S F Chew

Summary

Affiliation: Nanyang Technological University
Country: Singapore

Publications

  1. ncbi request reprint Light induces an increase in the pH of and a decrease in the ammonia concentration in the extrapallial fluid of the giant clam Tridacna squamosa
    Yuen K Ip
    Department of Biological Sciences, National University of Singapore, Republic of Singapore
    Physiol Biochem Zool 79:656-64. 2006
  2. ncbi request reprint Nitrogen metabolism in the African lungfish (Protopterus dolloi) aestivating in a mucus cocoon on land
    Shit F Chew
    Natural Sciences, National Institute of Education, Nanyang Technological University, 1 Nanyang Walk, Singapore 637616, Republic of Singapore
    J Exp Biol 207:777-86. 2004
  3. ncbi request reprint Urea synthesis in the African lungfish Protopterus dolloi--hepatic carbamoyl phosphate synthetase III and glutamine synthetase are upregulated by 6 days of aerial exposure
    Shit F Chew
    Natural Sciences, National Institute of Education, Nanyang Technological University, 1 Nanyang Walk, Singapore 637616, Republic of Singapore
    J Exp Biol 206:3615-24. 2003
  4. ncbi request reprint The African lungfish, Protopterus dolloi, detoxifies ammonia to urea during environmental ammonia exposure
    Shit F Chew
    Natural Sciences, National Institute of Education, Nanyang Technological University, 1 Nanyang Walk, Singapore 637616, Republic of Singapore
    Physiol Biochem Zool 78:31-9. 2005
  5. ncbi request reprint Nitrogen metabolism and excretion in the swamp eel, Monopterus albus, during 6 or 40 days of estivation in mud
    S F Chew
    Natural Sciences, National Institute of Education, Nanyang Technological University, 1 Nanyang Walk, Singapore 637616, Republic of Singapore
    Physiol Biochem Zool 78:620-9. 2005
  6. ncbi request reprint Alkaline environmental pH has no effect on ammonia excretion in the mudskipper Periophthalmodon schlosseri but inhibits ammonia excretion in the related species Boleophthalmus boddaerti
    S F Chew
    Natural Sciences, National Institute of Education, Nanyang Technological University, 1 Nanyang Walk, Singapore 637616, Republic of Singapore
    Physiol Biochem Zool 76:204-14. 2003
  7. ncbi request reprint Exposure to brackish water, upon feeding, leads to enhanced conservation of nitrogen and increased urea synthesis and retention in the Asian freshwater stingray Himantura signifer
    Shit F Chew
    Natural Sciences and Science Education, National Institute of Education, Nanyang Technological University, 1 Nanyang Walk, Singapore 637616, Republic of Singapore
    J Exp Biol 209:484-92. 2006
  8. ncbi request reprint The snakehead Channa asiatica accumulates alanine during aerial exposure, but is incapable of sustaining locomotory activities on land through partial amino acid catabolism
    Shit F Chew
    Natural Sciences, National Institute of Education, Nanyang Technological University, 1 Nanyang Walk, Singapore 637616, Republic of Singapore
    J Exp Biol 206:693-704. 2003
  9. ncbi request reprint The loach Misgurnus anguillicaudatus reduces amino acid catabolism and accumulates alanine and glutamine during aerial exposure
    S F Chew
    Natural Sciences Academic Group, Nanyang Technological University, National Institute of Education, 1 Nanyang Walk, Singapore 637616, Republic of Singapore
    Physiol Biochem Zool 74:226-37. 2001
  10. ncbi request reprint Excretory nitrogen metabolism and defence against ammonia toxicity in air-breathing fishes
    S F Chew
    Natural Sciences and Science Education, National Institute of Education, Nanyang Technological University, 1 Nanyang Walk, Singapore 637616, Republic of Singapore
    J Fish Biol 84:603-38. 2014

