[Seminar] Comparative analysis of the cobia (Rachycentron canadum) genome identifies ephx1 as a novel putative master sex-determining gene in teleosts


Thursday, September 15, 2022 - 14:00 to 15:00


OIST Seminar room C210


Seminar: Comparative analysis of the cobia (Rachycentron canadum) genome identifies ephx1 as a novel putative master sex-determining gene in teleosts  



Dr Xueyan Shen, Senior Lecturer Aquaculture Institute, James Cook University Singapore.


Cobia (Rachycentron canadum) is the only member of the Rachycentridae family and exhibits considerable sexual dimorphism in growth rate. Sex determination in teleosts has been a long-standing basic biological question. The molecular mechanisms of sex determination/differentiation in cobia species is completely unknown.
We reported high-quality, chromosome-level genome sequences of male cobia with a genome assembly size of 586.51 Mb (contig/scaffold N50: 86.0 kb/24.3 Mb) and female cobia, 583.88 Mb (79.9 kb/22.5 Mb).
Syntheny inference among perciform genomes revealed that cobia and the remora Echeneis naucrates were sister groups.
Whole genome resequencing of 31 males and 60 females, genome-wide association analysis and sequencing depth analysis identified three short male-specific regions within a 10.7 kb continuous genomic region on male chromosome 18, which hinted at an undifferentiated sex chromosome system with a XX/XY mode of sex determination in cobia.

The only gene within the male-specific regions, cobia epoxide hydrolase 1 (Cephx1Y), which codes for a xenobiotic metabolizing enzyme that is functionally associated with the cytochrome (CYP) P450 family, showed testis-specific PCR amplification and gene expression, is identified here as a novel putative master gene driving sex determination in cobia.

The comprehensive genomic survey presented here establishes solid evidence of a novel genetic factor involved in sex determination in a unique representative of teleost fish and is a valuable resource for future genome-scale studies in cobia.


Dr. Xueyan Shen obtained her M.Sc in Aquaculture and Ph.D. in Biochemistry and Molecular Biology from the Ocean University of China in 2004 and 2007, respectively. After that, she started her Postdoctoral work on maintenance of genomic resources for the National BioResource Project Medak in NIBB (Okazaki, Japan). From 2010, she worked in the Temasek Life Sciences Laboratory (TLL), Singapore, where as a Research Fellow, she led several research teams towards increasing Singapore’s food fish supply through application of aquaculture genomics R&D. She has now joined James Cook University in Singapore where she will continue to apply her state-of-the-art teaching and genetic research approaches to help Singapore as well as other Asia counties achieve their aquaculture related food security strategy.

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Meeting ID: 942 1416 2472  Pass code: 277746


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