Pearl Oyster Pinctada Maxima Research Articles

THE CHARACTERISTICS OF MARINE ENVIRONMENT AND SUITABILITY FOR PEARL OYSTER (Pinctada maxima) CULTIVATION IN BARRU REGENCY

The coastal waters utilization that has potential to be developed in Barru regency is the cultivation of pearl oysters (Pinctada maxima). However, to get the maximum results, site selection through inventory activities and mapping of potential of the waters is an important early stage to do. The purpose of this study was to assess the suitability of Barru regency coastal waters for pearl oysters (Pinctada maxima) farming. The method used in the current study were the characteristics analysis, plankton abundance SID analysis (Simpson's index of diversity), and suitability analysis of pearl oyster farming by weighting. Conditions of physical parameters i.e tidal waters was characterized by a mix tidal or semidiurnal tides which has two high tides and two low tides in each tidal day. The waters current ranged from 14 until 69 cm/s. Water depths contour ranged from 5 until >200 meters and the water temperature was relatively high at the first transitional season (May) which ranged from 30.1 to 31.6 0C. Chemical parameters, such as salinity, dissolved oxygen, pH, and nitrate still met the water quality standard of marine waters. However, the posphat concentration in the estuary had exceeded the level of quality standard , i.e >0.015 mg/L. Barru coastal waters that had the potential for pearl oysters (Pinctada maxima) farming with a very appropriate status has an area of 3,201 ha. Keywords: Coastal, Pearl oyster farming, Suitability, Environmental

THE CHARACTERISTICS OF MARINE ENVIRONMENT AND SUITABILITY FOR PEARL OYSTER (Pinctada maxima) CULTIVATION IN BARRU REGENCY

The coastal waters utilization that has potential to be developed in Barru regency is the cultivation of pearl oysters (Pinctada maxima). However, to get the maximum results, site selection through inventory activities and mapping of potential of the waters is an important early stage to do. The purpose of this study was to assess the suitability of Barru regency coastal waters for pearl oysters (Pinctada maxima) farming. The method used in the current study were the characteristics analysis, plankton abundance SID analysis (Simpson's index of diversity), and suitability analysis of pearl oyster farming by weighting. Conditions of physical parameters i.e tidal waters was characterized by a mix tidal or semidiurnal tides which has two high tides and two low tides in each tidal day. The waters current ranged from 14 until 69 cm/s. Water depths contour ranged from 5 until >200 meters and the water temperature was relatively high at the first transitional season (May) which ranged from 30.1 to 31.6 0C. Chemical parameters, such as salinity, dissolved oxygen, pH, and nitrate still met the water quality standard of marine waters. However, the posphat concentration in the estuary had exceeded the level of quality standard , i.e >0.015 mg/L. Barru coastal waters that had the potential for pearl oysters (Pinctada maxima) farming with a very appropriate status has an area of 3,201 ha.
 Keywords: Coastal, Pearl oyster farming, Suitability, Environmental

Non-invasive DNA collection for parentage analysis for bivalves: A case study from the silver-lipped pearl oyster (Pinctada maxima)