Collaborators

Detail Information

Publications31

  1. ncbi request reprint Light induces an increase in the pH of and a decrease in the ammonia concentration in the extrapallial fluid of the giant clam Tridacna squamosa
    Yuen K Ip
    Department of Biological Sciences, National University of Singapore, Republic of Singapore
    Physiol Biochem Zool 79:656-64. 2006
    ..squamosa...
  2. ncbi request reprint Nitrogen metabolism in the African lungfish (Protopterus dolloi) aestivating in a mucus cocoon on land
    Shit F Chew
    Natural Sciences, National Institute of Education, Nanyang Technological University, 1 Nanyang Walk, Singapore 637616, Republic of Singapore
    J Exp Biol 207:777-86. 2004
    ..Our results indicate that a reduction in ammonia production and decreases in hepatic arginine and cranial tryptophan contents are important facets of aestivation in P. dolloi...
  3. ncbi request reprint Urea synthesis in the African lungfish Protopterus dolloi--hepatic carbamoyl phosphate synthetase III and glutamine synthetase are upregulated by 6 days of aerial exposure
    Shit F Chew
    Natural Sciences, National Institute of Education, Nanyang Technological University, 1 Nanyang Walk, Singapore 637616, Republic of Singapore
    J Exp Biol 206:3615-24. 2003
    ..dolloi possesses transporters that facilitate the excretion of urea in water...
  4. ncbi request reprint The African lungfish, Protopterus dolloi, detoxifies ammonia to urea during environmental ammonia exposure
    Shit F Chew
    Natural Sciences, National Institute of Education, Nanyang Technological University, 1 Nanyang Walk, Singapore 637616, Republic of Singapore
    Physiol Biochem Zool 78:31-9. 2005
    ..dolloi was adapted to synthesizing and excreting urea for the purpose of ammonia detoxification...
  5. ncbi request reprint Nitrogen metabolism and excretion in the swamp eel, Monopterus albus, during 6 or 40 days of estivation in mud
    S F Chew
    Natural Sciences, National Institute of Education, Nanyang Technological University, 1 Nanyang Walk, Singapore 637616, Republic of Singapore
    Physiol Biochem Zool 78:620-9. 2005
    ..albus. This might explain why M. albus is able to estivate in mud for long periods (40 d) but can survive in air for only <10 d...
  6. ncbi request reprint Alkaline environmental pH has no effect on ammonia excretion in the mudskipper Periophthalmodon schlosseri but inhibits ammonia excretion in the related species Boleophthalmus boddaerti
    S F Chew
    Natural Sciences, National Institute of Education, Nanyang Technological University, 1 Nanyang Walk, Singapore 637616, Republic of Singapore
    Physiol Biochem Zool 76:204-14. 2003
    ..Such a capability, together with modifications in gill morphology and morphometry as in P. schlosseri, might be essential to the development of an effective mechanism for the active excretion of NH+4...
  7. ncbi request reprint Exposure to brackish water, upon feeding, leads to enhanced conservation of nitrogen and increased urea synthesis and retention in the Asian freshwater stingray Himantura signifer
    Shit F Chew
    Natural Sciences and Science Education, National Institute of Education, Nanyang Technological University, 1 Nanyang Walk, Singapore 637616, Republic of Singapore
    J Exp Biol 209:484-92. 2006
    ..Taken together, these results indicate that H. signifer in freshwater could be confronted with postprandial osmotic stress because of its capacity of conserving N and increasing urea synthesis upon feeding...
  8. ncbi request reprint The snakehead Channa asiatica accumulates alanine during aerial exposure, but is incapable of sustaining locomotory activities on land through partial amino acid catabolism
    Shit F Chew
    Natural Sciences, National Institute of Education, Nanyang Technological University, 1 Nanyang Walk, Singapore 637616, Republic of Singapore
    J Exp Biol 206:693-704. 2003
    ....
  9. ncbi request reprint The loach Misgurnus anguillicaudatus reduces amino acid catabolism and accumulates alanine and glutamine during aerial exposure
    S F Chew
    Natural Sciences Academic Group, Nanyang Technological University, National Institute of Education, 1 Nanyang Walk, Singapore 637616, Republic of Singapore
    Physiol Biochem Zool 74:226-37. 2001
    ..anguillicaudatus uses partial amino acid catabolism to fuel its short period of activities on land and switches to the formation of glutamine to detoxify internally produced ammonia when it remains relatively inactive in the mud...
  10. ncbi request reprint Excretory nitrogen metabolism and defence against ammonia toxicity in air-breathing fishes
    S F Chew
    Natural Sciences and Science Education, National Institute of Education, Nanyang Technological University, 1 Nanyang Walk, Singapore 637616, Republic of Singapore
    J Fish Biol 84:603-38. 2014
    ..In summary, the responses of air-breathing fishes to ameliorate ammonia toxicity are many and varied, determined by the behaviour of the species and the nature of the environment in which it lives...
