A origem e a evolução dinâmica da transferência de informação química

The origin and dynamic evolution of chemical information transfer

Sandra Steiger1,*, Thomas Schmitt2 and H. Martin Schaefer2

+Author Affiliations

1School of Biological Sciences, Behavior, Ecology, Evolution and Systematics Section, Illinois State University, Normal Il61790-4120, USA

2Faculty of Biology, Department of Evolutionary Biology and Animal Ecology, University of Freiburg, Hauptstrasse 1, 79104 Freiburg, Germany

* Author for correspondence (ssteige@ilstu.edu).

Abstract

Although chemical communication is the most widespread form of communication, its evolution and diversity are not well understood. By integrating studies of a wide range of terrestrial plants and animals, we show that many chemicals are emitted, which can unintentionally provide information (cues) and, therefore, act as direct precursors for the evolution of intentional communication (signals). Depending on the content, design and the original function of the cue, there are predictable ways that selection can enhance the communicative function of chemicals. We review recent progress on how efficacy-based selection by receivers leads to distinct evolutionary trajectories of chemical communication. Because the original function of a cue may channel but also constrain the evolution of functional communication, we show that a broad perspective on multiple selective pressures acting upon chemicals provides important insights into the origin and dynamic evolution of chemical information transfer. Finally, we argue that integrating chemical ecology into communication theory may significantly enhance our understanding of the evolution, the design and the content of signals in general.

chemical communication, signal, cue, volatiles, evolution of communication, pheromone

Received October 20, 2010.

Accepted November 26, 2010.

This Journal is © 2010 The Royal Society

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Novo sítio de fósseis na China revela a longa recuperação da vida da maior extinção na história da Terra

New Fossil Site in China Shows Long Recovery of Life from the Largest Extinction in Earth's History

ScienceDaily (Dec. 23, 2010) — A major new fossil site in south-west China has filled in a sizeable gap in our understanding of how life on this planet recovered from the greatest mass extinction of all time, according to a paper co-authored by Professor Mike Benton, in the School of Earth Sciences, and published in the Proceedings of the Royal Society B. The work is led by scientists from the Chengdu Geological Center in China.

An ichthyosaur, a one-meter long fish-eating reptile -- from the new fossil site in China. (Credit: Image courtesy of University of Bristol)

Some 250 million years ago, at the end of the time known as the Permian, life was all but wiped out during a sustained period of massive volcanic eruption and devastating global warming. Only one in ten species survived, and these formed the basis for the recovery of life in the subsequent time period, called the Triassic. The new fossil site -- at Luoping in Yunnan Province -- provides a new window on that recovery, and indicates that it took about 10 million years for a fully-functioning ecosystem to develop.

"The Luoping site dates from the Middle Triassic and contains one of the most diverse marine fossil records in the world," said Professor Benton. "It has yielded 20,000 fossils of fishes, reptiles, shellfish, shrimps and other seabed creatures. We can tell that we're looking at a fully recovered ecosystem because of the diversity of predators, most notably fish and reptiles. It's a much greater diversity than what we see in the Early Triassic -- and it's close to pre-extinction levels."

Reinforcing this conclusion is the complexity of the food web, with the bottom of the food chains dominated by species typical of later Triassic marine faunas -- such as crustaceans, fishes and bivalves -- and different from preceding ones.

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Proceedings of the Royal Society B

The Luoping biota: exceptional preservation, and new evidence on the Triassic recovery from end-Permian mass extinction

Shi-xue Hu1, Qi-yue Zhang1, Zhong-Qiang Chen2, Chang-yong Zhou1, Tao Lü1, 

Tao Xie1, Wen Wen1, Jin-yuan Huang1 and Michael J. Benton3,*

+Author Affiliations

1Chengdu Institute of Geology and Mineral Resources, Chengdu 610081, China

2School of Earth and Environment, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia

3School of Earth Sciences, University of Bristol, Bristol BS8 1RJ, UK

* Author for correspondence (mike.benton@bristol.ac.uk).

