Differential display reverse transcription PCR applied to male Mytilus edulis mussels with two distinct mitochondrial DNA types

Differential display reverse transcriptase PCR (DD-RT-PCR) was used to test for differences in gene expression in gonad tissue of 12 male blue mussels (Mytilus edulis) containing one of two distinct types of mitochondrial DNA. These two male mitotypes, referred to as the “standard” and “recently-masculinized” M-types, respectively, exhibit ∼16.5% uncorrected sequence divergence and ∼8.7% amino acid sequence divergence. Pairwise comparisons of the resulting banding patterns produced from nine separate DD-RT-PCR primer combinations were used to produce a distance matrix based on patterns of band sharing calculated using Jaccard's coefficient of similarity. Neighbor-joining analysis of this distance matrix resulted in clustering of the samples according to their mitotype. The next step in the analysis will be to determine if the bands that are differentially expressed in the two classes of samples reflect differential gene expression as a consequence of interactions between the nuclear and mitochondrial genomes or if the pattern observed is due to simple nuclear genetic differences between two diverging populations of mussels.