We are pleased to announce the 12th release of WormBase ParaSite, bringing new and updated genomes, and better handling of old identifiers and history.
New and updated genomes
There are also new clade IV nematode genomes: root-knot nematodes Meloidogyne graminicola (PRJNA411966) and Meloidogyne arenaria (PRJNA438575) (alternative assembly), and a bacteria-feeding Acrobeloides nanus (PRJEB26554).
The rest of the updates are:
- annotation update to Ancylostoma ceylanicum (PRJNA72583)
- updating WormBase core species B. malayi and C. briggsae to WS267 (with C. elegans and T. muris still corresponding to version WS265 due to our omission – we apologise!)
- about a 100 updated gene models for Schistosoma mansoni (PRJEA36577)
- fixed typo in the name of Oscheius tipulae (PRJEB15512) (Oschieus -> Oscheius)
- renamed genes for Plectus sambesii (PRJNA390260), from names like “g2” to names like “PSAMB.scaffold2size251193.g730”
Data and tools
We have re-ran our comparative genomics pipeline, constructing gene trees and finding orthologs and homologs. We have also reran newest InterProScan (5.30-69.0) and our cross-references pipeline for all our genomes.
We re-imported all public RNASeq data from our collaborators, and did a round of minor improvements to the displays. We now use information from PubMed to let you find data sets corresponding to a publication of interest.
Archived gene IDs
New sequencing technologies let labs construct better genome assemblies, bringing access to chromosome level assembly data even to relatively small research communities. We are excited to see this trend. Each genome update brings new evidence and potentially unlocks research into previously forbiddingly difficult biological questions.
At the same time, insights gathered in work published using previous assemblies should stay accessible to the community, so there is a need to connect different assemblies with each other. As of this release, WormBase ParaSite will keep track of previous identifier versions at gene level and display annotation history. Authors of a genome update do not always provide a mapping to previous version, so we developed a pipeline to match up identifiers between genome versions.
Overview of new functionality
For an overview of how this now works consider Smp_340760, a Schistosoma mansoni gene. The gene model was revised in the past, twice: it used to be called Smp_044010, but in “Schisto_7.1” version of the annotation that we published in WBPS11 the authors changed gene structure enough that they decided to assign it a new identifier, and in “Schisto_7.2” which we publish now the gene model was corrected slightly.
Searching by Smp_044010 now leads to a page explaining that the identifier was deprecated and redirecting to Smp_340760. Over there, the history is represented by a diagram:
The site also displays previous protein sequences of transcripts, to help you carry forward any conclusions based on the previous gene model – the less the sequence has changed, the more similar results will be for e.g. BLAST matches.
ID mapping pipeline
We used authors’ mappings between annotation versions for updates of Schistosoma mansoni and Hymenolepis microstoma. Everywhere else we used an automated mapping pipeline, adapted from Ensembl gene build.
The pipeline runs a sequence matching tool exonerate, scoring matches of exons between the two assemblies and propagating the scores onto the
transcript and gene level. The scores are then adjusted based on synteny – if a gene A is near gene B in the previous genome, A is mapped to A’ in the new genome, and there is a gene B’ near A’, the match of B to B’ is strengthened. Finally, best matches are iteratively taken out of the scoring, producing a list of pairs.
Results and benchmarking
We find the pipeline to be quite conservative even after we relaxed a few parameters around minimal match scores and similar values. Typically only between a third and two thirds of the genes in the updated genome have a related past identifier:
|Genome||previous genes total||previous version||mapped||new genes total||fraction mapped|
|Ancylostoma ceylanicum PRJNA72583||11783||WBPS11||7564||15892||0.476|
|Ascaris suum PRJNA62057||17974||WBPS9||9468||15260||0.620|
|Fasciola hepatica PRJEB25283||16806||WBPS10||7564||22676||0.334|
|Haemonchus contortus PRJEB506||19430||WBPS10||11439||21869||0.523|
|Meloidogyne incognita PRJEB8714||45351||WBPS10||11977||19212||0.623|
We also ran the automated pipeline on the S. mansoni WBPS10->WBPS11 update, comparing the results to a manual mapping obtained by annotators tracking individual identifiers. Our pipeline carried forward 5165 genes that authors considered to have none or minor changes, and 1347 genes with larger changes, onto an annotation with 10172 genes. The pipeline missed 2584 genes present somewhere in the manual mapping that were lost in the automatic one. It disagreed with the manual mapping in only 199 cases: some were genuinely wrong calls, and some are some were on par with manual mapping by being e.g. a mapping to a paralog gene.