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many found the ratio to be higher than unity (e.g.
[3,4]). Our results indicate that this ratio may also
be donor-specific, although in none of the cases
Fig. Ratios of total 2B-type to total 2A-type exchanges.
Exchanges observed after all doses of radiation (approximate
range – 0.2-2.8 Gy) were summed up.
were the deviations from unity strong enough to
be statistically significant. The mean ratio for all
chromosomes and donors was found to be close
to 1.
The results presented in this and the preceding
report indicate that inter-donor differences do
exist, however, not with respect to all chromosomes.
Our observations very well agree with the data published
by others in that chromosome 2 is less radiosensitive
than expected with minimal inter-donor
RADIOBIOLOGY
variability. Chromosome 14 is more sensitive than
expected and the sensitivity of chromosome 8 corresponds
to its DNA content, however, this trend
is individually variable. It appears that inter-donor
variability is an important factor in the radiosensitivity
of individual chromosomes and may
explain some of the controversies regarding the
inter-chromosomal distribution of radiation-induced
aberrations. The implication of this conclusion
for biological dosimetry is that the inter-donor
variability is a potential source of error in
calculating the dose absorbed by one individual on
the basis of a calibration curve generated with lymphocytes
of a different individual. This error can
be minimized by choosing chromosome 2 for analysis.
The work was supported by the Polish Ministry
of Scientific Research and Information Technology
– project No. 6 P05A 119 20.
References
[1]. Lloyd D.C., Lucas J.N., Edwards A.A., Deng W.,
Valente E., Hone P.A., Moquet J.E.: Radiat. Res., 155,
809-817 (2001).
[2]. Tucker J.D., Ramsey M.J., Lee D.A., Minkler J.L.:
Int. J. Radiat. Biol., 64, 27-37 (1993).
[3]. Schmid E., Zitzelsberger H., Braselmann H., Gray
J.W., Bauchinger M.: Int. J. Radiat. Biol., 62, 673-678
(1992).
[4]. Natarajan A.T., Vyas R.C., Darroudi F., Vermeulen
S.: Int. J. Radiat. Biol., 61, 199-203 (1992).
THE EFFECT OF TEMPERATURE ON THE FREQUENCY
OF RADIATION-INDUCED MICRONUCLEI
IN HUMAN PERIPHERAL BLOOD LYMPHOCYTES
Kinga Brzozowska, Andrzej Wójcik
The impact of temperature on the frequency of
radiation-induced chromosome aberrations in the
human lymphocytes was first described by Bajerska
and Liniecki [1]. We have performed experiments
to analyze the impact of blood temperature at irradiation
in vitro on the level of radiation-induced
micronuclei. Blood samples were drawn from two
healthy male donors aged 24 and 45 years and irradiated
at 0, 20 and 37 o C with X-rays (200 kVp, 5
mA, 3 mm Cu filter). The doses were: 0, 1 and 2
Gy for the first donor, and 0, 1.35 and 2.7 Gy for
the second donor. Twenty minutes before irradiation
as well as during irradiation, the blood samples
were incubated at 0, 20 or 37 o C. After irradiation,
blood samples (0.5 ml) were transferred into 4.5
ml RPMI 1640 medium supplemented with 25%
Fig. The dose-response curves for micronuclei (MN) in binucleated cells (BNC) in lymphocytes of the first (A) and
second (B) donor. * – the difference significant with p