Differential gene expression in diapausing and active Calanus finmarchicus (Copepoda)

Abstract

To survive long periods of low food availability, some calanoid copepods have a life history that includes a diapause phase during which copepodids delay development to adulthood, migrate to depth, reduce metabolism, and utilize stored lipids for nourishment. While seasonal patterns in diapause have been described, the environmental and physiological regulation of diapause has not been elucidated. We collected Calanus finmarchicus C5 copepodids from surface (0 to 39 m) and deep (157 to 201 m) waters in the Gulf of Maine, and both morphological and biochemical measurements indicated that these copepodids were from active and diapausing populations, respectively. Two complementary molecular techniques were used to compare gene expression in these 2 groups: (1) suppressive subtractive hybridization (SSH) was used to identify genes that may be differentially expressed, and (2) quantitative real-time RT-PCR was used to characterize patterns of gene expression in individual copepodids. Three genes associated with lipid synthesis, transport and storage (ELOV, FABP, RDH) were upregulated (more highly expressed) in active copepods, particularly those with small oil sacs. Expression of ferritin was greater in diapausing copepods with large oil sacs, consistent with a role of ferritin in chelating metals to protect cells from oxidative stress and/or delay development. Ecdysteroid receptor (EcR) expression was greater in diapausing copepods, highlighting the need for further investigation into endocrine regulation of copepod development. This study represents the first molecular characterization of gene expression associated with calanoid copepod diapause and provides a foundation for future investigations of the underlying mechanisms that regulate diapause. 355: 193-207, 2008 result of this build-up of lipids, copepods with this life history strategy are an extremely nutritious food source for their predators. Thus, the environmental and physiological factors that control development and, in particular, diapause, have important implications for marine ecosystem processes. KEY WORDS: Diapause · Copepod · Calanus finmarchicus · Subtractive hybridization · Gene expression · Gulf of Maine Resale or republication not permitted without written consent of the publisherMar Ecol Prog SerThe environmental signals and internal biological processes that regulate diapause in calanoid copepods are unknown, and experimental studies remain difficult because copepods do not reliably enter diapause in the laboratory. In the field, investigators have relied on a suite of behavioral, morphological, and biochemical characteristics to distinguish between diapausing and active copepodids. The hallmarks of diapause are a deep distribution (within 50 to 100 m of the bottom in neritic environments and below 200 to 300 m in oceanic waters (Sameoto & Herman 1990, Miller et al. 1991, Dale et al. 1999, Heath et al. 2004), predominance of a single stage (Heath et al. 2004), torpor (Hirche 1983), empty guts with reduced epithelium (Hallberg ...

Diel vertical migration behavior of Calanus finmarchicus and its influence on right and sei whale occurrence

“…All oil-sac volumes were log-transformed prior to statistical analysis. A prosome length threshold of 2.1 mm was used to distinguish between copepodid stages CIV (< 2.1 mm) and CV (≥2.1 mm) in the VPR images (Campbell et al 2001a, Tarrant et al 2008 (Fig. 2c), and prosome length, width, and oil-sac volume were measured and derived in a manner identical to that for the VPR (Fig.…”

“…laying flat on its side). Oil-sac volume was then estimated from the oil-sac outline using methods adapted from Miller et al (2000) and described in Tarrant et al (2008). All oil-sac volumes were log-transformed prior to statistical analysis.…”

Contrasting transcriptome response to thermal stress in two key zooplankton species, Calanus finmarchicus and C. glacialis

“…In addition, as reference genes for Calanus during temperature stress have not been reported, 5 genes were tested as putative reference genes for C. finmarchicus and C. glacialis during STS and LTS. Genes cdc42, eif1ax and trx-2 were selected for their stable transcript counts in all libraries, and efa1α and 16S rRNA were selected from the literature on gene expression in C. finmarchicus (Tarrant et al 2008, Hansen et al 2013. Reciprocal BLAST searches (MegaBLAST in Geneious 7.1.0 [Biomatters], default settings) were performed between the 2 species to identify homologous genes.…”

Altered gene expression associated with epizootic shell disease in the American lobster, Homarus americanus

“…Double-stranded complementary DNA (cDNA) was synthesized from 1 g of each of these two RNA samples using the Super SMART PCR cDNA Synthesis Kit (Clontech), according to the manufacturer's instructions. Suppressive subtractive hybridization was conducted in both directions using the PCR-select cDNA subtraction kit (Clontech) as described previously [20]. Clones were ligated into pGEM-T easy (Promega) and sequenced.…”