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Eastern Oyster Larval Transcriptomes in Response to Probiotic and Pathogenic Bacteria.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Eastern Oyster Larval Transcriptomes in Response to Probiotic and Pathogenic Bacteria./
作者:	Modak, Tejashree.
出版者:	Ann Arbor : ProQuest Dissertations & Theses, : 2018,
面頁冊數:	263 p.
附註:	Source: Dissertations Abstracts International, Volume: 80-06, Section: B.
Contained By:	Dissertations Abstracts International80-06B.
標題:	Molecular biology. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=10976987
ISBN:	9780438705999

Eastern Oyster Larval Transcriptomes in Response to Probiotic and Pathogenic Bacteria.
Modak, Tejashree.

Eastern Oyster Larval Transcriptomes in Response to Probiotic and Pathogenic Bacteria. - Ann Arbor : ProQuest Dissertations & Theses, 2018 - 263 p.

Source: Dissertations Abstracts International, Volume: 80-06, Section: B.

Thesis (Ph.D.)--University of Rhode Island, 2018.

This item is not available from ProQuest Dissertations & Theses.

Oysters are described as keystone species serving an important ecological role. As filter- feeders they help in maintaining water quality. Oyster reefs provide refuge and support to different organisms. The eastern oyster, Crassostrea virginica, native to the East Coast of United States and Gulf of Mexico is a part of the rapidly growing aquaculture industry. Aquaculture production depends on a healthy and constant supply of oyster larvae that are provided by the hatcheries. Several hatcheries on the east coast that provide C. virginica larvae to oyster farms face significant losses owing to Vibrio infections causing massive larval mortalities. Use of antibiotics are avoided due to possibility of development of antibiotic resistance. Probiotics Phaeobacter inhibens S4 and Bacillus pumilus RI06-95 have been shown to successfully protect C. virginica larvae from V. coralliilyticus RE22 infection. Use of these probiotics in hatcheries can reduce the mortalities thereby avoiding economical losses. In order to design best practices for probiotic use it is crucial to understand their mechanism of action. There has been tremendous progress in understanding the components of oyster immune system, its functioning in response to various stimuli and its uniqueness as compared to other organisms. This is partly due to availability of sophisticated tools like high throughput sequencing and various -omics analyses such as proteomics, genomics and transcriptomics and partly due to interest in controlling diseases affecting aquaculture. As such most of our knowledge is based on studies that focus on oyster-pathogen or oyster-environmental stimuli interaction. We know very little about the effect of bacteria other than pathogens on the oysters. We also know very little about larval immunity of eastern oyster, C. virginica. This is the first study to investigate the effect of both pathogen and probiotic bacteria on C. virginica larval immunity using transcriptomes. The aim of this study is to test the safety and efficacy of formulated probiotic Bacillus pumilus RI06-95 in a hatchery, understand the mechanisms of action of both probiotics and to characterize the effect of V. coralliilyticus RE22 infection on larval immune system. Chapter 1 reviews the current knowledge of oyster immune system and the mechanisms of action of probiotics especially mechanisms related to immunomodulation of innate immunity. Previous studies have demonstrated successful protection of C. virginica larvae from V. coralliilyticus RE22 infection in a laboratory based setting as well as in a hatchery using a lab grown culture of probiotics. The ultimate use of the probiotics is in a hatchery with easy to use and stable formulation of the probiotics instead of time consuming lab grown probiotic cultures that are viable for only a short duration of time. Chapter 2 discusses methods of formulation of probiotic Bacillus pumilus RI06-95, testing the formulation in a hatchery and its effect on larval survival at the hatchery and post V. coralliilyticus RE22 challenge. A spray dried formulation of Bacillus pumilus RI06-95 was both shelf-stable and effective in protecting C. virginica larvae from an experimental V. coralliilyticus RE22 challenge. The formulation did not show any adverse effects on the larvae during the course of the trial. Chapter 3 investigates the host-pathogen interaction between C. virginica larvae and V. coralliilyticus RE22 using transcriptomes produced after experimental challenge. It allows better understanding of the disease process caused by V. coralliilyticus RE22. Exposure for 6 hours gave an idea of the changes in host immune system brought about by the pathogen in the early hours of disease. One of the most important virulence factor of the pathogen is protease production. However, at 6 hours the key effector that can counter it, protease inhibitor was not seen to be upregulated. Overall, important immune pathways that produce antimicrobial effectors seemed to be suppressed by V. coralliilyticus RE22. The transcriptomic evidence suggests that lack of an adequate immune response to thwart the infection of RE22 leads to large scale mortalities of C. virginica larvae. Chapter 4 investigates the effect of non-pathogenic and friendly bacteria on the immune system of the host C. virginica, larvae are exposed to probiotic strains Phaeobacter inhibens S4 and Bacillus pumilus RI06-95. It presents evidence of immunomodulation of C. virginica larval immunity by both probiotics. Key immune response of high upregulation of serine protease inhibitors is seen at both early (6h) and late (24h) lab exposure as well as in hatchery trial. Other important modulations that help larvae protect themselves from V. coralliilyticus RE22 infection include activation of pathogen receptors and signaling pathways, modulation of mucin genes and upregulation of pore-forming protein perforin-2. Chapter 5 summarizes and advocates the of use of probiotics in the larviculture of C. virginica and suggests their potential role in limiting vibriosis.

