Medical/biological study (experimental study)

Effects of pulsed magnetic field on the formation of magnetosomes in the Magnetospirillum sp. strain AMB-1 med./bio.

By: Pan W, Chen C, Wang X, Ma Q, Jiang W, Lv J, Wu LF, Song T

Published in: Bioelectromagnetics 2010; 31 (3): 246-251

Aim of study (acc. to author)

To study the effects of a 50 Hz, 2 mT pulsed magnetic field on the formation of magnetosomes in Magnetospirillum sp. strain AMB-1.

Background/further details

Magnetotactic bacteria are a diverse group of microorganisms which possess one or more chains of magnetosomes (containing magnetite). These bacteria are able to use the geomagnetic field for direction sensing, thus providing a simple model for the study of magnetite-based magnetoreception.
56 bacterial samples were tested (28 were exposed and 28 samples were sham-exposed).

Endpoint

molecular biosynthesis: formation of magnetosomes in Magnetospirillum spec.
cell viability/cell division/proliferation: gowth of bacteria

Exposure

- 50/60 Hz
- magnetic field
- signals/pulses

Exposure	Parameters
Exposure 1: 50 Hz Modulation type: pulsed Exposure duration: continuous for 2 h, 4 h, 8 h, 12 h, 16 h or 24 h	magnetic flux density: 2 mT maximum (at the center of the solenoid)

Exposure 1

Main characteristics

Frequency	50 Hz
Type	magnetic field
Exposure duration	continuous for 2 h, 4 h, 8 h, 12 h, 16 h or 24 h

Modulation

Modulation type	pulsed
Duty cycle	50 %
Pulse type	rectangular

Exposure setup

Exposure source	solenoid
Setup	400 mm long solenoid coil with a diamter of 200 mm; samples placed inside the solenoid
Sham exposure	A sham exposure was conducted.

Parameters

Measurand	Value	Type	Method	Mass	Remarks
magnetic flux density	2 mT	maximum	measured	-	at the center of the solenoid

Exposed system:

bacterium
Magnetospirillum spec./AMB-1

Methods Endpoint/measurement parameters/methodology

molecular biosynthesis: formation of magnetosomes/number of magnetic particles and particle size (transmission electron microscopy); iron accumulation in the bacterial cells (atomic absorption spectrophotometry)
cell function: cellular magnetism
cell viability/cell division/proliferation: formation of magnetosomes gowth of bacteria (optical density)
morphol./histopathol. changes: bacterial morphology (transmission electron microscopy)

Investigated system:

Time of investigation:

during exposure
after exposure

Main outcome of study (acc. to author)

The data showed that the cellular magnetism of the bacterial culture significantly increased while the growth of cells remained unaffected after exposure. After exposure, the number of magnetic particles per cell was increased by about 15% and slightly enhanced ratios of magnetic particles of superparamagnetic property (size <20 nm) and mature magnetosomes (size >50 nm) were found. In addition, the intracellular iron accumulation slightly increased after pulsed magnetic field exposure.
The authors conclude that 50 Hz, 2 mT pulsed magnetic field exposure affect the formation of magnetosomes in Magnetospirillum sp. strain AMB-1. The pulsed magnetic field could increase cellular magnetism and the number of magnetic particles and affected the distribution of magnetosomes.

Study character:

medical/biological study
experimental study
full/main study
Brief Communication

Study funded by

Human Frontier Science Program (HFSP), Strasbourg, France
National Natural Science Foundation (NSFC), China

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