castanyes blaves

Random ramblings about some random stuff, and things; but more stuff than things -- all in a mesmerizing and kaleidoscopic soapbox-like flow of words.

7/02/2009

 

What a NGS IT person should be skilled in

PLoS Computational Biology: Managing and Analyzing Next-Generation Sequence Data
The skills necessary within the Facility include the following.

1.

An intimate knowledge of UNIX-based operating systems.
2.

Understanding of a scripting language such as Perl.
3.

An understanding of parallel computing environments for UNIX clusters.
4.

Knowledge of network-based data storage.
5.

General knowledge of biology and genome sciences.
6.

Ability to derive data analysis and software requirements from investigators who do not have a sophisticated understanding of information technology.
7.

Ability to develop software encapsulating new analysis methods.
8.

Understanding of relational databases and database architecture.
9.

Ability to seek out and test novel bioinformatics software and analysis routines.


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5/21/2009

 

Gene by gene turns genome-by-genome

This is a good example of the kind of paper we are probably going to see more and more often in the future:

Gene discovery using massively parallel pyrosequencing to develop ESTs for the flesh fly Sarcophaga crassipalpis
http://www.ncbi.nlm.nih.gov/pubmed/19454017

Get (a) a certain amount of RNAseq reads for your species "X", (b) build as many full-length cDNAs as possible from the fragments and (c) compare against close species in terms of:
  • New interesting cDNAs that don't have hits against existing public cDNAs -- What do they do?
  • Expression patterns -- Are these different to the patterns in other close species?
  • Protein coding evolution -- run pairwise dNdS against closest genome or tree-based dNdS against an existing phylogeny [1,2] -- Does anything show up in a Gene Ontology enrichment analysis?
Then the data is published and stored in a publicly available database, and can be added to the pool to compare against for the next project. Iterate :-)

It used to be gene-by-gene sequencing and it's now transcriptome by transcriptome sequencing. There are still sequence error and sequence coverage issues: one of my first scientific mentors, Prof. Montserrat Aguade was one of the first to do gene sequencing on the Adh gene in Drosophila when doing her PhD in Harvard. People then extended Adh sequencing and analysis to other Drosophila species, then other clades, then other genes, then some gene families like odorant binding proteins for a bunch of Drosophila species or populations, or gene pathways like the insulin pathway, etc.

But now we have a much broader picture with a rather complete transcriptome. And most of the sequencing issues are going to be corrected across the phylogeny in pretty much the same way as allele imputation is filling the gaps at the population genomics level (e.g. 1000 Genomes Project).

I am very excited about all this!

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5/01/2009

 

NCBI SRA blastn service

Never easier before to check your sequence against the NCBI Short Read Archive database:

