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A C. elegans screening platform for the rapid assessment of chemical disruption of germline function.

Allard P, Kleinstreuer NC, Knudsen TB, Colaiácovo MP - Environ. Health Perspect. (2013)

Bottom Line: Despite the developmental impact of chromosome segregation errors, we lack the tools to assess environmental effects on the integrity of the germline in animals.We confirmed the effect of select compounds on germline integrity by monitoring germline apoptosis and meiotic progression.This C. elegans assay provides a comprehensive strategy for assessing environmental effects on germline function.

View Article: PubMed Central - PubMed

Affiliation: Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115 , USA.

ABSTRACT

Background: Despite the developmental impact of chromosome segregation errors, we lack the tools to assess environmental effects on the integrity of the germline in animals.

Objectives: We developed an assay in Caenorhabditis elegans that fluorescently marks aneuploid embryos after chemical exposure.

Methods: We qualified the predictive value of the assay against chemotherapeutic agents as well as environmental compounds from the ToxCast Phase I library by comparing results from the C. elegans assay with the comprehensive mammalian in vivo end point data from the ToxRef database.

Results: The assay was highly predictive of mammalian reproductive toxicities, with a 69% maximum balanced accuracy. We confirmed the effect of select compounds on germline integrity by monitoring germline apoptosis and meiotic progression.

Conclusions: This C. elegans assay provides a comprehensive strategy for assessing environmental effects on germline function.

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Related in: MedlinePlus

Screening of environmental chemicals. Worms were exposed for either 24 hr (A) or 65 hr (B) to each compound, at a concentration of 100 µM [except for mancozeb, dicofol, 2-(thiocyanomethylthio) benzothiazole (TCMTB), phosalone, chlorophene, endosulfan, parathion-methyl, which were further diluted 10-fold, and chlorpyrifos-methyl, which was used at 1 µM, to circumvent lethality]. The number of green embryos per worm was recorded and corrected for the average number of embryos found in each worm. The number was then expressed as the log fold ratio over DMSO. Chemicals are listed in order in Supplemental Material, Tables S2 and S3 (http://dx.doi.org/10.1289/ehp.1206301). The compounds were categorized according to their assessed mammalian reproductive toxicity [i.e., the number of mammalian end points for which they were positive: high reproductive toxicity (> 2 end points), intermediate reproductive toxicity (1 end point), and no reproductive toxicity (0 end points)]. At 65 hr, the mean value of fold-induction for the high and intermediate reproductive toxicity groups was significantly higher than the no–reproductive toxicity group (p = 0.008). Each chemical was tested three times.
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f3: Screening of environmental chemicals. Worms were exposed for either 24 hr (A) or 65 hr (B) to each compound, at a concentration of 100 µM [except for mancozeb, dicofol, 2-(thiocyanomethylthio) benzothiazole (TCMTB), phosalone, chlorophene, endosulfan, parathion-methyl, which were further diluted 10-fold, and chlorpyrifos-methyl, which was used at 1 µM, to circumvent lethality]. The number of green embryos per worm was recorded and corrected for the average number of embryos found in each worm. The number was then expressed as the log fold ratio over DMSO. Chemicals are listed in order in Supplemental Material, Tables S2 and S3 (http://dx.doi.org/10.1289/ehp.1206301). The compounds were categorized according to their assessed mammalian reproductive toxicity [i.e., the number of mammalian end points for which they were positive: high reproductive toxicity (> 2 end points), intermediate reproductive toxicity (1 end point), and no reproductive toxicity (0 end points)]. At 65 hr, the mean value of fold-induction for the high and intermediate reproductive toxicity groups was significantly higher than the no–reproductive toxicity group (p = 0.008). Each chemical was tested three times.

Mentions: We tested the utility of the meiotic screen by comparing results from a panel of 47 compounds with selected mammalian reproductive end points in ToxRefDB that were indicative of decreased female fertility. These in vivo end points included decreased implantation sites, litter size, early postnatal pup survival, overall reproductive success, reproductive performance, and fertility as well as ovarian morphology defects. The selected compounds were grouped into three categories according to the number of mammalian end points they were positive for: a) high reproductive toxicity (32 end points), b) intermediate reproductive toxicity (1 end point), and c) no reproductive toxicity (0 end points). The chemicals that were tested, their ranking by fold induction in the C. elegans assay, and their corresponding mammalian in vivo end point data are presented in Supplemental Material, Tables S2 and S3 (http://dx.doi.org/10.1289/ehp.1206301). As shown in Figure 3, at 65 hr, there is a statistically significant partitioning of all reproductive toxicants (high and intermediate) from compounds that are not reproductive toxicants (p = 0.008; two-tailed Mann–Whitney U test, 95% CI). The 24-hr exposure showed a trend toward significance (p = 0.08). These results indicate a clear enrichment of reproductive toxicants as positive hits from the screen, suggesting that chemical aneugenicity is a likely source of reproductive toxicity in mammals.


