난황형성과정(Vitellogenesis)은 발달하는 난모세포에 난황이 축적되는 과정으로, 이 과정의 개시는 알형성과정(oogenesis)을 제어하는 주 요 메커니즘이다. 곤충생리학 모델인 노랑초파리(Drosophila melanogaster)에서 난황형성과정은 성충으로 우화한 직후 시작하여 성적 성숙이 일어 나는 2-3일간 지속된다. 성숙한 난모세포가 충분히 만들어지고 성적 성숙이 종료되면, 짝짓기 후 알형성과정이 다시 시작될 때까지 난황형성과정은 멈춘다. 수컷 초파리의 정액 단백질인 성 펩타이드(Sex peptide, SP)는 짝짓기의 신호로서 알라타체(corpora allata)를 자극해 유약호르몬 (Juvenile hormone, JH) 생합성 및 분비를 유도하며, 혈림프(hemolymph) JH 농도의 증가는 난황형성과정을 자극한다. 최근 연구 결과에 따르 면, SP수용체 뉴런은 자궁 내막의 수상돌기를 통해 교미 중 정액과 함께 자궁으로 전달된 SP를 감지함으로써, 축삭돌기를 통해 중추신경계인 복부 신경절에 짝짓기 신호를 보내는데, 이러한 중추신경계 SP 신호가 JH 생합성 및 분비, 그리고 난황형성과정을 유도하는 것으로 밝혀졌다. 짝짓기 후 암컷에서의 난황형성과정은 일주기 리듬을 보이는데, 노랑초파리의 일주기 리듬은 중추 신경계 뉴런들에 의해 제어된다. 본 종설은 성적 성숙, 짝짓기 신호, 그리고 일주기 리듬에 따라 난황형성과정을 제어하는 신경 메커니즘에 관한 최근 연구 성과를 다룬다.

E ffe ct of aluminum (al) on the plasma vite llogenin (VTG) , alkaline-labile phosphorus (ALP P ) , Calcium (Ca) , glutamate pyruvate transaminase (GP T) and hepatosomatic index (H SI ) we re examined in the e stradiol-17β (E 2)-administe red immature rockfish, Sebaste s schlege li. F ish we re intrape r itone ally inje cted with E 2 (5 ㎎/㎏ body we ight (B .W.) ) and/ or Al (0, 0.1, 1, 5 and 10 ㎎/㎏ B .W.) and then plasma we re extracted at 7 days. Thick VTG band was de te cted at a mole cularwe ight position of about 170 kD a in SD S-P AGE using the plasma of E 2-administe red rockfish. This band was reduced by the administration of Al to rockfish. Al reduced the concentrations of ALP P and Ca in a concentration-dependent way and a significant reduction occur red at Al concentrations gre ate r than 5 ㎎/㎏ and 10 ㎎/㎏, re spe ctive ly. The concentration of GP T was incre ased in concentration-dependent way at all the group of Al-administe red rockfish. H SI was reduced in a concentration-dependent way. The se re sults sugge st that Al inte r fe re with E 2-induced vite llogene sis by be ing toxic to hepatocyte .

n re cent ye ars, remarkable conce rn has be en eme rged ove r endocr ine disrupting chemicals (E D Cs) which mimic the e ffe cts of the ste roid hormone and modulate the endocr ine functions of human and wildlife . The biodegradation products of sur factants such as nonylphenol (N P ) have be en regarded as E D Cs. H oweve r , only few studie s have be en car r ied out to inve stigate the e ffe ct of E D Cs on vite llogene sis in mar ine fish. The pre sent study was unde r taken to the e ffe cts of 4-N P on the vite llogene sis of juvenile rockfish, Sebaste s schlege li. J uvenile rockfish we ighing about 50g we re intrape r itone ally inje cted with e stradiol-17β (E 2, 5㎎/㎏ body we ight) or 4-N P in 70% e thanol twice at 3-day inte rvals and blood sampling we re extracted from the fish at 7 days afte r the last inje ction. I ntense VTG bands we re de te cted at mole cular we ight position of about 170kD a in all the plasma of 4-N P -administrated fish as that of E 2-administe red fish. P lasma ALP P , Ca and GP T concentrations we re also incre ased in all the group of 4-N P -administe red fish. The addition of 4-N P to the we lls inhibited the binding activity E 2 to E R in a conve rse sigmoid fashion. The se re sults sugge sted that 4-N P induced VTG synthe sis by the binding affinity 4-N P to E R and acted on E D Cs in the juvenile rockfish

