農業部-水產試驗所全球資訊網農業部-水產試驗所全球資訊網

本試驗應用PCR-RFLP技術鑑定水產試驗所淡水中心種原庫保存與坊間養殖的雜交單雄性魚粒線體DNA D-loop之差異，旨在瞭解雜交吳郭魚之母系遺傳 (maternal heredity)，與其子代雄性比高低的相關性。電泳結果顯示，經過不同限制酶之切割反應，可判定淡水中心種原庫保存之雜交魚苗粒線體遺傳皆屬一致性的單一尼羅型 (Nile tilapia type)，而坊間的雜交魚則可分為尼羅型、歐利亞型 (Blue tilapia type) 與莫三比克型 (Mozambique tilapia type) 等三型。由上述結果配合外觀型態來判斷，坊間歐利亞型雜交幼魚，其母本係歐利亞吳郭魚 (Oreochromis aureus)，而非尼羅吳郭魚。同樣的，莫三比克型之母本也非尼羅吳郭魚。由此推測，母本混雜非尼羅吳郭魚之結果可能係今日坊間魚苗雄性比例下降的原因。因此，若要得到穩定且高比例雄性之雜交吳郭魚苗，要做好保種管理，以避免使用不純的種魚。

A polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique was used to check the differences of D-loop segment of mitochondrial DNA in the all-male hybrid tilapia progeny, sampled from the aquatic genetic resource bank at the Freshwater Aquaculture Research Center (FARC) and a private fish farm, respectively, in order to elucidate the relationship between the mitochondrial DNA’s maternal heredity and the male ratio of hybrid tilapia progeny.After the digestion of mitochondrial D-loop PCR fragment by different restriction enzymes, the electrophoretic analysis showed that the maternal inheritance of D-loop in the hybrid progeny, sampled from the aquatic genetic resource bank at the FARC, were all identified as ‘Nile tilapia (Oreochromis niloticus) type’, while those sampled from the private fish farm were identified as three categories of ‘Nile tilapia type’, ‘Blue tilapia (O. aureus) type’ and ‘Mozambique tilapia (O. mossambicus) type’.From the above mentioned results and appearance of the hybrid offspring, it was concluded that mother of ‘Blue tilapia type’ hybrid progeny was Blue tilapia, not Nile tilapia. Similarly, mother of ‘Mozambique tilapia type’ was not Nile tilapia. The impurity of maternal broodstock might be the possible reason of the decreasing male ratio of hybrid tilapia progeny in the private fish farm in recent years. In this aspect, it’s important for tilapia aquaculture to increase stable and high ratio of all male hybrid tilapia progeny by management and maintenance of the purity of broodstock.