Development of a serum vitellogenin MRM biomarker for determining sex in American eel (Anguilla rostrata)

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Sex determination in eels is not fixed as in humans and the ratio of males to females is subject to unknown factors, such as environmental cues. Juvenile (glass/elvers) eels grown at commercial densities, were shown to predominantly end up as males (95%). For commercial eel farming, female eels will reach desired market size (>300 g), whereas males mature at a smaller size (<200 g) and do not achieve profitable market size. Success of eel farming will depend on manipulating the sex ratio of eels to increase the proportion of females. Some researchers have demonstrated sex manipulation in European and Japanese eels using ß-estradiol and other estrogenic compounds. The difficulty in developing methods to manipulate sex in eels is that it is best to change the sex in young eels (from 1 -30 g), but it is difficult to determine the sex of eels until they begin to develop maturing gonads (80-150 g). This project intends to develop a cost-effective Liquid Chromatography - Multiple Reaction Monitoring Mass Spectrometry (LC-MRM-MS/MS) method to develop a specific female blood biomarker, vitellogenin, to determine sex in the American eel (Anguilla rostrata) at an earlier stage than is observable by standard microscopic methods. LC-MRM-MS/MS methods will be carried out on blood, and gonad samples from eels sampled in NovaEel's feminization trials. Vitellogenin is a protein synthesized in oviparous animals that is made in the liver and carried in the blood to be delivered to the developing oocytes in the ovaries. It has been used in other fish species as a marker for females. Data will be correlated and validated with gonad development as determined by microscopic methods. Development of cost-effective methods to feminize eels and to rapidly determine the sex of eels will help the company to develop commercially viable eel farming in Eastern Canada.