The Experts below are selected from a list of 12729 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, Damian Hine, Max Wingfield, Tuikolongahau Halafihi, 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 mabe pearl production in the western pacific
Aquaculture, 2020Co-Authors: Bill Johnston, Pranesh Kishore, Damian Hine, Gary Bingnald Vuibeqa, Paul C SouthgateAbstract: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
Akira Komaru - One of the best experts on this subject based on the ideXlab platform.
-
nacre growth and thickness of akoya Pearls from japanese and hybrid pinctada fucata in response to the aquaculture temperature condition in ago bay japan
Aquaculture, 2017Co-Authors: Gunawan Muhammad, Takashi Atsumi, Akira KomaruAbstract:Abstract This study examines whole nacre thickness and monthly growth of Pearls of Akoya pearl oyster, Pinctada fucata , which came from Japanese and hybrid strains and relate them to the water temperature of the aquaculture site in Ago Bay. Whole nacre thickness of the Pearls was significantly different between Japanese and Hybrid strains (Student's t -test, p -value t -test, p -value t -test, p -value Statement of relevance The findings of this study will redound to the benefit of commercial aquaculture of pearl oyster in the world generally, and in Japan especially considering that cultured pearl is one of the important aquaculture products in Japan and some other Countries.
-
post operative care of implanted pearl oysters pinctada fucata in low salinity seawater improves the quality of Pearls
Aquaculture, 2014Co-Authors: Takashi Atsumi, Nariaki Inoue, Naoaki Kamiya, Hideo Aoki, Ryo Ishibashi, Takashi Ishikawa, Akira KomaruAbstract:Current techniques for culturing the Akoya pearl oyster Pinctada fucata result in low yields of blemish-free, round Pearls (high-quality Pearls). We compared the effects of five factors on the proportion of high-quality Pearls produced during culture using a generalized linear model (GLM). Two factors were physiological, shell-closing strength (SCS) and the whole wet weight of host pearl oysters, and three factors were procedural, post-operative care method, technician, and nucleus diameter. Our results suggest that post-operative care methods have the most significant effect on increasing the proportion of high-quality Pearls. The proportion of high-quality Pearls was five-fold higher in the group held in low salinity seawater than in the conventional treatment group. We propose a new post-operative care method in which oysters are immersed in low salinity seawater to increase the production of high-quality Pearls.
-
Can the Quality of Pearls from the Japanese Pearl Oyster (Pinctada fucata) be Explained by the Gene Expression Patterns of the Major Shell Matrix Proteins in the Pearl Sac?
Marine Biotechnology, 2011Co-Authors: Nariaki Inoue, Takashi Atsumi, Hideo Aoki, Ryo Ishibashi, Takashi Ishikawa, Akira KomaruAbstract:For pearl culture, the pearl oyster is forced open and a nucleus is implanted into the gonad with a mantle graft. The outer mantle epithelial cells of the implanted mantle graft elongate and surrounding the nucleus a pearl sac is formed. Shell matrix proteins secreted by the pearl sac play an important role in the regulation of pearl formation. Recently, seven shell matrix proteins were identified from the pearl oyster Pinctada fucata . However, there is a paucity of information on the function of these proteins and their gene expression patterns. Our study aims to elucidate the relationship between pearl type, quality, and gene expression patterns of six shell matrix proteins ( msi60 , n16 , nacrein , msi31 , prismalin-14 , and aspein ) in the pearl sac based on real-time PCR analysis. After culturing for about 2 months, the pearl sac tissues were collected from 22 individuals: 12 with high quality (HP), nine with low quality (LP), and one with organic (ORG) pearl formation. The surface of each of the 12 HP Pearls was composed only of a nacreous layer; in contrast, that of the nine LP Pearls was composed of nacreous and prismatic layers. The six target gene expressions were detected in all individuals. However, delta threshold cycle (Δ C _T) for msi31 was significantly higher in the HP than in the LP individuals (Mann–Whitney’s U test, p = 0.02). This means that the relative expression level of msi31 , which constitutes the framework of the prismatic layer, was higher in the LP than in the HP individuals.
