epigenetic modifications

Did Dobzhansky see the UV light of creation?

Analemma. The sun’s position in the sky, photographed from the same location at the same time of day throughout a year, forms an analemma. This shows the sun’s apparent swinging from its northernmost position, at the analemma’s uppermost point, at summer solstice, to its southernmost position/lowest point, at winter solstice. My comment: Does this remind anyone else of a one-sided nonorientable surface obtained by cutting a closed band into a single strip with linked ends that can be used to…

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Understanding cell type differentiation

Understanding the Stem Cell Niche Description: Stem cells provide an attractive model to study human physiology and disease. However, technical challenges persist in the biological characterization and manipulation of stem cells in their native microenvironment. The Scientist brings together a panel of experts to discuss interactions between stem cells and external cues, and the role of the stem cell niche in development and disease. Topics to be covered include the molecular mechanisms of hematopoietic stem cell niche interactions and techniques…

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Vitamin B3 and DNA repair

Role of Nicotinamide in DNA Damage, Mutagenesis, and DNA Repair Conclusion: Nicotinamide, which is the dietary precursor for NAD+, provides a substrate for PARP-1 activity…. In various murine models, PARP-1 inhibition was shown to favor apoptotic cell death, reduce inflammatory response, and reduce genomic sensitivity to various carcinogens. However, extrapolation of these data to human, particularly when physiological regimes involved in human carcinogenesis, should be done cautiously. Further studies are needed to determine the effect of high-dose nicotinamide on in…

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Tet3 regulation of nutrient-dependent cell type differentiation

Tet3 regulates synaptic transmission and homeostatic plasticity via DNA oxidation and repair was reported as: Neurons constantly rewrite their DNA Excerpt: “The scientists say they have discovered another mechanism used by neurons to maintain relatively consistent levels of synaptic activity so that neurons can remain responsive to the signaling around them. If synaptic activity increases, Tet3 activity and base excision of tagged cytosines increases. This causes the levels of GluR1 at synapses to decrease, in turn, which decreases their overall…

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Questions about life’s diversity

Questions about life can be answered in the context of what sustains it. 1) Answers must explain the diversity of life. 2) The diversity of life may help to explain the purpose of life. 3) Explaining the purpose of life may assist anyone who does not think they will live forever. 4) Answers to questions about life that explain life’s diversity must include what is known about the conserved molecular mechanisms that link differences in morphological and behavioral phenotypes in…

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Nutrient-dependent gene duplication in plants (but not animals?)

Divergence of Gene Body DNA Methylation and Evolution of Plant Duplicate Genes Excerpt 1) “A recent study demonstrated that the DNA methylation in promoter may play a significant role for functional divergence of duplicated genes in human [48].” Excerpt 1 from the cited work [48]: “For 73% of gene pairs, one copy is always hypomethylated compared with the other. This refutes the idea that [RNA-directed] DNA methylation of genes is strictly determined in a tissue-by-tissue manner and indicates the presence…

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