地球上所有生物的繁衍生息和進(jìn)化都是在地磁場(chǎng)環(huán)境伴生中進(jìn)行的,。因此,,認(rèn)識(shí)地磁場(chǎng)對(duì)生物的影響是地球科學(xué)的重要研究?jī)?nèi)容。最近,,美國(guó)出版的《生物物理學(xué)雜志》(Biophysical Journal)和《地質(zhì)微生物學(xué)雜志》(Geomicrobiology Journal)雜志發(fā)表了中國(guó)科學(xué)院地質(zhì)與地球物理研究所地球深部結(jié)構(gòu)與過(guò)程研究室潘永信研究員與合作者在此研究領(lǐng)域的兩篇論文,他們綜合分子生物學(xué),、電子顯微鏡技術(shù),、巖石磁學(xué)等交叉學(xué)科手段,系統(tǒng)研究了趨磁細(xì)菌MYC-1的磁學(xué)性質(zhì)和趨磁游泳特性,。
研究表明,,趨磁球菌MYC-1屬于α-變形菌綱的一株新型趨磁細(xì)菌,它們?cè)诩?xì)胞內(nèi)合成1條磁小體鏈,,鏈的排列與細(xì)胞運(yùn)動(dòng)器官鞭毛具有一定的夾角;合成的磁小體為單疇磁鐵礦,。根據(jù)旋轉(zhuǎn)磁場(chǎng)游泳行為計(jì)算獲得單個(gè)細(xì)胞磁矩為1.8×10-15 Am2。他們發(fā)現(xiàn)無(wú)論是在直線場(chǎng)還是旋轉(zhuǎn)場(chǎng),,MYC-1均為螺旋前進(jìn),,而非直線運(yùn)動(dòng),,且隨磁場(chǎng)強(qiáng)度增加,,趨磁游泳速度(VM,,平行磁場(chǎng)方向)降低,,這項(xiàng)發(fā)現(xiàn)對(duì)趨磁細(xì)菌游泳速度隨外場(chǎng)強(qiáng)度增加而單調(diào)增加的傳統(tǒng)觀點(diǎn)提出了挑戰(zhàn),。研究結(jié)果反映出趨磁細(xì)菌與地磁場(chǎng)具有長(zhǎng)期協(xié)同進(jìn)化的特點(diǎn),當(dāng)磁場(chǎng)強(qiáng)度高于地磁場(chǎng)時(shí)趨磁游泳速度受到抑制,,這為揭示地磁場(chǎng)對(duì)生物的影響,、細(xì)菌礦化,以及認(rèn)識(shí)生物的趨磁性質(zhì)和磁導(dǎo)航具有重要科學(xué)意義,。(生物谷Bioon.com)
生物谷推薦原始出處:
Biophysical Journal Volume 97 August 2009 986–991
Reduced efficiency of magnetotaxis in magnetotactic coccoid bacteria in higher than geomagnetic fields.
Pan Y, Lin W, Li J, Wu W, Tian L, Deng C, Liu Q, Zhu R, Winklhofer M, and Petersen N
Magnetotactic bacteria are microorganisms that orient and migrate along magnetic field lines. The classical model of polar magnetotaxis predicts that the field-parallel migration velocity of magnetotactic bacteria increases monotonically with the strength of an applied magnetic field. We here test this model experimentally on magnetotactic coccoid bacteria that swim along helical trajectories. It turns out that the contribution of the field-parallel migration velocity decreases with increasing field strength from 0.1 to 1.5 mT. This unexpected observation can be explained and reproduced in a mathematical model under the assumption that the magnetosome chain is inclined with respect to the flagellar propulsion axis. The magnetic disadvantage, however, becomes apparent only in stronger than geomagnetic fields, which suggests that magnetotaxis is optimized under geomagnetic field conditions. It is therefore not beneficial for these bacteria to increase their intracellular magnetic dipole moment beyond the value needed to overcome Brownian motion in geomagnetic field conditions.