Pavlichenko Vasiliy V, Protopopova Marina V, Timofeyev Maxim, Luckenbach Till
Siberian Institute of Plant Physiology and Biochemistry, Siberian Branch of Russian Academy of Sciences (SIPPB SB RAS), Lermontov Str. 132, 664033, Irkutsk, Russia.
Environ Sci Pollut Res Int. 2015 Apr;22(7):5453-68. doi: 10.1007/s11356-014-3758-y. Epub 2014 Nov 5.
The fauna of Lake Baikal in Eastern Siberia, the largest freshwater body on Earth, is characterized by high degrees of biodiversity and endemism. Amphipods, a prominent taxon within the indigenous fauna, occur in an exceptionally high number of endemic species. Considering the specific water chemistry of Lake Baikal with extremely low levels of potentially toxic natural organic compounds, it seems conceivable that certain adaptions to adverse environmental factors are missing in endemic species, such as cellular defense mechanisms mitigating toxic effects of chemicals. The degree to which the endemic fauna is affected by the recently occurring anthropogenic water pollution of Lake Baikal may depend on the existence of such cellular defense mechanisms in those species. We here show that endemic amphipods express transcripts for Abcb1, a major component of the cellular multixenobiotic resistance (MXR) defense against toxic chemicals. Based on a partial abcb1 cDNA sequence from Gammarus lacustris, an amphipod species common across Northern Eurasia but only rarely found in Lake Baikal, respective homologous sequences were cloned from five amphipods endemic to Lake Baikal, Eulimnogammarus verrucosus, E. vittatus, E. cyaneus, E. marituji, and Gmelinoides fasciatus, confirming that abcb1 is transcribed in those species. The effects of thermal (25 °C) and chemical stress (1-2 mg L(-1) phenanthrene) in short-term exposures (up to 24 h) on transcript levels of abcb1 and heat shock protein 70 (hsp70), used as a proxy for cellular stress in the experiments, were exemplarily examined in E. verrucosus, E. cyaneus, and Gammarus lacustris. Whereas increases of abcb1 transcripts upon treatments occurred only in the Baikalian species E. verrucosus and E. cyaneus but not in Gammarus lacustris, changes of hsp70 transcript levels were seen in all three species. At least for species endemic to Lake Baikal, the data thus indicate that regulation of the identified amphipod abcb1 is triggered within the general cellular stress response. This is the first report presenting molecular data on a MXR transporter in amphipods, an ecotoxicologically important but with regard to gene sequence data comparatively little explored taxon.
位于西伯利亚东部的贝加尔湖是地球上最大的淡水水体，其动物区系具有高度的生物多样性和特有性。在本地动物区系中占显著地位的端足类动物，有数量异常众多的特有物种。考虑到贝加尔湖特定的水化学性质，其中潜在有毒天然有机化合物的含量极低，那么可以想象，特有物种可能缺乏对不利环境因素的某些适应性，比如减轻化学物质毒性作用的细胞防御机制。特有动物区系受贝加尔湖近期人为水污染影响的程度，可能取决于这些物种中是否存在此类细胞防御机制。我们在此表明，特有端足类动物表达了Abcb1的转录本，Abcb1是细胞对多种有毒化学物质抗性（MXR）防御的主要组成部分。基于来自欧亚大陆北部常见但在贝加尔湖很少见的一种端足类动物——湖沼钩虾（Gammarus lacustris）的部分abcb1 cDNA序列，从贝加尔湖特有的五种端足类动物——疣背真钩虾（Eulimnogammarus verrucosus）、带纹真钩虾（E. vittatus）、蓝真钩虾（E. cyaneus）、滨真钩虾（E. marituji）和带纹似钩虾（Gmelinoides fasciatus）中克隆了各自的同源序列，证实这些物种中abcb1可转录。在疣背真钩虾、蓝真钩虾和湖沼钩虾中，以热应激（25℃）和化学应激（1 - 2 mg L⁻¹菲）进行短期暴露（最长24小时），以此作为实验中细胞应激的指标，对abcb1和热休克蛋白70（hsp70）转录水平的影响进行了示例性研究。处理后abcb1转录本增加的情况仅出现在贝加尔湖特有物种疣背真钩虾和蓝真钩虾中，而湖沼钩虾中未出现，所有三个物种中hsp70转录水平均有变化。因此，至少对于贝加尔湖特有物种而言，这些数据表明所鉴定的端足类动物abcb1的调控是在一般细胞应激反应中触发的。这是首次报道端足类动物中一种MXR转运蛋白的分子数据，端足类动物在生态毒理学方面很重要，但就基因序列数据而言，是一个相对较少被研究的分类群。