Due to the high revenues generated by the pearl industry, interest in developing breeding programs is increasing. The traditional approach for collecting DNA for pedigree analyses in breeding programs for the silver-lipped pearl oyster (Pinctada maxima) involves tissue excision from the muscular foot and/or mantle. Tissue excision causes injury and stress to the animal, and can lead to reduced growth efficiency, bacterial infection and subsequent mortality when oysters are returned to the non-sterile marine environment. The approach of swabbing tissue to collect cells for DNA analyses offers a potential non-invasive and rapid method but has not been reported previously for pearl oysters; particularly where DNA is destined for a high-throughput genotype-by-sequencing (GBS) single nucleotide polymorphism (SNP) genotyping platform. To evaluate the potential of swabbing as a method to collect DNA for downstream GBS SNP genotyping under commercial farming conditions, 29 broodstock pearl oysters were swabbed with two different swab brushes (a stiff and soft brush). Concentration of the extracted DNA from swabs was found to meet requirements for genotyping (44 to 59 ng/μL) and 260/280 ratios were in the acceptable range for DNA purity (1.9–2.2). SNP genotype calls derived from swab samples were highly correlated with those derived from tissue excised from the same oyster (mean of 0.97 ± 0.04 for soft bristle – mean of 0.98 ± 0.02 for stiff bristle). Finally, we evaluated the performance of swabbing under a commercial breeding program scenario, whereby 923 spat were genotyped and 18 months later 1927 pearl oysters from the same commercial cohort were swabbed to determine parental contributions for the cohort at the two time periods. Results demonstrated that the swab method is reliable for collecting sufficient quantity and quality of DNA for genome-wide SNP genotyping enabling accurate pedigree reconstruction. This study validated the efficiency of the use of the swab technique to collect DNA for routine parentage assignment, while limiting the adverse effects of destructive tissue sampling for commercial use and/or for the development of breeding programs.

Comparative Profiling of Survival, Growth, and Intestinal Microbial Community of Pearl Oyster Pinctada maxima Juvenile in the Industrial Farming: The Feasibility of Using Spray-Dried Microalgae Powder

Industrial farming is an alternative mode for Pinctada maxima juvenile cultivation to avoid mass mortality caused by natural disasters. Suitable and enough food is crucial for successful industrial bivalve farming. To investigate the feasibility of live microalga instead of spray-dried microalgal powder in P. maxima juvenile industrial farming, this study replaces a positive control live microalgal diet [Isochrysis zhanjiangensis (L-iso) and Platymonas subcordiformis (L-pla)] with spray-dried I. zhanjiangensis powder (P-iso) and P. subcordiformis powder (P-pla). Continuous feeding trials (30 days) were conducted on the P. maxima juvenile (1.2008 ± 0.0009 g initial weight and 30.12 ± 0.05 mm initial shell length), under laboratory conditions. Survival, growth performance, and intestinal microbial community were studied and compared across the groups. Results showed that survival rate (SR) did not differ significantly across the groups (ranged from 84 to 86%, P > 0.05). The growth performance in spray-dried microalgal groups, including total weight (TW), shell height (SH), absolute growth rate (AGR), and relative growth rate (RGR) for SH and TW, was slightly lower than that in live microalgal groups, while the activities of pepsin (PES), amylase (AMS), and lipase (LPS) were significantly higher (P < 0.05). The best growth performance was observed in the L-iso group, followed by the L-pla group. A 16S rRNA-based sequencing revealed that Proteobacteria was the dominant phylum in P. maxima juvenile intestinal bacterial community under controlled conditions, which accounted for 62–82% across groups. The intestinal bacteria at the genus level were more sensitive to diets, whereas Burkholderia was the dominant genus in both L-iso (66.52 ± 6.43%) and L-pla groups (54.00 ± 5.66%), while Mycoplasma, Alphaproteobacteria, and Oxyphotobacteria were in both P-iso and P-pla groups. The P-pla group got higher ACE, Chao1, and Simpson and Shannon indices (P < 0.05). The above results suggested that the spray-dried P-iso and P-pla can serve as substitutes for live microalga in P. maxima juvenile industrial farming under controlled conditions. The finding in this study provides basic data to optimize industrial farming technology and healthy management for P. maxima juvenile.

