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  • 1
    Publication Date: 2016-08-05
    Description: De novo genes, which originate from ancestral nongenic sequences, are one of the most important sources of protein-coding genes. This origination process is crucial for the adaptation of organisms. However, how de novo genes arise and become fixed in a population or species remains largely unknown. Here, we identified 782 de novo genes from the model plant Arabidopsis thaliana and divided them into three types based on the availability of translational evidence, transcriptional evidence, and neither transcriptional nor translational evidence for their origin. Importantly, by integrating multiple types of omics data, including data from genomes, epigenomes, transcriptomes, and translatomes, we found that epigenetic modifications (DNA methylation and histone modification) play an important role in the origination process of de novo genes. Intriguingly, using the transcriptomes and methylomes from the same population of 84 accessions, we found that de novo genes that are transcribed in approximately half of the total accessions within the population are highly methylated, with lower levels of transcription than those transcribed at other frequencies within the population. We hypothesized that, during the origin of de novo gene alleles, those neutralized to low expression states via DNA methylation have relatively high probabilities of spreading and becoming fixed in a population. Our results highlight the process underlying the origin of de novo genes at the population level, as well as the importance of DNA methylation in this process.
    Electronic ISSN: 1759-6653
    Topics: Biology
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  • 2
    Publication Date: 2013-10-01
    Description: Thanks to the microarray technology, our understanding of transcriptome evolution at the genome level has been considerably advanced in the past decade. Yet, further investigation was challenged by several technical limitations of this technology. Recent innovation of next-generation sequencing, particularly the invention of RNA-seq technology, has shed insightful lights on resolving this problem. Though a number of statistical and computational methods have been developed to analyze RNA-seq data, the analytical framework specifically designed for evolutionary genomics remains an open question. In this article we develop a new method for estimating the genome expression distance from the RNA-seq data, which has explicit interpretations under the model of gene expression evolution. Moreover, this distance measure takes the data overdispersion, gene length variation, and sequencing depth variation into account so that it can be applied to multiple genomes from different species. Using mammalian RNA-seq data as example, we demonstrated that this expression distance is useful in phylogenomic analysis.
    Electronic ISSN: 1759-6653
    Topics: Biology
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  • 3
    Publication Date: 2013-09-18
    Description: This paper investigates the forced second-order consensus problem in directed networks with time delays. First, a general forced consensus protocol is studied and some sufficient and necessary conditions on control parameters are obtained to guarantee the forced consensus; based on these conditions, several convenient methods for choosing parameters are provided. Then, by analysing the poles of the closed-loop system, the delay sensitivity of the protocol is investigated. The maximal upper bound of the allowable delays is provided. Simulation examples are presented to illustrate the effectiveness of the theoretical results.
    Print ISSN: 0265-0754
    Electronic ISSN: 1471-6887
    Topics: Mathematics
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  • 4
    Publication Date: 2015-10-18
    Description: Both gamma-ray bursts (GRBs) and blazars have relativistic jets pointing at a small angle from our line of sight. Several recent studies suggested that these two kinds of sources may share similar jet physics. In this work, we explore the variability properties for GRBs and blazars as a whole. We find that the correlation between minimum variability time-scale (MTS) and Lorentz factor, , as found only in GRBs by Sonbas et al. can be extended to blazars with a joint correlation of MTS –4.7±0.3 . The same applies to the $\rm MTS\propto \it L_{\gamma }^{\rm -1.0\pm 0.1}$ correlation as found in GRBs, which can be well extended into blazars as well. These results provide further evidence that the jets in these two kinds of sources are similar despite of the very different mass scale of their central engines. Further investigations of the physical origin of these correlations are needed, which can shed light on the nature of the jet physics.
    Print ISSN: 1745-3925
    Electronic ISSN: 1745-3933
    Topics: Physics
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  • 5
    Publication Date: 2016-08-11
    Description: Motivation: Timely surveillance of the antigenic dynamics of the influenza virus is critical for accurate selection of vaccine strains, which is important for effective prevention of viral spread and infection. Results: Here, we provide a computational platform, called PREDAC-H3, for antigenic surveillance of human influenza A(H3N2) virus based on the sequence of surface protein hemagglutinin (HA). PREDAC-H3 not only determines the antigenic variants and antigenic cluster (grouped for similar antigenicity) to which the virus belongs, based on HA sequences, but also allows visualization of the spatial distribution and temporal dynamics of antigenic clusters of viruses isolated from around the world, thus assisting in antigenic surveillance of human influenza A(H3N2) virus. Availability and Implementation: It is publicly available from: http://biocloud.hnu.edu.cn/influ411/html/index.php . Contacts : yshu@cnic.org.cn or taijiao@moon.ibp.ac.cn
    Print ISSN: 1367-4803
    Electronic ISSN: 1460-2059
    Topics: Biology , Computer Science , Medicine
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  • 6
    Publication Date: 2016-08-28
    Description: Chlamydial species are common intracellular parasites that cause various diseases, mainly characterized by persistent infection, which lead to inflammatory responses modulated by pattern recognition receptors (PRRs). The best understood PRRs are the extracellular Toll-like receptors, but recent significant advances have focused on two important proteins, NOD1 and NOD2, which are members of the intracellular nucleotide-binding oligomerization domain receptor family and are capable of triggering the host innate immune signaling pathways. This results in the production of pro-inflammatory cytokines, which is vital for an adequate host defense against intracellular chlamydial infection. NOD1/2 ligands are known to derive from peptidoglycan, and the latest research has resolved the paradox of whether chlamydial species possess this bacterial cell wall component; this finding is likely to promote in-depth investigations into the interaction between the NOD proteins and chlamydial pathogens. In this review, we summarize the basic characteristics and signal transduction functions of NOD1 and NOD2 and highlight the new research on the roles of NOD1 and NOD2 in the host defense against chlamydial infection.
