BOL: Related items

COPE: an accurate k-mer-based pair-end reads connection tool to facilitate genome assembly

Jit — Wed, 06 Dec 2017 02:08:14 -0600

An efficient tool called Connecting Overlapped Pair-End (COPE) reads, to connect overlapping pair-end reads using k-mer frequencies. We evaluated our tool on 30× simulated pair-end reads from Arabidopsis thaliana with 1% base error. COPE connected over 99% of reads with 98.8% accuracy, which is, respectively, 10 and 2% higher than the recently published tool FLASH. When COPE is applied to real reads for genome assembly, the resulting contigs are found to have fewer errors and give a 14-fold improvement in the N50 measurement when compared with the contigs produced using unconnected reads.

Address of the bookmark: ftp://ftp.genomics.org.cn/pub/cope

Roslin Bioinformatics Group

Mon, 25 Nov 2013 23:55:25 -0600

Roslin Bioinformatics Group

The Law group provides internal Institute-specific development, training and support roles for data manipulation, sequence analysis and any other aspect of the analysis of biological data using computer systems. Additionally we provide databases and applications supporting the international animal science community, particularly tools and resources for genome mapping.

Head: Andy Law. Members: John Bowman (animal facility database applications), Zen Lu (bioinformatics support), Trevor Paterson (software development)

More @ http://www.bioinformatics.ed.ac.uk/groups/roslin-bioinformatics-group

String graph based genome assembly software and tools !

Rahul Nayak — Tue, 19 Dec 2017 17:17:38 -0600

In graph theory, a string graph is an intersection graph of curves in the plane; each curve is called a "string". String graphs were first proposed by E. W. Myers in a 2005 publication. In recent Genome Research paper describing an innovative approach for assembling large genomes from NGS data caught our attention for several reasons. i) it give different "string graph" prospective of long lasting genome assembly problem ii) the paper is coauthored by Jared Simpson, the developer of ABySS assembler and Richard Durbin. iii) Simpson-Durbin algorithm is that it does not rely on de Bruijn graphs, and instead employs a different graph construction approach called ‘string graph’.

Following are the genome assembly tools based on string graph:

1.SGA (String Graph Assembler) https://github.com/jts/sga

Assembles large genomes from high coverage short read data. SGA is designed as a modular set of programs, which are used to form an assembly pipeline. SGA implements a set of assembly algorithms based on the FM-index. As the FM-index is a compressed data structure, the algorithms are very memory efficient. The SGA assembly has three distinct phases. The first phase corrects base calling errors in the reads. The second phase assembles contigs from the corrected reads. The third phase uses paired end and/or mate pair data to build scaffolds from the contigs. The output of this software is a PDF report that allows the properties of the genome and data quality to be visually explored. By providing more information to the user at the start of an assembly project, this software will help increase awareness of the factors that make a given assembly easy or difficult, assist in the selection of software and parameters and help to troubleshoot an assembly if it runs into problems.

2. SAGE: String-overlap Assembly of GEnomes https://github.com/lucian-ilie/SAGE2

SAGE, for de novo genome assembly. As opposed to most assemblers, which are de Bruijn graph based, SAGE uses the string-overlap graph. SAGE builds upon great existing work on string-overlap graph and maximum likelihood assembly, bringing an important number of new ideas, such as the efficient computation of the transitive reduction of the string overlap graph, the use of (generalized) edge multiplicity statistics for more accurate estimation of read copy counts, and the improved use of mate pairs and min-cost flow for supporting edge merging. The assemblies produced by SAGE for several short and medium-size genomes compared favourably with those of existing leading assemblers.

3. FSG: Fast String Graph

The new integrated assembler has been assessed on a standard benchmark, showing that fast string graph (FSG) is significantly faster than SGA while maintaining a moderate use of main memory, and showing practical advantages in running FSG on multiple threads. Moreover, we have studied the effect of coverage rates on the running times.

4. BASE https://github.com/dhlbh/BASE

It enhances the classic seed-extension approach by indexing the reads efficiently to generate adaptive seeds that have high probability to appear uniquely in the genome. Such seeds form the basis for BASE to build extension trees and then to use reverse validation to remove the branches based on read coverage and paired-end information, resulting in high-quality consensus sequences of reads sharing the seeds. Such consensus sequences are then extended to contigs. BASE is a practically efficient tool for constructing contig, with significant improvement in quality for long NGS reads. It is relatively easy to extend BASE to include scaffolding.

5. Fermi https://github.com/lh3/fermi/

Fermi is a de novo assembler with a particular focus on assembling Illumina short sequence reads from a mammal-sized genome. In addition to the role of a typical assembler, fermi also aims to preserve heterozygotes which are often collapsed by other assemblers. Its ultimate goal is to find a minimal set of unitigs to represent all the information in raw reads.