Abstract

The timing and nature of biotic recovery from the devastating end-Permian mass extinction (252 Ma) are much debated. New studies in South China suggest that complex marine ecosystems did not become re-established until the middle–late Anisian (Middle Triassic), much later than had been proposed by some. The recently discovered exceptionally preserved Luoping biota from the Anisian Stage of the Middle Triassic, Yunnan Province and southwest China shows this final stage of community assembly on the continental shelf. The fossil assemblage is a mixture of marine animals, including abundant lightly sclerotized arthropods, associated with fishes, marine reptiles, bivalves, gastropods, belemnoids, ammonoids, echinoderms, brachiopods, conodonts and foraminifers, as well as plants and rare arthropods from nearby land. In some ways, the Luoping biota rebuilt the framework of the pre-extinction latest Permian marine ecosystem, but it differed too in profound ways. New trophic levels were introduced, most notably among top predators in the form of the diverse marine reptiles that had no evident analogues in the Late Permian. The Luoping biota is one of the most diverse Triassic marine fossil Lagerstätten in the world, providing a new and early window on recovery and radiation of Triassic marine ecosystems some 10 Myr after the end-Permian mass extinction.

end-Permian mass extinction, Triassic recovery, Luoping, China, marine reptiles

Received October 18, 2010.

Accepted November 30, 2010.

This Journal is © 2010 The Royal Society

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Gene de reversão sexual (?): camundongos machos podem ser criados sem o cromossomo Y através de antigo gene do cérebro

Sex Reversal Gene: Male Mice Can Be Created Without Y Chromosome Via Ancient Brain Gene

ScienceDaily (Dec. 22, 2010) — Researchers in Australia are a step closer to unraveling the mysteries of human sexual development, following genetic studies that show male mice can be created without a Y chromosome -- through the activation of an ancient brain gene.

This is a mouse from associate professor Paul Thomas' lab. Associate professor Thomas and his colleagues have generated male mice with two X chromosomes by artificially activating the SOX3 gene in the developing gonads. (Credit: Photo bySandra Piltz / © University of Adelaide)

Males usually have one Y chromosome and one X chromosome, while females have two X chromosomes. A single gene on the Y, called SRY, triggers testes development in the early embryo, and once these begin to form, the rest of the embryo also becomes male.

However, Adelaide researchers have discovered a way of creating a male mouse without a Y chromosome by activating a single gene, called SOX3, in the developing fetus. SOX3 is known to be important for brain development but has not previously been shown to be capable of triggering the male pathway.

In a major international collaborative study, they also have shown for the first time that changes in the human version of the same gene are present in some patients with disorders of sexual development.

The results of this work are published online in the Journal of Clinical Investigation, and will be published in the journal's print version in January 2011.

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Identification of SOX3 as an XX male sex reversal gene in mice and humans

Edwina Sutton1, James Hughes1, Stefan White2, Ryohei Sekido3, Jacqueline Tan2, Valerie Arboleda4,Nicholas Rogers1, Kevin Knower5, Lynn Rowley2, Helen Eyre6, Karine Rizzoti3, Dale McAninch1,Joao Goncalves7, Jennie Slee8, Erin Turbitt2, Damien Bruno2, Henrik Bengtsson9, Vincent Harley5,Eric Vilain4, Andrew Sinclair2, Robin Lovell-Badge3 and Paul Thomas1

1School of Molecular and Biomedical Science and Australian Research Council Special Research Centre for the Molecular Genetics of Development, University of Adelaide, Adelaide, South Australia, Australia. 

2Murdoch Children’s Research Institute and Department of Paediatrics, University of Melbourne, Royal Children’s Hospital, Melbourne, Victoria, Australia. 

3Division of Developmental Genetics, MRC National Institute for Medical Research, London, United Kingdom. 

4Department of Human Genetics, David Geffen School of Medicine, UCLA, Los Angeles, California USA. 

5Prince Henry’s Institute of Medical Research, Melbourne, Victoria, Australia. 

6Women’s and Children’s Hospital, North Adelaide, South Australia, Australia. 

7Centro de Genética Humana, Instituto Nacional de Saúde Dr Ricardo Jorge, Lisbon, Portugal. 

8Genetic Services of Western Australia, King Edward Memorial Hospital, Subiaco, Western Australia, Australia. 

9Department of Statistics, University of California, Berkeley, California, USA.

Address correspondence to: Paul Thomas, Level 3, Molecular Life Sciences Building, University of Adelaide, North Terrace, Adelaide, South Australia, 5005 Australia. Phone: 61.8.8303.7047; Fax: 61.8.8303.4362; E-mail: paul.thomas@adelaide.edu.au.

Published December 22, 2010

Received for publication February 8, 2010, and accepted in revised form October 27, 2010.

