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.

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.