Mutation Research, 244 (1990) 295-298 295 Elsevier

MUTLET 0377

Clastogenic effects of cesium chloride on mouse bone marrow cells in vivo

Aditi Ghosh, Archana Sharma and Geeta Talukder

Centre of Advanced Study in Cell and Chromosome Research, Department of Botany, University of Calcutta, Calcutta - 700 019 (India)

(Accepted 15 March 1990)

Keywords." Caesium chloride; Chromosome aberrations; Mouse bone marrow cells

Summary

Clastogenic effects of cesium chloride (CsC1) on mouse bone marrow cells in vivo following oral ad- ministration were studied after 24 h. The incidence of chromosome aberrations increased linearly with in- creasing concentrations of the chemical from 1/20th to 1/5th of the LDso. The frequency of cell division was also enhanced by the lower doses but higher doses were mitostatic. This report is the first on the clastogenici- ty of cesium on animals.

Cesium is an alkali metal of the group IA able to partially substitute for potassium or sodium. In the chloride form, it is the most toxic of all members of this group. Though present in trace amounts in vegetables and animal tissues, yet, higher doses of cesium have been found to be toxic. It has acquired increasing importance due to its presence in plants grown in soil contaminated with radionucleotides f rom atomic fallout (Bunzl et al., 1987).

Very little information is available on the clastogenic effects of cesium salts. The present in- vestigation was therefore undertaken to study the effect of cesium chloride on mammalian cell divi- sion in vivo.

Correspondence: Dr. A. Ghosh, Centre of Advanced Study in Cell and Chromosome Research, Department of Botany, University of Calcutta, 35, Ballygunge Circular Road, Calcutta - 700 019 (India).

Materials and methods

Laboratory-bred female Swiss albino mice (8-10 weeks of age and weighing 28-30 g) were used as the test system.

Mice were administered orally different doses (125, 250 and 500 mg/kg body weight) of cesium chloride (CsC1, molecular weight 168.36, from Sisco Research Laboratories, Bombay). These con- centrations were calculated as fractions of the LDso dose (see Preston et al., 1987) determined for this particular chemical. The LDso dose was found to be 2500 mg/kg body weight for female mice. The mice were maintained on standard commercial diet (Gold Mohur mouse feed; manufactured by Lipton India Limited) and water was provided ad libitum in temperature-controlled chambers. Three sets of experiments were carried out using 5 mice per set. A group of animals administered with distilled water was used as control (C) (Table 1).

0165-7992/90/$ 03.50 © 1990 Elsevier Science Publishers B.V. (Biomedical Division)

296

TABLE 1

SCHEMATIC PRESENTATION OF THE EXPERIMENTAL

PROTOCOL

Group a Chemical Dose Fraction of

used (mg/kg) LDs0

C Distilled

water

1 Cesium chloride 125 1/20

II 250 1/10

II! 500 1/5

aEach group includes 5 mice per set.

Mice were killed by cervical dislocation 24 h after a single oral administration of cesium chloride. Two hours before sacrifice, all animals were in- jected intraperitoneally with colchicine at 4 mg/kg. Bone marrow was flushed out into tubes and prepared for analysis of chromosomal aberrations following the usual hypotonic acetic-acid-ethanol fixation and Giemsa staining schedule (see Sharma and Sharma, 1980).

Slides were coded and scored blind for the presence of dividing cells and chromosomal abnor- malities. 50 well-scattered metaphase plates per animal and a total of 250 metaphase plates per treatment group were observed for chromosomal aberrations. Types of chromosomal aberrations in- clude both chromatid and chromosomal breaks which calculated as: single chromatid, 1 break; 2 chromatids, 2 breaks; dicentrics which were calculated as 2 or 3 or more breaks and a few gaps. 5000 cells per treatment group (1000 cells/animal) were scored to estimate the mitotic index. Observa- tions were from the 3 sets using the 3 concentra- tions of the chemical and the control mice separate- ly. The data were statistically analysed for dose response with Student's t test established at P ~<0.001 and P ~<0.05.

Results and discussion

Observations were made 24 h after the ad- ministration of cesium chloride in concentrations of 125, 250 and 500 mg/kg body weight. The

TABLE 2

MITOTIC INDEX 1N BONE MARROW OF MICE

TREATED WITH CESIUM CHLORIDE

Group Chemical Dose Mitotic

used (mg/kg) cells a

(mean %)

C Distilled - 3.85 _+ 0.59

water

I Cesium chloride 125 4.1 _+0.57

II 250 3.95 _+ 0.64

III 500 2.9 _+ 057*

a Figures are expressed as mean + standard deviation.

*P~<0.001.

mitotic index was increased by the 2 lower doses (125 mg/kg and 250 mg/kg body weight) compared to the control. With the highest dose, however, the mitotic index was reduced (Table 2). Cesium chloride therefore has a mitogenic action at the lower doses but not at a statistically significant level. The present results support earlier observa- tions that metals may stimulate division in lym- phocytes at lower concentrations (see Sharma and Talukder, 1987).