A C. elegans screening platform for the rapid assessment of chemical disruption of germline function.

Allard P, Kleinstreuer NC, Knudsen TB, Colaiácovo MP - Environ. Health Perspect. (2013)

Screening of environmental chemicals. Worms were exposed for either 24 hr (A) or 65 hr (B) to each compound, at a concentration of 100 µM [except for mancozeb, dicofol, 2-(thiocyanomethylthio) benzothiazole (TCMTB), phosalone, chlorophene, endosulfan, parathion-methyl, which were further diluted 10-fold, and chlorpyrifos-methyl, which was used at 1 µM, to circumvent lethality]. The number of green embryos per worm was recorded and corrected for the average number of embryos found in each worm. The number was then expressed as the log fold ratio over DMSO. Chemicals are listed in order in Supplemental Material, Tables S2 and S3 (http://dx.doi.org/10.1289/ehp.1206301). The compounds were categorized according to their assessed mammalian reproductive toxicity [i.e., the number of mammalian end points for which they were positive: high reproductive toxicity (> 2 end points), intermediate reproductive toxicity (1 end point), and no reproductive toxicity (0 end points)]. At 65 hr, the mean value of fold-induction for the high and intermediate reproductive toxicity groups was significantly higher than the no–reproductive toxicity group (p = 0.008). Each chemical was tested three times.
© Copyright Policy - public-domain
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3672921&req=5

f3: Screening of environmental chemicals. Worms were exposed for either 24 hr (A) or 65 hr (B) to each compound, at a concentration of 100 µM [except for mancozeb, dicofol, 2-(thiocyanomethylthio) benzothiazole (TCMTB), phosalone, chlorophene, endosulfan, parathion-methyl, which were further diluted 10-fold, and chlorpyrifos-methyl, which was used at 1 µM, to circumvent lethality]. The number of green embryos per worm was recorded and corrected for the average number of embryos found in each worm. The number was then expressed as the log fold ratio over DMSO. Chemicals are listed in order in Supplemental Material, Tables S2 and S3 (http://dx.doi.org/10.1289/ehp.1206301). The compounds were categorized according to their assessed mammalian reproductive toxicity [i.e., the number of mammalian end points for which they were positive: high reproductive toxicity (> 2 end points), intermediate reproductive toxicity (1 end point), and no reproductive toxicity (0 end points)]. At 65 hr, the mean value of fold-induction for the high and intermediate reproductive toxicity groups was significantly higher than the no–reproductive toxicity group (p = 0.008). Each chemical was tested three times.
Mentions: We tested the utility of the meiotic screen by comparing results from a panel of 47 compounds with selected mammalian reproductive end points in ToxRefDB that were indicative of decreased female fertility. These in vivo end points included decreased implantation sites, litter size, early postnatal pup survival, overall reproductive success, reproductive performance, and fertility as well as ovarian morphology defects. The selected compounds were grouped into three categories according to the number of mammalian end points they were positive for: a) high reproductive toxicity (32 end points), b) intermediate reproductive toxicity (1 end point), and c) no reproductive toxicity (0 end points). The chemicals that were tested, their ranking by fold induction in the C. elegans assay, and their corresponding mammalian in vivo end point data are presented in Supplemental Material, Tables S2 and S3 (http://dx.doi.org/10.1289/ehp.1206301). As shown in Figure 3, at 65 hr, there is a statistically significant partitioning of all reproductive toxicants (high and intermediate) from compounds that are not reproductive toxicants (p = 0.008; two-tailed Mann–Whitney U test, 95% CI). The 24-hr exposure showed a trend toward significance (p = 0.08). These results indicate a clear enrichment of reproductive toxicants as positive hits from the screen, suggesting that chemical aneugenicity is a likely source of reproductive toxicity in mammals.

Bottom Line: Despite the developmental impact of chromosome segregation errors, we lack the tools to assess environmental effects on the integrity of the germline in animals.We confirmed the effect of select compounds on germline integrity by monitoring germline apoptosis and meiotic progression.This C. elegans assay provides a comprehensive strategy for assessing environmental effects on germline function.

View Article: PubMed Central - PubMed

Affiliation: Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115 , USA.

ABSTRACT

Background: Despite the developmental impact of chromosome segregation errors, we lack the tools to assess environmental effects on the integrity of the germline in animals.

Objectives: We developed an assay in Caenorhabditis elegans that fluorescently marks aneuploid embryos after chemical exposure.

Methods: We qualified the predictive value of the assay against chemotherapeutic agents as well as environmental compounds from the ToxCast Phase I library by comparing results from the C. elegans assay with the comprehensive mammalian in vivo end point data from the ToxRef database.

Results: The assay was highly predictive of mammalian reproductive toxicities, with a 69% maximum balanced accuracy. We confirmed the effect of select compounds on germline integrity by monitoring germline apoptosis and meiotic progression.

Conclusions: This C. elegans assay provides a comprehensive strategy for assessing environmental effects on germline function.

Show MeSH
Related in: MedlinePlus