The Experts below are selected from a list of 309 Experts worldwide ranked by ideXlab platform
Paul C Southgate - One of the best experts on this subject based on the ideXlab platform.
-
economic feasibility of small scale mabe pearl production in tonga using the winged pearl oyster pteria penguin
Aquaculture Reports, 2020Co-Authors: William Johnston, Sophie E Gordon, Tuikolongahau Halafihi, Damian Hine, Max Wingfield, Paul C SouthgateAbstract:Abstract Mabe pearl culture is an increasingly important rural livelihood in south Pacific countries as it offers a low-cost, low-tech alternative to round pearl culture. Mabe pearl production can be achieved by local people with appropriate training, and the products offer further livelihood opportunities through value-adding and local production of jewellery and handicraft items. The Kingdom of Tonga is unique among south Pacific pearl producing countries in focusing primarily on mabe pearl, not round pearl, culture using the winged pearl oyster, Pteria penguin. The Tongan mabe pearl sector has developed rapidly over recent years and is sustained by routine hatchery production of spat and recently improved pearl culture methods. This study determined establishment and operational costs of a subsistence-level mabe pearl farm in Tonga and developed an economic model to assess potential profitability of such operations. The representative mabe pearl farm modelled in this study targeted annual mabe pearl production from 100 oysters. Estimated capital cost (US dollars; USD) was USD 2,027 and major production costs were labour (29%), marketing (24%), and capital purchase and replacement (16%). Annual production of 231 saleable mabe pearls generated a net present value (NPV) of USD 107,101. The modified internal rate of return (MIRR) and benefit-cost ratio of the modelled mabe pearl farm were 20.46% and 4.86, respectively, with a payback period of 4 years. Given the average annual income in Tonga is USD 4,020, the modelled mabe pearl farm offers significant economic opportunity (USD 9,338 annual profit after all costs, including owner/operator wages) and supports additional socio-economic benefits for rural communities involved in downstream activities relating to handicraft and jewellery production, and tourism. The findings of this study assist stakeholder understanding of costs, risks and production levels required for profitable mabe pearl production.
-
Economic assessment of community-based pearl oyster spat collection and mabé pearl production in the western Pacific
Aquaculture, 2020Co-Authors: Bill Johnston, Pranesh Kishore, Damian Hine, Gary Bingnald Vuibeqa, Paul C SouthgateAbstract:Abstract Cultured pearl production, and associated activities, are of crucial social and economic importance to remote coastal communities in Polynesia and the western Pacific. This study determined the potential profitability of (1) community-based pearl oyster spat collection operations targeting Pinctada margaritifera, and the subsequent sale of pearl oysters to round pearl farms; and (2) the use of Pteria penguin, collected incidentally from P. margaritifera spat collection operations, for mabe pearl production. The spat collection farm modelled in this study comprised four 100-m longlines supporting 1240 commercial spat collectors, with an estimated capital cost of $1245 (all figures in USD). The spat collection operation produced 2332 saleable P. margaritifera pearl oysters (sold to round pearl culture operations) with estimated NPV of $10,439. The MIRR generated was 12.24%, with a benefit-cost ratio was 1.52, and a payback period of 4 years. The downstream mabe pearl farm modelled in this study comprised two 100-m longlines supporting 2000 implanted Pt. penguin oysters with an estimated capital cost of $7319. Annual production of 5400 mabe pearls generated an NPV of $491,864. The MIRR and benefit-cost ratio of the modelled mabe pearl farm were 22.64% and 7.24, respectively, with a payback period of 3 years. Incorporating production and price risk into the model reduced the expected NPV of the mabe pearl farm to $297,507. The models developed in this study provide valuable new information for prospective pearl oyster spat and mabe pearl farming community groups, donors, funding bodies and other stakeholders, and provide a valuable extension tool supporting further development of the pearl sector in Fiji and the broader Indo-Pacific region.
