Molecular characterization, immunofluorescent localization, and expression levels of two bicarbonate anion transporters in the whitish mantle of the giant clam, Tridacna squamosa, and the implications for light-enhanced shell formation.

Giant clams conduct light-enhanced shell formation, which requires the increased transport of Ca and inorganic carbon (C) from the hemolymph through the shell-facing epithelium of the whitish inner mantle to the extrapallial fluid where CaCO deposition occurs. The major form of C in the hemolymph is HCO, but the mechanisms of HCO transport through the basolateral and apical membranes of the shell-facing epithelial cells remain unknown. This study aimed to clone from the inner mantle of Tridacna squamosa the complete coding cDNA sequences of electrogenic Na-HCOcotransporter 1 homolog (NBCe1-like-b) and electrogenic Na-HCOcotransporter 2 homolog (NBCe2-like).

The colorful mantle of the giant clam Tridacna squamosa expresses a homolog of electrogenic sodium: Bicarbonate cotransporter 2 that mediates the supply of inorganic carbon to photosynthesizing symbionts.

Giant clams live in symbiosis with phototrophic dinoflagellates, which reside extracellularly inside zooxanthellal tubules located mainly in the colourful and extensible outer mantle. As symbiotic dinoflagellates have no access to the ambient seawater, they need to obtain inorganic carbon (Ci) from the host for photosynthesis during illumination. The outer mantle has a host-mediated and light-dependent carbon-concentrating mechanism to augment the supply of Ci to the symbionts during illumination.

Basolateral Na/Ca exchanger 1 and Na/K-ATPase, which display light-enhanced gene and protein expression levels, could be involved in the absorption of exogenous Ca through the ctenidium of the giant clam, Tridacna squamosa.

Giant clams perform light-enhanced shell formation (calcification) and therefore need to increase the uptake of exogenous Ca during illumination. The ctenidium of the fluted giant clam, Tridacna squamosa, is involved in light-enhanced Ca uptake. It expresses the pore-forming voltage-gated calcium channel (VGCC) subunit alpha 1 (CACNA1) in the apical membrane of the epithelial cells, and the protein expression level of CACNA1 is upregulated in the ctenidium during illumination.

Using glutamine synthetase 1 to evaluate the symbionts' potential of ammonia assimilation and their responses to illumination in five organs of the giant clam, Tridacna squamosa.

Nitrogen-deficient symbiotic dinoflagellates (zooxanthellae) living inside the fluted giant clam, Tridacna squamosa, need to obtain nitrogen from the host. Glutamine synthetase 1 (GS1) is a cytosolic enzyme that assimilates ammonia into glutamine. We determined the transcript levels of zooxanthellal GS1 (Zoox-GS1), which represented comprehensively GS1 transcripts of Symbiodinium, Cladocopium and Durusdinium, in five organs of T.

Illumination enhances the protein abundance of sarcoplasmic reticulum Ca-ATPases-like transporter in the ctenidium and whitish inner mantle of the giant clam, Tridacna squamosa, to augment exogenous Ca uptake and shell formation, respectively.

The fluted giant clam, Tridacna squamosa, can perform light-enhanced shell formation, aided by its symbiotic dinoflagellates (Symbiodinium, Cladocopium, Durusdinium), which are able to donate organic nutrients to the host. During light-enhanced shell formation, increased Ca transport from the hemolymph through the shell-facing epithelium of the inner mantle to the extrapallial fluid, where calcification occurs, is necessary. Additionally, there must be increased absorption of exogenous Ca from the surrounding seawater, across the epithelial cells of the ctenidium (gill) into the hemolymph, to supply sufficient Ca for light-enhanced shell formation.

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.

The colorful outer mantle of giant clams contains abundance of symbiotic dinoflagellates (zooxanthellae) and iridocytes, and has direct exposure to light. In light, photosynthesizing dinoflagellates produce O, and the host cells in the outer mantle would be confronted with hyperoxia-related oxidative stress. In comparison, the whitish inner mantle contains few symbiotic dinoflagellates and no iridocytes.

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.

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).

Calcium absorption in the fluted giant clam, Tridacna squamosa, may involve a homolog of voltage-gated calcium channel subunit α1 (CACNA1) that has an apical localization and displays light-enhanced protein expression in the ctenidium.

