Effect of stress on heat shock protein levels, immune response and survival to fungal infection of Mamestra brassicae larvae.
Effect of stress on heat shock protein levels, immune response and survival to fungal infection of Mamestra brassicae larvae.
复制标题
DOI：
10.1016/j.jinsphys.2016.10.013
复制
发表时间：
2017
影响因子：
2.2
通讯作者：
E. H. Richards;M. Dani;Y. Lu;Tariq M. Butt;R. Weaver
中科院分区：
文献类型：
--
作者：
E. H. Richards;M. Dani;Y. Lu;Tariq M. Butt;R. Weaver
尽管利用真菌生物防治剂来杀死昆虫害虫是合乎需要的，但已知感染的结果可能受到许多标准的影响，包括目标昆虫是否受到胁迫。在目前的工作中，用球孢白僵菌的分生孢子局部处理鳞翅目害虫甘蓝夜蛾的幼虫，然后在48小时后进行热应激（HS; 37 °C持续1小时），导致与没有热应激（No-HS）的真菌处理的幼虫相似的幼虫存活水平。相比之下，当真菌处理后24小时应用HS时，幼虫存活率显着增加，表明HS可以保护幼虫免受B.巴西纳。相似地，暴露于HS的幼虫在真菌处理后48 h（而不是24 h）提供了对Metarhizium brunneum（V275）的保护。为了阐明HS诱导的幼虫抗真菌感染存活率增加的机制，评估了HS对关键细胞和体液免疫应答以及对选定热休克蛋白（HSP）水平的影响。当幼虫保持在控制（无HS）条件下，在24小时内，每毫升血淋巴的血细胞数没有显着差异。然而，与无HS对照相比，幼虫暴露于HS后立即（t = 0 h）和HS后4 h的血细胞密度显著增加，而在t = 24 h时恢复到对照水平。此外，体外试验表明，从幼虫收获的血细胞后立即（0小时）和4小时（但不是24小时）后，HS表现出较高的吞噬率的FITC标记的B。与从非HS幼虫收获的血细胞相比，有趣的是，HS似乎没有增加幼虫血浆中的抗真菌活性。用与果蝇HSP交叉反应的抗体进行Western印迹分析，结果表明，分别从50，000和100，000个血细胞提取物中得到了HSP 70和HSP 90的相对较强的信号，这些血细胞是从No-HS幼虫中收获的。相比之下，对于HSP 60，来自200，000个血细胞的裂解物导致相对弱的信号。当幼虫暴露于HS时，与HS后4 h和16 h的无HS对照相比，所有三种HSP的水平均增加。然而，治疗后24小时，任何热应激介导的HSP水平的增加是最小的，并没有一贯检测。当在从热应激和非热应激幼虫收获的脂肪体中评估HSP 90、70和60水平时，获得了类似的结果。关于HSP 27，即使处理来自200，000个血细胞或三倍量的脂肪体的裂解物也没有获得信号，这表明所用的抗HSP 27抗体不与M交叉反应。芸苔结果表明，HS介导的血细胞密度和吞噬活性的增加，以及HSP 90和70的上调，可能有助于增加M的存活。用B. bassiana和M. brunneum（V275）.
Although the utilisation of fungal biological control agents to kill insect pests is desirable, it is known that the outcome of infection may be influenced by a number of criteria, including whether or not the target insect is stressed. In the current work, topical treatment of larvae of the lepidopteran pest,Mamestra brassicae, with conidia ofBeauveria bassiana, followed by a heat stress (HS; 37 °C for 1 h) 48 h later, resulted in a similar level of larval survival to that occurring for no heat stress (No-HS), fungus-treated larvae. By contrast, when the HS was applied 24 h after fungal treatment, larval survival was significantly increased, indicating that the HS is protecting the larvae fromB. bassiana. Similarly, exposure of larvae to a HS provided protection againstMetarhizium brunneum(V275) at 48 h (but not 24 h) after fungal treatment.To elucidate the mechanism(s) that might contribute to HS-induced increases in larval survival against fungal infection, the effects of a HS on key cellular and humoral immune responses and on the level of selected heat shock proteins (HSP) were assessed. When larvae were kept under control (No HS) conditions, there was no significant difference in the haemocyte number per ml of haemolymph over a 24 h period. However, exposure of larvae to a HS, significantly increased the haemocyte density immediately after (t = 0 h) and 4 h after HS compared to the No HS controls, whilst it returned to control levels at t = 24 h. In addition,in vitroassays indicated that haemocytes harvested from larvae immediately after (0 h) and 4 h (but not 24 h) after a HS exhibited higher rates of phagocytosis of FITC-labelledB. bassianaconidia compared to haemocytes harvested from non-HS larvae. Interestingly, the HS did not appear to increase anti-fungal activity in larval plasma. Western blot analysis using antibodies which cross react withDrosophila melanogasterHSP, resulted in a relatively strong signal for HSP 70 and HSP 90 from extracts of 50,000 and 100,000 haemocytes, respectively, harvested from No-HS larvae. By contrast, for HSP 60, a lysate derived from 200,000 haemocytes resulted in a relatively weak signal. When larvae were exposed to a HS, the level of all three HSP increased compared to the No HS control 4 h and 16 h after the HS. However, 24 h after treatment, any heat stress-mediated increase in HSP levels was minimal and not consistently detected. Similar results were obtained when HSP 90, 70, and 60 levels were assessed in fat body harvested from heat stressed and non-heat stressed larvae. With regard to HSP 27, no signal was obtained even when a lysate from 200,000 haemocytes or three times the amount of fat body were processed, suggesting that the anti-HSP 27 antibody utilised does not cross-react with theM. brassicaeHSP. The results suggest that a HS-mediated increase in haemocyte density and phagocytic activity, together with an upregulation of HSP 90 and 70, may contribute to increasing the survival ofM. brassicaelarvae treated withB. bassianaandM. brunneum(V275).