Cdna Cloning and Expression Analysis of Chaperonin Containing T-Complex Polypeptide 1-Alpha in the Pearl Oyster Pinctada maxima Exposed to Cold Stress

The complete cDNA sequence of chaperonin-containing T-complex polypeptide 1-alpha (CCT-alpha) gene of the pearl oyster Pinctada maxima was determined using rapid amplification of cDNA ends technique and characterized with bioinformatic analysis. Its expression profile in different organs and under cold stress was characterized using real-time quantitative polymerase chain reaction. Results revealed that the complete cDNA sequence of P. maxima CCT-alpha has 1,803 base pairs (bp), including a 1,608-bp open reading framework that codes 535 amino acids. The protein has three conservative functional domains: equatorial, apical, and intermediate domains. The equatorial domain is 20 amino acids shorter than that of other species, and contains the three signature sequences of CCT family protein. The CCT-alpha of P. maxima has nine conservative ATP-binding sites and six protein-binding sites, and has high homology with Aplysia californica (80.7%), Delia antiqua (77.4%), Danio rerio (77.1%), Xenopus laevis (76.7%), Gallus gallus (76.4%), and Homo sapiens (75.4%). The CCT-alpha shows tissue-specific expression profile in P. maxima, with expression levels higher in gill, mantle, and adductor muscle than in hepatopancreas and heart. Cold stress markedly increased mRNA contents of CCT-alpha in the organs of P. maxima, but different organs showed distinct cold stress response pattern. Chaperonin-containing T-complex polypeptide 1-alpha transcription in adductor muscle, hepatopancreas, and heart increased at 2 h, and reached peak values at 6 h, maintained high levels at 12 h, and significantly decreased at 24 h. The product in gill and mantle decreased at 2 h, began to increase at 6 h, and showed a large increase at 12 h, but reduced to below the initial level at 24 h.

Analysis of macro nutrient content in biofouling waste organic fertilizer pearl oyster (Pinctada maxima L.)

Biofouling development is a major problem in bilvave aquaculture around the world. The purpose of this study was to obtain macro nutrient analysis data for organic fertilizer from pearl oyster (Pinctada maxima L) biofouling waste. Where is the manufacture of solid organic fertilizer products that have quality equivalent to other commercial organic fertilizers by utilizing pearl oyster (Pinctada maxima L.) biofouling waste so that high quality solid organic fertilizers are produced which are in accordance with the Quality Standards for solid organic fertilizers and the Indonesian National Standard. Organic fertilizer from pearl oyster biofouling waste is obtained by using pearl oyster biofouling waste which is taken from the results of cleaning microorganisms attached to the pearl oyster shell area. Another major concern regarding biofouling is the potential for food competition caused by the attachment of the filter-feeder. Besides, the waste of biofouling pearl oysters is extracted and soaked in fresh water for one week at a time. Afterward, the pearl oyster biofouling waste is dried in the sun to dry, odorless, blackish brown in color. Analysis of macro nutrient content using Atomic Absorption Spectrophotometer and UV-Vis Spectrophotometer. The results of the analysis of macro nutrient content were Water Content (5.76%), C (14.48%), Organic Matter (24%), N-total (0.92%), P-total (0, 25%), K-total (1.02%), C/N ratio (15.72).

Pearl Oyster Bacterial Community Structure Is Governed by Location and Tissue-Type, but Vibrio Species Are Shared Among Oyster Tissues.

Diseases of bivalves of aquacultural importance, including the valuable Australian silver-lipped pearl oyster (Pinctada maxima), have been increasing in frequency and severity. The bivalve microbiome is linked to health and disease dynamics, particularly in oysters, with putative pathogens within the Vibrio genus commonly implicated in oyster diseases. Previous studies have been biased toward the Pacific oyster because of its global dominance in oyster aquaculture, while much less is known about the microbiome of P. maxima. We sought to address this knowledge gap by characterizing the P. maxima bacterial community, and we hypothesized that bacterial community composition, and specifically the occurrence of Vibrio, will vary according to the sampled microenvironment. We also predicted that the inside shell swab bacterial composition could represent a source of microbial spillover biofilm into the solid pearl oyster tissues, thus providing a useful predictive sampling environment. We found that there was significant heterogeneity in bacterial composition between different pearl oyster tissues, which is consistent with patterns reported in other bivalve species and supports the hypothesis that each tissue type represents a unique microenvironment for bacterial colonization. We suggest that, based on the strong effect of tissue-type on the pearl oyster bacterial community, future studies should apply caution when attempting to compare microbial patterns from different locations, and when searching for disease agents. The lack of association with water at each farm also supported the unique nature of the microbial communities in oyster tissues. In contrast to the whole bacterial community, there was no significant difference in the Vibrio community among tissue types nor location. These results suggest that Vibrio species are shared among different pearl oyster tissues. In particular, the similarity between the haemolymph, inside shell and solid tissues, suggests that the haemolymph and inside shell environment is a source of microbial spillover into the oyster tissues, and a potentially useful tool for non-destructive routine disease testing and early warning surveillance. These data provide important foundational information for future studies identifying the factors that drive microbial assembly in a valuable aquaculture species.

