脉冲磁场对趋磁螺细菌AMB-1磁小体形成及相关基因表达的影响

本文利用Cmag测量、透射电镜观察等技术研究了脉冲磁场对不同初始状态的趋磁螺细菌AMB-1(Magnetospirillum magneticum AMB-1)磁小体形成的影响,并对其相关蛋白MamA、Mms13、Mms6和MagA编码基因的表达情况做了荧光实时定量反转录聚合酶链式反应(qRT-PCR).结果表明:同自然地磁场相比,50Hz、1mT脉冲磁场可促进AMB-1磁小体形成;当初始菌种为含有磁小体的AMB-1时,脉冲磁场促进指数期菌体magA基因的表达;而当初始菌种为不含磁小体的AMB-1时,则促进指数期菌体magA和mamA基因的表达.脉冲磁场虽然导致指数期细胞磁颗粒不均匀,但使磁小体链加长,含磁小体菌的平均磁颗粒数也较地磁场明显增加.实验结果为应用磁场干预磁小体形成,提高磁小体产率的研究提供了实验和理论依据,也有助于进一步了解磁场的生物学效应.

Effect of pulse magnetic field on magnetosome formation and expression of mamA, mms13, mms6 and magA in Magnetospirillum sp.AMB-1 strain

To investigate the effect of pulse magnetic field (PMF) on magnetosome formation in Magnetospirillum sp. AMB-1 strain, a 50Hz, 1mT PMF was applied to cellular cultures. Magnetic and non-magnetic pre-cultures were prepared by controlling growth conditions and were inoculated into media and incubated under PMF or geomagnetic field. Magnetism of cells was measured by using a spectrophotometer coupled with applied magnetic fields and the values were described as Cmag. Magnetosome in cells was counted by transmission electron microscopy (TEM) observation. Comparing to geomagnetic field, PMF did not affect cellular growth, but seemed to enhance magnetosome formation. In addition, it appeared that the length of the magnetosome chain increased and the homogeneity of the magnetosome morphology decreased when PMF was applied to the cultures. The expression of mamA, mms13, mms6 and magA was analyzed by qRT-PCR. The PMF up-regulated the magA expression in the cultures inoculated with magnetic cells, and the magA and mamA expression in the cultures inoculated with non-magnetic cells. These are first examples showing the effect of the pulse magnetic field on bacterial gene expression.