-
color and weight of Pearls produced by grafting the mantle tissue from a selected population for white shell color of the japanese pearl oyster pinctada fucata martensii dunker
Aquaculture, 1996Co-Authors: K T Wada, Akira KomaruAbstract:Abstract Pearl color and weight were investigated by transplanting mantle tissue from specimens selected for white shell color in the prismatic layer in order to obtain information for selective breeding of the Japanese pearl oyster Pinctada fucata martensii . The frequency of yellow Pearls was significantly lower in the group produced by grafting mantle tissue from the inbred white line than from brown lines in two experiments. Pearl weight did not differ between the two groups produced by grafting mantle tissue of white or brown types of donor. Positive correlation was observed between the weight of Pearls and that of the shell of host oysters. These results have implications for the selective breeding of host and donor pearl oysters.
Pranesh Kishore - One of the best experts on this subject based on the ideXlab platform.
-
economic assessment of community based pearl oyster spat collection and mabe pearl production in the western pacific
Aquaculture, 2020Co-Authors: Bill Johnston, Pranesh Kishore, Damian Hine, Gary Bingnald Vuibeqa, Paul C SouthgateAbstract: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.
-
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
-
a detailed description of pearl sac development in the black lip pearl oyster pinctada margaritifera linnaeus 1758
Aquaculture Research, 2016Co-Authors: Pranesh Kishore, Paul C SouthgateAbstract:Appropriate development of the pearl-sac in pearl oysters is an important factor influencing the quality of cultured Pearls. In this study, a total of 110 black-lip pearl oysters (Pinctada margaritifera) with a mean (± SE) antero-posterior measurement of 110.82 ± 0.41 mm and dorso-ventral measurement of 112.06 ± 0.45 mm were grafted to allow histological examination and chronological description of pearl-sac development in this species. Beginning 2 days after grafting, oysters were sacrificed regularly until the 48th day and the pearl-sacs of sampled oysters were sectioned and examined. Graft tissue proliferated and developed into a complete pearl-sac within 14 days of grafting when the epithelial cells responsible for nacre secretion were fully developed. However, first nacre secretion onto the nucleus was not observed until 32 days after grafting. The presence and accumulation of haemocytes in the pearl pouch initially and in the pearl-sac thereafter is one of the primary factors potentially affecting pearl quality. Clumps of haemocytes present between the pearl-sac and nucleus caused distension of the pearl-sac from an ideally spherical shape. Furthermore, the presence of byssus in close proximity to the developing pearl-sac was demonstrated in this study. This has the potential to impact pearl-sac formation and resulting pearl quality. The findings reported in this paper provide a more detailed understanding of pearl-sac development in P. margaritifera and a basis for future research towards developing improved pearl culture practices and pearl quality.