If you want to learn about String Graph assembler, please read the following papers -

i) The Fragment Assembly String Graph - E. W. Myers

This paper describes the String Graph concept.

ii) Efficient construction of an assembly string graph using the FM-index - Jared T. Simpson and Richard Durbin

This earlier paper from Simpson and Durbin

iii) Efficient de novo assembly of large genomes using compressed data structures - Jared T. Simpson and Richard Durbin

PhD at University of Calgary

Fri, 27 Dec 2013 20:24:39 -0600

Institution/Company:
University of Calgary
Location:
Calgary, AB
Job Description:

Novel diagnostic platform for detection of Osteoarthritis

I invite applications from highly motivated individuals to join my laboratory as a PhD student in Systems Biology at the University of Calgary McCaig Institute for Bone and Joint Health. This project is aimed at characterizing the networks of physical (protein-protein) interactions underlying inflammatory processes in patients with Osteoarthritis and how this differs from patients with Rheumatoid Arthritis and normal individuals. This work will eventually lead to the development of a novel diagnostic platform for the non-invasive and accurate detection of early Osteoarthritis. The selected candidate will use state-of-the-art computational methodologies to systematically analyze proteomic data, and develop /implement new algorithms to identify protein and functional interaction networks from high throughput experimental data. The individual will also benefit by working closely with experts at the UofC and UofA through an AIHS Alberta Osteoarthritis Team Grant which includes experts from all pillars of health research. The candidate will also be supported to attend bioinformatics workshops and conferences to advance and disseminate their research.
Qualifications: The ideal candidate will have a Master’s degree in Computational Biology, Bioinformatics, or equivalent with strong background knowledge of the Biological Sciences, Biochemistry, and Microbiology. The individual should additionally have experience in handling high-throughput data sets as well as programming skills. The candidate will be registered as a PhD student in Dr. Krawetz’s laboratory, located in the new state-of-the-art Health Research Innovation Centre at the UofC. The individual will have strong verbal and written skills and the ability to work efficiently in a team environment.

In addition to the outstanding research opportunities available in this setting, students also enjoy the many cultural and sporting amenities provided in the city of Calgary, and can take advantage of the unparalleled skiing and hiking in the Rocky Mountains that are less than an hour away.

Candidates must be academically competitive and will be expected to apply for external funding. The stipend is $25,000/yr. For outstanding PhD students, internal top-up award opportunities are available on a competitive basis. If interested in joining the lab, please contact Dr. Krawetz directly at rkrawetz@ucalgary.ca and provide the following information:

- Short cover letter explaining your interest in the lab
- Resume
- Scanned copy of transcript or listing of course grades
- Names and contact information for two individuals who will be willing to provide letters of reference

MUMmer4: A fast and versatile genome alignment system

Jit — Sat, 03 Feb 2018 04:59:17 -0600

MUMmer4, a substantially improved version of MUMmer that addresses genome size constraints by changing the 32-bit suffix tree data structure at the core of MUMmer to a 48-bit suffix array, and that offers improved speed through parallel processing of input query sequences. With a theoretical limit on the input size of 141Tbp, MUMmer4 can now work with input sequences of any biologically realistic length. We show that as a result of these enhancements, the nucmer program in MUMmer4 is easily able to handle alignments of large genomes;

Address of the bookmark: https://mummer4.github.io/

Postdoc positions in computational biology - Center for Genomic Science - Milan, Italy

Thu, 12 Dec 2013 18:34:47 -0600

Job Description: three postdoc positions in computational biology are available at the Center for Genomic Science in Milan (Italy):

- Development of computational methods to investigate the interplay between epigenetic and genetic layers and their role in tumor progression, by integrating genomic, epigenomic and transcriptional data. PI: Mattia Pelizzola (http://tiny.cc/comEpi)
- Epigenome and transcriptome analysis in mouse models of Hepatocellular Carcinoma. PI: Bruno Amati - Small and long non-coding RNAs in cancer stem cells. PI: Francesco Nicassio

All projects will benefit from the availability of both in-house and publicly available next-generation sequencing datasets. Familiarity with Linux environment, programming skills (especially in R) and a background in either computational biology, or physics/engineering/math will be advantageous.

Deadline for the application January 6th, to apply: http://genomics.iit.it/resources.html

Start date: March 1st, 2014

Duration: 1+2 years

Contact Person (Referent): Mattia Pelizzola

Ref. E-Mail: mattia.pelizzola@iit.it

Tel: 0039-02-94375058
Group Web Page: http://genomics.iit.it

AlignGraph: algorithm for secondary de novo genome assembly guided by closely related references

Manisha Mishra — Tue, 17 Apr 2018 16:21:20 -0500

AlignGraph is a software that extends and joins contigs or scaffolds by reassembling them with help provided by a reference genome of a closely related organism.

