低氧胁迫对抗流F1代大黄鱼低氧应答基因与抗氧化相关酶活性及其组织结构的影响

Effects of hypoxia stress on hypoxia response genes, antioxidant-related enzyme activities, and tissue structure in flow-resistant F1 generation of Larimichthys crocea

  • 摘要: 【目的】 明确抗流 F1代(FDTL)大黄鱼的耐低氧适应策略及其分子机制,为大黄鱼耐低氧抗流新品系的进一步选育提供理论支撑,也为优化深远海大黄鱼养殖环境调控方案及保障其产业高质量发展提供科学依据。【方法】 以养殖26个月的FDTL大黄鱼与非选育组(FDCL)为研究对象,经低氧(溶解氧含量2.0±0.1 mg/L)胁迫24 h,分别于低氧胁迫0、6、12、18及24 h等5个时间点采集大黄鱼肝脏、肾脏及鳃组织等样品,用于检测肝脏低氧应答相关基因表达、各组织抗氧化及代谢相关酶活性,以及制作鳃组织切片。【结果】低氧胁迫24 h后,FDTL大黄鱼肝脏中ddit4gadd45bpfkfb3egln3angpt2serpine1atf3hspb7等8个低氧应激相关基因的相对表达量极显著低于FDCL大黄鱼(P<0.01,下同),而cpt1bgclm基因的相对表达量显著(P<0.05,下同)或极显著高于FDCL大黄鱼。低氧胁迫过程中,FDCL大黄鱼和FDTL大黄鱼的各组织氧化应激与代谢相关指标呈现不同的时间动态响应及组间差异。FDTL大黄鱼肝脏和鳃组织中的丙二醛(MDA)含量波动变化相对平缓,肾脏组织中的MDA含量显著或极显著低于FDCL大黄鱼;谷胱甘肽过氧化物酶(GSH-Px)、过氧化氢酶(CAT)等核心抗氧化酶活性在多数时间点高于FDCL大黄鱼,且各种酶活性协同优化;肝脏和肾脏组织中的PK活性峰值均集中出现在低氧胁迫中期(12 h),与机体在应激中期的能量需求高峰高度契合。FDTL大黄鱼在低氧胁迫6 h时,其鳃组织仍保持结构完整,仅在胁迫18 h后出现轻微实质性细胞坏死与毛细血管淤血,且各时间点均未出现炎性细胞浸润,对低氧环境的耐受性明显优于FDCL大黄鱼。【结论】FDTL大黄鱼通过下调ddit4gadd45b等应激基因表达、上调cpt1bgclm基因表达而构建高效分子调控网络,各组织代谢酶及抗氧化酶活性呈时序适配性特征,且其鳃组织具有更强的结构稳定性与抗损伤能力,即FDTL大黄鱼的耐低氧优势源自“分子调控—生理适配—组织稳定”的多维度协同作用,其核心是拥有更低的低氧耐受阈值及高效的代谢重编程能力,且鳃组织抗损伤能力更强。

     

    Abstract: 【Objective】 This study aimed to elucidate the hypoxia adaptation strategies and molecular mechanisms of the flow-resistant F1 generation (FDTL) of Larimichthys crocea, thereby providing theoretical support for breeding hypoxia-tolerant and flow-resistant strains, as well as scientific basis for optimizing environmental regulation in deep sea aquaculture to ensure high-quality industrial development. 【Method】 FDTL Larimichthys crocea cultured for 26 months and non-selected Larimichthys crocea (FDCL) were subjected to hypoxia stress (dissolved oxygen 2.0 ±0.1 mg/L) for 24 h. Liver, kidney, and gill tissues were collected at 5 time points (0, 6, 12, 18, and 24 h of hypoxia stress) to analyze expression of hypoxia response genes in liver and activities of antioxidant and metabolic enzymes in tissues, with gill sections were made. 【Result】 After 24 h of hypoxia stress, the relative expression of 8 hypoxia stress-related genes (ddit4gadd45bpfkfb3egln3angpt2serpine1atf3hspb7) in the liver of FDTL Larimichthys crocea was extremely significantly lower than that in FDCL Larimichthys croceaP<0.01, the same below), whereas the expression of cpt1b and gclm was significantly (P<0.05, the same below) or extremely significantly higher than that in FDCL Larimichthys crocea. During hypoxia stress, the different temporal dynamic responses and differences between groups in indicators related to oxidative stress and metabolism in tissues were found between FDCL and FDTL Larimichthys crocea. The malondialdehyde (MDA) content in liver and gill tissues of FDTL Larimichthys crocea fluctuated relatively mildly, and the MDA content in kidney was significantly or extremely significantly lower than that in FDCL Larimichthys crocea. Activities of core antioxidant enzymes such as glutathione peroxidase (GSH-Px) and catalaes (CAT) were generally higher than those in FDCL Larimichthys crocea at most time points, with coordinated optimization among enzyme activities. The peak pyruvate kinase (PK) activity in liver and kidney tissues occurred at the mid-hypoxia stage (12 h), closely mat-ching the peak energy demand during the mid-stress stage. At 6 h of hypoxia stress, the gill tissue of FDTL Larimichthys crocea remained structurally intact; mild parenchymal cell necrosis and capillary congestion appeared only after 18 h of stress, and no inflammatory cell infiltration was observed at any time point, indicating significantly greater tolerance to hypoxic environment compared with FDCL Larimichthys crocea. 【Conclusion】 FDTL Larimichthys crocea establishes an efficient molecular regulatory network by down-regulating expression of stress-responsive genes such as ddit4 and gadd45b while up-regulating expression of cpt1b and gclm genes. The activities of metabolic and antioxidant enzymes in tissues exhibit temporal adaptation characteristics, and the gill tissue shows stronger structural stability and anti-damage capacity. The advantage of hypoxia tolerance of FDTL Larimichthys crocea comes from a multi-dimensional synergy of “molecular regulation-physiological adaptation-tissue stability”, with the core being a lower threshold for hypoxia tolerance, efficient metabolic reprogramming, and enhanced resistance to gill tissue damage.

     

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