Papers by Miguel Angel Torres
Nanomaterials, 2020
Attrition milling is an easily scalable and environmentally friendly process used to produce Ca3C... more Attrition milling is an easily scalable and environmentally friendly process used to produce Ca3Co4O9+δ nanoprecursors in a relatively short time. Sintered materials produced through the classical solid-state method, involving ball milling, show much larger grain sizes and slightly lower density than those obtained in samples produced from attrition-milled precursors. On the other hand, electrical resistivity has been drastically decreased, accompanied with a slight decrease in the Seebeck coefficient in samples obtained from these attrition-milled precursors. Moreover, the use of an attrition milling process leads to a very important reduction in processing time (around 75%), together with a slight power factor improvement of around 10%, when compared to the classically prepared samples.
Genetics, 1991
We have isolated three female-specific lethal mutations at the gene Sex-lethal (Sxl): Sxlfb, Sxlf... more We have isolated three female-specific lethal mutations at the gene Sex-lethal (Sxl): Sxlfb, Sxlfc and Sxlfd. We have carried out the complementation analysis between these mutations and other previously reported Sxlf mutations. It is possible to classify the alleles tested in this report into two complementation groups: the bc group defined by Sxlfb, and Sxlfc, and the LS group defined by SxlfLS. The other alleles tested affect both complementation groups albeit with different degrees. Contrary to what happens with mutations at the LS group, mutations at the bc group do not affect sex determination, nor late dosage compensation nor oogenesis. Both Sxlfb and Sxlfc present a DNA insertion of at least 5 kb between position -10 and -11 on the molecular map, within the fourth intron. On the contrary, Sxlfd, a strong mutation affecting all Sxl functions, is not associated to any detectable DNA alteration in Southern blots, so that it seems to be a "point" mutation. In agreement...
European Journal of Soil Science, 2020
Soil microorganisms surviving in mining sites have developed metal‐resistance mechanisms to biotr... more Soil microorganisms surviving in mining sites have developed metal‐resistance mechanisms to biotransform metals. Their use as biofertilizers can improve phytoremediation efficiency in contaminated soils by reducing metal toxicity while promoting plant growth. We analysed through whole‐metagenome shotgun sequencing the composition, diversity and function of microbial communities present in a contaminated mine soil along a gradient of metals (As, Cu, Fe, Mn, Pb, Zn) to identify tolerant species carrying metal‐resistance functional genes that can be used in association with plants for phytoremediation. Soil samples were collected from an abandoned copper mine, across three areas with different levels of metal contamination (unaffected, moderately contaminated and highly contaminated). The relative abundance of Proteobacteria, especially genus Bradyrhizobium, increased in the highly contaminated area, whereas Actinobacteria dominated in the unaffected area. Archaea (Euryarchaeota) predo...
Genome Biology, 2000
Positive and negative selection for unlinked transposition has been used to generate a large coll... more Positive and negative selection for unlinked transposition has been used to generate a large collection of Arabidopsis transposon lines. Significance and context Insertional mutagens such as T-DNAs (from Agrobacterium tumefaciens) and transposons are powerful tools for both 'forward' and 'reverse' genetic screens in Arabidopsis. Whereas the forward genetic approach starts with genes identified by mutation, reverse genetics involves screening for mutations in a given DNA sequence. Large collections of T-DNA insertion lines exist, but these often harbor complex and/or multiple insertions. Transposons offer the advantage that excision can cause reversion of the mutant phenotype or create new mutant alleles. Transposons, however, are unstable in the presence of their transposase and tend to move to linked sites, rendering genome-wide coverage difficult. To select for transposition events further from the insertion site and for loss of the transposase after transposon reinsertion, an elegant technique based on positive and negative selection has been designed by Rob Martienssen's group. The study by Tissier et al. presents a different version of positive/ negative selection that can be used for large-scale mutagenesis. A large library of lines with single, stable inserts was tested in reverse genetic screens, and 1,200 insertion sites were sequenced.
