Abstract
Sex-specific markers play an important role in revealing sex-determination mechanism. Sea urchin (Mesocentrotus nudus) is an economically important mariculture species in several Asian countries and its gonads are the sole edible parts for people. However, growth rate and immunocompetence differ by sex in this species, sex-specific markers have not been identified, and the sex-determination mechanism of sea urchin remains undetermined. In this study, type IIB endonuclease restriction-site associated DNA sequencing (2b-RAD-seq) and a genome survey of M. nudus were performed, and three female-specific markers and three female heterogametic single nucleotide polymorphism (SNP) loci were identified. We validated these sex-specific markers via PCR amplification in a large number of individuals, including wild and artificially bred populations. Several open reading frames (ORFs) were predicted, although there are no potential genes known for sex determination and sex differentiation within the scaffold in which the sex-specific markers are located. Importantly, the female-specific sequences and female heterozygous SNP loci indicate that a female heterogametic and male homogametic ZW/ZZ sex-determination system should exist in M. nudus. The results provide a solid basis for revealing the sex-determination mechanism of this species, and open up new possibilities for developing sex-control breeding in sea urchin.
Highlights
Sexual dimorphism is common in aquaculture animals, and growth rate, immunocompetence, and body size generally differ significantly by sex (Mei and Gui, 2015; Jiang et al, 2017)
Sex-Specific Markers in Sea Urchin linked to sexual dimorphism in urchins (Osako et al, 2007; Martínez-Pita et al, 2010; Díaz de Vivar et al, 2019)
To confirm the authenticity of the candidate sex-specific tags and single nucleotide polymorphism (SNP), primers were designed according to the flanking sequences of the 2b-RAD tags and SNPs from the genome survey (Table 5)
Summary
Sexual dimorphism is common in aquaculture animals, and growth rate, immunocompetence, and body size generally differ significantly by sex (Mei and Gui, 2015; Jiang et al, 2017). Edible sea urchins are important mariculture species in several Asian countries. This group of animals shows gender-specific differences in immune response, for example, the immunocompetence of female Paracentrotus lividus urchins might be superior to that of males (Arizza et al, 2013). Most sea urchins lack conspicuous sexually dimorphic phenotypes, making it impossible to distinguish the phenotypic sex of living animals This dramatically increases the costs and reduces the efficiency of genetic breeding. Amplified fragment length polymorphism (AFLP) is a traditional method to score random SNP markers across an entire genome This approach is expensive and requires complex experiments (Griffiths and Orr, 1999; Flachowsky et al, 2001). Our results can be used to significantly improve breeding efficiency, and provide useful information for understanding the sex-determination mechanisms in sea urchins
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
