Immunochemical Properties of Vitellogenins and Egg Yolk Proteins in Female Fusilier, Caesio diagramma

농어목 어류, Caesio diagramma의 vitellogenin과 난황단백의 면역화학적 특성

This study was conducted to compare the immunochemical properties of female-specific serum proteins (vitellogenin, VTG) and egg yolk proteins in female fusilier, Caesio diagramma. VTG of fusilier was identified and characterized by using immunochemical analysis. Two types of VTG (VTG1 and VTG2) reacted clearly with antiserum against egg proteins, were confirmed in the serum of mature female. The results of sephacryl S-300 showed that the molecular weights of VTG1 and VTG2 were 560,000 and 410,000, respectively. Yolk proteins, E2 and E3, were isolated from egg extracts, and molecular weights of them were estimated 410,000 and 170,000, respectively. The treatment of $17\beta$-estradiol ($E_2$) to males has induced the synthesis of VTG of which immunological characteristics seems to be similar to the yolk proteins. The results suggest that VTG can be synthesized in the liver by the action of $E_2$ stimulation, and incorporated into the oocytes through the blood circulation. The level of serum $E_2$ was moderately high throughout the spawning period of June. The level of serum VTG was also sustained at high in May and June. The concentration changes of serum $E_2$ and VTG were corelated to the ovarian development in female fusilier. The results indicated that $E_2$ may have some important roles for the vitellogenesis in female fusilier. Also) the VTG can be a precursor protein of yolk not only because it could be synthesized in the liver then incorporated into the oocytes but also because an egg yolk protein had the similiar molecular weights and antigenecity with VTG.

농어목 어류, C. diagramma 암컷의 vitellogenin과 난황단백의 면역화학적 특성을 서로 비교하였다. 면역화학적 방법에 의해 C. diagramma 암컷의 혈청에서 vitellogenin 1 (VTG1)과 vitellogenin 2 (VTG2)를 동정하였으며, sephacryl S-300 gel 여과법에 의하여 측정된 분자량은 각각 560,000과 410,000이었다. 암컷의 난소 추출액에서는 두 가지 형태의 난황단백인 E2와 E3가 분리되었으며, 이들의 분자량은 각각 410,000과 170,000이었다. $17\beta$-estradiol ($E_2$)을 주사한 수컷의 혈청과 간조직을 abidine-biotin complex (ABC) 방법으로 분석한 결과, vitellogenin과 유사한 물질이 검출되었다. 이상의 결과로 부터, 외인성 $E_2$ 에 의해 간에서 합성된 vitellogenin은 혈액 속으로 방출된 후 난소로 이동되는 것으로 추정되었다. 암컷의 $E_2$, 혈중농도는 산란기인 6월에 최고치를 나타내었고, vitellogenin 상대농도도 $5\~6$월에 최고치를 나타내었다. $E_2$와 vitellogenin의 변화는 본 종의 난소성숙과 밀접한 관계가 있으며, 난황형성에 있어서도 중요한 역할을 하고 있음을 알 수 있었다. 암컷 혈청 VTG2와 난소추출액 E2의 분자량이 서로 같고, vitellogenin이 간에서 합성되어 난소내로 이동하는 점으로 보아, 난소내 난황단백 성분의 전구물질은 혈청내의 vitellogenin인 것으로 추정되었다.