Molecular identification of bacteria isolated from culture medium of the gold-lipped pearl oyster Pinctada maxima larvae

Abstract. Wullur S, Napitupulu H, Wantania LL, Ginting EL, Mamangkey NGF, Smolak R, Ogello E. 2020. Molecular identification of bacteria isolated from culture medium of the gold-lipped pearl oyster Pinctada maxima larvae. Biodiversitas 21: 5291-5297. This study was conducted for the molecular identification of bacteria species isolated from culture medium of the gold-lipped pearl oyster, Pinctada maxima larvae. The pearl oysters were cultured using live-microalgae (Isochrysis sp) and fish waste diet (FWD) as food sources. Bacteria were isolated from the oyster larvae and identified based on the 16S rRNA gene sequence. The isolated bacteria were grown on agar plates and incubated at 37°C for 24 to 48 hours. Representative colonies of the bacteria were selected and cultured for molecular analysis. The 16S rRNA genes of the bacteria were amplified and the sequences were matched with the NCBI GenBank database. Seven different colonies were observed based on morphological characters. Similarity test by conducting the Basic Local Alignment Search Tool (BLAST) in the NCBI GenBank database, using the 16S rRNA gene sequences showed that the seven isolates colonies possess high similarity to five bacteria species i.e. Pseudomonas pachastrellae, Vibrio alginolyticus, Bacillus filamentosus, Bacillus cereus and Idiomarina fontislapidosi belonging to four different genera i.e. Bacillus, Staphylococcus, Vibrio, and Alteromonas.

Characterization and development of SSR markers of Pinctada maxima by RNA-Seq approach

In this study, we developed microsatellite markers, analyzed their distribution and frequency and verified polymorphism based on the transcriptome data of pearl oyster Pinctada maxima. Totally, 58,121 potential EST-SSRs from 145,877 sequences were identified. We randomly selected 100 of these primer pairs for further validation in the stock, 76 primer pairs were successfully amplified and 25 primer pairs were found to be polymorphic. The number of alleles at each locus ranged from 2 to 5, with an average allele number of 2.96. The observed heterozygosity ranged from 0.185 to 0.931 with an average of 0.656. The expected heterozygosity ranged from 0.337 to 0.754 with an average of 0.552. The polymorphic information content ranged from 0.263 to 0.690 with an average of 0.462. These markers will provide an effective tool for genetic diversity, genetic map construction and molecular-assisted breeding in the species of P. maxima.

