scholarly journals Early vertebrate origin of CTCFL, a CTCF paralog, revealed by proximity-guided shark genome scaffolding

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Mitsutaka Kadota ◽  
Kazuaki Yamaguchi ◽  
Yuichiro Hara ◽  
Shigehiro Kuraku
Keyword(s):  
PLoS ONE ◽  
2013 ◽  
Vol 8 (6) ◽  
pp. e66922 ◽  
Author(s):  
Michael D. Barton ◽  
Hazel A. Barton
Keyword(s):  

2015 ◽  
Author(s):  
Kristoffer Sahlin ◽  
Rayan Chikhi ◽  
Lars Arvestad

Scaffolding is often an essential step in a genome assembly process,in which contigs are ordered and oriented using read pairs from a combination of paired-ends libraries and longer-range mate-pair libraries. Although a simple idea, scaffolding is unfortunately hard to get right in practice. One source of problem is so-called PE-contamination in mate-pair libraries, in which a non-negligible fraction of the read pairs get the wrong orientation and a much smaller insert size than what is expected. This contamination has been discussed in previous work on integrated scaffolders in end-to-end assemblers such as Allpaths-LG and MaSuRCA but the methods relies on the fact that the orientation is observable, \emph{e.g.}, by finding the junction adapter sequence in the reads. This is not always the case, making orientation and insert size of a read pair stochastic. Furthermore, work on modeling PE-contamination has so far been disregarded in stand-alone scaffolders and the effect that PE-contamination has on scaffolding quality has not been examined before. We have addressed PE-contamination in an update of our scaffolder BESST. We formulate the problem as an Integer Linear Program (ILP) and use characteristics of the problem, such as contig lengths and insert size, to efficiently solve the ILP using a linear amount (with respect to the number of contigs) of Linear Programs. Our results show significant improvement over both integrated and standalone scaffolders. The impact of modeling PE-contamination is quantified by comparison with the previous BESST model. We also show how other scaffolders are vulnerable to PE-contaminated libraries, resulting in increased number of misassemblies, more conservative scaffolding, and inflated assembly sizes. The model is implemented in BESST. Source code and usage instructions are found at https://github.com/ksahlin/BESST. BESST can also be downloaded using PyPI.


2020 ◽  
Vol 27 (4) ◽  
pp. 519-533 ◽  
Author(s):  
Weihua Pan ◽  
Tao Jiang ◽  
Stefano Lonardi

2019 ◽  
Author(s):  
Weihua Pan ◽  
Tao Jiang ◽  
Stefano Lonardi

AbstractDue to the current limitations of sequencing technologies,de novogenome assembly is typically carried out in two stages, namely contig (sequence) assembly and scaffolding. While scaffolding is computationally easier than sequence assembly, the scaffolding problem can be challenging due to the high repetitive content of eukaryotic genomes, possible mis-joins in assembled contigs and inaccuracies in the linkage information. Genome scaffolding tools either use paired-end/mate-pair/linked/Hi-C reads or genome-wide maps (optical, physical or genetic) as linkage information. Optical maps (in particular Bionano Genomics maps) have been extensively used in many recent large-scale genome assembly projects (e.g., goat, apple, barley, maize, quinoa, sea bass, among others). However, the most commonly used scaffolding tools have a serious limitation: they can only deal with one optical map at a time, forcing users to alternate or iterate over multiple maps. In this paper, we introduce a novel scaffolding algorithm called OMGS that for the first time can take advantages of multiple optical maps. OMGS solves several optimization problems to generate scaffolds with optimal contiguity and correctness. Extensive experimental results demonstrate that our tool outperforms existing methods when multiple optical maps are available, and produces comparable scaffolds using a single optical map. OMGS can be obtained fromhttps://github.com/ucrbioinfo/OMGS


2017 ◽  
Author(s):  
Sebastien François ◽  
Rumen Andonov ◽  
Dominique Lavenier ◽  
Hristo Djidjev

AbstractWe describe a global optimization approach for genome assembly where the steps of scaffolding, gap-filling, and scaffold extension are simultaneously solved in the framework of a common objective function. The approach is based on integer programming model for solving genome scaffolding as a problem of finding a long simple path in a specific graph that satisfies additional constraints encoding the insert-size information. The optimal solution of this problem allows one to obtain new kind of contigs that we call distance-based contig. We test the algorithm on a benchmark of chloroplasts and compare the quality of the results with recent scaffolders.


2014 ◽  
Vol 15 (S9) ◽  
Author(s):  
James Lindsay ◽  
Hamed Salooti ◽  
Ion Măndoiu ◽  
Alex Zelikovsky

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