Light induces changes in activities of Na+/K+(NH4+)-ATPase, H+/K+(NH4+)-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 NH4+ or H+, and activities of enzymes involved in converting NH4+ to glutamate/glutamin...
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| Format: | Article |
| Language: | English |
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Frontiers Media S.A.
2015-03-01
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| Series: | Frontiers in Physiology |
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| Online Access: | http://journal.frontiersin.org/Journal/10.3389/fphys.2015.00068/full |
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| author | Alex Y K Ip Alex Y K Ip Biyun eChing Biyun eChing Kum C. Hiong Kum C. Hiong Yen Ling eChoo Mel Veen Boo WaiP eWong S F Chew |
| author_facet | Alex Y K Ip Alex Y K Ip Biyun eChing Biyun eChing Kum C. Hiong Kum C. Hiong Yen Ling eChoo Mel Veen Boo WaiP eWong S F Chew |
| author_sort | Alex Y K Ip |
| collection | DOAJ |
| description | 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 NH4+ or H+, and activities of enzymes involved in converting NH4+ 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 NH4+ in substitution for K+ to activate Na+/K+-ATPase (NKA), manifested as a significant increase in the Na+/NH4+-activated-NKA activity in the inner mantle. However, similar phenomena were not observed in the extensible outer mantle, which contained abundant symbiotic zooxanthellae. Hence, during light-enhanced calcification, H+ released from CaCO3 deposition could react with NH3 to form NH4+ in the extrapallial fluid, and NH4+ could probably be transported into the shell-facing inner mantle epithelium through NKA. Light also induced an increase in the activity of glutamine synthetase, which converts NH4+ and glutamate to glutamine, in the inner mantle. Taken together, these results explained observations reported elsewhere that light induced a significant increase in pH and a significant decrease in ammonia concentration in the extrapallial fluid, as well as a significant increase in the glutamine concentration in the inner mantle, of T. squamosa. Exposure of T. squamosa to light also led to a significant decrease in the N-ethylmaleimide (NEM)-sensitive-V-H+-ATPase (VATPase) in the inner mantle, and significant increases in the Na+/K+-activated-NKA, H+/NH4+-activated-H+/K+-ATPase and NEM-sensitive-VATPase activities in ctenidia, indicating that light-enhanced calcification might perturb Na+ homeostasis and acid/base balance in the hemolymph, and might involve the active uptake of NH4+ from the environment. This is the first report on light having direct enhancing effects on activities of certain transporters/enz |
| first_indexed | 2024-04-12T18:20:06Z |
| format | Article |
| id | doaj.art-bd584ae071dd48e0ac5fad45b3309cc1 |
| institution | Directory Open Access Journal |
| issn | 1664-042X |
| language | English |
| last_indexed | 2024-04-12T18:20:06Z |
| publishDate | 2015-03-01 |
| publisher | Frontiers Media S.A. |
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| series | Frontiers in Physiology |
| spelling | doaj.art-bd584ae071dd48e0ac5fad45b3309cc12022-12-22T03:21:28ZengFrontiers Media S.A.Frontiers in Physiology1664-042X2015-03-01610.3389/fphys.2015.00068120517Light induces changes in activities of Na+/K+(NH4+)-ATPase, H+/K+(NH4+)-ATPase and glutamine synthetase in tissues involved directly or indirectly in light-enhanced calcification in the giant clam Tridacna squamosaAlex Y K Ip0Alex Y K Ip1Biyun eChing2Biyun eChing3Kum C. Hiong4Kum C. Hiong5Yen Ling eChoo6Mel Veen Boo7WaiP eWong8S F Chew9Department of Biological Science, National University of SingaporeThe Tropical Marine Science Institute, National University of SingaporeDepartment of Biological Science, National University of SingaporeThe Tropical Marine Science Institute, National University of SingaporeDepartment of Biological Science, National University of SingaporeThe Tropical Marine Science Institute, National University of SingaporeDepartment of Biological Science, National