Feinberg, Thomas V. O’Halloran & Teresa K. Woodruff

Scientific Reports 6, Article number: 24737 (2016) doi:10.1038/srep24737

Download Citation 

Predictive markers Reproductive biology

Received: 03 December 2015 Accepted: 01 April 2016 Published online: 26 April 2016

Abstract

Egg activation refers to events required for transition of a gamete into an embryo, including establishment of the polyspermy block, completion of meiosis, entry into mitosis, selective recruitment and degradation of maternal mRNA, and pronuclear development. Here we show that zinc fluxes accompany human egg activation. We monitored calcium and zinc dynamics in individual human eggs using selective fluorophores following activation with calcium-ionomycin, ionomycin, or hPLCζ cRNA microinjection. These egg activation methods, as expected, induced rises in intracellular calcium levels and also triggered the coordinated release of zinc into the extracellular space in a prominent “zinc spark.” The ability of the gamete to mount a zinc spark response was meiotic-stage dependent. Moreover, chelation of intracellular zinc alone was sufficient to induce cell cycle resumption and transition of a meiotic cell into a mitotic one. Together, these results demonstrate critical functions for zinc dynamics and establish the zinc spark as an extracellular marker of early human development.

FREE PDF GRATIS: Scientific Reports

50 anos de desafios científicos à teoria da evolução: Relembrando o Simpósio de Wistar

A teoria da evolução de Darwin através da seleção natural e n mecanismos evolucionários de A a Z (vai que um falhe), não fecha na matemática! Leiam este livro de 50 anos atrás (e a Nomenklatura científica e a Galera de meninos e meninas de Darwin dizem que não houve e nem há crise epistêmica na teoria da evolução?): Mathematical Challenges to the Neo-Darwinian Interpretation of Evolution (US$ 199,95), e vejam que os problemas não foram respondidos no contexto de justificação teórica, e aumentaram cada vez mais!

Porta de entrada para o cérebro: mero acaso, fortuita necessidade ou design inteligente?

Structural insights into the transport mechanism of the human sodium-dependent lysophosphatidylcholine transporter Mfsd2a

Debra Q.Y. Quek1, Long N. Nguyen2, Hao Fan3 and David L. Silver1*

- Author Affiliations

1 Duke-NUS Medical School, Singapore;

2 National University of Singapore, Singapore;

3 A*STAR, Singapore

↵* Corresponding author; email: david.silver@duke-nus.edu.sg

Author contributions: D.L.S., D.Q.Q., and H.F. designed research; D.Q.Q. and H.F. performed research; L.N.N performed experiments for Fig. 3H; D.Q.Q. and H.F. performed structural modelling and analysis. D.Q.Q., D.L.S., and H.F. wrote the paper.

The structural model of transporter MFSD2A

Abstract

Major Facilitator Superfamily Domain containing 2A (Mfsd2a) was recently characterized as a sodium-dependent lysophosphatidylcholine (LPC) transporter expressed at the blood-brain barrier endothelium. It is the primary route for importation of docosohexaenoic acid and other long-chain fatty acids into foetal and adult brain, and is essential for mouse and human brain growth and function. Remarkably, Mfsd2a is the first identified MFS family member that uniquely transports lipids, implying that Mfsd2a harbours unique structural features and transport mechanism. Here, we present three 3D structural models of human Mfsd2a derived by homology modelling using MelB- and LacY-based crystal structures, and refined by biochemical analysis. All models revealed 12 transmembrane helices and connecting loops, and represented the partially outward-open, outward-partially occluded, and inward-open states of the transport cycle. In addition to a conserved sodium-binding site, three unique structural features were identified: A phosphate headgroup binding site, a hydrophobic cleft to accommodate a hydrophobic hydrocarbon tail, and three sets of ionic locks that stabilize the outward-open conformation. Ligand docking studies and biochemical assays identified Lys436 as a key residue for transport. It is seen forming a salt bridge with the negative charge on the phosphate headgroup. Importantly, Mfsd2a transported structurally related acylcarnitines but not a lysolipid without a negative charge, demonstrating the necessity of a negative charged headgroup interaction with Lys436 for transport. These findings support a novel transport mechanism by which LPCs are flipped within the transporter cavity by pivoting about Lys436 leading to net transport from the outer to the inner leaflet of the plasma membrane.

brain metabolism drug transport lysophospholipid membrane protein polyunsaturated fatty acid (PUFA) X-ray crystallography blood-brain barrier docosahexaenoic acid membrane transporter microcephaly

Received February 9, 2016. Accepted March 4, 2016.

