Sulfometuron methyl (SM) is a widely used herbicide and thus leading to accumulation in the environment. The toxicity assessments of SM in model organisms are currently rare. In the present study, zebrafish were utilized for evaluating the detrimental effects of SM in aquatic vertebrates. Zebrafish embryos were exposed to 0, 10, 20, and 40 mg/L SM from 5.5 to 72 h post-fertilization (hpf), respectively. Consequently, SM exposure resulted in increasing the mortality rate and reducing hatching rate in larval zebrafish at 10, 20, and 40 mg/L SM-treated groups. The reduced numbers of immune cells (neutrophils and macrophages) were observed after SM exposure by a dose-dependent manner. The inflammatory responses (TLR4, MYD88, IL-1β, IL-6, IL-8, IFN-γ, IL-10, and TGF-β) were measured to estimate immune responses. Anti-inflammatory factors (IL-10 and TGF-β) were down-regulated in all the treated groups and significantly altered at 40 mg/L exposure group. Additionally, behavioral tests suggested that SM treatment significantly increased the total distance, average speed, and maximum acceleration of larval zebrafish during light-dark transition and subsequently enzymology test displayed the same trend to locomotor behaviors. The content significantly increased in oxidative stress, as reflected in ROS level in all the treated groups. The numbers of cell apoptosis were significantly increased at 20, and 40 mg/L and the highest concentration group induced the substantial increment (P < 0.001) of apoptosis-related genes including p53, Bax/Bcl-2, caspase-9, and caspase-3. In summary, our results demonstrated that exposure to SM caused toxicity of development, immune system, locomotor behavior, oxidative stress, and cell apoptosis at the early developmental stages of zebrafish.

甲基磺草脲 (SM) 是一种广泛使用的除草剂，因此会导致其在环境中的积累。SM 在模式生物中的毒性评估目前很少见。在本研究中，斑马鱼被用于评估 SM 对水生脊椎动物的不利影响。斑马鱼胚胎分别在受精后 5.5 至 72 小时 (hpf) 暴露于 0、10、20 和 40 毫克/升 SM。因此，SM 暴露导致 10、20 和 40 mg/L SM 处理组的斑马鱼幼虫的死亡率增加和孵化率降低。在 SM 暴露后以剂量依赖性方式观察到免疫细胞（中性粒细胞和巨噬细胞）数量减少。测量炎症反应（TLR4、MYD88、IL-1β、IL-6、IL-8、IFN-γ、IL-10 和 TGF-β）以估计免疫反应。抗炎因子（IL-10 和 TGF-β）在所有治疗组中均下调，并在 40 mg/L 暴露组发生显着变化。此外，行为测试表明，SM 处理显着增加了斑马鱼幼虫在明暗过渡期间的总距离、平均速度和最大加速度，随后的酶学测试显示出与运动行为相同的趋势。氧化应激中的含量显着增加，这反映在所有处理组的 ROS 水平上。细胞凋亡数在20、40 mg/L时显着增加，最高浓度组诱导p53、Bax/Bcl-2、caspase-9和caspase等凋亡相关基因显着增加（P < 0.001） -3. 总之，我们的结果表明，暴露于 SM 会导致发育毒性，