Analysis of a sex-biased sequence in sex determination region and exploitation of a fast sex detection method in Litopenaeus vannamei

In order to understand the characteristics of the sex determination region in Litopenaeus vannamei, genome walking was performed based on the existing sex-linked Marker19299. A fragment of 2630 bp sequence was obtained for the genomic DNA of females, which contains two contigs, contig 122401 and contig 4497889. On contig 122401, the sequence showed a sex-biased amplification between females and males, the target band for males was much weaker than that for females. Copy number analysis showed that the female DNA contained more copies of contig 122401 sequence than that of males. Besides, the females contained an extra 9 bp insertion and a 205 bp repeat on contig 4497889 in comparison with males. These results not only provide further evidence for the ZZ/ZW sex determination system in Litopenaeus vannamei, but also suggest a novel hypothesis that the sex determination in L.vannamei might be controlled by the existence of the differences both in DNA sequence and genome structure. According to the above characteristics, a fast detection method to distinguish genetic sex of L.vannamei was developed. This research will not only provide useful information for the fine mapping of the sex determination region in L.vannamei, but also accelerate studies about the sex determination mechanism in shrimp.