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Abstract Background The teleost fish Fundulus heteroclitus inhabit estuaries heavily polluted with persistent and bioaccumulative chemicals. While embryos of parents from polluted sites are remarkably resistant to toxic sediment and develop normally, embryos of parents from relatively clean estuaries, when treated with polluted sediment extracts, are developmentally delayed, displaying deformities characteristic of pollution-induced embryotoxicity. To gain insight into parental effects on sensitive and resistant phenotypes during late organogenesis, we established sensitive, resistant, and crossed embryo families using five female and five male parents from relatively clean and predominantly PAH-polluted estuaries each, measured heart rates, and quantified individual embryo expression of 179 metabolic genes. Results Pollution-induced embryotoxicity manifested as morphological deformities, significant developmental delays, and altered cardiac physiology was evident among sensitive embryos resulting from crosses between females and males from relatively clean estuaries. Significantly different heart rates among several geographically unrelated populations of sensitive, resistant, and crossed embryo families during late organogenesis and pre-hatching suggest site-specific adaptive cardiac physiology phenotypes relative to pollution exposure. Metabolic gene expression patterns (32 genes, 17.9%, at p < 0.05; 11 genes, 6.1%, at p < 0.01) among the embryo families indicate maternal pollutant deposition in the eggs and parental effects on gene expression and metabolic alterations. Conclusion Heart rate differences among sensitive, resistant, and crossed embryos is a reliable phenotype for further explorations of adaptive mechanisms. While metabolic gene expression patterns among embryo families are suggestive of parental effects on several differentially expressed genes, a definitive adaptive signature and metabolic cost of resistant phenotypes is unclear and shows unexpected sensitive-resistant crossed embryo expression profiles. Our study highlights physiological and metabolic gene expression differences during a critical embryonic stage among pollution sensitive, resistant, and crossed embryo families, which may contribute to underlying resistance mechanisms observed in natural F. heteroclitus populations living in heavily contaminated estuaries.
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Measuring complex phenotypes: A flexible high-throughput design for micro-respirometry.
Variation in tissue-specific metabolism between species and among individuals is thought to be adaptively important; however, understanding this evolutionary relationship requires reliably measuring this trait in many individuals. In most higher organisms, tissue specificity is important because different organs (heart, brain, liver, muscle) have unique ecologically adaptive roles. Current technology and methodology for measuring tissue-specific metabolism is costly and limited by throughput capacity and efficiency. Presented here is the design for a flexible and cost-effective high-throughput micro-respirometer (HTMR) optimized to measure small biological samples. To verify precision and accuracy, substrate specific metabolism was measured in heart ventricles isolated from a small teleost, Fundulus heteroclitus, and in yeast (Saccharomyces cerevisiae). Within the system, results were reproducible between chambers and over time with both teleost hearts and yeast. Additionally, metabolic rates and allometric scaling relationships in Fundulus agree with previously published data measured with lower-throughput equipment. This design reduces cost, but still provides an accurate measure of metabolism in small biological samples. This will allow for high-throughput measurement of tissue metabolism that can enhance understanding of the adaptive importance of complex metabolic traits.
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- PAR ID:
- 10220602
- Date Published:
- Journal Name:
- bioRxiv
- Volume:
- 2020
- Page Range / eLocation ID:
- 2020.03.16.993550
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1101/2020.03.16.993550