Copyright © 2016, The American Society for Biochemistry and Molecular Biology

FREE PDF GRATIS: The Journal of Biological Chemistry

Mutação e o excepcionalismo humano: nossa carga genética futura

Mutation and Human Exceptionalism: Our Future Genetic Load

Michael Lynch

GENETICS March 1, 2016 vol. 202 no. 3 869-875; 

DOI: 10.1534/genetics.115.180471

Abstract

Although the human germline mutation rate is higher than that in any other well-studied species, the rate is not exceptional once the effective genome size and effective population size are taken into consideration. Human somatic mutation rates are substantially elevated above those in the germline, but this is also seen in other species. What is exceptional about humans is the recent detachment from the challenges of the natural environment and the ability to modify phenotypic traits in ways that mitigate the fitness effects of mutations, e.g., precision and personalized medicine. This results in a relaxation of selection against mildly deleterious mutations, including those magnifying the mutation rate itself. The long-term consequence of such effects is an expected genetic deterioration in the baseline human condition, potentially measurable on the timescale of a few generations in westernized societies, and because the brain is a particularly large mutational target, this is of particular concern. Ultimately, the price will have to be covered by further investment in various forms of medical intervention. Resolving the uncertainties of the magnitude and timescale of these effects will require the establishment of stable, standardized, multigenerational measurement procedures for various human traits.

FREE PDF GRATIS: Genetics

Porque a evolução humana deve ser uma ciência básica para estudantes de medicina e psicologia

Why human evolution should be a basic science for medicine and psychology students

Paola Palanza & Stefano Parmigiani

Department of Neuroscience, Unit of Behavioral Biology, University of Parma, Viale delle Scienze 11A, 43100 Parma, Italy

e-mail: paola.palanza@unipr.it

Summary

Based on our teaching experience in medicine and psychology degree programs, we examine different aspects of human evolution that can help students to understand how the human body and mind work and why they are vulnerable to certain diseases. Three main issues are discussed: 1) the necessity to consider not only the mechanisms, i.e. the “proximate causations”, implicated in biological processes but also why these mechanisms have evolved, i.e. the “ultimate causations” or “adaptive significance”, to understand the functioning and malfunctioning of human body and mind; 2) examples of how human vulnerabilities to disease are caused by phylogenetic constraints, evolutionary tradeoffs reflecting the combined actions of natural and sexual selection, and/or mismatch between past and present environment (i.e., evolution of the eye, teeth and diets, erect posture and their consequences); 3) human pair-bonding and parent-offspring relationships as the result of socio-sexual selection and evolutionary compromises between cooperation and conflict. These psychobiological mechanisms are interwoven with our brain developmental plasticity and the effects of culture in shaping our behavior and mind, and allow a better understanding of functional (normal) and dysfunctional (pathological) behaviors. Thus, because the study of human evolution offers a powerful framework for clinical practice and research, the curriculum studiorum of medical and psychology students should include evolutionary biology and human phylogeny.

Keywords - Science education, Natural selection, Sexual selection, Ultimate causation, Human health, Darwinian medicine.

FREE PDF GRATIS: Journal of Anthropological Sciences

Novos insights na regulação de genes através da caracterização do complexo NuRD de repressão

The structure of the core NuRD repression complex provides insights into its interaction with chromatin

Christopher J Millard Niranjan Varma Almutasem Saleh Kyle Morris Peter J Watson Andrew R Bottrill Louise Fairall Corinne J Smith John WR Schwabe 

University of Leicester, United Kingdom; University of Warwick, United Kingdom

DOI: http://dx.doi.org/10.7554/eLife.13941

Published April 21, 2016 Cite as eLife 2016;5:e13941

Abstract

The NuRD complex is a multi-protein transcriptional corepressor that couples histone deacetylase and ATP-dependent chromatin remodelling activities. The complex regulates the higher-order structure of chromatin, and has important roles in the regulation of gene expression, DNA damage repair and cell differentiation. HDACs 1 and 2 are recruited by the MTA1 corepressor to form the catalytic core of the complex. The histone chaperone protein RBBP4, has previously been shown to bind to the carboxy-terminal tail of MTA1. We show that MTA1 recruits a second copy of RBBP4. The crystal structure reveals an extensive interface between MTA1 and RBBP4. An EM structure, supported by SAXS and crosslinking, reveals the architecture of the dimeric HDAC1:MTA1:RBBP4 assembly which forms the core of the NuRD complex. We find evidence that in this complex RBBP4 mediates interaction with histone H3 tails, but not histone H4, suggesting a mechanism for recruitment of the NuRD complex to chromatin.