-
the effect of different culture methods on the quality of round Pearls produced by the black lip pearl oyster pinctada margaritifera linnaeus 1758
Aquaculture, 2016Co-Authors: Pranesh Kishore, Paul C SouthgateAbstract:Abstract A range of culture units and husbandry methods may be used for pearl oysters and the two most commonly used for Pinctada margaritifera are panel nets and chaplets. In this study, six hundred P. margaritifera were grafted for the first time and cultured using panel nets or chaplets at three commercial farm sites to determine if these different culture methods influences resulting pearl quality. The Pearls produced were compared in terms of size, shape, lustre, colour, surface perfection and overall quality. The highest proportion of Pearls produced in all treatments was in the 10–11 mm size category (37–54%) but culture method did not significantly (p = 0.211) influence the size of Pearls produced. Oysters held on chaplets produced more Pearls with concentric surface grooves or ‘circles’ (47–60%) compared to oysters in held panel nets (43–45%) at all three culture sites. Oysters held in panel nets produced higher proportions of Pearls in the more desirable ‘round’ and ‘semi-round’ shape categories (6% and 25%, respectively) than oysters held on chaplets (5% and 15%, respectively) at all three culture sites, and culture method had a significant impact (p = 0.031) on pearl shape overall. Higher proportions of Pearls in the ‘very high’ and ‘high’ lustre categories (8% and 40%, respectively) were produced by oysters held in panel nets compared to those on chaplets (3% and 16%, respectively) at each of the three culture sites. However, the overall impact of culture methods on pearl lustre was not significant (p = 0.100). At all three culture sites, higher proportions of Pearls assigned to grades ‘A’ (6%) and ‘B’ (46%) were produced by oysters in panel nets compared to those held on chaplets where 3% and 29% of Pearls were assigned to grade ‘A’ and grade ‘B’, respectively. Oysters held on chaplets produced higher proportions of grade ‘C’ (49%) and grade ‘D’ (19%) Pearls than those in panel nets (39% and 9%, respectively) at all three culture sites. The grades of Pearls were significantly influenced (p = 0.035) by culture method. This study clearly demonstrated the benefits of pearl production using panel nets compared to the traditional chaplet-based system used by the majority of pearl farmers in Fiji and throughout the Pacific. Pearls production using panel nets will provide better returns with higher profit margins for pearl farmers but requires greater outlay for infrastructure and labour that may be beyond the scope of most pearl farmers in Fiji and the Pacific. A detailed cost–benefit analysis of the two husbandry options would be beneficial to pearl farmers. Statement of relevance This paper presents novel new information showing that grafted P. margaritifera cultured using panel nets produced Pearls with fewer ‘circles’ and of higher quality and value than oysters cultured using chaplets. The potential benefits to pearl farmers of pearl production using panel nets compared to the more traditional chaplet-based system are clear and the results of this study support improved pearl quality and income for pearl farmers in the Pacific.
Carole Blay - One of the best experts on this subject based on the ideXlab platform.
-
Relationship of the orange tissue morphotype with shell and pearl colouration in the mollusc Pinctada margaritifera.
Scientific Reports, 2019Co-Authors: Carole Blay, Manaarii Sham Koua, Floriane Broustal, Serge PlanesAbstract:Molluscs display a vast range of shell colours both between and within species. However, only a few species show colour variation in their soft tissues. In French Polynesia, the pearl oyster Pinctada margaritifera has three tissue morphotypes: the black wild-type and two rare mutations: white albino and orange mantle. Phenotypic transmission is known to occur from these phenotypes when they are used as graft donors for pearl production, leading to multicoloured and white Pearls from black and albino mantle grafts, respectively. The present study furthers this knowledge by examining the phenotypic association between the orange mantle tissue morphotype and hard tissues: shells and cultured Pearls. Based on a large experimental graft, shell colour quantification and pearl qualification showed that the orange morphotype is associated with light-coloured shells and Pearls. Expression analysis of some candidate genes previously identified in the white mantle mutant, tested here on both graft and pearl sac tissues from orange mantle donors, confirmed the involvement of genes associated with shell matrix protein (shem4) and the melanin biosynthesis pathway (zinc). This study provides fundamental information on the mechanism behind mantle tissue colour in P. margaritifera and its association with biomineralisation and pigmentation processes that will be potentially valuable in future selection programs.
