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Seasonal and sex-dependent gene expression in emu (Dromaius novaehollandiae) fat tissues Wright, Kristina


The emu (Dromaius novaehollandiae) is a bird that has been farmed for its oil, rendered from fat, for uses in therapeutics and cosmetics. Emu oil is valued for its anti-inflammatory and antioxidant properties, which promote wound healing. In spring and summer, adult emus start to gain fat and expend the energy from their fat stores during breeding in winter to sustain themselves when food is scarce. Since emus go through an annual cycle of fat gain and loss, understanding the genes affecting fat metabolism and deposition is crucial to improve fat production in emu farms. Samples were taken from back and abdominal fat tissues of the same four male and four female emus in April, June, and November for RNA-sequencing. In November, the emus’ body and fat pad weights were recorded. Seasonal and sex-dependent differentially expressed (DE) genes were analyzed and genes involved in fat metabolism were identified. A total of 100 DE genes (47 seasonally in males; 34 seasonally in females; 19 between sexes) were found. Seasonally DE genes generating significant difference between the sexes in gene ontology terms as well as supporting studies suggested integrin beta chain-2 (ITGB2) influences fat changes. Six seasonally DE genes functioned in more than two enriched pathways (two female: angiopoietin-like 4 (ANGPTL4) and lipoprotein lipase (LPL); four male: lumican (LUM), osteoglycin (OGN), aldolase B (ALDOB), and solute carrier family 37 member 2 (SLC37A2)). Two sexually DE genes, follicle stimulating hormone receptor (FSHR) and perilipin 2 (PLIN2), had functional investigations supporting their influence on fat gain and loss. The results suggested these nine genes (ITGB2, ANGPTL4, LPL, LUM, OGN, ALDOB, SLC37A2, FSHR, PLIN2) functionally influence fat metabolism and deposition in emus. This study lays foundation for further downstream studies to improve emu fat production through selective breeding using single nucleotide polymorphism markers.

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