Boletín de la Sociedad Española de Cerámica y Vidrio, 2019
Bi 2 Sr 2−x K x Co 2 O y (x = 0.0, 0.025, 0.050, 0.075, 0.100, 0.125, and 0.15) ceramic materials... more Bi 2 Sr 2−x K x Co 2 O y (x = 0.0, 0.025, 0.050, 0.075, 0.100, 0.125, and 0.15) ceramic materials have been fabricated using a classical ceramic process, followed by texturing through directional solidification. SEM analysis of samples, before and after annealing has shown that grains were aligned along the growth direction. While as-grown samples have several phases, besides the thermoelectric one, the annealed ones show much higher thermoelectric phase content. In addition, K-substitution increases the thermoelectric phase content and enhances grain orientation. These improvements decrease the electrical resistivity without significant changes in Seebeck coefficient. The maximum power factor value for 0.10K-substituted annealed samples has been found as 0.20 mW/K 2 m. This is superior to the highest reported for hot-pressed materials. However, all samples have similar magnetic properties.
Materials, 2018
In this study, Ca0.9Yb0.1MnO3 + x wt.% Ag (with x = 0, 1, 3, 5, and 10) thermoelectric materials ... more In this study, Ca0.9Yb0.1MnO3 + x wt.% Ag (with x = 0, 1, 3, 5, and 10) thermoelectric materials were prepared via the classical ceramic method. In spite of the very high sintering temperature (1300 °C), no significant Ag losses were observed following this process. Moreover, Ag addition enhanced cation mobility during sintering due to the formation of a liquid phase. Microstructurally, it was found that Ag decreases porosity; this was confirmed by density measurements. Ag was also found to promote the formation of a Ca2Mn2O5 secondary phase. Despite the presence of this secondary phase, samples with Ag displayed lower electrical resistivity than Ag-free ones, without a drastic decrease in the absolute Seebeck coefficient. The highest thermoelectric performances, which were determined by power factor, were obtained in 1 wt.% Ag samples. These maximum values are slightly higher than the best of those reported in the literature for sintered materials with similar compositions, with th...
The Plant journal : for cell and molecular biology, Jan 19, 2018
Codeinone reductase (COR) catalyzes the reversible NADPH-dependent reduction of codeinone to code... more Codeinone reductase (COR) catalyzes the reversible NADPH-dependent reduction of codeinone to codeine as the penultimate step of morphine biosynthesis in opium poppy (Papaver somniferum). COR also irreversibly reduces neopinone, which forms by spontaneous isomerization in aqueous solution from codeinone, to neopine. In a parallel pathway involving 3-O-desmethylated analogs, COR converts morphinone to morphine, and neomorphinone to neomorphine. Similar to neopine, neomorphine formation by COR is irreversible. Neopine is a minor substrate for codeine O-demethylase (CODM) yielding morphine. In the plant, neopine levels are low and neomorphine has not been detected. Silencing of CODM leads to accumulation of upstream metabolites, such as codeine and thebaine, but does not result in a shift towards higher relative concentrations of neopine, suggesting a plant mechanism for limiting neopine production. In yeast (Saccharomyces cerevisiae) engineered to produce opiate alkaloids, the catalyti...
The Journal of biological chemistry, Jan 29, 2016
Benzylisoquinoline alkaloids (BIAs) are produced in a wide variety of plants and include many com... more Benzylisoquinoline alkaloids (BIAs) are produced in a wide variety of plants and include many common analgesic, antitussive and anticancer compounds. Several members of a distinct family of S-adenosylmethionine (SAM)-dependent N-methyltransferases (NMTs) play critical roles BIA biosynthesis, but, the molecular basis of substrate recognition and catalysis are not known for NMTs involved in BIA metabolism. To address this issue, the crystal structure of pavine NMT (PavNMT) from Thalictrum flavum was solved using selenomethionine-substituted protein (dmin = 2.8 Å). Additional structures were determined for the native protein (dmin = 2.0 Å), as well as binary complexes with SAM (dmin = 2.3 Å) or the reaction product S-adenosylhomocysteine (SAH) (dmin = 1.6 Å). The structure of a complex with SAH and two molecules of tetrahydropapaverine (THP, one as the S conformer and a second in the R configuration) (dmin = 1.8 Å) revealed key features of substrate recognition. PavNMT converted racemi...