    Keywords: Pathogens & Pathogenicity
    Print ISSN: 0378-1097
    Electronic ISSN: 1574-6968
    Topics: Biology
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  • 7
    Publication Date: 2012-10-13
    Description: In this paper, we study the existence, uniqueness and regularity properties of solutions for the nonstandard Volterra integral equation . We then present a collocation method to solve this equation, and analyse the convergence and superconvergence of piecewise polynomial collocation approximations. We also illustrate the theoretical results by extensive numerical experiments.
    Print ISSN: 0272-4979
    Electronic ISSN: 1464-3642
    Topics: Mathematics
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  • 8
    Publication Date: 2012-05-13
    Description: Nucleotide excision repair (NER) is a major repair pathway that recognizes and corrects various lesions in cellular DNA. We hypothesize that damage recognition is an initial step in NER that senses conformational anomalies in the DNA caused by lesions. We prepared three DNA duplexes containing the carcinogen adduct N -(2'-deoxyguanosin-8-yl)-7-fluoro-2-acetylaminofluorene (FAAF) at G 1 , G 2 or G 3 of Nar I sequence (5'-CCG 1 G 2 CG 3 CC-3'). Our 19 F-NMR/ICD results showed that FAAF at G 1 and G 3 prefer syn S- and W-conformers, whereas anti B-conformer was predominant for G 2 . We found that the repair of FAAF occurs in a conformation-specific manner, i.e. the highly S/W-conformeric G 3 and -G 1 duplexes incised more efficiently than the B-type G 2 duplex (G 3 ~G 1 〉 G 2 ). The melting and thermodynamic data indicate that the S- and W-conformers produce greater DNA distortion and thermodynamic destabilization. The N -deacetylated N -(2'-deoxyguanosin-8-yl)-7-fluoro-2-aminofluorene (FAF) adducts in the same Nar I sequence are repaired 2- to 3-fold less than FAAF: however, the incision efficiency was in order of G 2 ~G 1 〉 G 3 , a reverse trend of the FAAF case. We have envisioned the so-called N -acetyl factor as it could raise conformational barriers of FAAF versus FAF. The present results provide valuable conformational insight into the sequence-dependent UvrABC incisions of the bulky aminofluorene DNA adducts.
    Print ISSN: 0305-1048
    Electronic ISSN: 1362-4962
    Topics: Biology
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  • 9
    Publication Date: 2014-04-05
    Description: Collagen VI-related myopathies are disorders of connective tissue presenting with an overlap phenotype combining clinical involvement from the muscle and from the connective tissue. Not all patients displaying related overlap phenotypes between muscle and connective tissue have mutations in collagen VI. Here, we report a homozygous recessive loss of function mutation and a de novo dominant mutation in collagen XII (COL12A1) as underlying a novel overlap syndrome involving muscle and connective tissue. Two siblings homozygous for a loss of function mutation showed widespread joint hyperlaxity combined with weakness precluding independent ambulation, while the patient with the de novo missense mutation was more mildly affected, showing improvement including the acquisition of walking. A mouse model with inactivation of the Col12a1 gene showed decreased grip strength, a delay in fiber-type transition and a deficiency in passive force generation while the muscle seems more resistant to eccentric contraction induced force drop, indicating a role for a matrix-based passive force-transducing elastic element in the generation of the weakness. This new muscle connective tissue overlap syndrome expands on the emerging importance of the muscle extracellular matrix in the pathogenesis of muscle disease.
    Print ISSN: 0964-6906
    Electronic ISSN: 1460-2083
    Topics: Biology , Medicine
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  • 10
    Publication Date: 2014-04-05
    Description: Bethlem myopathy (BM) [MIM 158810] is a slowly progressive muscle disease characterized by contractures and proximal weakness, which can be caused by mutations in one of the collagen VI genes ( COL6A1 , COL6A2 and COL6A3 ) . However, there may be additional causal genes to identify as in ~50% of BM cases no mutations in the COL6 genes are identified. In a cohort of –24 patients with a BM-like phenotype, we first sequenced 12 candidate genes based on their function, including genes for known binding partners of collagen VI, and those enzymes involved in its correct post-translational modification, assembly and secretion. Proceeding to whole-exome sequencing (WES), we identified mutations in the COL12A1 gene, a member of the FACIT collagens (fibril-associated collagens with interrupted triple helices) in five individuals from two families. Both families showed dominant inheritance with a clinical phenotype resembling classical BM. Family 1 had a single-base substitution that led to the replacement of one glycine residue in the triple-helical domain, breaking the Gly-X-Y repeating pattern, and Family 2 had a missense mutation, which created a mutant protein with an unpaired cysteine residue. Abnormality at the protein level was confirmed in both families by the intracellular retention of collagen XII in patient dermal fibroblasts. The mutation in Family 2 leads to the up-regulation of genes associated with the unfolded protein response (UPR) pathway and swollen, dysmorphic rough-ER. We conclude that the spectrum of causative genes in extracellular matrix (ECM)-related myopathies be extended to include COL12A1 .
    Print ISSN: 0964-6906
    Electronic ISSN: 1460-2083
    Topics: Biology , Medicine
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