ISBN: 9780438705999Subjects--Topical Terms:

517296
Molecular biology.

Eastern Oyster Larval Transcriptomes in Response to Probiotic and Pathogenic Bacteria.
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520 $a Oysters are described as keystone species serving an important ecological role. As filter- feeders they help in maintaining water quality. Oyster reefs provide refuge and support to different organisms. The eastern oyster, Crassostrea virginica, native to the East Coast of United States and Gulf of Mexico is a part of the rapidly growing aquaculture industry. Aquaculture production depends on a healthy and constant supply of oyster larvae that are provided by the hatcheries. Several hatcheries on the east coast that provide C. virginica larvae to oyster farms face significant losses owing to Vibrio infections causing massive larval mortalities. Use of antibiotics are avoided due to possibility of development of antibiotic resistance. Probiotics Phaeobacter inhibens S4 and Bacillus pumilus RI06-95 have been shown to successfully protect C. virginica larvae from V. coralliilyticus RE22 infection. Use of these probiotics in hatcheries can reduce the mortalities thereby avoiding economical losses. In order to design best practices for probiotic use it is crucial to understand their mechanism of action. There has been tremendous progress in understanding the components of oyster immune system, its functioning in response to various stimuli and its uniqueness as compared to other organisms. This is partly due to availability of sophisticated tools like high throughput sequencing and various -omics analyses such as proteomics, genomics and transcriptomics and partly due to interest in controlling diseases affecting aquaculture. As such most of our knowledge is based on studies that focus on oyster-pathogen or oyster-environmental stimuli interaction. We know very little about the effect of bacteria other than pathogens on the oysters. We also know very little about larval immunity of eastern oyster, C. virginica. This is the first study to investigate the effect of both pathogen and probiotic bacteria on C. virginica larval immunity using transcriptomes. The aim of this study is to test the safety and efficacy of formulated probiotic Bacillus pumilus RI06-95 in a hatchery, understand the mechanisms of action of both probiotics and to characterize the effect of V. coralliilyticus RE22 infection on larval immune system. Chapter 1 reviews the current knowledge of oyster immune system and the mechanisms of action of probiotics especially mechanisms related to immunomodulation of innate immunity. Previous studies have demonstrated successful protection of C. virginica larvae from V. coralliilyticus RE22 infection in a laboratory based setting as well as in a hatchery using a lab grown culture of probiotics. The ultimate use of the probiotics is in a hatchery with easy to use and stable formulation of the probiotics instead of time consuming lab grown probiotic cultures that are viable for only a short duration of time. Chapter 2 discusses methods of formulation of probiotic Bacillus pumilus RI06-95, testing the formulation in a hatchery and its effect on larval survival at the hatchery and post V. coralliilyticus RE22 challenge. A spray dried formulation of Bacillus pumilus RI06-95 was both shelf-stable and effective in protecting C. virginica larvae from an experimental V. coralliilyticus RE22 challenge. The formulation did not show any adverse effects on the larvae during the course of the trial. Chapter 3 investigates the host-pathogen interaction between C. virginica larvae and V. coralliilyticus RE22 using transcriptomes produced after experimental challenge. It allows better understanding of the disease process caused by V. coralliilyticus RE22. Exposure for 6 hours gave an idea of the changes in host immune system brought about by the pathogen in the early hours of disease. One of the most important virulence factor of the pathogen is protease production. However, at 6 hours the key effector that can counter it, protease inhibitor was not seen to be upregulated. Overall, important immune pathways that produce antimicrobial effectors seemed to be suppressed by V. coralliilyticus RE22. The transcriptomic evidence suggests that lack of an adequate immune response to thwart the infection of RE22 leads to large scale mortalities of C. virginica larvae. Chapter 4 investigates the effect of non-pathogenic and friendly bacteria on the immune system of the host C. virginica, larvae are exposed to probiotic strains Phaeobacter inhibens S4 and Bacillus pumilus RI06-95. It presents evidence of immunomodulation of C. virginica larval immunity by both probiotics. Key immune response of high upregulation of serine protease inhibitors is seen at both early (6h) and late (24h) lab exposure as well as in hatchery trial. Other important modulations that help larvae protect themselves from V. coralliilyticus RE22 infection include activation of pathogen receptors and signaling pathways, modulation of mucin genes and upregulation of pore-forming protein perforin-2. Chapter 5 summarizes and advocates the of use of probiotics in the larviculture of C. virginica and suggests their potential role in limiting vibriosis.
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