74 research outputs found
Erwin Schroedinger, Francis Crick and epigenetic stability
Schroedinger's book 'What is Life?' is widely credited for having played a
crucial role in development of molecular and cellular biology. My essay
revisits the issues raised by this book from the modern perspective of
epigenetics and systems biology. I contrast two classes of potential mechanisms
of epigenetic stability: 'epigenetic templating' and 'systems biology'
approaches, and consider them from the point of view expressed by Schroedinger.
I also discuss how quantum entanglement, a nonclassical feature of quantum
mechanics, can help to address the 'problem of small numbers' that lead
Schroedinger to promote the idea of molecular code-script for explanation of
stability of biological order.Comment: New and improved version of the essay, now published in the online
journal 'Biology Direct'. Contains more expanded discussion on entanglement.
18 pages, 2 figures. The file includes open reviews by E.Koonin, V.Vedral and
E.Karsent
Epigenetics: What it is about?
Epigenetics has captured the attention of scientists in the past decades, yet
its scope has been continuously changing. In this paper, we give an overview on
how and why its definition has evolved and suggest several clarification on the
concepts used in this field, in particular, on the notions of epigenetic
information, epigenetic stability and epigenetic templating. Another issue that
we address is the role of epigenetic information. Not only it is important in
allowing alternative interpretations of genetic information, but it appears to
be important in protecting the genetic information, moreover, we suggest that
this function appeared first in evolution and only later on the epigenetic
mechanisms were recruited to play a role in cell differentiation.Comment: 7 pages, 3 figure
Oligoribonuclease is a common downstream target of lithium-induced pAp accumulation in Escherichia coli and human cells
We identified Oligoribonuclease (Orn), an essential Escherichia coli protein and the only exonuclease degrading small ribonucleotides (5mer to 2mer) and its human homologue, small fragment nuclease (Sfn), in a screen for proteins that are potentially regulated by 3′-phosphoadenosine 5′-phosphate (pAp). We show that both enzymes are sensitive to micromolar amounts of pAp in vitro. We also demonstrate that Orn can degrade short DNA oligos in addition to its activity on RNA oligos, similar to what was documented for Sfn. pAp was shown to accumulate as a result of inhibition of the pAp-degrading enzyme by lithium, widely used to treat bipolar disorder, thus its regulatory targets are of significant medical interest. CysQ, the E.coli pAp-phosphatase is strongly inhibited by lithium and calcium in vitro and is a main target of lithium toxicity in vivo. Our findings point to remarkable conservation of the connection between sulfur- and RNA metabolism between E.coli and humans
- …