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Erin L. Mcginty - One of the best experts on this subject based on the ideXlab platform.
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Genetic contribution to pearl formation
2011Co-Authors: Erin L. McgintyAbstract:The silver, Pinctada maxima, and black-lip, Pinctada margaritifera, pearl oysters are two commercially important species which produce high-value "South Sea" pearls. Although pearl culture techniques were developed in the early 1950's and have been continually refined, a large proportion of the pearl harvest (~60%) from these two species still fails to be categorised as "gem" quality. The pearling industry stands to benefit substantially from improvements in pearl quality, as it is the proportion of "gem" quality pearls that largely contributes to the profitability of the industry. Despite research into innovative husbandry, nuclei implantation, and optimum grow-out environments, the industry has not seen dramatic increases in the proportion of high quality pearls from harvests. There is, however, the potential for genetic approaches to increase the proportion of "gem" quality pearls produced through selective breeding. Before targeted breeding programs can be developed though, there needs to be a strong understanding of the genetic basis of traits and this is currently lacking for pearls. To date, little research has focussed on the genetic Processes behind pearl formation, a complex Process potentially involving the genetic contribution from two individual oysters (host and donor oyster). Given the complexity of pearl production and the potential genetic contribution from two oyster genomes, without a clear understanding of the role of each oyster in the pearl Biomineralisation Process targeted selection cannot be effective. This thesis defines the respective roles of the host and donor oysters in pearl formation, by first examining their phenotypic contribution to pearl quality traits followed by a fine scale examination of their molecular contribution to the pearl Biomineralisation Process. Prior to genetic improvement of pearl quality through selective breeding, the respective roles the donor and host oysters play in the determination of pearl quality traits must first be defined. Current pearl culture techniques do not permit differentiation between the host and donor oyster pearl phenotypes due to con-specifics being used as the host and donor oyster (allografts). One possible way to provide information on the contribution from the host and donor to pearl traits is by adopting a novel approach of using mantle grafts originating from one pearl oyster species implanted into a second recipient species that is closely related and characteristically has a different pearl phenotype (termed a xenograft). For the first time, this thesis definitively demonstrates the contribution from the donor and host oysters to pearl phenotypic traits through xenotransplantation of two closely related yet distinctly different pearl producing species, P. maxima and P. margaritifera. The results conclusively revealed that the donor oyster is the main contributor to pearl quality. In particular, pearl colour and size were strongly influenced by the donor oyster species used as xenografts. P. maxima donors produced larger, silver colour based pearls, whilst, P. margaritifera xenografts produced smaller, black colour based pearls. Through the novel approach of producing xenografted pearl oysters, this study demonstrates the potential of xenografts as a means to improve pearl quality traits such as pearl size, and highlights the role that donor oysters have in the realisation of pearl growth, colour and surface complexion. In light of phenotypically detecting the donor oyster as the main contributor to pearl quality traits, the next logical question is what is happening at the molecular level in regard to the expression of Biomineralisation related proteins that govern pearl formation. Whilst, studies have shown that genomic DNA from a mantle allograft remains present in the pearl sac at the time of pearl harvest, what remains unclear is whether Biomineralisation genes from the donor mantle allograft are transcriptionally active and contribute to pearl formation. One of the biggest impediments in determining whether the donor or host cells are transcriptionally active for Biomineralisation genes in the pearl sac is discriminating between the gene products of the two potentially contributing oysters. Currently there is insufficient information on levels of intra-specific polymorphisms in putative Biomineralisation genes to characterise gene products that may be derived from the host/donor oysters. This thesis took a powerful and novel approach in determining if the donor oyster cells remain transcriptionally active in the pearl sac, by xenografting two species of pearl oyster, P. maxima and P. margaritifera, which contain species-diagnostic gene differences. Diagnostic PCR tests revealed that donor oyster cells not only remained present in the pearl sac at the time of pearl harvest, but were found for the first time to be transcriptionally active in the expression of two Biomineralisation genes, N44 and N66. These results support that the donor oyster is an important contributor to the Biomineralisation Process in pearl culture. To further elaborate on what is happening at the molecular level in regard to the expression of Biomineralisation related proteins that govern pearl formation, the pearl sac transcriptome of P. maxima and P. margaritifera was examined through high through-put RNA sequencing (Illumina