Peuthert Anja, Lawton Linda, Pflugmacher Stephan
Leibniz Institute of Freshwater Ecology and Inland Fisheries, RG Biochemical Regulation, Müggelseedamm 301, 12587 Berlin, Germany.
Toxicon. 2008 Jul;52(1):84-90. doi: 10.1016/j.toxicon.2008.04.172. Epub 2008 May 29.
Irrigation of crop plants with surface water can be a threat if cyanobacterial toxins are present in the water. Cyanotoxins are known to cause adverse effects in plants. Microcystin (MC), a cyclic heptapeptide, with more than 70 structural variants, is a frequently occurring toxin. MC is a specific inhibitor of serine/threonine protein phosphatases 1 and 2A (PP1 and 2A), important regulatory enzymes in eukaryotic cells. Protein phosphatases consist of a catalytic subunit and one or more regulatory subunits. In Alfalfa several isoforms of the catalytic subunit of PP1 (MsPP1alpha, MsPP1beta, MsPP1gamma, MsPP1delta, MsPP1varepsilon) and PP2A (MsPP2A Calpha/beta/gamma) are known along with isoforms of the regulatory subunits of PP2A (MsPP2A Aalpha/beta, MsPP2A Balpha/beta). The in vivo effect of environmentally relevant concentrations of cyanobacterial components on the mRNA transcript level of the subunits of protein phosphatases 1 and 2A in Alfalfa (Medicago sativa) was examined using semi-quantitative RT-PCR. Plants were exposed for one week to 5 microg L(-1) microcystin-LR, microcystin-LW, okadaic acid and to cell-free cyanobacterial crude extracts from Microcystis aeruginosa containing 5 microg L(-1) microcystin-LR and a toxin-free crude extract from Synechocystis spp. The protein phosphatase activity in vivo was inhibited when exposed to toxins and crude extract containing microcystin-LR, no change was induced by Synechocystis crude extract. The gene expression of the MsPP1gamma subunit and the MsPP1varepsilon subunit was induced in plants exposed to MC-LW.
如果地表水中存在蓝藻毒素，用其灌溉农作物可能构成威胁。已知蓝藻毒素会对植物产生不利影响。微囊藻毒素（MC）是一种环状七肽，有70多种结构变体，是一种常见毒素。MC是丝氨酸/苏氨酸蛋白磷酸酶1和2A（PP1和2A）的特异性抑制剂，这两种酶是真核细胞中的重要调节酶。蛋白磷酸酶由一个催化亚基和一个或多个调节亚基组成。在苜蓿中，已知PP1（MsPP1alpha、MsPP1beta、MsPP1gamma、MsPP1delta、MsPP1varepsilon）和PP2A（MsPP2A Calpha/beta/gamma）催化亚基的几种同工型以及PP2A调节亚基的同工型（MsPP2A Aalpha/beta、MsPP2A Balpha/beta）。使用半定量RT-PCR检测了环境相关浓度的蓝藻成分对苜蓿（紫花苜蓿）中蛋白磷酸酶1和2A亚基mRNA转录水平的体内影响。将植物暴露于5μg L(-1) 的微囊藻毒素-LR、微囊藻毒素-LW、冈田酸以及含有5μg L(-1) 微囊藻毒素-LR的铜绿微囊藻无细胞蓝藻粗提物和集胞藻属的无毒粗提物中一周。当暴露于毒素和含有微囊藻毒素-LR的粗提物时，体内蛋白磷酸酶活性受到抑制，集胞藻粗提物未诱导变化。在暴露于MC-LW的植物中，MsPP1gamma亚基和MsPP1varepsilon亚基的基因表达被诱导。
