Ciências Biológicas - Seguimento 2007

Tópico em 'Biosfera e Atmosfera' iniciado por Zoelae 18 Jan 2007 às 14:46.

  1. Rog

    Rog
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    Esperemos é que não se vire o feitiço contra o feiticeiro, não vá estas bactérias nos "limpar" a nós...:lol:
    Qual a probabilidade que achas de estas parentes da bactéria que referes, poderem vir a criar mutações que possam evoluir para algo menos benéfico?
    É um risco real ou simplesmente não existe?
     
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  2. Minho

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    Re: Biotecnologia

    Excelente para limpar o CCD :D :thumbsup:
    Acabaram-se as manchas escuras e os retoques no Photoshop
     
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  3. Zoelae

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    Re: Biotecnologia - Seguimento 2007

    Bom eu não sou formado em Biotecnologia e não sei exatamente o que lhe fazem à bacterias. Bom elas apesar de sofrerem grande numero de mutações, não será desta forma que poderão tornar-se virulentas. As bacterias podem obter material genético exógeno, ou seja obter os genes virulentos, de 4 formas:
    conjugação (troca de material genético com outras bactérias),
    Transmissão (otenção de material genético livre no meio proveniente de outras bactérias mortas)
    transdução ( materias genético obtido através vírus que infectam as bactérias(bacteriófagos))
    transposição (genes saltitantes, esta é uma forma indirecta)

    Ora se adquire genes virulentos pode-nos infectar, bom penso que lhe são delectados mtos genes, p ex aqueles necessários para sobreviverem no intestino, relacionados com a adesão, metabolismo etc, é portanto mto pouco provável, além disso ela tem de ser ingerida para causar doença.
     
  4. Rog

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    Pacientes radioactivos disparam alarmes nos EUA


    Jane Sutton, Reuters
     
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  5. Rog

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    Cientistas descobrem que plantas podem ser regadas com água salgada
    da Efe, em Madri


    As plantas são capazes de detectar o grau de salinidade do solo e se defender dela, de acordo com uma pesquisa que será publicada no sábado (12) pela revista "Molecular Cell". Elas são capazes de desenvolver mecanismos de defesa contra as agressões externas como o excesso de sal, a ausência de água ou a falta de nutrientes no solo. A descoberta ajudará na criação de um gramado transgênico que poderia ser regado com água salgada.

    [​IMG]

    Divulgação

    Resultados indicam possibilidade de regar plantas com água salgada
    O responsável pelo estudo é Armand Albert, pesquisador do Instituto de Química Física Rocasolano do Centro Superior de Pesquisas Científicas, na Espanha. As experiências foram realizadas com a Arabidopsis thaliana, da mesma família que a mostarda.

    As plantas detectam e se defendem dos estímulos externos mediante um mecanismo molecular. Nele atuam as proteínas quinase e fosfatase, que se organizam para receber os estímulos ambientais e transformá-los em um sinal químico que desencadeia a resposta observada.

    O excesso de sódio no solo é tóxico para as plantas e desajusta o equilíbrio entre os diferentes sais necessários para um crescimento normal. Em situações de estresse salino, as plantas devem manter as concentrações intracelulares de sódio baixas.

    Para alcançar esse equilíbrio, a quinase e a fosfatase colocam em andamento um transportador na membrana celular que bombeia o excesso de sódio para fora da célula, restabelecendo assim o equilíbrio salino da planta.

    A importância da descoberta se deve, basicamente, à identificação da estrutura atômica das proteínas e dos determinantes moleculares que afetam o processo.

    Com a descoberta, será mais fácil realizar uma busca sistemática de espécies naturais que apresentem alterações nessas proteínas ou preparar vegetais transgênicos que sejam hiper-resistentes ao sal.

    Folha ON-LINE
     
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  6. Zoelae

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    Ciências Biológicas - Seguimento Dezembro 2007

    Afinal as Plantas vivas também emitem metano...