-
cost benefit analysis of two culture methods that influence pearl production from the black lip pearl oyster pinctada margaritifera
Journal of The World Aquaculture Society, 2019Co-Authors: Bill Johnston, Pranesh Kishore, Damian Hine, Paul C SouthgateAbstract:The black-lip pearl oyster, Pinctada margaritifera, used for round pearl production in Polynesia, is generally cultured using “ear-hanging” where they are attached to a rope to form “chaplets.” In other countries, pearl oysters are cultured using panel (pocket) nets that are more expensive than chaplets but afford more protection to cultured oysters. Prior research has shown panel nets produce pearls of higher quality and value, potentially generating higher profits. This study used cost–benefit analysis to compare pearl production using chaplet-based and panel net-based culture methods. Whole farm data, including gross revenues and annual production costs, fixed and variable, were analyzed. Average production cost per pearl using panel net-based culture was USD 22.47 and for chaplet-based culture was USD 21.55. However, use of panel nets saved around 3,430 hr (USD 6,860) of labor a year, offsetting the greater capital investment. A chaplet-based pearl farm generated USD 65,738 in annual profits compared to USD 88,774 for a panel net-based farm. Positive cash flow was achieved 1 year earlier (Year 7) for the panel net-based farm. This is the first economic analysis of different pearl culture methods for P. margaritifera and evidence of profitability will support further development of the black-lip pearl industry in the Indo-Pacific region.
-
effects of nucleus position profile and arrangement on the quality of mabe pearls produced by the winged pearl oyster pteria penguin
Aquaculture, 2019Co-Authors: Sophie E Gordon, Siolaa Malimali, Ipek D Kurtboke, Max Wingfield, Paul C SouthgateAbstract:The position and arrangement of nuclei is the most important technical aspect of mabe pearl (half-pearl) production. This study examined the effects of nucleus arrangement, profile (height) and position, on quality, nacre thickness and shape of mabe pearls produced by Pteria penguin. Oysters implanted with three nuclei produced a greater proportion of saleable mabe pearls with more regular shapes than oysters implanted with five nuclei. Use of low profile nuclei resulted in mabe pearls with increased nacre thickness and produced mabe pearls of significantly higher quality, with more regular shapes than high profile nuclei. Nucleus position significantly influenced mabe pearl quality, nacre thickness and shape. The posterior-ventral position of the left shell valve produced mabe pearls of the highest quality with the thickest nacre and was the best location for mabe pearl culture. Based on the results of this study, it is recommended that P. penguin is implanted with a maximum of three nuclei to increase the production of regular-shaped mabe pearls, and that low profile nuclei are used to improve quality and nacre thickness of mabe pearls produced in less favourable nucleus positions. An optimal nucleus arrangement for P. penguin of 130–150mm dorso-ventral height would include one high profile nucleus in the posterior-ventral position of the left shell plus additional low profile nuclei in both the anterior-ventral position of the left shell valve and, the center of the right shell. Based on the quality grading system used in this study, a minimum commercial nacre thickness of 0.25mm is recommended for mabe pearl production using P. penguin.
-
Using microradiography to assess nacre thickness of mabé pearls: Technique suitability and insights
Aquaculture, 2018Co-Authors: Sophie E Gordon, Pranesh Kishore, Siolaa Malimali, 'ana 'akau'ola, Max Wingfield, Paul C SouthgateAbstract:Abstract Nacre thickness is a major factor influencing the quality and value of half-pearls (‘mabe’), yet accurate determination of nacre thickness, in a non-destructive manner, is problematic. Microradiography is commonly used to measure the nacre thickness of round pearls, however the suitability of this technique for mabe has not previously been assessed. Mabe were cultured in winged pearl oysters (Pteria penguin) for periods of 200 to 380 days to produce pearls with a range of nacre thicknesses. The nacre thickness of each pearl was quantified using microradiography and standard micrometer techniques. A strong, significant relationship was observed between measurements obtained using both techniques (R2 = 0.88, P ≤ 0.001). Microradiography produced defined, measureable images, with a resolution of ±0.04 mm, for mabe pearls with nacre thicknesses between 0.1 and 1.3 mm. Mabe nacre thickness and pearl quality were significantly influenced by the position of the pearl nucleus within the shell (T(95) = 7.14, P
Kaoru Maeyama - One of the best experts on this subject based on the ideXlab platform.
