Jullien Flynn, Département de biologie
I am an assistant professor in the Department of Biology at Université Laval. I am also affiliated with the Institute of Integrative Biology and Systems (IBIS). My work is in the domains of evolution, genetics, genomics, and development. At IBIS, I am launching a research program using evo-devo approaches to investigate the functional significance of repetitive DNA, using fruit flies as a model organism. I am interested in understanding the variation in repetitive DNA content, and particularly how this variation impacts cellular function. My work is especially relevant for reproductive biology.
Satellite DNA is long noncoding tandem arrays of repeated sequences composing 1-50% of eukaryotic genomes. With its large abundance and repetitive structure, satellite DNA is expected to challenge cellular function by being prone to instability, being a burden, or even interfering with the regulation of essential genes. At the same time, with its ability to evolve rapidly, it might co-opt functions that become important for development, such as in reproduction which is a process that faces constant selective pressures.
Projects in my lab investigate satellite DNA’s roles from both sides: the challenges of having it in large amounts in the genome, and its potential benefits in specific contexts. One project will investigate how satellite DNA instability can contribute to chromosome segregation errors, which are drivers of multiple human health problems. Second, using closely related species that have diverged rapidly in the amount of satellite DNA on one chromosome, we will ask whether changing the satellite DNA abundance impacts specific developmental processes. Finally, we will investigate the functional and evolutionary significance of satellite DNA expression the germline. Overall, we hope to understand why satellite DNA varies in sequence and abundance among different species, and how organisms adapt to the intrinsic challenge of the bulk repetitive DNA. In addition to the model organism Drosophila melanogaster, my research program centres D. virilis, within which I have discovered three distinct systems suited to my research questions that are inaccessible in D. melanogaster. The main methodologies my lab uses are: visualising chromosomes and gene expression within tissues with DNA and RNA FISH, and bioinformatics (especially genomic intervals, copy number, and RNA-seq analyses).