Pinctada Research Articles

Analysis of Nutritional Composition of the Pearl Oyster Pinctada radiata as a New Mediterranean “Bioresource” for Human Consumption

Protein intake inadequacy has been considered to be one of the major nutritional problems worldwide for many years and it appears that this issue will continue to increase sharply in the coming decades. This deficiency can be partly overcome by the effective use of protein-rich bioresources such as mollusks. In the present study, the oyster Pinctada radiata, collected from the Aegean Sea, is fully nutritionally characterized as a new non-indigenous bioresource concerning mainly its protein, carbohydrate and fat composition during the different seasons of the year. The results showed that the protein content of the pearl oyster is at satisfactory levels, with its maximum value in winter and minimum in summer. On the contrary, its fat and carbohydrates are at low levels, with their maximum values in the summer period. Regarding the profile of fatty acids, polyunsaturated fats are in the highest proportion, which is very encouraging, as a diet rich in this kind of fat is desired. The entire nutritional profile of the studied oyster demonstrates its high nutritional value and supports its possible use as a “new” seafood source for human consumption in the Mediterranean.

Molecular and morphological data provide evidence for only one alien species of pearl oyster in the Mediterranean Sea

Taxonomic identification of alien bivalve species in the Mediterranean Sea can be challenging because of high morphological variability and the occurrence of cryptic species complexes, as in the case of pearl oysters. While the presence of the Lessepsian species Pinctada radiata is well-established in the eastern Mediterranean Sea, the presence of P. fucata was recently suggested based on morphological data. In this study we performed an integrative assessment based on morphological and genetic data on pearl oysters collected across the Mediterranean Basin. Molecular species delimitation and phylogenetic analyses allowed a straightforward taxonomic assignment of all collected specimens to P. radiata. These specimens show the entire suite of morphological character states considered diagnostic of either P. fucata or P. radiata by previous studies. This finding clearly demonstrates that these morphological characters have no taxonomic value, and their variability observed in specimens from the Mediterranean Sea represents (part of) the intraspecific variability of P. radiata. While no evidence has been found for the presence of P. fucata, the earlier occurrences of P. radiata from the eastern and southern Mediterranean Sea are complemented with verified occurrence in the western and northern regions, demonstrating a further spreading of this non-native species throughout the Mediterranean Sea. This study clarifies the taxonomic identification and geographical distribution of pearl oysters in the Mediterranean Sea and substantiates the importance of molecular identification of alien bivalves characterized by extensive variation in shell characters.

Effectiveness Pearl Oyster and Cucumber Sea on Bone Regeneration

Effectiveness Pearl Oyster and Cucumber Sea on Bone Regeneration

Modification of Chitosan Isolation Method from Pearl Oyster Shell (Pinctada maxima sp) as A Source of Natural Polymer

Abstract Chitosan is natural polymer with abundant availability and unique characteristics. The purpose of this study was to investigate the effects of various isolation methods on chitosan properties. Chitosan was obtained by isolation method using oyster pearl shell (Pinctada maxima sp.). The parameters of the deacetylation process are the comparison of heating method with microwave method and the comparison of microwave power. Chitosan was characterized for degree of deacetylation (DD) and functional groups by FTIR, and viscosity by Brookfield viscometer. The microwave method was faster than the heating method. Then, the larger mass of shell and %NaOH produced a higher DD of 89.75%. However, the use of 60g mass and 60% NaOH resulted in an already high DD of 81.96%. Furthermore, variation microwave power showed the highest DD at high power. FTIR spectrum analysis showed the appearance of chitosan functional groups, OH and NH2 groups. The viscosity value decreased as the microwave power increased. Based on this study, different isolation methods affect the quality of chitosan. However, it’s necessary to conduct more detailed research related to changes in chemical structure. Therefore, oyster shells can produce chitosan as a source of natural polymers with different characteristics.

