Title

Variation in expression of duplicated insulin-like receptor genes in Daphnia pulex

Presenter Information

Ian Wooller

Document Type

Oral Presentation

Location

SURC Ballroom A

Start Date

16-5-2013

End Date

16-5-2013

Abstract

Publication of the Daphnia pulex genome in 2011 identified D. pulex as the arthropod with the highest homology to humans at the genetic level. This conservation of genes opens up the possibility of using D. pulex as a model organism for biomedical research. For example, D. pulex possesses at least 15 genes with high homology to human genes involved in the insulin signalling pathway (ISP). In addition, both Daphnia and vertebrate lineages have experienced duplication of insulin-like receptor genes in their evolutionary history. In this study, we assessed patterns of expression of the insulin-like receptors under calorie restricted conditions in five natural populations of D. pulex in Kittitas county. Eight clonal lines from each population were cultured in laboratory conditions under two treatments: fed ad libitum and calorie restricted. Expression levels of the four insulin-like receptor genes and three additional genes in the ISP were measured using quantitative PCR. Calorie restriction had a significant effect on expression levels of all genes, but the magnitude and direction of effects differed between populations. In addition, the direction of effect differed between different insulin-like receptors, suggesting neofunctionalization of at least one copy of this gene. To our knowledge, this is the first study to show variation in direction of expression between duplicated insulin-like receptor genes in D. pulex. It is also the first to show population-level variation in expression of genes in the ISP in Daphnia. Future research will include the effect of other environmental factors on expression of these genes.

Faculty Mentor(s)

Alison Scoville, Joseph Lorenz

Additional Mentoring Department

Biological Sciences

Additional Mentoring Department

Anthropology

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May 16th, 1:50 PM May 16th, 2:10 PM

Variation in expression of duplicated insulin-like receptor genes in Daphnia pulex

SURC Ballroom A

Publication of the Daphnia pulex genome in 2011 identified D. pulex as the arthropod with the highest homology to humans at the genetic level. This conservation of genes opens up the possibility of using D. pulex as a model organism for biomedical research. For example, D. pulex possesses at least 15 genes with high homology to human genes involved in the insulin signalling pathway (ISP). In addition, both Daphnia and vertebrate lineages have experienced duplication of insulin-like receptor genes in their evolutionary history. In this study, we assessed patterns of expression of the insulin-like receptors under calorie restricted conditions in five natural populations of D. pulex in Kittitas county. Eight clonal lines from each population were cultured in laboratory conditions under two treatments: fed ad libitum and calorie restricted. Expression levels of the four insulin-like receptor genes and three additional genes in the ISP were measured using quantitative PCR. Calorie restriction had a significant effect on expression levels of all genes, but the magnitude and direction of effects differed between populations. In addition, the direction of effect differed between different insulin-like receptors, suggesting neofunctionalization of at least one copy of this gene. To our knowledge, this is the first study to show variation in direction of expression between duplicated insulin-like receptor genes in D. pulex. It is also the first to show population-level variation in expression of genes in the ISP in Daphnia. Future research will include the effect of other environmental factors on expression of these genes.