Lihua Qiu

This study investigated the effects of Rhodiola rosea extract supplementation on liver morphology, antioxidant capacity, inflammatory response, insulin signaling pathway, and glucose metabolism in Lateolabrax maculatus (9.37±0.14g). Three experimental diets were prepared: a control group (20% carbohydrate), a high-carbohydrate (HC) group (30% carbohydrate), and a high-carbohydrate with Rhodiola rosea extract (HCR) group (30% carbohydrate + 120 mg/kg Rhodiola rosea extract). The HC group showed significant increases in survival rate (SR), hepatosomatic index (HSI), triglyceride (TG), and liver malondialdehyde (MDA) levels, along with increased liver vacuoles, blurred cell boundaries, and larger lipid droplets. Additionally, the expression levels of Keap1, NF-κB, IKKβ, TNF-α, IL-8, IL-12p40, AKT2, SOCS3, GK, PEPCK, FBP, and GSK3β mRNA in hepatic tissue were markedly higher than in the control group (p < 0.05). Conversely, liver activities of T-AOC and CAT, and mRNA levels of CAT, HO-1, Nrf2, and TGF-β were significantly lower (p < 0.05). Compared to the HC group, the HCR group exhibited significant increases in SGR, plasma indices of INS, LA, PA, and liver enzyme activities of T-AOC and SOD (p < 0.05), as well as elevated mRNA levels of CAT, TGF-β, PI3Kα, PI3Kβ, GK, PK, and PFK in the liver (p < 0.05). Histological analysis revealed that hepatocytes in the HCR group had a higher concentration of nuclei, and the size and quantity of lipid droplets were reduced compared to the HC group. Furthermore, liver glycogen, plasma indices of TG and ALT, and liver enzyme activities of PEPCK, HK, and CAT decreased in the HCR group (p < 0.05). The expression levels of Keap1, IKKβ, IL-8, IL-12p40, NF-κB, IFN-γ2, SOCS3, TNF-α, FBP, G6Pase, and GSK3β mRNA were also reduced in the HCR group compared to the HC group (p < 0.05). In conclusion, Rhodiola rosea extract supplementation at 120 mg/kg in high-carbohydrate diets can mitigate the adverse effects of carbohydrate-rich diets on Lateolabrax maculatus by improving glucose metabolism and enhancing defenses against oxidative stress and inflammation.

Background: Primordial germ cells (PGC) are the progenitor cells of sperm and eggs during the embryonic stage. The maternal gene vasa has been widely studied for its role in PGC origin, and other genes like dead end (dnd) have also been identified. Objectives: Spotted sea bass is an important economic marine fish, and the study of its germ cell characteristics provides important basic data for future population breeding and protection. Methods: In this study, we cloned the full-length sequences of Lmvasa (2384 bp, encoding 1905 aa) and Lmdnd (1523 bp, encoding 386 aa) using RACE. Temporal and spatial expression patterns of Lmvasa and Lmdnd in embryos and gonads were analyzed by PCR, immunohistochemistry, and in situ hybridization. We also used microinjections of chimeric RNA containing GFP and Lmvasa 3′ UTR to visualize PGCs. Results: Our results showed that Lmvasa and Lmdnd are expressed primarily in early embryonic development (pre-blastula stage) and were expressed only in the gonads. Immunohistochemistry revealed abundant expression of Lmvasa and Lmdnd proteins in spermatogonia, weak expression in spermatocytes, and no expression in spermatozoa. In ovaries, both genes were expressed throughout oogenesis. Furthermore, PGCs in spotted sea bass belonged to an early localization pattern. Microinjection experiments demonstrated that Lmvasa 3′ UTR effectively labeled PGCs in embryos of spotted sea bass, zebrafish, and medaka. Conclusions: These findings may contribute to understanding PGC development in spotted sea bass and other Percidae.

Fish reproduction requires suitable salinity and temperature, as well as sufficient energy. This study investigated temperature and salinity effects on ovarian development of Lateolabrax maculatus and energy metabolism differences between reproduction and growth. Two salinities (4‰ and 30‰) and temperatures (18 ± 1 °C and 30 ± 1 °C) formed four treatments: SWNT (30‰, 30 ± 1 °C), SWLT (30‰, 18 ± 1 °C), FWLT (4‰, 18 ± 1 °C), and FWNT (4‰, 30 ± 1 °C). GSI and sex hormones (FSH, LH, E2, and 17α,20β-DHP) were measured. Transcriptome analysis explored how temperature and salinity regulate ovarian development in L. maculatus, while integrated transcriptomic and targeted energy metabolomic analyses revealed energy metabolism differences between ovary and muscle during this process. The results showed that low salinity (4‰) and low temperature (18 ± 1 °C) synergistically promoted ovarian development in the FWLT group, as indicated by a significant increase in GSI and elevated levels of key sex hormones (FSH, LH, E2, and 17α,20β-DHP). Transcriptome analysis showed that low temperature activated pathways involved in steroidogenesis, oocyte maturation, and meiosis, and genes such as ADCY6, PRKACB, CPEB4, FZD7-A, and CCND2 were significantly upregulated. Salinity changes mainly affected amino acid metabolism, cholesterol metabolism, and the insulin signaling pathway. Genes such as PCSK9 and CKM may regulate ovarian development by regulating hormone synthesis and energy metabolism. Comprehensive transcriptome and metabolome analyses show that glycolysis is downregulated and oxidative phosphorylation is upregulated in the ovary, suggesting that ovarian oogenesis tends to be energized by aerobic metabolism. The TCA cycle may be used more for providing biosynthetic precursors and facilitating the transport of substrates between the mitochondrion and the cytoplasm rather than just as a source of ATP. Muscle tissue relies primarily on glycolysis for rapid energy production and may redistribute energy to the gonads, prioritizing the energy needs of the ovaries and contributing to the dynamic balance between reproduction and growth. This study provides insights into the molecular mechanisms of how environmental factors regulate fish reproduction, providing a theoretical basis and potential molecular targets for the regulation of reproduction and optimization of aquaculture environments.