169 research outputs found
X Inactivation Lessons from Differentiating Mouse Embryonic Stem Cells
No full textX chromosome inactivation (XCI) is the dosage compensation mechanism that evolved in female mammals to correct the genetic imbalance of X-linked genes between sexes. X chromosome inactivation occurs in early development when one of the two X chromosomes of females is nearly-completely silenced. Differentiating Embryonic Stem cells (ESC) are regarded as a useful tool to study XCI, since they recapitulate many events occurring during early development. In this review we aim to summarise the advances in the field and to discuss the close connection between cell differentiation and X chromosome inactivation, with a particular focus on mouse ESCs
Cosme de Aldana traduttore, adattatore e imitatore di sé stesso fra le "Rime" e i "sonetos" (Milano 1587)
No full textMarinetti si rivolge agli spagnoli: note al "Proclama futurista" (1910)tradotto da Ramón Gómez de la Serna
No full textSolution equilibria in YbDOTMA, a chiral analogue of one of the most successful contrast agents for MRI, GdDOTA
No full textThe structure and the conformational equilibria in aqueous and methanolic solutions of YbDOTMA (DOTMA = (1R,4R,7R,10R)-alpha,alpha',alpha",alpha""-tetramethyl-1,4,7,10-tetraaza- cyclododecane-1,4,7,10-tetraacetic acid) are investigated and the dynamics studied by means of NMR methods. The presence of two isomeric forms in slow exchange is confirmed and quantitatively characterized by EXSY. The exchange peaks are assigned to the inversion of the conformation of the macrocycle ring. No evidence is obtained of a reorientation of the methyl acetate substituents. The protons switch between positions with the same geometrical factors, i.e. positions that would have the same pseudocontact shifts were it not for the different magnetic susceptibility anisotropies of the two species; steady-state NOE spectra on the major form allow unequivocal assignment of the conformations of the two isomers
Function by structure: Spotlights on xist long non-coding RNA
No full textRecent experimental evidence indicates that lncRNAs can act as regulatory molecules in the context of development and disease. Xist, the master regulator of X chromosome inactivation, is a classic example of how lncRNAs can exert multi-layered and fine-tuned regulatory functions, by acting as a molecular scaffold for recruitment of distinct protein factors. In this review, we discuss the methodologies employed to define Xist RNA structures and the tight interplay between structural clues and functionality of lncRNAs. This model of modular function dictated by structure, can be also generalized to other lncRNAs, beyond the field of X chromosome inactivation, to explain common features of similarly folded RNAs
Stereoselection in the Binding of Ln DOTA to gamma-Cyclodextrin: A Near Infrared Circular Dichroism Study
No full textThe formation of an inclusion complex between gamma-cyclodextrin and Ln DOTA has been reported in the literature. All Ln DOTA complexes in solution give rise to a network of equilibria between different stereoisomers, which are pairs of enantiomers. By means of near infrared circular dichroism of the Yb derivative, we demonstrate that upon the formation of the host-guest complex, there is a complete stereoselection and that only the Lambda (delta delta delta delta) binds. Chirality 22:E11-E16, 2010
Stereochemistry and Near-Infrared Circular Dichroism of a Chiral Yb Complex
No full textThe near-infrared CD spectrum of ytterbium complexed by DOTMA, [DOTMA = (1R,4R,7R, 10R)-alpha, alpha', alpha ", alpha'''-tetramethyl-1,4,7, 10-tetraazacyclododecane-1,4,7,10-tetraacetic acid)] is presented. This is the first report of a near-infrared CD spectrum in solution of the f-f transitions of ytterbium in a complex whose solution structure and dynamics are completely defined. The spectrum shows several well-resolved transitions around 980 nm with very high dissymmetry factors. In water and in methanol, there are two diastereomeric conformations of YbDOTMA in equilibrium, Lambda(delta delta delta delta) or n and Lambda(lambda lambda lambda lambda) or p, being the latter always in a large excess. The relative proportion depends on temperature and solvent composition, but the CD spectrum is rather insensitive to these parameters, which demonstrates that neglecting the minor form contribution is an acceptable approximation. On lowering the temperature, the presence of hot bands is highlighted, which leads to a tentative assignment of the transitions. The absorption counterpart compares very well with that of YbDOTA, an achiral analogue, largely studied and well understood
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