Summarizing the key genome annotation resources in Bioconductor

Executive summary

Organism-oriented annotation

For biological annotation, generally sequence or gene based, there are three key types of package

• Reference sequence packages: BSgenome.[Organism].[Curator].[BuildID]
• Gene model database packages: TxDb.[Organism].[Curator].[BuildID].[Catalog]
• Annotation map package: org.[Organism2let].[Institution].db

wherever brackets are used, you must substitute an appropriate token. You can survey all annotation packages at the annotation page.

Packages Homo.sapiens, Mus.musculus and Rattus.norvegicus are specialized integrative annotation resources with an evolving interface. We have illustrated their use in lectures and labs.

Systems biology oriented annotation

Packages GO.db, KEGG.db, KEGGREST, and reactome.db are primarily intended as organism-independent resources organizing genes into groups. However, there are organism-specific mappings between gene-oriented annotation and these resources, that involve specific abbreviations and symbol conventions. These are described when these packages are used.

Names for organisms and their abbreviations

The standard Linnaean taxonomy is used very generally. So you need to know that

• Human = Homo sapiens
• Mouse = Mus musculus
• Rat = Rattus norvegicus
• Yeast = Saccharomyces cerevisiae
• Zebrafish = Danio rerio
• Cow = Bos taurus

and so on. We use two sorts of abbreviations. For Biostrings-based packages, the contraction of first and second names is used

• Human = Hsapiens
• Mouse = Mmusculus
• Rat = Rnorvegicus
• Yeast = Scerevisiae …

For NCBI-based annotation maps, we contract further

• Human = Hs
• Mouse = Mm
• Rat = Rn
• Yeast = Sc …

Genomic sequence

These packages have four-component names that specify the reference build used

• Human = BSgenome.Hsapiens.UCSC.hg19
• Mouse = BSgenome.Mmusculus.UCSC.mm10
• Rat = BSgenome.Rnorvegicus.UCSC.rn5
• Yeast = BSgenome.Scerevisiae.UCSC.sacCer3

Gene models

These packages have five-component names that specify the reference build used and the gene catalog

• Human = TxDb.Hsapiens.UCSC.hg19.knownGene
• Mouse = TxDb.Mmusculus.UCSC.mm10.knownGene
• Rat = TxDb.Rnorvegicus.UCSC.rn5.knownGene
• Yeast = TxDb.Scerevisiae.UCSC.sacCer3.sgdGene

Annotation maps

These packages have four component names, with two components fixed. The variable components indicate organism and curating institution.

• Human = org.Hs.eg.db
• Mouse = org.Mm.eg.db
• Rat = org.Rn.eg.db
• Yeast = org.Sc.sgd.db

Additional options

There are often alternative curating institutions available such as Ensembl.