Induction of Mitotic Abnormalities in Onion Root-Tips by Tobacco Smoke Condensate

Abstract

The association of chromosomal abnormalities with malignant disease in vivo has been demonstrated by many investigators (see Porter et al. 1969). In vitro studies with lung tissues obtained from human fetus and young kittens (Na kanishi et al. 1959, Awa et al. 1961, mouse lung fragments (Bouchard and May 1960) and the KB line of mammalian cells in culture (Thayer and Kensler 1964) have indicated that cigarette smoke fractions have definite cytologic influences.Quantitative evaluation of such effects should provide information which may be important to health related research on tobacco.It seems obvious that experimentation with plants is faster and easier than the standard mouse skin bioassay which is commonly employed in assessing the biolo gical effects of tobacco smoke fractions and their components. The present investi gation was, therefore, conducted to ascertain the influence of water-soluble extract of tobacco smoke condensate (TSC) on the mitotic process in young roots obtained from onion bulbs. An attempt was made to investigate the feasibility of utilizing plant tissues for a rapid bioassay to detect the cytological effects caused by TSC. Material and methodsCommercially available bulbs of onion (Allium cepa) were utilized in the pre sent study. To obtain the roots, several bulbs were placed with their basal side facing downwards over small jars containing 60ml of glass-distilled water. The water in the jars was replaced at 24-hour intervals. After about 72hours, when the roots had emerged from the bulbs and were about one inch in length, the water was replaced by known concentrations of water-soluble extract of tobacco smoke con densate (TSC).

Nicotine-induced loss of cortical microtubules in root tip cells of alfalfa (Medicago sativa).

“…The effect of tobacco smoke condensates in inducing abnormal mitosis has been documented in a number of investigations, including those with onion root tip cells. In onion root tip cells, water-soluble extract of tobacco smoke condensate caused irregular mitotic divisions, which included failure of chromosomes to align on the metaphase plate and lagging of chromosomes at anaphase (Bhalla et al 1973). Since nicotine is regarded as one of the major constituents of tobacco smoke, it is possible that the irregular mitotic divisions observed in onion root tip cells (Bhalla et al 1973) resulted from the adverse effect of the nicotine fraction of tobacco condensate on spindle microtubules.…”

Threshold dose of cytogenetic toxicity of lindane, malathion and metacid in allium cepa root-tip cells.

“…Desired randomness in counting of the dividing cells was achieved by the method suggested by Bhalla et al (1973). The control variant of bulbs were all along grown over normal tap water with one change after 24 hrs.…”

Cytogenetic toxicity ofAloe vera(a medicinal plant)

“…Abnormalities in cells were categorized as chromosomal aberrations (i.e., structural and numerical) and division disruptions. The mitotic index (MI) was also calculated by dividing the number of cells in mitosis to total number of cells observed (Bhalla et al, 1973).…”