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Kevin A Yamauchi, Augusto M Tentori, Amy E Herr
Isoelectric focusing (IEF) is a powerful separation method, useful for resolving subtle changes in the isoelectric point of unlabeled proteins. While microfluidic IEF has reduced the separation times from the hours in traditional benchtop IEF to minutes, the enclosed devices hinder post-separation access to the sample for downstream analysis. The two-layer open IEF device presented here comprises a photopatterned hydrogel lid layer containing the chemistries required for IEF and a thin polyacrylamide bottom layer in which the analytes are separated...
January 31, 2018: Electrophoresis
Hannan Ai, Yuncan Ai, Fanmei Meng
Assessing correctness of an assembled chromosome architecture is a central challenge. We create a geometric analysis method (called GenomeLandscaper) to conduct landscape analysis of genome-fingerprints maps (GFM), trace large-scale repetitive regions, and assess their impacts on the global architectures of assembled chromosomes. We develop an alignment-free method for phylogenetics analysis. The human Y chromosomes (GRCh.chrY, HuRef.chrY and YH.chrY) are analysed as a proof-of-concept study. We construct a galaxy of genome-fingerprints maps (GGFM) for them, and a landscape compatibility among relatives is observed...
January 18, 2018: Scientific Reports
Raúl Martin Amado Cattáneo, Luis Diambra, Andrés Norman McCarthy
Phylogenetics and population genetics are central disciplines in evolutionary biology. Both are based on the comparison of single DNA sequences, or a concatenation of a number of these. However, with the advent of next-generation DNA sequencing technologies, the approaches that consider large genomic data sets are of growing importance for the elucidation of evolutionary relationships among species. Among these approaches, the assembly and alignment-free methods which allow an efficient distance computation and phylogeny reconstruction are of great importance...
January 16, 2018: Mitochondrial DNA. Part A. DNA Mapping, Sequencing, and Analysis
Xin Zhao, Kun Tian, Rong L He, Stephen S-T Yau
Prochlorococcus marinus, one of the most abundant marine cyanobacteria in the global ocean, is classified into low-light (LL) and high-light (HL) adapted ecotypes. These two adapted ecotypes differ in their ecophysiological characteristics, especially whether adapted for growth at high-light or low-light intensities. However, some evolutionary relationships of Prochlorococcus phylogeny remain to be resolved, such as whether the strains SS120 and MIT9211 form a monophyletic group. We use the Natural Vector (NV) method to represent the sequence in order to identify the phylogeny of the Prochlorococcus...
December 2017: Ecology and Evolution
James Lara, Mahder Teka, Yury Khudyakov
BACKGROUND: Identification of acute or recent hepatitis C virus (HCV) infections is important for detecting outbreaks and devising timely public health interventions for interruption of transmission. Epidemiological investigations and chemistry-based laboratory tests are 2 main approaches that are available for identification of acute HCV infection. However, owing to complexity, both approaches are not efficient. Here, we describe a new sequence alignment-free method to discriminate between recent (R) and chronic (C) HCV infection using next-generation sequencing (NGS) data derived from the HCV hypervariable region 1 (HVR1)...
December 6, 2017: BMC Genomics
Burkhard Morgenstern, Svenja Schöbel, Chris-André Leimeister
Background: Various approaches to alignment-free sequence comparison are based on the length of exact or inexact word matches between pairs of input sequences. Haubold et al. (J Comput Biol 16:1487-1500, 2009) showed how the average number of substitutions per position between two DNA sequences can be estimated based on the average length of exact common substrings. Results: In this paper, we study the length distribution of k-mismatch common substrings between two sequences...
2017: Algorithms for Molecular Biology: AMB
Yuxin Qiao, Xiaoyan Zhao, Jun Zhu, Ran Tu, Libing Dong, Li Wang, Zhiyang Dong, Qinhong Wang, Wenbin Du
Lipases are ubiquitous enzymes of great physiological significance that have been used extensively in multiple industries. Environmental microorganisms are a major source for the discovery of novel lipases with high catalytic efficiency and selectivity. However, current plate-based screening of lipase-producing strains is time consuming, labour intensive and inefficient. In this study, we developed an ultra-high throughput screening pipeline for lipase-producing strains based on fluorescence-activated droplet sorting (FADS) using a compact optical system that could be easily set up in an alignment-free manner...
