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  • 1
    Publication Date: 2022-05-26
    Description: Author Posting. © University of Chicago, 2019. This article is posted here by permission of University of Chicago for personal use, not for redistribution. The definitive version was published in Biological Bulletin 237(2), (2019): 90-110, doi: 10.1086/705234.
    Description: Calanus finmarchicus and Calanus glacialis are keystone zooplankton species in North Atlantic and Arctic marine ecosystems because they form a link in the trophic transfer of nutritious lipids from phytoplankton to predators on higher trophic levels. These calanoid copepods spend several months of the year in deep waters in a dormant state called diapause, after which they emerge in surface waters to feed and reproduce during the spring phytoplankton bloom. Disruption of diapause timing could have dramatic consequences for marine ecosystems. In the present study, Calanus C5 copepodites were collected in a Norwegian fjord during diapause and were subsequently experimentally exposed to the water-soluble fraction of a naphthenic North Sea crude oil during diapause termination. The copepods were sampled repeatedly while progressing toward adulthood and were analyzed for utilization of lipid stores and for differential expression of genes involved in lipid metabolism. Our results indicate that water-soluble fraction exposure led to a temporary pause in lipid catabolism, suggested by (i) slower utilization of lipid stores in water-soluble fraction-exposed C5 copepodites and (ii) more genes in the β-oxidation pathway being downregulated in water-soluble fraction-exposed C5 copepodites than in the control C5 copepodites. Because lipid content and/or composition may be an important trigger for termination of diapause, our results imply that the timing of diapause termination and subsequent migration to the surface may be delayed if copepods are exposed to oil pollution during diapause or diapause termination. This delay could have detrimental effects on ecosystem dynamics.
    Description: We thank the Department of Biology at the Norwegian University of Science and Technology (NTNU) for additional funding for ES’s stay at Woods Hole Oceanographic Institution (WHOI); Christoffer H. Hilde for help in the field and in the lab; Siv Anina Etter, Øystein Leiknes, Sofia Soloperto, and Clara P. Igisch for help with the fieldwork; Justyna Świeżak, Mari-Ann Østensen, and Signe D. Løvmo for experimental assistance; and Hanny Rivera for help with bioinformatic analyses at WHOI. The RNA-sequencing work was provided by the Genomics Core Facility (GCF). The GCF is funded by the Faculty of Medicine and Health Sciences at NTNU and the Central Norway Regional Health Authority. AMT was funded by the National Science Foundation (award no. OPP-1746087).
    Description: 2020-10-04
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 2
    Publication Date: 2022-05-26
    Description: © The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Skottene, E., Tarrant, A. M., Altin, D., Olsen, R. E., Choquet, M., & Kvile, K. O. Lipid metabolism in Calanus finmarchicus is sensitive to variations in predation risk and food availability. Scientific Reports, 10(1),(2020): 22322, https://doi.org/10.1038/s41598-020-79165-6.
    Description: Late developmental stages of the marine copepods in the genus Calanus can spend extended periods in a dormant stage (diapause) that is preceded by the accumulation of large lipid stores. We assessed how lipid metabolism during development from the C4 stage to adult is altered in response to predation risk and varying food availability, to ultimately understand more of the metabolic processes during development in Calanus copepods. We used RNA sequencing to assess if perceived predation risk in combination with varied food availability affects expression of genes associated with lipid metabolism and diapause preparation in C. finmarchicus. The lipid metabolism response to predation risk differed depending on food availability, time and life stage. Predation risk caused upregulation of lipid catabolism with high food, and downregulation with low food. Under low food conditions, predation risk disrupted lipid accumulation. The copepods showed no clear signs of diapause preparation, supporting earlier observations of the importance of multiple environmental cues in inducing diapause in C. finmarchicus. This study demonstrates that lipid metabolism is a sensitive endpoint for the interacting environmental effects of predation pressure and food availability. As diapause may be controlled by lipid accumulation, our findings may contribute towards understanding processes that can ultimately influence diapause timing.
    Description: ES was funded by the Department of Biology, Norwegian University of Science and Technology. Support for AMT was provided by the National Science Foundation (NSF) OPP-1746087. KØK was funded by VISTA—a basic research program in collaboration between The Norwegian Academy of Science and Letters, and Equinor. The RNA seq work was provided by the Genomics Core Facility (GCF). GCF is funded by the Faculty of Medicine and Health Sciences at NTNU and Central Norway Regional Health Authority. The authors thank Lotte Thommesen for help conducting the experiment, Mari-Ann Østensen for performing RNA extraction with ES and preparing cDNA libraries for Illumina RNAseq, and the EMBRC-ERIC Laboratory for Low Level Trophic Interactions at NTNU SeaLab for access to the Calanus finmarchicus culture.