DOI: http://dx.doi.org/10.7554/eLife.13941.001

eLife digest

The correct regulation of our genes is essential for life. Genes are actively switched on or off through the action of assemblies of proteins that act together as molecular machines. Some of these machines alter the way that DNA is packaged inside cells. Packaged DNA – called chromatin – consists of DNA wrapped around proteins called histones, which together form structures called nucleosomes. Changing how tightly nucleosomes are packed together can alter whether a gene is active: tighter packing makes it harder to access the genes in that stretch of DNA and therefore inactivates them.

In humans, an assembly of proteins called the NuRD complex makes chromatin more compact by removing acetyl groups from nucleosomes. This complex is important for early development and for the stability and repair of our genes. Three proteins make up its core: HDAC1, which removes the acetyl group from the nucleosome; MTA1, which acts as a scaffold to hold the complex together; and RBBP4, which enables the complex to interact with nucleosomes.

Understanding how protein complexes are assembled tells us a lot about how they work. Millard et al. have therefore used a number of structural techniques to investigate the three-dimensional architecture of the three core proteins in the NuRD complex. The resulting structures have revealed how the HDAC1, MTA1 and RBBP4 proteins interact to influence how the complex is recruited to nucleosomes. The next step will be to assemble all the remaining proteins of the NuRD complex to understand its architecture as a whole.

DOI: http://dx.doi.org/10.7554/eLife.13941.002

FREE PDF GRATIS: eLIFE

Novos fósseis do Mioceno e a história dos pinguins na Austrália

New Miocene Fossils and the History of Penguins in Australia

Travis Park , Erich M. G. Fitzgerald, Stephen J. Gallagher, Ellyn Tomkins, Tony Allan

Published: April 26, 2016http://dx.doi.org/10.1371/journal.pone.0153915

Abstract

Australia has a fossil record of penguins reaching back to the Eocene, yet today is inhabited by just one breeding species, the little penguin Eudyptula minor. The description of recently collected penguin fossils from the re-dated upper Miocene Port Campbell Limestone of Portland (Victoria), in addition to reanalysis of previously described material, has allowed the Cenozoic history of penguins in Australia to be placed into a global context for the first time. Australian pre-Quaternary fossil penguins represent stem taxa phylogenetically disparate from each other and E. minor, implying multiple dispersals and extinctions. Late Eocene penguins from Australia are closest to contemporaneous taxa in Antarctica, New Zealand and South America. Given current material, the Miocene Australian fossil penguin fauna is apparently unique in harbouring ‘giant penguins’ after they went extinct elsewhere; and including stem taxa until at least 6 Ma, by which time crown penguins dominated elsewhere in the southern hemisphere. Separation of Australia from Antarctica during the Palaeogene, and its subsequent drift north, appears to have been a major event in Australian penguin biogeography. Increasing isolation through the Cenozoic may have limited penguin dispersal to Australia from outside the Australasian region, until intensification of the eastwards-flowing Antarctic Circumpolar Current in the mid-Miocene established a potential new dispersal vector to Australia.

Citation: Park T, Fitzgerald EMG, Gallagher SJ, Tomkins E, Allan T (2016) New Miocene Fossils and the History of Penguins in Australia. PLoS ONE 11(4): e0153915. doi:10.1371/journal.pone.0153915

Editor: Nicholas Pyenson, Smithsonian Institution, UNITED STATES

Received: July 24, 2015; Accepted: April 6, 2016; Published: April 26, 2016

Copyright: © 2016 Park 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.

Data Availability: All relevant data are within the paper and its Supporting Information files.

Funding: Grant number: DP0558150, Australian Research Council, funder's website: www.arc.gov.au, author who received funding: SJG and ET. Funding was for fieldwork associated with geologic data collection and subsequent stratigraphic analyses only. 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.