Metabolic Response in the Gill Tissue of Juvenile Black-Shelled Pearl Oyster (Pinctada fucata martensii) under Salinity Stress

Salinity significantly affects shellfish metabolism and growth. In this study, we evaluated the characterization of metabolomic differences in the juvenile black-shelled pearl oyster, Pinctada fucata martensii, under 15‰ (LSG), 25‰ (CG), and 35‰ (HSG) salinity conditions. Non-targeted metabolomics analyses revealed that salinity stress altered the metabolism of pearl oyster. A total of 229 significant differential metabolites (SDMs) were identified between LSG and CG via an in-house MS2 database, 241 SDMs were identified between LSG and HSG, and 50 SDMs were identified between CG and HSG. The pathway analysis showed that 21 metabolic pathways were found between LSG and CG, such as arginine and proline metabolism, glycerophospholipid metabolism, and pentose and glucuronide interconversion. A total of 23 metabolic pathways were obtained between LSG and HSG, such as aspartate, alanine, and glutamate metabolism. Only aminoacyl-tRNA biosynthesis, cysteine and methionine metabolism, and biotin metabolism were enriched between CG and HSG. A further integrated analysis suggested that amino acid metabolism might participate in osmoregulation and energy metabolism to respond to salinity stress in P. f. martensii, and the metabolic pathways differed under varying salinity stress conditions. In addition, low salinity stress might promote apoptosis in pearl oysters. Altogether, these results clarify the salinity tolerance mechanism of pearl oysters.

Is there a case to reduce the duration of spat collector deployment for black-lip (Pinctada margaritifera) and winged (Pteria penguin) pearl oysters in the Fiji Islands?

Spat collection activities, targeting black-lip (Pinctada margaritifera) and winged (Pteria penguin) pearl oysters, support successful cultured round pearl and mabé pearl sectors in the Fiji Islands. To improve supply of pearl oysters for pearl production, a national spat collection program was developed based on standardised methodology, where commercially available spat collectors are deployed for 10–18 months. Research is now required to maximise the productivity of this program and optimising the duration of spat collector deployments is seen as a priority. This study considered whether there is justification to reduce the duration of spat collector deployments for black-lip and winged pearl oysters to less than 8 months. Spat collectors were deployed at multiple sites and then recovered after 5, 6, 7, or 8 months to examine the yield and size of resulting spat. While duration of spat collector deployment was important in determining the yield and size of harvested spat, it was not possible to generalise responses. Rather, conclusions were liable to vary over macro and micro spatial scales, depending on the target species. Such variability, coupled with the small size of spat at harvest, greatly limited the feasibility and rationale for reducing the duration of spat collector deployment to improve the supply of pearl oysters for pearl production. On this basis, we argue that there is no justification to modify the standardised methodology currently used within the national spat collection program in Fiji, where spat collectors are deployed for longer than 8 months.

Pertumbuhan tiram mutiara (Pinctada maxima) menggunakan metode karambah apung dan longline

Pearl oyster cultivation is a growing industry in various countries. The growth and quality of pearls produced by oysters is greatly influenced by the cultivation method used. This research aims to compare the growth of pearl oysters (Pinctada maxima) cultivated using the floating cage and longline methods. Different cultivation methods can influence the growth of pearl oysters and the surrounding environmental conditions. Statistical analysis was conducted on sample size, mean values, standard deviation, and standard error of the mean for both cultivation methods. The results indicate no significant difference in the growth of pearl oysters between the floating cage and longline methods. However, biofouling and other disrupting organisms can affect the growth of pearl oysters in the floating cage method. The study also highlights the importance of environmental factors such as water quality, temperature, and food availability in influencing the growth of pearl oysters. Thus, this research provides valuable insights for the pearl oyster cultivation industry in selecting the optimal cultivation method to enhance productivity and the quality of the pearls produced.

Chemical toxicity of leachates from synthetic and natural-based spat collectors on the embryo-larval development of the pearl oyster, Pinctada margaritifera

In French Polynesia, the pearl farming industry relies entirely on collecting natural spat using a shade-mesh collector, which is reported to contribute to both plastic pollution and the release of toxic chemicals. With the aim of identifying more environment-friendly collectors, this study investigates the chemical toxicity of shade-mesh (SM) and alternative materials, including reusable plates (P), a newly developed biomaterial (BioM) and Coconut coir geotextile (Coco), on the embryo-larval development of Pinctada margaritifera. Embryos were exposed during 48 h to four concentrations (0, 0.1, 10 and 100 g L-1) of leachates produced from materials. Chemical screening of raw materials and leachates was performed to assess potential relationships with the toxicity observed on D-larvae development. Compared to the other tested materials, results demonstrated lower levels of chemical pollutants in BioM and no toxic effects of its leachates at 10 g L-1. No toxicity was observed at the lowest tested concentration (0.1 g L-1). These findings offer valuable insights for promoting safer spat collector alternatives such as BioM and contribute to the sustainable development of pearl farming.