-
Trivalent Iron Is Responsible for the Yellow Color Development in the Nacre of Akoya Pearl Oyster Shells
Marine Biotechnology, 2020Co-Authors: Makoto Kakinuma, Michio Suzuki, Shigeharu Kinoshita, Fumihiro Hattori, Ko Yasumoto, Chiaki Kasugai, Mirai Koide, Kayo Mitani, Kaho Shidoji, Kaoru MaeyamaAbstract:The gold and cream colors of cultured Akoya pearls, as well as natural yellow nacre of pearl oyster shells, are thought to arise from intrinsic yellow pigments. While the isolation of the yellow pigments has been attempted using a large amount of gold pearls, the substance concerned is still unknown. We report here on the purification and characterization of yellow pigments from the nacre of Akoya pearl oyster shells. Two yellow components, YC1 and YC2, were isolated from the HCl-methanol (HCl-MeOH) extract from nacreous organic matrices obtained by decalcification of the shells with ethylenediaminetetraacetic acid (EDTA). Energy-dispersive X-ray and infrared spectroscopy analyses suggested that YC1 and YC2 precipitated under basic conditions are composed of Fe-containing inorganic and polyamide-containing organic compounds, respectively. YC1 solubilized under acidic conditions exhibited positive reactions to KSCN and K_4[Fe(CN)_6] reagents, showing the same ultraviolet-visible absorption spectrum as those of Fe(III)-containing compounds. In addition, X-ray absorption fine structure analysis supported the compound in the form of Fe(III). The total amount of Fe was approximately 2.6 times higher in the yellow than white nacre, and most Fe was fractionated into the EDTA-decalcifying and HCl-MeOH extracts. These results suggest that Fe(III) coordinated to EDTA-soluble and insoluble matrix compounds are mainly associated with yellow color development not only in the Akoya pearl oyster shells but also in the cultured Akoya pearls.
-
gene expression profiles at different stages for formation of pearl sac and pearl in the pearl oyster pinctada fucata
BMC Genomics, 2019Co-Authors: Saori Take, Kaoru Maeyama, Kiyohito Nagai, Shugo Watabe, Shuichi Asakawa, Yoji Igarashi, Kazutoshi Yoshitake, Shigeharu KinoshitaAbstract:The most critical step in the pearl formation during aquaculture is issued to the proliferation and differentiation of outer epithelial cells of mantle graft into pearl sac. This pearl sac secretes various matrix proteins to produce pearls by a complex physiological process which has not been well-understood yet. Here, we aimed to unravel the genes involved in the development of pearl sac and pearl, and the sequential expression patterns of different shell matrix proteins secreted from the pearl sac during pearl formation by pearl oyster Pinctada fucata using high-throughput transcriptome profiling. Principal component analysis (PCA) showed clearly different gene expression profiles between earlier (before 1 week) and later stages (1 week to 3 months) of grafting. Immune-related genes were highly expressed between 0 h – 24 h (donor dependent) and 48 h – 1 w (host dependent), and in the course of wound healing process pearl sac was developed by two weeks of graft transplantation. Moreover, for the first time, we identified some stem cell marker genes including ABCG2, SOX2, MEF2A, HES1, MET, NRP1, ESR1, STAT6, PAX2, FZD1 and PROM1 that were expressed differentially during the formation of pearl sac. The expression profiling of 192 biomineralization-related genes demonstrated that most of the shell matrix proteins (SMPs) involved in prismatic layer formation were first up-regulated and then gradually down-regulated indicating their involvement in the development of pearl sac and the onset of pearl mineralization. Most of the nacreous layer forming SMPs were up-regulated at 2 weeks after the maturation of pearl sac. Nacrein, MSI7 and shematrin involved in both layer formation were highly expressed during 0 h – 24 h, down-regulated up to 1 week and then up-regulated again after accomplishment of pearl sac formation. Using an RNA-seq approach we unraveled the expression pattern of the key genes involved in the development of pearl sac and pearl as a result of host immune response after grafting. These findings provide valuable information in understanding the molecular mechanism of pearl formation and immune response in P. fucata.
