Light-enhanced expression of Carbonic Anhydrase 4-like supports shell formation in the fluted giant clam Tridacna squamosa

Chew, Shit F.; Koh, Clarissa Z. Y.; Hiong, Kum C.; Choo, Celine Yen Ling; Wong, Wai P.; Neo, Mei Lin; Ip, Yuen K.

doi:10.1016/j.gene.2018.10.023

Cited by 32 publications

(23 citation statements)

References 50 publications

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“…First, it could be an adaptation to effectively harness the urea-carbon for photosynthesis, as symbiotic dinoflagellates no longer have access to the carbon in the ambient seawater. Despite the host's efforts to increase inorganic carbon uptake (Koh et al 2018;Chew et al 2019) and supply it to the symbionts through a host-mediated carbon concentration mechanism (Ip et al 2017, Armstrong et al 2018, it might be essential for these dinoflagellates to capture and fix the ureacarbon directly inside the plastid where photosynthesis occurs. Second, it could be an adaptation of symbiotic dinoflagellates to effectively capture ureanitrogen for amino acid synthesis.…”

Section: Discussionmentioning

confidence: 99%

Symbiodiniaceae Dinoflagellates Express Urease in Three Subcellular Compartments and Upregulate its Expression Levels in situ in Three Organs of a Giant Clam (Tridacna squamosa) During Illumination

Teng

Boo

et al. 2020

Journal of Phycology

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Giant clams harbor three genera of symbiotic dinoflagellates (Symbiodinium, Cladocopium, and Durusdinium) as extracellular symbionts (zooxanthellae). While symbiotic dinoflagellates can synthesize amino acids to benefit the host, they are nitrogen‐deficient. Hence, the host must supply them with nitrogen including urea, which can be degraded to ammonia and carbon dioxide by urease (URE). Here, we report three complete coding cDNA sequences of URE, one for each genus of dinoflagellate, obtained from the colorful outer mantle of the giant clam, Tridacna squamosa. The outer mantle had higher transcript level of Tridacna squamosa zooxanthellae URE (TSZURE) than the whitish inner mantle, foot muscle, hepatopancreas, and ctenidium. TSZURE was immunolocalized strongly and atypically in the plastid, moderately in the cytoplasm, and weakly in the cell wall and plasma membrane of symbiotic dinoflagellates. In the outer mantle, illumination upregulated the protein abundance of TSZURE, which could enhance urea degradation in photosynthesizing dinoflagellates. The urea‐nitrogen released could then augment synthesis of amino acids to be shared with the host for its general needs. Illumination also enhanced gene and protein expression levels of TSZURE/TSZURE in the inner mantle and foot muscle, which contain only small quantities of symbiotic dinoflagellate, have no iridocyte, and lack direct exposure to light. With low phototrophic potential, dinoflagellates in the inner mantle and foot muscle might need to absorb carbohydrates in order to assimilate the urea‐nitrogen into amino acids. Amino acids donated by dinoflagellates to the inner mantle and the foot muscle could be used especially for synthesis of organic matrix needed for light‐enhanced shell formation and muscle protein, respectively.

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Section: Discussionmentioning

confidence: 99%

Symbiodiniaceae Dinoflagellates Express Urease in Three Subcellular Compartments and Upregulate its Expression Levels in situ in Three Organs of a Giant Clam (Tridacna squamosa) During Illumination

Teng

Boo

et al. 2020

Journal of Phycology

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“…In T. squamosa , LEC increases the pH and reduces the ammonia concentration at the interface between the inner mantle and the shell in the extra-pallial fluid, where the biomineralization occurs (Ip et al, 2006). Recently, Chew et al (2019) reported a light-enhanced expression of a carbonic anhydrase (i.e., CA4-like) in the inner mantle of T. squamosa and suggested that this enzyme is involved in giant clam biomineralization by catalyzing the conversion of HCO - to CO 2 . In this context, an altered photophysiology of the symbiont can rationally alter LEC and consequently results in a decrease of the shell growth rate.…”

Section: Discussionmentioning

confidence: 99%

Effects of temperature andpCO₂on the respiration, biomineralization and photophysiology of the giant clamTridacna maxima

