Paleontólogos propõem nova teoria da evolução dos cavalos

The evolution and anatomy of the horse manus with an emphasis on digit reduction

Nikos Solounias, Melinda Danowitz, Elizabeth Stachtiaris, Abhilasha Khurana, Marwan Araim, Marc Sayegh, Jessica Natale

Published 24 January 2018.DOI: 10.1098/rsos.171782

Abstract

We revisit digit reduction in the horse and propose that all five digits are partially present in the modern adult forelimb. Osteological descriptions of selected tetradactyl, tridactyl and monodactyl equids demonstrate the evolution of the forelimb. Histological, osteological and palaeontological evidence suggest that the Equus distal forelimb is more complex than traditionally conceived. The current understanding is that the horse distal forelimb consists of one complete digit (III) and two reduced splint metacarpals (II and IV). Metacarpals II and IV each exhibit a ventral ridge, which we suggest represents the undifferentiated digits I and V. These ridges are present in the tridactyl Mesohippus, but are absent in the tetradactyl Hyracotherium. The carpal articulations of the five metacarpals match those of pentadactyl taxa. Distally, the frog, a V-shaped structure on the ventral hoof represents digits II and IV, and the wings and hoof cartilages of the distal phalanx are digits I and V. We relate this revised interpretation of the Equus forelimb to Laetoli footprints, and suggest the Hipparion side impressions are created from the hooves of I and V, rather than from II and IV. We show shades of pentadactyly within the Equus manus.

FREE PDF GRATIS: R. Soc. open sci

Além da falseabilidade: a ciência normal em um multiverso. Pode isso, Arnaldo?

Beyond Falsifiability: Normal Science in a Multiverse

Sean M. Carroll

(Submitted on 15 Jan 2018)

Source/Fonte: YouTube

Cosmological models that invoke a multiverse - a collection of unobservable regions of space where conditions are very different from the region around us - are controversial, on the grounds that unobservable phenomena shouldn't play a crucial role in legitimate scientific theories. I argue that the way we evaluate multiverse models is precisely the same as the way we evaluate any other models, on the basis of abduction, Bayesian inference, and empirical success. There is no scientifically respectable way to do cosmology without taking into account different possibilities for what the universe might be like outside our horizon. Multiverse theories are utterly conventionally scientific, even if evaluating them can be difficult in practice.

Comments: Invited contribution to "Epistemology of Fundamental Physics: Why Trust a Theory?", eds. R. Dawid, R. Dardashti, and K. Th\'ebault (Cambridge University Press)
Subjects: History and Philosophy of Physics (physics.hist-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
Report number: CALT 2018-003
Cite as: arXiv:1801.05016 [physics.hist-ph]
(or arXiv:1801.05016v1 [physics.hist-ph] for this version)

FREE PDF GRATIS: arXiv


Submission history From: Sean Carroll [view email]
[v1] Mon, 15 Jan 2018 21:13:54 GMT (17kb)

Clonagem de macacos através de transferência nuclear de células somáticas - clonagem humana à vista?

Cloning of Macaque Monkeys by Somatic Cell Nuclear Transfer

Zhen Liu, Yijun Cai, Yan Wang, Yanhong Nie, Chenchen Zhang, Yuting Xu, Xiaotong Zhang, Yong Lu, Zhanyang Wang, Muming Poo, Qiang Sun 

Correspondence

Corresponding author2, Qiang Sun
2Lead Contact

Published: January 24, 2018
Publication stage: In Press Corrected Proof

Cloning of Macaque Monkeys by Somatic Cell Nuclear Transfer
DOI: http://dx.doi.org/10.1016/j.cell.2018.01.020

Article Info

Publication History
Published: January 24, 2018 Accepted: January 16, 2018; Received in revised form: January 11, 2018; Received: December 21, 2017

Highlights

• •
  Somatic cell nuclear transfer (SCNT) using fetal fibroblasts yielded two live monkeys
• •
  Epigenetic modulators promoted development and pregnancy rate of SCNT embryos
• •
  SCNT using adult cumulus cells yielded live births of monkeys that were short-lived
• •
  Genetic analysis confirmed the clonal origin of the SCNT monkey offspring

Summary

Generation of genetically uniform non-human primates may help to establish animal models for primate biology and biomedical research. In this study, we have successfully cloned cynomolgus monkeys (Macaca fascicularis) by somatic cell nuclear transfer (SCNT). We found that injection of H3K9me3 demethylase Kdm4d mRNA and treatment with histone deacetylase inhibitor trichostatin A at one-cell stage following SCNT greatly improved blastocyst development and pregnancy rate of transplanted SCNT embryos in surrogate monkeys. For SCNT using fetal monkey fibroblasts, 6 pregnancies were confirmed in 21 surrogates and yielded 2 healthy babies. For SCNT using adult monkey cumulus cells, 22 pregnancies were confirmed in 42 surrogates and yielded 2 babies that were short-lived. In both cases, genetic analyses confirmed that the nuclear DNA and mitochondria DNA of the monkey offspring originated from the nucleus donor cell and the oocyte donor monkey, respectively. Thus, cloning macaque monkeys by SCNT is feasible using fetal fibroblasts.

