Inference and informatics in a 'sequenced' world
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Short lecture relating my recent work on real-time phylogenomics, implications for bioinformatics research and future directions of genomic/phylogenetic modelling to explicitly account for phylogeny, synteny and identity through coloured graphs. University of Reading, 2nd August 2017
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Inference and informatics in a 'sequenced' world
- 1. Informatics and inference in a sequenced world Dr. Joe Parker Early Career Research Fellow (Phylogenomics) Royal Botanic Gardens, Kew @lonelyjoeparker:
- 2. Joe Parker - background 2 VL 4 length Average VL 1 length ≤ 3 4 ≤ 2 7 > 2 7 > 3 4 Neut - Neut +
- 3. Incredible times for bioscience 3 Images – Wikimedia commons CC BY-SA (clockwise from top left: Jeroen Rouwkema, @aGastya, author’s own, @RE73)
- 4. Step back: molecular evolution 4 “Horizontal gene transfer occurs x more frequently in these lineages, because of this biology” “Convergent evolution is rare in most genes, in most organisms, but y times greater in these gene families …because of this biology” “New chomosomes are created & destroyed at z, q, rates in this reproductive strategy …because of this biology”
- 6. Snowdonia, HelloWorld & ‘tent-seq’ 6 A. thaliana Arabidopsis lyrata Congeneric species; Reference genomes available Field-sequenced (MinION) & Lab-sequenced (Illumina™) Orthogonal BLAST: 4 sample*sequencer combinations Compare TRUE & FALSE rates for varying ID statistic cutoffs
- 7. Tasty pics 7 Conditions 100% humidity; 6-13ºC Essential kit 800w generator 3x laptops Centrifuge Waterbath Polystyrene boxes (lots) Kettle(…!) Yield >400Mbp data in three days; A. thaliana ~2.01x coverage
- 8. Field- vs. lab-sequenced sample ID 8 Match individual reads to each reference with BLAST Compare match lengths in TRUE and FALSE cases ‘Length bias’ ID stat: lengthTRUE - lengthFALSE Compare TRUE & FALSE rates as length bias cutoff varies MiSeq (lab) MinION (field)
- 9. Bitty data (1) partial queries 9 Subsample MinION output Repeat ID pipeline, record mean ID stat sbias Replicates: N = 30 Simulate from 100 – 104 reads (≈instant → hours)
- 10. Bitty data (2) partial references 10 Take reference genome at high contiguity Fragment randomly to target (low) contiguity Repeat read identification using fragmented DB Simulate N50 ≈1,000bp to N50 ≈ 10Mbp
- 11. Keeping it simple: Kew Science Festival 11 Six species: whole genome- skim samples with MinION in preparation Build BLAST DBs from skimmed data Select ‘unknown’ (blinded) sample, extract DNA and resequence in real-time Compare to partial DBs in six- way BLAST competition Live ID ?
- 12. de novo genome assembly 12 Data MiSeq only MiSeq + MinION Assembler Abyss hybridSPAdes Illumina reads, 300bp paired-end 8,033,488 8,033,488 Illumina data (yield) 2,418 Mbp 2,418 Mbp MinION reads, R7.3 + R9 kits, N50 ~ 4,410bp - 96,845 MinION data (yield) - 240 Mbp Approx. coverage 19.49x 19.49x + 2.01x Assembly key statistics: # contigs 24,999 10,644 Longest contig 90 Kbp 414 Kbp N50 contiguity 7,853 bp 48,730 bp Fraction of reference genome (%) 82 88 Errors, per 100 kbp: #N’s 1.7 5.4 # mismatches 518 588 # indels 120 130 Largest alignment 76,935 bp 264,039 bp CEGMA gene completeness estimate: # genes 219 of 248 245 of 248 % genes 88% 99%
- 13. Wait – genes? 13 Entire chloroplast genome (~150kbp) Plastid coding loci Individual field- sequenced MinION reads
- 14. Real-time phylogenomics 14 Filtered reads Gene models TAIR10 CDS code Annotation SNAP 1:1 reciprocal BLAST Multiple sequence alignments MUSCLE Trimal Gene trees → Consensus tree *BEAST RAxML, TreeAnnotator Cumulative counts: Unique genes All genes (‘Lab’ being transported!)
