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Genetic bases of immunity and disease resistance to White Band Disease in the Caribbean Staghorn coral Acropora cervicornis.

Record Type:	Language materials, manuscript : Monograph/item
Title/Author:	Genetic bases of immunity and disease resistance to White Band Disease in the Caribbean Staghorn coral Acropora cervicornis./
Author:	Libro, Silvia.
Description:	1 online resource (113 pages)
Notes:	Source: Dissertations Abstracts International, Volume: 76-07, Section: B.
Contained By:	Dissertations Abstracts International76-07B.
Subject:	Genetics. -
Online resource:	click for full text (PQDT)
ISBN:	9781321420135

Genetic bases of immunity and disease resistance to White Band Disease in the Caribbean Staghorn coral Acropora cervicornis.
Libro, Silvia.

Genetic bases of immunity and disease resistance to White Band Disease in the Caribbean Staghorn coral Acropora cervicornis. - 1 online resource (113 pages)

Source: Dissertations Abstracts International, Volume: 76-07, Section: B.

Thesis (Ph.D.)--Northeastern University, 2015.

Includes bibliographical references

Over the past thirty years, marine disease outbreaks have increased significantly, producing dramatic alterations in marine ecosystems worldwide. Reef-building corals have been particularly vulnerable to the increase in new epizootic diseases, and yet many aspects of the coral-pathogen interaction remain unresolved, including how corals respond to disease infections. One example is represented by White Band Disease (WBD), a coral disease that causes rapid tissue degradation in acroporid corals. Since the 1970's, WBD outbreaks have caused catastrophic mass mortalities of two foundation species on Caribbean coral reefs, the staghorn coral Acropora cervicornis and the elkhorn coral A. palmata, which populations have collapsed by up to 98%. The etiology of WBD has not been fully elucidated yet, but presence of disease resistant genotypes and local recovery from WBD in natural populations of A. cervicornis suggest that staghorn corals have the ability to fight the disease and that genetic mechanisms may underlie resistance to WBD. My thesis focuses on understanding the genetic basis of coral host immunity and resistance to WBD in the endangered staghorn coral Acropora cervicornis using next-generation sequencing (RNA-seq). To identify the key mediators of the immune response of staghorn corals to WBD disease, I conducted transcriptome analysis of healthy and WBD-infected staghorn corals from natural populations. My results show that WBD causes expression changes in 4% of the coral host transcriptome, and that the immune response to staghorn corals is characterized by pathogen recognition, production of reactive oxygen species, apoptosis and stress response genes, as well as eicosanoids, a class of lipid metabolites including leukotrienes and prostaglandins, that had not previously identified as immune mediators in scleractinian corals. Using common garden experiments, I exposed resistant and susceptible corals to healthy and to WBD-infected grafts to identify expression changes associated to resistance during disease exposure (WBD grafts) and allorecognition (healthy grafts). I found that expression patterns associated to disease resistance are independent from exposure to WBD and do not include any of the immune pathways involved in the response against WBD corals. Rather, the gene expression signature of WBD resistance encompasses a very small number of genes that are constitutively up- or down-regulated in resistant corals. Mechanisms involved in WBD resistance include RNA interference-mediated post-transcriptional regulation, antiviral defense and heat stress response, suggesting a link between thermal stress tolerance and disease resistance. Expression changes associated to exposure revealed that allorecognition only induces expression changes for a small subset of genes involved in general stress response and nematocyst discharge, while exposure to WBD has a large-scale effect on the transcriptome. Consistent with the results described above, disease exposure resulted in enhanced pathogen recognition, synthesis of ROS and production of eicosanoids. Hallmarks of early stage response to WBD included Toll-like receptors (TLR)-mediated NF-kB signaling, Prophenolxidase activity and increased expression of Heath shock proteins and antivirals. These results also show that eicosanoids in staghorn corals are involved in the response to WBD but not to allogeneic tissue exposure and mechanical injury, indicating a pivotal role during pathogen infections rather than during wound repair and general stress response. Taken together, these results indicate that A. cervicornis mounts a powerful response against disease infections involving several innate immune pathways. In addition, this response does not appear to be a general immune response, as indicated by the highly divergent expression profiles of corals exposed to WBD and healthy grafts, suggesting that A. cervicornis is able to discriminate between pathogen attack and allorecognition. By characterizing the genetic signature of resistance to WBD, this research represents a valuable contribution to understanding how corals respond to disease and can serve as a conservation tool to identify and farm WBD-resistant genotypes for large scale restoration of the endangered Caribbean Acropora. This knowledge is critical to the conservation of threatened reef corals and has direct conservation implications for the endangered Caribbean staghorn coral A. cervicornis.

Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2024

Mode of access: World Wide Web

ISBN: 9781321420135Subjects--Topical Terms:

578972
Genetics.
Subjects--Index Terms:

Allene oxideIndex Terms--Genre/Form:

554714
Electronic books.

Genetic bases of immunity and disease resistance to White Band Disease in the Caribbean Staghorn coral Acropora cervicornis.
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500 $a Advisor: Vollmer, Steven V.
502 $a Thesis (Ph.D.)--Northeastern University, 2015.
504 $a Includes bibliographical references
520 $a Over the past thirty years, marine disease outbreaks have increased significantly, producing dramatic alterations in marine ecosystems worldwide. Reef-building corals have been particularly vulnerable to the increase in new epizootic diseases, and yet many aspects of the coral-pathogen interaction remain unresolved, including how corals respond to disease infections. One example is represented by White Band Disease (WBD), a coral disease that causes rapid tissue degradation in acroporid corals. Since the 1970's, WBD outbreaks have caused catastrophic mass mortalities of two foundation species on Caribbean coral reefs, the staghorn coral Acropora cervicornis and the elkhorn coral A. palmata, which populations have collapsed by up to 98%. The etiology of WBD has not been fully elucidated yet, but presence of disease resistant genotypes and local recovery from WBD in natural populations of A. cervicornis suggest that staghorn corals have the ability to fight the disease and that genetic mechanisms may underlie resistance to WBD. My thesis focuses on understanding the genetic basis of coral host immunity and resistance to WBD in the endangered staghorn coral Acropora cervicornis using next-generation sequencing (RNA-seq). To identify the key mediators of the immune response of staghorn corals to WBD disease, I conducted transcriptome analysis of healthy and WBD-infected staghorn corals from natural populations. My results show that WBD causes expression changes in 4% of the coral host transcriptome, and that the immune response to staghorn corals is characterized by pathogen recognition, production of reactive oxygen species, apoptosis and stress response genes, as well as eicosanoids, a class of lipid metabolites including leukotrienes and prostaglandins, that had not previously identified as immune mediators in scleractinian corals. Using common garden experiments, I exposed resistant and susceptible corals to healthy and to WBD-infected grafts to identify expression changes associated to resistance during disease exposure (WBD grafts) and allorecognition (healthy grafts). I found that expression patterns associated to disease resistance are independent from exposure to WBD and do not include any of the immune pathways involved in the response against WBD corals. Rather, the gene expression signature of WBD resistance encompasses a very small number of genes that are constitutively up- or down-regulated in resistant corals. Mechanisms involved in WBD resistance include RNA interference-mediated post-transcriptional regulation, antiviral defense and heat stress response, suggesting a link between thermal stress tolerance and disease resistance. Expression changes associated to exposure revealed that allorecognition only induces expression changes for a small subset of genes involved in general stress response and nematocyst discharge, while exposure to WBD has a large-scale effect on the transcriptome. Consistent with the results described above, disease exposure resulted in enhanced pathogen recognition, synthesis of ROS and production of eicosanoids. Hallmarks of early stage response to WBD included Toll-like receptors (TLR)-mediated NF-kB signaling, Prophenolxidase activity and increased expression of Heath shock proteins and antivirals. These results also show that eicosanoids in staghorn corals are involved in the response to WBD but not to allogeneic tissue exposure and mechanical injury, indicating a pivotal role during pathogen infections rather than during wound repair and general stress response. Taken together, these results indicate that A. cervicornis mounts a powerful response against disease infections involving several innate immune pathways. In addition, this response does not appear to be a general immune response, as indicated by the highly divergent expression profiles of corals exposed to WBD and healthy grafts, suggesting that A. cervicornis is able to discriminate between pathogen attack and allorecognition. By characterizing the genetic signature of resistance to WBD, this research represents a valuable contribution to understanding how corals respond to disease and can serve as a conservation tool to identify and farm WBD-resistant genotypes for large scale restoration of the endangered Caribbean Acropora. This knowledge is critical to the conservation of threatened reef corals and has direct conservation implications for the endangered Caribbean staghorn coral A. cervicornis.
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653 $a Allene oxide
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653 $a Heat shock proteins
653 $a Transcriptomic
653 $a White band disease
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