Liu Meimei, Zhang Yan, Feng Lang, Guo Qing, Chen Ting, Mu Changkao, Lu Jianfeng, Cheng Yongxu, Wu Xugan
Jiangsu Key Laboratory of Marine Bioresources and Environment, Jiangsu Ocean University, Lianyungang 222005, China.
Centre for Research on Environmental Ecology and Fish Nutrition of Ministry of Agriculture and Rural Affairs, Shanghai Ocean University, Shanghai 201306, China.
Comp Biochem Physiol A Mol Integr Physiol. 2025 Mar;301:111798. doi: 10.1016/j.cbpa.2024.111798. Epub 2024 Dec 31.
The present study investigated the changes of expression and localization of PtVg mRNA, tissue Vg/ Vn concentrations, the contents of progesterone and 17ß-estradiol during the ovarian development of P. trituberculatus. The results showed that: 1) The most abundant mRNA levels of PtVg were found in stage IV, and hepatopancreatic PtVg mRNA was markedly greater than that in ovaries from stage II to stage V. The positive signal of PtVg mRNA was found in the follicular cells (FC), the cytoplasm of previtellogenic oocytes (PRO) and endogenous vitellogenic oocytes (EN), and hepatopancreatic fibrillar (F) cells and resorptive (R) cells. 2) The ovarian Vn contents reached the peak at stage V. In the hemolymph and hepatopancreas, the level of Vg/Vn markedly increased from stage II to stage IV. Immunohistochemistry findings confirmed that the PtVg protein was primarily distributed in the FC and the oocyte cytoplasm of late stages (II-V). 3) The highest levels of progesterone in the ovaries, hepatopancreas and hemolymph all appeared in stage II and then declined gradually from stage II to stage V. Ovarian 17β-estradiol concentration show an increasing trend from stage I to IV and remarkably decreased at stage V, while the peak levels of 17β-estradiol in hepatopancreas and hemolymph was found in stage III. 4) Positive correlations were found between ovarian and hepatopancreatic 17β-estradiol content and the corresponding Vg mRNA level, while significantly negative correlations were found between the tissue progesterone titers and the corresponding GSI or Vg/Vn contents during ovarian maturation. In conclusion, the vitellogenesis characteristics of P. trituberculatus are stage-specific, and most vitellogenin is produced by the hepatopancreas, which is also highly correlated to the changes of tissue 17β-estradiol content during the ovarian developmental cycle.
本研究调查了三疣梭子蟹卵巢发育过程中PtVg mRNA的表达和定位变化、组织Vg/Vn浓度、孕酮和17β-雌二醇含量。结果表明：1）PtVg mRNA水平在IV期最高，肝胰腺中PtVg mRNA明显高于II至V期卵巢中的水平。在滤泡细胞（FC）、卵黄发生前卵母细胞（PRO）和内源性卵黄发生卵母细胞（EN）的细胞质以及肝胰腺纤维细胞（F）和吸收细胞（R）中发现了PtVg mRNA的阳性信号。2）卵巢Vn含量在V期达到峰值。在血淋巴和肝胰腺中，Vg/Vn水平从II期到IV期显著增加。免疫组织化学结果证实，PtVg蛋白主要分布在晚期（II-V）的FC和卵母细胞细胞质中。3）卵巢、肝胰腺和血淋巴中孕酮的最高水平均出现在II期，然后从II期到V期逐渐下降。卵巢17β-雌二醇浓度从I期到IV期呈上升趋势，在V期显著下降，而肝胰腺和血淋巴中17β-雌二醇的峰值水平出现在III期。4）卵巢和肝胰腺中17β-雌二醇含量与相应的Vg mRNA水平呈正相关，而在卵巢成熟过程中，组织孕酮滴度与相应的GSI或Vg/Vn含量呈显著负相关。总之，三疣梭子蟹的卵黄发生特征具有阶段特异性，大多数卵黄蛋白原由肝胰腺产生，这也与卵巢发育周期中组织17β-雌二醇含量的变化高度相关。