- 15. Emerging health threats & globalisation 15 Acute oak decline: A syndrome-type oak disease • Unknown cause, no treatment • ca. 200 million oaks in GB …amenity & timber value: ~£500/tree • Emerged ca. 2004, spreading rapidly • Significant morbidity and mortality Defra ‘Futureproofing Plant Health’ initiative • Test field-based methods • Balanced survey of microbial community composition (healthy & affected individuals) • Overcome ascertainment bias • Pilot training of non-experts. • Draw conclusions relevant to rapid-response plant health monitoring in the UK. © 2016 Katy Reed / Forest Research
- 16. Recap 16 From lab-based… … to ‘app store’ genomics
- 17. Problems with phylogeny… and comparative genomics 17 Suh (2016) Zool. Scripta. doi:10.1111/zsc.12213 Zapata et al. (2016) PNAS 113:E4052-E4060 ©2016 National Academy of Sciences
- 18. Key: Extant node Inferred node Synteny edge (physical connection Phylogeny edge (evolutionary connection) Identity edge (organismal connection) Three-colour graphs: phylogeny, synteny & identity 18 a b c d x y z e a a
- 19. Three-colour graphs: phylogeny, synteny & identity 19 a1 b1 a2 b2 a3 b3 b’3 a4 b4 a5 b5 Duplication a1 b1 a2 b2 a3 b3 a4 b4 x4 y4 x3 y3 x1 y1x2 Tetraploid hybrid formed Diploidization Key: Extant node Inferred node Synteny edge (physical connection) Phylogeny edge (evolutionary connection) Identity edge (organismal connection)a1 b1 b2 a2 a3 b3 c1 c3 c1 Inversion a1 b1 a2 b2 x1 x5 x2 x3 x4 x7 x6 HGT
- 20. Final thoughts 20 bionode.js bioboxes.org Singularity Portable sequencing, by anyone means really Big Data Informatics connecting this data through explicit models is inference Scalable, reproducible, sustainable research:
- 21. Thanks, funders, contacts and questions 21 Oxford Nanopore Technologies Ltd. Dan Turner, Richard Ronan, Gerrard CoyneRBG Kew: Alexander S.T. Papadopulos (@metallophyte) Andrew Helmstetter (@ajhelmstetter) Dion Devey, Robyn Cowan, Tim Wilkinson, Stephen Dodsworth, Pepijn Kooij, Felix Forest, Bill Baker, Jan T. Kim, Jenny Williams, Abigail Barker, Mark Lee, Jim Clarkson, Mike Chester, Ester Gaya, Lisa Pokorny, Laszlo Csiba, Paul Wilkin, Richard Buggs, Mike Fay, Mark Chase, Ilia Leitch QMUL Laura Kelly, Kalina Davies, Steve Rossiter Oxford Aris Katzourakis, Oli Pybus, Jayna Raghwani Others Forest Research: Daegan Inward, Katy Reed Dstl: Claire Lonstale, James Taylor Birmingham: Nick Loman, Josh Quick U. Utah: Bryn Dentinger Imperial: James Rosindell This research was conducted in the Sackler Phylogenomics Laboratory and was supported by the Calleva Foundation Phylogenomic Research Programme and the Sackler Trust @lonelyjoeparker: joe.parker@kew.org
Notas del editor
- Welcome, thanks, menu Formal introduction and thanks; Lay out the menu / journey I’ll mainly be talking about work in the last 2.5 yrs since taking up my ECRF at Kew
- Wide range of taxa, techniques and questions. Enough to set my scene without taking ages, confusing/losing audience, or giving the impression I’m just a tools-bot.
- Start of… Incredible times Traditional to start bioinformatics talks with a slide about Moore’s law, sequencing costs, and the data deluge Actually this is a fantastic age to be living in, ever bigger analyses – and I’ll talk a lot about “real-time” phylogenomics But why? What are we attempting to discover?