December 11, 2017: Lab on a Chip
Brian B Luczak, Benjamin T James, Hani Z Girgis
Motivation: Since the dawn of the bioinformatics field, sequence alignment scores have been the main method for comparing sequences. However, alignment algorithms are quadratic, requiring long execution time. As alternatives, scientists have developed tens of alignment-free statistics for measuring the similarity between two sequences. Results: We surveyed tens of alignment-free k-mer statistics. Additionally, we evaluated 33 statistics and multiplicative combinations between the statistics and/or their squares...
December 6, 2017: Briefings in Bioinformatics
Yuki Kato, Jan Gorodkin, Jakob Hull Havgaard
BACKGROUND: Structured non-coding RNAs play many different roles in the cells, but the annotation of these RNAs is lacking even within the human genome. The currently available computational tools are either too computationally heavy for use in full genomic screens or rely on pre-aligned sequences. METHODS: Here we present a fast and efficient method, DotcodeR, for detecting structurally similar RNAs in genomic sequences by comparing their corresponding coarse-grained secondary structure dot plots at string level...
December 2, 2017: BMC Genomics
Jan Dreher, Josef Scheiber, Nikolaus Stiefl, Knut Baumann
A novel alignment-free molecular descriptor called xMaP (flexible MaP descriptor) is introduced. The descriptor is the advancement of the previously published translationally and rotationally invariant 3D descriptor MaP (Mapping Property distributions onto the molecular surface) to the 4th dimension. In addition to MaP, xMaP is independent of the chosen starting conformation of the encoded molecules and is therefore entirely alignment-free. This is achieved by using ensembles of conformers, which are generated by conformational searches...
November 27, 2017: Journal of Chemical Information and Modeling
Marco Beccuti, Elisa Genuardi, Greta Romano, Luigia Monitillo, Daniela Barbero, Mario Boccadoro, Marco Ladetto, Raffaele Calogero, Simone Ferrero, Francesca Cordero
BACKGROUND: Mantle Cell Lymphoma (MCL) is a B cell aggressive neoplasia accounting for about the 6% of all lymphomas. The most common molecular marker of clonality in MCL, as in other B lymphoproliferative disorders, is the ImmunoGlobulin Heavy chain (IGH) rearrangement, occurring in B-lymphocytes. The patient-specific IGH rearrangement is extensively used to monitor the Minimal Residual Disease (MRD) after treatment through the standardized Allele-Specific Oligonucleotides Quantitative Polymerase Chain Reaction based technique...
November 23, 2017: BMC Bioinformatics
Jagadesan Sankarasubramanian, Udayakumar S Vishnu, Paramasamy Gunasekaran, Jeyaprakash Rajendhran
Brucellosis is an important zoonotic disease caused by Brucella spp. We present a phylogeny of 552 strains based on genome-wide single nucleotide polymorphisms (SNPs) determined by an alignment-free k-mer approach. A total of 138,029 SNPs were identified from 552 Brucella genomes. Of these, 31,152 and 106,877 were core and non-core SNPs, respectively. Based on pan-genome analysis 11,937 and 972 genes were identified as pan and core genome, respectively. The pan-genome-wide analysis studies (Pan-GWAS) could not identify the group-specific variants in Brucella spp...
November 15, 2017: Infection, Genetics and Evolution
Yifei Zhang, Alexander V Alekseyenko
The diversity of microbiota is best explored by understanding the phylogenetic structure of the microbial communities. Traditionally, sequence alignment has been used for phylogenetic inference. However, alignment-based approaches come with significant challenges and limitations when massive amounts of data are analyzed. In the recent decade, alignment-free approaches have enabled genome-scale phylogenetic inference. Here we evaluate three alignment-free methods: ACS, CVTree, and Kr for phylogenetic inference with 16s rRNA gene data...
