Sujai Kumar | Search bioRxiv

bioRxiv2016

Lepbase: the Lepidopteran genome database

As the generation and use of genomic datasets is becoming increasingly common in all areas of biology, the need for resources to collate, analyse and present data from independent (Tier 1) species-level genome projects into well supported clade-oriented (Tier 2) databases and provide a mechanism for these data to be propagated to pan-taxonomic (Tier 3) databases is becoming more pressing. Lepbase is a Tier 2 genomic resource for the Lepidoptera, supporting a research community using genomic approaches to understand evolution, speciation, olfaction, behaviour and pesticide resistance in a wide range of target species. Lepbase offers a core set of tools to make genomic data widely accessible including an Ensembl genome browser, text and sequence homology searches and bulk downloads of consistently presented and formatted datasets. As a part of the taxonomic community that we serve, we are working directly with Lepidoptera researchers to prioritise analyses and add tools that will be of most value to current research questions.

Bioinformatics↗

bioRxiv2015

No evidence for extensive horizontal gene transfer in the genome of the tardigrade Hypsibius dujardini

Tardigrades are meiofaunal ecdysozoans that are key to understanding the origins of Arthropoda. Many species of Tardigrada can survive extreme conditions through cryptobiosis. In a recent paper (Boothby TC et al (2015) Evidence for extensive horizontal gene transfer from the draft genome of a tardigrade. Proc Natl Acad Sci USA 112:15976-15981) the authors concluded that the tardigrade Hypsibius dujardini had an unprecedented proportion (17%) of genes originating through functional horizontal gene transfer (fHGT), and speculated that fHGT was likely formative in the evolution of cryptobiosis. We independently sequenced the genome of H. dujardini. As expected from whole-organism DNA sampling, our raw data contained reads from non-target genomes. Filtering using metagenomics approaches generated a draft H. dujardini genome assembly of 135 Mb with superior assembly metrics to the previously published assembly. Additional microbial contamination likely remains. We found no support for extensive fHGT. Among 23,021 gene predictions we identified 0.2% strong candidates for fHGT from bacteria, and 0.2% strong candidates for fHGT from non-metazoan eukaryotes. Cross-comparison of assemblies showed that the overwhelming majority of HGT candidates in the Boothby et al. genome derived from contaminants. We conclude that fHGT into H. dujardini accounts for at most 1-2% of genes and that the proposal that one sixth of tardigrade genes originate from functional HGT events is an artefact of undetected contamination.

Genomics↗