Sex in mammals is genetically determined and is defined at the cellular level by sex chromosome complement (XY males and XX females). The Y chromosome–linked gene sex-determining region Y (SRY) is believed to be the master initiator of male sex determination in almost all eutherian and metatherian mammals, functioning to upregulate expression of its direct target gene Sry-related HMG box–containing gene 9 (SOX9). Data suggest that SRY evolved from SOX3, although there is no direct functional evidence to support this hypothesis. Indeed, loss-of-function mutations in SOX3 do not affect sex determination in mice or humans. To further investigate Sox3 function in vivo, we generated transgenic mice overexpressing Sox3. Here, we report that in one of these transgenic lines, Sox3 was ectopically expressed in the bipotential gonad and that this led to frequent complete XX male sex reversal. Further analysis indicated that Sox3 induced testis differentiation in this particular line of mice by upregulating expression of Sox9 via a similar mechanism to Sry. Importantly, we also identified genomic rearrangements within the SOX3 regulatory region in three patients with XX male sex reversal. Together, these data suggest that SOX3 and SRY are functionally interchangeable in sex determination and support the notion that SRY evolved from SOX3 via a regulatory mutation that led to its de novo expression in the early gonad.

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FREE PDF GRÁTIS

Um show fotográfico 100% Design Inteligente

Hippocampus

by Tamily Weissman, Harvard University

"Brainbow" mice are engineered with a gene that includes three different fluorescent proteins, but only one color is actually expressed from each copy of the DNA construct. Pairs of "incompatible lox sites" are nested around different portions of the gene, allowing for recombination to snip out different parts of the gene randomly. Depending on what DNA is excised, a different color results.

Image: The hippocampus is the key memory-forming center of the brain and displays high rates of neurogenesis even in adults. Here individual neurons of the dentate gyrus, a layer of the hippocampus, project their dendrites to the outer layer, where they receive input from the cortex. Neurogenesis occurs inside the "V," where neurons are born and then migrate outward toward the dentate gryus.

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See more pictures here/Veja mais fotos aqui: Cell

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NOTA DESTE BLOGGER:

As descobertas extraordinárias que a ciência descobre a cada dia mostra, nível após nível, cada vez mais complexidade sobre complexidade que o mero acaso, a fortuita necessidade através da seleção natural ao longo de milhões, bilhões de anos, se mostram heuristicamente impotentes de explicar isso no contexto de justificação teórica.

Fui, nem sei por que, pensando, por que a maioria dos cientistas não consegue ver sinais de inteligência empiricamente detectados nesses níveis de complexidade das formas biológicas? Por que outros cientistas conseguem ver? Questão de Weltanschauungen???

A maioria do total de RNA não ribosômico codificado no núcleo em uma célula humana é 'matéria escura' de RNA não anotado

The majority of total nuclear-encoded non-ribosomal RNA in a human cell is 'dark matter' un-annotated RNA

Philipp Kapranov , Georges St. Laurent , Tal Raz , Fatih Ozsolak , C. PATRICK Reynolds , Poul HB Sorensen , Gregory Reaman , Patrice Milos , Robert J Arceci , John F Thompson and Timothy J Triche 

BMC Biology 2010, 8:149doi:10.1186/1741-7007-8-149

Published: 21 December 2010

Abstract (provisional)

Background

Discovery that the transcriptional output of the human genome is far more complex than predicted by the current set of protein-coding annotations and that most RNAs produced do not appear to encode proteins has transformed our understanding of genome complexity and suggests new paradigms of genome regulation. However, the fraction of all cellular RNA whose function we do not understand and the fraction of the genome that is utilized to produce that RNA remain controversial. This is not simply a bookkeeping issue because the degree to which this un-annotated transcription is present has important implications with respect to its biologic function and to the general architecture of genome regulation. For example, efforts to elucidate how non-coding RNAs (ncRNAs) regulate genome function will be compromised if that class of RNAs is dismissed as simply 'transcriptional noise'.

Results

We show that the relative mass of RNA whose function and/or structure we do not understand (the so called 'dark matter' RNAs), as a proportion of all non-ribosomal, non-mitochondrial human RNA (mt-RNA), can be greater than that of protein-encoding transcripts. This observation is obscured in studies that focus only on polyA-selected RNA, a method that enriches for protein coding RNAs and at the same time discards the vast majority of RNA prior to analysis. We further show the presence of a large number of very long, abundantly-transcribed regions (100's of kb) in intergenic space and further show that expression of these regions is associated with neoplastic transformation. These overlap some regions found previously in normal human embryonic tissues and raises an interesting hypothesis as to the function of these ncRNAs in both early development and neoplastic transformation.

Conclusions

We conclude that 'dark matter' RNA can constitute the majority of non-ribosomal, non-mitochondrial-RNA and a significant fraction arises from numerous very long, intergenic transcribed regions that could be involved in neoplastic transformation.

