以IIS通路为中心的Zn2+胁迫对黑水虻幼虫生长影响的氧化应激机制研究

As one of the most important resource insects, the larvae of black soldier fly Hermetia illucens L. could degrade many organic wastes such as manure, and are rich in protein and fat. Currently, they gradually become the main way to manage the manure and were used as valuable alternative protein. However, the larval growth and their security as biological resource were also challenged with the increasing heavy metals accumulated in the manure. In our previous studies, it was found that their growth and antioxidant capacity were promoted after low levels of zinc stress, while inhibited after high levels of zinc exposure. And the expression levels of FOXO, one of the signaling molecular in the insulin/IGF-like signaling pathway were also changed. Therefore, we inferred that the reactive oxygen species induced by zinc exposure in the larvae might interact with insulin/IGF-like signal pathway and its relative pathways to modulate the growth of larvae. To verify this hypothesis, the levels of reactive oxygen species in the 5th instar larvae stressed by different concentrations of zinc for one and three generations, and the effects of zinc exposure on the metabolite in the hemolymph were detected. Then, the insulin/IGF-like signaling pathway and MAPK signaling pathway, and their cross-talk with reactive oxygen species were also investigated to elucidate the redox mechanism of the effects of zinc stress on the growth of H. illucens larvae. We hope that these results could provide theoretical support for the security of H. illucens as an alternative biological resource and proteins in the future.

黑水虻是重要的资源昆虫，其幼虫可降解粪便等有机废弃物，且含有丰富的蛋白质和脂类，日渐成为粪便管理和替代性蛋白质产生的主要方式。然而，粪便中逐年递增的重金属也对其生长和作为生物资源的安全性产生了影响。在我们前期研究中发现，低浓度重金属Zn2+促进而高浓度Zn2+抑制了黑水虻幼虫的生长和抗氧化能力，且影响了IIS通路信号分子FOXO的表达量。我们推测Zn2+诱导黑水虻幼虫产生了活性氧，并与IIS通路及相关通路协同作用调节幼虫的生长。为证实这一推测，本课题以第1、3代受不同浓度Zn2+胁迫的黑水虻5龄幼虫为研究对象，在明确对照和各处理虫体中活性氧水平的基础上，探讨Zn2+胁迫幼虫血淋巴代谢产物的影响，并结合Zn2+胁迫对IIS与MAPK通路信号分子交叉反应的结果及与ROS的关联，阐明Zn2+胁迫对黑水虻幼虫生长影响的氧化应激机制，以为黑水虻作为替代蛋白质和生物资源的安全性提供一定依据。

黑水虻是重要的资源昆虫，其幼虫可降解粪便等有机废弃物，且含有丰富的蛋白质和脂类，日渐成为粪便管理和替代性蛋白质产生的主要方式。然而，粪便中逐年递增的重金属也对其生长和作为生物资源的安全性产生了影响。我们推测，Zn2+诱导黑水虻幼虫产生了ROS，并通过与IIS等通路的作用调节幼虫的生长。因此，本课题以第1、3代受不同浓度Zn2+胁迫的黑水虻5龄幼虫为研究对象，在明确各处理虫体中ROS水平的基础上，探讨Zn2+胁迫幼虫血淋巴代谢产物的影响，并结合Zn2+胁迫对IIS/MAPK通路信号分子交叉反应的结果及与ROS的关联，阐明Zn2+胁迫对其生长影响的氧化应激机制。结果表明， Zn2+的胁迫剂量依赖性的增加了黑水虻幼虫体内和头部ROS水平，且受75、300和1200 mg/kg Zn2+胁迫幼虫分别采用调节糖、脂和蛋白代谢的方式应对Zn2+胁迫。同时，幼虫通过激活头部p38 MAPK、抑制PI3K/AKT mRNA水平，对低、中剂量Zn2+一代的胁迫做出响应；而3代低、中剂量Zn2+的胁迫增加了MAPK/IIS通路关键信号分子的表达水平；但在高剂量Zn2+胁迫下，第1、3代MAPK/IIS通路关键信号分子的表达水平均有所增加。而低剂量Zn2+胁迫1、3代幼虫脂肪体内MAPK/IIS通路信号分子的变化趋势与头部类似。血淋巴中p38 MAPK/ PI3K/AKT mRNA 的表达水平在各剂量Zn2+胁迫下均有所增高。经1% NAC处理后，不同组织内MAPK/IIS通路中增高或降低的信号分子的相对表达水平均有不同程度的缓解，且低浓度 Zn2+增强，而高浓度Zn2+减缓幼虫发育的趋势也有减缓，表明低剂量Zn2+处理产生的ROS可在一定程度上增强、而中、高剂量产生的ROS对损伤了幼虫的发育，MAPK/IIS信号通路参与了此调节过程。研究结果为黑水虻作为替代蛋白质的安全性提供一定依据。