Search Results (8)

The accumulation of cadmium (Cd) and microplastics (MPs) can have major deleterious effects on the health of marine ecosystems and organisms, including the pearl oyster Pinctada fucata martensii. Here, we characterized the effects of Cd and MPs on key biochemical parameters of P. f. martensii via an experiment with various treatments. Pearl oysters were exposed to either only Cd (5 or 50 μg/L), only MPs (5 mg/L), or both Cd and MPs for 2 d, and this was followed by a 5-day recovery period. Measurements of the activities of lipase, amylase, protease, T-ATPase, catalase, glutathione peroxidase, acid phosphatase, and alkaline phosphatase enzymes, as well as the malondialdehyde content in the hepatopancreas, were made at various time points during the experiment. Metabolomics analysis of the gills was also performed. Significant interactions between time and treatment on lipase, protease, and catalase activities were observed. However, no significant effect of time–treatment interactions on amylase and T-ATPase activities was observed. Enzyme activities varied among groups both during the exposure period (6 to 48 h) and the recovery period. The malondialdehyde content was also increased throughout the experiment. Pathway analysis indicated that the purine metabolism, glycerophospholipid metabolism, nucleotide metabolism, arachidonic acid metabolism, neuroactive ligand–receptor interaction, and linoleic acid metabolism pathways were the most commonly affected under different treatments. The findings of our study revealed the differential effects of exposure time and treatment on enzyme activities and metabolites and their respective pathways. Our findings enhance our understanding of the biochemical responses of the pearl oyster P. f. martensii to environmental stressors, particularly Cd and MPs. Full article

Background: In recent years, titanium dioxide (TiO₂) nanoparticles (NPs) have been widely used in various industries due to their favorable chemical properties, and their contamination of the environment has attracted much attention, especially to aquatic animals. Methods: Therefore, we assessed the impact of TiO₂ NPs (5 mg/L) on the marine bivalve, pearl oyster (Pinctada fucata martensii), especially gill metabolism. Pearl oysters were exposed to seawater containing 5 mg/L TiO₂ NPs for 14 days, followed by 7 days of recovery in untreated seawater. Gill tissues and hepatopancreatic tissues were sampled on days 0, 14, and 21 of the experiment named C0, E14, and R7, respectively. Results: Metabolomic analysis identified 102 significantly different metabolites (SDMs) on gills tissue in pearl oysters following exposure to TiO₂ NPs (C0 vs. E14). Compared with group C0, group E14 had 76 SDMs (such as acetylcholine, itaconic acid, citric acid, and taurine) with higher concentrations and 26 (including L-arginine and isobutyryl-L-carnitine) with lower concentrations. KEGG (Kyoto Encyclopedia of Genes and Genomes) analysis showed that these SDMs enriched 28 pathways, including glycine, serine, and threonine metabolism, neuroactive ligand–receptor interaction, and taurine and hypotaurine metabolism. In addition, 116 SDMs were identified in E14 and R7 pearl oysters. Compared with group E14, group R7 had 74 metabolites (such as acetylcholine, 6-phosphogluconic acid, isocitric acid, and itaconic acid) with higher concentrations and 42 (including uracil, glycerophosphocholine, N-Acetyl-D-glucosamine) with lower concentrations. The SDMs identified between E14 and R7 enriched 25 pathways, including the pentose phosphate pathway, glutathione metabolism, and citrate cycle (TCA cycle). In addition, analysis of the energy metabolism-associated enzymes revealed that exposure to TiO₂ NPs reduced Ca²⁺/Mg²⁺-ATPase, Na⁺/K⁺-ATPase, and Total-ATPase activities. Conclusions: These findings suggested that TiO₂ NPs may inhibit the energy metabolism function of gill and hepatopancreas of pearl oysters. Meanwhile, TiO₂ NPs may affect the normal functioning of immune and osmoregulatory functions of pearl oysters gill and even may lead to oxidative stress and neurotoxicity. Therefore, this study may provide a reference for analyzing the bioadaptation of marine bivalves to TiO₂ NPs and the potential negative effects of TiO₂ NPs on bivalves. Full article

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. Full article

Ammonium (NH₄⁺) plays a crucial role in the reproductive processes of key biotic groups in aquatic ecosystems—bivalves. This study aims to elucidate the effects of three different ammonium ion concentrations on sperm vitality, swimming kinematics, and morphology of Mimachlamys nobilis, Pinctada fucata martensii, and Saccostrea mordax. The results indicate that the sperm vitality and motility rates of M.nobilis and S. mordax are inversely proportional to the ammonium concentration, especially in the treatment group with an ammonium concentration of 3 mmol/L, where the decrease in sperm vitality and motility is most significant. In contrast, the sperm of P. fucata martensii reacted differently to increasing ammonium concentrations. After the addition of 2 mmol/L of ammonium, the sperm vitality and motility of P. fucata martensii reached a peak, showing a significant stimulatory effect. Additionally, as the ammonium concentration increased, the curling of the sperm flagella in M.nobilis and S. mordax increased. However, sperm flagella curling in P. fucata martensii showed no change compared to the control group. This study provides insights into the effects of ammonium concentrations on the sperm vitality and motility of three marine bivalve species and highlights the importance of sperm flagella curling as a factor affecting sperm. Full article

