Optimal age of the donor graft tissue in relation to cultured pearl phenotypes in the mollusc, Pinctada margaritifera

Abstract

Ageing is defined as the progressive decline in tissue and organ functions over time. This study aims to evaluate the ageing effect on cultured pearl quality phenotypes (including size and quality traits) in the graft-recipient animal model: Pinctada margaritifera. For this, eight uniform grafting experiments were designed using two hatchery-produced pearl oyster families as donors, which were followed through time, between 7 and 30 months in age. For each age category, 20 donors were studied for each culture site giving a total of 2400 grafted oysters. Several phenotypic measurements were made: 1) donor family growth performance from shell size records, 2) pearl size and corresponding quality traits, and 3) expression of some genes related to biomineralization processes on both the mantle graft and on pearl sac tissues. Results showed that: 1) donor age has an impact on pearl size, with grafts coming from the youngest donors yielding the biggest pearls; and 2) grafts from donors between 12 and 18 months in age produced pearls of the highest quality (grade and surface quality), a result supported by an analysis where the level of expression for a panel of genes associated with biomineralization was greatest in donors within the 12 to 18 months age group. These results indicate that donors aged between 12 and 18 months have high potential for biomineralisation and nacre deposition, and likely produce larger and higher quality cultured pearls than older donors.

Whole transcriptome sequencing and biomineralization gene architecture associated with cultured pearl quality traits in the pearl oyster, Pinctada margaritifera

“…RT-qPCR was used to validate the expression patterns in the pearl sac, observed in RNA-seq, for key genes commonly used as markers of pearl quality traits, namely pif-177 , aspein, shematrin-9 and the mantle protein 10 (MP10). DNAse tratment of total RNA, cDNA sunthesis and amplification procedure has been publised previously [19].…”

“…A recent study in P. margaritifera , based on controlled bi-parental crosses and the F1 generation, demonstrated heritability ( h 2 from 0.21 to 0.37) for nacre weight and thickness, pigmentation darkness and colour, surface defects and grade, signifying a donor oyster effect with a genetic basis, although there were also important interaction components [10]. Previous studies reported that location, temperature and food availability [11–13], pearl rotation [14], donor oyster genotype [4, 9, 15–18], age [19], position of graft mantle [20] and contamination during the graft operation and/or graft operator skills [21] are all determinants of final pearl quality and do not necessarily affect similar traits.…”

Influence of Age on Pearl Production Performance, Enzymatic Activity, and Immune‐Related Gene Expression of the Pearl Oyster Pinctada fucata martensii

“…Blay et al. () also reported that the age of the donor oyster influenced the pearl size, with results showing that mantle tissues from young donors (12 and 18 months of age) produced the biggest pearls with the highest quality (grade and luster), which was buttressed by the high expression level of biomineralization genes in the younger donors. These findings correspond to the results from the current study, which analyzed biomineralization genes in 1.5‐ and 2.5‐year‐old oysters and recorded significantly higher expression levels of Pearlin * and Nacrein * in the younger oysters.…”

“…Pearlin is a matrix protein between aragonites that is involved with the development of the nacre layer by moving Ca² + to the nucleus (Montagnani et al 2011). Donor age has been reported to affect the mRNA expression of aragonite-related genes (Pif-177*, MSI60*, and Pearlin*), calcite-related genes (Aspein*, Shema-trin5*, and Prismalin*), and the gene involved in developing the nacre and prismatic layers (Nacrein*) of the pearl sac (Blay et al 2018). The increase in nacre accumulation equaled 7.2 μm/d within the second year and declined with age, attaining an average value of 3.1 μm/d (Pouvreau et al 2000).…”

How cultured pearls acquire their colour

“…Pearls are biomineralized products of shellfish species like pearl oysters and mussels. Pearl oysters are marine organisms mainly cultivated for pearl production with a vast array of species such as Pinctada margaritifera , Pteria penguin , Pinctada fucata martensii and Pinctada maxima (Blay, Planes, & Ky, 2018; Southgate, Lucas, & Saucedo, 2008). Pearl oyster P. fucata martensii is used to produce pearls with size of 4.5–8.5 mm, while P. maxima and P. margaritifera mostly produce large sized pearls (>10 mm).…”