NCBI SRA BLAST

First thoughts:
  • Transcriptome coverage is hugely biased to the 3' end (or 5' depending on library preparation). A lot more than I suspected.
  • Would be great to do queries for phylogenetic subclades: e.g. my human sequence against all SRA data for primates.
  • A lot of the 454 data has homopolymer issues, mostly TTT[...]TTTs but also some others:
Query  465  GGGCCTTGACAAAGTGTAAACCGCATGGATGGGCTTCCCC-AAGGATTTATTGACATTGC  523<br /><font color="#ff0000"><b>Sbjct</b></font>  249  ........................................<font color="#ff0000"><b>C</b></font>...................  190<br /><br /></pre><ul><li>Some of these (unless they are real variations) get picked up as mismatches, some as indels:<pre>Query  1    CGGCAAGGTATGTGCGTGATTTTGGGCCCACGTGTATTTCCATTAATTTT-AAGCCGTAA  59<br /><font color="#ff0000"><b>Sbjct</b></font>  224  ..................................................<font color="#ff0000"><b>T</b></font>.........  165<br /><br />Query  60   TTGTCGTTTTTGGCGGTTTCGAGTTGAACTGCGTTAGTCCGTGCGCTGTTCGCAAGTGTG  119<br /><font color="#ff0000"><b>Sbjct</b></font>  164  ..........<font color="#ff0000"><b>C</b></font>.................................................  105<br /></pre></li></ul><pre><br />Query  61   TGTCGTTTTTGGCGGTTTCGAGTTGAACTGCGTTAGTCCGTGCGCTGTTCGCAAGTGTGC  120<br /><font color="#ff0000"><b>Sbjct</b></font>  118  .....<font color="#ff0000"><b>C</b></font>......................................................  177<br />Query  61   TGTCG-TTTTTGGCGGTTTCGAGTTGAACTGCGTTAGTCCGTGCGCTGTTCGCAAGTGTG  119<br /><font color="#ff0000"><b>Sbjct</b></font>  160  .....<font color="#ff0000"><b>T</b></font>...............................<font color="#ff0000"><b>-</b></font>......................  102<br />Query  61   TTAATTTTAAGCCGTAATTGTCGTTTTTGGCGGTTTCGAGTTGAACTGCGTTAGTCCGTG  120<br /><font color="#ff0000"><b>Sbjct</b></font>  181  ...........................<font color="#ff0000"><b>C</b></font>................................  122<br /><br /><br /><br />


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A customized and versatile high-density genotyping array for the mouse -- Gary Churchill, The Jackson Laboratory, USA

Microarray based genotyping is an inexpensive and powerful tool to characterize genetic variation. High-density genotyping microarrays are commercially available for humans, economically important livestock and model organisms. However, they have not been available previously for the laboratory mouse, the premier mammalian model organism for biomedical research. Here we describe a custom high-density mouse genotyping array. The Mouse Diversity array was designed to capture the known genetic variation present in the laboratory mouse. It contains 623,124 SNPs distributed across the 19 mouse autosomes, the sex chromosomes, and the mitochondria with a median spacing of one SNP every 1,411 bp in the nuclear genome. The array also contains 916,269 invariant probes that are targeted to functional elements and regions of the genome known to harbor segmental duplications. The nature of the probes opens the door to a variety of novel applications including the characterization of copy number variation, allele specific gene expression and DNA methylation. Performance of the array based on call rate, replication and concordance with previously known genotypes is exceptional. The content-rich Mouse Diversity array provides a critical new tool for mouse genetics including the possibility of extending the successes of genome-wide association studies in humans to the mouse.

Funny comment -- This may be the last chip we do. The economics tell us the line is still below for chips, but sequencing is getting cheaper.

History: people catching mice, trading them, etc. Bottlenecks and all sort of artificial effects.

Diversity 11 classical inbred strains: some chromosomal regions with extremely low diversity. Is this petness? Longevity/Fecundity?

Problem with ascertainment bias: 623124 phylogenetically informative SNPs with known ascertainment

Collaborative Cross -- 8 M. musculus lines -- each contributing equally to the final "line". All inbred by now.

Phenotypes of intermediate CCs: e.g. voluntary exercise goes from 0 miles per day to 18 miles per day.

With 2 different inbred parents, we get complex children but with theoretically predictable phenotype, which means doing GWAS with phenotypes "a la carte".

Also, just by mixing genomes, creating diversity that was not in the parents: very useful novel phenotypic diversity.

Resolution is 7x better. CC will not be GWAS-level, but on the order of 10 genes or MB level resolution. Possibly gene level resolution in 10 generations. Always a mapping resolution panel and a validation panel, going back to the inbred lines.

Selection strictly by random number. Maintaining the diversity is good, lucky because natural selection already took a toll on the original strains.

Done in a way to maximise diversity, not to mimic human population structure. Deep reservoir of diversity for studying phenotypes.

A-Male/B-female crosses and compare to A-Female/B-Male in terms of sex-related epigenetics and other studies.

Some strains will die out along the way, but in 5-10 years should get a lot of info out of it.

Hyuna Yang a lot of array work.
David Aylor pop.struct.

