Induction of chromosome aberrations inAllium cepaL. root tips on exposure to ballast water

Abstract

Lack of enforced regulations on the exchange of ballast water from oceangoing ships has led to its indiscriminate discharge in the environment. In this study, the cytotoxic and genotoxic effects of ballast water were investigated using the Allium cepa L. test. Bulbs with roots of Allium cepa L. were treated with different concentrations (0.5%, 1%, 5%, and 10%) of ballast water, and after 48 h the root tips were processed for cytological studies by the aceto-orcein squash procedure. All concentrations induced a number of chromosomal aberrations in the root tip cells. The mitotic index decreased significantly (p < 0.05) with increasing concentration. The cytotoxic effects showed strong concentrationdependent root growth inhibition with an EC 50 value of 15% after 72 h.Keywords: Allium cepa L; ballast water; chromosome aberrations; cytotoxicity; genotoxicity IntroductionOceanic transport accounts for more than 80% of total global shipments of commercial cargo. In addition to "intended" cargo, over 12 billion tonnes of ballast water are moved across vast coastal and oceanic domains annually, and are indiscriminately discharged into the environment, due to lack of enforced regulations.Ballast water is often sea water taken on board for stability in one country, and discharged before loading. It is a heavy material placed in the hold of a ship to gain stability. It is one of the primary vectors responsible for the global transport of vegetative and resting stages of aquatic microorganisms as well as for potentially pathogenic bacteria (Carlton and Geller 1993;Ruiz et al. 2000). Control of discharge of ballast water is thus an international issue, handled by the International Maritime Organization (IMO). Internationally, there has been slow but steady progress towards international legally binding controls on ballast water.In Nigeria, ballast water is indiscriminately discharged into the environment, due to lack of enforced IMO regulations. Discharge of ballast water from oil tankers could constitute a significant portion of the oil and other impurities introduced into the environment each year, with consequences for both animal and plant life. Results obtained for the physicochemical parameters for ballast water collected from a multipurpose vessel M/V Thelka in an earlier study by Duru and Okieimen (2011) revealed that the ballast water was basic with an appreciably high concentration of chemical oxygen demand (COD) and high electrical conductivity, heavy metals and total dissolved solids (Table 1).Currently, there is no available literature on the genotoxicity of ballast water discharged from merchant ships in Nigeria in plant systems. The Allium test has been accepted as an excellent first-tier indicator for safety evaluation of cyto-genotoxicity monitoring of chemicals, drinking water, wastewaters and complex mixtures (Fiskesjö 1985). Recent studies using the Allium cepa test include genotoxicity testing of phenoxy herbicide (Yildiz and Evrim (Olorunfemi et al. 2011a(Olorunfemi et al. , 2011b. The objective of th...

Cytogenetic effects of chitosan-capped silver nanoparticles in theAllium cepatest

“…Allium cepa L. has been used to evaluate DNA damage, such as chromosome aberrations, micronuclei and disturbances in the mitotic cycle (Bakare et al 2012;Frescura et al 2012;Olorunfemi et al 2012;Achary et al 2013). Due to its sensitivity, the A. cepa test was the first of nine plants assay systems evaluated by the Gene-Tox Program of the US Environmental Protection Agency (Grant 1994).…”

Genotoxicity assessment of three industrial effluents using the Allium cepa bioassay

“…The results are also a clear indication of the reliability and high sensitivity of the A. cepa assay in the detection of genotoxicity of industrial waste waters because the test system provides information to evaluate action mechanisms of an agent about its effects on the genetic material (clastogenic and/or aneugenic effects). There is also a demonstration that in the A. cepa test, there is usually a relationship between growth retardation, mitotic indices and chromosomal damage (genotoxicity) (Olorunfemi et al, 2012). According to Samuel et al (2010), the onion root growth inhibition test should be integrated in the whole effluent test (WET) program and a specified EC 50 should be fixed as a condition to be met before the disposal of effluent into the environment.…”

Phyto-toxic Influence of an Atrazine-based Selective Herbicide – Arda-force® on Onions (Allium cepa L)

“…The purple (stuttgarter) variety of onion (Allium cepa L) was the test specie used in this study with an average weight and length of 72.90 ± 0.38 g and 6.49 ± 0.05 respectively. The onions were air-dried for two weeks and in order to expose the meristematic tissues, dead roots at the base were carefully shaved off with the aid of a blade [18,19]. The bulbs were placed in distilled water to prevent the primordial cells from drying up.…”