Exposure of first-feeding cod larvae to dispersed crude oil results in similar transcriptional and metabolic responses as food deprivation

ABSTRACT

Exposure of first-feeding cod larvae (Gadus morhua) to dispersed oil results in reduced feeding during an important transition period. First-feeding cod larvae were subjected to a 4-d treatment of food deprivation and sampled for microarray analyses. These microarray data were combined with data from cod larvae treated with mechanically and chemically dispersed oil in an attempt to understand to what extent starvation might explain some of the effects observed in first-feeding cod larvae during oil exposure. Transcriptional profiling of cod larvae suggested that the influence of oil exposure was almost as dramatic as being completely deprived of food. Protein and cellular degradation and loss of amino acids and glucose appear to be concomitant responses to both oil exposure and starvation. Fluorescence imaging of gut content indicated low uptake of food, and reduced growth (decrease in dry weight and in carbon and nitrogen content) was also noted in oil-exposed larvae, providing phenotypic anchoring of microarray data. The study displays the importance in combining use of high-throughput molecular tools with assessment of fitness-related endpoints in order to provide a greater understanding of toxicant-induced responses. This combined-approach investigation suggests that reduction of food uptake is an important process to be included when predicting effects of accidental oil spills. Finally, when comparing data from two oil treatments, exposure to chemically dispersed oil did not appear to result in greater toxicity than exposure to mechanically dispersed oil.

Funding

This project was financially supported by the Norwegian Research Council (196604/S40 and 184716). The authors thank Hui-shan Tung (NIFES) for technical help with RNA extraction and amplification. The authors also thank the following people at the Computational Biology Unit (CBU) in Bergen and the Norwegian Microarray Consortium (NMC) in Bergen for valuable help and support with developing and annotating the cod microarray, J-Express support, and ArrayExpress annotation and submission: Anders Lanzen, Kjell Pettersen, Svenn Helge Grindhaug, Rita Holdhus, Pawel Sztromwasser, and Anne-Kristin Stavrum.

Supplemental data

Supplemental data for this article can be accessed at the publisher’s website.

Additional information

Funding

This project was financially supported by the Norwegian Research Council (196604/S40 and 184716). The authors thank Hui-shan Tung (NIFES) for technical help with RNA extraction and amplification. The authors also thank the following people at the Computational Biology Unit (CBU) in Bergen and the Norwegian Microarray Consortium (NMC) in Bergen for valuable help and support with developing and annotating the cod microarray, J-Express support, and ArrayExpress annotation and submission: Anders Lanzen, Kjell Pettersen, Svenn Helge Grindhaug, Rita Holdhus, Pawel Sztromwasser, and Anne-Kristin Stavrum.