XÁC ĐỊNH HỆ SỐ TÍCH TỤ HÓA CHẤT BẢO VỆ THỰC VẬT CƠ CLO (OCPs) TRONG MỘT SỐ LOÀI NHUYỄN THỂ HAI MẢNH VỎ Ở KHU VỰC CỬA SÔNG SOÀI RẠP - TpHCM

Deposited sediments contain organochlorine pesticide chemicals which can pollute surface water as well as aquatic ecosystems. In this study, the accumulation of organochlorine pesticide chemicals in the bivalve mollusk group including Pacific oyster (Crassostrea gigas, Thunberg, 1793), green mussel (Perna viridis), blood scallop (Anadara granosa) ), white clam (Meretrix lyrata) and pearl oyster (Pinctada maxima) at Soai Rap estuary, Ho Chi Minh city was selected as subject of this research because of their high bioaccumulation capacity; their sedentary life, organic residue filter feeding habit and the ability to clean the lagoon environment. The pesticide chemicals were analyzed on GC-ECD system. Result of this research shows the different levels of accumulation in meat tissues of 5 species but they are lower than the allowable value of MARD 193:2004 - The bivalve mollusk harvest zone - Conditions to ensure food hygiene and safety. The results of calculating the Bio-Accumulation Factor (BAF) and Biota Sediment Accumulation Factor (BSAF) of the five species have shown that the bioaccumulation of organochlorine pesticides (OCPs) of bivalve mollusks in the area is natural tendency. BAF and BSAF of Crassostrea gigas were 56.672 and 0.429, Perna viridis were 66.730 and 0.608, Anadara granosa were 123.884 and 1.974, Meretrix lyrata were 52.060 and 0.489, Pinctada maxima were 115.176 and 1.076, respectively.

Redescription of Larval Development in Cultured Pearl Oyster Pinctada maxima

Larval development plays a major role in efficient pearl culture. The cultured larvae will be later used for recipient and donor oysters in cultured pearl production. Larval developmental stage of silver lip pearl oyster Pinctada maxima has been reported by several studies. Those studies used female and male oyster parents directly taken from natural habitat.This study aimed to redescribe larval development of P. maxima from commercial pearl oyster culture farm in Indonesia. Larval development of this species whose parents are originated from selected groups in the pearl culture farm has not been reported yet, thus it is necessary to be described. This species undergoes specific larval developmental stage. The larvae were observed under microscope, and then the average shell length (SL) and shell height (SH) were measured. D-shaped veliger larva (77.4±0.3 µm SL; 65.4±1.1 µm SH) appeared 20 h after fertilization. Tenday-old larva (156.2±2.8 µm SL; 149.5±5.6 µm SH) had developed umbo region so it was called umbonal larva. Umbonal larva then developed further into plantigrade larva (411.3±9.8 µm SL; 380.5±6.9 µm SH) in 25 days after fertilization. Developmental stage and larval sizein P. maxima is similar with those observed in P. fucata and P. margaritifera. Keywords: growth, larva, plantigrade, shell, umbo, veliger

Studi of Environmental Optimum for Pearl Oyster (Pinctada maxima) Aquacuolture Using Marine GIS and Remote Sensing Case Study of Buleleng Regency, North Bali, Indonesia

Oyster aquaculture is one of priorities for development and promotion of aquaculture activities in Buleleng Regency and since 2010 the production always increase and supports coastal communities. The selection of aquaculture structure system and farm site are importance. The selection should be based on an appraisal of the life history, habits, environmental parameters and socio-infrastructure. This study focused on obtaining the aquaculture structure system and site selection for Pearl Oyster (Pinctada maxima) in Buleleng Regency with seven attributes Chl-a, SST, bathymetry, and currents, distance to town, distance to pier, and distance to laboratory. The model structure for identifying culture structure and suitable sites for oyster aquaculture in coastal of Buleleng Regency was built on MCE (Multi Criteria Evaluation), the final result for suitable site outputs were compared with pearl production in Buleleng Regency in 2009, 2010, and 2011. The result of this study is that most areas at Buleleng coastal had medium suitability scores.

