Carausius morosus (Phasmatodea) Homologues of Human Genes with Elevated Expression in the Colon

Background: Preliminary testing of novel drugs for colorectal conditions must be performed on animal models, with invertebratemodels desirable for practical reasons. The insect excretory organs, the Malpighian tubules, have been cited as models for humanrenal disease research because they differentially express several genes homologous to those differentially expressed in humankidneys. Their role in excretion and homeostasis suggests that they could be models for human colorectal disease. The insect Carausiusmorosus (Phasmatodea) has been a model organism for decades. Regarding its potential use as a colorectal disease model,it has an advantage over other insects in that excretion in Phasmatodea is split between two organs: Malpighian tubules and thePhasmatodea-specific “appendices of the midgut”.Objectives: To find homologues of human colon genes expressed in the excretory tissues of C. morosus for potential use in drugtesting and other experiments requiring an animal model.Methods: Pre-existing transcriptomics data for the excretory system of the C. morosus were examined to find genes homologous tothose known to have elevated expression in the human colon. This was done with the goal of possibly determining the excretorytissues in which they are differentially expressed.Results: Exactly sixty transcripts from the excretory system transcriptome of C. morosus showed high sequence homology withhuman colon-specific genes, with a minimum e-value of 1e-50. Examples include solute carriers, myosin, bestrophin, carbonic anhydrase,and nitric oxide synthase. Several genes were identified with prognostic value for renal, pancreatic, endometrial, liver, skin,and urothelial cancers.Conclusions: C. morosus can be used as model insect for human medical research applications, including colorectal drug testing.