S. Garcia-Vallve, E. Guzman, MA. Montero and A. Romeu. 2003. HGT-DB: a database of putative horizontally transferred genes in prokaryotic complete genomes. Nucleic Acids Research, 31:187-189.

The HGT-DB is a genomic database that includes statistical parameters such as G+C content, codon and amino-acid usage, as well as information about which genes deviate in these parameters for prokaryotic complete genomes. Under the hypothesis that genes from distantly related species have different nucleotide compositions, these deviated genes may have been acquired by horizontal gene transfer. The current version of the database includes the analysis of 94 bacterial and archaeal complete genomes, including multiple chromosomes and strains, when available. Other complete genomes will be added progressively.

Puigbo P, Romeu A and Garcia-Vallve S. 2008. HEG-DB: a database of predicted highly expressed genes in prokaryotic complete genomes under translational selection.Nucleic Acids Research, 36:D524-D527.

The HEG-DB is a genomic database that includes the prediction of which genes are highly expressed in prokaryotic complete genomes under strong translational selection. The current version of the database contains general features for almost 200 genomes under translational selection, including the correspondence analysis of the relative synonymous codon usage for all genes, and the analysis of their highly expressed genes. For each genome, the database contains functional and positional information about the predicted group of highly expressed genes. This information can also be accessed using a search engine. Among other statistical parameters, the database also provides the Codon Adaptation Index for all of the genes using the codon usage of the highly expressed genes as a reference set. The "Pathway Tools Omics Viewer" from the BioCyc database enables the metabolic capabilities of each genome to be explored, particularly those related to the group of highly expressed genes.