Meeting Abstract
In highly-seasonal and food-limited environments, life histories have evolved strategies to synchronize growth and reproduction to peaks in production. Diapause is a type of dormancy that ensures survival during periods of extreme cold and energy-poor conditions. The adult female of the subarctic copepod Neocalanus flemingeri enters a period of diapause prior to spawning seven to eight months later. As a capital breeder N. flemingeri depends on a short annual phytoplankton bloom to acquire and store the energetic resources to support both diapause and the reproductive program. Gene expression profiling was used to investigate the relationships between energy utilization, cellular maintenance and oogenesis in N. flemingeri . The transition from diapause to egg release was characterized by the sequential up- and down-regulation of genes involved in cellular maintenance and metabolic pathways. Timing of three major transitions in transcriptional patterns coincided with emergence from diapause and early oogenesis, mid to late oogenesis, and finally spawning and end-of-life. The down-regulation of genes involved in cellular homeostasis occurred in parallel with the up-regulation of genes related to mid-late oogenesis and protein degradation. As females began spawning, genes involved in protein ubiquitination and programmed cell death became up-regulated. The data suggest that females match fecundity to available resources by limiting germline development to early post-diapause coincident with the up-regulation of genes involved in cellular homeostasis, glycolysis and lipid catabolism. This strategy decreases the risk of reproductive failure by assuring that all oogonia can mature successfully.