-
crossing phenotype heritability and candidate gene expression in grafted black lipped pearl oyster pinctada margaritifera an animal chimera
Journal of Heredity, 2018Co-Authors: Carole Blay, Serge PlanesAbstract:Grafting mantle tissue of a donor pearl oyster into the gonad of a recipient oyster results in the formation of a chimera, the pearl sac. The phenotypic variations of this chimera are hypothesized to be the result of interactions between the donor and recipient genomes. In this study, the heritability of phenotypic variation and its association with gene expression were investigated for the first time during Pinctada margaritifera pearl production. Genetic variance was evaluated at different levels, 1) before the graft operation (expression in graft tissue), 2) after grafting (pearl sac tissue expression in chimera), and 3) on the product of the graft (pearl phenotype traits) based on controlled biparental crosses and the F1 generation. Donor-related genetic parameter estimates clearly demonstrate heritability for nacre weight and thickness, darkness and color, and surface defects and grade, which signifies a genetic basis in the donor oyster. In graft relative gene expression, the value of heritability was superior to 0.20 in for almost all genes; whereas in pearl sac, heritability estimates were low (h2 < 0.10; except for CALC1 and Aspein). Pearl sac expression seems to be more influenced by residual variance than the graft, which can be explained by environmental effects that influence Pearls sac gene expression and act as a recipient additive genetic component. The interactions between donor and recipient are very complex, and further research is required to understand the role of the recipient oysters on pearl phenotypic and gene expression variances.
-
Optimal age of the donor graft tissue in relation to cultured pearl phenotypes in the mollusc, Pinctada margaritifera.
PLOS ONE, 2018Co-Authors: Carole Blay, Serge PlanesAbstract:Ageing is defined as the progressive decline in tissue and organ functions over time. This study aims to evaluate the ageing effect on cultured pearl quality phenotypes (including size and quality traits) in the graft-recipient animal model: Pinctada margaritifera. For this, eight uniform grafting experiments were designed using two hatchery-produced pearl oyster families as donors, which were followed through time, between 7 and 30 months in age. For each age category, 20 donors were studied for each culture site giving a total of 2400 grafted oysters. Several phenotypic measurements were made: 1) donor family growth performance from shell size records, 2) pearl size and corresponding quality traits, and 3) expression of some genes related to biomineralization processes on both the mantle graft and on pearl sac tissues. Results showed that: 1) donor age has an impact on pearl size, with grafts coming from the youngest donors yielding the biggest Pearls; and 2) grafts from donors between 12 and 18 months in age produced Pearls of the highest quality (grade and surface quality), a result supported by an analysis where the level of expression for a panel of genes associated with biomineralization was greatest in donors within the 12 to 18 months age group. These results indicate that donors aged between 12 and 18 months have high potential for biomineralisation and nacre deposition, and likely produce larger and higher quality cultured Pearls than older donors.
-
age dependence of cultured pearl grade and colour in the black lipped pearl oyster pinctada margaritifera
Aquaculture Research, 2017Co-Authors: Jonathan Demmer, Carole BlayAbstract:Pinctada margaritifera is an economically important marine bivalve species for cultured pearl production in French Polynesian aquaculture. In order to evaluate the influence of donor oyster age on pearl quality traits, experiments were conducted over 6 years using both grafts and surgreffe operations. At harvest, 6 pearl quality traits were recorded and compared: surface defects, luster, grade, darkness level, and visual color. Analyzing the quality traits of Pearls harvested in the initial graft process and those of Pearls obtained from surgreffe experiments allowed a comparison of the influence of pearl sac cells originating from the initial mantle graft, which aged together with their recipient oysters. The results demonstrated a significant decrease between these successive grafts in luster, grade (A-B-C,) darkness level, and green color – traits that are of major importance in the pearl market. The duplicated graft experiment allowed the comparison of donor oyster families at 2 and 5 years old, where a mantle graft was inserted into recipient oysters aged 2.5 years old. The results showed the same tendencies to a lesser extent, with 1) an improved pearl grade, predominantly through a most important rate of 0 surface defect category, and 2) a green / grey ratio in favor of the younger donor. A comparison between the graft-surgreffe and the duplicated graft experiments also highlighted: 1) the indirect role played by the younger recipient oysters, which must be optimized for optimal pearl quality realization, and 2) the complex interplay between donor and recipient oysters.