    Uma descoberta insólita, em 2006, alarmou os cientistas.
    Afinal, algumas plantas, nomeadamente as plantas lenhosas produzem metano, um gás com efeito de estufa. O mecanismo ainda permanece desconhecido e intensa investigação está a ser feita, pensa-se que o metano poderá derivar de um polissacarídeo ramificado presente na parede celular das plantas, a pectina.​
    Até aqui pensava-se que a única fonte de metano provinha da decomposição, por processos anaeróbicos, de matéria orgânica, realizada por bactérias.
    Nesta descoberta realizada por Frank Keppler e a sua equipa compararam-se as emissões de plantas normais sem qualquer tratamento, com as emissões de plantas submetidas a estirilização prévia por raios Gama (para matar qualquer bactéria existente), verificando-se que apresentavam emissão de metano semelhante.

    NewScientist


    "The lungs of the planet are belching methane
    12 January 2006
    NewScientist.com news service
    Zeeya Merali

    IT'S not just farting cows and belching sheep that spew out methane. Living plants have been disgorging millions of tonnes of the potent greenhouse gas into the atmosphere every year - without anybody noticing.

    The concentration of methane in the atmosphere has almost tripled since pre-industrial times. Environmental scientists thought they had identified all natural sources where bacteria convert organic plant matter to methane, such as swamps, wetlands and rice paddies. These bacteria only thrive in wet, oxygen-poor environments; they cannot survive in air.

    So Frank Keppler, an environmental engineer at the Max Planck Institute for Nuclear Physics in Heidelberg, Germany, was surprised when he saw signs of methane being emitted by plants he was examining in normal air. "If we were following the textbook, we would have ignored it as a mistake," he says.


    How will this affect the fight against global warming?
    Discuss this story >> But Keppler and his colleagues decided to investigate further. They measured the amount of methane given off by plant debris - bits of grass and leaves from local and tropical plants - in methane-free chambers. To rule out the possibility that bacteria were at work, they bombarded the plants with gamma radiation to sterilise them.

    The team saw similar levels of methane produced by both sterilised and un-sterilised leaves. "We realised that we were looking at a previously unrecognised process," Keppler says. They still don't know exactly what is happening, but believe that pectin, a substance contained in plant cell walls, plays a part in the methane-making mechanism (Nature, vol 439, p 187).

    When the group repeated the tests with living plants they were stunned by the amount of methane created. They estimate that, globally, living plants produce between 63 and 236 million tonnes of methane per year, with plant debris adding another 1 to 7 million tonnes. This would make plants responsible for roughly 10 to 30 per cent of global methane production.

    "This effect is completely missing from climate change and biogeochemical models," says Peter Cox of the Centre for Ecology and Hydrology at Winfrith in Dorset, UK. He suggests that a new source of methane could help solve some climate mysteries. One such puzzle was posed last year when satellite observations revealed that tropical rainforests are emitting more methane than expected (New Scientist, 26 March 2005, p 20). Thomas Wagner from the University of Heidelberg in Germany, who led last year's study, thinks Keppler may have found the culprit. "This new source is in good agreement with our results," he says.

    The finding should also encourage new strategies for cutting man-made methane emissions, says Chris Jardine of the University of Oxford's UK methane project."



    Nature


    Será que esta descoberta afecta a visão que temos das alterações climáticas, aquecimento global e efeito de estufa?
     
  7. Luis França

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    Jurassic Fungus? Scientists Discover Ancient Carnivorous Fungus Encased in Amber

    [​IMG]

    While the idea of a reanimated flesh eating fungus causing havoc on a private island in the Pacific might sound terrifying, or at least more interesting than Jurassic Park 3, humans have no real cause to fear. Besides the fact that nobody is actually trying to reanimate the fungus, the carnivorous fungus preyed mainly on tiny animals.

    The fungus, which the German researchers who discovered it are suggesting may be the oldest carnivorous fungus ever found, was discovered in amber along with some of its prey. The scientists believe that the nematodes found in the amber were a food source for the fungus.

    Researchers think the fungus snared the tiny creatures with some sort of sticky hoop before consuming the animals. The fungus has several projecting parts known as hyphae. These were covered with tiny rings with an adhesive substance, which would trap the creature’s prey before it was consumed.
     