FREE PDF GRATIS: PLoS One

Os elos perdidos na origem da vida podem ter se desenvolvido em poças d'água

Spontaneous formation and base pairing of plausible prebiotic nucleotides in water

Brian J. Cafferty, David M. Fialho, Jaheda Khanam, Ramanarayanan Krishnamurthy & Nicholas V. Hud

Affiliations Contributions Corresponding author

Nature Communications 7, Article number: 11328 doi:10.1038/ncomms11328

Received 02 August 2015 Accepted 16 March 2016 Published 25 April 2016

Abstract

The RNA World hypothesis presupposes that abiotic reactions originally produced nucleotides, the monomers of RNA and universal constituents of metabolism. However, compatible prebiotic reactions for the synthesis of complementary (that is, base pairing) nucleotides and mechanisms for their mutual selection within a complex chemical environment have not been reported. Here we show that two plausible prebiotic heterocycles, melamine and barbituric acid, form glycosidic linkages with ribose and ribose-5-phosphate in water to produce nucleosides and nucleotides in good yields. Even without purification, these nucleotides base pair in aqueous solution to create linear supramolecular assemblies containing thousands of ordered nucleotides. Nucleotide anomerization and supramolecular assemblies favour the biologically relevant β-anomer form of these ribonucleotides, revealing abiotic mechanisms by which nucleotide structure and configuration could have been originally favoured. These findings indicate that nucleotide formation and selection may have been robust processes on the prebiotic Earth, if other nucleobases preceded those of extant life.

Subject terms: Chemical sciences Organic chemistry Chemical biology

FREE PDF GRATIS: Nature Communications

Como e porque os organismos unicelulares evoluíram em vida multicelular

The Gonium pectorale genome demonstrates co-option of cell cycle regulation during the evolution of multicellularity

Erik R. Hanschen, Tara N. Marriage, Patrick J. Ferris, Takashi Hamaji, Atsushi Toyoda, Asao Fujiyama, Rafik Neme, Hideki Noguchi, Yohei Minakuchi, Masahiro Suzuki, Hiroko Kawai-Toyooka, David R. Smith, Halle Sparks, Jaden Anderson, Robert Bakarić, Victor Luria, Amir Karger, Marc W. Kirschner, Pierre M. Durand, Richard E. Michod et al.

Affiliations Contributions Corresponding authors

Nature Communications 7, Article number: 11370 doi:10.1038/ncomms11370

Received 26 January 2016 Accepted 18 March 2016 Published 22 April 2016

Abstract

The transition to multicellularity has occurred numerous times in all domains of life, yet its initial steps are poorly understood. The volvocine green algae are a tractable system for understanding the genetic basis of multicellularity including the initial formation of cooperative cell groups. Here we report the genome sequence of the undifferentiated colonial alga, Gonium pectorale, where group formation evolved by co-option of the retinoblastoma cell cycle regulatory pathway. Significantly, expression of the Gonium retinoblastoma cell cycle regulator in unicellular Chlamydomonas causes it to become colonial. The presence of these changes in undifferentiated Gonium indicates extensive group-level adaptation during the initial step in the evolution of multicellularity. These results emphasize an early and formative step in the evolution of multicellularity, the evolution of cell cycle regulation, one that may shed light on the evolutionary history of other multicellular innovations and evolutionary transitions.

Subject terms: Biological sciences Evolution Genetics

FREE PDF GRATIS: Nature Communications

Celebrando o Dia do DNA 2016: mais de 100 artigos acesso livre!

Celebrating DNA Day 2016

Read top articles published in Springer Nature Genetics Journals

We are pleased to announce that we are supporting the DNA Day 2016 celebrated on April 25. This annual event commemorates the discovery of DNA's double helix back in 1953 and celebrates the completion of the Human Genome Project in 2003.

Springer Nature is opening top research articles about key scientific developments in Genetics. The selected articles are published in Springer, BioMed Central and Nature Publishing Group journals

Take our DNA Day Quiz or check out our 'Ask a Geneticist' Q&A.

Enjoy and spread the word!

