The fluted giant clam (Tridacna squamosa) increases the protein abundance of the host's copper-zinc superoxide dismutase in the colorful outer mantle, but not the whitish inner mantle, during light exposure

Chew, Shit F.; Koh, Clarissa Z. Y.; Hiong, Kum C.; Boo, Mel V.; Wong, Wai P.; Ip, Yuen K.

doi:10.1016/j.cbpa.2020.110791

Cited by 4 publications

(6 citation statements)

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“…To supply CO 2 effectively to the photosynthesizing symbionts, the outer mantle of the host possesses a light-enhanced carbon concentration mechanism, which involves iridocytes and tubular epithelial cells, with Vacuolar-type H + -ATPase (VHA; Ip et al, 2018) and Carbonic Anhydrase 2 (CA2; Ip et al, 2017b) as the major catalytic mechanisms. Due to O 2 released by the symbionts, the host needs to augment the detoxification of superoxide radicals (O 2 -) by increasing the expression levels of copper zinc superoxide dismutase (CuZnSOD; Hiong et al, 2018) and manganese superoxide dismutase (MnSOD; Chew et al, 2020) in the outer mantle in response to illumination. The host also conducts light-enhanced inorganic phosphate (P i ) absorption through Sodium-dependent Phosphate Transport protein 2a (NPT2a; and supply it to the photosynthesizing symbionts.…”

Section: Giant Clams Harbor Extracellular Symbionts In a Tubular Systemmentioning

confidence: 99%

“…•− , and the anti-oxidative defense must be more vigorous in light than in darkness (Hiong et al, 2018;Chew et al, 2020). In giant clams, ROS leaking from the photosynthesizing symbionts are unlikely to affect the oxidative status of the host cells directly, because the symbionts are located extracellularly inside the tubular system (Figure 1).…”

Section: The Outer Mantle Needs Light-enhanced Anti-oxidative Defense Mechanisms To Deal With O 2 Produced By Photosynthesizing Symbiontsmentioning

confidence: 99%

“…Most eukaryotic cells express copper-zinc superoxide dismutases (CuZnSODs) in the cytoplasm (Sturtz et al, 2001) and manganese superoxide dismutases (MnSODs) in the mitochondrial matrix (Perry et al, 2010). Recently, the complete cDNA coding sequence of a host-derived CuZnSOD has been obtained from the outer mantle of the T. squamosa (Chew et al, 2020). The protein abundance, but not the transcript level, of CuZnSOD, increases significantly in the outer mantle of T. squamosa after 12 h of light exposure, indicating translational regulation of expression (Table 1; Chew et al, 2020).…”

Section: The Outer Mantle Needs Light-enhanced Anti-oxidative Defense Mechanisms To Deal With O 2 Produced By Photosynthesizing Symbiontsmentioning

confidence: 99%

“…Recently, the complete cDNA coding sequence of a host-derived CuZnSOD has been obtained from the outer mantle of the T. squamosa (Chew et al, 2020). The protein abundance, but not the transcript level, of CuZnSOD, increases significantly in the outer mantle of T. squamosa after 12 h of light exposure, indicating translational regulation of expression (Table 1; Chew et al, 2020). This would probably result in an increased capacity to detoxify O 2…”

Section: The Outer Mantle Needs Light-enhanced Anti-oxidative Defense Mechanisms To Deal With O 2 Produced By Photosynthesizing Symbiontsmentioning

confidence: 99%

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Light-Dependent Phenomena and Related Molecular Mechanisms in Giant Clam-Dinoflagellate Associations: A Review

Chew

2021

Front. Mar. Sci.

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Giant clams can grow to large sizes despite living in oligotrophic waters of the tropical Indo-Pacific as they maintain a mutualistic relationship with symbiotic dinoflagellates (zooxanthellae) and receive photosynthate from them. The phototrophic dinoflagellates live extracellularly inside a tubular system located mainly in the colorful outer mantle and have no access to the ambient seawater. Hence, the clam host needs to absorb exogenous inorganic carbon (Ci), nitrogen (N) and phosphorus (P), and supply them to the symbionts. As photosynthesizing symbionts need more nutrients in light than in the dark, the uptake rates of these exogenous nutrients by the host must increase during illumination, implying that the host’s transporters involved need to be regulated by some kind of light-responsive mechanisms. Furthermore, the growth and development of the host can also be augmented by light, because of the photosynthate donated by the photosynthesizing symbionts. Consequently, giant clams display many light-dependent phenomena related to phototrophy, antioxidative defense, biomineralization, as well as absorption of exogenous Ci, N, and P. These phenomena may involve collaborations among enzymes and transporters in several organs of the host, whereby the gene and protein expression levels of these biocatalysts are up- or down-regulated during illumination. This review aims to examine the molecular mechanisms of light-dependent physiological phenomena that occur in intact giant clam-dinoflagellate associations, and to highlight the differences between giant clams and scleractinian corals in those regards. As the population of giant clams in nature are dwindling due to climate change and anthropogenic activities, a good understanding of their light-dependent processes may generate new ideas to improve their growth and survival under rapidly changing environmental conditions.