University of SingaporeDepartment of Biological Science, National University of SingaporeDepartment of Biological Science, National University of SingaporeNational Institute of Education, Nanyang Technological UniversityThe 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 NH4+ or H+, and activities of enzymes involved in converting NH4+ 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 NH4+ in substitution for K+ to activate Na+/K+-ATPase (NKA), manifested as a significant increase in the Na+/NH4+-activated-NKA activity in the inner mantle. However, similar phenomena were not observed in the extensible outer mantle, which contained abundant symbiotic zooxanthellae. Hence, during light-enhanced calcification, H+ released from CaCO3 deposition could react with NH3 to form NH4+ in the extrapallial fluid, and NH4+ could probably be transported into the shell-facing inner mantle epithelium through NKA. Light also induced an increase in the activity of glutamine synthetase, which converts NH4+ and glutamate to glutamine, in the inner mantle. Taken together, these results explained observations reported elsewhere that light induced a significant increase in pH and a significant decrease in ammonia concentration in the extrapallial fluid, as well as a significant increase in the glutamine concentration in the inner mantle, of T. squamosa. Exposure of T. squamosa to light also led to a significant decrease in the N-ethylmaleimide (NEM)-sensitive-V-H+-ATPase (VATPase) in the inner mantle, and significant increases in the Na+/K+-activated-NKA, H+/NH4+-activated-H+/K+-ATPase and NEM-sensitive-VATPase activities in ctenidia, indicating that light-enhanced calcification might perturb Na+ homeostasis and acid/base balance in the hemolymph, and might involve the active uptake of NH4+ from the environment. This is the first report on light having direct enhancing effects on activities of certain transporters/enzhttp://journal.frontiersin.org/Journal/10.3389/fphys.2015.00068/fullAmmoniaGlutaminaseGlutamateCa2+-ATPaseH+-ATPasezooxanthellae |
| spellingShingle | Alex Y K Ip Alex Y K Ip Biyun eChing Biyun eChing Kum C. Hiong Kum C. Hiong Yen Ling eChoo Mel Veen Boo WaiP eWong S F Chew Light induces changes in activities of Na+/K+(NH4+)-ATPase, H+/K+(NH4+)-ATPase and glutamine synthetase in tissues involved directly or indirectly in light-enhanced calcification in the giant clam Tridacna squamosa Frontiers in Physiology Ammonia Glutaminase Glutamate Ca2+-ATPase H+-ATPase zooxanthellae |
| title | Light induces changes in activities of Na+/K+(NH4+)-ATPase, H+/K+(NH4+)-ATPase and glutamine synthetase in tissues involved directly or indirectly in light-enhanced calcification in the giant clam Tridacna squamosa |
| title_full | Light induces changes in activities of Na+/K+(NH4+)-ATPase, H+/K+(NH4+)-ATPase and glutamine synthetase in tissues involved directly or indirectly in light-enhanced calcification in the giant clam Tridacna squamosa |
| title_fullStr | Light induces changes in activities of Na+/K+(NH4+)-ATPase, H+/K+(NH4+)-ATPase and glutamine synthetase in tissues involved directly or indirectly in light-enhanced calcification in the giant clam Tridacna squamosa |
| title_full_unstemmed | Light induces changes in activities of Na+/K+(NH4+)-ATPase, H+/K+(NH4+)-ATPase and glutamine synthetase in tissues involved directly or indirectly in light-enhanced calcification in the giant clam Tridacna squamosa |
| title_short | Light induces changes in activities of Na+/K+(NH4+)-ATPase, H+/K+(NH4+)-ATPase and glutamine synthetase in tissues involved directly or indirectly in light-enhanced calcification in the giant clam Tridacna squamosa |
| title_sort | light induces changes in activities of na k nh4 atpase h k nh4 atpase and glutamine synthetase in tissues involved directly or indirectly in light enhanced calcification in the giant clam tridacna squamosa |
| topic | Ammonia Glutaminase Glutamate Ca2+-ATPase H+-ATPase zooxanthellae |
| url | http://journal.frontiersin.org/Journal/10.3389/fphys.2015.00068/full |
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