ALBERT

Description: An integrated continuous process, which combines catalytic distillation and extractive distillation in one column, is investigated for the synthesis of high-purity methylal from methanol and formalin in the presence of a cation-exchange resin catalyst. A feed with methanol:formaldehyde 2:1 molar ratio is chosen to evaluate the effects of operating parameters, such as extractant feeding position, ratio of extractant to feed, reflux ratio, and reboiler temperature, on the continuous synthesis of methylal. Under the optimum operating conditions and with water as extractant, the extractive catalytic distillation process operated continuously, producing a methylal purity of 98.7 % (H 2 O: 〈 1.30 %) with 98.0 % formaldehyde conversion. An integrated continuous process combining catalytic distillation and extractive distillation in one column is applied for high-purity methylal synthesis from methanol and formalin in the presence of a cation-exchange resin catalyst. Under optimum conditions, using water as extractant, the extractive catalytic distillation process provided a methylal purity of 98.7 % with 98.0 % formaldehyde conversion.

Description: An integrated continuous process, which combines catalytic distillation and extractive distillation in one column, is investigated for the synthesis of high-purity methylal from methanol and formalin in the presence of a cation-exchange resin catalyst. A feed with methanol:formaldehyde 2:1 molar ratio is chosen to evaluate the effects of operating parameters, such as extractant feeding position, ratio of extractant to feed, reflux ratio, and reboiler temperature, on the continuous synthesis of methylal. Under the optimum operating conditions and with water as extractant, the extractive catalytic distillation process operated continuously, producing a methylal purity of 98.7 % (H 2 O: 〈 1.30 %) with 98.0 % formaldehyde conversion. An integrated continuous process combining catalytic distillation and extractive distillation in one column is applied for high-purity methylal synthesis from methanol and formalin in the presence of a cation-exchange resin catalyst. Under optimum conditions, using water as extractant, the extractive catalytic distillation process provided a methylal purity of 98.7 % with 98.0 % formaldehyde conversion.

Description: Leber's hereditary optic neuropathy (LHON) is the most common mitochondrial disorder. Nuclear modifier genes are proposed to modify the phenotypic expression of LHON-associated mitochondrial DNA (mtDNA) mutations. By using an exome sequencing approach, we identified a LHON susceptibility allele (c.572G〉T, p.191Gly〉Val) in YARS2 gene encoding mitochondrial tyrosyl-tRNA synthetase, which interacts with m.11778G〉A mutation to cause visual failure. We performed functional assays by using lymphoblastoid cell lines derived from members of Chinese families (asymptomatic individuals carrying m.11778G〉A mutation, or both m.11778G〉A and heterozygous p.191Gly〉Val mutations and symptomatic subjects harboring m.11778G〉A and homozygous p.191Gly〉Val mutations) and controls lacking these mutations. The 191Gly〉Val mutation reduced the YARS2 protein level in the mutant cells. The aminoacylated efficiency and steady-state level of tRNA Tyr were markedly decreased in the cell lines derived from patients both carrying homozygous YARS2 p.191Gly〉Val and m.11778G〉A mutations. The failure in tRNA Tyr metabolism impaired mitochondrial translation, especially for polypeptides with high content of tyrosine codon such as ND4, ND5, ND6 and COX2 in cells lines carrying homozygous YARS2 p.191Gly〉Val and m.11778G〉A mutations. The YARS2 p.191Gly〉Val mutation worsened the respiratory phenotypes associated with m.11778G〉A mutation, especially reducing activities of complexes I and IV. The respiratory deficiency altered the efficiency of mitochondrial ATP synthesis and increased the production of reactive oxygen species. Thus, mutated YARS2 aggravates mitochondrial dysfunctions associated with the m.11778G〉A mutation, exceeding the threshold for the expression of blindness phenotype. Our findings provided new insights into the pathophysiology of LHON that were manifested by interaction between mtDNA mutation and mutated nuclear-modifier YARS2 .

Description: The current status of ionospheric precursor studies associated with large earthquakes (EQ) is summarized in this report. It is a joint endeavor of the “Ionosphere Precursor Study Task Group,” which was formed ...

Description: Langmuir DOI: 10.1021/la200028x

Description: Messenger RNA (mRNA) secondary structure decreases the elongation rate, as ribosomes must unwind every structure they encounter during translation. Therefore, the strength of mRNA secondary structure is assumed to be reduced in highly translated mRNAs. However, previous studies in vitro reported a positive correlation between mRNA folding strength and protein abundance. The counterintuitive finding suggests that mRNA secondary structure affects translation efficiency in an undetermined manner. Here, we analyzed the folding behavior of mRNA during translation and its effect on translation efficiency. We simulated translation process based on a novel computational model, taking into account the interactions among ribosomes, codon usage and mRNA secondary structures. We showed that mRNA secondary structure shortens ribosomal distance through the dynamics of folding strength. Notably, when adjacent ribosomes are close, mRNA secondary structures between them disappear, and codon usage determines the elongation rate. More importantly, our results showed that the combined effect of mRNA secondary structure and codon usage in highly translated mRNAs causes a short ribosomal distance in structural regions, which in turn eliminates the structures during translation, leading to a high elongation rate. Together, these findings reveal how the dynamics of mRNA secondary structure coupling with codon usage affect translation efficiency.

