Department of Zoology, Queen Mary's College (Autonomous), Affiliated to the University of Madras, Chennai 600004, Tamil Nadu, India; Endocrinology Unit, Department of Zoology, Madras Christian College, Affiliated to the University of Madras, Chennai, India.
Department of Zoology, Queen Mary's College (Autonomous), Affiliated to the University of Madras, Chennai 600004, Tamil Nadu, India.
Gen Comp Endocrinol. 2023 Jan 15;331:114118. doi: 10.1016/j.ygcen.2022.114118. Epub 2022 Aug 28.
Marphysa madrasi is a commercially valuable maturation diet in crustacean aquaculture. This study presents the first detailed investigation of oogenesis in the intertidal polychaete worm M. madrasi and reports the steroid profile during oocyte growth and development. Oogenesis is extraovarian type I, originating from coelomic epithelial cells, with four stages of development - primary growth, early vitellogenic, late vitellogenic, and maturation. The primary growth phase contains oogonial cells and previtellogenic oocyte clusters in the early, mid, and late stages of development form a dispersed ovary attached to blood vessels. The late previtellogenic oocytes detach from the ovary at the onset of vitellogenesis. The detached oocytes complete vitellogenesis and final maturation in the coelomic fluid as solitary free-floating cells without any connection with follicle cells. The worms display asynchronous reproduction with a heterogeneous population of developing oocytes. Steroid extracts from the polychaete homogenates in different stages of oogenesis were identified by HPLC and confirmed by LC-MS/MS. In M. madrasi, two vertebrate-type steroids, pregnenolone (P5) and 17α-hydroxyprogesterone (17-OHP) were detected and quantified. The P5 levels were low in immature worms but increased significantly by ∼ 8.3-fold in the previtellogenic stage and peaked during oocyte maturation. 17-OHP levels were low in immature worms but gradually increase as the oogenesis progress to the primary growth and early vitellogenic phase, with a significant increase (p < 0.001) during the late vitellogenic phase. Although an increase in the concentration of P5 and 17-OHP during vitellogenesis and maturation of oocytes points to a possible role in reproduction, the absence of other vertebrate-type steroids in the investigated polychaete signifies a plausible uptake of P5 and 17-OHP from the environment.
马氏沼虾是甲壳类水产养殖中具有商业价值的成熟饲料。本研究首次详细研究了潮间带多毛类蠕虫马氏沼虾的卵发生，并报告了卵母细胞生长和发育过程中的类固醇谱。卵发生是卵巢外的 I 型，起源于体腔上皮细胞，有四个发育阶段-初级生长、早期卵黄生成、晚期卵黄生成和成熟。初级生长阶段包含卵原细胞和前卵黄生成卵母细胞簇，在早期、中期和晚期发育阶段形成附着在血管上的分散卵巢。晚期前卵黄生成卵母细胞在卵黄生成开始时从卵巢上脱落。脱落的卵母细胞在体腔液中完成卵黄生成和最终成熟，成为游离漂浮的单个细胞，与滤泡细胞没有任何联系。该蠕虫表现出不同步的繁殖，具有不同发育阶段的卵母细胞的异质群体。通过 HPLC 鉴定和 LC-MS/MS 确认，从多毛类动物不同卵发生阶段的匀浆中提取了两种脊椎动物类型的类固醇，孕烯醇酮（P5）和 17α-羟孕酮（17-OHP）。P5 水平在不成熟的蠕虫中较低，但在前卵黄生成阶段显著增加了约 8.3 倍，并在卵母细胞成熟时达到峰值。17-OHP 水平在不成熟的蠕虫中较低，但随着卵发生进展到初级生长和早期卵黄生成阶段逐渐增加，在晚期卵黄生成阶段有显著增加（p<0.001）。尽管卵黄生成和卵母细胞成熟过程中 P5 和 17-OHP 浓度的增加表明它们可能在繁殖中发挥作用，但在所研究的多毛类动物中缺乏其他脊椎动物类型的类固醇表明，P5 和 17-OHP 可能是从环境中摄取的。
