Trends in molluscan gene sequence similarity: An observation from genes expressed within the hypobranchial gland of Dicathais orbita (Gmelin, 1791) (Neogastropoda: Muricidae)

摘要

This study investigates the phylogenetic distribution of homol-ogy to Dicathais orbita hypobranchial gland genes based ontBLASTx pairwise sequence alignments from the Genbankdatabase. Suppressive subtractive hybridization was used toobtain 417 non-redundant genes that were up-regulated oruniquely expressed in the hypobranchial gland relative to man-tle tissue. Of these, 133 sequences revealed matches to thedatabase with the remaining 68% of genes appearing as appar-ently novel sequences. Homologous sequence matches wereobserved for a wide range of evolutionarily divergent taxa,encompassing animals, protozoans, plants, fungi, bacteria, andviruses. The highest frequency of homology was found towardschordate sequences, followed by the Mollusca, which high-lights the current bias in availability of vertebrate versus inver-tebrate sequences in the database. An unexpectedly highproportion of matches were also found toward the Ciliophora,indicating a possible symbiotic relationship, as well as theAscomycota and Streptophyta, which share the ability to bio-synthesize indole derivatives with Muricidae such as Dicathaisorbita. Overall, these results reveal the usefulness of undertak-ing sequence comparisons in gene expression and highlight thecurrent paucity of knowledge of molluscan genomes.