Zoological Studies

Vol. 62, 2023

(update: 2023.1.1)

Identification of Sexually Dimorphic Genes in Pectoral Fin as Molecular Markers for Assessing the Sex of Japanese Silver Eels (Anguilla japonica)

Hsiang-Yi Hsu1, Chia-Hsien Chuang2, I-Hsuan Lu2, Chung-Yen Lin2, and Yu-San Han1,*

1Institute of Fisheries Science, College of Life Science, National Taiwan University, 1, Sec. 4, Roosevelt Rd., Taipei 10617, Taiwan. *Correspondence: E-mail: yshan@ntu.edu.tw (Han).
E-mail: d03b45003@ntu.edu.tw (Hsu)
2Institute of Information Science, Academia Sinica, Taipei, Taiwan. E-mail: t050508@gmail.com (Chuang); lindalu@iis.sinica.edu.tw (Lu); cylin@iis.sinica.edu.tw (Lin)

(Received 2 June 2022 / Accepted 25 October 2022 / Published 10 March 2023)
Communicated by John Wang

The Japanese eel (Anguilla japonica) is an important species in East Asian aquaculture. However, the production of seedlings for this purpose still depends on natural resources, as the commercial production of glass eels is not yet possible. Confusion about the sex of silver eels is one of the factors affecting the success rate of artificial maturation. This study sought to devise a harmless method to precisely assess the sex of silver eels. Partial pectoral fins were collected from females and males and the total RNA was extracted for transcriptomic analysis to identify sexually dimorphic genes as molecular markers for sex typing. An online database was constructed to integrate the annotations of transcripts and perform comparative transcriptome analysis. This analysis identified a total of 29 candidate sexually dimorphic genes. Ten were selected for a real-time quantitative polymerase chain reaction (RT-qPCR) to validate the transcriptomic data and evaluate their feasibility as markers. The transcriptomic analysis and RT-qPCR data implicated three potential markers (LOC111853410, kera, and dcn) in sex typing. The expression of LOC111853410 was higher in females than in males. In contrast, the expression of kera and dcn was higher in males than in females. The ΔCT values of three markers were analyzed to determine their inferred thresholds, which can be used to determine the sex of Japanese eels. The results suggested that if a silver eel had a pectoral fin with the pectoral fin having the ΔCT of LOC111853410 < 11.3, the ΔCT of kera > 11.4, or the  ΔCT of dcn > 6.5 can be assessed it could be assessed as female. Males could be assessed by the ΔCT of LOC111853410 > 11.3, the ΔCT of kera < 11.4, or the ΔCT of dcn < 6.5 in their pectoral fins. The molecular functions of these markers and the biological significance of their differential expression require further exploration.

Key words: Comparative transcriptome analysis, Japanese eel, Pectoral fin, Sex typing, Sexually dimorphic genes.

Citation: Hsu HY, Chuang CH, Lu IH, Lin CY, Han YS. 2023. Identification of sexually dimorphic genes in pectoral fin as molecular markers for assessing the sex of Japanese silver eels (Anguilla japonica). Zool Stud 62:02. doi:10.6620/ZS.2023.62-02.

Supplementary materials: Table S1Table S2Table S3Table S4Fig. S1Fig. S2Fig. S3