Mesjasz-Przybyłowicz Jolanta, Orłowska Elżbieta, Augustyniak Maria, Nakonieczny Mirosław, Tarnawska Monika, Przybyłowicz Wojciech, Migula Paweł
Materials Research Department, iThemba LABS, National Research Foundation, P.O. Box 722, Somerset West 7129, South Africa.
Materials Research Department, iThemba LABS, National Research Foundation, P.O. Box 722, Somerset West 7129, South Africa Department of Molecular Biology and Genetics, University of Aarhus, Gustav Wieds Vej 10 C, Aarhus C 8000, Denmark.
J Insect Sci. 2014 Jan 1;14:152. doi: 10.1093/jisesa/ieu014. Print 2014.
The phenomenon of metal hyperaccumulation by plants is often explained by a pathogen or herbivore defense hypothesis. However, some insects feeding on metal hyperaccumulating plants are adapted to the high level of metals in plant tissues. Former studies on species that feed on the leaves of Berkheya coddii Roessler 1958 (Asteraceae), a nickel-hyperaccumulating plant, demonstrated several protective mechanisms involved in internal distribution, immobilization, and elimination of Ni from the midgut and Malpighian tubules. These species are mainly coleopterans, including the lady beetle, Epilachna nylanderi (Mulsant 1850) (Coleoptera: Coccinellidae), collected from the ultramafic ecosystem near Barberton in South Africa. By performing particle-induced X-ray emission microanalysis elemental microanalysis (PIXE), this study examined whether Ni may be harmful to internal body systems that decide on insect reactivity (central nervous system [CNS]), their reproduction, and the relationships between Ni and other micronutrients. Data on elemental distribution of nine selected elements in target organs of E. nylanderi were compared with the existing data for other insect species adapted to the excess of metals. Micro-PIXE maps of seven regions of the CNS showed Ni mainly in the neural connectives, while cerebral ganglia were better protected. Concentrations of other bivalent metals were lower than those of Ni. Testis, compared with other reproductive organs, showed low amounts of Ni. Zn was effectively regulated at physiological dietary levels. In insects exposed to excess dietary Zn, it was also accumulated in the reproductive organs. Comparison of E. nylanderii with other insects that ingest hyperaccumulating plants, especially chrysomelid Chrysolina clathrata (Clark) (Coleoptera: Chrysomelidae), showed lower protection of the CNS and reproductive organs.
植物对金属的超积累现象通常用病原体或食草动物防御假说来解释。然而，一些以金属超积累植物为食的昆虫适应了植物组织中高水平的金属。以前对以1958年的伯克西亚柯迪（菊科）（一种镍超积累植物）叶片为食的物种的研究表明，有几种保护机制涉及镍在中肠和马氏管中的内部分布、固定和消除。这些物种主要是鞘翅目昆虫，包括从南非巴伯顿附近的超镁铁质生态系统中采集的瓢虫，尼氏食植瓢虫（1850年穆尔桑特）（鞘翅目：瓢虫科）。通过进行粒子诱导X射线发射微分析元素微分析（PIXE），本研究检查了镍是否可能对决定昆虫反应性的内部身体系统（中枢神经系统 [CNS]）、它们的繁殖以及镍与其他微量营养素之间的关系有害。将尼氏食植瓢虫目标器官中九种选定元素的元素分布数据与其他适应金属过量的昆虫物种的现有数据进行了比较。中枢神经系统七个区域的微PIXE图谱显示镍主要存在于神经连接中，而脑神经节受到更好的保护。其他二价金属的浓度低于镍。与其他生殖器官相比，睾丸中的镍含量较低。锌在生理饮食水平下得到有效调节。在暴露于过量饮食锌的昆虫中，锌也会在生殖器官中积累。将尼氏食植瓢虫与其他摄取超积累植物的昆虫，特别是叶甲科的网纹叶甲（克拉克）（鞘翅目：叶甲科）进行比较，发现中枢神经系统和生殖器官的保护作用较低。