The effects of exogenous additives on the vitality of Chinese pearl oyster (Pinctada fucata) sperm under different conditions

During the artificial breeding process of Chinese pearl oysters, the quality and vitality of sperm and eggs are pivotal in determining the success rate of fertilization. This study delves into the impact of externally added fructose, glucose, and ammoniated water on sperm vitality and lifespan under varying temperature conditions. The results indicate that the addition of exogenous energy sources and cell protectants, specifically monosaccharide energy substances, significantly improves sperm vitality. Moreover, under 4°C conditions, adding 2.8 mmol/L fructose, glucose, and 2 mmol/L ammoniated water to sperm samples significantly enhances sperm vitality and prolongs their lifespan. This provides strong evidence for the feasibility of short-term preservation and vitality enhancement strategies for Chinese pearl oyster sperm and also offers important scientific support for optimizing the artificial reproduction techniques of Chinese pearl oysters.

Population Biology of the Non-Indigenous Rayed Pearl Oyster (Pinctada radiata) in the South Evoikos Gulf, Greece

Population Biology of the Non-Indigenous Rayed Pearl Oyster (Pinctada radiata) in the South Evoikos Gulf, Greece

Bycatch of Tropical Rock Oysters from Spat Collection Activities Targeting Pearl Oysters in Fiji

Bycatch of Tropical Rock Oysters from Spat Collection Activities Targeting Pearl Oysters in Fiji

RNA-Seq and metabolomic analysis reveal dynamic response mechanism to hypoxia in the pearl oyster Pinctada fucata martensii

Hypoxia is becoming a stressor in aquatic environments due to human activities and climate change. To reveal the dynamic response mechanisms of pearl oyster, this study investigated transcriptomic and metabolomic changes in pearl oyster (Pinctada fucata martensii) exposed to hypoxia for 2 and 25 days. In total, 488 differentially expressed genes (DEGs) were detected between 2 and 25 days of hypoxia stress. The identified DEGs were primarily associated with Gene Ontology (GO) terms such as "histone H4 acetylation", "DNA methylation", "histone (H3-K9/H4-K20/H3-K27/H3-K4) trimethylation", "positive regulation of ATPase activity", "myosin complex", “microtubule-based processes", "actin cytoskeleton", and "glutathione peroxidase activity", as well as KEGG pathways such as "neuroactive ligand-receptor interactions", "ECM-receptor interactions", and "apoptosis". We also identified 77 significantly differential metabolites (SDMs), which were associated with 32 metabolic pathways, including arginine and proline metabolism, glycerophospholipid metabolism, aminoacyl-tRNA biosynthesis, and sphingolipid metabolism. Integrated DEGs and SDMs analyses showed that pearl oysters were found to suffer from reduced biomineralization, hindered cytoskeletal reorganization, decreased neuronal excitability, apoptosis, immune inhibition, and oxidative stress after 25 days of hypoxic stress. Overall, these results help to elucidate the complex responses of pearl oysters to hypoxic conditions.

Spatial and temporal variability of fouling communities on oyster spat collectors at Inhaca Island Southern Mozambique: Exploring the influence on recruitment of the oysters Pinctada capensis and Saccostrea cucullata

In the transition from pelagic larva to benthic adult, larvae likely encounter a diverse assemblage of resident invertebrates in their habitat, which may also compete for space during post-settlement periods. Fouling fauna in rocky and seagrass habitats on Inhaca Island, southern Mozambique, was evaluated over 4 months in each of two seasons on oyster collectors fixed at 2 cm above the bottom. As expected, two species of oysters recruited to tiles: the rock oyster Saccostrea cucullata in rocky habitats and the pearl oyster, Pinctada capensis in seagrass habitats. The composition and density of other fouling fauna varied among habitats, location, seasons and surfaces and depending on the duration of the deployment. In seagrass habitats, oysters and barnacles were generally less abundant, allowing other taxa to have higher relative abundance, while higher density of individuals was recorded in rocky habitat. Barnacles dominate among fouling fauna on collectors in both habitats. Despite evidence consistent with negative interactions between oysters and barnacles, the effects of other fouling fauna on oyster abundance appear modest up to 4 months after tiles are placed. Overall, the results help improve our general understanding of the environmental processes that affect the colonisation of intertidal invertebrates, particularly in the southwestern Indian Ocean.