Verbo Revista De Formacion Civica Y De Accion Cultural Segun El Derecho Natural Y Cristiano, 2009
El 24 de nov i e m b re pasado, a los setenta y tres años, tras larga y penosa enfermedad, moría ... more El 24 de nov i e m b re pasado, a los setenta y tres años, tras larga y penosa enfermedad, moría nuestro amigo Francesco Gentile en su casa de Piazza Capitaniato, en el centro de la ciudad de Pa d u a. Nacido en una familia de tradición intelectual, su padre fue el filósofo triestino Marino Gentile, fundador de la conocida como escuela filosófica patavina, re n ovadora de los estudios aristotélicos, y sin la menor relación con otro Gentile famoso, de nombre Gi ovanni. Tras estudiar derecho en la Un i versidad de Padua, con m a e s t ros del re l i e ve de Enrico Op o c h e r, Alberto Tr a b u c c h i , Giuseppe Bettiol o Gaetano Arangio Ruiz, Francesco sintió y siguió también la vocación intelectual. Muy pronto, en 1958, fue asistente en una cátedra de su alma mater y, tras habilitarse en 1965, docente durante más de cuarenta años en las Facultades de De recho o de Letras de Trento, Pe rusa, Nápoles, Catanzaro o, s o b re todo, Padua. Catedrático de Filosofía del De recho fue también decano, en dos ocasiones,
Acta Materialia, 2016
Bi 2 Ca 2 Co 1.7 O x thermoelectric ceramics with small Ag additions (0, 1, 2, 3, 4, and 5 wt.%) ... more Bi 2 Ca 2 Co 1.7 O x thermoelectric ceramics with small Ag additions (0, 1, 2, 3, 4, and 5 wt.%) have been successfully grown from the melt, using the laser floating zone method and subsequently annealed at 800 ºC for 24 h. The microstructure has shown a reduction of the amount of secondary phases for Ag contents up to 4 wt.%. This microstructural evolution leads to a decrease of the electrical resistivity values until an Ag content of 4 wt.%, whereas Seebeck coefficient has been maintained unchanged. This is in agreement with the presence of metallic Ag in all samples, confirmed not only by Energy Dispersive Spectrometry but also by X-ray photoelectron and Auger spectroscopy. These electrical properties lead to maximum power factor values of about 0.30 mW/K 2 .m at 650 ºC for the 4 wt.% Ag containing samples, which is among the best results obtained for this type of materials.
Revista Española de Cardiología, 2010
ZooKeys, 2012
A new genus of cynipid oak gallwasp, Zapatella Pujade-Villar & Melika, gen. n. (Hymenoptera: Cyni... more A new genus of cynipid oak gallwasp, Zapatella Pujade-Villar & Melika, gen. n. (Hymenoptera: Cynipidae: Cynipini), with two new species, Zapatella grahami Pujade-Villar & Melika, sp. n. and Z. nievesaldreyi Melika & Pujade-Villar, sp. n., is described from the Neotropics. Zapatella grahami, known only from the sexual generation, induces galls in acorns of Quercus costaricensis and is currently known only from Costa Rica. Zapatella nievesaldreyi, known only from the asexual generation, induces inconspicuous galls in twigs of Q. humboldtii, and is known only from Colombia. Diagnostic characters for both new species are given in detail. Five Nearctic species are transferred from Callirhytis to Zapatella: Z. cryptica (Weld), comb. n., Z. herberti (Weld), comb. n., Z. oblata (Weld), comb. n., Z. quercusmedullae (Ash
The Journal of cell biology, 1996
When overexpressed in Xenopus embryos, Xwnt-1, -3A, -8 and -8b define a functional class of Wnts ... more When overexpressed in Xenopus embryos, Xwnt-1, -3A, -8 and -8b define a functional class of Wnts (the Wnt-1 class) that promotes duplication of the embryonic axis, whereas Xwnt-5A, -4, and -11 define a distinct class (the Wnt-5A class) that alters morphogenetic movements (Du, S., S. Purcell, J. Christian, L. McGrew, and R. Moon. 1995. Mol. Cell. Biol. 15:2625-2634). Since come embryonic cells may be exposed to signals from both functional classes of Wnt during vertebrate development, this raises the question of how the signaling pathways of these classes of Wnts might interact. To address this issue, we coexpressed various Xwnts and components of the Wnt-1 class signaling pathway in developing Xenopus embryos. Members of the Xwnt-5A class antagonized the ability of ectopic Wnt-1 class to induce goosecoid expression and a secondary axis. Interestingly, the Wnt-5A class did not block goosecoid expression or axis induction in response to overexpression of cytoplasmic components of the ...