-
Comparison of Two Pearl Sacs Formed in the Same Recipient Oyster with Different Genetic Background Involved in Yellow Pigmentation in Pinctada fucata
Marine Biotechnology, 2018Co-Authors: Mikihiro Shinohara, Shigeharu Kinoshita, Enkong Tang, Daisuke Funabara, Makoto Kakinuma, Kaoru Maeyama, Kiyohito Nagai, Masahiko Awaji, Shugo Watabe, Shuichi AsakawaAbstract:Color is one of the most important factors determining the commercial value of pearls. Pinctada fucata is a well-known pearl oyster producing high-quality Akoya pearls. Phenotypic variation in amount of yellow pigmentation produces white and yellowish pearls. It has been reported that polymorphism of yellow pigmentation of Akoya pearls is genetically regulated, but the responsible gene(s) has remained unknown. Here, we prepared pearl sac pairs formed in the same recipient oyster but coming from donor oysters that differ in their color. These two pearl sacs produced pearls with different yellowness even in the same recipient oyster. Yellow tone of produced pearls was consistent with shell nacre color of donor oysters from which mantle grafts were prepared, indicating that donor oysters strongly contribute to the yellow coloration of Akoya pearls. We also conducted comparative RNA-seq analysis and retrieved several candidate genes involved in the pearl coloration. Whole gene expression patterns of pair sacs were not grouped by pearl color they produced, but grouped by recipient oysters in which they were grown, suggesting that the number of genes involved in the yellow coloration is quite small, and that recipient oyster affects gene expression of the majority of genes in the pearl sac.
-
pearl production by implantation of outer epithelial cells isolated from the mantle of pinctada fucata and the effects of blending of epithelial cells with different genetic backgrounds on pearl quality
2018Co-Authors: Masahiko Awaji, Shigeharu Kinoshita, Makoto Kakinuma, Kaoru Maeyama, Kiyohito Nagai, Takashi Yamamoto, Yasunori Iwahashi, Fumihiro Hattori, Shugo WatabeAbstract:In the current method of pearl production, the mantle fragment of a donor pearl oyster is transplanted into a host pearl oyster together with an inorganic bead (pearl nucleus). After this surgical procedure, only outer epithelial cells (OEC) in the transplanted mantle survive in a host pearl oyster and form a pearl sac to begin pearl formation. Therefore, implantation of only the OEC instead of the mantle fragment would be a possible alternative to the current procedure. To examine the potential of pearl production by implanting OEC in Pinctada fucata, we developed a cell implantation method using the pearl nucleus carrying a small pit inoculated with OEC. As a result, approximately 70% of the inserted nuclei formed the nacreous layer when the OEC were inoculated at 5 × 104 cells/nucleus. Then, OEC isolated from two genetically different types of pearl oysters that significantly differed in shell nacre color (yellowness) were mixed at four different ratios, and the prepared OEC mixtures were transplanted to investigate the effects of the blend on the yellowness of pearls to be harvested. The yellowness of harvested pearls differed significantly in accordance with the mixing ratio. Similarly, OEC isolated from two types of pearl oysters that showed a significant difference in the thickness of their shell nacre aragonite tablets were mixed at four different ratios and transplanted. Mean thickness of the aragonite tablets of the harvested pearls differed according to mixing ratio. These results suggest the method to control pearl quality by blending OEC obtained from pearl oysters genetically improved by selective breeding for traits related to pearl quality.
