Differential Gene Expression during Larval Metamorphic Development in the Pearl Oyster,Pinctada fucata, Based on Transcriptome Analysis

Abstract

P. fucata experiences a series of transformations in appearance, from swimming larvae to sessile juveniles, during which significant changes in gene expression likely occur. Thus, P. fucata could be an ideal model in which to study the molecular mechanisms of larval metamorphosis during development in invertebrates. To study the molecular driving force behind metamorphic development in larvae of P. fucata, transcriptomes of five larval stages (trochophore, D-shape, umbonal, eyespots, and spats) were sequenced using an Illumina HiSeq™ 2000 system and assembled and characterized with the transcripts of six tissues. As a result, a total of 174,126 unique transcripts were assembled and 60,999 were annotated. The number of unigenes varied among the five larval stages. Expression profiles were distinctly different between trochophore, D-shape, umbonal, eyespots, and spats larvae. As a result, 29 expression trends were sorted, of which eight were significant. Among others, 80 development-related, differentially expressed unigenes (DEGs) were identified, of which the majority were homeobox-containing genes. Most DEGs occurred among trochophore, D-shaped, and UES (umbonal, eyespots, and spats) larvae as verified by qPCR. Principal component analysis (PCA) also revealed significant differences in expression among trochophore, D-shaped, and UES larvae with ten transcripts identified but no matching annotations.

Understanding the mechanisms involved in the high sensitivity of Pecten maximus larvae to aeration

“…The database that had the most sequence similarities with P. maximus assembled transcripts was Ensembl C. gigas, which provided a putative function for 27 842 contigs (35%). While available data on larval transcriptomes remains scarce, the total number of contigs assembled and the annotation percentages were similar to those reported recently for other bivalve tissues (Li et al 2016;Li et al 2017;Mun et al 2017).…”

The nature and perception of environmental cues that orchestrate the pelago-benthic life cycle in the sponge Amphimedon queenslandica: molecular and behavioural perspectives

“…Although larval life can be a time of greatly reduced transcriptional activity , it is becoming increasingly apparent that widespread transcriptional changes do occur throughout the course of larval development. This has been demonstrated now in the abalone Haliotis asinina (Jackson et al, 2005;, polychaete Capitella teleta (Burns and Pechenik, 2017), pearl oyster Pinctada fucata (Li et al, 2016), coral Acropora millepora and sponge Amphimedon queenslandica (Conaco et al, 2012), which is consistent with the findings presented in this dissertation. These studies thus demonstrate strong support for the importance of transcriptome data to compliment pharmacological manipulation experiments and identify candidate genes for underlying the acquisition of larval competence.…”

“…For example, individual larvae of the abalone Haliotis asinina do not develop competence at the same rate (Jackson et al, 2012) and the acquisition of competence is also accompanied by significant changes in gene expression (Jackson et al, 2005;; . Indeed, there is also extensive and diverse gene activity associated with acquisition of competence in the polychaete Capitella teleta (Burns and Pechenik, 2017), pearl oyster Pinctada fucata (Li et al, 2016), coral Acropora millepora (Strader et al, 2018) and the sponge Amphimedon queenslandica (Conaco et al, 2012;Chapter 3). Therefore, transcriptional variability may fuel intra-population variation in the time to acquire competence, and thus pelagic larval duration, but the molecular mechanisms underlying this remain largely unexplored.…”

“…However, only a handful of genome-wide gene expression datasets include multiple stages throughout a time course of larval development, representing the gastropod Rapana venosa (Song et al, 2016), pearl oyster Pinctada fucata (Li et al, 2016) and coral A. millepora (Strader et al, 2018); but all of these have been conducted on pooled, not individual, larvae.…”

Characterization of pinctada fucata mantle gene 2 (pfmg2) in pearl oyster

“…Investigation of this process will provide detailed insight into the steps of shell formation. Several genes have been reported to be important for this process [5,[10][11][12][13][14][15][16]. In P. fucata, MSI31 and MSI60, rich in Gly and Ala, are reported to be framework proteins for the formation of CaCO 3 crystals [4,17].…”