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Genotoxicity of
Chlorpyrifos, Alpha-thrin, Efekto virikop and Springbok to
onion root tip cells
Asita Okorie Asita* and
Rets’elisitsoe Makhalemele
Department
of Biology, National University of Lesotho, P. O. Roma 180
Maseru, Lesotho, Southern Africa.
*Corresponding author. E-mail:
ao.asita@nul.ls. Tel:
+266 22213171. Fax: +266 22 340000.
Accepted
25 July, 2008 |
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The pesticides, chlorpyrifos, Alpha-thrin, Efekto virikop and
springbok were assessed for cytotoxicity and genotoxicity in
the onion root tip assay.
Onion seeds were germinated on moistened filter paper in
petri dish at room temperature until radicles appeared.
Germinated seeds were exposed to three concentrations of
each pesticide for 20 h. About 1 – 2 mm length of root tip
was cut, fixed in acetic alcohol, washed in ice cold water,
hydrolyzed in warm 1 N HCl, stained with aceto-carmine and
squashed on glass slide. For each treatment, about 3000
cells were scored and classified into interphase and normal
or aberrant division stage. Cytotoxicity was determined by
comparing the mitotic index (MI) of treated cells with that
of the negative control. The MI of cells treated with chlorpyrifos,
Alpha-thrin or
springbok was
half or less, that of the control at one or more doses and
adjudged cytotoxic.
Efekto virikop was not cytotoxic. Genotoxicity was measured
by comparing the number of cells/1000 in aberrant division
stages at each dose with the negative control using the
Mann-Whitney test. Chlorpyrifos was genotoxic (P < 0.05),
inducing chromosome
lagging and bridges, pulverized and stick chromosomes,
multipolar anaphase and telophase.
Efekto
virikop and springbok induced lagging chromosomes.
Alpha-thrin was not genotoxic.
Key
words:
Allium cepa, cytotoxicity, genotoxicity, mitotic
index, pesticides, root tip cells. |