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FREE PDF GRÁTIS [OPEN ACCESS] 586 KB

Scientist Uncovers Switch Controlling Protein Production

ScienceDaily (Dec. 22, 2010) — A scientist from the Florida campus of The Scripps Research Institute has discovered a molecular switch that controls the synthesis of ribosomes. Ribosomes are the large machineries inside all living cells that produce proteins, the basic working units of any cell. These new findings offer a novel target for potential treatments for a range of diseases, including cancer.

The study is published in the December 24, 2010 edition of theJournal of Molecular Biology.

The study identified the molecular switch, essentially formed by a small sequence of RNA, that controls a critical part of ribosome synthesis to allow for strict, albeit temporary, regulation of the process.

"These kinds of switches in RNA are thought to be slow acting," said Katrin Karbstein, an assistant professor in the Department of Cancer Biology at Scripps Florida who helped lead the study. "That suggests a point where we might intervene to modify the process -- then you could potentially shut down the pathway, because if you don't produce ribosomes, you cannot make proteins. Thus, cells can't grow. That would be a desirable outcome in cancer, for example."

This slowness may be there precisely so these regulatory points can be introduced for cells to downregulate growth when nutrition is scarce.

"Perhaps, nature has found a way to exploit RNA's Achilles' heel -- its propensity to form alternative structures that can lead to protein misfolding, which, in turn, can cause diseases ranging from Alzheimer's to diabetes," Karbstein said. "Nature might be using this to stall important biological processes and allow for quality control and regulation."

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Journal of Molecular Biology

Volume 405, Issue 1, 7 January 2011, Pages 3-17

An RNA Conformational Switch Regulates Pre-18S rRNA Cleavage

Allison C. Lamanna1, 1 and Katrin Karbstein1, 2, , 

1 Department of Chemistry, University of Michigan, 930 N. University, Ann Arbor, MI 48109-1055, USA

2 Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 48109-1055, USA

Received 19 August 2010; 

revised 27 September 2010; 

accepted 29 September 2010. 

Edited by D. E. Draper. 

Available online 8 October 2010. 

Abstract

To produce mature ribosomal RNAs (rRNAs), polycistronic rRNA transcripts are cleaved in an ordered series of events. We have uncovered the molecular basis for the ordering of two essential cleavage steps at the 3′-end of 18S rRNA. Using in vitro and in vivo structure probing, RNA binding and cleavage experiments, and yeast genetics, we demonstrate that a conserved RNA sequence in the spacer region between the 18S and 5.8S rRNAs base-pairs with the decoding site of 18S rRNA in early assembly intermediates. Nucleolar cleavage at site A2 excises this sequence element, leading to a conformational switch in pre-18S rRNA, by which the ribosomal decoding site is formed. This conformational switch positions the nuclease Nob1 for cytoplasmic cleavage at the 3′-end of 18S rRNA and is required for the final maturation step of 18S rRNA in vivo and in vitro. More generally, our data show that the intrinsic ability of RNA to form stable structural switches is exploited to order and regulate RNA-dependent biological processes.

Graphic Abstract

Research Highlights

► Cleavage at site A2 leads to a conformational switch in pre-18S rRNA. ► The decoding site is not formed in the early structure. ► Nob1 binds both structures but cleaves only the mature structure. ► Stabilizing the early structure delays Nob1-dependent cleavage in vivo. ► The switch orders cleavages at sites A2 and D.

Keywords: ribosome assembly; RNA conformational switch; RNA cleavage; RNP assembly

Abbreviations: rRNA, ribosomal RNA; H44, helix 44; ITS1, internal transcribed spacer 1

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Mesmo sendo boas mães elas não puderam salvar os mamutes peludos

Being Good Moms Couldn't Save the Woolly Mammoth

ScienceDaily (Dec. 21, 2010) — New research from The University of Western Ontario leads investigators to believe that woolly mammoths living north of the Arctic Circle during the Pleistocene Epoch (approx. 150,000 to 40,000 years ago) began weaning infants up to three years later than modern day African elephants due to prolonged hours of darkness.

By studying the chemical composition of adult and infant mammoth teeth, researchers were able to determine that woolly mammoths that once inhabited Old Crow, Yukon didn't begin eating plants and other solid foods before the age of two (and perhaps as late as three). (Credit: Image courtesy of University of Western Ontario)

This adapted nursing pattern could have contributed to the prehistoric elephant's eventual extinction. The findings were published recently in the journal, Palaeogeography, Palaeoclimatology, Palaeoecology.

By studying the chemical composition of adult and infant mammoth teeth, Jessica Metcalfe, an Earth Sciences PhD student working with professor Fred Longstaffe, was able to determine woolly mammoths that once inhabited Old Crow, Yukon didn't begin eating plants and other solid foods before the age of two (and perhaps as late as three) and considers predatory mammals like saber-toothed cats and a lack of sufficient vegetation to be the secondary reasons for delayed weaning.

