Iso-Seq学习

时间:2023-03-09 15:05:29
Iso-Seq学习

SMRT portal安装教程:

http://www.pacb.com/wp-content/uploads/2015/09/SMRT-Analysis-Software-Installation-v2.3.0.pdf

ISO-seq数据地址:

/share/backups/pacbio/20160222_68 的 A01 和 B01。

<1kb的得到1.28G数据,>1kb的得到了2.8G的数据。

SMRT portal 地址:

Iso-Seq学习http://59.79.232.10:8080/smrtportal/#/Design-Job/
软件安装主目录:
/share/workplace/software/PACBIO

reference_droplist: :

/share/workplace/software/PACBIO/userdata/references_dropbox

username: pbuser
password: pacbio-one2three

学习目的:对这两个cell收集一下结果(多少reads,多少全长reads,多少isoform,SMRT-portal的报告都有。

ISOseq数据比对到参考基因组

文本教程参见:
视频教程:

THE CHALLENGE OF ISOFORM RECONSTRUCTION

简单的说就是二代测序无法有效区分同一个transcript的单倍型!

In eukaryotic organisms, the majority of genes are alternatively spliced to produce multiple transcript isoforms, dramatically increasing the protein-coding potential of a genome.

Alternatively spliced isoforms from the same gene can have significantly different, even antagonistic, effects. To study gene expression, researchers have looked at fragments of an organism’s genes utilizing next-generation sequencing methods, commonly referred to as RNA sequencing (RNA-seq). However, short-read RNA-seq cannot span full-length transcripts, making it difficult to accurately characterize the diverse landscape of isoforms.

Produce full-length transcripts without assembly

简单的说就是三代测序能直接把一个单倍型测穿。这就是ISOseq

The isoform sequencing (Iso-Seq) application generates full-length cDNA sequences — from the 5’ end of transcripts to the poly-A tail — eliminating the need for transcriptome reconstruction using isoform-inference algorithms. The Iso-Seq method generates accurate information about alternatively spliced exons and transcriptional start sites. It also delivers information about poly-adenylation sites for transcripts up to 10 kb in length across the full complement of isoforms within targeted genes or the entire transcriptome.

Iso-Seq的目的就是: understand transcriptome complexity using accurate, unassembled, full-length long reads.

Iso-Seq学习

实验室测序出来的数据目录结构:

Iso-Seq学习

Analysis_Results下的文件:

Iso-Seq学习

正确的数据结构如下:

注意metadata.xml文件和子目录下的bax.h5文件。

Iso-Seq学习

对于数据的处理有三种方式,一种是通过RS_isoseq SMRT portal, 一种是github code,一种是RS_isoseq 明令行。三者的主要区别如下:

The differences between the GitHub code and the RS_IsoSeq code are:

  • GitHub code requires you to set up a virtual environment and install all libraries on your own
  • GitHub code is more step-by-step and allows more flexibility
  • GitHub code is updated faster
  • GitHub code is all source code - you can modify the code as needed

The difference between the SMRT Portal version and the command-line version (pbtranscript.py) is that the command-line version additionally allows you to:

  • Use more CPUs than default
  • Directly start from the isoform-level clustering (ICE) part of RS_IsoSeq. Since v2.3.0, we have added additional entry points to the ICE/Quiver pipeline.

如果用SMRT portal 来分析数据,步骤如下:

1, getting FL reads

首先导入你的raw data,然后选择RS_IsoSeq protocol(SMRT PORTAL的版本要v2.3.0以上)

具体操作参见以前写的博客。(http://www.cnblogs.com/freemao/p/3783475.html)

Iso-seq 建库流程:

Iso-Seq学习

扫盲几个概念:

reads of insert 和 FL reads:

Iso-Seq学习

建库的时候可能会产生artificial chimeras,分两种:

第一种是接头浓度低导致的:

Iso-Seq学习

第二种是PCR扩增时导致的:

Iso-Seq学习

所以最终的数据:

Iso-Seq学习

下一步:

Iso-Seq学习

为何要进行上面的步骤:

Iso-Seq学习

Iso-seq的整个生物信息学分析流程大概就是这样的:

Iso-Seq学习

主要是两部分:1是classify, 2是cluster

classify 识别FL reads

cluster 主要是performs isoform-level clustering and outputs Quiver-polished high-quality consensus full-length transcript sequences.

整个过程是不需要参考基因组的,如果有参考基因组,可以被用来做比对,把polished transcipts map上去。从而可以

①,去除redundancy(Iso-Seq cluster output can be redundant).如下图:

Iso-Seq学习

去除冗余应用实例:

Iso-Seq学习

Iso-Seq学习

②,可以发现新的基因或者isoforms.

classify 和 cluster的比较如下:

Iso-Seq学习

运行classify 和 cluster既可以在SMRT Portal,也可完全用命令行(pbtranscript.py),TOFU. 使用帮助在(https://github.com/PacificBiosciences/cDNA_primer/wiki)

关于最后的isoform结果 可以通过UCSC browser看一下,肯定是要比二代的效果好很多。

Iso seq的应用:

1, Transcript indentification and annotation

2,  Identification of Alternatively spliced isoforms

3,  Targeted sequencing

4, normalization reduces the representation of highly expressed genes.

后续可以做的分析有(根据你自己的项目而定):

Iso-Seq学习

详情见2015 webinar 文档。

学习网站:

•Iso-Seq Website (general information):
•Iso-Seq Analysis Information:
•Protocols:
•Available Datasets:
–MCF-7 Cancer Cell Line
–Human Normal Tissues (Brain, Heart, Liver)
Library and Sequencing Evaluation 步骤:
Iso-Seq学习
结果表格如下:
Iso-Seq学习
 任务过程:
http://59.79.232.10:8080/smrtportal/#/Design-Job/
import and manage
import SMRT cells
add...
/share/backups/pacbio/20160222_68/A01_1
scan...OK
/share/backups/pacbio/20160222_68/B01_1
scan...OK
Design Job
Creat new
Analysis 对话框全部打钩
Next
填写Job Name
Protocals 选择 RS_IsoSeq.1
将YM1-30pM和YM2-30pM 这两个样导入,如果不知道哪个是你的数据,就看Uri那一列,有数据的位置。
save
start
任务就开始跑了 
可以到melon上 执行 qstat -a查看任务状态 也可以直接在网页上monitor查看
freemao
FAFU
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