The Journal of Cell Biology, 1997
Eggs of Xenopus laevis undergo a postfertilization cortical rotation that specifies the position ... more Eggs of Xenopus laevis undergo a postfertilization cortical rotation that specifies the position of the dorso-ventral axis and activates a transplantable dorsal-determining activity in dorsal blastomeres by the 32-cell stage. There have heretofore been no reported dorso-ventral asymmetries in endogenous signaling proteins that may be involved in this dorsal-determining activity during early cleavage stages. We focused on β-catenin as a candidate for an asymmetrically localized dorsal-determining factor since it is both necessary and sufficient for dorsal axis formation. We report that β-catenin displays greater cytoplasmic accumulation on the future dorsal side of the Xenopus embryo by the two-cell stage. This asymmetry persists and increases through early cleavage stages, with β-catenin accumulating in dorsal but not ventral nuclei by the 16- to 32cell stages. We then investigated which potential signaling factors and pathways are capable of modulating the steady-state levels of en...
Proceedings of the National Academy of Sciences, 1997
Catenins are proteins associated with the cytoplasmic domain of cadherins, a family of transmembr... more Catenins are proteins associated with the cytoplasmic domain of cadherins, a family of transmembrane cell adhesion molecules. The cadherin–catenin adhesion system is involved in morphogenesis during development and in the maintenance of the integrity of different tissue types. Using a gene trap strategy, we have isolated a mouse mutation for the gene encoding the α-E-catenin. This form of the α-catenin appears frequently coexpressed with E-cadherin in epithelial cell types. The mutation obtained eliminates the carboxyl-terminal third of the protein but nevertheless provokes a complete loss-of-function phenotype. Homozygous mutants show disruption of the trophoblast epithelium (the first differentiated embryonic tissue), and development is consequently blocked at the blastocyst stage. This phenotype parallels the defects observed in E-cadherin mutant embryos. Our results show the requirement of the α-E-catenin carboxy terminus for its function and represent evidence of the role of th...
Molecular Immunology, 2009
The identification of potential allergenic proteins is usually done by scanning a database of all... more The identification of potential allergenic proteins is usually done by scanning a database of allergenic proteins and locating known allergens with a high sequence similarity. However, there is no universally accepted cutoff value for sequence similarity to indicate potential IgE cross-reactivity. Further, overall sequence similarity may be less important than discrete areas of similarity in proteins with homologous structure. To identify such areas, we first classified all allergens and their subdomains in the Structural Database of Allergenic Proteins (SDAP, http://fermi.utmb.edu/SDAP/) to their closest protein families as defined in Pfam, and identified conserved physicochemical property motifs characteristic of each group of sequences. Allergens populate only a small subset of all known Pfam families, as all allergenic proteins in SDAP could be grouped to only 130 (of 9318 total) Pfams, and 31 families contain more than four allergens. Conserved physicochemical property motifs for the aligned sequences of the most populated Pfam families were identified with the PCPMer program suite and catalogued in the webserver Motif-Mate (http://born.utmb.edu/motifmate/summary.php). We also determined specific motifs for allergenic members of a family that could distinguish them from non-allergenic ones. These allergen specific motifs should be most useful in database searches for potential allergens. We found that sequence motifs unique to the allergens in three families (seed storage proteins, Bet v 1, and tropomyosin) overlap with known IgE epitopes, thus providing evidence that our motif based approach can be used to assess the potential allergenicity of novel proteins.