GAII). Allografted and xenografted pearl sacs from two pearl oyster species with unique genomes, P. maxima and P. margaritifera, were produced. Putative molluscan Biomineralisation-related genes identified within the sequenced allografted pearl sacs of both P. maxima and P. margaritifera revealed 19 Biomineralisation genes similarly expressed in both species. This is the largest proportion of genes linked to the Process of Biomineralisation within the pearl sac to date. Based on the presence/absence of species diagnostic gene transcripts within xenografted pearl sacs, all genes examined were found to be expressed by the species used as the donor oyster. In one individual it also found that the host was expressing Linkine. These results convincingly show for the first time that not only is the donor mantle tissue transcriptionally active, it is primarily responsible for the expression of Biomineralisation genes in the pearl sac. Outcomes of this thesis have provided a substantial advancement in the understanding of cultured pearl formation. By understanding the importance of the donor oyster to pearl formation and quality, this research provides grounds for a donor specific selective breeding program based on pearl growth, colour and surface complexion. Now that the major genes potentially involved in pearl Biomineralisation have been identified in this thesis and the donor established as the main contributor to the expression of these genes, the next step is to identify the specific function of these genes that lead to different pearl quality traits. This will ensure pearl quality traits are not only selected upon based purely on phenotype, but an understanding of the molecular mechanisms underlying pearl traits to achieve maximum genetic gains. This thesis not only provides a solid foundation for elucidating the biological Process of pearl formation in general, but it also provides valuable information that can be directly utilised for selective breeding programs in the cultured pearl industry to improve pearl quality.
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Diagnostic genetic markers unravel the interplay between host and donor oyster contribution in cultured pearl formation
Aquaculture, 2011Co-Authors: Erin L. Mcginty, Kyall R. Zenger, Joseph U.u. Taylor, Brad S. Evans, Dean R. JerryAbstract:To produce a cultured pearl, a mantle allograft originating from a donor oyster is surgically implanted along with a shell bead nucleus into the gonad of a recipient oyster from the same species (termed the host oyster). Whilst, studies have shown that genomic DNA from a mantle allograft remains present in the pearl sac at the time of pearl harvest, what remains unclear is whether Biomineralisation genes from the donor mantle allograft are transcriptionally active and contribute to pearl formation. To help resolve the interplay between host and donor genetic contribution in pearl formation, xenografts were produced, using two Pinctada species, P. maxima and P. margaritifera, to examine which species-specific nacreous genes (N66 and N44) were expressed in the pearl sac. Diagnostic DNA tests revealed that donor oyster cells not only remained present in the pearl sac at the time of pearl harvest, but were found for the first time to be transcriptionally active in the expression of Biomineralisation genes, N44 and N66. These results confirm that the donor oyster is an important contributor to the Biomineralisation Process in pearl culture. Understanding the role the donor and host oyster have in cultured pearl formation provides a solid foundation for elucidating the biological Process in general, but it also provides valuable information that can be directly utilised for selective breeding programs in the cultured pearl industry.
Serge Planes - One of the best experts on this subject based on the ideXlab platform.
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Donor and recipient contribution to phenotypic traits and the expression of Biomineralisation genes in the pearl oyster model Pinctada margaritifera
Scientific reports, 2017Co-Authors: Carole Blay, Serge PlanesAbstract:Grafting associates two distinct genotypes, each of which maintains its own genetic identity throughout the life of the grafted organism. Grafting technology is well documented in the plant kingdom, but much less so in animals. The pearl oyster, Pinctada margaritifera, produces valuable pearls as a result of the Biomineralisation Process of a mantle graft from a donor inserted together with a nucleus into the gonad of a recipient oyster. To explore the respective roles of donor and recipient in pearl formation, a uniform experimental graft was designed using donor and recipient oysters monitored for their growth traits. At the same time, phenotypic parameters corresponding to pearl size and quality traits were recorded. Phenotypic interaction analysis demonstrated: 1) a positive correlation between recipient shell biometric parameters and pearl size, 2) an individual donor effect on cultured pearl quality traits. Furthermore, the expressions of Biomineralisation biomarkers encoding proteins in the aragonite or prismatic layer showed: 1) higher gene expression levels of aragonite-related genes in the large donor phenotype in the graft tissue, and 2) correlation of gene expression in the pearl sac tissue with pearl quality traits and recipient biometric parameters. These results emphasize that pearl size is mainly driven by the recipient and that pearl quality traits are mainly driven by the donor.
Yannick Gueguen - One of the best experts on this subject based on the ideXlab platform.