난황형성(vitellogenesis)은 난생동물의 번식에서 매우 중요한 과정으로 간에서 난황전구물질(vitellogenin,Vg)의 생성과 단백질 수준에서 Vg의 변형과 난자내 축적 및 난황물질(vitellin)로의 전환을 포함한다. 난황은 경골어류의 배아의 영양물질 및 삼투압 조절을 통한 부유특성의 조절에 관여한다. 척추동물의 Vg유전자는 lipoprotein계열의 유전자로 복수의 Vg유전자가 존재하며 서로 다른 크기의 Vg단백질을 암호화한다. 에스트

Ultrastructural studies on oocyte differentiation and vitellogenesis in the oocytes of female Kareius bicoloratus were investigated by transmission electron microscopy. The Golgi complex in the cytoplasm is involved in the formation of yolk vesicles that contain yolk carbohydrates in the yolk vesicle of oocytes in the early vitellogenic phase. In this phase, many pinocytotic vesicles (PVs), which are formed by pinocytosis, contain yolk precursors (exogenous substances). These substances are associated with exogenous heterosynthetic vitellogenesis. In yolked oocytes in the late vitellogenic phase, two morphologically different bodies, which formed by modified mitochondria, appear in oocytes. One is a multivesicular body (synthesized by autosynthetic vitellogenesis), and the other is a yolk precursor (an exogenous substance formed by heterosynthetic vitellogenesis). The multivesicular bodies (MVB) are taken into the yolk precursors (YP) and are transformed into primary yolk globules. However, after the YP mix with exogenous PVs near the zona pellucida, they are transformed into primary yolk globules. Vitellogenesis of this species occurs via endogenous autosynthesis and exogenous heterogenesis. Vitellogenesis occurs through endogenous autosynthesis, which involves the combined activity of the Golgi complex, mitochondria and MVB formed by modified mitochondria. However, heterosynthesis involves pinocytotic incorporation of extraovarian precursors (such as vitellogenin in the liver) into the zona pellucida (via granulosa cells and thecal cells) of the yolked oocyte.

Ultrastructural studies on oocyte development and vitellogenesis in oocytes, and the functions of follicle cells during oogenesis and oocyte degeneration were investigated to clarifyb the reproductive mechanism on vitellogenesis of Scapharca subcrenata using electron microscope observations. In this study, vitellogenesis during oogenesis in the oocytes occured by way of autosynthesis and heterosynthesis. Of two processes of vitellogenesis during oogenesis, the process of endogenous autosynthesis involved the combined activity of the Golgi complex, mitochondria and rough endoplasmic reticulum. However, the process of exogenous heterosynthesis involved endocytotic incorporation of extraovarian precursors at the basal region of the oolema of the early vitellogenic oocytes before the formation of the vitelline coat. In this study, follicle cells, which attached to the previtellogenic and vitellogenic oocytes, were easily found. In particular, the follicle cells were involved in the development of previtellogenic oocytes by the supply of nutrients, and vitellogenesis in the early and late vitellogenic oocytes by endocytosis of yolk precursors. Based on observations of follicle cells attached to degenerating oocytes after spawning, follicles of this species are involved in lysosomal induction of oocyte degeneration for the resorption phagosomes (phagolysosomes) in the cytoplasm for nutrient storage, as seen in other bivalves. In this study, the functions of follicle cells can accumulate reserves of lipid granules and glycogen particles for vitellogenesis from degenerating oocytes after spawning.

The effects of the estrogenic compound 4-nonylphenol (4-NP) on vitellogenesis in juvenile olive flounder ( ) and rockfish ( ) exposed continuously at 10, 50 and levels for 7 days were compared. The expression of VTG mRNA level and protein using specific probes were examined. The levels of plasma estradiol-17 and testosterone (T) were assessed by radioimmunoassay (RIA). Plasma concentrations increased significantly in two female fish species exposed to of 4-NP over concentrations in control fish. Plasma T concentrations increased in . Four days after exposure, the level of VTG mRNA expression increased in and exposed to of 4-NP. In addition, plasma VTG protein expression was seen in and . In and exposed to 4-NP, the changes were noticed mainly in hepatocytic vaculation after 7 days of exposure. Thus, 4-NP may disrupt vitellogenesis in immature fish both directly and indirectly via disrupted steroidogenesis and liver pathology. Immature were the most sensitive to 4-NP exposure in vitellogenesis.

갈색띠매물고둥, Neptunea (Barbitonia) arthritica cumingii의 난자 형성과정 중 난황 형성, 생식주기 및 군성숙도를 광학 및 전자현미경적 관찰에 의해서 조사하였다. 초기 난황 형성 단계의 난모세포에서 골지복합체와 미토콘드리아가 지방적 및 난황 과립의 형성에 관여되었다. 후기 난황 형성 단계의 난모세포에서는 조면소포체와 다포체가 세포질 내에서 단백질성 난황 과립 형성에 관여되었다. 성숙 단계 난모세포에서 성숙 난황 과립은 주