A divergência dos cromossomos Y de neandertais e humanos modernos

The Divergence of Neandertal and Modern Human Y Chromosomes

Fernando L. Mendez correspondence email, G. David Poznik, Sergi Castellano, Carlos D. Bustamante correspondence email

Open Access

DOI: http://dx.doi.org/10.1016/j.ajhg.2016.02.023

Publication History Published: April 7, 2016 Accepted: February 26, 2016 Received: December 22, 2015

User License

Creative Commons Attribution (CC BY 4.0)

Relationship of Neandertal Y Chromosome to Those of Modern Humans

The genealogy (red tree) can be parsimoniously explained as mirroring the population divergence (gray tree). We find no evidence for (a) a highly divergent super-archaic origin of the Neandertal Y chromosome, (b) ancient gene flow post-dating the population split, or (c) relatively recent introgression of a modern human Y chromosome into the Neandertal population.

Source/Fonte

Summary

Sequencing the genomes of extinct hominids has reshaped our understanding of modern human origins. Here, we analyze ∼120 kb of exome-captured Y-chromosome DNA from a Neandertal individual from El Sidrón, Spain. We investigate its divergence from orthologous chimpanzee and modern human sequences and find strong support for a model that places the Neandertal lineage as an outgroup to modern human Y chromosomes—including A00, the highly divergent basal haplogroup. We estimate that the time to the most recent common ancestor (TMRCA) of Neandertal and modern human Y chromosomes is ∼588 thousand years ago (kya) (95% confidence interval [CI]: 447–806 kya). This is ∼2.1 (95% CI: 1.7–2.9) times longer than the TMRCA of A00 and other extant modern human Y-chromosome lineages. This estimate suggests that the Y-chromosome divergence mirrors the population divergence of Neandertals and modern human ancestors, and it refutes alternative scenarios of a relatively recent or super-archaic origin of Neandertal Y chromosomes. The fact that the Neandertal Y we describe has never been observed in modern humans suggests that the lineage is most likely extinct. We identify protein-coding differences between Neandertal and modern human Y chromosomes, including potentially damaging changes to PCDH11Y, TMSB4Y, USP9Y, and KDM5D. Three of these changes are missense mutations in genes that produce male-specific minor histocompatibility (H-Y) antigens. Antigens derived from KDM5D, for example, are thought to elicit a maternal immune response during gestation. It is possible that incompatibilities at one or more of these genes played a role in the reproductive isolation of the two groups.

Received: December 22, 2015; Accepted: February 26, 2016; Published: April 7, 2016

© 2016 The Authors. Published by Elsevier Inc.

FREE PDF GRATIS: AJHG

Novos módulos para ensinar medicina evolucionária: uma experiência australiana e suíça

Novel Modules to Teach Evolutionary Medicine: an Australian and a Swiss Experience

Frank Rühli, Martin Haeusler, Arthur Saniotis, Maciej Henneberg

First online: 18 April 2016

DOI: 10.1007/s40670-016-0245-8

Source/Fonte

Abstract

Objectives

Evolutionary medicine is a growing field focusing on the evolutionary basis of human diseases and their changes through time. The introduction of concepts of long- and short-term evolution into the medical curricula is essential to acknowledge the variability of human biology.

Methods

Three courses of the EM taught at the University of Zurich and the University of Adelaide are presented by giving their general descriptions, full curricula, and the results of anonymized student evaluations.

Results

The presented courses meet a growing need and were positively received by the students. Most importantly, they seem to stimulate critical thinking about issues relating to health and evolution.

Conclusions

The incorporation of these topics into curricula will allow future practitioners of health-related professions to apply principles of human evolution and its forces in their work.

Keywords Disease Curricula Evolutionary medicine Medical school

FREE PDF GRATIS: Medical Science Educator

Construção de árvores filogenéticas de alunos de um curso de introdução à biologia

Student construction of phylogenetic trees in an introductory biology course

Jonathan Dees and Jennifer L. Momsen Email author

Evolution: Education and Outreach20169:3

DOI: 10.1186/s12052-016-0054-y© Dees and Momsen. 2016

Received: 25 November 2015Accepted: 14 April 2016Published: 21 April 2016

Source/Fonte

Abstract

Background

Phylogenetic trees have become increasingly essential across biology disciplines. Consequently, learning about phylogenetic trees has become an important component of biology education and an area of interest for biology education research. Construction tasks, in which students generate phylogenetic trees from some type of data, are often used for instruction. However, the impact of these exercises on student learning is uncertain, in part due to our fragmented knowledge of what students construct during the tasks. The goal of this project was to develop a more robust method for describing student-generated phylogenetic trees, which will support future investigations that attempt to link construction tasks with student learning.