Brahmi

Chapron

Moullac

et al. 2019

Preprint

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Such as many other reef organisms, giant clams are today confronted to global change effects and can suffer mass bleaching or mortality events mainly related to abnormally high seawater temperatures. Despite its strong ecological and socio-economical importance, its responses to the two most alarming threats linked to global change (i.e., ocean warming and acidification) still need to be explored. We investigated physiological responses of 4-years-old Tridacna maxima specimens to realistic levels of temperature and partial pressure of carbon dioxide (pCO2) (+1.5°C and +800 μatm of CO2) predicted for 2100 in French Polynesian lagoons during the warmer season. During a 65-days crossed-factor experiment, individuals were exposed to two temperatures (29.2°C; 30.7°C) and two pCO2 (430 µatm; 1212 µatm) conditions. Impact of each parameter and their potential synergetic effect were evaluated on respiration, biomineralization and photophysiology. Kinetics of thermal and acidification stress were evaluated by performing measurements at different times of exposure (29, 41, 53, 65 days). At 30.7°C, the holobiont O2 production, symbiont photosynthetic yield, and density were negatively impacted. High pCO2 had a significant negative effect on shell growth rate, symbiont photosynthetic yield and density. Shell microstructural modifications were observed from 41 days in all temperature and pCO2 conditions. No significant synergetic effect was found. Today thermal conditions (29.2°C) appeared to be sufficiently stressful to induce a host acclimatization process. All these observations indicate that temperature and pCO2 are both forcing variables affecting T. maxima physiology and jeopardize its survival under environmental conditions predicted for the end of this century.

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“…Porites compressa (Kuffner, 2001). However, recent findings for hermatypic corals also report that the contribution by the symbionts might not be the primary or sole driver for LEC, but the blue light spectrum could trigger the light sensors of the host itself, leading to higher calcification rates (Cohen et al, 2016). It is suggested that blue light photoreceptors in coral tissues of Porites lutea and Acropora variabilis could potentially sense the light which is ultimately activating a cascade of processes involved in blue light-enhanced calcification (Cohen et al, 2016).…”

Section: Light-dependent Calcification and Production In Red Sea Gianmentioning

confidence: 99%

Light-dependent calcification in Red Sea giant clam <i>Tridacna maxima</i>

et al. 2019

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Abstract. Tropical giant clams of the subfamily Tridacninae, including the species Tridacna maxima, are unique among bivalves as they live in a symbiotic relationship with unicellular algae and generally function as net photoautotrophs. Light is therefore crucial for these species to thrive. Here we examine the light dependency of calcification rates of T. maxima in the central Red Sea as well as the patterns of its abundance with depth in the field. Red Sea T. maxima show the highest densities at a depth of 3 m with 0.82±0.21 and 0.11±0.03 individuals m−2 (mean ± SE) at sheltered and exposed sites, respectively. Experimental assessment of net calcification (µmol CaCO3 cm−2 h−1) and gross primary production (µmol O2 cm−2 h−1) under seven light levels (1061, 959, 561, 530, 358, 244, and 197 µmol quanta m−2 s−1) showed net calcification rates to be significantly enhanced under light intensities corresponding to a water depth of 4 m (0.65±0.03 µmol CaCO3 cm−2 h−1; mean ± SE), while gross primary production was 2.06±0.24 µmol O2 cm−2 h−1 (mean ± SE). We found a quadratic relationship between net calcification and tissue dry mass (DM in gram), with clams of an intermediate size (about 15 g DM) showing the highest calcification. Our results show that the Red Sea giant clam T. maxima stands out among bivalves as a remarkable calcifier, displaying calcification rates comparable to other tropical photosymbiotic reef organisms such as corals.

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Light-enhanced expression of Carbonic Anhydrase 4-like supports shell formation in the fluted giant clam Tridacna squamosa

Cited by 32 publications

References 50 publications

Symbiodiniaceae Dinoflagellates Express Urease in Three Subcellular Compartments and Upregulate its Expression Levels in situ in Three Organs of a Giant Clam (Tridacna squamosa) During Illumination

Symbiodiniaceae Dinoflagellates Express Urease in Three Subcellular Compartments and Upregulate its Expression Levels in situ in Three Organs of a Giant Clam (Tridacna squamosa) During Illumination

Effects of temperature andpCO₂on the respiration, biomineralization and photophysiology of the giant clamTridacna maxima

Light-dependent calcification in Red Sea giant clam <i>Tridacna maxima</i>

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Light-enhanced expression of Carbonic Anhydrase 4-like supports shell formation in the fluted giant clam Tridacna squamosa

Cited by 32 publications

References 50 publications

Symbiodiniaceae Dinoflagellates Express Urease in Three Subcellular Compartments and Upregulate its Expression Levels in situ in Three Organs of a Giant Clam (Tridacna squamosa) During Illumination

Symbiodiniaceae Dinoflagellates Express Urease in Three Subcellular Compartments and Upregulate its Expression Levels in situ in Three Organs of a Giant Clam (Tridacna squamosa) During Illumination

Effects of temperature andpCO2on the respiration, biomineralization and photophysiology of the giant clamTridacna maxima

Light-dependent calcification in Red Sea giant clam &lt;i&gt;Tridacna maxima&lt;/i&gt;

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Effects of temperature andpCO₂on the respiration, biomineralization and photophysiology of the giant clamTridacna maxima

Light-dependent calcification in Red Sea giant clam <i>Tridacna maxima</i>