-
Macro-geographical differences influenced by family-based expression on cultured pearl grade, shape and colour in the black-lip ‘pearl oyster’ Pinctada margaritifera: a preliminary bi-local case study in French Polynesia
Aquaculture Research, 2017Co-Authors: Carole Blay, Philippe Cabral, Vaite Aiho, Gilles Le MoullacAbstract:n French Polynesia, the aquaculture of Pinctada margaritifera is carried out in numerous grow-out sites, located over three archipelagos (Gambier, Society and Tuamotu). To evaluate the impact of macro-geographical effects of these growing sites on pearl quality traits, five hatcheries produced families were used as homogeneous donor oysters in an experimental graft. The molluscs were then reared in two commercial locations: Tahaa Island (Society) and Rangiroa atoll (Tuamotu). At harvest, eight pearl quality traits were recorded and compared: surface defects, lustre, grade, circles, shape categories, darkness level, body and secondary colour and visual colour categories. Overall inter-site comparison revealed that: (1) all traits were affected by grow-out location except for lustre and round shape, and (2) a higher mean rate of valuable Pearls was produced in Rangiroa. Indeed, for pearl grade, Rangiroa showed twice as many A-B and less reject samples than Tahaa. This was related to the number of surface defects (grade component): in Rangiroa, twice as many Pearls had no defects and less Pearls had up to 10 defects. Concerning pearl shape, more circled and baroque Pearls were found in Tahaa (+10%). For colour variation, 10% more Pearls have an attractive green overtone in Rangiroa than in Tahaa, where more grey body colour were harvested. Lustre does not seem to be affected by these two culture site (except at a family scale). This is the first time P. margaritifera donor family have been shown to vary in the quality of Pearls they produce depending on their grow-out location.
Serge Planes - One of the best experts on this subject based on the ideXlab platform.
-
Relationship of the orange tissue morphotype with shell and pearl colouration in the mollusc Pinctada margaritifera.
Scientific Reports, 2019Co-Authors: Carole Blay, Manaarii Sham Koua, Floriane Broustal, Serge PlanesAbstract:Molluscs display a vast range of shell colours both between and within species. However, only a few species show colour variation in their soft tissues. In French Polynesia, the pearl oyster Pinctada margaritifera has three tissue morphotypes: the black wild-type and two rare mutations: white albino and orange mantle. Phenotypic transmission is known to occur from these phenotypes when they are used as graft donors for pearl production, leading to multicoloured and white Pearls from black and albino mantle grafts, respectively. The present study furthers this knowledge by examining the phenotypic association between the orange mantle tissue morphotype and hard tissues: shells and cultured Pearls. Based on a large experimental graft, shell colour quantification and pearl qualification showed that the orange morphotype is associated with light-coloured shells and Pearls. Expression analysis of some candidate genes previously identified in the white mantle mutant, tested here on both graft and pearl sac tissues from orange mantle donors, confirmed the involvement of genes associated with shell matrix protein (shem4) and the melanin biosynthesis pathway (zinc). This study provides fundamental information on the mechanism behind mantle tissue colour in P. margaritifera and its association with biomineralisation and pigmentation processes that will be potentially valuable in future selection programs.
-
crossing phenotype heritability and candidate gene expression in grafted black lipped pearl oyster pinctada margaritifera an animal chimera
Journal of Heredity, 2018Co-Authors: Carole Blay, Serge PlanesAbstract:Grafting mantle tissue of a donor pearl oyster into the gonad of a recipient oyster results in the formation of a chimera, the pearl sac. The phenotypic variations of this chimera are hypothesized to be the result of interactions between the donor and recipient genomes. In this study, the heritability of phenotypic variation and its association with gene expression were investigated for the first time during Pinctada margaritifera pearl production. Genetic variance was evaluated at different levels, 1) before the graft operation (expression in graft tissue), 2) after grafting (pearl sac tissue expression in chimera), and 3) on the product of the graft (pearl phenotype traits) based on controlled biparental crosses and the F1 generation. Donor-related genetic parameter estimates clearly demonstrate heritability for nacre weight and thickness, darkness and color, and surface defects and grade, which signifies a genetic basis in the donor oyster. In graft relative gene expression, the value of heritability was superior to 0.20 in for almost all genes; whereas in pearl sac, heritability estimates were low (h2 < 0.10; except for CALC1 and Aspein). Pearl sac expression seems to be more influenced by residual variance than the graft, which can be explained by environmental effects that influence Pearls sac gene expression and act as a recipient additive genetic component. The interactions between donor and recipient are very complex, and further research is required to understand the role of the recipient oysters on pearl phenotypic and gene expression variances.
