The Distribution of Ferritins in Marine Copepods

Abstract

Iron is an essential element for the functioning of cellular processes. Ferritins, the major intracellular iron storage proteins, convert the free Fe2+ into the nontoxic Fe3+ which can be stored and transported where needed. To date, little is known about the iron metabolism in copepods; however, in these crustaceans, ferritins have been used as biomarkers of stress and diapause. A limiting factor of these studies has been the use of a single ferritin transcript as a biomarker. In this paper, we in silico mined the publicly available copepod transcriptomes to characterize the multiplicity of the ferritin transcripts in different orders and families. We also examined the expression of ferritin in three ecologically important copepods—Calanus finmarchicus, C. helgolandicus and Temora stylifera—during development and under stress conditions. A full-length transcript encoding ferritin heavy chain has been identified in all 27 mined transcriptomes, with 50% of the species possessing multiple transcripts. Ferritin expression increased in C. finmarchicus during the early–late development transition, and in T. stylifera females exposed to oxylipins at sea. Overall, our results suggest that copepod ferritins can be involved in iron storage, larval development and stress response, thus representing potential biomarker genes for ocean health status monitoring.

Folate-Mediated One-Carbon Metabolism in the Crustacean Copepod Calanus finmarchicus: Identification of Transcripts and Relative Expression across Development

“…Planktonic copepods play an important role in regulating global biogeochemical cycles [37] and serve as the key link between the lower and higher trophic levels, supporting fishery production in the early stages of life [38]. In recent years, efforts have been made to identify genes that could be potential indicators of the physiological state of copepods [23,25]. The use of these biomarkers to assess the "health" of a marine organism is useful to understand environmental adaptations (e.g., responses to starvation and stress) that can be used on a broader scale to assess changes and make predictions at population and community levels.…”

“…Despite their global importance, there is only one published whole-genome assembly for a calanoid copepod Eurytemora carolleeae (formerly E. affinis) [39] and five mitochondrial genomes within the genus Calanus (National Center for Biotechnology). In recent years, the availability of several Calanus transcriptomes has improved the characterization of many gene families, expanding the potential to better understand copepod physiology [15,[17][18][19][20][21]23,25,26]. Here, following this ongoing effort, we have focused on the identification of the transcripts encoding proteins involved in the folate and methionine cycles in Calanus finmarchicus, the biomass-dominant zooplankton in much of the North Atlantic.…”

“…Searches for putative transcripts encoding enzymes involved in the folate and methionine cycles in C. finmarchicus were performed using a well-established vetting workflow that included a transcriptome mining step, a reciprocal BLAST step to confirm protein identity, and a protein structural domain step [25,26]. Based on the reference literature, we searched a total of 12 and six enzymes, respectively, in the folate and methionine cycles (see Figure 1).…”

“…In recent decades, the availability of high-quality molecular resources (e.g., mitochondrial genomes and transcriptomes) for this copepod has enabled the characterization of genes involved in key processes such as diapause, oogenesis, lipid metabolism, and detoxification pathways [15][16][17][18][19]. Furthermore, for genes involved in neurochemical signaling systems [20,21], photoreception [22], chemical communication (chemosensory related genes) [23], and detoxification [17,24,25], relative expression across different stages of development has also been characterized, allowing the prediction of their potential function in this copepod. Here, using a well-established in silico workflow, we mined the high-quality C. finmarchicus reference transcriptome [16] to identify transcripts encoding enzymes involved in the folate and methionine cycles.…”

Ecology of Marine Zooplankton

“…The iron metabolism in copepods is investigated in Roncalli et al [17]. Attention is focused on identifying transcripts encoding ferritin, a highly conserved and ubiquitous multimeric iron storage protein required for the maintenance of iron homeostasis.…”