Reduced salinity, but not estuarine acidification, is a cause of immune-suppression in the Sydney rock oyster Saccostrea glomerata

Green, Timothy J.; Barnes, Andrew C.

doi:10.3354/meps08430

Cited by 25 publications

(11 citation statements)

References 45 publications

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“…In order to limit the impact of environmental parameters on immune gene expression levels [25,26] similar environmental conditions (see below) and high quality seawater was used for oyster breeding. These oysters were presumed to be healthy because none died during this six-month observation period.…”

Section: Oystersmentioning

confidence: 99%

Vibriosis induced by experimental cohabitation in Crassostrea gigas: Evidence of early infection and down-expression of immune-related genes

Decker

Saulnier

2011

Fish & Shellfish Immunology

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The understanding of reciprocal interactions between Crassostrea gigas and Vibrio sp., whether these be virulent or avirulent, is vital for the development of methods to improve the health status of cultured oysters. We describe an original non-invasive experimental infection technique using cohabitation, designed to explore these interactions. Using real-time PCR techniques we examined the dynamics of virulent and avirulent Vibrio sp. in oyster hemolymph and tank seawater, and made a parallel study of the expression of four genes involved in oyster immune defense: Cg-BPI, Cg-EcSOD, Cg-IκB, Cg-TIMP. No mortality occurred in control animals, but oysters put in cohabitation for 2-48 h with animals previously infected by two Vibrio pathogens suffered mortalities from 2 to 16 days post-cohabitation. Our results show that virulent Vibrio infect healthy individuals after only 2 h of cohabitation, with values ranging from 4.5 x 10² to 2 x 10⁴ cells ml⁻¹ hemolymph. Simultaneously, an approximate ten-fold increase of the total Vibrio population was observed in control animals, with a 6.6-78.5-fold up-expression of targeted genes. In contrast, oysters exposed to harmful bacteria had mean expression levels strongly down-regulated by a factor of 9.2-29 (depending on the gene) compared with control animals. Although oysters were still found to be infected by virulent Vibrio after 6-48 h of cohabitation, no significant differences were noted when comparing levels of each transcript in control and infected oysters at the same sampling times during this period: the important differences were noted before 6 h cohabitation. Taken together, our data support (1) the hypothesis that virulent Vibrio disturbs the immune response of this invertebrate host both rapidly and significantly, although this occurs specifically during an early and transient period during the first 6 h of cohabitation challenge, and that (2) expression of targeted genes is not correlated with vibriosis resistance.

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Section: Oystersmentioning

confidence: 99%

Vibriosis induced by experimental cohabitation in Crassostrea gigas: Evidence of early infection and down-expression of immune-related genes

Decker

Saulnier

2011

Fish & Shellfish Immunology

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“…Thus, the transcription of a Pacific oyster PRDX6 was increased by pollution [50], whereas a 1-Cys PRDX was down regulated in Pseudopleuronectes americanus injected with hexavalent chromium [51], but a PRDX was up-regulated in Platichthys flesus injected with cadmium [52]. The expression of a 2-Cys PRDX gene was enhanced by acute hypo-osmotic stress in the crustacean Eurypanopeus depressus [53], whereas the oyster Saccostrea glomerata exposed to reduced salinity had a lower PRDX6 mRNA expression [54]. Thermal stress increased transcripts levels of PRDX4 and PRDX5 in a bivalve [55] and protein levels of a non-specified NKEF in gilthead sea bream [56].…”

Section: Discussionmentioning

confidence: 99%

Molecular characterization and expression analysis of six peroxiredoxin paralogous genes in gilthead sea bream (Sparus aurata): Insights from fish exposed to dietary, pathogen and confinement stressors