-
gene expression patterns in the mantle and pearl sac tissues of the pearl oyster pinctada fucata
2018Co-Authors: Shigeharu Kinoshita, Kaoru Maeyama, Kiyohito Nagai, Shuichi Asakawa, Shugo WatabeAbstract:The shell of pearl oysters consists of two distinct layers, nacre and prismatic. Mantle is the tissue involved in the shell formation, and its ventral part (mantle edge) forms the prismatic layers, whereas the dorsal part (pallium) forms the nacre. In pearl culture, mantle grafts from the pallium of donor are transplanted into the recipient. Then pearl sac is formed by proliferation of epithelial cells from the grafted mantle to form pearls. It has been reported that gene expression patterns are different between mantle edge and pallium in accordance with their distinct functions in the shell formation. However, it is not well addressed whether gene expression is identical or not between two nacre-forming tissues, pallium and pearl sac. Here, we examined expression patterns of known genes related to nacre and prismatic layer formation in mantle edge, pallium, and pearl sac of Pinctada fucata. Although the pallium and pearl sac have the same function in terms of nacre formation, various genes were not expressed identically to the respective tissues, suggesting that shell matrix proteins differently function in the formation of shell nacre and pearls.
Kyall R. Zenger - One of the best experts on this subject based on the ideXlab platform.
-
Using Image Processing to Automatically Measure Pearl Oyster Size for Selective Breeding
2019 Digital Image Computing: Techniques and Applications (DICTA), 2019Co-Authors: Adrian Lapico, Mangalam Sankupellay, Louis Cianciullo, Trina Myers, Dmitry A. Konovalov, Dean R. Jerry, Preston Toole, David B. Jones, Kyall R. ZengerAbstract:The growth rate is a genetic trait that is often recorded in pearl oyster farming for use in selective breeding programs. By tracking the growth rate of a pearl oyster, farmers can make better decisions on which oysters to breed or manage in order to produce healthier offspring and higher quality pearls. However, the current practice of measurement by hand results in measurement inaccuracies, slow processing, and unnecessary employee costs. To rectify this, we propose automating the workflow via computer vision techniques, which can be used to capture images of pearl oysters and process the images to obtain the absolute measurements of each oyster. Specifically, we utilise and compare a set of edge detection algorithms to produce an image-processing algorithm that automatically segments an image containing multiple oysters and returns the height and width of the oyster shell. Our final algorithm was tested on images containing 2523 oysters (Pinctada maxima) captured on farming boats in Indonesia. This algorithm achieved reliability (of identifying at least one required oyster measurement correctly) equal to 92.1%.
-
Genome-Wide SNP Validation and Mantle Tissue Transcriptome Analysis in the Silver-Lipped Pearl Oyster, Pinctada maxima
Marine Biotechnology, 2013Co-Authors: David B. Jones, Dmitry A. Konovalov, Dean R. Jerry, Sylvain Forêt, Kyall R. ZengerAbstract:Pearl oysters are not only farmed for their gemstone quality pearls worldwide, but they are also becoming important model organisms for investigating genetic mechanisms of biomineralisation. Despite their economic and scientific significance, limited genomic resources are available for this important group of bivalves, hampering investigations into identifying genes that regulate important pearl quality traits and unique biological characteristics (i.e. biomineralisation). The silver-lipped pearl oyster, Pinctada maxima , is one species where there is interest in understanding genes that regulate commercially important pearl traits, but presently, there is a dearth of genomic information. The objective of this study was to develop and validate a large number of type I genome-wide single nucleotide polymorphisms (SNPs) for P. maxima suitable for high-throughput genotyping. In addition, sequence annotations and Gene Ontology terms were assigned to a large mantle tissue 454 expressed sequence tag assembly (96,794 contigs) and information on known bivalve biomineralisation genes was incorporated into SNP discovery. The SNP discovery effort resulted in the de novo identification of 172,625 SNPs, of which 9,108 were identified as high value [minor allele frequency (MAF) ≥ 0.15, read depth ≥ 8]. Validation of 2,782 of these SNPs using Illumina iSelect Infinium genotyping technology returned some of the highest assay conversion (86.6 %) and validation (59.9 %; mean MAF 0.28) rates observed in aquaculture species to date. Genomic resources presented here will be pivotal to future research investigating the biological mechanisms behind biomineralisation and will form a strong foundation for genetic selective breeding programs in the P. maxima pearling industry.
