| Summary: | 碩士 === 國立臺灣海洋大學 === 水產養殖學系 === 94 === The objectives of the present study were to investigate the molecular role of AVT and AVTR V1 genes in the sexual development and salinity tolerance of the protandrous black porgy (Acanthopagrus schlegeli). The variation of AVT and AVTR V1 gene expression was studied at different reproductive development stage of black porgy, especially in relation to sex differentiation. Changes in the gene expression after administration of sex steroids were also investigated.
Gonadal sex differentiation in black porgy occurs between 120~150 dah (days after hatching), but hypothalamus AVT gene increased significantly at 120 dah, indicating that AVT might be related to sex differentiation in black porgy. Hypothalamus AVT gene increased significantly during spawning season of 1~3 year old black porgy. In contrast, in the forebrain, AVT gene increased significantly during non-spawning season of 1 and 2 year old fish. Therefore, we suggest that expression of hypothalamus AVT gene might be related to gonadal development and maturation or sex behaviors of black porgy.
Oral administration of ATD for 15 days resulted in a significant increase in the expression of hypothalamus AVT gene and gonad AVTR V1 gene, whereas oral administration of ATD for 45 days resulted in a significant decease in the expression of midbrain and hypothalamus AVT gene and an increase in the expression of gonad AVTR V1 gene.
Injection of high dose 11-ketotestosterone caused a significant increase in the expression of hypothalamus AVT. In contrast, testosterone and 17β estradiol had no significant influence on hypothalamus AVT. Thus, we suggest that sex steroids could influence the gene expression of AVT in a dose dependent manner.
Transfer of black porgy from freshwater to seawater for 8 hours resulted in a significant increase in the expression of hypothalamus AVT gene, while transfer from seawater to freshwater for 3 days resulted in a significant decrease in the expression of hypothalamus AVT gene. Oral administration of high dose cortisol for 7 days caused a significant decrease in the expression of hypothalamus AVT gene, but the regulatory mechanism is still unclear.
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