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Biometria quântica explora a capacidade do olho humano detectar prótons: mero acaso, fortuita necessidade ou design inteligente?

Quantum Biometrics with Retinal Photon Counting

M. Loulakis, G. Blatsios, C. S. Vrettou, I. K. Kominis

Source/Fonte: Salvo

(Submitted on 14 Apr 2017 (v1), last revised 26 Oct 2017 (this version, v2))

It is known that the eye's scotopic photodetectors, rhodopsin molecules and their associated phototransduction mechanism leading to light perception, are efficient single photon counters. We here use the photon counting principles of human rod vision to propose a secure quantum biometric identification based on the quantum-statistical properties of retinal photon detection. The photon path along the human eye until its detection by rod cells is modeled as a filter having a specific transmission coefficient. Precisely determining its value from the photodetection statistics registered by the conscious observer is a quantum parameter estimation problem that leads to a quantum secure identification method. The probabilities for false positive and false negative identification of this biometric technique can readily approach 10−10 and 10−4, respectively. The security of the biometric method can be further quantified by the physics of quantum measurements. An impostor must be able to perform quantum thermometry and quantum magnetometry with energy resolution better than 10−9ℏ, in order to foil the device by non-invasively monitoring the biometric activity of a user.

Comments:	16 pages, 4 figures
Subjects:	Quantum Physics (quant-ph); Probability (math.PR); Biological Physics (physics.bio-ph); Computational Physics (physics.comp-ph); Optics (physics.optics)
Journal reference:	Phys. Rev. Applied 8, 044012 (2017)
DOI:	10.1103/PhysRevApplied.8.044012
Cite as:	arXiv:1704.04367 [quant-ph]
	(or arXiv:1704.04367v2 [quant-ph] for this version)

Submission history

From: Iannis Kominis [view email]
[v1] Fri, 14 Apr 2017 07:11:37 GMT (3822kb)
[v2] Thu, 26 Oct 2017 11:52:22 GMT (4129kb)

FREE PDF GRATIS: arXiv

A evolução pulsada modelou os tamanhos corporais de vertebrados modernos

Pulsed evolution shaped modern vertebrate body sizes

Michael J. Landis a and Joshua G. Schraiber b,c,1

Author Affiliations

a Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT 06520;

b Department of Biology, Temple University, Philadelphia, PA 19122;

c Institute for Genomics and Evolutionary Medicine, Temple University, Philadelphia, PA 19122

Edited by Neil H. Shubin, The University of Chicago, Chicago, IL, and approved October 6, 2017 (received for review June 18, 2017)

Significance

The diversity of forms found among animals on Earth is striking. Despite decades of study, it has been difficult to reconcile the patterns of diversity seen between closely related species with those observed when studying single species on ecological timescales. We propose a set of models, called Lévy processes, to attempt to reconcile rapid evolution between species with the relatively stable distributions of phenotypes seen within species. These models, which have been successfully used to model stock market data, allow for long periods of stasis followed by bursts of rapid change. We find that many vertebrate groups are well fitted by Lévy models compared with models for which traits evolve toward a stationary optimum or evolve in an incremental and wandering manner.

Abstract

The relative importance of different modes of evolution in shaping phenotypic diversity remains a hotly debated question. Fossil data suggest that stasis may be a common mode of evolution, while modern data suggest some lineages experience very fast rates of evolution. One way to reconcile these observations is to imagine that evolution proceeds in pulses, rather than in increments, on geological timescales. To test this hypothesis, we developed a maximum-likelihood framework for fitting Lévy processes to comparative morphological data. This class of stochastic processes includes both an incremental and a pulsed component. We found that a plurality of modern vertebrate clades examined are best fitted by pulsed processes over models of incremental change, stationarity, and adaptive radiation. When we compare our results to theoretical expectations of the rate and speed of regime shifts for models that detail fitness landscape dynamics, we find that our quantitative results are broadly compatible with both microevolutionary models and observations from the fossil record.

macroevolution Levy process pulsed evolution adaptive landscape

Footnotes

1To whom correspondence should be addressed. Email: joshua.schraiber@temple.edu.

Author contributions: M.J.L. and J.G.S. designed research, performed research, analyzed data, and wrote the paper.