Metabolomic responses of juvenile pearl oyster Pinctada maxima to different growth performances

Similar to other marine bivalves, Pinctada maxima shows unsynchronized growth, but the underlying metabolic mechanisms have not been studied. In this study, gold-lipped pearl oyster P. maxima from cultured stocks were selected to produce progeny stock. At 180 days, the stock was sorted by size, and fast-growing individuals and slow-growing individuals were separately sampled. Then, a metabolomic approach based on gas chromatography–mass spectroscopy was applied to assess the metabolite changes between the fast-growing and slow-growing groups of P. maxima and to understand the mechanism of their unsynchronized growth. In the metabolomics assay, among the 896 peaks isolated, 111 metabolites were revealed a spectral similarity value of >700 by using mass spectrum matching, and 48 were considered as significantly different metabolites (SDMs; VIP > 1 and P < 0.1) between the fast-growing and slow-growing groups. Results revealed that pearl oyster P. maxima changes metabolic status with different growth performance. Pathway analysis indicated that these SDMs were involved in 11 pathways. Further integrated key metabolic pathway analysis showed that pearl oysters possessed different capabilities in valine, leucine, and isoleucine biosynthesis, glycine, serine, and threonine metabolism, pyrimidine metabolism, cysteine and methionine metabolism, and glutathione metabolism between fast-growing and slow-growing groups. This study is the first metabolomics study to identify the key pathways and crucial metabolites so as to understand the metabolic mechanism of unsynchronized growth of bivalves.

KOMPOSISI JENIS BIOFOULING PADA TIRAM MUTIARA (PINCTADA MAXIMA) DI LAHAN BUDIDAYA PT. AUTORE PEARL CULTURE LOMBOK

Cultivation of pearl oyster Pinctada maxima types are increasingly in demand in Indonesia. This oyster living and concentrated on waters that have coral reefs and sandy rubble. Oyster cultivation is very promising given pearls produced have a high economic value. Eventhough, pearl oyster farming efforts not always performing well because there is a possibility of oysters will get the disease and even death. One reason is their biofouling attached to the basket or on the oyster shell is maintained. The existence and amount of biofouling usually varies depending on the time and conditions of the waters where the cultivation have been. This study aims to determine the types of biofouling were found at three different sites located on land cultivation PT. Pearl Culture Autrore Lombok. Study sample is limited to biofouling found on new and used baskets and pearl oyster shells P. maxima. The main parameters measured were the species composition and abundance, while the supporters of the parameters measured were temperature, salinity, current speed, the brightness of the waters and TSS (Total Suspended Solid). The results found 36 types of biofouling, including 21 types of animal groups with six phyla (arthropods, bryozoans, annelids, cnidarians, sponges and molluscs), and 15 species of the plant with two divisio (Spermatophyta and Thallophyta). In addition, it was found that water conditions have an influence on the biomass and the number of types of biofouling and the distance between substations in each station does not have a significant influence on biomass and the number of types of biofouling.Keywords: Biofouling, Pearl Oyster (Pinctada maxima ), PT. Autore Pearl Culture Lombok

Transcriptome analysis of the immune reaction of the pearl oyster Pinctada fucata to xenograft from Pinctada maxima