Results

Through iterative examination of data from an introductory biology course, we developed a method for describing student-generated phylogenetic trees in terms of style, conventionality, and accuracy. Students used the diagonal style more often than the bracket style for construction tasks. The majority of phylogenetic trees were constructed conventionally, and variable orientation of branches was the most common unconventional feature. In addition, the majority of phylogenetic trees were generated correctly (no errors) or adequately (minor errors only) in terms of accuracy. Suggesting extant taxa are descended from other extant taxa was the most common major error, while empty branches and extra nodes were very common minor errors.

Conclusions

The method we developed to describe student-constructed phylogenetic trees uncovered several trends that warrant further investigation. For example, while diagonal and bracket phylogenetic trees contain equivalent information, student preference for using the diagonal style could impact comprehension. In addition, despite a lack of explicit instruction, students generated phylogenetic trees that were largely conventional and accurate. Surprisingly, accuracy and conventionality were also dependent on each other. Our method for describing phylogenetic trees constructed by students is based on data from one introductory biology course at one institution, and the results are likely limited. We encourage researchers to use our method as a baseline for developing a more generalizable tool, which will support future investigations that attempt to link construction tasks with student learning.

Keywords

Phylogenetic trees Cladograms Conceptual models Construction tasks Evolution Tree thinking

FREE PDF GRATIS: Evo Edu Outreach Sup. Info

Processos não markovianos dificultam o darwinismo quântico

Non-Markovianity hinders Quantum Darwinism

Fernando Galve, Roberta Zambrini & Sabrina Maniscalco

Scientific Reports 6, Article number: 19607 (2016)

doi:10.1038/srep19607

Download Citation

Quantum information Quantum mechanics

Received: 09 October 2015 Accepted: 03 December 2015 Published online: 20 January 2016

Source/Fonte

Abstract

We investigate Quantum Darwinism and the emergence of a classical world from the quantum one in connection with the spectral properties of the environment. We use a microscopic model of quantum environment in which, by changing a simple system parameter, we can modify the information back flow from environment into the system, and therefore its non-Markovian character. We show that the presence of memory effects hinders the emergence of classical objective reality, linking these two apparently unrelated concepts via a unique dynamical feature related to decoherence factors.

FREE PDF GRATIS: Scientific Reports

A fossilização de coração é possível e informa a evolução da via de saída em vertebrados

Tue, 19 Apr 2016

Heart fossilization is possible and informs the evolution of cardiac outflow tract in vertebrates

Lara Maldanis, Murilo Carvalho, Mariana Ramos Almeida, Francisco Idalécio Freitas, José Artur Ferreira Gomes de Andrade, Rafael Silva Nunes, Carlos Eduardo Rochitte, Ronei Jesus Poppi, Raul Oliveira Freitas, Fábio Rodrigues, Sandra Siljeström, Frederico Alves Lima, Douglas Galante, Ismar S Carvalho, Carlos Alberto Perez, Marcelo Rodrigues de Carvalho, Jefferson Bettini, Vincent Fernandez, José Xavier-Neto

PDF Source XML Lens JSON

DOI: 10.7554/eLife.14698

Abstract

Elucidating cardiac evolution has been frustrated by lack of fossils. One celebrated enigma in cardiac evolution involves the transition from a cardiac outflow tract dominated by a multi-valved conus arteriosus in basal actinopterygians, to an outflow tract commanded by the non-valved, elastic, bulbus arteriosus in higher actinopterygians. We demonstrate that cardiac preservation is possible in the extinct fish Rhacolepis buccalis from the Brazilian Cretaceous. Using X-ray synchrotron microtomography, we show that Rhacolepis fossils display hearts with a conus arteriosus containing at least five valve rows. This represents a transitional morphology between the primitive, multivalvar, conal condition and the derived, monovalvar, bulbar state of the outflow tract in modern actinopterygians. Our data rescue a long-lost cardiac phenotype (119-113 Ma) and suggest that outflow tract simplification in actinopterygians is compatible with a gradual, rather than a drastic saltation event. Overall, our results demonstrate the feasibility of studying cardiac evolution in fossils.

