Honours Research: Sequencing Mitochondrial Genomes with Mark O’Reilly

By Theodore Giesen

Theodore Giesen is a summer co-op student in the Research Office, and an undergraduate English student here at Acadia. Over the summer, Theodore has been interviewing Acadia students and faculty about their recent research activities and writing up his findings in profiles for the website. We'll be sharing profiles like this one in the coming weeks - check back for more stories of research at Acadia.

Honours student Mark O’Reilly (Biology) has been given a rare opportunity to study the natural phenomenon known as doubly uniparental inheritance (DUI).

To understand doubly uniparental inheritance, one must first understand what mitochondrial DNA is. The mitochondrion, an organelle responsible for the generation of energy for the body, possesses its own DNA molecule that is separate from the DNA found in the nucleus of each cell (chromosomal DNA). The inheritance of mitochondrial DNA is distinct from the inheritance of chromosomal DNA. An almost universal trait of mitochondrial DNA is that it is maternally inherited (offspring only receive mitochondrial DNA from their mothers). Doubly uniparental inheritance (DUI) is a mode of mitochondrial DNA inheritance found in some species of bivalves and is an exception to strict maternal inheritance. In DUI, mitochondrial DNA passed onto the offspring can be from mothers to female and male offspring as well as from fathers to male offspring (male mitochondrial DNA located in germ line cells). The result is two distinct, gender-associated lineages of mitochondrial DNA (male and female mitochondrial DNA molecules are different). O’Reilly is studying DUI in Geukensia demissa, a species of mussels commonly referred to as the ribbed mussel.

The purpose of O’Reilly’s research on this species is to determine the sequence of nucleotides in the male mitochondrial genome and then potentially re-sequence a region of uncertainty in the female mitochondrial genome to compare the two. These sequences can be used as references in other research projects on Geukensia demissa and other species exhibiting doubly uniparental inheritance in the future.

Having been exposed to microbiology, cell biology, and evolutionary biology through undergraduate classes, O’Reilly came into his research project eager to expand his knowledge on the underlying processes that operate in living organisms. Paired with supervisor Dr. Don Stewart (Biology), they continue work done by other Honours students done in the past.

When asked about the relevance of his research, O’Reilly admitted it was not headline news, though defended its importance in the scientific community. “I think my research is a little more niche and that it is not easy for most people to grasp” said O’Reilly. O’Reilly emphasizes the uniqueness of the phenomenon of DUI and how projects like his help expand our understanding of the evolutionary origins and distribution of DUI.

Using a combination of molecular techniques such as DNA extraction methods and long-range polymerase chain reaction, O’Reilly amplifies mitochondrial DNA samples to send away for sequencing and analyzes the sequence data once completed. Once the complete male mitochondrial genome has been sequenced, the results may be turned into a publication that could assist in future doubly uniparental inheritance research.

This ongoing research has been passed through the hands of several Honours students, and O’Reilly would like to see it completed. Many months of work in the lab lay ahead, but O’Reilly doesn’t mind: “For one, the research is incredibly interesting, and two, it’s a really positive and relaxed work environment. It isn’t hard to be self-motivated when everyone around you is working hard and happy to be there.” 

Look forward to seeing all Honours theses in the Library or available online once completed.

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