How sticky toepads evolved in geckos


Download 501 b.
bet8/55
Sana21.08.2018
Hajmi501 b.
1   ...   4   5   6   7   8   9   10   11   ...   55

Popularly dubbed “the book of life,” the human genome is extraordinarily difficult to read. But without full knowledge of its grammar and syntax, the genome’s 2.9 billion base-pairs of adenine and thymine, cytosine and guanine provide limited insights into humanity’s underlying genetics.…

  • As expected, the researchers identified different sequences that promote or start gene activity, enhance its activity and define where it occurs in the body during development. More surprising, said Ren, was that the structural organization of the cis-regulatory elements are grouped into discrete clusters corresponding to spatial domains. “It’s a case of form following function,” he said. “It makes sense.”



  • Good interference creates epigenetic memory:  Why would some RNA transcripts interfere with others?  It’s all part of a regulatory dance, scientists are finding out.  Now, a new role for RNA interference (RNAi) was announced on PhysOrg: recognizing and silencing foreign DNA, such as strands introduced by viruses.  It’s heritable, too:  “Once identified, an ‘epigenetic memory’ of the foreign DNA fragments is created and can be passed on from one generation to the next, permanently silencing the gene.”  This has an eerie echo of Lamarckian “inheritance of acquired characteristics.”

    • Good interference creates epigenetic memory:  Why would some RNA transcripts interfere with others?  It’s all part of a regulatory dance, scientists are finding out.  Now, a new role for RNA interference (RNAi) was announced on PhysOrg: recognizing and silencing foreign DNA, such as strands introduced by viruses.  It’s heritable, too:  “Once identified, an ‘epigenetic memory’ of the foreign DNA fragments is created and can be passed on from one generation to the next, permanently silencing the gene.”  This has an eerie echo of Lamarckian “inheritance of acquired characteristics.”



    Once the DNA is identified as foreign and silencedan epigenetic memory is created that silences the foreign gene from one generation to the next. While the inheritance of this memory requires further exploration, the authors showed that successive generations of C. elegans are unable to express the foreign DNA even if the corresponding piRNA is absent.

    • Once the DNA is identified as foreign and silenced, an epigenetic memory is created that silences the foreign gene from one generation to the next. While the inheritance of this memory requires further exploration, the authors showed that successive generations of C. elegans are unable to express the foreign DNA even if the corresponding piRNA is absent.



    A vaster landscape:  Geneticists used to speak of the “genetic landscape” but now there’s a vaster field: the “epigenetic landscape.”  James Ferrell discussed this concept in his review, “Bistability, Bifurcations, and Waddington’s Epigenetic Landscape” in Current Biology (Volume 22, Issue 11, R458-R466, 5 June 2012), saying, “Waddington’s epigenetic landscape is probably the most famous and most powerful metaphor in developmental biology.”  His rather lengthy review did not contain any of the following words: Darwin, phylogeny, evolution.

    • A vaster landscape:  Geneticists used to speak of the “genetic landscape” but now there’s a vaster field: the “epigenetic landscape.”  James Ferrell discussed this concept in his review, “Bistability, Bifurcations, and Waddington’s Epigenetic Landscape” in Current Biology (Volume 22, Issue 11, R458-R466, 5 June 2012), saying, “Waddington’s epigenetic landscape is probably the most famous and most powerful metaphor in developmental biology.”  His rather lengthy review did not contain any of the following words: Darwin, phylogeny, evolution.



    In the book The Mysterious Epigenome: What Lies Beyond DNA mentioned above, Woodward and Gills describe in verbal animation what it would be like to ride a sci-fi ship into the nucleus of a cell and watch gene regulation at work.  Their second-to-last chapter, “An Infinitely More Complex Genome,” is like a 4th of July Grand Finale – a rapid-fire series of new discoveries and possibilities that portend a golden age of research in the years ahead, described in vivid metaphors like air traffic control, overlapping messages, codes here there and everywhere, and functional treasure in the “junk“ yard.

    • In the book The Mysterious Epigenome: What Lies Beyond DNA mentioned above, Woodward and Gills describe in verbal animation what it would be like to ride a sci-fi ship into the nucleus of a cell and watch gene regulation at work.  Their second-to-last chapter, “An Infinitely More Complex Genome,” is like a 4th of July Grand Finale – a rapid-fire series of new discoveries and possibilities that portend a golden age of research in the years ahead, described in vivid metaphors like air traffic control, overlapping messages, codes here there and everywhere, and functional treasure in the “junk“ yard.



    Two practical effects of the Epigenetic Revolution will be: (1) a realization that we are not slaves of our DNA, but that with healthy lifestyle changes, we can control the expression of genes (for instance, a vigorous workout at the gym makes observable effects on gene regulatory tags); (2) increasing pressure against Darwinism.  The realization is growing that there is far more functional information in the cell than neo-Darwinists ever imagined.  If the genetic code was a challenge to explain by undirected processes operating stepwise by natural selection, what will be the reaction to codes upon codes, master regulators of other regulators, and millions of molecules performing a living symphony?

    1   ...   4   5   6   7   8   9   10   11   ...   55




    Ma'lumotlar bazasi mualliflik huquqi bilan himoyalangan ©fayllar.org 2020
    ma'muriyatiga murojaat qiling