Description: The use of multiple replication origins in archaea is not well understood. In particular, little is known about their specific control mechanisms. Here, we investigated the active replication origins in the three replicons of a halophilic archaeon, Haloarcula hispanica , by extensive gene deletion, DNA mutation and genome-wide marker frequency analyses. We revealed that individual origins are specifically dependent on their co-located cdc6 genes, and a single active origin/ cdc6 pairing is essential and sufficient for each replicon. Notably, we demonstrated that the activities of oriC1 and oriC2 , the two origins on the main chromosome, are differently controlled. A G-rich inverted repeat located in the internal region between the two inverted origin recognition boxes (ORBs) plays as an enhancer for oriC1 , whereas the replication initiation at oriC2 is negatively regulated by an ORB-rich region located downstream of oriC2-cdc6E , likely via Cdc6E-titrating. The oriC2 placed on a plasmid is incompatible with the wild-type (but not the oriC2 ) host strain, further indicating that strict control of the oriC2 activity is important for the cell. This is the first report revealing diverse control mechanisms of origins in haloarchaea, which has provided novel insights into the use and coordination of multiple replication origins in the domain of Archaea.

Description: Follistatin (FST) is essential for skeletal muscle development, but the intracellular signaling networks that regulate Follistatin-induced effects are not well defined. We sought to investigate whether FST promotes the proliferation of myoblasts through the phosphoinositide 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) signaling. In this study, we transfected the pEGFP-duFST plasmid and added PI3K and mTOR inhibitors to the medium of duck primary myoblasts. Then, we analyzed the cellular phenotypic changes that occurred and analyzed the expression of target genes. The results showed that FST promoted myoblast proliferation, induced the mRNA expression of PI3K, Akt, mTOR, 70-kDa ribosomal protein S6 kinase (S6K) and the protein expression of phospho-Akt (Thr308), mTOR, phospho-S6K (Ser417), inhibited the mRNA expression of FoxO1, muscle RING finger-1 (MuRF1) and the protein expression of phospho-FoxO1 (Ser256). Moreover, we found that the overexpression of FST could alleviate the inhibitory effect of myoblast proliferation caused by the addition of LY294002, a PI3K inhibitor. Additionally, the overexpression of duck FST also relieved the inhibition of myoblast proliferation caused by the addition of Rapamycin (an mTOR inhibitor) through PI3K/Akt/mTOR signaling. In light of the present results, we hypothesize that duck FST could promote myoblast proliferation, which is dependent on PI3K/Akt/mTOR signaling.

Description: Gene expression is modulated by multiple mechanisms, including genetic and/or epigenetic regulation, and associated with the processes of cellular differentiation and morphogenesis. Single nucleotide polymorphisms (SNPs) and DNA methylation play important roles in regulating gene expression. In this study, we focused on revealing the relationship between SNPs, DNA methylation and gene expression in two human populations genome-wide through proposing four regulation patterns and developed maximum likelihood estimate models. Using simulated data with different correlation coefficients between any two traits, the power of our approach showed a favourable performance and relative stability. In all, 6733 SNP–CpG-gene pairs including 957 genes were obtained in Northern European ancestry (CEU) population. As the results showed, SNPs and DNA methylation had approximately the same effect on expression regulation of 49% genes, which was termed cooperative/antagonistic regulation pattern. Less than 30% of genes are controlled only by one of the factors (SNP/DNA methylation). The others showed SNPs that affect methylation have no consequent effects or crosstalk regulation on gene expression. Similar result was shown in Yourba (YRI) population. Specific genes were inferred using the different mechanisms of gene regulation involved in complex diseases by combining literature. This approach provides a method to comprehensively assess regulation patterns of gene expression in the whole genome.

Description: 〈span〉〈div〉Abstract〈/div〉Interferometric virtual-source (VS) redatuming crosscorrelates downgoing waves with the corresponding upgoing waves to convert records from surface-source gathers to virtual gathers at the buried receiver locations. It can be viewed as the cancellation of common parts of the raypaths from surface sources to different buried receivers. As part of this process, a stacking operator — a uniform or simple offset function — is applied to weight and sum the surface-source array to form the VS. The stacking operator should preserve sources associated with effective cancellations of common raypaths and suppress ineffectively cancelling sources. The VS records should show reduced effects of overburden complexity, therefore providing improved image quality as well as improved repeatability in time-lapse monitoring. However, complex near-surface effects such as intricate shallow structures and variable weathering layers can severely distort the raypaths. As a result, sources associated with ineffective-raypath cancellation can produce substantial artifacts, instead of being spatially suppressed by the conventional stacking operator. To address these issues, we propose a data-driven VS method with a diversity-stacking theme in which each individual source contribution is weighted by certain quality measures. Specifically, we predict the upgoing wavefields using the conventional VS response and use the quality of these predictions compared with the original upgoing wavefields to approximate the weight of each source for the diversity stacking. Compared with previous methods, the new VS approach provides improved image quality and repeatability based on a pilot field of 13 time-lapse surveys, which reduced a significant repeatability problem across a 17-month survey gap.〈/span〉