Comparison of in situ black-lipped oyster spat collection and larval dispersal modelling results in semi-closed pearl-farming lagoons of the Tuamotu Archipelago

Spat collection of the pearl oyster Pinctada margaritifera in atoll lagoons of French Polynesia is the fundamental sustain of black pearl farming. Spat collection has always yielded variable results in space and time, but obvious signs of steady decreases, even collapses, have emerged in several lagoons. Spat collection materializes the ecological connectivity pathways between wild spawning populations and the location of artificial larval settlement substrates. To assess if oyster larval dispersal modelling could capture such pathways, we compared four six-week long spat collector deployment periods with dispersal simulations in two different lagoons. Spat collectors displayed wide spatial and temporal variations. Numerical modelling and field experiments were generally not in agreement. Although both methods have limitations, they can still approximate each other. But the accuracy of model simulations cannot be ascertained with spat collection data only. Using a SWOT (Strength-Weakness-Opportunities-Threats) analysis, we emphasize the complementarity of both approaches for management decisions.

The impacts of PVC microplastics on physiology and transcriptomic responses of pearl oyster Pinctada fucata martensii

The impacts of PVC microplastics on physiology and transcriptomic responses of pearl oyster Pinctada fucata martensii

Reproductive Biology of Pearl Oyster (Pinctada radiata, Leach 1814) Based on Microscopic and Macroscopic Assessment of Both Sexes in the Eastern Mediterranean (South Evia Island)

Reproductive Biology of Pearl Oyster (Pinctada radiata, Leach 1814) Based on Microscopic and Macroscopic Assessment of Both Sexes in the Eastern Mediterranean (South Evia Island)

Comparative transcriptomics identifies genes underlying growth performance of the Pacific black-lipped pearl oyster Pinctada margaritifera

BackgroundIn bivalves, the rate at which organisms grow is a major functional trait underlying many aspects of their commercial production. Growth is a highly polygenic trait, which is typically regulated by many genes with small to moderate effects. Due to its complexity, growth variability in such shellfish remains poorly understood. In this study, we aimed to investigate differential gene expression among spat of the pearl oyster Pinctada margaritifera with distinct growth phenotypes.ResultsWe selected two groups of P. margaritifera spat belonging to the same F2 cohort based on their growth performance at 5.5 months old. Transcriptome profile analysis identified a total of 394 differentially expressed genes between these Fast-growing (F) and Slow-growing (S) phenotypes. According to functional enrichment analysis, S oysters overexpressed genes associated with stress-pathways and regulation of innate immune responses. In contrast, F oysters up-regulated genes associated with cytoskeleton activity, cell proliferation, and apoptosis. Analysis of genome polymorphism identified 16 single nucleotide polymorphisms (SNPs) significantly associated with the growth phenotypes. SNP effect categorization revealed one SNP identified for high effect and annotated for a stop codon gained mutation. Interestingly, this SNP is located within a gene annotated for scavenger receptor class F member 1 (SRF1), which is known to modulate apoptosis. Our analyses also revealed that all F oysters showed up-regulation for this gene and were homozygous for the stop-codon mutation. Conversely, S oysters had a heterozygous genotype and a reduced expression of this gene.ConclusionsAltogether, our findings suggest that differences in growth among the same oyster cohort may be explained by contrasted metabolic allocation between regulatory pathways for growth and the immune system. This study provides a valuable contribution towards our understanding of the molecular components associated with growth performance in the pearl oyster P. margaritifera and bivalves in general.

