The University of Winnipeg’s Dr. Sara Good is part of a team of researchers whose recent findings have potential to play a pivotal role in the future of Great Lakes fisheries by assisting in the control of sea lamprey populations.
Results published in Nature Communications Biology as part of the recent paper “Pervasive male-biased expression throughout the germline-specific regions of the sea lamprey genome supports key roles in sex differentiation and spermatogenesis” suggest there has been significant progress made in uncovering the processes of sex differentiation, testicular development, and possibly sex determination. A UWinnipeg Biology professor, Good is the paper’s senior author and completed the work alongside Dr. Margaret Docker, Dr. Phil Grayson, and first author Tamanna Yasmin, Good’s co-supervised PhD student.
“There’s been a real growth in our understanding of the diversity of the mechanisms that vertebrates use to determine sex,” said Good. “That has exploded because of all the new molecular methods over the last 10 years. We don’t know the mechanism of sex determination in lamprey yet, but this paper gave clear evidence that we’re on the trail of finding what that mechanism could be.”
We don’t know the mechanism of sex determination in lamprey yet, but this paper gave clear evidence that we’re on the trail of finding what that mechanism could be.
Dr. Sara Good
The original aim of the research was to find the genes associated with gonad development in sea lampreys, the oldest living lineage of vertebrates on the planet. While some species, such as humans, have sex determined primarily by genetics, a combination of genetics and environment plays a role in sex determination in many species of fish. In the case of sea lampreys, the basis of sex determination has remained largely unknown.
But discovering the cause is of particular importance to those in the Great Lakes region as it could present opportunities for genetic control options that could benefit freshwater fisheries.
First recorded in Lake Ontario in the 1830s, sea lamprey – a parasitic fish that sucks the blood from its prey – populations exploded and expanded to the four remaining Great Lakes by the 1940s as a result of improvements to the Welland Canal system. This led to the eventual collapse of many Great Lakes freshwater fisheries throughout the 1940s and 1950s. The once-thriving Great Lakes fisheries, which produced an estimated 15 million pounds of lake trout prior to the sea lamprey proliferation, were producing only 300,000 pounds per year, according to the Great Lakes Fishery Commission (GLFC), which funded the research undertaken by Good, Docker, Grayson, and Yasmin.
Through the use of lampricides and barriers prohibiting access to spawning habitats, the GLFC has been able to suppress sea lamprey populations by up to 95 percent. However, as the more than half-century-old barriers lapse into a state of disrepair, there is increased interest in developing new ways to reduce the population, including through genetic control options. This could include biasing the sex ratio or creating sterile males and females.
Good said the paper’s findings, further explained in a related blog post, provide an “avenue for pursuing this work further to see if we can determine the key genes involved in sex determination or male and female fecundity and then assess if modifying these genes could allow for genetic control options for sea lamprey in the upper Great Lakes.”
Currently applying for more funding to dig deeper into the research, Good wants next to sequence the genome of the female gonad and continue the pursuit of finding the genes which play a role in sex determination. She believes it can be accomplished within the next five years and added that transgenic experimentation through the use of gene editing to examine the effect of modifying specific genes is possible within the next decade.
“The methods to do targeted gene editing (i.e. CRISPR-Cas9) have been successfully used in lamprey by other researchers – ultimately, I would like to broaden my collaborations to include people that use those methods so that we can test the effect of modifying the genes we think influence sex determination or fecundity” said Good. “Then deploying it into nature would be a whole different kettle of fish.”