The pearl oyster Pinctada maxima exhibits great difficulty to culture pearls through nuclear insertion with an allograft, but it is easy for P. fucata to culture pearls after allografting. If P. fucata could be used as a surrogate mother to culture P. maxima pearls, it would benefit the pearl culture industry of P. maxima. However, this is blocked by the immune rejection of P. fucata against P. maxima mantle grafts. In this study, the immune responses of P. fucata hemocyte to allograft and xenograft were investigated after transplantation by transcriptome analysis. In total, 107.93 Gb clean reads were produced and assembled using the reference genome of P. fucata. Gene Ontology Term enrichment and KEGG enrichment analyses indicated that apoptosis, hippo signaling pathway, oxidation-reduction, MAPK signaling pathway, ribosome, protein processing in endoplasmic reticulum, purine metabolism, NF-kappa B signaling pathway, oxidative phosphorylation, Ras signaling pathway, and ubiquitin mediated proteolysis were involved in response to transplantation. Many genes related to oxidation-reduction reactions, the MAPK signaling pathway, and apoptosis were identified by comparison of the allograft group and the xenograft group at 0 h, 6 h, 12 h, 24 h, 48 h, 72 h, and 96 h post-transplantation. Among them, the expression levels of NADH dehydrogenase, succinate dehydrogenase and other dehydrogenases were increased significantly in the xenograft groups compared with allograft groups at 0 h post transplantation, indicating that a respiratory burst of neutrophils occurred immediately after xenograft transplantation. Additionally, HSP70 was highly expressed from 0 h to 96 h in the xenograft groups, indicating an oyster immune response to the xenograft. The genes enriched in the ribosome and hippo-signaling pathways were also identified, and expression patterns of these DEGs were different as compared between transplantation and control groups. Finally, altered expression levels of 10 randomly selected immune-related DEGs were confirmed by quantitative real-time PCR. These results indicated that oxidation-reduction is likely the key factor responsible for immune rejection to transplantation. The findings should provide some new insight into the molecular mechanism of immune rejection of the host against xenograft, and thus benefit to development of immunosuppressive reagents to facilitate effective xenograft pearling.

Effects of different substrates on settlement and growth of pearl oyster (Pinctada maxima) larvae in hatcheries

Metamorphosis of pearl oyster Pinctada maxima pediveliger is affected by physical and chemical characteristics of the collectors. In the present study, we conducted four experiments to evaluate the effects of collector characteristics on the settlement and growth of hatchery-reared pearl oyster. In the first experiment, black, red, yellow, and white plastic sheets were used as collectors. Settlement of P. maxima larvae in black and red plastic sheets was significantly higher than that in yellow and white plastic sheets (P<0.05). Mean shell length was not significantly different among the four colored sheets (P>0.05). In the second experiment, pediveliger larvae were settled onto palm rope and polypropylene rope collectors. The number of spat in the palm rope collector was significantly higher than that of spat in the polypropylene rope collector (P<0.05). Mean shell length was not significantly different between palm rope and polypropylene rope collectors (P>0.05). In the third experiment, settlement and subsequent growth were compared between plastic sheets with and without biofilm. The number of spat in the plastic sheets with biofilm was significantly higher than that in the plastic sheets without biofilm (P<0.05). Mean shell length after settlement were not significantly affected (P>0.05). In the fourth experiment, pediveliger larvae were stored in tanks with (experimental group) and without collectors (control group). The settlement rate of larvae on the wall was not significantly different between the two groups(P>0.05). The settlement rates of the larvae on the wall and collectors in the experimental group were significantly larger than those on the wall in the control group(P<0.05). Mean shell length was not significantly different between the groups (P>0.05). Our results suggest that appropriate selection of collector types, color, and conditioning can improve the settlement of P. maxima larvae in hatcheries.

Protease enzyme reactability effect of pearl oyster (Pinctada maxima) flesh shell growth at different water temperature and salinity

Protease enzyme reactability effect of pearl oyster (Pinctada maxima) flesh shell growth at different water temperature and salinity

Growth pattern and biometric relationship of pearl oyster Pinctada maxima cultured in Beibu Bay, China

ABSTRACTA progeny stock was established by using gold-lip breeders collected from Indonesia to understand the growth characteristics of pearl oyster Pinctada maxima in Beibu Bay, China. The shell height and shell length of the stock were measured from April 2011 to September 2013. Water parameters, such as water temperature, salinity, dissolved oxygen concentration, and suspended organic matter, were monitored during the experimental process. Results showed seasonal trends in water temperature and suspended organic matter. Shell height and shell length were significantly related at different ages (P < .05). The estimated von Bertalanffy growth parameters were SH∞ = 178.75 mm and K = 0.41 per year for shell height, and SL∞ = 152.74 mm and K = 0.50 per year for shell length. The growth performance indexes for shell height and shell length were 4.02 and 4.07, respectively. This study provides valuable information for the optimization of the production management of pearl oyster P. maxima in the area.