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Section: Giant Clams Harbor Extracellular Symbionts In a Tubular Systemmentioning

confidence: 99%

Section: The Outer Mantle Needs Light-enhanced Anti-oxidative Defense Mechanisms To Deal With O 2 Produced By Photosynthesizing Symbiontsmentioning

confidence: 99%

Section: The Outer Mantle Needs Light-enhanced Anti-oxidative Defense Mechanisms To Deal With O 2 Produced By Photosynthesizing Symbiontsmentioning

confidence: 99%

Section: The Outer Mantle Needs Light-enhanced Anti-oxidative Defense Mechanisms To Deal With O 2 Produced By Photosynthesizing Symbiontsmentioning

confidence: 99%

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Light-Dependent Phenomena and Related Molecular Mechanisms in Giant Clam-Dinoflagellate Associations: A Review

Chew

2021

Front. Mar. Sci.

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“…Conversely, a decrease in the activities of these two enzymes might result from their neutralization of highly reactive superoxide radicals with the prolongation of light exposure time. Furthermore, higher SOD activities in the outer mantle were observed compared to those in the inner mantle, which showed the same tendency as T. squamosa (Chew et al 2020).…”

mentioning

confidence: 57%

Effects of the daily light-dark cycle on rhythms of behavior and physiology in boring giant clam Tridacna crocea

Li,

Yang,

Hong

et al. 2024

Preprint

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Giant clams obtain their nutrition from both filter-feeding and photosynthates produced by symbiotic zooxanthellae within their mantle tissue. The symbiotic partnerships between giant clam and zooxanthellae are critical for the health and survival of giant clams. Therefore, light/dark alternation plays a crucial role in influencing the growth performance and physiological change of the giant clam-zooxanthellae symbiosis in natural ecosystems. In this study, the rhythms of mantle area, physiological metabolic activity, and oxidative stress in the boring giant clam, Tridacna crocea, caused by 12-hour light-dark cycles (7:00–19:00 light-on and 9:00–21:00 light-on, respectively) were investigated. The relative mantle area, net calcification rate and gross primary production significantly increased with the increase in light time, and the highest values were observed after 4–7 h of light exposure. The values of symbiosis Y (II) sharply increased when giant clams were transferred from dark to light conditions, and then slightly decreased to a low level until the next light/dark cycle. Dynamic changes of zooxanthellae density in the outer mantle were observed with two-peck values noted at 4-h after light-on and -off, respectively. The absorption of ammonium-nitrogen (negative values of ammonia metabolic rate) was observed when giant clams were exposed to light, and the rate reached its highest value after 10 h of light exposure. Rhythmic changes of oxidative stress related enzymes and antioxidant molecule were also detected in the inner and outer mantles. In detail, the highest values of SOD activity were observed around light-on time in both inner and outer mantles, while the tendency of CAT activity was not the same in inner and outer mantles; the GSH contents in inner mantle were significantly higher than that in outer mantle, and their values significantly increased with light exposure; the MDA concentrations from 5:00 to 14:00 were almost the same in both inner and outer mantles, which showed significantly higher than those of other sampling point. The rhythms of these detected behaviors and physiological responses were almost delayed with the delay of photocycle. This provides experimental support for the hypothesis that some behaviors and physiological responses of giant clams exhibit circadian rhythms, which are affected by change of light/dark alternation.

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Effects of the daily light-dark cycle on rhythms of behavior and physiology in boring giant clam Tridacna crocea

Li,

Yang,

Hong

et al. 2024

Mar Biol

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The fluted giant clam (Tridacna squamosa) increases the protein abundance of the host's copper-zinc superoxide dismutase in the colorful outer mantle, but not the whitish inner mantle, during light exposure

Cited by 4 publications

References 70 publications

Light-Dependent Phenomena and Related Molecular Mechanisms in Giant Clam-Dinoflagellate Associations: A Review

Light-Dependent Phenomena and Related Molecular Mechanisms in Giant Clam-Dinoflagellate Associations: A Review

Effects of the daily light-dark cycle on rhythms of behavior and physiology in boring giant clam Tridacna crocea

Effects of the daily light-dark cycle on rhythms of behavior and physiology in boring giant clam Tridacna crocea

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