Sister Chromatid Exchange Analysis In Chromosomes Of Goats Inhabiting Industrial Area
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Date
2008
Journal Title
Journal ISSN
Volume Title
Publisher
TANUVAS, Chennai
Abstract
With continuous increase in the number of industries, there is a potential threat
of industrial pollution to livestock. Many toxic industrial residues and pollutants find
their way into animal tissues because of extensive animal husbandry rearing systems
and cause several health and reproductive problems. Of late, the sister chromatid
exchange (SCE) is the most sensitive and reliable test system and has been used as
indices of genotoxicity caused by exogenous agents.
To assess the mean SCEs frequency and chromosome aberrations, blood
samples collected from 10 male and 10 female goats (20 animals) inhabiting within a
radial distance of 5 km from the industrial area viz. Noyial river belt, Karur district,
Tamil Nadu (exposed) and, from 10 male and 10 female goats (20 animals) living outside a radial distance of 15 km (control) were utilized. The cultures were set up
with RPMI 1640 culture medium and Pokeweed Mitogen (PWM). In addition, the
cultures were supplemented with bromodeoxyuridine (BrdU) for two cell cycles. The
cultures were incubated at 37.5ยบ C for 64 h. Air-dried slides prepared were stained as
per Fluorescent plus Giemsa (FPG) technique. To assess the numerical and structural
chromosome aberrations, duplicate cultures were set up from each of the blood
samples collected without incorporation of BrdU and harvested as per standard
protocol and the air-dried slides were G-banded and karyotypes prepared.
The normal chromosome complement of 60, XX in females and 60, XY in
males was observed in all the samples collected from control and exposed population
of non-descript goats. No gross structural and numerical chromosome abnormalities
were noticed in all animals screened based on G-banding and karyotyping.
The mitotic drive for control and exposed population was 37.58 and
26.13 per cent respectively. The mitotic drive in exposed population was
significantly (P< 0.01) lower when compared to control animals. The mitotic index
for control and exposed population was 12.49 and 11.49 per cent
respectively. lthough there was a decrease in mitotic index in exposed population it
was not statistically significant.
The frequency of SCEs did not follow Poisson distribution in both control and
exposed population of non-descript goats. The pooled mean S.E (range) of SCEs
frequency for control and exposed population of non-descript goats were
4.83 and 12.98 respectively. There was significant
(P<0.01) increase in SCEs frequency of non-descript goats (exposed) reared in
industrial area and confirms that the effluents from textile industries are possible
cause for genotoxic pollution. Constant surveillance on the effect of industrial
pollution on chromosomes of livestock by SCE assay would pave way to contain the
degradation of environment.
The mean S.E (range) of SCEs frequency for males and females in control
population was 4.22 0.10 (1-11) and 5.45 0.13 (1-11) and in exposed population
was 13.60 0.08 (8-18) and 12.37 0.13 (8-19) respectively. In general, the range of
SCE frequency increased with increase in mean SCEs frequency. No significant
difference was observed between the sexes in control and exposed population.
The number of SCEs in chromosome 1 was significantly (P< 0.05) higher than
that expected from relative chromosomal length. The chromosomes 2, 14 and X
showed no SCEs in all the metaphases observed, though the chromosome 2 and X
were relatively long compared to other chromosomes.
The decrease in mitotic drive and mitotic index of the exposed population of
non-descript goats reveals decreased cell proliferation rate in goats exposed to
pollution. The increased mean SCEs frequency in exposed animals confirms that the
effect of pollution is genotoxic and warrants constant surveillance. Further more, the
study also revealed that sex is not a major source of variation of mean SCEs
frequency and the occurrence of SCEs in not influenced by relative length of
chromosomes.