Tribolium castaneum with longer duration of tonic immobility have more variations corresponding to the human Parkinson's disease genomic region.

Parkinson’s disease (PD) is a common neurodegenerative syndrome characterized by the loss of dopaminergic neurons and is also a progressive neurodegenerative disorder that is characterized by dopamine deficiency. We established strains artificially selected for longer and shorter durations of tonic immobility, an antipredator behavior that has received much attention recently, in the red flour beetle, Tribolium castaneum, a model insect species for molecular analyses different from Drosophila melanogaster. Previous studies have shown that the long strains (L-strain) have significantly lower levels of dopamine expression in the brain than the short strains (S-strain) and that they have an abnormal pattern of locomotor activity. Furthermore, previous studies have shown that administering dopamine to L-strain beetles reduces the duration of tonic immobility. Transcriptome analysis of brain and thorax of the L- and S-strains also showed differences in mRNA expression of genes involved in dopamine synthesis and tyrosine metabolism. These results indicate that the phenotype and molecular basis of the L-strain are similar to those of Parkinson’s syndrome symptoms. In order to establish a link between T. castaneum and PD, we compared the DNA sequences of the L- and S-strains to human genes affecting dopaminergic pathways. The DNA comparison revealed many mutated regions in these genes in the L-strain. We discuss the relationship between dopaminergic pathway genes and PD-like phenotypes across humans, Drosophila, and the red flour beetle.