Post-diapause transcriptomic restarts: insight from a high-latitude copepod.

Area of Science:

• Marine Biology
• Developmental Biology
• Molecular Biology

Background:

• Diapause is a crucial survival strategy for many organisms, enabling them to endure unfavorable environmental conditions.
• The transition from diapause to active development involves complex physiological and molecular changes that are not yet fully understood.
• Neocalanus flemingeri, a key zooplankter in the North Pacific, utilizes diapause to survive and time reproduction, making it an important model for this study.

Purpose of the Study:

• To characterize the molecular mechanisms regulating the transition from diapause to post-diapause in Neocalanus flemingeri.
• To identify the key transcriptional changes that occur during the termination of diapause.
• To understand how these changes initiate post-diapause development and reproduction.

Main Methods:

• Transcriptional profiling of diapausing Neocalanus flemingeri females over a two-week time series.
• Collection of females from deep waters (>400m) to ensure a diapausing state.
• Analysis of gene expression changes in response to a diapause termination stimulus.

Main Results:

• A rapid transcriptional switch from diapause to post-diapause profiles occurred within 12 hours of stimulus, despite low temperatures (5-6°C).
• Early transcriptional changes (within 1 hour) involved up-regulation of genes in the 20E cascade, TCA cycle, and RNA metabolism, alongside down-regulation of chromatin silencing genes.
• By 12 hours, genes related to cell division, differentiation, and development were upregulated, and by seven days, oogenesis and energy metabolism genes were activated, indicating full reproductive program initiation.

Conclusions:

• The transition from diapause to post-diapause involves a highly structured and rapid sequence of transcriptional events.
• These molecular changes orchestrate the activation of biological processes necessary for successful reproduction.
• The findings propose potentially universal mechanisms for diapause termination across different organisms.