Published mouse distances:

Mus cervicolor - Mus crociduroides = 7.60 MYA
Mus cervicolor - Mus haussa = 6.60 MYA
Mus cervicolor - Mus indutus = 6.60 MYA
Mus cervicolor - Mus mattheyi = 6.60 MYA
Mus cervicolor - Mus minutoides = 6.60 MYA
Mus cervicolor - Mus musculoides = 6.60 MYA
Mus cervicolor - Mus musculus = 4.80 MYA
Mus cervicolor - Mus pahari = 7.60 MYA
Mus cervicolor - Mus platythrix = 7.10 MYA
Mus cervicolor - Mus setulosus = 6.60 MYA
Mus cervicolor - Mus spretus = 4.80 MYA
Mus crociduroides - Mus haussa = 7.60 MYA
Mus crociduroides - Mus indutus = 7.60 MYA
Mus crociduroides - Mus mattheyi = 7.60 MYA
Mus crociduroides - Mus minutoides = 7.60 MYA
Mus crociduroides - Mus musculoides = 7.60 MYA
Mus crociduroides - Mus musculus = 7.60 MYA
Mus crociduroides - Mus pahari = 3.40 MYA
Mus crociduroides - Mus platythrix = 7.60 MYA
Mus crociduroides - Mus setulosus = 7.60 MYA
Mus crociduroides - Mus spretus = 7.60 MYA
Mus haussa - Mus indutus = 3.20 MYA
Mus haussa - Mus mattheyi = 2.60 MYA
Mus haussa - Mus minutoides = 3.20 MYA
Mus haussa - Mus musculoides = 3.20 MYA
Mus haussa - Mus musculus = 6.60 MYA
Mus haussa - Mus pahari = 7.60 MYA
Mus haussa - Mus platythrix = 7.10 MYA
Mus haussa - Mus setulosus = 4.00 MYA
Mus haussa - Mus spretus = 6.60 MYA
Mus indutus - Mus mattheyi = 3.20 MYA
Mus indutus - Mus minutoides = 2.50 MYA
Mus indutus - Mus musculoides = 2.50 MYA
Mus indutus - Mus musculus = 6.60 MYA
Mus indutus - Mus pahari = 7.60 MYA
Mus indutus - Mus platythrix = 7.10 MYA
Mus indutus - Mus setulosus = 4.00 MYA
Mus indutus - Mus spretus = 6.60 MYA
Mus mattheyi - Mus minutoides = 3.20 MYA
Mus mattheyi - Mus musculoides = 3.20 MYA
Mus mattheyi - Mus musculus = 6.60 MYA
Mus mattheyi - Mus pahari = 7.60 MYA
Mus mattheyi - Mus platythrix = 7.10 MYA
Mus mattheyi - Mus setulosus = 4.00 MYA
Mus mattheyi - Mus spretus = 6.60 MYA
Mus minutoides - Mus musculoides = 1.60 MYA
Mus minutoides - Mus musculus = 6.60 MYA
Mus minutoides - Mus pahari = 7.60 MYA
Mus minutoides - Mus platythrix = 7.10 MYA
Mus minutoides - Mus setulosus = 4.00 MYA
Mus minutoides - Mus spretus = 6.60 MYA
Mus musculoides - Mus musculus = 6.60 MYA
Mus musculoides - Mus pahari = 7.60 MYA
Mus musculoides - Mus platythrix = 7.10 MYA
Mus musculoides - Mus setulosus = 4.00 MYA
Mus musculoides - Mus spretus = 6.60 MYA
Mus musculus - Mus pahari = 7.60 MYA
Mus musculus - Mus platythrix = 7.10 MYA
Mus musculus - Mus setulosus = 6.60 MYA
Mus musculus - Mus spretus = 2.30 MYA
Mus pahari - Mus platythrix = 7.60 MYA
Mus pahari - Mus setulosus = 7.60 MYA
Mus pahari - Mus spretus = 7.60 MYA
Mus platythrix - Mus setulosus = 7.10 MYA
Mus platythrix - Mus spretus = 7.10 MYA
Mus setulosus - Mus spretus = 6.60 MYA


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4/30/2009

 

RNAseq in the worm -- Gary Williams

Illumina Short-read transcriptome data has the potential to help solve many problems with curating gene models and the genomic sequence in C. elegans. This is an initial look at the data and some examples of how it can be used.

