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Updated: Sep 6, 2025
Separation of Follicular Cells and Oocytes in Ovarian Follicles of Zebrafish
Published on: April 18, 2021
Cylindrospermopsin induces oocyte maturation and disrupts gene expression in zebrafish ovarian follicles
Adriana Carvalho Natal de Moraes1, Hamideh Pourmohammadi Fallah2, Valéria Freitas de Magalhães3
1Institute of Biophysics Carlos Chagas Filho, Federal University of Rio de Janeiro, Rio de Janeiro, RJ 21.941-902, Brazil; Department of Biological Science, University of Calgary, Calgary, AB T2N 1N4, Canada.
Abstract:
There is evidence that cylindrospermopsin (CYN) exerts reproductive toxicity in mice. However, little information is available concerning the toxicity of CYN in nonmammalian vertebrates. Here, we investigated the direct action of CYN on female reproduction by studying germinal vesicle breakdown, transcript abundance, caspase-3 activity, and testosterone production using cultured follicle-enclosed zebrafish oocytes as a model system. Treatment of follicles with 1,000 μg/L CYN significantly increased GVBD, Caspase-3 activity, and hCG-induced testosterone secretion. Exposure to CYN also reduced the abundance of 3βhsd as well as hCG-induced fshr and era transcripts and increased cyp19a1 mRNA levels. In summary, this study provides a framework for a better understanding of the adverse action of CYN on female reproduction in zebrafish and other vertebrate species. The findings are also relevant to developing valid biomarkers for CYN by measuring zebrafish oocyte maturation and gene expression.
Insights
Cylindrospermopsin (CYN) impacts female zebrafish reproduction, increasing germinal vesicle breakdown and altering key gene expression. This research provides insights into CYN
Area of Science:
- Environmental toxicology
- Reproductive biology
- Zebrafish models
Background:
- Cylindrospermopsin (CYN) is a cyanobacterial toxin known to cause reproductive toxicity in mammals.
- Limited data exists on CYN's effects on nonmammalian vertebrate reproduction.
Purpose of the Study:
- To investigate the direct effects of CYN on female reproductive processes in zebrafish.
- To establish zebrafish oocytes as a model for assessing CYN's reproductive toxicity and developing biomarkers.
Main Methods:
- Cultured follicle-enclosed zebrafish oocytes were used as an in vitro model.
- Assessed germinal vesicle breakdown (GVBD), caspase-3 activity, and testosterone production.
- Quantified transcript abundance of key reproductive genes (3βhsd, fshr, era, cyp19a1) following CYN exposure.
Main Results:
- 1,000 μg/L CYN significantly increased GVBD, caspase-3 activity, and hCG-induced testosterone secretion.
- CYN exposure reduced 3βhsd, hCG-induced fshr, and era transcript levels.
- CYN exposure increased cyp19a1 mRNA levels.
Conclusions:
- CYN directly interferes with female zebrafish reproductive processes, including oocyte maturation and steroidogenesis.
- Gene expression alterations in response to CYN suggest disruption of key reproductive pathways.
- Zebrafish oocyte maturation and gene expression can serve as potential biomarkers for CYN toxicity.
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