Posts Tagged ‘dfam’

Dfam 3.5 release

October 11, 2021

We are pleased to announce the the Dfam 3.5 release, which includes both new annotation data (available for download) and additional TE (transposable element) models and species.

TE annotation data

As part of this release, we have added annotation data for the curated TE entries for all of the extant species as part of the Zoonomia project (Figure 1). These data were curated by the combined work of David Ray’s lab at Texas Tech University (TTU) as well as the Smit group at the Institute for Systems Biology (ISB), and include young, lineage-specific TE models.

Figure 1: Example of the genomic annotation for a Dfam TE model.

TE models

271 Lineage-specific, curated LTR TE models for the reconstructed ancestor of New World monkeys as part of the Zoonomia project have also been added.Additional uncurated entries (DR records) have also been added for the duckweed (607 models) and Atlantic cod (2751 models) as part of TE families submitted to Dfam via the website interface. The next Dfam release will include additional submitted datasets. With the addition of these new families, Dfam now houses 285,542 TE models across 595 species (Figure 2; Figure 3). We look forward to the continued growth of Dfam!

Figure 2: Dfam model growth. Numbers above each bar indicate the number of total models in Dfam at the time of the indicated release.
Figure 3: Dfam species growth. Numbers above each bar indicates the number of total species in Dfam at the time of the indicated release.

Dfam 3.4 Release

July 24, 2021

The Dfam Consortium is proud to announce the release of Dfam 3.4. This update includes over 8,200 curated transposable element (TE) families found in 240 mammalian genomes. The models therein have been carefully developed by David Ray’s lab at Texas Tech University (TTU) and further refined by Arian Smit. This is part of an ongoing effort to generate a comprehensive mammalian TE library using multi-species alignments and ancestral sequence reconstructions generated by the Zoonomia project (https://zoonomiaproject.org).

In addition to releasing the curated TE families, full genome annotations are provided for 21 Old World monkeys (Figure 1; Figure 2).

Figure 1: A portion of the available genomes aligned as part of the Zoonomia project, focused on the Primate Order.

Discovery of young, species-specific TEs

As a large portion of a mammalian genome, TEs serve as a source for genomic variation and innovation, including (but certainly not limited to) genomic rearrangement via movement and non-homologous recombination and providing novel transcription factor binding sites. David Ray’s lab has taken the first large-scale effort into examining the TE content of the extant genomes as part of the Zoonomia project in order to determine the TE type and location and subsequently the impact they might have on the evolution of each lineage of mammals. 

Methods

A total of 248 final genome assemblies of placental mammals were initially presented for analysis, most coming from the Zoonomia dataset. Low quality assemblies and previously analyzed genomes were excluded from analyses. To avoid wasted effort on re-curation of previously described TEs, manual curation efforts were focused towards identifying newer putative TEs that underwent relatively recent accumulation, with the main assumption being that many older TEs will be widely shared among large groups of placental mammals and that previous annotation efforts have thoroughly described these older elements in detail.

To classify younger TEs, the filtered dataset was narrowed to elements that have undergone transposition in the recent past, i.e. TEs that have insertion sequences with Kimura 2 parameter (K2P) distances less than 4.4% (approximately ~20my or less since insertion, based on a general mammalian neutral mutation rate of 2.2×10-9). This approach yielded mostly lineage specific TEs, many of which were yet to be previously described.

For each iteration of manual TE curation, new consensus sequences were generated from the 10-50 top BLAST hits, and aligning these sequences via MUSCLE and estimating a consensus sequence with EMBOSS.

To reduce library redundancy, the potential TE consensus sequences were combined with those of known TEs from previous work as well as all known vertebrate TEs from Repbase. The program CD-HIT-EST was used to identify duplicate TEs among our combined TE library according to the 80-80-80 rule of Wicker et al.

To confirm the TE type, each sequence in the library was subjected to a custom pipeline which used: blastx to confirm the presence of known ORFs in autonomous elements, RepBase to identify known elements, and TEclass to predict the TE type. In addition, structural criteria was also utilized for categorizing TEs: DNA transposons, elements with visible terminal inverted repeats; rolling circle transposons were required to have identifiable ACTAG at one end; putative SINEs were inspected for a repetitive tail as well as A and B boxes; LTR retrotransposons were required to have recognizable hallmarks, such as: TG, TGT, or TGTT at their 5’ and the inverse at the 3’ ends.   

Zoonomia Project

Figure 2: Summary of the Zoonomia project

The Zoonomia project is an effort to understand the mammalian tree of life at a deeper level. This massive undertaking is the collaboration of 27 laboratories. Although far from a complete list, some current projects derived from the Zoonomia datasets include: studying mammalian speech development, regulatory element analyses, chromosome evolution and the evolution of microRNA genes.