So far, C. elegans gene predictions:

36% - fully confirmed by ESTs
48% - partially confirmed
14% - no transcript confirmation

RNAseq data -- different worms than the genome, so some polymorphisms expected -- 200bp inserts, 36bp paired end reads

MAQ or cross-match to genomic or transcript sequences

6137 new splice junctions (6% increase)

Jumped from 70000 to 98000 splice junctions.
3x as many polyA sites
80 possible new coding genes

V-shaped coverages -- validation against traces, then:
  • Detected sequencing error, correction needed for the reference
  • Detected alternative haplotype
Moving towards single-cell sequencing -- not sequencing in tiny cells but sequencing each cell in each developmental state in the worm. Moving towards RNA sequencing C. briggsae and C. remanei.

Updated gene builds will be given to other projects. Next Ensembl Metazoa comparative genomics build may already have the modENCODE-updated C. elegans and D. melanogaster builds.

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4/07/2009

 

Promoting Open Source Bioinformatics

Interesting to see all the buzz that the Benjamin Franklin Award has generated in the blogosphere, twittersphere, facebooksphere and any of the other spheres out there... I still think there is something we should try and resolve in open source bioinformatics, which is promoting Open Source software to create more awareness in the scientific community. We need to reconcile the promotion of modularity and generality with the fact that giving credit to the scientists who contribute to Open Source Bioinformatics software is still important. Projects that have built very modular and generic components may be doing a lot for the bioinformatics community at large but, at the same time, the less atomic and single-purpose your software is, the more difficult it is to publish it in a prominent scientific journal. The same goes for citing it in the downstream publications: very atomic programs are very successful in citation metrics, but infrastructure code is not. This means that well-designed, well-implemented and well-tested software is often not prominent enough for new people to notice, and too many bioinformaticians resort to their own glue code for building their bioinformatics infrastructure.

There wouldn't be anything wrong with rewriting your own code over and over again if it weren't because: (a) people spend too much time writing scaffolding code that will let them access what is really new and interesting in their project and (b) that code tends to be used and tested only internally and almost never reused for any other party unless it has been very well designed and documented --- hence the name scaffolding code.

There is a really good chance now to build an infrastructure that brings up a terminal next to the next generation Petabyte-size data sources, using emerging "cloud" technologies. These technologies are already advanced in other fields other than bioinformatics, so we can leverage what it has already been done for us and make extensive use of it. These terminals don't need to be silly, and the community should provide in them as much prebuilt code as possible so that the new breed of bioinformaticians get used to have this software at their fingertips.

A few years ago all the effort was in building packages for different Linux distributions, so that people could easily install Open Source software on their in-house CPU clusters. I think we need to shift gears now to cloud software accessibility. The good news is that it seems everybody is happy with the common Ubuntu system as a start. I fear the proliferation of iPhone-like SDKs around that will make the existing bioinformatics software useless. In an era where everybody is acutely aware about governments having to pour our taxes into infrastructure that was already paid for, noone will like to see all existing bioinformatics software become a "toxic" or "legacy asset"!

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3/26/2009

 

Jalview Google Summer of Code 2009

(Shameless plug of the day)

There is an opportunity for students to propose a Jalview
related software development project as part of the Google Summer of
Code this year, with an stipend of $4500. This project would be
supported by the NESCent mentor organisation, and ideally improve
Jalview's phylogenetic analysis capabilities, enhance the applet's use
as an AJAX web gui component, and/or extend its visualization and
editing capabilities for use as a curation tool.