2017: PloS One
Jianyu Zhou, Shining Ma, Dongfang Wang, Jianyang Zeng, Tao Jiang
Alternative splicing plays an important role in many cellular processes of eukaryotic organisms. The exon-inclusion ratio, also known as percent spliced in, is often regarded as one of the most effective measures of alternative splicing events. The existing methods for estimating exon-inclusion ratios at the genome scale all require the existence of a reference transcriptome. In this paper, we propose an alignment-free method, FreePSI, to perform genome-wide estimation of exon-inclusion ratios from RNA-Seq data without relying on the guidance of a reference transcriptome...
November 9, 2017: Nucleic Acids Research
Fazle E Faisal, Khalique Newaz, Julie L Chaney, Jun Li, Scott J Emrich, Patricia L Clark, Tijana Milenković
Initial protein structural comparisons were sequence-based. Since amino acids that are distant in the sequence can be close in the 3-dimensional (3D) structure, 3D contact approaches can complement sequence approaches. Traditional 3D contact approaches study 3D structures directly and are alignment-based. Instead, 3D structures can be modeled as protein structure networks (PSNs). Then, network approaches can compare proteins by comparing their PSNs. These can be alignment-based or alignment-free. We focus on the latter...
November 2, 2017: Scientific Reports
Hyein Seo, Dong-Ho Cho
The sequence comparison is an important part in bioinformatics to understand the biological property of genome. Although the alignment based sequence comparison is traditional and reliable algorithm, alignment free methods have been actively researched because of their advantage in terms of computational complexity. In this paper, we suggest a new alignment free genome comparison scheme based on statistical approach. From sequence components, word frequency information of the sequence is estimated. By investigating the relationship between estimated frequency information and actual word frequency, the characteristics of the sequence are numerically represented...
July 2017: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
Yong-Joon Song, Dong-Ho Cho
In order to extract phylogenetic information from DNA sequences, alignment-free methods and alignment-based methods are used. Alignment-based methods have high complexity and conventional alignment-free methods have low accuracy. In this paper, a new alignment-free method based on the distribution of repeated k-word measure is proposed. This novel measure is based on k-words and its multiple repeated words. We can get higher performance than conventional word count methods in case of using proposed scheme while maintaining total time complexity...
July 2017: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
Gyu-Bum Han, Byung Chang Chung, Dong-Ho Cho
This paper proposes a novel alignment-free sequence comparison method to identify the genetic relationships of organisms with a high resolution. For an accurate comparison, both frequency and position information of k-words are obtained from genome sequences in the proposed alignment-free sequence comparison method. Using principal component analysis (PCA) and phylogeny analysis, we identify the classification performance of proposed method. Then, the phylogenetic trees of proposed and conventional schemes are compared with reliable reference tree...
July 2017: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
Nikolaj Kofoed Mandsberg, Ole Hansen, Rafael Taboryski
Droplet array chips were realized using an alignment-free fabrication process in silicon. The chips were textured with a homogeneous nano-scale surface roughness but were partially covered with a self-assembled monolayer of perfluorodecyltrichlorosilane (FDTS), resulting in a super-biphilic surface. When submerged in water and withdrawn again, microliter sized droplets are formed due to pinning of water on the hydrophilic spots. The entrained droplet volumes were investigated under variation of spot size and withdrawal velocity...
October 6, 2017: Scientific Reports
Xin Bai, Kujin Tang, Jie Ren, Michael Waterman, Fengzhu Sun
BACKGROUND: Alignment-free sequence comparison using counts of word patterns (grams, k-tuples) has become an active research topic due to the large amount of sequence data from the new sequencing technologies. Genome sequences are frequently modelled by Markov chains and the likelihood ratio test or the corresponding approximate χ (2)-statistic has been suggested to compare two sequences. However, it is not known how to best choose the word length k in such studies. RESULTS: We develop an optimal strategy to choose k by maximizing the statistical power of detecting differences between two sequences...
October 3, 2017: BMC Genomics
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