The mitochondrial cytochrome C oxidase subunit I gene (COI) is commonly used in environmental DNA (eDNA) metabarcoding studies, especially for assessing metazoan diversity. Yet, a great number of COI operational taxonomic units (OTUs) or/and amplicon sequence variants (ASVs) retrieved from such studies do not get a taxonomic assignment with a reference sequence. To assess and investigate such sequences, we have developed the Dark mAtteR iNvestigator (DARN) software tool. For this purpose, a reference COI-oriented phylogenetic tree was built from 1,593 consensus sequences covering all the three domains of life. DARN makes use of this phylogenetic tree to investigate COI pre-processed sequences of amplicon samples to provide both a tabular and a graphical overview of their phylogenetic assignments.
We demonstrate that a large proportion of non-target prokaryotic organisms, such as bacteria and archaea, are also amplified in eDNA samples and we suggest prokaryotic COI sequences to be included in the reference databases used for the taxonomy assignment to allow for further analyses of dark matter
Beyond learning the basics of the various methods used when studying fluxes, I was so glad that I was proved wrong about online events and whether the attendees can actually interact one another.
A big, big “thank you” to all members of the organizing committee and a promise for an in-person meeting sometime soon! 🦠 🧬
We are still in the start, but GSoC many thanks for supporting our efforts for random sampling over the flux space of microbial communities metabolic networks!
A revised version of the darn software tool is now available. Dark mAtteR iNvestigator (DARN) uses a COI reference tree covering all domains of life (eukaryotes, bacteria, archaea) to assign your sequences to the 3 domains of life.
Its purpose is not to provide you with certain taxonomic assignment but to give an overview of the species present.
PFam oriented bacterial sequences have been added in the initial sequences dataset and allowing us to cover 371 families plus 60 taxonomic groups of higher level not assigned in family.
To get this latest version, you just need to install docker and run
docker pull hariszaf/darn:latest
Have fun discovering more and more bacteria on your COI amplicon data! 🥳
Our manuscript on the history, the usage and the scnientific impact of the IMBBC HPC facility over the last 10 years was just published on the GigaScienece journal.
High-performance computing (HPC) systems have become indispensable for modern marine research, providing support to an increasing number and diversity of users. Pairing with the impetus offered by high-throughput methods to key areas such as non-model organism studies, their operation continuously evolves to meet the corresponding computational challenges. Here, we present a Tier 2 (regional) HPC facility, operating for over a decade at the Institute of Marine Biology, Biotechnology, and Aquaculture of the Hellenic Centre for Marine Research in Greece. Strategic choices made in design and upgrades aimed to strike a balance between depth (the need for a few high-memory nodes) and breadth (a number of slimmer nodes), as dictated by the idiosyncrasy of the supported research. Qualitative computational requirement analysis of the latter revealed the diversity of marine fields, methods, and approaches adopted to translate data into knowledge. In addition, hardware and software architectures, usage statistics, policy, and user management aspects of the facility are presented. Drawing upon the last decade’s experience from the different levels of operation of the Institute of Marine Biology, Biotechnology, and Aquaculture HPC facility, a number of lessons are presented; these have contributed to the facility’s future directions in light of emerging distribution technologies (e.g., containers) and Research Infrastructure evolution. In combination with detailed knowledge of the facility usage and its upcoming upgrade, future collaborations in marine research and beyond are envisioned.
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