The application period for student proposals is rapidly approaching, and
its important to discuss proposals with mentors before submission. If
you or anyone you know are interested, please read and/or forward the
message below, and look at the jalview project section on the following
(huge) URL:

http://www.nescent.org/wg/phyloinformatics/index.php?title=Phyloinformatics_Summer_of_Code_2009#Extend_Jalview_Alignment_visualization_tool


Regards.
Albert Vilella.
----

PHYLOINFORMATICS SUMMER OF CODE 2009

http://hackathon.nescent.org/Phyloinformatics_Summer_of_Code_2009

The Phyloinformatics Summer of Code program provides a unique
opportunity for undergraduate, masters, and PhD students to obtain
hands-on experience writing and extending open-source software for
evolutionary informatics under the mentorship of experienced
developers from around the world. The program is the participation of
the US National Evolutionary Synthesis Center (NESCent) as a
mentoring organization in the Google Summer of Code(tm) (http://
code.google.com/soc/).

Students in the program will receive a stipend from Google (and
possibly more importantly, a T-shirt solely available to successful
participants), and may work from their home, or home institution, for
the duration of the 3 month program. Each student will have at least
one dedicated mentor to show them the ropes and help them complete
their project.

NESCent is particularly targeting students interested in both
evolutionary biology and software development. Initial project ideas
are listed on the website. These range from hardware accerelation for
phylogenetic inference, to tree visualization within a wiki, to
alignment of next-gen sequencing data, to development of a reusable
ontology term markup module for biocuration. All project ideas are
flexible and many can be adjusted in scope to match the skills of the
student.  We also welcome novel project ideas that dovetail with
student interests.

TO APPLY: Apply online at the Google Summer of Code website (http://
socghop.appspot.com/), where you will also find GSoC  program
rules and eligibility requirements.  The 12-day application period
for students opens on Monday March 23rd and runs through Friday,
April 3rd, 2009.

INQUIRIES: phylosoc {at} nescent {dot} org. We strongly encourage all
interested students to get in touch with us with their ideas as early
on as possible.

2009 NESCent Phyloinformatics Summer of Code:
http://hackathon.nescent.net/Phyloinformatics_Summer_of_Code_2009

Google Summer of Code FAQ:
http://socghop.appspot.com/document/show/program/google/gsoc2009/faqs

Cyberinfrastructure Traineeships (managed separately from GSoC;
postdocs also eligible):
http://hackathon.nescent.org/
Cyberinfrastructure_Summer_Traineeships_2009

To sign up for quarterly NESCent newsletters: http://www.nescent.org/
about/contact.php

---------

Todd Vision and Hilmar Lapp
National Evolutionary Synthesis Center
http://nescent.org

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3/23/2009

 

Laura Clarke - 1000 Genomes project

Depositing every week same amount of data as all was in public dbs before (past ~20-30 years).

Data coordination (EBI Paul Flicek, Laura+Zam). Keep submissions, run QCs and recalibration, present in mini Ensembl browser. Working on the Resembl (Solexa) public release, need to implement as MySQL 5.1 partitioning instead of commercial db.

Pipeline -- first align to the genome; will move to new assembly soon. 454 with ssaha, Solexa here with MAQ.

Trios data now being churned at dbSNP -- causing dbSNP more churning than usual releases, they are catching up. Low coverage also submitted, but will probably be in dbSNP 131.

Data formats: Fastq / BAM (binary SAM alignment map format) / GLF (genotype likelihood format). BAMs/GLFs will be updated as more data gets in and old ones will disappear.

Hope all the sequencing will be done by the end of 2009. Paper about pilot projects soon. Targetted sequencing (pilot 3) took more time, pull-down methods a bit longer to nail down, now working.

DCC more automated data delivery systems. Standard QC/Recalibration pipeline. Other high throughput analyses. New staff. May take over the alignment process once the alignment algorithm is consensuated.

