Species-specific ammonia tolerance in the marine rotifers Brachionus plicatilis and Brachionus rotundiformis: Reproductive characteristics and its mechanisms
Species-specific ammonia tolerance in the marine rotifers Brachionus plicatilis and Brachionus rotundiformis: Reproductive characteristics and its mechanisms
复制标题
海洋轮虫褶皱臂尾轮虫和圆形臂尾轮虫的物种特异性氨耐受性：繁殖特性及其机制
DOI：
10.1016/j.aquaculture.2021.737837
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发表时间：
2022
期刊：
影响因子：
4.5
通讯作者：
Hagiwara Atsushi
中科院分区：
文献类型：
--
作者：
Han Chengyan;Kim Hee-Jin;Sakakura Yoshitaka;Hagiwara Atsushi
高游离氨（NH3−N）是养殖水生动物的主要应激因子，可使养殖设施中轮虫的群体养殖崩溃。在轮虫群体培养中，当达到最大密度时，NH3-N浓度升高。由于NH3-N毒性具有温度依赖性，热带和温带轮虫应受到不同水平的生境资源NH3-N的影响，这可能会影响它们的生理适应。为了研究轮虫对不同生境的生殖适应性及其对NH3-N的耐受性，本研究对桡臂轮虫种群复合体中的两个轮虫种群进行了研究。plicatilisand tropicalB。rotundiformis。评估急性（致死）和慢性（亚致死）NH3-N暴露下的生存、生活史参数和生殖模式。不处理NH3-N或分别暴露于1.1和8.5 mg/L NH3-N环境7 d，以确定氨敏感性的生化（即氧化代谢和脂质代谢）和行为（游泳速度）机制。高浓度NH3-N（≥8.5 mg/L）抑制了轮虫的生长和繁殖，导致两种轮虫的成熟迟缓和繁殖力下降。然而，热带b。对急性和慢性NH3-N暴露的耐受性优于温度b。25°C时，其lc50和EC50（固有生长率）值分别提高1.5倍和1.7倍。此外,B。在性生殖参数中，包括混合、受精和静息产卵，轮虫表现出较强的氨耐受性。高有性生殖耐受性是提高轮虫抗逆性和在恶劣环境下维持种群的重要手段。两种植物在NH3-N暴露下表现出不同的脂质调节和应激防御活性。TemperateB。在生殖器官（卵黄/卵巢）中性脂质积累减少，高水平丙二醛（MDA）刺激脂质过氧化，破坏抗氧化活性。相比之下，热带b。轮状二甲酸酯表现出积极的防御反应，具有增强的抗氧化活性和脂质合成。这些分子证据表明，热带和温带轮虫具有特定的氨敏感性，热带轮虫比温带轮虫具有更积极的抗应激策略，从而具有较高的氨耐受性。热带b的耐氨性较高。在大规模培养过程中，圆形异种可能支持它们的高密度耐力。
High unionized ammonia (NH3−N) is a major stress factor for rearing aquatic animals that can collapse the mass culture of rotifers in aquaculture facilities. In rotifer mass culture, concentrations of NH3-N are elevated when reaching maximum density. As NH3-N toxicity has temperature-dependent characteristics, tropical and temperate rotifers should be subjected to different levels of habitat-resource NH3-N, which could affect their physiological adaptations. To investigate the NH3-N tolerance of rotifers associated with reproductive adaptations to different habitats, two rotifer species in theBrachionus plicatilisspecies complex were studied: temperateB. plicatilisand tropicalB. rotundiformis. Survival, life history parameters, and reproductive patterns were assessed under acute (lethal) and chronic (sub-lethal) NH3-N exposure. These rotifer species were not treated with NH3-N or exposed to 1.1 and 8.5 mg/L NH3-N for 7 days to define the biochemical (i.e., oxidative and lipid metabolism) and behavioral (swimming speed) mechanisms of ammonia species sensitivity. High concentrations of NH3-N (≥8.5 mg/L) suppressed rotifer growth and reproduction, resulting in substantial maturation retardation and fecundity reduction in both species. Nevertheless, the tropicalB. rotundiformiswas more tolerant to acute and chronic NH3-N exposure than the temperateB. plicatilis, with 1.5 and 1.7 fold higher LC50and EC50(for intrinsic growth rate) values at 25 °C, respectively. Furthermore,B. rotundiformisshowed stronger ammonia tolerance in sexual reproductive parameters, including mixis, fertilization, and resting egg production. High sexual reproduction tolerance is important for improving rotifer stress resistance and maintaining the population under harsh environments. The two species exhibited different modulations of lipid and stress defense activities under NH3-N exposure. TemperateB. plicatilisshowed reduced neutral lipid accumulation in the reproductive organs (vitellarium/ovary), stimulated lipid peroxidation with a high level of malondialdehyde (MDA), and disrupted antioxidant activities. In contrast, the tropicalB. rotundiformisexhibited active defense responses, with enhanced antioxidant activity and lipid synthesis. These findings with molecular evidence indicate the specific ammonia sensitivity between tropical and temperate rotifers, and more active anti-stress strategies of the tropical species than the temperate species, contributing to high ammonia tolerance. The higher ammonia tolerance of tropicalB. rotundiformisspecies may support their high-density endurance during mass culture.