Transcriptional profiling of reproductive development, lipid storage and molting throughout the last juvenile stage of the marine copepod Calanus finmarchicusReport as inadecuate




Transcriptional profiling of reproductive development, lipid storage and molting throughout the last juvenile stage of the marine copepod Calanus finmarchicus - Download this document for free, or read online. Document in PDF available to download.

Frontiers in Zoology

, 11:91

First Online: 16 December 2014Received: 23 July 2014Accepted: 01 December 2014

Abstract

IntroductionCalanus finmarchicus, a highly abundant copepod that is an important primary consumer in North Atlantic ecosystems, has a flexible life history in which copepods in the last juvenile developmental stage fifth copepodid, C5 may either delay maturation and enter diapause or molt directly into adults. The factors that regulate this developmental plasticity are poorly understood, and few tools have been developed to assess the physiological condition of individual copepods.

ResultsWe sampled a cultured population of C. finmarchicus copepods daily throughout the C5 stage and assessed molt stage progression, gonad development and lipid storage. We used high-throughput sequencing to identify genes that were differentially expressed during progression through the molt stage and then used qPCR to profile daily expression of individual genes. Based on expression profiles of twelve genes, samples were statistically clustered into three groups: 1 an early period occurring prior to separation of the cuticle from the epidermis apolysis when expression of genes associated with lipid synthesis and transport FABP and ELOV and two nuclear receptors ERR and HR78 was highest, 2 a middle period of rapid change in both gene expression and physiological condition, including local minima and maxima in several nuclear receptors FTZ-F1, HR38b, and EcR, and 3 a late period when gonads were differentiated and expression of genes associated with molting Torso-like, HR38a peaked. The ratio of Torso-like to HR38b strongly differentiated the early and late groups.

ConclusionsThis study provides the first dynamic profiles of gene expression anchored with morphological markers of lipid accumulation, development and gonad maturation throughout a copepod molt cycle. Transcriptomic profiling revealed significant changes over the molt cycle in genes with presumed roles in lipid synthesis, molt regulation and gonad development, suggestive of a coupling of these processes in Calanus finmarchicus. Finally, we identified gene expression profiles that strongly differentiate between early and late development within the C5 copepodid stage. We anticipate that these findings and continued development of robust gene expression biomarkers that distinguish between diapause preparation and continuous development will ultimately enable novel studies of the intrinsic and extrinsic factors that govern diapause initiation in Calanus finmarchicus.

KeywordsArthropod Crustacean Gene expression Molt cycle Transcriptomics AbbreviationsBpBase-pair

C4 and C5Fourth and fifth copepodid stage, respectively

cDNAComplementary DNA

CPMCounts per million

DNADeoxyribonucleic acid

EcREcdysone receptor

EF-1αElongation factor 1 alpha

ELOVElongation of very long-chain fatty acids

ERREstrogen-related receptor

FABPFatty acid binding protein

FDRFalse discovery rate

FPKMFragments per feature kilobase per million reads mapped

FTZ-F1Fushi tarazu transcription factor 1

GOGene ontology

HRHormone receptor e.g., HR38: hormone receptor 38

nrNon-redundant database

PCAPrinciple component analysis

PCRPolymerase chain reaction

qPCRQuantitative PCR

RNARibonucleic acid

RXRRetinoid-x-receptor

SNPSnurportin

TMMTrimmed mean of M-values

TSGTumor suppressor gene

VtgVitellogenin

Electronic supplementary materialThe online version of this article doi:10.1186-s12983-014-0091-8 contains supplementary material, which is available to authorized users.

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Author: Ann M Tarrant - Mark F Baumgartner - Bjørn Henrik Hansen - Dag Altin - Trond Nordtug - Anders J Olsen

Source: https://link.springer.com/



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