Suchergebnisse

[EN] Genomes contain rare guanine-rich sequences capable of assembling into four-stranded helical structures, termed G-quadruplexes, with potential roles in gene regulation and chromosome stability. Their mechanical unfolding has only been reported to date by all-atom simulations, which cannot dissect the major physical interactions responsible for their cohesion. Here, we propose a mesoscopic model to describe both the mechanical and thermal stability of DNA G-quadruplexes, where each nucleotide of the structure, as well as each central cation located at the inner channel, is mapped onto a single bead. In this framework we are able to simulate loading rates similar to the experimental ones, which are not reachable in simulations with atomistic resolution. In this regard, we present single-molecule force-induced unfolding experiments by a high-resolution optical tweezers on a DNA telomeric sequence capable of adopting a G-quadruplex conformation. Fitting the parameters of the model to the experiments we find a correct prediction of the rupture-force kinetics and a good agreement with previous near equilibrium measurements. Since G-quadruplex unfolding dynamics is halfway in complexity between secondary nucleic acids and tertiary protein structures, our model entails a nanoscale paradigm for non-equilibrium processes in the cell. ; Work supported by the Spanish Ministry of Economy and Competitiveness (MINECO), grant No. FIS2014-55867, co-financed by FEDER funds. We also thank the support of the Aragon Government and Fondo Social Europeo to FENOL group. Work in J.R.A.-G. laboratory was supported by a grant from MINECO, No. MAT2015-71806-R). ; Bergues-Pupo, A.; Gutiérrez, I.; Arias-Gonzalez, JR.; Falo, F.; Fiasconaro, A. (2017). Mesoscopic model for DNA G-quadruplex unfolding. Scientific Reports. 7:1-13. https://doi.org/10.1038/s41598-017-10849-2 ; S ; 1 ; 13 ; 7 ; Arias-Gonzalez, J. R. Single-molecule portrait of DNA and RNA double helices. Integr. Biol. 6, 904 (2014). ; Burge, S., Parkinson, G. N., Hazel, P., ...

TREASURE project aims to develop sustainable pork chains based on European local pig breeds. The Porc Negre Mallorquí (Majorcan Black Pig, MBP) is an untapped pig breed from Mallorca, in the Balearic Islands, included in the project due its high rusticity, adaptation to the environment and meat quality differentiation. Particularities of MBP are mostly unknown out from Mallorca, with only one representative meat product, the 'sobrassada de Mallorca de Porc Negre', a fatrich cured sausage owning a PGI trademark. Carcass, meat and fat quality of MBP was evaluated, according to a standardised toolbox of parameters. The toolbox aimed for a harmonised knowledge of untapped breeds, made from the contribution of researcher's expertise and the literature. The mean values and standard deviation for carcass traits (n=29) were: 156.8±11.8 kg for live weight, 125.3±12.9 kg for carcass weight, 75.1±3.2% for carcass dressing, 88.7±3.7 cm for carcass length and 55.2±10.1 mm for ZP fat. The most remarkable results for the meat quality parameters toolbox (n=58) were an ultimate pH of 5.58±0.12 and electrical conductivity of 6.99±3.44 mS, a lightness value (L*) of 44.10±3.59, a drip loss of 1.49±1.46%, a shear force of 3.46±1.07 kg, and an intramuscular fat (IMF) content of 6.11±3.09%. The maximum value of IMF was 19%, a hint of the wide variability within this untapped breed, representing a disadvantage for the product standardisation in case of fresh meat, but not for 'sobrassada', mainly made of grounded ham, shoulder and loin. The results for the major fatty acid (FA) groups in back fat (n=48) samples were 41.00±1.42% of saturated FA, 51.27±1.64% monounsaturated FA and 6.88±0.71% polyunsaturated FA. 'Sobrassada' includes 40-50% of back fat, thus the FA composition is critical for product quality. The FA composition, with a high proportion of MUFA and low of PUFA contributes to an optimal technological quality of MBP back fat. Funded by European Union's H2020 RIA program (grant agreement no. 634476).

[EN] To our knowledge, we have developed a novel temperature-jump optical tweezers setup that changes the temperature locally and rapidly. It uses a heating laser with a wavelength that is highly absorbed by water so it can cover a broad range of temperatures. This instrument can record several force-distance curves for one individual molecule at various temper- atures with good thermal and mechanical stability. Our design has features to reduce convection and baseline shifts, which have troubled previous heating-laser instruments. As proof of accuracy, we used the instrument to carry out DNA unzipping experi- ments in which we derived the average basepair free energy, entropy, and enthalpy of formation of the DNA duplex in a range of temperatures between 5 C and 50 C. We also used the instrument to characterize the temperature-dependent elasticity of single-stranded DNA (ssDNA), where we find a significant condensation plateau at low force and low temperature. Oddly, the persistence length of ssDNA measured at high force seems to increase with temperature, contrary to simple entropic models. ; The authors thank J. Camunas and S. Frutos for contributing the molecules used in the experiments, and J.M. Huguet for helpful discussion. F.R. is supported by grant Institucio Catalana de Recerca i Estudis Avancats Academia 2013 and J.R. A.-G. by an Explora grant from MINECO (MAT2013-49455-EXP). The research that led to the results presented here was funded by the European Union Seventh Framework Programme (FP7/2007-2013) under grant 308850 INFERNOS and European Research Council grant MagReps (No. 267862). ; De Lorenzo, S.; Ribezzi-Crivellari, M.; Arias-Gonzalez, JR.; Smith, S.; Ritort, F. (2015). A Temperature-Jump Optical Trap for Single-Molecule Manipulation. Biophysical Journal. 108(12):2854-2864. https://doi.org/10.1016/j.bpj.2015.05.017 ; S ; 2854 ; 2864 ; 108 ; 12