XIX Sympozjum Srodowiskowe PTZE - materialy.pdf

2.2 IF-MFs exposure devices
XIX Sympozjum PTZE, Worliny 2009
Two exposure systems used in this study. An IF-MFs exposure device (Fig. 1), which has
a resin CO2 incubator (inside dimension of 200mm x 200mm x 200mm, water-jacket for
temperature control) mounted over a plain coil (diameter of 160mm) was used. Plain coil was
driven by bi-polar amplifier (BP4620, NF block, Japan). Sinusoidal IF-MFs were generated
using this device and maximum density of magnetic field within exposure area was up to
0.8 mT at 2 kHz, 10 kHz and 20 kHz, respectively. Another exposure system was to generate
0.91 mT rms at 2 kHz, 1.1 mT
rms at 20 kHz, respectively [1].
2.3 Experimental procedure
For Ames test, cultured
bacterial cells were poured on
minimal glucose agar plates
with a trace of histidine and
biotin. These test plates
divided into two groups and
one group was incubated
under IF-MF (2 and 20 kHz)
Fig. 1 IF-MFs exposure device
and the other group was incubated without IF-MF as control. After 48 hours, revertant
colonies were scored.
For MLA, cells were inoculated in a T-25 flask filled with 5 ml of RPMI1640 medium with
10% horse serum (2.5x10 5 cells/ml) and were exposed to a IF-MF (2, 10 and 20 kHz) for
48 hr in 5% CO2 at 37 o C with single dilution after 24 hr. Unexposed control cells were
incubated in a conventional incubator. After exposure period, plate efficiency and frequency
of TFT resistant cells as tk -/- mutant was determined.
For in vitro micronucleous test, The Chinese hamster V79 cells were exposed to a IF-MF
(2, 10 and 20 kHz) for 24h in 35mm Petri dishes. After the exposure, cells were treated with
cytochalasin B. Then cells were fixed 24h later after the cytochalasin B treatment. The ratios
of micronucleus formation rates were estimated by counting micronucleus in approximately
1,000 binucleous cells.
3. Results and Discussion
In Ames test, no statistically significant
difference in mutation frequency was
observed between exposed and control
groups in both TA98 and TA100 strain.
In the MLA, the plate efficiency that is
representative index of acute toxicity was not
affected by exposure to all IF-MFs
conditions. In addition, the mutation
frequency at tk allele (tk +/- to tk -/- ) is almost same between an IF-MF exposed and unexposed
cells in all IF-MFs exposure conditions. Fig. 2 shows mutation frequency by exposure to
62
Mutation Frequency (×10-6 Mutation Frequency (×10 cells) -6 cells)
C ontrol Exposure MMS
1000
900
800
700
*
600
500
400
300
200
100
0
Treatm ent
Fig. 2 Mutation frequency by exposure to 0.8 mT,
20 kHz IF MF.