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Machanism of iron regulation on amnesic neurontoxin production by coastal diatoms

铁对沿海硅藻遗忘性神经毒素产生的调节机制

基本信息

批准号：
14560143
负责人：
TAKEDA Shigenobu
金额：
$ 2.69万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2003
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-14560143/
关键词：
Iron Domoic Acid Amnesic Shellfish Poisoning Diatom Pseudo-nitzschia Organic ligand Growth rate Iron limitation stress 記憶喪失性毒 Domoic acid 欠乏ストレス無菌株

项目摘要

Batch culture experiments were performed to investigate iron requirement for growth of a coastal diatom Pseudo-nitzschia multiseries, which id known to produce domoic acid, a causative toxin of amnestic shellfish poisoning. Specific growth rates of P.multiseries showed a 50% decrease when dissolved inorganic iron concentration [Fe'] in the media was about 0/1 nM. P.multiseriesi required relatively high dissolved inorganic iron concentration for the maximum growth, that is similar to the other coastal phytoplankton. However, P.multiseriesi was still able to grow at [Fe']<0.02 nM, which limit the growth of most coastal species completely. Under iron-stressed condition, specific growth rates of P.multiseriesi were not affected by the addition of 2μM domoic acid, suggesting domoic acid itself does stimulate iron transport to support high growth rates. When iron availability was greatly reduced by the addition of a fungal siderophore desferrioxamine B(DFB), growth rates of P.multiseriesi significantly increased. Even under these strict iron stressed conditions, domoic acid concentrations in the cells showed little change compared with control without DFB. In addition, domoic acid concentrations in the media were always below the detection limit. These findings suggest that P.multiseriesi may utilize organically complexed iron under severe iron limitation and this iron transport system becomes active without production or release of domoic acid. Such iron uptake mechanism may allow this species to grow at the extremely low iron conditions.

采用分批培养法研究了一种能产生软骨藻酸的多系拟菱形藻（Pseudo-nitzschia multiseries）生长对铁的需要量。当培养基中溶解的无机铁浓度[Fe ']约为0/1 nM时，多系假单胞菌的比生长率下降50%。多列原甲藻的最大生长需要相对较高的溶解无机铁浓度，这与其他沿海浮游植物相似。然而，P.multiseriesi仍然能够在[Fe ']<0.02 nM下生长，这完全限制了大多数沿海物种的生长。在铁胁迫条件下，添加2μM软骨藻酸对多列拟青霉的比生长速率没有影响，表明软骨藻酸本身确实刺激铁转运以支持高生长速率。当铁的有效性大大减少了真菌铁载体去铁胺B（DFB）的加入，P.multiseriesi的生长速度显着增加。即使在这些严格的铁应激条件下，与没有DFB的对照相比，细胞中软骨藻酸浓度也几乎没有变化。此外，培养基中软骨藻酸浓度始终低于检测限。这些结果表明，P.multiseriesi可能利用有机络合铁严重铁限制下，铁运输系统变得活跃，没有生产或释放软骨藻酸。这种铁吸收机制可能允许该物种在极低的铁条件下生长。