Shigeharu Kinoshita - One of the best experts on this subject based on the ideXlab platform.
-
Trivalent Iron Is Responsible for the Yellow Color Development in the Nacre of Akoya Pearl Oyster Shells
Marine Biotechnology, 2020Co-Authors: Makoto Kakinuma, Michio Suzuki, Shigeharu Kinoshita, Fumihiro Hattori, Ko Yasumoto, Chiaki Kasugai, Mirai Koide, Kayo Mitani, Kaho Shidoji, Kaoru MaeyamaAbstract:The gold and cream colors of cultured Akoya pearls, as well as natural yellow nacre of pearl oyster shells, are thought to arise from intrinsic yellow pigments. While the isolation of the yellow pigments has been attempted using a large amount of gold pearls, the substance concerned is still unknown. We report here on the purification and characterization of yellow pigments from the nacre of Akoya pearl oyster shells. Two yellow components, YC1 and YC2, were isolated from the HCl-methanol (HCl-MeOH) extract from nacreous organic matrices obtained by decalcification of the shells with ethylenediaminetetraacetic acid (EDTA). Energy-dispersive X-ray and infrared spectroscopy analyses suggested that YC1 and YC2 precipitated under basic conditions are composed of Fe-containing inorganic and polyamide-containing organic compounds, respectively. YC1 solubilized under acidic conditions exhibited positive reactions to KSCN and K_4[Fe(CN)_6] reagents, showing the same ultraviolet-visible absorption spectrum as those of Fe(III)-containing compounds. In addition, X-ray absorption fine structure analysis supported the compound in the form of Fe(III). The total amount of Fe was approximately 2.6 times higher in the yellow than white nacre, and most Fe was fractionated into the EDTA-decalcifying and HCl-MeOH extracts. These results suggest that Fe(III) coordinated to EDTA-soluble and insoluble matrix compounds are mainly associated with yellow color development not only in the Akoya pearl oyster shells but also in the cultured Akoya pearls.
-
gene expression profiles at different stages for formation of pearl sac and pearl in the pearl oyster pinctada fucata
BMC Genomics, 2019Co-Authors: Saori Take, Kaoru Maeyama, Kiyohito Nagai, Shugo Watabe, Shuichi Asakawa, Yoji Igarashi, Kazutoshi Yoshitake, Shigeharu KinoshitaAbstract:The most critical step in the pearl formation during aquaculture is issued to the proliferation and differentiation of outer epithelial cells of mantle graft into pearl sac. This pearl sac secretes various matrix proteins to produce pearls by a complex physiological process which has not been well-understood yet. Here, we aimed to unravel the genes involved in the development of pearl sac and pearl, and the sequential expression patterns of different shell matrix proteins secreted from the pearl sac during pearl formation by pearl oyster Pinctada fucata using high-throughput transcriptome profiling. Principal component analysis (PCA) showed clearly different gene expression profiles between earlier (before 1 week) and later stages (1 week to 3 months) of grafting. Immune-related genes were highly expressed between 0 h – 24 h (donor dependent) and 48 h – 1 w (host dependent), and in the course of wound healing process pearl sac was developed by two weeks of graft transplantation. Moreover, for the first time, we identified some stem cell marker genes including ABCG2, SOX2, MEF2A, HES1, MET, NRP1, ESR1, STAT6, PAX2, FZD1 and PROM1 that were expressed differentially during the formation of pearl sac. The expression profiling of 192 biomineralization-related genes demonstrated that most of the shell matrix proteins (SMPs) involved in prismatic layer formation were first up-regulated and then gradually down-regulated indicating their involvement in the development of pearl sac and the onset of pearl mineralization. Most of the nacreous layer forming SMPs were up-regulated at 2 weeks after the maturation of pearl sac. Nacrein, MSI7 and shematrin involved in both layer formation were highly expressed during 0 h – 24 h, down-regulated up to 1 week and then up-regulated again after accomplishment of pearl sac formation. Using an RNA-seq approach we unraveled the expression pattern of the key genes involved in the development of pearl sac and pearl as a result of host immune response after grafting. These findings provide valuable information in understanding the molecular mechanism of pearl formation and immune response in P. fucata.
