A theoretical study of elastic X-ray scattering

Bragg X-ray scattering intensities are defined as scattering by the thermodynamic average electron-charge density. Purely elastic, kinematic X-ray scattering by a target in thermal equilibrium is always larger than Bragg scattering. At low temperatures, the elastic scattering becomes Bragg scattering. For large molecules, such as a crystal, at ordinary temperatures the elastic and Bragg scattering differ in a relative sense by O(N-1), where N is the number of vibrational degrees of freedom. For most practical cases the Bragg scattering is essentially the same as purely elastic scattering of X-rays

Do prestigious Spanish scholarly book publishers have more teaching impact?

Purpose The purpose of this paper is to assess the educational value of prestigious and productive Spanish scholarly publishers based on mentions of their books in online scholarly syllabi. Design/methodology/approach Syllabus mentions of 15,117 books from 27 publishers were searched for, manually checked and compared with Microsoft Academic (MA) citations. Findings Most books published by Ariel, Síntesis, Tecnos and Cátedra have been mentioned in at least one online syllabus, indicating that their books have consistently high educational value. In contrast, few books published by the most productive publishers were mentioned in online syllabi. Prestigious publishers have both the highest educational impact based on syllabus mentions and the highest research impact based on MA citations. Research limitations/implications The results might be different for other publishers. The online syllabus mentions found may be a small fraction of the syllabus mentions of the sampled books. Practical implications Authors of Spanish-language social sciences and humanities books should consider general prestige when selecting a publisher if they want educational uptake for their work. Originality/value This is the first study assessing book publishers based on syllabus mentions

Involvement of Transcription Factor NR2F2 in Human Trophoblast Differentiation

differentiation of human villous cytotrophoblast (CTB) cells to a syncytiotrophoblast (STB) phenotype, mRNA levels for the nuclear hormone receptor NR2F2 (ARP-1, COUP-TFII) increase rapidly, reaching a peak at day 1 of differentiation that is 8.8-fold greater than that in undifferentiated CTB cells. To examine whether NR2F2 is involved in the regulation of villous CTB cell differentiation, studies were performed to determine whether NR2F2 regulates the expression of TFAP2A (AP-2α), a transcription factor that is critical for the terminal differentiation of these cells to a STB phenotype.Overexpression of NR2F2 in primary cultures of human CTB cells and JEG-3 human choriocarcinoma cells induced dose-dependent increases in TFAP2A promoter activity. Conversely, siRNA mediated silencing of the NR2F2 gene in villous CTB undergoing spontaneous differentiation blocked the induction of the mRNAs for TFAP2A and several STB cell specific marker genes, including human placental lactogen (hPL), pregnancy specific glycoprotein 1 (PSG1) and corticotropin releasing hormone (CRH) by 51–59%. The induction of TFAP2A promoter activity by NR2F2 was potentiated by the nuclear hormone receptors retinoic acid receptor alpha (RARA) and retinoid X receptor alpha (RXRA).Taken together, these results strongly suggest that NR2F2 is involved in villous CTB cell differentiation and that NR2F2 acts, at least in part, by directly activating TFAP2A gene expression and by potentiating the transactivation of TFAP2A by RARA and RXRA

Impairment of LTD and cerebellar learning by Purkinje cell–specific ablation of cGMP-dependent protein kinase I

The molecular basis for cerebellar plasticity and motor learning remains controversial. Cerebellar Purkinje cells (PCs) contain a high concentration of cGMP-dependent protein kinase type I (cGKI). To investigate the function of cGKI in long-term depression (LTD) and cerebellar learning, we have generated conditional knockout mice lacking cGKI selectively in PCs. These cGKI mutants had a normal cerebellar morphology and intact synaptic calcium signaling, but strongly reduced LTD. Interestingly, no defects in general behavior and motor performance could be detected in the LTD-deficient mice, but the mutants exhibited an impaired adaptation of the vestibulo-ocular reflex (VOR). These results indicate that cGKI in PCs is dispensable for general motor coordination, but that it is required for cerebellar LTD and specific forms of motor learning, namely the adaptation of the VOR

PR-SET7 and SUV4-20H regulate H4 lysine-20 methylation at imprinting control regions in the mouse

Imprinted genes are important in development and their allelic expression is mediated by imprinting control regions (ICRs). On their DNA-methylated allele, ICRs are marked by trimethylation at H3 Lys 9 (H3K9me3) and H4 Lys 20 (H4K20me3), similar to pericentric heterochromatin. Here, we investigate which histone methyltransferases control this methylation of histone at ICRs. We found that inactivation of SUV4-20H leads to the loss of H4K20me3 and increased levels of its substrate, H4K20me1. H4K20me1 is controlled by PR-SET7 and is detected on both parental alleles. The disruption of SUV4-20H or PR-SET7 does not affect methylation of DNA at ICRs but influences precipitation of H3K9me3, which is suggestive of a trans-histone change. Unlike at pericentric heterochromatin, however, H3K9me3 at ICRs does not depend on SUV39H. Our data show not only new similarities but also differences between ICRs and heterochromatin, both of which show constitutive maintenance of methylation of DNA in somatic cells