Chrysotile and amosite asbestos induce germ-line aneuploidy in Drosophila

Our plain-English summary of Chrysotile and amosite asbestos induce germ-line aneuploidy in Drosophila, by C. Osgood, D. Sterling (Mutation Research, 1991).

The study

• Authors: C. Osgood, D. Sterling
• Journal: Mutation Research
• Published: 1991;261(1):9-13
• Cited by: 5 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Asbestos toxicity is a problem of considerable public concern and debate, however little is known regarding the biological targets of asbestos fibers. Prompted by reports that asbestos induces aneuploidy in cultured mammalian cells, we have investigated whether asbestos induces germ-line aneuploidy in Drosophila melanogaster. Using the ZESTE genetic test system, we have shown that both chrysotile and amosite asbestos induce sex-chromosome aneuploidy in Drosophila oocytes. Chrysotile appeared to be the more effective agent because it induced approximately equal frequencies of chromosome gain and chromosome loss, while amosite induced chromosome loss only. Two other asbestiform minerals, crocidolite and tremolite, were ineffective in this assay system. These results suggest that possible germ-line effects of asbestos should be considered in evaluating its potential impact on human health.

In plain English

This was a laboratory experiment in fruit flies (Drosophila melanogaster), not a study of people. The authors fed young female flies a slurry of one of four asbestos materials in sugar water for 3 days. Chrysotile, crocidolite and amosite were given at 25 and 5 mg/ml, and a non-fibrous form of tremolite at 50, 25 and 5 mg/ml. They then counted offspring that had gained or lost a sex chromosome (aneuploidy), a sign of errors in the mother's egg cells. With chrysotile at 25 mg/ml, 0.14% of offspring were aneuploid, about 9 times the control rate of 0.016%, with roughly equal gains and losses. The 5 mg/ml chrysotile dose was also significant (0.07%). Amosite at 25 mg/ml gave 0.049%, about 3 times the control rate, mostly losses; its lower dose was not significant. Crocidolite and tremolite were not significant overall. The authors could not measure how much asbestos the flies ate or whether it reached the eggs. They concluded that chrysotile and amosite induced germ-line aneuploidy in these flies.

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: Animal experiment: a genetic test in fruit flies (the ZESTE test system) for errors in sex-chromosome number in egg cells
• Who was studied: Laboratory female fruit flies (Drosophila melanogaster), aged 3-4 days, fed the test materials for 3 days and then mated. Their offspring were collected in three broods and scored; tens of thousands of offspring were counted per group (for example 37207 in the controls). Laboratory at Old Dominion University, Norfolk, Virginia, U.S.A.
• Exposure: Chrysotile, crocidolite, amosite and non-fibrous tremolite, suspended in 2% sucrose-water and fed at 25 and 5 mg/ml. Tremolite was also tested at 50 mg/ml. Controls were fed 2% sucrose alone.
• Main results:
  • Chrysotile at 25 mg/ml: 0.14% of offspring were aneuploid (chromosome loss plus gain), about 9 times the control rate of 0.016%. The authors described this difference as highly significant.
  • With chrysotile, roughly equal numbers of chromosome-gain and chromosome-loss offspring were recovered.
  • Chrysotile at 5 mg/ml: the response was also statistically significant, with 0.07% aneuploids. Two of the 6 abnormal offspring came from chromosome gain.
  • Amosite at 25 mg/ml: 0.049% aneuploids, about 3 times the control rate of 0.016%. Eight of the 9 abnormal offspring were due to chromosome loss.
  • Amosite at 5 mg/ml: results were not statistically significant.
  • Crocidolite: pooled results were negative at both doses. The one exception was a single brood (Brood B) at 5 mg/ml, where chromosome-loss offspring differed significantly from controls (p = 0.015). No such effect was seen at 25 mg/ml.
  • Non-fibrous tremolite did not produce significant levels of aneuploidy at any dose tested (50, 25 or 5 mg/ml).
  • The asbestos materials were not toxic to the flies at the doses tested.
• The authors' conclusion: The authors concluded that chrysotile and amosite induced germ-line aneuploidy in Drosophila. They suggested that germ-line effects of chrysotile may be important for human health assessment, and that epidemiologic studies of aneuploidy and birth defects in the children of asbestos workers are worth pursuing. They framed this as applying only to the extent that fly results apply to humans.
• Limitations the authors state:
  • The thick asbestos slurries could not be spread evenly on the feeding surfaces.
  • The authors could not measure how much asbestos the flies swallowed, or whether it reached the egg cells.
  • Only a non-fibrous form of tremolite was tested; the authors said tests with fibrous tremolite are desirable.
  • Feeding of fly larvae, which might deliver the material more efficiently, could not be tested because too little material was available.
  • The authors noted that the results apply to humans only to the extent that fruit-fly results can be applied to humans.

Topics

Medical terms in this study, explained in our Lexicon: Chrysotile, Amosite, Asbestiform, Crocidolite, Tremolite.

Related studies

• Refractory ceramic fibers (RCFs) induce germline aneuploidy in Drosophila oocytes — C.J. Osgood (1994)
• Intracellular protein binding to asbestos induces aneuploidy in human lung fibroblasts — R.A. MacCorkle, S.D. Slattery, et al. (2006)
• Multipolar mitosis and aneuploidy after chrysotile treatment: a consequence of abscission failure and cytokinesis regression — B.A. Cortez, P. Rezende-Teixeira, et al. (2016)
• Induction by asbestos fibers of anaphase abnormalities: mechanism for aneuploidy induction and possibly carcinogenesis — T.W. Hesterberg, J.C. Barrett (1985)
• Detection of aneuploidy-inducing carcinogens in the Syrian hamster embryo (SHE) cell transformation assay — D.P. Gibson, M.J. Aardema, et al. (1995)
• Chromosome nondisjunction during bipolar mitoses of binucleated intermediates promote aneuploidy formation along with multipolar mitoses rather than chromosome loss in micronuclei induced by asbestos — T. Zhang, L. Lv, et al. (2017)

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