-
Comparison of Two Pearl Sacs Formed in the Same Recipient Oyster with Different Genetic Background Involved in Yellow Pigmentation in Pinctada fucata
Marine Biotechnology, 2018Co-Authors: Mikihiro Shinohara, Shigeharu Kinoshita, Enkong Tang, Daisuke Funabara, Makoto Kakinuma, Kaoru Maeyama, Kiyohito Nagai, Masahiko Awaji, Shugo Watabe, Shuichi AsakawaAbstract:Color is one of the most important factors determining the commercial value of pearls. Pinctada fucata is a well-known pearl oyster producing high-quality Akoya pearls. Phenotypic variation in amount of yellow pigmentation produces white and yellowish pearls. It has been reported that polymorphism of yellow pigmentation of Akoya pearls is genetically regulated, but the responsible gene(s) has remained unknown. Here, we prepared pearl sac pairs formed in the same recipient oyster but coming from donor oysters that differ in their color. These two pearl sacs produced pearls with different yellowness even in the same recipient oyster. Yellow tone of produced pearls was consistent with shell nacre color of donor oysters from which mantle grafts were prepared, indicating that donor oysters strongly contribute to the yellow coloration of Akoya pearls. We also conducted comparative RNA-seq analysis and retrieved several candidate genes involved in the pearl coloration. Whole gene expression patterns of pair sacs were not grouped by pearl color they produced, but grouped by recipient oysters in which they were grown, suggesting that the number of genes involved in the yellow coloration is quite small, and that recipient oyster affects gene expression of the majority of genes in the pearl sac.
-
pearl production by implantation of outer epithelial cells isolated from the mantle of pinctada fucata and the effects of blending of epithelial cells with different genetic backgrounds on pearl quality
2018Co-Authors: Masahiko Awaji, Shigeharu Kinoshita, Makoto Kakinuma, Kaoru Maeyama, Kiyohito Nagai, Takashi Yamamoto, Yasunori Iwahashi, Fumihiro Hattori, Shugo WatabeAbstract:In the current method of pearl production, the mantle fragment of a donor pearl oyster is transplanted into a host pearl oyster together with an inorganic bead (pearl nucleus). After this surgical procedure, only outer epithelial cells (OEC) in the transplanted mantle survive in a host pearl oyster and form a pearl sac to begin pearl formation. Therefore, implantation of only the OEC instead of the mantle fragment would be a possible alternative to the current procedure. To examine the potential of pearl production by implanting OEC in Pinctada fucata, we developed a cell implantation method using the pearl nucleus carrying a small pit inoculated with OEC. As a result, approximately 70% of the inserted nuclei formed the nacreous layer when the OEC were inoculated at 5 × 104 cells/nucleus. Then, OEC isolated from two genetically different types of pearl oysters that significantly differed in shell nacre color (yellowness) were mixed at four different ratios, and the prepared OEC mixtures were transplanted to investigate the effects of the blend on the yellowness of pearls to be harvested. The yellowness of harvested pearls differed significantly in accordance with the mixing ratio. Similarly, OEC isolated from two types of pearl oysters that showed a significant difference in the thickness of their shell nacre aragonite tablets were mixed at four different ratios and transplanted. Mean thickness of the aragonite tablets of the harvested pearls differed according to mixing ratio. These results suggest the method to control pearl quality by blending OEC obtained from pearl oysters genetically improved by selective breeding for traits related to pearl quality.