In light, giant clams can increase rates of shell formation and growth due to their symbiotic relationship with phototrophic zooxanthellae residing extracellularly in a tubular system. Light-enhanced shell formation necessitates increase in the uptake of Ca from the ambient seawater and the supply of Ca through the hemolymph to the extrapallial fluid, where calcification occurs. In this study, the complete coding cDNA sequence of a homolog of voltage-gated calcium channel subunit α1 (CACNA1), which is the pore-forming subunit of L-type voltage-gated calcium channels (VGCCs), was obtained from the ctenidium (gill) of the giant clam, Tridacna squamosa.

Increased apical sodium-dependent glucose transporter abundance in the ctenidium of the giant clam upon illumination.

Giant clams contain phototrophic zooxanthellae, and live in nutrient-deficient tropical waters where light is available. We obtained the complete cDNA coding sequence of a homolog of mammalian sodium/glucose cotransporter 1 () from the ctenidium of the fluted giant clam, had a host origin and was expressed predominantly in the ctenidium. Molecular characterizations reveal that SGLT1-like of could transport urea, in addition to glucose, as other SGLT1s do.

Molecular characterization, cellular localization, and light-enhanced expression of Beta-Na/H Exchanger-like in the whitish inner mantle of the giant clam, Tridacna squamosa, denote its role in light-enhanced shell formation.

The fluted giant clam, Tridacna squamosa, lives in symbiosis with photosynthetic zooxanthellae, and can engage in light-enhanced growth and shell formation. Light-enhanced shell formation necessitates the elimination of excess H from the extrapallial fluid adjacent to the shell. This study aimed to clone Na/HExchanger (NHE) from the whitish inner mantle adjacent to the extrapallial fluid of T.

The ctenidium of the giant clam, Tridacna squamosa, expresses an ammonium transporter 1 that displays light-suppressed gene and protein expression and may be involved in ammonia excretion.

Ammonium transporters (AMTs) can participate in ammonia uptake or excretion across the plasma membrane of prokaryotic, plant and invertebrate cells. The giant clam, Tridacna squamosa, harbors nitrogen-deficient symbiotic zooxanthellae, and normally conducts light-enhanced ammonia absorption to benefit the symbionts. Nonetheless, it can excrete ammonia when there is a supply of exogenous nitrogen or exposed to continuous darkness.

Molecular Characterization of a Dual Domain Carbonic Anhydrase From the Ctenidium of the Giant Clam, , and Its Expression Levels After Light Exposure, Cellular Localization, and Possible Role in the Uptake of Exogenous Inorganic Carbon.

A () had been sequenced and characterized from the ctenidia (gills) of the giant clam, , which lives in symbiosis with zooxanthellae. was expressed predominantly in the ctenidium. The complete cDNA coding sequence of from comprised 1,803 bp, encoding a protein of 601 amino acids and 66.

Molecular characterization, light-dependent expression, and cellular localization of a host vacuolar-type H-ATPase (VHA) subunit A in the giant clam, Tridacna squamosa, indicate the involvement of the host VHA in the uptake of inorganic carbon and its supply to the symbiotic zooxanthellae.

The giant clam, Tridacna squamosa, represents a clam-zooxanthellae association. In light, the host clam and the symbiotic zooxanthellae conduct light-enhanced calcification and photosynthesis, respectively. We had cloned the cDNA coding sequence of a Vacuolar-type Proton ATPase (VHA) subunit A, ATP6V1A, from T.

Light exposure enhances urea absorption in the fluted giant clam, , and up-regulates the protein abundance of a light-dependent urea active transporter, DUR3-like, in its ctenidium.

Giant clams live in nutrient-poor reef waters of the Indo-Pacific and rely on symbiotic dinoflagellates ( spp., also known as zooxanthellae) for nutrients. As the symbionts are nitrogen deficient, the host clam has to absorb exogenous nitrogen and supply it to them.

Carbonic anhydrase 2-like in the giant clam, : characterization, localization, response to light, and possible role in the transport of inorganic carbon from the host to its symbionts.

The fluted giant clam, , lives in symbiosis with zooxanthellae which reside extracellularly inside a tubular system. Zooxanthellae fix inorganic carbon (C) during insolation and donate photosynthate to the host. Carbonic anhydrases catalyze the interconversion of CO and HCO3-, of which carbonic anhydrase 2 (CA2) is the most ubiquitous and involved in many biological processes.

The Whitish Inner Mantle of the Giant Clam, , Expresses an Apical Plasma Membrane Ca-ATPase (PMCA) Which Displays Light-Dependent Gene and Protein Expressions.

