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Abstract Late developmental stages of the marine copepods in the genusCalanuscan 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 inCalanuscopepods. 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 inC. 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 inC. 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.
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Experimental analysis of development, lipid accumulation and gene expression in a high-latitude marine copepod
Abstract The high-latitude copepod Neocalanus flemingeri exploits the spring phytoplankton bloom to accumulate lipids for survival during food-limited periods and to fuel reproduction. At some point during development, lipid-accumulation ends and pre-adults molt into adults, descend to depth and enter a state of dormancy termed diapause. How and when they determine to make this transition is still unresolved. According to one hypothesis, the trigger is their attaining a threshold amount of lipid fullness. Alternatively, they might follow a genetic program, entering diapause within a narrow developmental window. To better understand the decision, a 5-week laboratory experiment was conducted to assess the effect of food quantity and type on lipid accumulation, biomass and gene expression in N. flemingeri copepodite stage CV. In fed individuals, the initial rate of lipid accumulation slowed by week 5, as a portion of CVs began to molt into adults. While changes in gene expression common to all fed individuals between weeks 1 and 3 were consistent with a developmental program, the duration of the CV stage was variable. Unfed individuals maintained lipid stores initially, suggesting physiological acclimatization to conserve energy. A comparison with gene expression profiles of field-collected individuals suggests similar responses to resources in the environment.
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- Award ID(s):
- 1756767
- PAR ID:
- 10473694
- Publisher / Repository:
- Oxford University Press
- Date Published:
- Journal Name:
- Journal of Plankton Research
- Volume:
- 45
- Issue:
- 6
- ISSN:
- 0142-7873
- Format(s):
- Medium: X Size: p. 885-898
- Size(s):
- p. 885-898
- Sponsoring Org:
- National Science Foundation
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