Genomic and transcriptomic analysis to investigate the growth heterosis mechanisms of pearl oysters (Pinctada fucata martensii)

Pinctada fucata martensii, a bivalve mollusk highly valued for seawater pearl production, exhibits growth traits crucial for pearl yield and quality. Although hybridization promotes growth, the mechanisms underlying growth heterosis in pearl oysters remain unclear. This study utilized two inbred populations (PB and PY) and one hybrid population (F) constructed from pearl oysters. Comparative analysis of growth traits, along with whole-genome sequencing (WGS) and RNA sequencing (RNA-seq), revealed that hybrid F showed superior growth traits. Compared with the parents, hybrid F exhibited significant heterosis for shell height (10.422%), shell length (11.361%), shell width (11.411%), and total weight (36.254%). Analysis of population genetic structure indicated increased heterozygosity in hybrid F through hybridization. Expression pattern analysis revealed that approximately 93.79% of the DEGs displayed dominant expression, with approximately 6.21% exhibited overdominant, indicating pivotal roles of dominant genes in heterosis development. There were more paternal dominant genes than maternal genes, suggesting that paternal genetic information significantly impacts heterosis in hybrid F. Furthermore, selective sweep and expression pattern analyses revealed that immune defense, metabolism, and regulatory processes are correlated with hybrid phenotypic growth traits in pearl oysters. In conclusion, this study explored the molecular mechanisms that influence the hybrid growth advantage of pearl oysters, with the aim of providing valuable insights and ideas for breeding research in aquaculture.

Biomineral photonic materials with a gradient structure: The ligament of the pearl oyster Pinctada margaritifera

The bivalve fibrous ligaments (FLs) are unusual biomineralized materials evolved to open two shell valves as needed. For a long time, the inside beautiful structural colors of the FLs have received little attention. Here, using optical microscopy, SEM, and fiber optic spectrometry combined with the image processing method and pair correlation function (Pcf) analysis, we investigate the structure and optical property of the FL of the pearl oyster Pinctada margaritifera. In this FL, we find that: (1) the aragonite fibers are uniform in diameter with an average of 98 ± 10 nm; (2) they are spatially organized with short-range order; and (3) they vary gradiently in their nearest-neighbor distance (d) from 148 nm to 103 nm along the lateral-inner direction of the FL. Therefore, this FL possesses a 2D amorphous gradient photonic structure, which results in that the FL displays extremely variable structural colors spanning from blue to yellow. In short, this work provides a new model of biological photonic structure, which may inspire the design and synthesis of novel photonic materials.

Inhibitors of LAMP used to detect Tenacibaculum sp. strain Pbs-1 associated with black-spot shell disease in Akoya pearl oysters, and additives to reduce the effect of the inhibitors

Black-spot shell disease is an unresolved disease that decreases pearl quality and threatens pearl oyster survival. In previous studies, the bacterium Tenacibaculum sp. strain Pbs-1 was isolated from diseased Akoya pearl oysters Pinctada fucata, and a rapid, specific, and sensitive loop-mediated isothermal amplification (LAMP) assay for detecting this pathogen was established. This technology has considerable potential for routine diagnosis of strain Pbs-1 in oyster hatcheries and/or pearl farms; therefore, it is vital to identify substances in environmental samples that might inhibit LAMP and to find additives that can reduce the inhibition. In this study, we investigated the effects of six chemicals or proteins, otherwise known as conventional PCR inhibitors, on LAMP, using the DNA of strain Pbs-1 as template: humic acid, urea, iron (III) chloride hexahydrate, melanin, myoglobin, and Ethylenediamine-N,N,N′,N′-tetraacetic acid, disodium salt, dihydrate (EDTA; pH 6.5). Next, to reduce the effects of identified inhibitors, we tested the addition of bovine serum albumin (BSA) or T4 gene 32 protein (gp32) to the LAMP assay. When 50 ng of DNA template was used, 4 ng/μL of humic acid, 0.05% melanin, and 10 mM of EDTA (pH 6.5) inhibited the LAMP reaction, whereas myoglobin, urea, and FeCl3 had no effect. When 50 pg of DNA template was used, 4 ng/μL of humic acid, 0.05% melanin, 4 μg/μL of myoglobin, 10 μg/μL of urea, and 10 mM of EDTA inhibited the LAMP reaction. Thus, it was shown that the gene-amplification inhibitory effect of melanin, humic acid, and urea could be reduced by adding BSA or gp32 to the LAMP reaction mixture. This technique could be applied as part of a protocol to prevent mass mortalities of pearl oysters; moreover, the results enhance our knowledge about substances that inhibit LAMP and methods to reduce the inhibition, which have rarely been reported.