Unravelling the effects of gene flow and selection in highly connected populations of the silver-lip pearl oyster (Pinctada maxima)

Many marine organisms often display weak levels of population genetic structuring as a result of both environmental characteristics (e.g., ocean currents) and life history traits (e.g., widely dispersed planktonic larval stages) maintaining high levels of gene flow. This can lead to the assumption that these organisms can be managed as a single stock based on high levels of population connectivity. However, this neglects to account for other micro-evolutionary forces such as selection, which also shape these populations. This study utilizes 1130 genome-wide SNP loci to unravel the effects of gene flow and selection shaping three highly connected populations of the silver-lip pearl oyster (Pinctada maxima) in the ecologically and economically important Indo-Pacific region (Aru, Bali, and West Papua). Twenty-two loci under directional selection were identified amongst the populations, providing further supporting evidence of strong local adaptation (i.e., G×E effects) among populations in this region. Global Fst values for directional outliers (0.348) were up to eight times greater than for neutral markers (0.043). Pairwise Fst comparisons between Aru and Bali revealed the largest directional differences (0.488), while Bali and West Papua had the least (0.062). Unrooted neighbour-joining (NJ) distance trees and genetic diversity indices of directional outliers revealed that individuals from Bali and West Papua had reduced allelic variation (MAFavg=0.144, Ho=0.238 and MAFavg=0.232, Ho=0.369, respectively) compared to Aru (MAFavg=0.292, Ho=0.412). This indicates that directional selection is most likely acting upon genetic variation within the Bali and West Papua populations. NJ distance trees, discriminant analysis of principal components, and Fst analyses of directional outliers revealed two divergent groups (“Bali/West Papua”; “Aru”) that had previously gone unrecognized. This study not only illustrates that relatively strong local adaptive forces are occurring despite high gene flow, but identifies the populations that are most likely experiencing selection. Additionally, this study highlights the need to understand all micro-evolutionary forces acting on populations when resolving stock structure.

Temporal Tracking of Mineralization and Transcriptional Events Associated with Shell Formation During the Early Life History of Pearl Oyster Pinctada maxima

Background: Molluscan larval ontogeny is a highly conserved process comprising three principal developmental stages; trochophore, veliger and metamorphosis into the juvenile. A characteristic that is unique to each of these stages is shell design, termed prodissoconch I, prodissoconch II and dissoconch in bivalves. These shells vary in morphology, mineralogy and microstructure. The discrete temporal transitions in shell biomineralization between these larval stages are utilized in this study to investigate transcriptional involvement in several distinct biomineralization events. Methods: Scanning electron microscopy, X-ray diffraction and microarray differential gene expression analysis were used to document temporal transitions in morphology, mineralogy and microstructure of larval shells and the genes directing their biomineralization. Results: P. maxima larvae and juveniles collected throughout post-embryonic ontogenesis are described in terms of mineralogy and microstructure of each shelled stage as well as establishing a timeline for transitions in biomineralization. P. maxima larval samples most representative of these biomineralization distinctions and transitions were analyzed for differential gene expression with the microarray platform PmaxArray 1.0. A number of known shell matrix genes and novel transcripts are reported as differentially expressed in correlation to the mineralization events of P. maxima larval ontogeny. However, only a single transcript, PM066, was noted as being expressed before and after the transition to the adult shell design. No other known/putative adult shell matrix genes from P. maxima were detected in association with the larval shells prodissococh I and II, suggesting that their expression is either below detection limits or an almost entirely different set of genes is potentially responsible for larval and adult shell mineralization. Conclusion: This interdisciplinary investigation has linked the shell developments of P. maxima larval ontogeny with corresponding gene expression profiles, furthering the elucidation of bivalve development and shell biomineralization. Keywords: Biomineralization, gene expression, microarray, mollusc, ontogeny, pearl oyster.