BAR4 Page 1
© PENSOFT
Publishers
BulgarianHAntarctic
AND MICROBIAL ABUNDANCE OF MOSS AND COASTAL
ABITATS ...Research
SOIL CHARACTERISTICS
1
Sofia – Moscow
Life Sciences, vol. 4: 1-8, 2004
Chromosomal Instability of Winterers Before and
After Antarctic Expeditions.
KATERYNA AFANASIEVA, STANISLAV RUSHKOVSKY, VLADIMIR BEZRUKOV.
Department of General and Molecular Genetics, Kyiv Taras Shevchenko National University, 64 Volodymyrska Street, Kyiv, 01033, Ukraine ([email protected])
SUMMARY
An estimation of parameters of chromosomal instability in human lymphocytes of
winterers before and after some Ukrainian Antarctic expeditions (VI - VIII UAE) was
carried out. The level of structural chromosome aberrations (metaphases with chromosome aberrations and chromosome aberration) and end-points of chromosomal segregation failure (metaphases with premature centromere division, premature centromere division, total premature centromere division, polyploid mitosis) were selected as parameters of
chromosomal instability. The significant increase of the levels of metaphases with chromosome aberrations and chromosome aberration after the expeditions indicates the presence
of damaging factors in Antarctica. The end-points of chromosomal segregation failure
reflected features of groups of winterers and environmental conditions for each expedition.
Key words: chromosomal instability, chromosome aberrations, chromosomal segregation failure, lymphocytes, Ukrainian Antarctic expeditions, winterers
INTRODUCTION
The environmental impact on the genome of different native Antarctic species is
one of the priority studies carried out in Antarctica. These species have lived in Antarctic conditions for millions of years and they are adapted to such an environment.
In contrast to native species, these conditions are not ordinary for the human organism, which must adapt to such extreme conditions. The adaptation implies changes in
the functioning of all the organs and the physiological system of the organism, including the genome (DECAMPS, 2004). Thus the influence of Antarctic factors
should be studied for people living (having lived) in Antarctica for a long time.
BAR4 Page 2
2
A. KENAROVA, V. BOGOEV
The main investigations in this area were carried out for some medical and physiological indexes. But there is no research describing the consequences of the influence of Antarctic conditions on the human genome. These studies must determine a
presence of any genotoxic factor, its nature and mechanism of action as do all conventional studies in the field of genetic toxicology (ALBERTINI, 2000).
The analysis of chromosomal anomalies in human peripheral blood lymphocytes
is a universally recognized method for the estimation of the influence of different
factors on the human genome (TAWN, 1991). This assay allows the evaluation of the
damaging factors according to the level and spectrum of numerical and qualitative
chromosomal aberrations.
This article offers a comparative analysis of the level and spectrum of chromosomal instability of Ukrainian overwinterers before and after wintering in Antarctica.
MATERIALS AND METHODS
Blood samples for chromosome assays were obtained from the group of candidates (33 healthy men) for VI - VIII UAE during medical examinations before and
after expeditions. Blood was collected by venepuncture. Samples of whole blood (1
ml) were cultivated in 5 ml of IMDM medium. PHA-P (“GENOME”, Donetsk) 5 mg per 1 ml of medium was used for blast-transformation of lymphocytes. Cultures were incubated at 37 °C for 52 h.
Colchicine (1 mg/ml, final concentration) was added 1.5 – 2 hours before the end
of cultivation. After that cultivation cells were treated with 0.075 M KCl and fixed in
a methanol:acetic acid (3:1) mixture. Metaphase plates were prepared by dropping
cell suspension onto cool moist slides. Slides were stained by the routine Giemsa
technique according to the standard procedure (TAWN, 1991).
The level of structural chromosome aberrations (metaphases with chromosome
aberrations and chromosome aberration) and end-points of chromosomal segregation failure (metaphases with premature centromere division, premature centromere
division, total premature centromere division, polyploid mitosis) were selected as
parameters of chromosomal instability.
RESULTS AND DISCUSSION
Structural chromosome aberrations
The average level of metaphases with chromosome aberrations (AM) was
2.25±0.37 % before and 3.01±0.30 % after expeditions. The average rate of chromosome aberration (ChA) was and 2.44±0.41 % before and 3.20±0.34 % after
BAR4 Page 3
SOIL CHARACTERISTICS AND MICROBIAL ABUNDANCE OF MOSS AND COASTAL HABITATS ...
3
expeditions (Figure 1). The values of ChA and AM did not differ significantly (we
found only a few metaphases with more than one aberrations). The differences in the
levels of investigated end-points of chromosomal instability before and after expeditions were statistically significant. A strong tendency to an increase in the chromosomal aberration frequency was observed for each expedition. This result implies an
existence of some Antarctic factors that can induce chromosomal aberrations in human lymphocytes.
