Studies on Species Identification by Using PCR-RFLP Technique and Level of Vitamin A and Toxicity in Livers of Common Groupers in Taiwan

• Main Authors: Po-Ming Tsai, 蔡博名
• Other Authors: Deng-Fwu Hwang
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/79457814611195983720

碩士 === 國立臺灣海洋大學 === 食品科學系 === 98 === Groupers are commercially important fish species in Taiwan. These fish distribute in the tropical and subtropical coral reef district around the world and are carnivorous and edible important species. But they are recognized as species of ciguatera commonly. Ciguatoxin is produced by Gambierdiscus toxicus which is usually attached on coral. The toxin and related compounds are first accumulated in herbivorous fish and then transferred into carnivorous fish via food chain. When human consume these toxic herbivorous or carnivorous fish, they may be intoxicated. Grouper’s livers also have been recorded to accumulate ciguatoxin and vitamin A. Grouper’s size was usually large and was cut into pieces for sell in the markets. So the morphological characteristics have been removed, resulting in changes of the species appearance or muscle quality and unable identifying. In order to identify the fish species, gene sequencing and polymerase chain reaction – restriction fragment length polymorphism (PCR-RFLP) were used in this study. Using the pair of primers (L14735 / H15149ad) could successfully amplify tRNAGlu / cytochrome b gene of the 15 common groupers in Taiwan. The lengths of these partial tRNAGlu / cyt b gene regions were 462-469 bp. These fragments could be amplified using fish meat treated with different heating processes (100oC for 15 min, 100oC for 30 min, 121oC for 15 min, and 121oC for 30 min). After sequencing, it was found that no significant variation in sequence among individuals within each species. Using restriction enzyme analysis by Hae III, Hinf I and Alu I could distinguish these 15 species of grouper rapidly. The developed PCR-RFLP method was applied to identify species of 12 commercial grouper fillets in the markets of Keelung City. Wild and cultured groupers (Epinephelus malabaricus) with different body weights were collected from Anping Harbor, Tainan. The level of vitamin A in the liver was analyzed by high performance liquid chromatography (HPLC). The average level of vitamin A in wild E. malabaricus liver was 6,930 ± 2,340 IU/g (Mean ± SD, n = 6) and in cultured E. malabaricus was 823 ± 516 IU/g (Mean ± SD, n = 6). Regression model shows that the more body weight and liver weight, the higher vitamin A level in liver of wild and cultured E. malabaricus. The vitamin A level in liver of wild E. malabaricus was significantly higher than the level in liver of cultured E. malabaricus. However, the ciguateric toxins of liver in 12 specimens of wild and cultured E. malabaricus were not detected.