"In modern Africa, lions can hunt baby elephants but not adults. They can't kill adults. But they can kill babies and by and large, they tend to be successful when they hunt at night because they have adapted night vision," explains Metcalfe, who examined fossil specimens alongside Grant Zazula of the Yukon Paleontology Program. "In Old Crow, where you have long, long hours of darkness, the infants are going to be more vulnerable, so the mothers nursed longer to keep them close."

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Palaeogeography, Palaeoclimatology, Palaeoecology

Volume 298, Issues 3-4, 15 December 2010, Pages 257-270

Nursing, weaning, and tooth development in woolly mammoths from Old Crow, Yukon, Canada: Implications for Pleistocene extinctions

Jessica Z. Metcalfea, , , Fred J. Longstaffea and Grant D. Zazulab

a Department of Earth Sciences, The University of Western Ontario, London, Ontario, Canada N6A 5B7

b Yukon Palaeontology Program, Department of Tourism & Culture, Government of Yukon, P.O. Box 2703, Whitehorse, Yukon, Canada Y1A 2C6

Received 13 May 2010; 

revised 27 September 2010; 

accepted 29 September 2010. 

Available online 7 October 2010. 

Abstract

This study investigates differences in the δ13Ccol, δ15N, δ13Csc, δ18Osc, Sr/Ca, and Ba/Ca values of juvenile and adult woolly mammoths (Mammuthus primigenius) from Old Crow, Yukon, Canada. The data indicate that nursing in woolly mammoths lasted at least three years, and was associated with minimal decreases in δ13Ccol (~ 0.2‰), large decreases in δ13Csc (~ 1.5‰), and large increases in δ15N (~ 2‰) and δ18Osc (~ 2‰) values. Sr/Ca and Ba/Ca ratios suggest that woolly mammoth juveniles began consuming plant foods between 2 and 3 “African Elephant Years” of age, much later than the initiation of weaning in modern elephants. We hypothesize that delayed weaning was an adaptation to increased predation risk and decreased food quality/quantity during the extended hours of darkness that occur in winter at high latitudes. Prolonged nursing and delayed weaning may have made mammoths particularly vulnerable to climatic stressors or human hunting.

Keywords: Stable isotopes; Trace elements; Carbon; Nitrogen; Oxygen; Strontium; Barium; Nursing; Weaning; Predation risk; Mammoth; Mammuthus primigenius; Extinction; Old Crow; Yukon

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Estranha nova mudança: simetria de Möbius em metamateriais

Strange New Twist: Researchers Discover Möbius Symmetry in Metamaterials

ScienceDaily (Dec. 21, 2010) — Möbius symmetry, the topological phenomenon that yields a half-twisted strip with two surfaces but only one side, has been a source of fascination since its discovery in 1858 by German mathematician August Möbius. As artist M.C. Escher so vividly demonstrated in his "parade of ants," it is possible to traverse the "inside" and "outside" surfaces of a Möbius strip without crossing over an edge. For years, scientists have been searching for an example of Möbius symmetry in natural materials without any success.

Berkeley Lab researcher have discovered Möbius symmetry in metamolecular trimers made from metals and dielectrics. (Credit: Image by Chih-Wei Chang)

Now a team of scientists has discovered Möbius symmetry in metamaterials -- materials engineered from artificial "atoms" and "molecules" with electromagnetic properties that arise from their structure rather than their chemical composition.

Xiang Zhang, a scientist with the U.S. Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) and a professor at the University of California (UC) Berkeley, led a study in which electromagnetic Möbius symmetry was successfully introduced into composite metamolecular systems made from metals and dielectrics. This discovery opens the door to finding and exploiting novel phenomena in metamaterials.

"We have experimentally observed a new topological symmetry in electromagnetic metamaterial systems that is equivalent to the structural symmetry of a Möbius strip, with the number of twists controlled by sign changes in the electromagnetic coupling between the meta-atoms," Zhang says. "We have further demonstrated that metamaterials with different coupling signs exhibit resonance frequencies that depend on the number but not the locations of the twists. This confirms the topological nature of the symmetry."

