Expressed sequence tags 454 sequencing and biomineralization gene expression for pearl sac of the pearl oyster,Pinctada fucata martensii

Abstract

Pearl sac is the tissue that secretes proteins resulting into artificial pearl formation, a highly controlled biomineralization process similar to development of inner shell regulated by the mantle. We present here the pearl sac transcriptome of Pinctada fucata martensii using massively parallel pyrosequencing. A total of 21 729 putative unique transcripts were assembled and annotated. Twenty-three candidate biomineralization genes were identified, such as calmodulin, calponin-like protein (CLP), mantle gene, pearlin, nacrein and Pif. The sequence data contained 4303 potential SNP loci and 4291 probable indels, providing a resource for molecular biomarker, population genetics and gene function. Expression levels of six potential biomineralization genes were also characterized with real-time PCR. The expression level of mantle gene 4 was the highest, followed by lysine-rich matrix protein 4. Nearly all detected genes maintained the highest expression levels in mantle edge and the lowest in pearl sac. In both tissues of mantle centre and pearl sac, the six genes had an obvious higher expression activity in host oyster producing nacre pearls than those producing plain nuclei, but the expression level of CLP was similar in the two host groups. These results will notably advance biomineralization and transcript-wide study in P. fucata martensii and other Pinctada species.

Effects of replacing microalgae with an artificial diet on pearl production traits and mineralization-related gene expression in pearl oyster Pinctada fucata martensii

“…The adult pearl oysters were subjected to nucleus insertion, wherein a nucleus and a piece of graft tissue were inserted into the gonads of the oyster. The procedures for nucleus insertion operation were consistent with those reported by Gu, Huang and Wang () and Zhan, Gu and Yu (). The animals were recuperated for 30 days after the nucleus insertion and then sampled for the experiment.…”

Expression profiles of nine biomineralization genes and their relationship with pearl nacre thickness in the pearl oyster,Pinctada fucata martensiiDunker

“…; Gu, Huang, Wang, Gan, Zhan, Shi & Wang ; McGinty, Zenger, Jones & Jerry ; Masaoka, Samata, Nogawa, Baba, Aoki, Kotaki, Nakagawa, Sato, Fujiwara & Kobayashi ; Zhan et al . ). Therefore, the three tissues of ME, MC and PS are all involved in biomineralization, responsible for either shell development or pearl formation.…”

“…Moreover, many candidate biomineralization genes were screened thanks to the second generation sequencing technology (Kinoshita, Wang, Inoue, Maeyama, Okamoto, Nagai, Kondo, Hirono, Asakawa & Watabe ; Zhao, Wang, Jiao, Huang, Deng, Wang & Du ; Shi, Yu, Gu, Zhan, Wang & Wang ; Zhan et al . ). Although there were several reports concerning biomineralization gene expression level recently, their limitations are undeniable.…”

“…; Zhan et al . ). Additionally, the expression levels of several biomineralization genes were also compared during the ontogeny or among various sizes of P. fucata martensii (Miyazaki, Nishida, Aoki & Samata ; Zhang & He ).…”

“…The study of biomineralization, especially in pearl oysters, has attracted widespread research interest in recent years (Belcher, Wu, Christensen, Hansma, Stucky & Morse 1996;Falini, Albeck, Weiner & Addad 1996;Sudo, Fujikawa, Nagakura, Tanaka, Nakashima & Takahashi 1997;Suzuki, Saruwatari, Kogure, Yamamoto, Nishimura, Kato & Nagasa-wa1 2009). Such interest, on one hand, is attributed to their intriguing microstructure of shell (Zhan, Gu, Yu, Wen, Shi & Wang 2015), which consists of outer and inner parts. Although they are constructed with calcium carbonate, the outer part is made of dim calcitic prismatic layers while the inner part is made of lustrous aragonitic nacreous layers owing to different configuration of calcium carbonate (Zhan et al 2015).…”