-
Optimal age of the donor graft tissue in relation to cultured pearl phenotypes in the mollusc, Pinctada margaritifera.
PLOS ONE, 2018Co-Authors: Carole Blay, Serge PlanesAbstract:Ageing is defined as the progressive decline in tissue and organ functions over time. This study aims to evaluate the ageing effect on cultured pearl quality phenotypes (including size and quality traits) in the graft-recipient animal model: Pinctada margaritifera. For this, eight uniform grafting experiments were designed using two hatchery-produced pearl oyster families as donors, which were followed through time, between 7 and 30 months in age. For each age category, 20 donors were studied for each culture site giving a total of 2400 grafted oysters. Several phenotypic measurements were made: 1) donor family growth performance from shell size records, 2) pearl size and corresponding quality traits, and 3) expression of some genes related to biomineralization processes on both the mantle graft and on pearl sac tissues. Results showed that: 1) donor age has an impact on pearl size, with grafts coming from the youngest donors yielding the biggest Pearls; and 2) grafts from donors between 12 and 18 months in age produced Pearls of the highest quality (grade and surface quality), a result supported by an analysis where the level of expression for a panel of genes associated with biomineralization was greatest in donors within the 12 to 18 months age group. These results indicate that donors aged between 12 and 18 months have high potential for biomineralisation and nacre deposition, and likely produce larger and higher quality cultured Pearls than older donors.
-
Mono- and polychromatic inner shell phenotype diversity in Pinctada margaritifera donor pearl oysters and its relation with cultured pearl colour
Aquaculture, 2017Co-Authors: Serge PlanesAbstract:The pearl oyster Pinctada margaritifera has the specific ability to produce Pearls with the widest range of colours among all pearl oyster species. This pearl colour diversity originates from the mantle biomineralising tissue (graft) of the donor oyster, which is originally responsible for the variety of colours of the inner shell surface. This study aimed to: 1) assess the geographic distribution and establish a first stocklist of the colourful oyster phenotypes used as donors in French Polynesia, and 2) investigate the phenotypic relation between inner shell colouration and the corresponding colour of harvested Pearls. With the support of a pearl farmers' network, we investigated the different donor phenotype frequencies among five collection sites (Ahe, Apataki, Takaroa, TakumeandMangareva). This donor evaluation was made during grafting of pearl oysters (N=49,938) obtained from collector stations. Results showed that pearl production is mainly based on six common colourful donor phenotypes classified as monochromatic and polychromatic profiles, which shown different frequencies among the collection sites. Experimental grafts (N=4640)were then realised and subsequent culture conducted at a single site in order to avoid pearl colour variation due to environmental influences. Traceability between donors (N=232) and Pearls (N=2776), revealed that: 1) yellow (gold) and aubergine (reddish) Pearls could be mostly obtained by using the monochromatic yellowand red donor phenotypes, respectively, and 2) one third to one quarter of grey Pearlswas inevitably harvested, whatever the polychromatic phenotype chosen as the donor, which leaves at least half the harvest composed of the attractive green and peacock colours. This preliminary stocklist of colour range together with analysis of the colour phenotype transmission between inner shell and pearl provide the basis for producing multiple pearl oyster “colour lines” through hatchery propagation and would be helpful for future selective breeding programs. Statement of relevance: Donor shell colour selection predict colours of Pearls