Recently, a new pearl oyster Pinctada fucata martensii strain has begun to be cultured as seafood. In the present study, the seasonal variation (February and June) in biochemical composition and flavor compounds in two P. f. martensii strains (strain for pearl production was abbreviated to PP, and seafood was abbreviated to PE) were detected to compare the nutritional and flavor differences between them, and to provide a reference for the seasonal preference of consumers for eating P. f. martensii. The ratio of soft tissues in PE-Feb was significantly higher than that in PP-Feb (p < 0.05). The contents of ash, crude protein, and crude lipid were higher in PP than those in PE in the same season, while significantly higher contents of glycogen in the PE strain were observed compared to the PP strain in the same season (p < 0.05). The major amino acids (such as Glu and Asp) and PUFA (such as DHA and EPA) were almost the same in two P. f. martensii strains in the same season, while the contents of these nutrients were significantly higher in February compared to June (p < 0.05). Taurine content in PE-Feb was the highest (19.58 mg/g wet weight), followed by PP-Jun, PP-Feb, and PE-Jun. The umami and sweet FAA contents of the same P. f. martensii strain in February were significantly higher than those in June (p < 0.05). The AMP content in PP-Jun was the highest (64.17 mg/100 g wet weight), followed by PP-Feb, PE-Jun, and PE-Feb. Succinic acid was the major organic acid, and its content in February was significantly higher than in June (p < 0.05). The betaine content in PP-Feb was the highest (23.02 mg/g of wet weight), followed by PE-Feb (20.43 mg/g of wet weight), PP-Jun (16.28 mg/g of wet weight), and PE-Jun (12.33 mg/g of wet weight), and significant differences were observed among these four groups (p < 0.05). In conclusion, the edible P. f. martensii strain harvest in February is rich in protein, glycogen, PUFA (DHA and EPA), taurine, succinic acid, and betaine, which could provide healthy nutrition and a good flavor for humans. Full article

Microalgae serve as feedstock for bivalves and larvae in aquaculture. The production of microalgae in large quantities is, however, characterized by the high cost of major nutrients and vitamins and scarcity of freshwater. Wastewater is a cheap alternative medium for microalgae cultivation. The wastewater provides essential nutrients for microalgae growth and biomass production. This study examined the biomass productivity, nutrient removal, and biochemical content of Chlorella vulgaris, Spiruna platensis, and Haematococcus pluvialis biomass cultivated in membrane treated distillery wastewater (MTDW). The study further examined the use of cultivated biomass as a diet to analyze the growth and survival rate of Pinctada fucata martensii. The results showed 79.61% and 82.89%, and 41.73% of Total Nitrogen (TN) and 74.95%, 78.21%, and 29.05% of Total Phosphorus (TP) removal efficiency for C. vulgaris, S. platensis, and H. pluvialis respectively. Biomass productivity of 0.069 g L⁻¹, 0.086 g L⁻¹, and 0.057 g L⁻¹, 43.3%, 40.9%, and 34.9% (protein), 10.3%, 14.5%, and 13.8% (lipid), and 16.4%, 14.8%, and 20.8% (carbohydrate) for C. vulgaris, S. platensis, and H. pluvialis respectively. The specific growth rate and survival rate of pearl oysters were significantly (p < 0.05) higher (0.99 ± 0.12%, 87.3%) under C. vulgaris diet compared to S. platensis and H. pluvialis diets. Full article

Fibroblast growth factor 18 (FGF18) plays an important functional role in skeletal growth and development. The FGF18 gene was characterized in pearl oyster Pinctada fucata martensii (PmFGF18) with the full-length sequence containing an open reading frame of 714 bp encoding 237 amino acids. The domain analysis of PmFGF18 showed a distinctive FGF domain, with a high similarity to FGF18 protein sequences from Crassostrea gigas (43.35%) and C. virginica (37.43%). PmFGF18 expression was revealed in all analyzed tissues with a significantly higher expression level in the fast-growing group than the slow-growing group. The analysis of PmFGF18 polymorphism demonstrated 33 SNPs (single nucleotide polymorphisms) in the CDS and promoter region of PmFGF18 sequence. Association analysis revealed 19 SNPs (2 SNPs from CDS and 17 SNPs from the promoter region) associating significantly with growth traits. Among the associated SNPs, one SNP g.50918198 A > C was verified in the other breeding line. Therefore, PmFGF18 can be utilized as a candidate gene for growth, and its related SNPs could be used in selective breeding of P. f. martensii for the improvement of growth traits. Full article

Angiotensin-I-converting enzyme (ACE) inhibitory peptides derived from natural products have shown a blood pressure lowering effect with no side effects. In this study, two novel ACE inhibitory peptides (His-Leu-His-Thr, HLHT and Gly-Trp-Ala, GWA) were purified from pearl oyster (Pinctada fucata martensii) meat protein hydrolysate with alkaline protease by ultrafiltration, polyethylene glycol methyl ether modified immobilized metal ion affinity medium, and reverse-phase high performance liquid chromatography. Both peptides exhibited high ACE inhibitory activity with IC₅₀ values of 458.06 ± 3.24 μM and 109.25 ± 1.45 μM, respectively. Based on the results of a Lineweaver-Burk plot, HLHT and GWA were found to be non-competitive inhibitor and competitive inhibitor respectively, which were confirmed by molecular docking. Furthermore, the pearl oyster meat protein hydrolysate exhibited an effective antihypertensive effect on SD rats. These results conclude that pearl oyster meat protein is a potential resource of ACE inhibitory peptides and the purified peptides, HLHT and GWA, can be exploited as functional food ingredients against hypertension. Full article