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Phys. Rev. Lett. 105, 235501 (2010) [4 pages]

Optical Möbius Symmetry in Metamaterials

Chih-Wei Chang1, Ming Liu1, Sunghyun Nam1, Shuang Zhang1, Yongmin Liu1, Guy Bartal1, and Xiang Zhang1,2,* 

1Nanoscale Science and Engineering Center, 3112 Etcheverry Hall, University of California, Berkeley, California 94720-1740, USA

2Materials Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA

See Also: Publisher's Note

Received 29 April 2010; revised 7 October 2010; published 2 December 2010; corrected 6 December 2010

We experimentally observed a new topological symmetry in optical composites, namely, metamaterials. While it is not found yet in nature materials, the electromagnetic Möbius symmetry discovered in metamaterials is equivalent to the structural symmetry of a Möbius strip, with the number of twists controlled by the sign change of the electromagnetic coupling between the meta-atoms. We further demonstrate that metamaterials with different coupling signs exhibit resonance frequencies that depend only on the number but not the locations of the “twists,” thus confirming its topological nature. The new topological symmetry found in metamaterials may enable unique functionalities in optical materials.

© 2010 The American Physical Society

URL:

http://link.aps.org/doi/10.1103/PhysRevLett.105.235501

DOI:

10.1103/PhysRevLett.105.235501

PACS:

81.05.Xj, 03.65.Vf, 73.20.Mf, 78.67.Pt

*Corresponding author: xiang@berkeley.edu

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Darwin nada sabia: a maquinaria da sinapse do cérebro é finamente ajustada

The research team, led by Seth Grant of the Sanger Institute near Cambridge, England, compiled the first exact inventory of all the protein components of the synaptic information-processing machinery.  No fewer than 1,461 proteins are involved in this biological machinery, they report in the current issue of Nature Neuroscience....

Each neuron in the human brain makes an average 1,000 or so connections with other neurons.  There are 100 billion neurons, so the brain probably contains 100 trillion synapses, its most critical working part.

Source/Fonte

At the side of a synapse that belongs to the transmitting neuron, an electrical signal arrives and releases packets of chemicals.  The chemicals diffuse quickly across the minute gap between the neurons and dock with receptors on the surface of the receiving neuron.

These receptors feed the signals they receive to a delicate complex of protein-based machines that process and store the information.

The 1,461 genes that specify these synaptic proteins constitute more than 7 percent of the human genome’s 20,000 protein-coding genes, an indication of the synapse’s complexity and importance.

Dr. Grant believes that the proteins are probably linked together to form several biological machines that process the information and change the physical properties of the neuron as a way of laying down a memory.

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Read more here/Leia mais aqui: The New York Times

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NOTA DESTE BLOGGER:

Darwin era profundamente ignorante sobre uma simples bactéria, muito mais profundamente ignorante em relação ao cérebro humano. Se ele sentia arrepios só de imaginar que o olho fosse produto do mero acaso e da fortuita necessidade através da seleção natural, ele deveria ter espasmos epilépticos só de imaginar isso para o cérebro.

Dizem, retórica vazia, que Darwin eliminou de uma vez por todas a linguagem teleológica da biologia evolutiva? Será mesmo? Se a sua profunda ignorância nos deu somente um melhor entendimento da microevolução, Darwin é encontrado nú epistemicamente quanto à macroevolução. A extrema complexidade que é a maquinaria das sinapses do cérebro, e a linguagem teleológica usada para descrever suas funções (telos) deveria fazer com que os cientistas se perguntassem: mero acaso? fortuita necessidade? através da seleção natural ao longo de milhões, bilhões de anos???

Fui, nem sei por que, pensando que a cada dia que passo com a leitura da literatura especializada eu fico cada vez mais cético de Darwin e de sua teoria da evolução através da seleção natural. E esta foi a maior ideia que toda a humanidade já teve? e não consegue explicar nem um simples flagelo bacteriano? Quanto mais o cérebro humano.

Icons of Evolution: Jonathan Wells e o Archaeopteryx

Abaixo-assinado contra o famigerado KIT GAY

Abaixo-assinado Somos contra o maior escândalo deste País, o KIT GAY

Para:Presidente da República Federativa do Brasil; Congresso Nacional do Brasil; Supremo Tribunal Federal; Assembléias Legislativas

Somos contra o maior escândalo deste País, o KIT GAY 

Não aceitamos que nossas crianças de 7,8,9 e 10 anos recebam esse tal de KIT GAY. 

Neste Kit Gay há 2 vídeos com o Titulo Contra homofobia, mas na verdade nesses vídeos contém mensagens subliminares para as nossas crianças, induzindo-as a homossexualidade. 

Uma coisa é preconceito...Outra coisa é fazer apologia ao homossexualismo!!! 

Neste Kit Gay, na verdade, é um estímulo ao homossexualismo e incentivo a promiscuidade e a confusão de discernimento da criança sobre o conceito de família. 

