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Trakia Journal of Sciences, Vol. 2, No. 3, 2004 36
Trakia Journal of Sciences, Vol. 2, No. 3, pp 36-39, 2004
Copyright © 2004 Trakia University
Available online at:
http://www.uni-sz.bg
ISSN 1312-1723
Original Contribution
GENETIC EFFECTS IN SOMATIC AND GERM CELLS IN RABBITS
FOLLOWING EXTERNAL GAMMA RADIATION.
I. RECIPROCAL TRANSLOCATIONS IN SPERMATOGONIA
P. Georgiev
1
, S. Tanchev
2
*, S. Georgieva
2
1
Department of Radiobiology and Radioecology, Faculty of Veterinary Medicine;
2
Department of Genetics, Breeding and Reproduction , Faculty of Agriculture,
Trakia University, 6000 Stara Zagora, Bulgaria
ABSTRACT
Male rabbits, aged 4.5 months, were subjected to graded total gamma irradiations of 0.5 Gy, 1.5 Gy,
2.5 Gy and 3.0 Gy with a dose density of 24 Gy/min. The genetic effects in spermatogonia were
assessed 3 months later using cytogenetic analysis of chromosomal preparations.
The data showed a dose-dependent increase in the frequency of reciprocal translocations, induced in
spermatogonia and detected in the spermatocyte stage in diakinesis metaphase I. The highest
frequency of reciprocal translocatins was observed in rabbits irradiated at 3.0 Gy. The dose-effect
function was linear from the type y=a+βD.
Key words: Gamma irradiation, spermatogenesis, translocations, stem cells.
INTRODUCTION
The classical method of biological dosimetry,
detection of radiation-induced chromosome
aberrations in peripheral blood lymphocytes,
gives only a general notion of the effect of
radiation on the gonad. The cytogenetic
analysis of lymphocytes is an indicatory
model, but could not be used as a model of the
potential risk for generations and populations
as a whole
The spermatogenesis in male
individuals is an exceptionally sensitive in
vivo system for biological dosimetry of
ionized radiation (1) because of the high
sensitivity of germ cells to radiation-induced
death and their sensitivity to induction of
mutations (2). The available literature data
show a considerable heterogeneity in the
radiosensitivity of the various cell types
during spermatogenesis. Despite the fact that
spermatids are considered to be among the
populations most susceptible to genetic
damage (3), spermatogonia are incontestably
the critical component because of their nature;
* Correspondence to: Assoc. Prof. Svetlin
Tanchev, Dept. of Genetics, Faculty of
Agriculture, Trakia University, 6000 Stara Zagora,
Bulgaria; Email: rector@uni-sz.bg
they are the precursors of the next generations
of developing and mature germ cells (4).
Up till now the test for detection of
translocations in diakinesis metaphase I is
used in the study on the mutagenic effect of
ionized radiations in mammals. This test
evaluates the frequency of induced
translocations in spermatogonia and predicts
the resulting genetic damage in F1 (5).
The knowledge of the fate of induced
translocations in spermatogonia is especially
important in the precise evaluation of genetic
risk. Genetically impaired spermatogonia
from meiosis form spermatozoa with non-
balanced, balanced or normal genome. This
situation could be responsible for the
appearance of dominant lethal mutations,
offspring with multiple abnormalities, as well
as phenotypically normal, heterozygous
translocations in the progeny (6, 7, 8, 9).
The present study aimed to detect the
frequency of reciprocal translocations in
spermatogonia of rabbits, irradiated with
graded doses of gamma rays in order to
determine the correlations between the dose
and the effect on the genetic makeup.
MATERIAL AND METHODS
The experiment was performed with sexually
mature 4.5-month old male New Zealand
rabbits. All animals were of equal body