- We need enough data to turn obervations, into empirical comparisons, into models and laws We know a lot about evolutionary mechanisms And a lot about (a handful of genomes) What we know tells us “it’s complicated” Most genes don’t have simple orthologues etc etc etc, hotizonatl etc But we don’t, really, have an empirical understanding of how they fit together, e.g.: - ”horizontal gene transfer occurs x more frequently in these lineages, because of this biology” - adaptive molecularconvergence is rare in most genes, in most organisms, but y times greater in these gene families because of this biology - new chomosomes are created (by duplication, endogenisation, polyploidy) and destroyed (by diploidization) at z rates in this reproductive strategy because of biology
- Portable sequencing: also long reads and real-time
- Direct, explicit, orthogonal test – and can it work? Picture of experimental design Outline of the study In terms of bioinformatics questions Funding: a first pot and timeline…
- Data in terrible conditions but anyone can do it Social media reach The Atlantic, Economist
- We compare match lengths, and minon allows long matches
- EXPLAIN AXES: precision improves rapidly
- EXPLAIN AXES: a partial REFERENCE would work, too
- MORE FUNDING. SO simple a kid could do it? Yes The challenge I set myself: OK, it’s a simple experiment. Can I buid a trest simple ehough a child can understand it? SOCIAL MEDIA Funding: NANOPORE
- Data from one time and place can and should be useful elsewhere lash a bit of proper genomics
- Single reads match whole genes – meat & drink
- EXPLAIN AXES postdoc-years PAPER ACCEPTED
- FUNDED tailor made for health research/application need to mention it somewhere because of: strategic links Building the ‘momentum narrative’ Other related stuff; VIPs etc Plant health and emerging threats A connected world means new diseases can spread globally, fast. Lay out the problem, e.g. opportunities – look! Health! Ascertainment bias! Field-portable! etc Funding: yet another pot, this one also bigger. Software etc to improve UI (ahem)
- HPCs to apps: Exponential data, linear understanding. Pause – to recap This is important because it’s where we tie it together and show my contribution: Portable, mass sequencing is really here Massive potential for de novo genomics; phylogenomics But while we’re accumulating information at an exponential rate, we’re integrating it linearly, in essence … where are we going?
- Nature is cruel: more data only muddies the water Bifurcating phylogenies are decreasingly useful and complicated to get ‘Comparative’ genomics actually uses relatively few datapoints (e.g. Encode…) In part because most phylogenetic methods require variations on homology assumption
- Here’s a common framework for all these studies How to infer – sounds like a nightmare Many of the edges in this network are really there already Shifting paradigms, making linking easier Explicitly model phylogeny, synteny and identity Edge support reflects evidence; deviations from neutrality reflect hypotheses/models/phenomena Any nodes connecting to an identity edge are considered completely connected Maximum # edges ~n (2n-1)/2 Digraphs ~n!! Possible ancestors from one locus on n taxa essentially inverse func of when they coalesce (can have m generations of n ancestors until an event where n(m)<n(t)
- EXAMPLES Gene duplication e.g. paralogue in animal Tetraploid formed then secondary diploidization, e.g. plant Inversion in a genome Unlinked loci (e.g. bacterial plasmids) and HGT. How to infer – sounds like a nightmare Many of the edges in this network are really there already Shifting paradigms, making linking easier Explicitly model phylogeny, synteny and identity Edge support reflects evidence; deviations from neutrality reflect hypotheses/models/phenomena
- Formally linking datasets and models is inferring the network of life Shifts the job for bioinformatics from something it’s good at – sophisiticated analysis incemental To sometheing computers in gerneral are great at: linking elements In this case informatics doesn’t enable research , it is the process of inference It’s relatively easy to write a new standalone app to do x, or analyse some big dataset Reproducibility and scaling-up science mean we must work harder on the links Informatics as inference. The lonely astronomers.
- Funders Thanks Reach out