Using AlignGraph

AlignGraph --read1 reads_1.fa --read2 reads_2.fa --contig contigs.fa --genome genome.fa --distanceLow distanceLow --distanceHigh distancehigh --extendedContig extendedContigs.fa --remainingContig remainingContigs.fa [--kMer k --insertVariation insertVariation --coverage coverage --part p --fastMap --ratioCheck --iterativeMap --misassemblyRemoval --resume]

Address of the bookmark: https://github.com/baoe/AlignGraph

EMBO practical Course on "Bioinformatics and Genomes Analyses" at Hellenic Pasteur Institute, Athens, Greece

Sat, 21 Dec 2013 10:00:24 -0600

The main objectives of this Practical Course are to strengthen skills
of PhD students and young researchers in the domain of Bioinformatics
and Genome Data Analyses on the use of advanced fundamental algorithms
and their applications in genome studies.

The course topics will include theoretical and practical aspects in:
- Genomes comparisons,
- Evolutionary analyses (orthologs, paralogs and ancestral genomes
inference),
- RNAseq and Next Generation Sequencing (including algorithms, methods
and sequence mapping tools, data analyses and applications).

The course programme will be centred on theoretical presentations
followed by practical sessions. Practical sessions in a Linux
environment will involve Unix shell and Perl scripting. Participants
are assumed to be familiar with this environment.

A series of lectures delivered by prominent scientists on recent hot
topics in genome (Viruses, Prokaryotes, Eukaryotes) studies will be
included in the programme and future research perspectives will be
highlighted.

The topics that will be included in the course programme are similar
to those included in previously organized courses:http://www.pasteur.fr/~tekaia/BGA_courses.html

The course is aimed at motivated Ph.D students and Post-Doctoral
Researchers in Academic Institutions, with background in Mathematics,
Statistics, Biology or Computer Science and who are involved in
Bioinformatics and Genomes studies.

Selection of participants will be based on their background, running
research projects and on expressed motivations.
Selected students will have free accommodation and meals and are
expected to contribute with 200 euros and to pay for their travel
expenses.
All participants (students and invited speakers) will stay in the same
hotel.

Detailed indications are available on the course web site: http://events.embo.org/14-comparative-genomics/index.html

Candidates are advised to complete carefully the application form,
together with an abstract of at least one of their running projects, a
"one-page CV" and a personal Identity Picture (Photo).

The application deadline is March 14, 2014.

The organizers:
Menelaos Manoussakis, Hellenic Pasteur Institute, Athens, Greece.
Evdokia Karagouni, Hellenic Pasteur Institute, Athens - Greece.
Evie Melanitou, Institut Pasteur Paris - France.
Fredj Tekaia ( Institut Pasteur Paris France)
URL: http://www.pasteur.fr/~tekaia/BGA_courses.html

Date: 5 – 17 May, 2014.
More at http://events.embo.org/14-comparative-genomics/index.html
will take place in the ,

CrossMap: a program for convenient conversion of genome coordinates

Jit — Thu, 31 May 2018 06:00:47 -0500

CrossMap is a program for convenient conversion of genome coordinates (or annotation files) between different assemblies (such as Human hg18 (NCBI36) <> hg19 (GRCh37), Mouse mm9 (MGSCv37) <> mm10 (GRCm38)). It supports most commonly used file formats including SAM/BAM, Wiggle/BigWig, BED, GFF/GTF, VCF. CrossMap is designed to liftover genome coordinates between assemblies. It’s not a program for aligning sequences to reference genome. We do not recommend using CrossMap to convert genome coordinates between species.

Address of the bookmark: http://crossmap.sourceforge.net

Oldest Hominin DNA Sequenced

Surajeet — Fri, 27 Dec 2013 19:58:31 -0600

Matthias Meyer and his team from the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, have developed new techniques for retrieving and sequencing highly degraded ancient DNA. They then joined forces with Juan-Luis Arsuaga and applied the new techniques to a cave bear from the Sima de los Huesos site. After this success, the researchers sampled two grams of bone powder from a hominin thigh bone from the cave. They extracted its DNA and sequenced the genome of the mitochondria or mtDNA, a small part of the genome that is passed down along the maternal line and occurs in many copies per cell. The researchers then compared this ancient mitochondrial DNA with Neandertals, Denisovans, present-day humans, and apes.

From the missing mutations in the old DNA sequences the researchers calculated that the Sima hominin lived about 400,000 years ago. They also found that it shared a common ancestor with the Denisovans, an extinct archaic group from Asia related to the Neandertals, about 700,000 years ago. "The fact that the mtDNA of the Sima de los Huesos hominin shares a common ancestor with Denisovan rather than Neandertal mtDNAs is unexpected since its skeletal remains carry Neandertal-derived features," says Matthias Meyer. Considering their age and Neandertal-like features, the Sima hominins were likely related to the population ancestral to both Neandertals and Denisovans. Another possibility is that gene flow from yet another group of hominins brought the Denisova-like mtDNA into the Sima hominins or their ancestors.

Reference

http://www.sciencedaily.com/releases/2013/12/131204132018.htm