A single exposure to cesium chloride in mice significantly enhanced the frequency of aberrant

TABLE 3

TOTAL CHROMOSOMAL ABERRATIONS IN BONE

M A R R O W CELLS OF MICE TREATED WITH CESIUM

C H L O R I D E

Group a Chemical Dose Total

used (mg/kg) aberrant

metaphases b

(mean 07o)

C Distilled - 4.62 + 2.27

water

I Cesium chloride 125 13.28 _+ 2.18"

11 250 16.28+3.23"

III 500 22.99+3.2 *

a Numbers of cells scored per set, 250.

b Figures are expressed as mean _+ standard deviation.

*P~<O.05.

TABLE 4

P E R C E N T A G E OF C H R O M O S O M A L BREAKS AND NUMBER OF BREAKS PER CELL

IN BONE M A R R O W CELLS OF MICE TREATED WITH CESIUM CHLORIDE

Group Chemical used Dose (mg/kg) Percentage of Breaks per

breaks a cell a

C Distilled water - 1.6 +_ 0.48 0.032 _+ 0.009

1 Cesium chloride 125 8.8 +_ 2.68 0.08 + 0.25

11 250 13.3 + 3.63 0.124 + 0.014

III 500 23.6 _+ 3.57 0.132 _+ 0.032

a Figures are expressed as mean +_ standard deviation.

297

metaphases as compared with the control. A dose- dependent increase in aberrant cells was clearly observed for the oral route of administration (Table 3). The highest dose was the most toxic and was considered to be the maximum tolerated dose. The mean value for the 5 untreated control mice was 4.62°7o aberrant cells. This trend has been recorded with another metal of the same group, potassium bromate (see Fujie et al., 1988).

The clastogenic property of cesium chloride is shown by the high frequency of chromosome breaks induced. The percentage of breaks indicates a very significant increase, related to a certain ex- tent to the dosage used. The same trend was also reflected in the number of breaks per cell (Table 4). Aberrations which were observed include breaks, dicentrics and a few gaps. No other types of aberra- tion were observed. The metal has no effect on the spindle.

Earlier workers had reported toxic effects of cesium salts on living organisms (see Cochran et al., 1950; Relman, 1956; Johnson et al., 1956) but no information was available on the clastogenicity of the metal on animals.

During the present investigation, a significant dose-dependent increase in the number of chromosomal aberrations was observed with all the concentrations of the chemical administered. The mitotic index was enhanced by the lower doses (125 and 250 mg/kg body weight) of the chemical although not at a statistically significant level, but higher doses were toxic.

Cesium chloride was therefore found to be

clastogenic following oral administration in mice in vivo. The report is the first on this metal.

Acknowledgements

The authors are grateful to the University Grants Commission and Council of Scientific and In- dustrial Research, New Delhi for financial assistance and to Professor A.K. Sharma, Pro- gramme Co-ordinator, Centre of Advanced Study in Cell and Chromosome Research, Department of Botany, University of Calcutta for facilities and encouragement.

References

Bunzl, K., and W. Kracke (1987) Soil to plant transfer of

plutonium-239 plus 240, plutonium-238, americium-241,

cesium-137 and strontium-90, from global fallout in fluor and bran from wheat, rye, barley and oats, as obtained by

field measurements , Sci. Total. Environ. , 63, 111-124. Cochran , K.W., J. Doull, M. Mazur and K.P. Dubois (1950)

Acute toxicity of zarconium, columbium, strontium, lan-

thanum, cesium, tanta lum and yttrium, Arch. Ind. Hyg., 1, 637-650.

Fujie, K., H. Shimazu, M. Matsuda and T. Sugiyama (1988)

Acute cytogenetic effects of potassium bromate on rat bone

cells in vivo, Mutat ion Res., 206, 455-458. Johnson , G.T. , T.R. Lewis and W.D. Wagner (1975) Acute tox-

icity of cesium and rubidium compounds , Toxicol. Appl .

Pharmacol . , 32, 239. Preston, R.J . , B.J. Dean, S. Galloway, H. Holden, A.F. McFee

and M. Shelby (1987) Mammal ian in vivo cytogenetic assays: analysis of chromosome aberrations in bone marrow cells,

Muta t ion Res., 189, 157-165.

298

Relman, A.S. (1956) The physiological behaviour of rubidium and cesium, Yale J. Biol. Med., 29, 248.

Sharma, A., and G. Talukder (1987) Effects of metals on chromosomes of higher organisms, Environ. Mutagen., 9, 191-226.

Sharma, A.K., and A. Sharma (1980) Chromosome Tech- niques, Theory and Practice, 3rd edn., Butterworths, London, pp. 354-355.

Communicated by J.M. Gentile