Investigation of the utility of PCR-RFLP as a rapid alternative to DNA sequencing for interrogation of the genetic sex of Mugil cephalus

Mugil cephalus is a species of considerable interest for aquaculture. As a species that is not sexually dimorphic, when building a brood stock with a balanced sex ratio there is difficulty for identification of sex until the animals are quite mature. When mono-sex populations of this species is desired, as in the case of production of females for “bottarga”, considerable resource expenditure could be saved if early sorting of sexes were possible to enable selection of a single sex. A recently described sex-associated loci within the follicle stimulating hormone receptor gene (fshr) was identified using genomic DNA sequencing and shown to contain some non-synonymous mutations wherein the females have a tendency to be homozygous and the males heterozygous. The loci identification method is time-consuming and somewhat expensive. We propose that the method described for the identification of the genetic sex of Mugil cephalus, prior to sexual maturation should be rapid and not require DNA sequencing. In this work, we demonstrate the utilization of one of these fshr mutations within this genetic marker in a PCR-RFLP assay. Using this new method, the loci in question shows 77.8 % partitioning with males and 88.9 % partition with females, as referenced to phenotypic sex characterized by histology, thus confirming the partitioning of the genetic marker as seen previously using DNA sequencing. Future applications of this relatively rapid and inexpensive method could contribute to the production of mono-sex farmed stock and open new opportunities for more efficient broodstock management practices in the species.