• Journal of Aquaculture
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• v.20 no.2
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• pp.140-143
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• 2007

Cytogenetic analyses of an endemic species, Coreoleuciscus splendidus (Cyprinidae) was performed including erythrocyte measurement, chromosome count and karyotyping, nucleolar organizing region (NOR) banding and flow cytometric analysis of genome size. C. splendidus had the same modal chromosome number of 2n = 48 between sexes, however, displayed a sex-related dimorphism in their chromosome karyotypes. Males represented a pair of heteromorphic chromosomes which couldn‘t be seen in any female individuals, indicating that the sex determination mechanism of this species should be a typical XX-XY based male heterogamety (female=10M+6SM+8A+XX vs male=10M+6SM+8A+XY). Other cytogenetic features such as Ag-NORs located in a pair of acrocentric chromosomes, estimated nuclear volume ($28{\mu}m^3$) and cellular DNA content (2.4 pg/cell) suggest that genetic recombination might be the main driving force responsible for the evolution of this species rather than the polyploidy-based evolutionary process as in many other Cyprinidae species.

• Fisheries and Aquatic Sciences
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• v.22 no.8
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• pp.18.1-18.5
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• 2019

The development of sex-specific genetic assays in a species provides both a method for identifying the system of sex determination and a valuable tool to address questions of conservation and management importance. In this study, we focused on the identification of single nucleotide polymorphisms (SNPs) that differentiate genetic sex in burbot Lota lota. Burbot are the only true freshwater representative of the cod family and a species of conservation and management importance throughout Eurasia and North America. To identify sex-specific SNPs, we utilized restriction site-associated DNA sequencing (RADseq) to interrogate thousands of SNPs in burbot samples of known phenotypic sex. We discovered 170,569 biallelic SNPs, none of which fit the pattern expected under female heterogamety. However, we identified 22 SNPs that fit the pattern expected under male heterogamety (males heterozygous XY, females fixed XX) and, from these, developed two genetic assays that robustly (~ 97% genotyping success) and accurately (> 99% correct) sexed burbot samples. These sex-specific genetic assays will benefit growing conservation aquaculture programs for this species and allow future assessments of sex-specific migration, growth, and mortality.