DNA Methylation Variation Is Identified in Monozygotic Twins Discordant for Congenital Heart Diseases

Aims:Multiple genes and environmental factors are known to be involved in congenital heart disease(CHD),but epigenetic variation has received little attention.Monozygotic(MZ)twins with CHD provide a unique model for exploring this phenomenon.In order to investigate the potential role of Deoxyribonucleic Acid(DNA)methyla-tion in CHD pathogenesis,the present study examined DNA methylation variation in MZ twins discordant for CHD,especially ventricular septal defect(VSD).Methods and Results:Using genome-wide DNA methylation profiles,we identified 4004 differentially methylated regions(DMRs)in 18 MZ twin pairs discordant for CHD,and 2826 genes were identified.Gene Ontology(GO)and Kyoto Encyclopedia of Genes and Genomes(KEGG)analysis revealed a list of CHD-associated pathways.To further investigate the role of DNA methylation in VSD,data from 7 pairs of MZ twins with VSD were analyzed.We identified 1614 DMRs corresponding to 1443 genes associated with arrhythmogenic right ventricular cardiomyopathy,cyclic guanosine monopho-sphate-protein kinase G(cGMP-PKG)signaling pathway by KEGG analysis,and cell-cell adhesion,calcium ion transmembrane transport by GO analysis.A proportion of DMR-associated genes were involved in calcium signaling pathways.The methylation changes of calcium signaling genes might be related to VSD pathogenesis.Conclusion:CHD is associated with differential DNA methylation in MZ twins.CHD may be etiologically linked to DNA methylation,and methylation of calcium signaling genes may be involved in the development of VSD.

Global Convergence of a Modified Tri-Dimensional Filter Method

In this paper, a tri-dimensional filter method for nonlinear programming was proposed. We add a parameter into the traditional filter for relaxing the criterion of iterates. The global convergent properties of the proposed algorithm are proved under some appropriate conditions.

Rhizosheath formation and involvement in foxtail millet(Setaria italica) root growth under drought stress

The rhizosheath, a layer of soil particles that adheres firmly to the root surface by a combination of root hairs and mucilage, may improve tolerance to drought stress. Setaria italica(L.) P. Beauv.(foxtail millet), a member of the Poaceae family, is an important food and fodder crop in arid regions and forms a larger rhizosheath under drought conditions. Rhizosheath formation under drought conditions has been studied, but the regulation of root hair growth and rhizosheath size in response to soil moisture remains unclear. To address this question, in this study we monitored root hair growth and rhizosheath development in response to a gradual decline in soil moisture. Here, we determined that a soil moisture level of 10%–14%(w/w)stimulated greater rhizosheath production compared to other soil moisture levels. Root hair density and length also increased at this soil moisture level, which was validated by measurement of the expression of root hair-related genes.These findings contribute to our understanding of rhizosheath formation in response to soil water stress.

Multiplexed site-specific genome engineering in Mycolicibacterium neoaurum by Att/Int system

Genomic integration of genes and pathway-sized DNA cassettes is often an indispensable way to construct robust and productive microbial cell factories.For some uncommon microbial hosts,such as Mycolicibacterium and Mycobacterium species,however,it is a challenge.Here,we present a multiplexed integrase-assisted site-specific recombination(miSSR)method to precisely and iteratively integrate genes/pathways with controllable copies in the chromosomes of Mycolicibacteria for the purpose of developing cell factories.First,a single-step multi-copy integration method was established in M.neoaurum by a combination application of mycobacteriophage L5 integrase and two-step allelic exchange strategy,the efficiencies of which were~100%for no more than three-copy integration events and decreased sharply to~20%for five-copy integration events.Second,the R4,Bxb1 andΦC31 bacteriophage Att/Int systems were selected to extend the available integration toolbox for multiplexed gene integration events.Third,a reconstructed mycolicibacterial Xer recombinases(Xer-cise)system was employed to recycle the selection marker of gene recombination to facilitate the iterative gene manipulation.As a proof of concept,the biosynthetic pathway of ergothioneine(EGT)in Mycolicibacterium neoaurum ATCC 25795 was achieved by remodeling its metabolic pathway with a miSSR system.With six copies of the biosynthetic gene clusters(BGCs)of EGT and pentose phosphate isomerase(PRT),the titer of EGT in the resulting strain in a 30 mL shake flask within 5 days was enhanced to 66 mg/L,which was 3.77 times of that in the wild strain.The improvements indicated that the miSSR system was an effective,flexible,and convenient tool to engineer the genomes of Mycolicibacteria as well as other strains in the Mycobacteriaceae due to their proximate evolutionary relationships.