Pérez‐Sánchez

Bermejo-Nogales

Calduch-Giner

et al. 2011

Fish & Shellfish Immunology

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ABSTRACT. The aim of this work was to underline the physiological role of the antioxidant peroxiredoxin (PRDX) family in gilthead sea bream (Sparus aurata L.), a perciform fish extensively cultured in the Mediterranean area. First, extensive BLAST searches were done on the gilthead sea bream cDNA database of the AQUAMAX European Project (www.sigenae.org/iats), and six contigs were unequivocally identified as PRDX1-6 after sequence completion by RT-PCR. The phylogenetic analysis evidenced three major clades corresponding to PRDX1-4 (true 2-Cyst PRDX subclass), PRDX5 (atypical 2-Cys PRDX subclass) and PRDX6 (1-Cys PRDX subclass) that reflected the present hierarchy of vertebrates. However, the PRDX2 branch of modern fish including gilthead sea bream was related to the monophyletic PRDX1 node rather than to PRDX2 cluster of mammals and primitive fish, which probably denotes the acquisition of novel functions through vertebrate evolution. Transcriptional studies by means of quantitative real-time PCR evidenced a ubiquitous PRDX gene expression that was tissue-specific for each PRDX isoform. In a second set of transcriptional studies, liver and head kidney were chosen as target tissues in fish challenged with i) the intestinal parasite Enteromyxum leei, ii) a plant oil (VO) diet with deficiencies in essential fatty acids and iii) prolonged exposure to high rearing densities. These studies showed that PRDX genes were highly and mostly constitutively expressed in the liver and were not affected by dietary intervention or high density. In contrast, head kidney was highly sensitive to the different experimental challenges: significantly lower values were found for PRDX5 in the three trials, for PRDX6 in parasitized and high density fish and for PRDX1 in parasitized and VO fish. PRDX2, 3 and 5 were decreased only in VO, high density and parasitized animals, respectively. These findings would highlight the role of PRDXs as integrative and highly predictive biomarkers of health and welfare in fish and gilthead sea bream in particular.

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“…This also accounts for the generally lower salinity observed in Berrys Bay (< 30 ppt) for the entire study period, a level which would not be considered optimal for Bonamia parasites (Audemard et al 2008) or winter mortality disease (Wolf 1967), which has traditionally been associated with high (30−35 ppt) salinities (Farley et al 1988). Nonetheless, the large fluctuations in salinity observed at this site during June of 2010 were unlikely to be favourable for oyster health, given that low salinities result in immune suppression in Saccostrea glomerata (Butt et al 2006, Green & Barnes 2010.…”

Section: Discussionmentioning

confidence: 99%

Longitudinal study of winter mortality disease in Sydney rock oysters Saccostrea glomerata

Spiers¹,

Gabor²,

Fell³

et al. 2014

Dis. Aquat. Org.

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Winter mortality (WM) is a poorly studied disease affecting Sydney rock oysters Saccostrea glomerata in estuaries in New South Wales, Australia, where it can cause significant losses. WM is more severe in oysters cultured deeper in the water column and appears linked to higher salinities. Current dogma is that WM is caused by the microcell parasite Bonamia roughleyi, but evidence linking clinical signs and histopathology to molecular data identifying bonamiasis is lacking. We conducted a longitudinal study between February and November 2010 in 2 estuaries where WM has occurred (Georges and Shoalhaven Rivers). Results from molecular testing of experimental oysters for Bonamia spp. were compared to clinical disease signs and histopathology. Available environmental data from the study sites were also collated and compared. Oyster condition declined over the study period, coinciding with decreasing water temperatures, and was inversely correlated with the presence of histological lesions. While mortalities occurred in both estuaries, only oysters from the Georges River study site showed gross clinical signs and histological changes characteristic of WM (lesions were prevalent and intralesional microcell-like structures were sometimes noted). PCR testing for Bonamia spp. revealed the presence of an organism belonging to the B. exitiosa−B. roughleyi clade in some samples; however, the very low prevalence of this organism relative to histological changes and the lack of reactivity of affected oysters in subsequent in situ hybridisation experiments led us to conclude that this Bonamia sp. is not responsible for WM. Another aetiological agent and a confluence of environmental factors are a more likely explanation for the disease.

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Reduced salinity, but not estuarine acidification, is a cause of immune-suppression in the Sydney rock oyster Saccostrea glomerata

Cited by 25 publications

References 45 publications

Vibriosis induced by experimental cohabitation in Crassostrea gigas: Evidence of early infection and down-expression of immune-related genes

Vibriosis induced by experimental cohabitation in Crassostrea gigas: Evidence of early infection and down-expression of immune-related genes

Molecular characterization and expression analysis of six peroxiredoxin paralogous genes in gilthead sea bream (Sparus aurata): Insights from fish exposed to dietary, pathogen and confinement stressors

Longitudinal study of winter mortality disease in Sydney rock oysters Saccostrea glomerata

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