Mechanisms of Development, 1997
In Drosophila the decision processes between the neural and epidermal fate for equipotent ectoder... more In Drosophila the decision processes between the neural and epidermal fate for equipotent ectodermal cells depend on the activity of proneural genes. Members of the Drosophila Iroquois-Complex (Iro-C) positively regulate the activity of certain proneural AS-C genes during the formation of external sensory organs. We have identified and characterized three mouse Iroquois-related genes: Irx1,-2 and-3, which have a homeodomain very similar to that of the Drosophila Iro-C genes. The sequence similarity implies that these three genes represent a separate homeobox family. All three genes are expressed with distinct spatio/temporal patterns during early mouse embryogenesis. These patterns implicate them in a number of embryonic developmental processes: the A/P and D/V patterning of specific regions of the central nervous system (CNS), and regionalization of the otic vesicle, branchial epithelium and limbs.
Glia, 2008
Astrocytes respond to central nervous system (CNS) injury with reactive astrogliosis and particip... more Astrocytes respond to central nervous system (CNS) injury with reactive astrogliosis and participate in the formation of the glial scar, an inhibitory barrier for axonal regeneration. Little is known about the injury-induced mechanisms underlying astrocyte reactivity and subsequent development of an axon-inhibitory scar. We combined two key aspects of CNS injury, mechanical trauma and co-culture with meningeal cells, to produce an in vitro model of the scar from cultures of highly differentiated astrocytes. Our model displayed widespread morphological signs of astrocyte reactivity, increases in expression of glial fibrillary acidic protein (GFAP), and accumulation of GFAP in astrocytic processes. Expression levels of scar-associated markers phosphacan, neurocan and tenascins were also increased. Importantly, neurite growth from various CNS neuronal populations was significantly reduced when neurons were seeded on the scar-like cultures, compared to growth on cultures of mature astrocytes. Quantification of neurite growth parameters on the scar model demonstrated significant reductions in neuronal adhesion and neurite lengths. Interestingly, neurite outgrowth of postnatal neurons was reduced to a greater extent than that of embryonic neurons, and outgrowth inhibition varied among neuronal populations. Scar-like reactive sites and neurite-inhibitory patches were found throughout these cultures, creating a patchwork of growth-inhibitory areas mimicking a CNS injury site. Thus, our model showed relevant aspects of scar formation and produced widespread inhibition of axonal regeneration; it should be useful both for examining mechanisms underlying scar formation and to assess various treatments for their potential to improve regeneration after CNS injury.
Experimental Cell Research, 1998
We have used different gene trap vectors and in vitro preselection of embryonic stem (ES) cells f... more We have used different gene trap vectors and in vitro preselection of embryonic stem (ES) cells for a large scale screening of insertional mutations in developmentally regulated genes. A gene trap vector was constructed, which contains an internal ribosome entry site (IRES) upstream from a geo selectable-reporter fusion gene. Analysis of 801 independent integrations revealed that the IRESgeo vector allows for a global enrichment of about 15 folds in the number of detectable gene trap events when compared with a conventional geo vector. Characterization of in vitro and in vivo lacZ expression suggested that this IRES-based vector is able to capture a wide range of genes expressed in a variety of tissues and developmental stages, and it can also allow trapping of genes expressed at very low levels in ES cells. A preselection protocol was devised, where gene-trapped ES cells were grown in the presence of specific growth/differentiation factors such as follistatin, nerve growth factor, and retinoic acid. Several gene trap integrations were found to be either activated or repressed by one of these factors. Characterization of lacZ expression during embryogenesis showed a strong enrichment of restricted patterns in vivo after ES cell preselection. These results suggest that a combination of IRESgeo vector and in vitro preselection is more effective for the capture and mutation of a large number of developmental genes.
Uploads
Papers by Miguel Angel Torres