James Le Fanu: Why Us? (The limitations of science)

by David Turell , Sunday, June 21, 2009, 22:48 (5417 days ago) @ David Turell

Talk with your friend again. There are now six different types of interference and micro DNA's that help to manage gene expression. It appears that a great portion of 'junk' DNA will be useful RNA. I'm just finishing an article on Epigenetic Research in the Quarterly Review of Biololgy, June issue, that is more a compendium of the research than reaching conclusions at this point. There are four or five schemes of epigenetic systems, znd Lemarkism is making a comeback of sorts. There is viral junk, but how much true junk is unknown at this time. - A summary of some of the material covered by the review article: The several types of epigenetic systems include: 1) inheritance though self-sustaining feedback loops, "metabolic circuits through which different patterns of activity can be maintained, resulting in alternative heritable cell phenotypes". The studies go back to 1957 in E. coli. 2) Structural inheritance by changes in 3-D protein folding passing from mother cell to daughter cell, studied in Paramecium in 1965. 3) Chromatin marking, methyl groups attached to DNA, "bound histone and non-histone proteins and associated RNA molecules". "DNA methylation is involved in many important functions: defense against genomic parasites, regulation and maintenance of gene activity patterns, stabilization of chromosomal structure, and DNA replication and repair." This is seen in both unicellar and multicellular organisms. 4) RNA mediated processes: a) gene silencing; b) guiding, targeting and assisting in transmitting variation in chromatin structure which is reproduced in daughter cells; c) "targeting DNA base sequences and guiding changes in them that are then replicated by DNA polymerases." - This 38-page article indicates how complex this area currently is, and that many years of research are ahead to sort all of this out and reach a greater degree of understanding.