DOI: http://dx.doi.org/10.7554/eLife.14698.001

eLife digest

Modern research has majorly advanced our understanding of how the heart works, and has led to new therapies for cardiac diseases. However, little is known about how the heart has evolved throughout the history of animals with backbones – a group that is collectively referred to as vertebrates. This is partly because the heart is made from soft muscle tissue, which does not fossilize as often as harder tissues such as bones.

Even though fossils of soft tissues are rare, paleontologists have already unearthed fossils of other soft organs such as the stomach and umbilical cord. These discoveries suggested that there was hope of finding fossil hearts, and now Maldanis, Carvalho et al. have indeed discovered fossil hearts in two specimens of an extinct species of bony fish called Rhacolepis buccalis. These fish were alive over 113 million years ago during the Cretaceous period, in an area that is now modern-day Brazil.

Like all known vertebrates, these R. buccalis fossils have valves between the heart and the major artery that carries blood out of the heart. Such valves are vital because they prevent pumped blood from flowing back into the heart. However, oddly, R. buccalis fossils show five of these valves, which is more than any advanced bony fish that is alive today. Comparing this with the situation in other fish species suggests that vertebrate hearts gradually evolved to become progressively simpler.

This discovery shows that it is possible to study heart evolution with fossils. Maldanis, Carvalho et al. hope that their findings will stimulate researchers from all over the world to examine the fossils of well-preserved animals in search of clues to help reconstruct the major steps in the evolution of the vertebrate heart.

DOI: http://dx.doi.org/10.7554/eLife.14698.002

FREE PDF GRATIS: eLIFE

+++++

NOTA DESTE BLOGGER:

Uma pesquisa científica importante que tem vários cientistas brasileiros!

Árvore da vida de Darwin em crise! Crise, que crise? Vide!

What Is the Tree of Life?

W. Ford Doolittle , Tyler D. P. Brunet

Published: April 14, 2016http://dx.doi.org/10.1371/journal.pgen.1005912

Source/Fonte

Abstract

A universal Tree of Life (TOL) has long been a goal of molecular phylogeneticists, but reticulation at the level of genes and possibly at the levels of cells and species renders any simple interpretation of such a TOL, especially as applied to prokaryotes, problematic.

Citation: Doolittle WF, Brunet TDP (2016) What Is the Tree of Life? PLoS Genet 12(4): e1005912. doi:10.1371/journal.pgen.1005912

Editor: Susan M. Rosenberg, Baylor College of Medicine, UNITED STATES

Published: April 14, 2016

Copyright: © 2016 Doolittle, Brunet. 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: This work was supported by the Natural Sciences and Engineering Research Council of Canada, grant number GLDSU/447989—2013. The funders had no role in the preparation of the article.

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

FREE PDF GRATIS: PLoS Genetics

Predizendo o comportamento celular através de um modelo matemático

Dynamics of Cell Ensembles on Adhesive Micropatterns: Bridging the Gap between Single Cell Spreading and Collective Cell Migration

Philipp J. Albert, Ulrich S. Schwarz 

Published: April 7, 2016 http://dx.doi.org/10.1371/journal.pcbi.1004863

Source/Fonte

Abstract

The collective dynamics of multicellular systems arise from the interplay of a few fundamental elements: growth, division and apoptosis of single cells; their mechanical and adhesive interactions with neighboring cells and the extracellular matrix; and the tendency of polarized cells to move. Micropatterned substrates are increasingly used to dissect the relative roles of these fundamental processes and to control the resulting dynamics. Here we show that a unifying computational framework based on the cellular Potts model can describe the experimentally observed cell dynamics over all relevant length scales. For single cells, the model correctly predicts the statistical distribution of the orientation of the cell division axis as well as the final organisation of the two daughters on a large range of micropatterns, including those situations in which a stable configuration is not achieved and rotation ensues. Large ensembles migrating in heterogeneous environments form non-adhesive regions of inward-curved arcs like in epithelial bridge formation. Collective migration leads to swirl formation with variations in cell area as observed experimentally. In each case, we also use our model to predict cell dynamics on patterns that have not been studied before.

Author Summary

The collective dynamics of many cells is more than the sum of its parts. For example, large cell collectives often form streams, swirls or bridges that cannot be achieved by single cells. Yet the dynamic processes of single cells, especially their response to adhesive and mechanical cues, stays an essential element of the collective cell dynamics. Here we introduce a comprehensive modeling framework that allows us to predict cellular dynamics from the level of single cells up to the level of large cell collectives on the same footing. We focus on cellular dynamics on adhesive micropatterns as an especially successful approach to investigate and control complex cell behaviour. Our model successfully predicts a large range of experimentally observed phenomena, allows us to investigate the relative importance of the different cellular processes and in the future can be used to design new adhesive micropatterns that promote desired cell dynamics.