The authors declare no conflict of interest.

This article is a PNAS Direct Submission.

See Commentary on page 13068.

This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1710920114/-/DCSupplemental. 

This open access article is distributed under Creative Commons Attribution-NonCommercial-NoDerivatives License 4.0 (CC BY-NC-ND).

FREE PDF GRATIS: PNAS

Estigmatização e validação do ateísmo, literalismo, e não literalismo no discurso sobre a teoria evolucionária

Secularism and Nonreligion
Research Article

Stigmatization and Validation of Atheism, Literalism, and Non-Literalism in the Discourse over Evolutionary Theory

Author: Eric O. Silva

Source/Fonte

Abstract

This article explores how atheism, literalism, and non-literalism are validated and stigmatized in public discourse over evolutionary theory. Through an ethnographic content analysis of 1,028 letters to the editor, I examine how authors frame the relationship between acceptance of evolutionary theory and religious faith. I find there are four ways of doing so: 1) implicit polarization, obliquely denies any compatibility between religion and evolution; 2) distancing, separates one’s position from that of another; 3) articulation, weaves evolution and faith together; and 4) combinations of polarization, distancing, and articulation. Each framing results in some mixture of stigmatization and validation of atheism, literalism, and non-literalism. Implicit polarization stigmatizes and validates atheism and literalism. Implicit polarization stigmatizes non-literalism through unacknowledgment. Distancing can validate and stigmatize literalism and non-literalism, while it also results in literalism and atheism being stigmatized by putative allies. Articulation validates non-literalism by representing it in the public sphere and it stigmatizes atheism and literalism through unacknowledgment.

How to Cite: Silva, E.O., (2018). Stigmatization and Validation of Atheism, Literalism, and Non-Literalism in the Discourse over Evolutionary Theory. Secularism and Nonreligion. 7(1), p.1. DOI: http://doi.org/10.5334/snr.44

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Uma hipótese concernente o estabelecimento do endosimbionte protomitocondrial durante a eucariogênese

Journal of Molecular Evolution

October 2017, Volume 85, Issue 3–4, pp 99–106 | Cite as

Some Liked It Hot: A Hypothesis Regarding Establishment of the Proto-Mitochondrial Endosymbiont During Eukaryogenesis

Authors

Cory D. Dunn 1, 2

1. Email author View author's OrcID profile

1.Institute of Biotechnology, Helsinki Institute of Life Science University of Helsinki Finland

2.College of Sciences Koç University Sarıyer Turkey

Open Access Original Article

First Online: 15 September 2017

Abstract

Eukaryotic cells are characterized by a considerable increase in subcellular compartmentalization when compared to prokaryotes. Most evidence suggests that the earliest eukaryotes consisted of mitochondria derived from an α-proteobacterial ancestor enclosed within an archaeal host cell. However, what benefits the archaeal host and the proto-mitochondrial endosymbiont might have obtained at the beginning of this endosymbiotic relationship remains unclear. In this work, I argue that heat generated by the proto-mitochondrion initially permitted an archaeon living at high temperatures to colonize a cooler environment, thereby removing apparent limitations on cellular complexity. Furthermore, heat generation by the endosymbiont would have provided phenotypic flexibility not available through fixed alleles selected for fitness at specific temperatures. Finally, a role for heat production by the proto-mitochondrion bridges a conceptual gap between initial endosymbiont entry to the archaeal host and a later role for mitochondrial ATP production in permitting increased cellular complexity.

Keywords Endosymbiosis Eukaryogenesis Mitochondria Archaea Temperature Bioenergetics

FREE PDF GRATIS: Journal of Molecular Evolution

Calculando o tempo para o ancestral comum de um alelo benéfico

Estimating time to the common ancestor for a beneficial allele

Joel Smith Graham Coop Matthew Stephens John Novembre

Molecular Biology and Evolution, msy006,

https://doi.org/10.1093/molbev/msy006

Published: 18 January 2018

Article history

Received: 10 August 2017 Revision Received: 02 January 2018

Accepted: 13 January 2018

Source/Fonte

Abstract

The haplotypes of a beneficial allele carry information about its history that can shed light on its age and the putative cause for its increase in frequency. Specifically, the signature of an allele’s age is contained in the pattern of variation that mutation and recombination impose on its haplotypic background. We provide a method to exploit this pattern and infer the time to the common ancestor of a positively selected allele following a rapid increase in frequency. We do so using a hidden Markov model which leverages the length distribution of the shared ancestral haplotype, the accumulation of derived mutations on the ancestral background, and the surrounding background haplotype diversity. Using simulations, we demonstrate how the inclusion of information from both mutation and recombination events increases accuracy relative to approaches that only consider a single type of event. We also show the behavior of the estimator in cases where data do not conform to model assumptions, and provide some diagnostics for assessing and improving inference. Using the method, we analyze population-specific patterns in the 1000 Genomes Project data to estimate the timing of adaptation for several variants which show evidence of recent selection and functional relevance to diet, skin pigmentation, and morphology in humans.