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Impact of pCO2 on the energy, reproduction and growth of the shell of the pearl oyster Pinctada margaritifera
Estuarine Coastal and Shelf Science, 2016Co-Authors: G. Le Moullac, Claude Soyez, Jeremie Vidal-dupiol, Corinne Belliard, Julie Fievet, Manaarii Sham-koua, Alain Lo-yat, Denis Saulnier, Nabila Gaertner-mazouni, Yannick GueguenAbstract:The possible consequences of acidification on pearl farming are disruption of oyster metabolism and change in growth. In the laboratory, we studied the impact of pCO2 (3540, 1338 and 541μatm) on the physiology of pearl oysters exposed for 100 days. This experiment was repeated after an interval of one year. Several physiological compartments were examined in pearl oysters: the scope for growth by measuring ingestion, assimilation and oxygen consumption, gametogenesis by means of histological observations, shell growth by measurement and observation by optical and electronic microscopy, and at molecular level by measuring the expression of nine genes of mantle cells implied in the Biomineralisation Process. Results from both experiments showed that high pCO2 had no effect on scope for growth and gametogenesis. High pCO2 (3540 μatm) significantly slowed down the shell deposit rate at the ventral side and SEM observations of the inside of the shell found signs of chemical dissolution. Of the nine examined genes high pCO2significantly decreased the expression level of one gene (Pmarg-PUSP 6). This study showed that shell growth of the pearl oyster would be slowed down without threatening the species since the management of energy and reproduction functions appeared to be preserved. Further investigations should be conducted on the response of offspring to acidification.
Dean R. Jerry - One of the best experts on this subject based on the ideXlab platform.
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Diagnostic genetic markers unravel the interplay between host and donor oyster contribution in cultured pearl formation
Aquaculture, 2011Co-Authors: Erin L. Mcginty, Kyall R. Zenger, Joseph U.u. Taylor, Brad S. Evans, Dean R. JerryAbstract:To produce a cultured pearl, a mantle allograft originating from a donor oyster is surgically implanted along with a shell bead nucleus into the gonad of a recipient oyster from the same species (termed the host oyster). Whilst, studies have shown that genomic DNA from a mantle allograft remains present in the pearl sac at the time of pearl harvest, what remains unclear is whether Biomineralisation genes from the donor mantle allograft are transcriptionally active and contribute to pearl formation. To help resolve the interplay between host and donor genetic contribution in pearl formation, xenografts were produced, using two Pinctada species, P. maxima and P. margaritifera, to examine which species-specific nacreous genes (N66 and N44) were expressed in the pearl sac. Diagnostic DNA tests revealed that donor oyster cells not only remained present in the pearl sac at the time of pearl harvest, but were found for the first time to be transcriptionally active in the expression of Biomineralisation genes, N44 and N66. These results confirm that the donor oyster is an important contributor to the Biomineralisation Process in pearl culture. Understanding the role the donor and host oyster have in cultured pearl formation provides a solid foundation for elucidating the biological Process in general, but it also provides valuable information that can be directly utilised for selective breeding programs in the cultured pearl industry.
Carole Blay - One of the best experts on this subject based on the ideXlab platform.
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Donor and recipient contribution to phenotypic traits and the expression of Biomineralisation genes in the pearl oyster model Pinctada margaritifera
Scientific reports, 2017Co-Authors: Carole Blay, Serge PlanesAbstract:Grafting associates two distinct genotypes, each of which maintains its own genetic identity throughout the life of the grafted organism. Grafting technology is well documented in the plant kingdom, but much less so in animals. The pearl oyster, Pinctada margaritifera, produces valuable pearls as a result of the Biomineralisation Process of a mantle graft from a donor inserted together with a nucleus into the gonad of a recipient oyster. To explore the respective roles of donor and recipient in pearl formation, a uniform experimental graft was designed using donor and recipient oysters monitored for their growth traits. At the same time, phenotypic parameters corresponding to pearl size and quality traits were recorded. Phenotypic interaction analysis demonstrated: 1) a positive correlation between recipient shell biometric parameters and pearl size, 2) an individual donor effect on cultured pearl quality traits. Furthermore, the expressions of Biomineralisation biomarkers encoding proteins in the aragonite or prismatic layer showed: 1) higher gene expression levels of aragonite-related genes in the large donor phenotype in the graft tissue, and 2) correlation of gene expression in the pearl sac tissue with pearl quality traits and recipient biometric parameters. These results emphasize that pearl size is mainly driven by the recipient and that pearl quality traits are mainly driven by the donor.