Future Work

Future efforts will continue to analyze and catalog lineage-specific TEs in deeper branches of the 240-way genome alignment via the reconstructed genomes at each node of the phylogenetic tree as part of the alignment and expand the full genome annotations available on Dfam.

Curation with Dfam: new data and platform updates

March 17, 2020

DNA transposon termini signatures

The Dfam consortium is excited to announce the generation and release of terminal repeat sequence signatures for class II DNA transposable elements. The termini of class II elements are crucial for movement, and as such, can be used to classify de novo DNA transposable element families in new genomic sequences (Figure 1).

Figure 1. Major subgroups of class II DNA transposons.

The LOGOs of the termini can be viewed on the “Classifications” tab on the Dfam website and are organized by class II subclasses (e.g., Crypton, Helitron, TIR, etc.) (Figure 2). This allows for easy visualization of the base conservation at each position in the terminal sequences and comparisons between the 5’ and 3’ termini (Figure 2). In addition, the termini profiles are available for download as a .HMM file.

Figure 2. Termini signature visualization on the Dfam website (www.dfam.org) sample. Base conservation can be seen via the LOGOs of the 5’, 3’ and combined edge (termini) HMMs. The movement type can be seen preceding DNA transposons that move via a common mechanism (e.g. “Circular dsDNA intermediate). The number of families used to generate the LOGOs are indicated, as well as the subclass named (e.g. “Crypton_A”). Additional notes on the termini, when relevant, are also available.

Community data submissions

We have taken the first small step towards a community-driven data curation platform by developing a new data submission system.  At the start this will facilitate the process of uploading data to the site for processing by the curators. As we move forward, further aspects of the curation process will be made available to the community.  Upon creating an account and logging in, users can submit files to Dfam using our web-based upload page. Here you will also find information about submission requirements and how different levels of library quality are handled in Dfam.

Moving to xfam.org

May 1, 2014

Back in November 2012 we announced that the Xfam team in the UK was moving from the Wellcome Trust Sanger Institute to the European Bioinformatics Institute (EMBL-EBI), just next door on the Wellcome Trust Genome Campus. On Tuesday we completed that move by switching off the Pfam and Rfam websites inside Sanger and redirecting all traffic to our shiny new home at xfam.org. You can now find the Pfam and Rfam websites at pfam.xfam.org and rfam.xfam.org respectively. Read the rest of this entry »

TreeFam 9 is now available!

May 3, 2013

We are happy to announce that TreeFam 9 is online and you can find it under http://www.treefam.org.

TreeFam 9 now has 109 species (vs. 79 in TreeFam 8) and is based on data from Ensembl v69, Ensembl Genomes v16, Wormbase and JGI.

This release marks an important step for TreeFam as it is the first release build since TreeFam has been resurrected.
Here is a list of the most important changes in TreeFam 9:

  • New website layout (adopting the Pfam/Rfam/Dfam layout)
  • Infrastructure move of web servers and databases to the EBI
  • Sequence search against the library of TreeFam family profiles
  • new tree visualisations in pure javascript using D3, e.g. see the BRCA2 gene tree here.
  • Pairwise homology download

We hope you find all the information you are looking for. If you don’t, please let us know so that we can include the information you want. The old website will remain online here.

If you have questions, suggestions or find bugs, don’t hesitate to contact us through our new forum here.

Happy treefamming,

the TreeFam team
(Fabian, Mateus)

Dfam paper is an NAR “featured article”; RepeatMasker4 is out

January 12, 2013

We are pleased to announce that the Dfam paper (“Dfam: a database of repetitive DNA based on profile hidden Markov models“) is now available in the 2013 NAR Database issue, and has been selected as a “featured article” (meaning the NAR editorial board thinks it is among “the top 5% of papers in terms of originality, significance and scientific excellence”).

In other exciting news, two members of the Dfam consortium, Arian Smit and Robert Hubley (Institute for Systems Biology, Seattle), just released RepeatMasker 4.0. This is a major update that, among other important improvements, adds support for searching with Dfam and nhmmer. Go get yourself a copy at http://www.repeatmasker.org/

Posted by Travis

Dfam 1.1 released

November 15, 2012

We are pleased to announce that we’ve released Dfam 1.1. This version represents a few important changes from 1.0, including updated hit results, a new tab for each entry page showing relationships to other entries, and improved handling of redundant profile hits.

Read the rest of this entry »

Dfam: A database of repetitive DNA elements

September 6, 2012

We are pleased to introduce Dfam 1.0, a database of profile HMMs for repetitive DNA elements. Repetitive DNA, especially the remnants of transposable elements, makes up a large fraction of many genomes, especially eukaryotic. Accurate annotation of these TEs both simplifies downstream genomic analysis and enables research into their fascinating biology and impact on the genome.

Read the rest of this entry »