Knowledge and attitudes of French and Israeli 12th graders in agricultural or rural secondary schools about water and irrigation related issues

In arid countries, the use of water by agriculture raises important social. economic. and moral issues. This study attempted to compare the knowledge and attitudes of agricultural secondary schools 12th graders in Israel (essentially a Mediterranean arid or semi-arid country) with those of comparable students in France, a country where water is not a central limiting factor in agriculture, concerning six aspects of the use and misuse of water by agriculture. Students were required to assess the desirability of existing situations, the possibility to change them, and the potential influence of five factors of change (scientific knowledge, government authorities, social customs, laws of economics, and the individual citizen). The Israeli students systematically put a strong emphasis on scientific knowledge and authorities. The reactions of the French students were weaker than those of the Israelis. Also, there were only two aspects in which they considered that any of the factors could have a significant influence. And finally, the individual citizen, and not scientific knowledge or authorities, was regarded by the French students to be the potentially most influential factor - actually the only one.peer-reviewe

Thermal difference spectra: a specific signature for nucleic acid structures

We show that nucleic acid structures may be conveniently and inexpensively characterized by their UV thermal difference spectra. A thermal difference spectrum (TDS) is obtained for a nucleic acid by simply recording the ultraviolet absorbance spectra of the unfolded and folded states at temperatures above and below its melting temperature (T(m)). The difference between these two spectra is the TDS. The TDS has a specific shape that is unique for each type of nucleic acid structure, a conclusion that is based on a comparison of >900 spectra from 200 different sequences. The shape of the TDS reflects the subtleties of base stacking interactions that occur uniquely within each type of nucleic acid structure. TDS provides a simple, inexpensive and rapid method to obtain structural insight into nucleic acid structures, which is applicable to both DNA and RNA from short oligomers to polynucleotides. TDS complements circular dichroism as a tool for the structural characterization of nucleic acids in solution

Kinetics of tetramolecular quadruplexes

The melting of tetramolecular DNA or RNA quadruplexes is kinetically irreversible. However, rather than being a hindrance, this kinetic inertia allows us to study association and dissociation processes independently. From a kinetic point of view, the association reaction is fourth order in monomer and the dissociation first order in quadruplex. The association rate constant k(on), expressed in M(−3)·s(−1) decreases with increasing temperature, reflecting a negative activation energy (E(on)) for the sequences presented here. Association is favored by an increase in monocation concentration. The first-order dissociation process is temperature dependent, with a very positive activation energy E(off), but nearly ionic strength independent. General rules may be drawn up for various DNA and RNA sequence motifs, involving 3–6 consecutive guanines and 0–5 protruding bases. RNA quadruplexes are more stable than their DNA counterparts as a result of both faster association and slower dissociation. In most cases, no dissociation is found for G-tracts of 5 guanines or more in sodium, 4 guanines or more in potassium. The data collected here allow us to predict the amount of time required for 50% (or 90%) quadruplex formation as a function of strand sequence and concentration, temperature and ionic strength

Genèse de l’Observatoire du Patrimoine et de la Culture Scientifiques et Techniques

L’OCIM a reçu une nouvelle mission : celle d’un Observatoire du Patrimoine et de la Culture Scientifiques et Techniques. Partant d’une interrogation sur la définition d’un observatoire, cet article présente les premières réflexions et pistes de travail qui animent la gestation de ce nouveau dispositif, au service des acteurs de ce champ spécifique.L’OCIM has been doted with a new mission: that of being a Heritage and Scientific Culture Observatory. Stemming from a wish to define what an observatory is, this article presents the initial ideas and ways to advance with the new entity that is available to all actors within this specific field through its gestation process

8-Amino guanine accelerates tetramolecular G-quadruplex formation

2 pages, 4 figures, 1 table.-- PMID: 18566727 [PubMed].We demonstrate here that 8-amino guanine (R) strongly accelerates quadruplex formation, which makes this nucleobase the most attractive replacement for guanine in the context of tetramolecular parallel quadruplexes.This work was supported by ARC (#3365 to J.L.M), and E.U. FP6 MolCancerMed (LSHC-CT-2004-502943) grants. We thank Elena Cubero (IRB, Barcelona) for preliminary MD/TI simulations.Peer reviewe

Involvement of G-quadruplex regions in mammalian replication origin activity.

Genome-wide studies of DNA replication origins revealed that origins preferentially associate with an Origin G-rich Repeated Element (OGRE), potentially forming G-quadruplexes (G4). Here, we functionally address their requirements for DNA replication initiation in a series of independent approaches. Deletion of the OGRE/G4 sequence strongly decreased the corresponding origin activity. Conversely, the insertion of an OGRE/G4 element created a new replication origin. This element also promoted replication of episomal EBV vectors lacking the viral origin, but not if the OGRE/G4 sequence was deleted. A potent G4 ligand, PhenDC3, stabilized G4s but did not alter the global origin activity. However, a set of new, G4-associated origins was created, whereas suppressed origins were largely G4-free. In vitro Xenopus laevis replication systems showed that OGRE/G4 sequences are involved in the activation of DNA replication, but not in the pre-replication complex formation. Altogether, these results converge to the functional importance of OGRE/G4 elements in DNA replication initiation

Author Correction: Involvement of G-quadruplex regions in mammalian replication origin activity

An amendment to this paper has been published and can be accessed via a link at the top of the paper

Sequence variant (CTAGGG)n in the human telomere favors a G-quadruplex structure containing a G·C·G·C tetrad

Short contiguous arrays of variant CTAGGG repeats in the human telomere are unstable in the male germline and somatic cells, suggesting formation of unusual structures by this repeat type. Here, we report on the structure of an intramolecular G-quadruplex formed by DNA sequences containing four human telomeric variant CTAGGG repeats in potassium solution. Our results reveal a new robust antiparallel G-quadruplex fold involving two G-tetrads sandwiched between a G·C base pair and a G·C·G·C tetrad, which could represent a new platform for drug design targeted to human telomeric DNA

Surviving Sepsis Campaign: International guidelines for management of severe sepsis and septic shock: 2008

SCOPUS: ar.jinfo:eu-repo/semantics/publishe