Figure 1. The levels of metaphases with chromosome aberrations and chromosome aberration
before and after expeditions
It is well known that chemical mutagens induce chromosome aberrations of the
chromatid type while ionizing radiation induces the aberrations of the chromosomal
type (HSU, 1996). Thus, an analysis of the aberration spectrum allows one to determine the possible nature of the main damaging factor. The predominant contribution in this spectrum was from aberrations of the chromatid type both before and
after expeditions. Any alteration of the chromatid to chromosomal aberration types
of ratio was not observed after expeditions (Figure 2).
Hence, a more detailed analysis of the spectrum was carried out. In general, the
spectrum of aberrations was similar both before and after expeditions. The prevalent
chromosome aberration was chromatid breaks. The markers of radiation impact
(dicentric chromosomes and centric rings) occurred in a few cases (Figure 3). The
analysis of the spectrum changes indicates that neither chemical mutagens nor physical mutagens can be considered as essentially more important damaging factors in
BAR4 Page 4
4
A. KENAROVA, V. BOGOEV
Figure 2. Chromatid to chromosomal aberration types before and after expeditions
Antarctica in comparison with Ukraine. However, growth of AM and ChA was
observed after expeditions. This increase may be explained by the presence of nonspecific factors which influence the human genome. Such factors may include longterm isolation, inversion of seasons, achromatization, desynchronoze and other factors called “stress-factors”.
Figure 3. Detailed spectrum of chromosome aberrations before and after expeditions. SF –
single fragments, AE – chromatid asymmetrical exchanges, SE – chromatid symmetrical exchanges,
DF – double fragments, D – dicentric chromosomes, AR – acentric rings, CR – centric rings,
T+I – translocations and invertions.
BAR4 Page 5
SOIL CHARACTERISTICS AND MICROBIAL ABUNDANCE OF MOSS AND COASTAL HABITATS ...
5
End-points of chromosomal segregation failure
Some mutagenic factors can damage the genome through a disruption of normal
chromosomes segregation during mitosis. The major end-points of such influence
are metaphases with premature centromere division (MPCD), premature centromere
division (PCD), total premature centromere division (TPCD), polyploid mitosis (PM)
(PARRY, 2002).
The average rates of these parameters are shown in Table 1.
Table 1. The average rates of end-points of chromosomal segregation failure.
Before expeditions
After expeditions
MPCD, %
PCD, %
TPCD, %
PM, ‰
0.96±0.15
0.89±0.17
1.76±0.39
1.33±0.30
0.33±0.09
0.39±0.06
0.14±0.03
0.13±0.02
The differences in the levels of end-points of chromosomal instability investigated
before and after expeditions were statistically insignificant. There are no pronounced tendencies in the changes of the levels of PCD and TPCD for each expedition. The differences in these parameters between the expeditions may reflect some specific features of
the groups of winterers as well as environmental conditions for each expedition.
Thus, the increase of the levels of metaphases with chromosome aberrations and
chromosome aberration after expeditions indicates the presence of damaging factors in Antarctica. The stable tendencies to a chromosomal aberration rise for each
expedition suggest uniformity of these factors. We recommend registration of endpoints of chromosomal segregation failure as parameters reflected features of groups
of winterers and environmental conditions for each expedition.
REFERENCES
ALBERTINI R. J. , D. ANDERSON, G.R. DOUGLAS et al. 2000. IPCS guidelines for the
monitoring of genotoxic effects of carcinogens in humans. – Mutation Research, 463:111-172.
DECAMPS G., ROSNET E., BACHELARD C. 2004. Psychological reactions to stress during a
winter-over in Antarctica: definition of the winter-over adaptive troubles. – Abstract Volume.
XXVIII SCAR Open Science Conference “Antarctica and the Southern Ocean in the Global
System”, 26-28 July, Bremen, Germany. - Bremen: AWS:196-197.
HSU T.C., WU X., TRIZNA Z.1996. Mutagen sensitivity in human. A comparison between two
nomenclature systems for recording chromatid breaks. – Cancer Genet Cytogenet, 87:127-132
PARRY J.M., AL-OBAIDLY A., AL-WALHAIB M., et al. 2002. Spontaneous and induced
aneuploidy, considerations which may influence chromosome malsegregation. - Mutation
Research, 504:119-129.
BAR4 Page 6
6
A. KENAROVA, V. BOGOEV
TAWN E.J., HOLDSWORTH D. 1991. Mutagen induced chromosome damage in human
lymphocytes. In: D. E. Rooney and B.H. Czepulkowski (Eds.) . – Human Cytogenetics.
Volume II. Malignancy and acquired abnormalities. A practical approach. Irl press, Oxford,
New York, Tokyo:189-208.