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16th May of 2013

Details: Category: Research

Figura1 Investigation from the Spanish national Research Council (CSIC) has revealed new binding mechanisms of carbohydrates with quadruplex DNA. These results raise the possibility of developing carbohydrates as anticancer drugs.
DNA quadruplex structures are usually located at the telomeres (the end of chromosomes), thought they have been recently observed in oncogene promoters. In contrast with the well-known double helix, in these regions DNA adopts structures of quadruplex helix consisting of a square arrangement of guanines called tetrads.

Reference: Irene Gómez-Pinto, Empar Vengut-Climent, Ricardo Lucas, Anna Aviñó, Ramón Eritja, Carlos González, Juan Carlos Morales. Carbohydrate–DNA Interactions at G-Quadruplexes: Folding and Stability Changes by Attaching Sugars at the 5’-End. Chem. Eur. DOI: 10.1002/chem.201203902
http://onlinelibrary.wiley.com/doi/10.1002/chem.201203902/full

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FRET The use of commercial long-wavelength (>650 nm) laser dyes in many biophotonic applications has several important limitations, including low absorption at the standard pump wavelength (532 nm) and poor photostability. A research group headed by L. Cerdán from IQFR, in collaboration with researchers from Universidad Complutense de Madrid and Universidad del Pais Vasco, have demostrated that the use of Förster type (FRET) energy transfer can overcome these problems to enable efficient, stable near-IR lasing in a colloidal suspension of latex nanoparticles containing a mixture of Rhodamine 6G and Nile Blue dyes.

Reference: “FRET-assisted laser emission in colloidal suspensions of dye-doped latex nanoparticles,“ L. Cerdán,* E. Enciso, V. Martín, J. Bañuelos, I. Lopez Arbeloa, A. Costela and I. García-Moreno; Nature Photonics 2012 DOI: 10.1038/ NPHOTON.2012.201
http://www.nature.com/nphoton/journal/vaop/ncurrent/full/nphoton.2012.201.html

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FAF Life on Earth is based on nucleic acids that contain ribose (RNA) or deoxyribose (DNA) sugar moieties. However these are not the only polymers able to contain and transmit genetic information. It has been observed recently that, with the appropriated polymerases, nucleic acids based on other kind of sugars (such as arabinoses) can replicate.
So, why does nature use riboses? We do not know.
To help solve this problem, scientists from IQFR and McGill University in Montreal, funded by a CSIC I-link Project, have determined the structure of the “arabino nucleic acid” that it turned out to be very similar to our DNA.
Similar, but not identical. And the differences may be important, since they affect the stability of the double helix and other alternative structures. In addition, arabino-oligonucleotides and their fluoro-derivatives have very promising applications in biomedicine. In particular, they could prove very useful as they are resistant to ribonucleases, the enzymes which normally cleave and recycle nucleic acids, which in Earth have evolved to cleave nucleic acids based on ribose, but not in arabinose.
Referencia: The solution structure of double helical arabino nucleic acids (ANA and 2'F-ANA): effect of arabinoses in duplex-hairpin interconversion
Nerea Martin-Pintado et al., Nucleic Acids Res, 2012; doi: 10.1093/nar/gks672

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evolucion imanacion A cobalt film two atoms thick has a magnetization direction perpendicular to the film plane when grown on ruthenium. Spin-polarized low-energy electron microscopy allows to observe its local magnetization, and follow in real time and real space changes in the magnetic domains of the film. When exposed to minute amounts of hydrogen, the out-of-plane magnetic domains in the film first break into smaller domains and eventually the magnetization direction switches on an in-plane orientation. The effect is understood with theoretical calculations that show that the origin is the change in the electronic structure of the topmost cobalt atoms bonded to hydrogen. This effect might be used to make gas sensors based on magnetic detection. The hydrogen pressure required for the effect is just one billionth of the atmospheric pressure, for a few minutes. Given the prevalence of hydrogen in ultra-high-vacuum experimental instruments, this effect also points to the risk hydrogen effects can pose for magnetization studies.
Reference: B. Santos, S. Gallego, A. Mascaraque, K.F. McCarty, A. Quesada, A.T. N’Diaye, A.K. Schmid, and J. de la Figuera. "Hydrogen-induced reversible spin-reorientation transition and magnetic stripe domain phase in bilayer Co on Ru(0001)", Phys. Rev. B 85 (2012) 134409, DOI: 10.1103/PhysRevB.85.134409 (arxiv 1203.3945)

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Graphene peq

A team at the Institute of Physical Chemistry "Rocasolano" in Madrid predicts that graphene – a layer of carbon just one atom thick – could be used to create a perfect absorber of light if it is doped and patterned into a periodic array. The work could lead to improved light-detection devices, particularly in the infrared part of the electromagnetic spectrum, where current technologies struggle to function.

Reference:Complete Optical Absorption in Periodically Patterned Graphene

http://physics.aps.org/articles/v5/12
http://nanotechweb.org/cws/article/tech/48463
http://physicsworld.com/cws/article/news/48464