Na primeira das histórias homossexuais do Kit Gay, segundo o Jornal da Câmara dos Deputados, mostra-se um garoto chamado Ricardo, de 14 anos que, certa hora, vai ao banheiro urinar e encontra um colega seu. Enquanto ele urina, Ricardo dá uma olhada para o lado e vê o pênis de seu amigo e se apaixona pelo garoto. Ao retornar para a sala de aula, a professora da classe chama o menino pelo seu nome (Ricardo), onde o mesmo cerra seus lábios, pois não quer ser chamado de Ricardo, e diz que quer ser chamado de "Bianca". 

Na outra história do Kit Gay, o comportamento de duas meninas lésbicas de aproximadamente 13 anos de idade é posto como exemplar para as outras, e a comissão ainda discutiu a profundidade que a língua de uma menina deve entrar na boca da outra ao realizar o beijo lésbico para os vídeos(Kit Gay), que já estão em fase de licitação para começarem a serem distribuídos em todos a escolas estaduais e municipais do PAÍS. 

Uma coisa é preconceito, outra coisa é APOLOGIA AO HOMOSSEXUALISMO!!! 

Façam valer imediatamente nossos valores contra essa imposição que querem colocar para as nossas crianças. 

Essa comissão de Direitos Humanos e Minorias que nós colocar o escárnio da sociedade. Eles querem aliciar nossas crianças com esse KIT GAY.

Os signatários

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Assine aqui: Petição Pública

Humor Darwinista: um blog científico prá lá de sério

Gente, não deixem de visitar frequentemente este blog que, apesar do título Humor Darwinista, é um dos blogs científicos mais sério que conheço. Cita a literatura científica com exatidão e remete seus leitores às citações de Darwin e muitos eminentes cientistas evolucionistas para que todos possam conferir o que foi dito.

No começo desse blog, eu discordei com o Iba Mendes, autor responsável, sobre o nome 'tedeísmo' para se referir ao corpus teórico do Design Inteligente. Picuinhas linguísticas à parte, não deixei de visitar o blog picante, mas incisivo, e como sempre faço com os blogs que me agradam, já relacionei na minha lista de favoritos. Note que não relaciono apenas o lado contra Darwin, mas uma boa parcela de sites estritamente darwinianos. 

Aqui, diferentemente da Folha de São Paulo e do resto da Grande Mídia Tupiniquim, nós não seguimos ao Marcelo Leite, jornalista especial da Folha de São Paulo, que afirmou no encerramento de conferência sobre evolução na USP: "Não damos espaço". E eles é quem são cientificamente objetivos y otras cositas mais. 

Ora vão caçar sapos de botas epistêmicas na lagoa de Down...

Iba, apesar de não conhecê-lo pessoalmente, seja bem-vindo!!!

Os limites da adaptação complexa: uma análise baseada em um modelo simples de populações bacterianas estruturadas

The Limits of Complex Adaptation: An Analysis Based on a Simple Model of Structured Bacterial Populations

 

Douglas Axe 

Abstract 

To explain life's current level of complexity, we must first explain genetic innovation. Recognition of this fact has generated interest in the evolutionary feasibility of complex adaptations--adaptations requiring multiple mutations, with all intermediates being non-adaptive. Intuitively, one expects the waiting time for arrival and fixation of these adaptations to have exponential dependence on d, the number of specific base changes they require. Counter to this expectation, Lynch and Abegg have recently concluded that in the case of selectively neutral intermediates, the waiting time becomes independent of d as d becomes large. Here, I confirm the intuitive expectation by showing where the analysis of Lynch and Abegg erred and by developing new treatments of the two cases of complex adaptation--the case where intermediates are selectively maladaptive and the case where they are selectively neutral. In particular, I use an explicit model of a structured bacterial population, similar to the island model of Maruyama and Kimura, to examine the limits on complex adaptations during the evolution of paralogous genes--genes related by duplication of an ancestral gene. Although substantial functional innovation is thought to be possible within paralogous families, the tight limits on the value of d found here (d ≤ 2 for the maladaptive case, and d ≤ 6 for the neutral case) mean that the mutational jumps in this process cannot have been very large. Whether the functional divergence commonly attributed to paralogs is feasible within such tight limits is far from certain, judging by various experimental attempts to interconvert the functions of supposed paralogs. This study provides a mathematical framework for interpreting experiments of that kind, more of which will needed before the limits to functional divergence become clear. 