Citation: Albert PJ, Schwarz US (2016) Dynamics of Cell Ensembles on Adhesive Micropatterns: Bridging the Gap between Single Cell Spreading and Collective Cell Migration. PLoS Comput Biol 12(4): e1004863. doi:10.1371/journal.pcbi.1004863

Editor: Feilim Mac Gabhann, Johns Hopkins University, UNITED STATES

Received: August 31, 2015; Accepted: March 11, 2016; Published: April 7, 2016

Copyright: © 2016 Albert, Schwarz. 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.

Data Availability: All relevant data are within the paper and its Supporting Information files.

Funding: This work was supported by the European Union’s Seventh Framework Programme through the MEHTRICS-project (Micropattern Enhanced High Throughput RNA Interference for Cell Screening, http://www.mehtrics.com, grant agreement 278758). We also acknowledge support by the EcTop B programme (cytoskeleton) of the cluster of excellence CellNetworks. 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.

FREE PDF GRATIS: PLoS Computational Biology

Rota dinâmica de informação em redes complexas: mero acaso, fortuita necessidade ou design inteligente?

Dynamic information routing in complex networks

Christoph Kirst, Marc Timme & Demian Battaglia 

Affiliations Contributions Corresponding author

Nature Communications 7, Article number: 11061 doi:10.1038/ncomms11061 

Received 01 December 2015 Accepted 16 February 2016 Published 12 April 2016

Source/Fonte: Nature Reviews Genetics 

Abstract 

Flexible information routing fundamentally underlies the function of many biological and artificial networks. Yet, how such systems may specifically communicate and dynamically route information is not well understood. Here we identify a generic mechanism to route information on top of collective dynamical reference states in complex networks. Switching between collective dynamics induces flexible reorganization of information sharing and routing patterns, as quantified by delayed mutual information and transfer entropy measures between activities of a network’s units. We demonstrate the power of this mechanism specifically for oscillatory dynamics and analyse how individual unit properties, the network topology and external inputs co-act to systematically organize information routing. For multi-scale, modular architectures, we resolve routing patterns at all levels. Interestingly, local interventions within one sub-network may remotely determine nonlocal network-wide communication. These results help understanding and designing information routing patterns across systems where collective dynamics co-occurs with a communication function.

Subject terms: Physical sciences Theoretical physics

FREE PDF GRATIS: Nature Communications

Cientistas descobrem os segredos da "bússola" das borboletas Monarcas

Neural Integration Underlying a Time-Compensated Sun Compass in the Migratory Monarch Butterfly

Eli Shlizerman, James Phillips-Portillo, Daniel B. Forgercorrespondenceemail, Steven M. Reppert

Publication stage: In Press Corrected Proof

Open Access

DOI: http://dx.doi.org/10.1016/j.celrep.2016.03.057

Highlights

• A model for time-compensated sun compass used by monarch butterflies is developed

• Neural oscillations encoding solar azimuth and time of day are proposed

• Special integration of neural oscillations enables correction to southwest flight

• The model explains flight simulator tracks and supports northeast remigration

Summary

Migrating eastern North American monarch butterflies use a time-compensated sun compass to adjust their flight to the southwest direction. Although the antennal genetic circadian clock and the azimuth of the sun are instrumental for proper function of the compass, it is unclear how these signals are represented on a neuronal level and how they are integrated to produce flight control. To address these questions, we constructed a receptive field model of the compound eye that encodes the solar azimuth. We then derived a neural circuit model that integrates azimuthal and circadian signals to correct flight direction. The model demonstrates an integration mechanism, which produces robust trajectories reaching the southwest regardless of the time of day and includes a configuration for remigration. Comparison of model simulations with flight trajectories of butterflies in a flight simulator shows analogous behaviors and affirms the prediction that midday is the optimal time for migratory flight.

Received: September 2, 2015; Received in revised form: February 11, 2016; Accepted: March 15, 2016; Published: April 14, 2016

© 2016 The Authors. Published by Elsevier Inc.

FREE PDF GRATIS: Cell Reports