-
gene expression patterns in the mantle and pearl sac tissues of the pearl oyster pinctada fucata
2018Co-Authors: Shigeharu Kinoshita, Kaoru Maeyama, Kiyohito Nagai, Shuichi Asakawa, Shugo WatabeAbstract:The shell of pearl oysters consists of two distinct layers, nacre and prismatic. Mantle is the tissue involved in the shell formation, and its ventral part (mantle edge) forms the prismatic layers, whereas the dorsal part (pallium) forms the nacre. In pearl culture, mantle grafts from the pallium of donor are transplanted into the recipient. Then pearl sac is formed by proliferation of epithelial cells from the grafted mantle to form pearls. It has been reported that gene expression patterns are different between mantle edge and pallium in accordance with their distinct functions in the shell formation. However, it is not well addressed whether gene expression is identical or not between two nacre-forming tissues, pallium and pearl sac. Here, we examined expression patterns of known genes related to nacre and prismatic layer formation in mantle edge, pallium, and pearl sac of Pinctada fucata. Although the pallium and pearl sac have the same function in terms of nacre formation, various genes were not expressed identically to the respective tissues, suggesting that shell matrix proteins differently function in the formation of shell nacre and pearls.
Chin-long Ky - One of the best experts on this subject based on the ideXlab platform.
-
Cultured Pearl Surface Quality Profiling by the Shell Matrix Protein Gene Expression in the Biomineralised Pearl Sac Tissue of Pinctada margaritifera
Marine Biotechnology, 2018Co-Authors: Carole Blay, Serge Planes, Chin-long KyAbstract:Nucleated pearls are produced by molluscs of the Pinctada genus through the biomineralisation activity of the pearl sac tissue within the recipient oyster. The pearl sac originates from graft tissue taken from the donor oyster mantle and its functioning is crucial in determining key factors that impact pearl quality surface characteristics. The specific role of related gene regulation during gem biogenesis was unknown, so we analysed the expression profiles of eight genes encoding nacreous (PIF, MSI60, PERL1) or prismatic (SHEM5, PRISM, ASP, SHEM9) shell matrix proteins or both (CALC1) in the pearl sac ( N = 211) of Pinctada margaritifera during pearl biogenesis. The pearls and pearl sacs analysed were from a uniform experimental graft with sequential harvests at 3, 6 and 9 months post-grafting. Quality traits of the corresponding pearls were recorded: surface defects, surface deposits and overall quality grade. Results showed that (1) the first 3 months of culture seem crucial for pearl quality surface determination and (2) all the genes ( SHEM5 , PRISM , ASP , SHEM9 ) encoding proteins related to calcite layer formation were over-expressed in the pearl sacs that produced low pearl surface quality. Multivariate regression tree building clearly identified three genes implicated in pearl surface quality, SHEM9 , ASP and PIF . SHEM9 and ASP were clearly implicated in low pearl quality, whereas PIF was implicated in high quality. Results could be used as biomarkers for genetic improvement of P. margaritifera pearl quality and constitute a novel perspective to understanding the molecular mechanism of pearl formation.
-
Phenome of pearl quality traits in the mollusc transplant model Pinctada margaritifera
Scientific Reports, 2018Co-Authors: Chin-long Ky, Virgile Quillien, Floriane Broustal, Claude Soyez, Dominique DevauxAbstract:The bivalve Pinctada margaritifera exhibits three main transplant phenotypes derived from the donor (from which a mantle graft tissue, the saibo , is excised), the recipient (into which the saibo is implanted with a nucleus, leading to the formation of a pearl sac “chimera”) and the cultured pearls themselves. This first phenome study on the species derived from a large experimental graft. Transplant phenotype was assessed at three scales: 1) macro, pearl size, colour, grade, 2) micro, pearl surface microstructure, and 3) molecular, biomineralisation gene expression level in saibo and pearl sac tissues. From donor to pearl, the phenome revealed fine variations of quality traits dependent on the position on the mantle where the saibo was cut, whose variation could overlap with inter-individual donor phenotype differences. A single donor phenotype could therefore produce multiple pearl phenotypes at the scale of the saibo position, mirroring its original activity at the mantle position level and the colour and shape of the shell. This phenome study provides essential information on phenotypic trait architecture enabling us to explore and explain the main biological functions and pave the way for a phenomic project on P. margaritifera that could benefit the pearl industry.