scholarly journals A tunable filter for high molecular weight DNA selection and linked-read sequencing

Lab on a Chip ◽  
2020 ◽  
Vol 20 (1) ◽  
pp. 175-184 ◽  
Author(s):  
Nicolas Milon ◽  
Juan-Luis Fuentes Rojas ◽  
Adrien Castinel ◽  
Laurent Bigot ◽  
Géraud Bouwmans ◽  
...  

In third generation sequencing, long DNA molecules of more than ∼20 kbp are needed to obtain quality sequence data. Here we report a versatile technology for DNA size selection that fulfills this requirement.

2020 ◽  
Author(s):  
Rhosener Bhea Lu Koh ◽  
Cris Francis Cortez Barbosa ◽  
Vermando Masinsin Aquino ◽  
Leny Calano Galvez

Abstract Background The abaca (Musa textilis Née) is a fiber crop native to the Philippines with high economic value because of its fiber - the Manila hemp, known to be the strongest of all the natural fibers. DNA extraction in abaca is difficult due to its fibrous nature, high cellulose content and polyphenol compounds. Thus an optimized DNA extraction method is required for extracting high quality abaca DNA for next-generation sequencing applications. Results In this study, we have compared five different methods for the extraction of high molecular weight DNA from abaca leaves. The methods are the traditional CTAB method (Protocol 1), the CTAB with PVP method (Protocol 2), the CTAB with 0.3% β-mercaptoethanol method (Protocol 3), SDS-method (Protocol 4) and CTAB with Triton X-100 and PVP method (Protocol 5). Out of the five methods tested, traditional CTAB-method (Protocol 1), CTAB with 0.3% β-mercaptoethanol method (Protocol 3) and SDS-method (Protocol 4) have shown to be the most consistent in giving high molecular weight DNA with good yield and purity based on A260/A280 and A260/A230 absorption values. TissueLyserII was also utilized for homogenization for the three extraction protocols for applications in high-throughput DNA extraction. DNA from two abaca varieties were extracted using the CTAB with 0.3% β-mercaptoethanol method (Protocol 3) and were sent for NGS based on Illumina HiSeq platform having both passed the quality control for library preparation. Conclusion The CTAB with 0.3% β-mercaptoethanol method (Protocol 3) was found to be the simplest and most consistent method for extracting average yield DNA with high quality for NGS applications. The SDS-method (Protocol 4) was determined to have the shortest processing time and together with TissueLyserII is the most appropriate method for high-throughput extraction of abaca samples which will be useful for genotyping-by-sequencing (GBS) studies.


PLoS ONE ◽  
2021 ◽  
Vol 16 (7) ◽  
pp. e0253830
Author(s):  
Ashley Jones ◽  
Cynthia Torkel ◽  
David Stanley ◽  
Jamila Nasim ◽  
Justin Borevitz ◽  
...  

Rapid advancements in long-read sequencing technologies have transformed read lengths from bps to Mbps, which has enabled chromosome-scale genome assemblies. However, read lengths are now becoming limited by the extraction of pure high-molecular weight DNA suitable for long-read sequencing, which is particularly challenging in plants and fungi. To overcome this, we present a protocol collection; high-molecular weight DNA extraction, clean-up and size selection for long-read sequencing. We optimised a gentle magnetic bead based high-molecular weight DNA extraction, which is presented here in detail. The protocol circumvents spin columns and high-centrifugation, to limit DNA fragmentation. The protocol is scalable based on tissue input, which can be used on many species of plants, fungi, reptiles and bacteria. It is also cost effective compared to kit-based protocols and hence applicable at scale in low resource settings. An optional sorbitol wash is listed and is highly recommended for plant and fungal tissues. To further remove any remaining contaminants such as phenols and polysaccharides, optional DNA clean-up and size selection strategies are given. This protocol collection is suitable for all common long-read sequencing platforms, such as technologies offered by PacBio and Oxford Nanopore. Using these protocols, sequencing on the Oxford Nanopore MinION can achieve read length N50 values of 30–50 kb, with reads exceeding 200 kb and outputs ranging from 15–30 Gbp. This has been routinely achieved with various plant, fungi, animal and bacteria samples.


Author(s):  
P.D.N. HEBERT ◽  
◽  
T.W.A. BRAUKMANN ◽  
S.W.J. PROSSER ◽  
S. RATNASINGHAM ◽  
...  

2020 ◽  
Vol 15 ◽  
Author(s):  
Hongdong Li ◽  
Wenjing Zhang ◽  
Yuwen Luo ◽  
Jianxin Wang

Aims: Accurately detect isoforms from third generation sequencing data. Background: Transcriptome annotation is the basis for the analysis of gene expression and regulation. The transcriptome annotation of many organisms such as humans is far from incomplete, due partly to the challenge in the identification of isoforms that are produced from the same gene through alternative splicing. Third generation sequencing (TGS) reads provide unprecedented opportunity for detecting isoforms due to their long length that exceeds the length of most isoforms. One limitation of current TGS reads-based isoform detection methods is that they are exclusively based on sequence reads, without incorporating the sequence information of known isoforms. Objective: Develop an efficient method for isoform detection. Method: Based on annotated isoforms, we propose a splice isoform detection method called IsoDetect. First, the sequence at exon-exon junction is extracted from annotated isoforms as the “short feature sequence”, which is used to distinguish different splice isoforms. Second, we aligned these feature sequences to long reads and divided long reads into groups that contain the same set of feature sequences, thereby avoiding the pair-wise comparison among the large number of long reads. Third, clustering and consensus generation are carried out based on sequence similarity. For the long reads that do not contain any short feature sequence, clustering analysis based on sequence similarity is performed to identify isoforms. Result: Tested on two datasets from Calypte Anna and Zebra Finch, IsoDetect showed higher speed and compelling accuracy compared with four existing methods. Conclusion: IsoDetect is a promising method for isoform detection. Other: This paper was accepted by the CBC2019 conference.


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