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 3
    Publication Date: 2022-05-26
    Description: © The Author(s), 2019. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Skottene, E., Tarrant, A. M., Olsen, A. J., Altin, D., Ostensen, M., Hansen, B. H., Choquet, M., Jenssen, B. M., & Olsen, R. E. R. The beta-oxidation pathway is downregulated during diapause termination in Calanus copepods. Scientific Reports, 9, (2019): 16686, doi: 10.1038/s41598-019-53032-5.
    Description: Calanus copepods are keystone species in marine ecosystems, mainly due to their high lipid content, which is a nutritious food source for e.g. juvenile fish. Accumulated lipids are catabolized to meet energy requirements during dormancy (diapause), which occurs during the last copepodite stage (C5). The current knowledge of lipid degradation pathways during diapause termination is limited. We characterized changes in lipid fullness and generated transcriptional profiles in C5s during termination of diapause and progression towards adulthood. Lipid fullness of C5s declined linearly during developmental progression, but more β-oxidation genes were upregulated in early C5s compared to late C5s and adults. We identified four possible master regulators of energy metabolism, which all were generally upregulated in early C5s, compared to late C5s and adults. We discovered that one of two enzymes in the carnitine shuttle is absent from the calanoid copepod lineage. Based on the geographical location of the sampling site, the field-samples were initially presumed to consist of C. finmarchicus. However, the identification of C. glacialis in some samples underlines the need for performing molecular analyses to reliably identify Calanus species. Our findings contributes to a better understanding of molecular events occurring during diapause and diapause termination in calanoid copepods.
    Description: The authors wish to thank Dept. of Biology at Norwegian University of Science and Technology (NTNU) for additional funding for Elise Skottene´s stay at Woods Hole Oceanographic Institution (WHOI), Christoffer H. Hilde for help in the field and in the lab, Siv Anina Etter, Øystein Leiknes, Sofia Soloperto and Clara Igisch for help with the field work, Justyna Świeżak and Signe D. Løvmo for experimental assistance, Hanny Rivera for help with bioinformatic analyses at WHOI. The RNA seq work was provided by the Genomics Core Facility (GCF). GCF is funded by the Faculty of Medicine and Health Sciences at NTNU and Central Norway Regional Health Authority. Ann M. Tarrant was funded by the National Science Foundation (Award Number OPP-1746087).
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 4
    Publication Date: 2022-05-26
    Description: Author Posting. © The Author(s), 2017. This is the author's version of the work. It is posted here for personal use, not for redistribution. The definitive version was published in Bucklin, Ann et al. "Population Genomics of Marine Zooplankton." Population Genomics: Marine Organisms. Ed. Om P. Rajora and Marjorie Oleksiak. Springer, 2018. doi:10.1007/13836_2017_9.
    Description: The exceptionally large population size and cosmopolitan biogeographic distribution that distinguish many – but not all – marine zooplankton species generate similarly exceptional patterns of population genetic and genomic diversity and structure. The phylogenetic diversity of zooplankton has slowed the application of population genomic approaches, due to lack of genomic resources for closelyrelated species and diversity of genomic architecture, including highly-replicated genomes of many crustaceans. Use of numerous genomic markers, especially single nucleotide polymorphisms (SNPs), is transforming our ability to analyze population genetics and connectivity of marine zooplankton, and providing new understanding and different answers than earlier analyses, which typically used mitochondrial DNA and microsatellite markers. Population genomic approaches have confirmed that, despite high dispersal potential, many zooplankton species exhibit genetic structuring among geographic populations, especially at large ocean-basin scales, and have revealed patterns and pathways of population connectivity that do not always track ocean circulation. Genomic and transcriptomic resources are critically needed to allow further examination of micro-evolution and local adaptation, including identification of genes that show evidence of selection. These new tools will also enable further examination of the significance of small-scale genetic heterogeneity of marine zooplankton, to discriminate genetic “noise” in large and patchy populations from local adaptation to environmental conditions and change.
    Description: Support was provided by the US National Science Foundation to AB and RJO (PLR-1044982) and to RJO (MCB-1613856); support to IS and MC was provided by Nord University (Norway).
    Keywords: Zooplankton ; Population genomics ; Transcriptomics ; Evolution ; Population genetics
    Repository Name: Woods Hole Open Access Server
    Type: Book chapter , Preprint
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