Triphenylamine- and triazine- containing hydrogen bonded complexes: liquid crystalline supramolecular semiconductors

Despite the fact that triphenylamine derivatives have been widely explored as hole-transporting materials, studies on charge transport properties in the liquid crystal phase have been overlooked. Here, it is reported that triphenylamine liquid crystals can attain very high hole mobility values in a hexagonal columnar mesophase, up toµ˜ 5 cm2V-1s-1. The columnar liquid crystalline phase was obtained by a proper design of a supramolecular mesogen, and this is unprecedented for triphenylamine liquid crystals. In fact, the supramolecules were formed by hydrogen-bonded 1¿:¿3 complexes of a star-shaped triazine core and three triphenylamine peripheral units. The resulting hexagonal columnar mesophase acts as a successful scaffold that confines TPA units at the periphery of columns. Challenging DFT theoretical investigations into a model based on such supramolecular systems involving a large number of atoms were undertaken to explore the stability and geometry of the complexes and their electronic properties

El valor del idioma español en ciencia y tecnología

Se analiza el valor del español como idioma principal en las revistas científicas editadas en España y en los países latinoamericanos, así como a través de la producción científica mundial recogida en las principales bases de datos bibliográficas de cobertura internacional. El estudio evidencia la importancia del español como lengua de comunicación científica en determinados ámbitos disciplinares ligados, por una parte, a intereses socioeconómicos y territoriales de los países de habla española, como es el caso de la economía regional, la medicina clínica, la geología y medio ambiente y, por otra, a determinados ámbitos científicos propios de las humanidades, como la literatura, la historia de los países iberoamericanos, etc. Este estudio pretende contribuir al mejor conocimiento y comprensión del valor real y potencial del español en la ciencia, de cara a la adecuada utilización de este recurso para el desarrollo de nuestras sociedades y su proyección cultural y económica a escala internacional.We analyse the specific weight of the Spanish as a primary language in scientific journals published in Spain and Latin American countries, as well as through the global scientific output covered by the main bibliographic databases of international coverage. The study highlights the importance of the Spanish as a language of scientific communication in certain disciplinary areas linked on the one hand to socio-economic regional interests of Spanish-speaking countries, as it is the case of Clinical medicine, Geology and Environment, and, on the other, to certain scientific fields of the Social sciences and Humanities, as it is the case of the Regional economy, the Literature, the History of Ibero-American countries, etc. This study aims to contribute to the better knowledge and understanding of the real and potential value of the Spanish in the scientific world, with regard to the appropriate use of this resource for the development of our societies, and its cultural and economic projection at the international level

RNA Methylation by the MIS Complex Regulates a Cell Fate Decision in Yeast

For the yeast Saccharomyces cerevisiae, nutrient limitation is a key developmental signal causing diploid cells to switch from yeast-form budding to either foraging pseudohyphal (PH) growth or meiosis and sporulation. Prolonged starvation leads to lineage restriction, such that cells exiting meiotic prophase are committed to complete sporulation even if nutrients are restored. Here, we have identified an earlier commitment point in the starvation program. After this point, cells, returned to nutrient-rich medium, entered a form of synchronous PH development that was morphologically and genetically indistinguishable from starvation-induced PH growth. We show that lineage restriction during this time was, in part, dependent on the mRNA methyltransferase activity of Ime4, which played separable roles in meiotic induction and suppression of the PH program. Normal levels of meiotic mRNA methylation required the catalytic domain of Ime4, as well as two meiotic proteins, Mum2 and Slz1, which interacted and co-immunoprecipitated with Ime4. This MIS complex (Mum2, Ime4, and Slz1) functioned in both starvation pathways. Together, our results support the notion that the yeast starvation response is an extended process that progressively restricts cell fate and reveal a broad role of post-transcriptional RNA methylation in these decisions

Evidence of a dual function in fl(2)d, a gene needed for Sex-lethal expression in Drosophila melanogaster.

Abstract In Drosophila melanogaster, the female sexual development of the soma and the germline requires the activity of the gene Sxl. The somatic cells need the function of the gene fl(2)d to follow the female developmental pathway, due to its involvement in the female-specific splicing of Sxl RNA. Here we report the analysis of both fl(2)d1 and fl(2)d2 mutations: (1) fl(2)d1 is a temperature-sensitive mutation lethal in females and semilethal in males; (2) fl(2)d2 is lethal in both sexes; (3) the fl(2)d1/fl(2)d2 constitution is temperature-sensitive and lethal in females, while semilethal in males. The temperature-sensitive period of fl(2)d1 in females expands the whole development. SxlM1 partially suppresses the lethality of fl(2)d1 homozygous females and that of fl(2)d1/fl(2)d2 constitution, whereas it does not suppress the lethality of fl(2)d2 homozygous females. The addition of extra Sxl+ copies does not increase the suppression effect of SxlM1. The fl(2)d1 mutation in homozygosis and the fl(2)d1/fl(2)d2 constitution, but not the fl(2)d2 in homozygosis, partially suppress the lethality of SxlM1 males. This suppression is not prevented by the addition of extra Sxl+ copies. The semilethality of both fl(2)d1 and fl(2)d1/fl(2)d2 males, and the lethality of fl(2)d2 males, is independent of Sxl function. There is no female synergistic lethality between mutations at fl(2)d and neither at sc or da. However, the female synergistic lethality between mutations at Sxl and either sc or da is increased by fl(2)d mutations. We have analyzed the effect of the fl(2)d mutations on the germline development of both females and males. For that purpose, we carried out the clonal analysis of fl(2)d1 in the germline. In addition, pole cells homozygous for fl(2)d2 were transplanted into wild-type host embryos, and we checked whether the mutant pole cells were capable of forming functional gametes. The results indicated that fl(2)d mutant germ cells cannot give rise to functional oocytes, while they can form functional sperm. Moreover, SxlM1 suppresses the sterility of the fl(2)d1 homozygous females developing at the permissive temperature. Thus, with respect to the development of the germline the fl(2)d mutations mimic the behavior of loss-of-function mutations at the gene Sxl. Females double heterozygous for fl(2)d and snf1621 are fully viable and fertile. fl(2)d2 in heterozygosis partially suppresses the phenotype of female germ cells homozygous for snf1621; however, this is not the case with the fl(2)d1 mutation. The fl(2)d mutations partially suppress the phenotype of the female germ cells homozygous for ovoDIrSI.(ABSTRACT TRUNCATED AT 400 WORDS)</jats:p

Dosage compensation in sciarids is achieved by hypertranscription of the single X chromosome in males.

Abstract Dosage compensation refers to the process whereby females and males with different doses of sex chromosomes have similar amounts of products from sex chromosome-linked genes. We analyzed the process of dosage compensation in Sciara ocellaris, Diptera of the suborder Nematocera. By autoradiography and measurements of X-linked rRNA in females (XX) and males (XO), we found that the rate of transcription of the single X chromosome in males is similar to that of the two X chromosomes in females. This, together with the bloated appearance of the X chromosome in males, support the idea that in sciarids dosage compensation is accomplished by hypertranscription of the X chromosome in males.</jats:p