Effects of Hypomagnetic Field on Magnetosome Formation of Magnetospirillum Magneticum AMB-1
Effects of Hypomagnetic Field on Magnetosome Formation of Magnetospirillum Magneticum AMB-1
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DOI：
10.1080/01490450802258295
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发表时间：
2008-07
影响因子：
2.3
通讯作者：
Xiao K. Wang;Q. Ma;Wei Jiang;Jing Lv;Weidong Pan;Ta Song;Long-Fei Wu
中科院分区：
文献类型：
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作者：
Xiao K. Wang;Q. Ma;Wei Jiang;Jing Lv;Weidong Pan;Ta Song;Long-Fei Wu
趋磁细菌合成细胞内的磁性颗粒，磁小体，排列成链，并赋予细胞一个磁偶极矩。为探讨地磁场对趋磁细菌的作用，研究了弱磁场对磁性细菌AMB-1中磁小体形成的影响。细胞在专门设计的装置中培养，其中地磁场降低约100倍至小于500 nT。AMB-1培养物在低磁场或地磁场中孵育。结果表明，弱磁场对细菌的平均磁粒数和细菌铁耗量无显著影响。但在稳定期的细胞生长（OD）低于在地磁场中培养的细菌，而在指数生长期的细胞磁性（Rmag）高于在地磁场中培养的细菌。透射电镜（TEM）图像统计结果显示，低磁场组AMB-1细胞内磁性颗粒的平均粒径大于地磁场组，且低磁场培养16 h后，大粒径（>50 nm）磁性颗粒所占比例更大。进一步研究了亚磁场对AMB-1细胞基因表达的影响。定量RT-PCR结果显示，弱磁场对mms 13表达上调，对mms 6表达下调，对magA表达无影响。结果表明，弱磁场对AMB-1细胞稳定期的生长、磁小体的结晶过程以及mms 13、mms 6的表达均有影响。此外，我们的研究结果表明，地磁场在磁小体的生物矿化中起着重要的作用。
Magnetotactic bacteria synthesize intracellular magnetic particles, magnetosomes, which arrange in chain(s) and confer on cell a magnetic dipolar moment. To explore the function of geomagnetic field to magnetotactic bacteria, the effects of hypomagnetic field on magnetosome formation in Magnetospirillum magneticum AMB-1 were studied. Cells were cultivated in a specially designed device where geomagnetic field was reduced by about 100-fold to less than 500nT. AMB-1 cultures were incubated in hypomagnetic field or geomagnetic field. Results showed that hypomagnetic field had no significant effects on the average number of magnetic particles per bacterium and bacterial iron depletion. However, the growth (OD) of cell at stationary-phase was lower and cellular magnetism (R mag) at exponential growth phase was higher than that of bacteria cultivated in geomagnetic field. Statistic results on transmission electron microscopy (TEM) micrographs showed that the average size of magnetic particles in AMB-1 cells in hypomagnetic field group was larger than that of in geomagnetic field group and more ratio of larger-size magnetic particles (>50 nm) was observed when cultivated 16 h under hypomagnetic field. Furthermore, the influences of hypomagnetic field on gene expression were studied in AMB-1 cells. Quantitative RT-PCR results showed that hypomagnetic field up-regulated mms13, down-regulated mms6 and had no effect on magA. Together, the results showed that hypomagnetic field could affect the growth of AMB-1 at the stationary-phase, the crystallization process of magnetosomes, and mms13, mms6 expressions. In addition, our results suggested that the geomagnetic field plays an important role in the biomineralization of magnetosomes.