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Princípios de design da sinalização do receptor nuclear: como que a rede complexa melhora a transdução de sinal

Molecular Systems Biology 6 Article number: 446 doi:10.1038/msb.2010.102

Published online: 21 December 2010

Citation: Molecular Systems Biology 6:446

Design principles of nuclear receptor signaling: how complex networking improves signal transduction

Alexey N Kolodkin1, Frank J Bruggeman1,2,3, Nick Plant4, Martijn J Moné1, Barbara M Bakker1,5, Moray J Campbell6, Johannes P T M van Leeuwen7, Carsten Carlberg8, Jacky L Snoep1,9,10 & Hans V Westerhoff1,10

Molecular Cell Physiology, VU University Amsterdam, Amsterdam, The Netherlands

Regulatory Networks Group, Netherlands Institute of Systems Biology, Amsterdam, The Netherlands

Life Sciences, Centre for Mathematics and Computer Science (CWI), Amsterdam, The Netherlands

Centre for Toxicology, Faculty of Health and Medical Sciences, University of Surrey, Guildford, UK

Department of Pediatrics, University Medical Center Groningen, Groningen, The Netherlands

Department of Pharmacology and Therapeutics, Roswell Park Cancer Institute, Elm & Carlton Streets, Buffalo, NY, USA

Department of Internal Medicine, Erasmus MC, Rotterdam, The Netherlands

Life Sciences Research Unit, University of Luxembourg, Luxembourg, Luxembourg

Department of Biochemistry, Stellenbosch University, Matieland, South Africa

Manchester Centre for Integrative Systems Biology, Manchester Interdisciplinary Biocentre, The University of Manchester, Manchester, UK

Correspondence to: Hans V Westerhoff1,10 Manchester Centre for Integrative Systems Biology, Manchester Interdisciplinary Biocentre, The University of Manchester, 131 Princess Street, Manchester M1 7DN, UK. Tel.: +44 161 306 4407; Fax: +44 161 306 4556; Email: hans.westerhoff@manchester.ac.uk

Received 23 March 2010; Accepted 21 October 2010; Published online 21 December 2010

Article highlights

Nuclear receptors often function in the cytoplasm.

A triple conveyor belt pumps ligand (signal) into the nucleus and onto the DNA.

The active export of importins enhances signaling to the nucleus.

Sharing a single nuclear pore may reduce rather than increase crosstalk.

Synopsis

Nuclear receptors (NRs) derive their family name from the early observation that they are located in the nucleus, despite responding to extracellular signals such as hormones (e.g., cortisol) (Fanestil and Edelman, 1966). According to the ‘classical’ paradigm of NR signaling, the NR resides in the nucleus, attached to a DNA response element, waiting for its ligand to bind. The actual systems have multiple additional features (reviewed in Cutress et al, 2008; Cao et al, 2009;Levin, 2009a; Bunce and Campbell, 2010), such as that NRs shuttle between the nucleus and the cytoplasm (Von Knethen et al, 2010) and ligand addition changes receptor location dynamically (Pratt et al, 1989; Liu and DeFranco, 2000; Kumaret al, 2004, 2006; Tanaka et al, 2005; Heitzer et al, 2007; Prüfer and Boudreaux, 2007; Ricketson et al, 2007; Cutress et al, 2008): Figure 1 summarizes the current understanding of the topology of the reaction networks involved in NR signaling, in systems biological graphical notation (SBGN), with NR activation, importin-α and -β binding, nuclear pore complex (NPC)-mediated import, recycling of importins, NR binding to target promoter sequences, exportin-mediated nuclear export of the NR, exportin cycling and free energy-driven Ran recycling. This topology is surprisingly complex when compared with the ‘classical’ paradigm. To address to what extent this extra complexity is just detail or contributes essential functionality, we have simulated the dynamics of the NR transcriptional response in maximally realistic mathematical models of increasingly complex designs.

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NOTA DESTE BLOGGER:

Embora os autores sejam evolucionistas (até onde sei), repare na linguagem teleológica empregada no Abstract! E ainda dizem que Darwin, de uma vez por todas, eliminou a linguagem teleológica da ciência. É muita bazófia para o homem que teve a maior ideia que toda a humanidade já teve, mas que nunca é corroborada no contexto de justificação teórica.

Fui, nem sei por que, pensando: a teleologia realmente é uma amante que os evolucionistas não gostam de aparecer tratando de amores publicamente, mas que eles não ignoram sua presença, ah, isso não. Design empiricamente detectado!!!

Basta ler a literatura especializada: quase que 100% teleológica!!! Darwin, sinto muito, mas você e os seus atuais discípulos não estão pra lá de Marrakesh em termos teleológicos. Queria ver a cara do Darwin...