Issue Section: Article

© The Author(s) 2018. 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: Molecular Biology Evolution

Empacotando um genoma passo a passo: mero acaso, fortuita necessidade ou design inteligente?

A pathway for mitotic chromosome formation

Johan H. Gibcus1,*, Kumiko Samejima2,*, Anton Goloborodko3,*, Itaru Samejima2, Natalia Naumova1, Johannes Nuebler3, Masato T. Kanemaki4, Linfeng Xie5, James R. Paulson5, William C. Earnshaw2,†, Leonid A. Mirny3,†, Job Dekker1,6,†

1Program in Systems Biology, Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, 368 Plantation Street, Worcester, MA 01605, USA.

2Wellcome Centre for Cell Biology University of Edinburgh, King’s Buildings, Max Born Crescent Edinburgh EH9 3BF, Scotland, UK.

3Institute for Medical Engineering and Science, and Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.

4Division of Molecular Cell Engineering, National Institute of Genetics, Research Organization of Information and Systems (ROIS), and Department of Genetics, SOKENDAI, Yata 1111, Mishima, Shizuoka 411-8540, Japan.

5Department of Chemistry, University of Wisconsin-Oshkosh, 800 Algoma Blvd, Oshkosh, WI 54901, USA.

6Howard Hughes Medical Institute, 4000 Jones Bridge Road, Chevy Chase, MD 20815-6789, USA.

↵†Corresponding author. Email: bill.earnshaw@ed.ac.uk (W.C.E.); leonid@MIT.edu (L.A.M.); job.dekker@umassmed.edu (J.D.)

↵* These authors contributed equally to this work.

Hide authors and affiliations

Science  18 Jan 2018:

eaao6135

DOI: 10.1126/science.aao6135

Source/Fonte: Anton Goloborodko

Abstract

Mitotic chromosomes fold as compact arrays of chromatin loops. To identify the pathway of mitotic chromosome formation, we combined imaging and Hi-C of synchronous DT40 cell cultures with polymer simulations. We show that in prophase, the interphase organization is rapidly lost in a condensin-dependent manner and arrays of consecutive 60 kb loops are formed. During prometaphase ~80 kb inner loops are nested within ~400 kb outer loops. The loop array acquires a helical arrangement with consecutive loops emanating from a central spiral-staircase condensin scaffold. The size of helical turns progressively increases during prometaphase to ~12 Mb. Acute depletion of condensin I or II shows that nested loops form by differential action of the two condensins while condensin II is required for helical winding.

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Origem da vida: a emergência espontânea de auto replicação em sistemas de reação química

Spontaneous emergence of self-replication in chemical reaction systems

Yu Liu, David Sumpter

(Submitted on 17 Jan 2018)

Source/Fonte: Ruhr-Universität Bochum

Explaining the origin of life requires us to explain how self-replication arises. To be specific, how can a self-replicating entity develop spontaneously from a chemical reaction system in which no reaction is self-replicating? Previously proposed mathematical models either supply an explicit framework for a minimal living system or only consider catalyzed reactions, and thus fail to provide a comprehensive theory. We set up a general model for chemical reaction systems that properly accounts for energetics, kinetics and the conservation law. We find that (1) some systems are collectively-catalytic where reactants are transformed into end products with the assistance of intermediates (as in the citric acid cycle), while some others are self-replicating where different parts replicate each other and the system self-replicates as a whole (as in the formose reaction); (2) many alternative chemical universes often contain one or more such systems; (3) it is possible to construct a self-replicating system where the entropy of some parts spontaneously decreases, in a manner similar to that discussed by Schrodinger; (4) complex self-replicating molecules can emerge spontaneously and relatively easily from simple chemical reaction systems through a sequence of transitions. Together these results start to explain the origins of prebiotic evolution.

Comments:	Supplementary Information (SI) attached. To view SI, please download and extract the zipped file listed under "Other formats"
Subjects:	Adaptation and Self-Organizing Systems (nlin.AO); Molecular Networks (q-bio.MN)
Cite as:	arXiv:1801.05872 [nlin.AO]
	(or arXiv:1801.05872v1 [nlin.AO] for this version)

Submission history

From: Yu Liu [view email]
[v1] Wed, 17 Jan 2018 22:02:44 GMT (712kb,A)

FREE PDF GRATIS: ArXiv