Jim Stalker and Thomas Keane doing a lot of work at the Sanger. Eugene Kulesha and Stephen Keenan on the website work. Fiona and Yuan on calling/storing/presenting SNPs in Ensembl.

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3/21/2009

 

Browse the NCBI Short Read Archive by taxonomy

Here is the link.

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3/20/2009

 

Next Generation community resources for Next Generation Sequencing

I've been looking at SEQanswers lately to try and discern where is people drawing the "Here be dragons" of their research. A lot of it is about wet lab protocols, which is great news, because it means the discoveries in different labs are shortcutting publication delays and being adopted as soon as possible. But there is also a lot of data analysis discussions which is great to identify the needs for specific bioinformatics tools in the outside world. It is becoming increasingly important in new emerging IT fields to know what *not* to work on other than what to work on, and forums like SEQanswers are great for this.

Great seeing people using this forum and not being afraid of showing results --- which is also showing muscle sometimes, but all good and fair. I wonder how much of this is known by lab bosses and how much of potentially old generation bosses understand of these Internet open community practices...

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3/18/2009

 

The blurring line between protein alignments and genomic alignments

As more and more data is being poured into the public sequence databases, an increasingly detailed map is being drawn that relates sequences from different individuals or different species, mainly into what has been known in the field as protein or genomic (DNA) alignments. This is what one can call twenty-first century molecular cartography.


All references to molecular evolution this year should be accompanied with an analogy to Darwin's work, so here is how it works in this case: Darwin's next generation machine, the Beagle, went on a journey to accumulate an enormous variety of specimens that, when compared all together, allowed Darwin to draw the first phylogenetic tree.


Contrary to what one would think, alignments with more sequences are easier to resolve than ones with less sequences, at least when the phylogenetic tree relating the sequences increases in detail, which is almost always. And this is allowing researchers to generate genomic alignments for phylogenetically dense groups of genomes while, in parallel, the protein alignments for the corresponding protein coding genes in these genomes are combined together with more distantly related species. This dense taxon sampling is making the distinction between protein alignments and genomic alignments less and less obvious.


As an example, one can use the highly conserved protein coding exons to anchor the points in the different chromosomes that define stretches of conserved synteny among the genomes, and then align these DNA stretches all together with a genomic aligner. At the same time, one can use the exon boundaries defined in the DNA sequences of the coding genes to help infer the right protein alignment at the aminoacidic level.


A new opportunity is now arising in exploiting the information that is contained separately in the genomic and protein alignments to combine them into a single object representing both. New methods are being developed that will exploit the landmarks that both genomic and protein alignments have correctly place to converge into a single intertwined alignment object. This new type of alignment has in a way already been represented in closely related prokaryotic genomes. But prokaryotic genomes are less interesting for some topics, like alternative splicing, repetitive elements or recombination hotspots. Combined genomic and protein alignments will bring new elements of detail together that have been scattered so far for researchers to study and hopefully some new and brilliant mechanistic explanations of the innards of molecular evolution will arise from them, in the same way that Darwin did two centuries ago.


So a deluge of sequencing data is not really a problem but an opportunity.



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2/18/2009

 

Not there yet for complicated genomes

BioMed Central | Full text | Assessing the feasibility of GS FLX Pyrosequencing for sequencing the Atlantic salmon genome
[...] the addition of GS FLX Paired End reads vastly improved the capability of 454 pyrosequencing by enabling the assembly of contigs into large scaffolds. Indeed, in terms of the number of scaffolds produced, the GS FLX assembly that included the combined shotgun and paired end reads was comparable to the Sanger assembly. Moreover, the order of the GS FLX scaffolds could be established from information from BAC-end sequences and the Atlantic salmon physical map. However, numerous gaps remained within the scaffolds, which is undesirable when a complete or reference genome sequence is one of the goals. Currently, if the Atlantic salmon genome is to provide a reference sequence for all salmonids, then a substantial proportion of the sequencing will have to be carried out using Sanger technology.


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