|Ann M. Tarrant, Mark F. Baumgartner, Tim Verslycke, and Catherine L. Johnson, |
Molecular and morphological characterization of diapausing and active marine copepods, Marine Ecology Progress Series, 2008
To survive long periods of low food availability, the life history of some calanoid copepods 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 finmarchicusC5 copepodids from surface (0-39 m) and deep (157-201 m) waters in theGulf ofMaine, 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 two groups: (1) suppressive subtractive hybridization 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 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 protecting lipids from oxidative damage. 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.