Quantification of algal endosymbionts (<i>Symbiodinium</i>) in coral tissue using real‐time PCR

Mieog, Jos C.; Oppen, Madeleine J. H. van; Berkelmans, Ray; Stam, Wytze T.; Olsen, Jeanine L.

doi:10.1111/j.1755-0998.2008.02222.x

Cited by 91 publications

(93 citation statements)

References 34 publications

(75 reference statements)

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“…Likewise, using zooxanthella Clade D-specific primers for an actin-coding gene (GenBank Accession No. EU312078-80) (Mieog et al 2009) on the pooled coral mRNA samples also tested negative for contamination stemming from zooxanthellar genomic DNA (data not shown). This, and the fact that the internal control genes (ICG) had very similar C t values when normalised to total mRNA (see below), indicates that contamination with zooxanthellar mRNA was also negligible.…”

Section: Methodsmentioning

confidence: 93%

Variation in antioxidant gene expression in the scleractinian coral Acropora millepora under laboratory thermal stress

Császár¹,

Seneca²,

Oppen³

2009

Mar. Ecol. Prog. Ser.

100

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The effects of climate change over the last few decades have pushed the majority of reef-building corals close to their upper thermal limit. Upon exposure to thermal stress, the intracellular formation of harmful oxygen intermediates can lead to the disruption of the obligate symbiosis between the coral host and their dinoflagellate endosymbionts (zooxanthellae), a process known as coral bleaching. Applications of molecular techniques to cnidarian research have recently enhanced our understanding of the magnitude of corals' transcriptional response to various stressors. In the present study, we developed a quantitative real-time polymerase chain reaction assay to assess expression levels of 4 genes involved in the corals' oxidative stress response (HSP70, MnSOD, ferritin, Zn 2+ -metalloprotease) after exposure to laboratory-controlled thermal stress. Using the IndoPacific reef coral Acropora millepora, our study provides the first population-scale analysis of antioxidant gene expression in coral. Despite the significant up-regulation of those 4 genes in the thermally stressed samples relative to non-stressed samples, our results show that there is an enormous intraas well as inter-colony variation in transcript abundance at a particular point in time. We discuss the potential roles of ferritin and Zn 2+-metalloprotease in the break down of the intra-cellular Fe 2+ -homeostasis and in coral host cell detachment, respectively, during bleaching conditions. Our results emphasise the importance of measuring inter-individual variation to gain an insight into the population response to a common and increasingly encountered environmental stressor.

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Section: Methodsmentioning

confidence: 93%

Variation in antioxidant gene expression in the scleractinian coral Acropora millepora under laboratory thermal stress

Császár¹,

Seneca²,

Oppen³

2009

Mar. Ecol. Prog. Ser.

100

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“…C T values for O. faveolata and Symbiodinium clade B were reduced by 5.74 and 5.41 cycles, respectively, to normalize differences in fluorescent signal intensity among assays, based on the results of standard curves generated following the methods of Cunning & Baker [34]. Adjusted C T values were then used to calculate symbiont to host (S/H) cell ratios [33] using the formula 2 CT(host)2CT(symbiont) , divided by the symbiont to host ploidy ratio (1/2 [37]), DNA extraction efficiency ratio (0.828 [34]) and target locus copy number ratio (see below).…”

Section: (F ) Symbiont Quantificationmentioning

confidence: 99%

“…Because symbiont types differ not only in heat tolerance, but also in photosynthetic performance [14,30], energetics [31] and associated coral growth rates [13,15], overall symbiosis function should be determined by the contributions of all symbionts [32]. However, the functional consequences of variation in symbiont community composition are poorly understood, in part because molecular methods to quantify mixed assemblages have only recently been developed [33,34]. Here, we apply these methods to conduct a quantitative investigation of the links between symbiont community structure and function, and the drivers of community change following disturbance.…”

Section: Introductionmentioning

confidence: 99%

Investigating the causes and consequences of symbiont shuffling in a multi-partner reef coral symbiosis under environmental change

2015

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Dynamic symbioses may critically mediate impacts of climate change on diverse organisms, with repercussions for ecosystem persistence in some cases. On coral reefs, increases in heat-tolerant symbionts after thermal bleaching can reduce coral susceptibility to future stress. However, the relevance of this adaptive response is equivocal owing to conflicting reports of symbiont stability and change. We help reconcile this conflict by showing that change in symbiont community composition (symbiont shuffling) in Orbicella faveolata depends on the disturbance severity and recovery environment. The proportion of heat-tolerant symbionts dramatically increased following severe experimental bleaching, especially in a warmer recovery environment, but tended to decrease if bleaching was less severe. These patterns can be explained by variation in symbiont performance in the changing microenvironments created by differentially bleached host tissues. Furthermore, higher proportions of heat-tolerant symbionts linearly increased bleaching resistance but reduced photochemical efficiency, suggesting that any change in community structure oppositely impacts performance and stress tolerance. Therefore, even minor symbiont shuffling can adaptively benefit corals, although fitness effects of resulting trade-offs are difficult to predict. This work helps elucidate causes and consequences of dynamism in symbiosis, which is critical to predicting responses of multi-partner symbioses such as O. faveolata to environmental change.

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“…In the cooling treatment, samples were collected at the start (24°C), and at the end of weeks 4 (20°C), 6 (18°C) and 9 (15°C). The symbiont to host (S/H) cell ratio (Mieog et al, 2009) for Symbiodinium clades C and D was measured using quantitative PCR assays for actin loci specific to each Symbiodinium clade (Cunning and Baker, 2013) and M. cavernosa, following methods described in Silverstein et al (2015). Cycle threshold (C T ) values were normalized for fluorophore intensity and gene copy number, averaged among technical replicates, and used to calculate S/H ratios with the formula 2 C T;host ÀC T;symbiont .…”

Section: Symbiont Community Structurementioning

confidence: 99%

Tenacious D: Symbiodinium in clade D remain in reef corals at both high and low temperature extremes despite impairment

Silverstein

Cunning

Baker

2017

Journal of Experimental Biology

100

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Reef corals are sensitive to thermal stress, which induces coral bleaching (the loss of algal symbionts), often leading to coral mortality. However, corals hosting certain symbionts (notably some members of Symbiodinium clade D) resist bleaching when exposed to high temperatures. To determine whether these symbionts are also cold tolerant, we exposed corals hosting either Symbiodinium C3 or D1a to incremental warming (+1°C week −1 to 35°C) and cooling (−1°C week −1 to 15°C), and measured photodamage and symbiont loss. During warming to 33°C, C3 corals were photodamaged and lost >99% of symbionts, while D1a corals experienced photodamage but did not bleach. During cooling, D1a corals suffered more photodamage than C3 corals but still did not bleach, while C3 corals lost 94% of symbionts. These results indicate that photodamage does not always lead to bleaching, suggesting alternate mechanisms exist by which symbionts resist bleaching, and helping explain the persistence of D1a symbionts on recently bleached reefs, with implications for the future of these ecosystems.

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Quantification of algal endosymbionts (Symbiodinium) in coral tissue using real‐time PCR

Cited by 91 publications

References 34 publications

Variation in antioxidant gene expression in the scleractinian coral Acropora millepora under laboratory thermal stress

Variation in antioxidant gene expression in the scleractinian coral Acropora millepora under laboratory thermal stress

Investigating the causes and consequences of symbiont shuffling in a multi-partner reef coral symbiosis under environmental change

Tenacious D: Symbiodinium in clade D remain in reef corals at both high and low temperature extremes despite impairment

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