  8. Luis França

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    Cosmic cockroaches faster developers, Russian scientists say

    [​IMG]

    VORONEZH, January 17 (RIA Novosti) - Cockroaches conceived in space onboard the Russian Foton-M bio satellite have developed faster and become hardier than 'terrestrial' ones, a research supervisor said on Thursday.
    The research team has been monitoring the cockroaches since they were born in October. The scientists established that their limbs and bodies grew faster.
    "What is more, we have found out that the creatures... run faster than ordinary cockroaches, and are much more energetic and resilient," Dmitry Atyakshin said.

    Cockroaches, as well as other types of insects, can give birth several times after one impregnation, and the cockroaches that conceived during the bio-satellite's September 14-26 flight have since given birth to their second and third batches of offspring.
    "The second and third batches did not show these peculiarities of growth and physiology," the scientist noted.
    'Ordinary' cockroaches are already known for their extraordinary resilience. Some species can last almost an hour without oxygen or a month without food, and are able to withstand high doses of radiation.

    The September 14-26 flight was part of an ongoing experiment into the effects of space flight by the Institute of Biomedical Problems (IBMP). The creatures were sealed in special containers, and a video camera filmed them during the flight.
     
  9. Zoelae

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    Re: Ciências Biológicas - Seguimento Dezembro 2007



    Foi recentemente publicado um estudo que contradiz este que eu tinha colocado aqui há 1 ano e tal, podemos estar mais descansados que afinal as Plantas não produzem metano, mas não há certeza absoluta.

    Methane Emissions? Don't Blame Plants
    By Claire Thomas
    ScienceNOW Daily News
    14 January 2009

    Plants do not make the powerful greenhouse gas methane, according to new research that contradicts a controversial finding made in 2006. Instead, plants appear to merely be passing gas, so to speak, originally made by soil microbes.
    Methane comes from a variety of sources, including gas leaks, forest fires, and, of course, cow burps. Microbes in wetland soil can produce methane anaerobically (without using oxygen), but the idea that it can be produced aerobically (using oxygen) by plants, and on a large scale, is still extremely controversial. In 2006, geochemist Frank Keppler of the Max Planck Institute of Nuclear Physics in Heidelberg, Germany, conducted experiments on dead leaves and in greenhouses and concluded that many kinds of plants--through some mysterious mechanism--contribute to methane production. All told, plants could be to blame for 10% to 45% of the world's methane emissions, Keppler reported (Science, 13 January 2006, p. 159).

    "This finding was shocking," recalls Euan Nisbet of Royal Holloway, University of London, in Egham, U.K. If true, both plant biochemistry and global methane budget would need a major reexamination. It could also mean that the human contribution to global warming is less than previously thought.

    Nisbet's team set about to investigate Keppler's findings by growing the same plants, including celery (Apium graveolens) and a type of rice (Oryza sativa), in the absence of external sources of the greenhouse gas. The group found no trace of methane, suggesting that the plants alone cannot make the gas. In a separate experiment, the team placed the plants in water containing dissolved methane. Sure enough, the roots drew up the methane-soaked water and the leaves then pushed out the gas and water vapor--a process known as transpiration.

    The researchers also tried to find a chemical pathway by which the plants could make methane aerobically. They came up empty: None of the plants' genes codes for enzymes similar to those made in methane-producing microbes. "This showed that the plants were not guilty," says co-author Christopher Howe of the University of Cambridge in the U.K. The findings are published online today in the Proceedings of the Royal Society B.

    Keppler, now at the Max Planck Institute for Chemistry in Mainz, agrees with some of the team's conclusions, saying that transpiration does play a role in plant emissions of methane. But he still holds firm that methane can be produced in plants via a new, unidentified biochemical pathway. Nisbet is skeptical: "We're not saying it is not there, but we certainly couldn't find it."

    Science
     
  10. Orion

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    Foi desenvolvida uma estirpe da gripe aviária que é capaz de passar despercebida ao sistema imunitário humano (vá-se lá saber porquê):

    http://rt.com/news/169880-swine-flu-virus-modified/

    Mais uma arma biológica :hmm:
     
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  11. camrov8

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    Nada de estranho é a ciência, como arma biológica há melhores doenças tenho mais medo do ebola do antrax e da extinta Varíola, que só existe em dois laboratórios
     

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