Giant clams live in symbiosis with extracellular zooxanthellae and display high rates of growth and shell formation (calcification) in light. Light-enhanced calcification requires an increase in the supply of Ca to, and simultaneously an augmented removal of H from, the extrapallial fluid where shell formation occurs. We have obtained the complete coding cDNA sequence of () from the thin and whitish inner mantle, which is in touch with the extrapallial fluid, of the giant clam .

The inner mantle of the giant clam, Tridacna squamosa, expresses a basolateral Na+/K+-ATPase α-subunit, which displays light-dependent gene and protein expression along the shell-facing epithelium.

Na+/K+-ATPase (NKA) is essential for maintaining the Na+ and K+ gradients, and supporting the secondary active transport of certain ions/molecules, across the plasma membrane of animal cells. This study aimed to clone the NKA α-subunit (NKAα) from the inner mantle adjacent to the extrapallial fluid of Tridacna squamosa, to determine its subcellular localization, and to examine the effects of light exposure on its transcript level and protein abundance. The cDNA coding sequence of NKAα from T.

Light-dependent expression of a Na/H exchanger 3-like transporter in the ctenidium of the giant clam, , can be related to increased H excretion during light-enhanced calcification.

Na/H exchangers (NHEs) regulate intracellular pH and ionic balance by mediating H efflux in exchange for Na uptake in a 1:1 stoichiometry. This study aimed to obtain from the ctenidium of the giant clam () the complete cDNA sequence of a (), and to determine the effect of light exposure on its mRNA expression level and protein abundance therein. The coding sequence of comprised 2886 bp, encoding 961 amino acids with an estimated molecular mass of 105.

Voltage-Gated Na+ Channel Isoforms and Their mRNA Expression Levels and Protein Abundance in Three Electric Organs and the Skeletal Muscle of the Electric Eel Electrophorus electricus.

This study aimed to obtain the coding cDNA sequences of voltage-gated Na+ channel (scn) α-subunit (scna) and β-subunit (scnb) isoforms from, and to quantify their transcript levels in, the main electric organ (EO), Hunter's EO, Sach's EO and the skeletal muscle (SM) of the electric eel, Electrophorus electricus, which can generate both high and low voltage electric organ discharges (EODs). The full coding sequences of two scna (scn4aa and scn4ab) and three scnb (scn1b, scn2b and scn4b) were identified for the first time (except scn4aa) in E. electricus.

Aestivation induces changes in transcription and translation of coagulation factor II and fibrinogen gamma chain in the liver of the African lungfish Protopterus annectens.

This study aimed to sequence and characterize two pro-coagulant genes, coagulation factor II (f2) and fibrinogen gamma chain (fgg), from the liver of the African lungfish Protopterus annectens, and to determine their hepatic mRNA expression levels during three phases of aestivation. The protein abundance of F2 and Fgg in the liver and plasma was determined by immunoblotting. The results indicated that F2 and Fgg of P.

Light induces changes in activities of Na(+)/K(+)-ATPase, H(+)/K(+)-ATPase and glutamine synthetase in tissues involved directly or indirectly in light-enhanced calcification in the giant clam, Tridacna squamosa.

The objective of this study was to determine the effects of 12 h of exposure to light, as compared with 12 h of exposure to darkness (control), on enzymatic activities of transporters involved in the transport of NH(+) 4 or H(+), and activities of enzymes involved in converting NH(+) 4 to glutamate/glutamine in inner mantle, outer mantle, and ctenidia of the giant clam, Tridacna squamosa. Exposure to light resulted in a significant increase in the effectiveness of NH(+) 4 in substitution for K(+) to activate Na(+)/K(+)-ATPase (NKA), manifested as a significant increase in the Na(+)/NH(+) 4-activated-NKA activity in the inner mantle. However, similar phenomena were not observed in the extensible outer mantle, which contained abundant symbiotic zooxanthellae.

Na+/K+-ATPase α-subunit (nkaα) isoforms and their mRNA expression levels, overall Nkaα protein abundance, and kinetic properties of Nka in the skeletal muscle and three electric organs of the electric eel, Electrophorus electricus.

This study aimed to obtain the coding cDNA sequences of Na+/K+-ATPase α (nkaα) isoforms from, and to quantify their mRNA expression in, the skeletal muscle (SM), the main electric organ (EO), the Hunter's EO and the Sach's EO of the electric eel, Electrophorus electricus. Four nkaα isoforms (nkaα1c1, nkaα1c2, nkaα2 and nkaα3) were obtained from the SM and the EOs of E. electricus.