Adsorption of nucleic acids on asbestos fibers in vitro

Our plain-English summary of Adsorption of nucleic acids on asbestos fibers in vitro, by V. Misra, Q. Rahman, P.N. Viswanathan (Toxicology Letters, 1983).

The study

• Authors: V. Misra, Q. Rahman, P.N. Viswanathan
• Journal: Toxicology Letters
• Published: 1983;15(2-3):187-91
• Cited by: 7 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Adsorption of DNA and RNA, accompanied by liberation of orthophosphate, occurred on contact with chrysotile asbestos fibers. This indicated that interaction of macromolecules and their components may be a factor, possibly involved in the manifestation of the toxic effect of asbestos fibers.

In plain English

This was a laboratory experiment done at the Industrial Toxicology Research Centre in Lucknow, India. No people or animals were studied. The authors mixed chrysotile asbestos dust with purified DNA from calf thymus or RNA from yeast. They kept the mixtures at 37°C for 72 hours, using 5 to 40 mg of dust per tube, with dust-free tubes as controls. As more dust was added, less RNA or DNA stayed in the surrounding liquid. With 40 mg of dust, 60% of the RNA stuck to the dust. For DNA, 5 mg of dust took up about half, and adding more dust did not take up more. The dust also released phosphate from the DNA and RNA, in what the authors called significant amounts. The amount released did not rise in step with the amount of dust, and no increase in free nucleosides was found. The authors concluded that DNA and RNA appear to attach to asbestos fibers. They said it could not yet be decided whether this contributes to the biological effects of asbestos, including cancer.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: In vitro (test-tube) laboratory experiment
• Who was studied: No human or animal subjects. Commercially purchased calf thymus DNA and yeast RNA (British Drug Houses, U.K.), tested in triplicate tubes at the Industrial Toxicology Research Centre, Lucknow, India
• Exposure: Chrysotile asbestos dust (fiber size under 30 micrometres) as a 10 mg/ml suspension. 0.5 to 4.0 ml of suspension (5 to 40 mg of dust) was added to 1.0 ml of a 1 mg/ml DNA or RNA solution and incubated at 37°C for 72 hours. Tubes without dust served as controls.
• Main results:
  • As the amount of chrysotile dust increased, the RNA or DNA remaining in the liquid decreased. With 40 mg of dust, 60% of the RNA was adsorbed onto the dust.
  • 5 mg of dust adsorbed about half of the DNA. More dust did not adsorb more DNA.
  • Treatment with dust caused no marked change in the ultraviolet spectral characteristics of DNA or RNA.
  • Orthophosphate was released from the RNA and DNA in what the authors described as significant amounts. None was detected from dust incubated without nucleic acid.
  • The amount of phosphate released was not related in a quantitative way to the amount of dust added. Higher amounts of dust may even have inhibited release.
  • Free nucleosides were not detected in increased amounts in tubes containing asbestos.
• The authors' conclusion: The authors concluded that DNA and RNA appear to be adsorbed on asbestos fibers. They said how far this contributes to the biological effects of asbestos, especially its carcinogenicity, cannot be decided at present, though it is possible the adsorption is related to the carcinogenic effect.
• Limitations the authors state:
  • Because the KOH used to release adsorbed material from the dust may break down RNA, quantitative comparisons were not possible.
  • It was not established whether intact nucleic acids or a product formed from them were adsorbed.
  • It is uncertain whether this adsorption is specific to asbestos fibers or also occurs with other mineral fibers.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Chrysotile.

Medical terms in this study, explained in our Lexicon: Chrysotile.

Related studies

• Vitronectin adsorption to chrysotile asbestos increases fiber phagocytosis and toxicity for mesothelial cells — J. Wu, W. Liu, et al. (2000)
• Nucleic acid metabolism in the rat following short-term and prolonged ingestion of chrysotile asbestos or cigarette-smoke condensate — R. Jacobs, M. Weinzweig, et al. (1978)
• Ferritin adsorption on amosite fibers: possible implications in the formation and toxicity of asbestos bodies — B. Fubini, F. Barceló, et al. (1997)
• The adsorption of polyaromatic hydrocarbons on natural and chemically modified asbestos fibers — H. Menard, L. Noel, et al. (1986)
• Protective role of ascorbic acid against asbestos induced toxicity in rat lung: in vitro study — S.G. Khan, S. Ali, et al. (1990)
• The adsorption of biological macromolecules by mineral dusts — R. Desai, R.J. Richards (1978)

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