  11. ncbi request reprint Cyanide exposure affects the production and excretion of ammonia by the mudskipper Boleophthalmus boddaerti
    S F Chew
    Biology Division, School of Science, National Institute of Education, Nanyang Technological University, Singapore, Singapore
    Comp Biochem Physiol C Pharmacol Toxicol Endocrinol 120:441-8. 1998
    ..boddaerti during the early phase of cyanide exposure...
  12. ncbi request reprint The giant mudskipper Periophthalmodon schlosseri facilitates active NH(4)(+) excretion by increasing acid excretion and decreasing NH(3) permeability in the skin
    Yuen K Ip
    Department of Biological Sciences, National University of Singapore, 10 Kent Ridge Road, Singapore 117543, Republic of Singapore
    J Exp Biol 207:787-801. 2004
    ..0) for 6 days. These changes might lead to an even lower permeability to NH(3) in the skin, and reduced back diffusion of the actively excreted NH(4)(+) as NH(3) or the net influx of exogenous NH(3), under such conditions...
  13. ncbi request reprint Greatly elevated urea excretion after air exposure appears to be carrier mediated in the slender lungfish (Protopterus dolloi)
    Chris M Wood
    Department of Biology, McMaster University, Hamilton, Ontario L8S 4K1, Canada
    Physiol Biochem Zool 78:893-907. 2005
    ....
  14. ncbi request reprint Excretory nitrogen metabolism in the juvenile axolotl Ambystoma mexicanum: differences in aquatic and terrestrial environments
    Ai M Loong
    Department of Biological Science, National University of Singapore, Kent Ridge, Singapore 117543, Republic of Singapore
    Physiol Biochem Zool 75:459-68. 2002
    ..Hence, it can be concluded that the juvenile axolotl acquired ureotelism while submerged in water, and its hepatic capacity of urea synthesis was more than adequate to handle the toxicity of endogenous ammonia during migration to land...
  15. ncbi request reprint Postprandial increases in nitrogenous excretion and urea synthesis in the Chinese soft-shelled turtle, Pelodiscus sinensis
    Serene M L Lee
    Department of Biological Science, National University of Singapore, Kent Ridge, Singapore 117543, Republic of Singapore
    J Comp Physiol B 177:19-29. 2007
    ..sinensis. After feeding, a slight but significant increase in the glutamine content occurred in the brain at hour 24, indicating that the brain might experience a transient increase in ammonia and ammonia was detoxified to glutamine...
  16. ncbi request reprint Active ammonia transport and excretory nitrogen metabolism in the climbing perch, Anabas testudineus, during 4 days of emersion or 10 minutes of forced exercise on land
    Yi L Tay
    Department of Biological Science, National University of Singapore, Kent Ridge, Singapore 117543, Republic of Singapore
    J Exp Biol 209:4475-89. 2006
    ..testudineus as an energy source to support locomotor activity during emersion. As a result, it is capable of wandering long distance on land from one water body to another as reported in the literature...
  17. ncbi request reprint Ammonia toxicity and tolerance in the brain of the African sharptooth catfish, Clarias gariepinus
    Nicklaus L J Wee
    Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore 117543, Republic of Singapore
    Aquat Toxicol 82:204-13. 2007
    ..Instead, MSO affected activities of glutamate dehydrogenase and alanine aminotransferase and suppressed the rate of ammonia build up in the brain of fish injected with a lethal dose of CH(3)COONH(4)...
  18. ncbi request reprint Active ammonia excretion in the giant mudskipper, Periophthalmodon schlosseri (Pallas), during emersion
    Shit F Chew
    Natural Sciences and Science Education, National Institute of Education, Nanyang Technological University, Singapore, Republic of Singapore
    J Exp Zool A Ecol Genet Physiol 307:357-69. 2007
    ..Only 4.6% of the exogenous ammonia was detoxified to urea. The glutamate contents in the muscle and liver also increased significantly, but the glutamine contents remained unchanged...
  19. ncbi request reprint Increased urea synthesis and/or suppressed ammonia production in the African lungfish, Protopterus annectens, during aestivation in air or mud
    Ai M Loong
    Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore, 117543, Republic of Singapore
    J Comp Physiol B 178:351-63. 2008
    ..Consequently, fish aestivating in mud had a lower dependency on increased urea synthesis to detoxify ammonia, which is energy intensive, than fish aestivating in air...
  20. ncbi request reprint The swamp eel Monopterus albus reduces endogenous ammonia production and detoxifies ammonia to glutamine during 144 h of aerial exposure
    Angeline S L Tay
    Department of Biological Science, National University of Singapore, Kent Ridge, Singapore 117543, Republic of Singapore
    J Exp Biol 206:2473-86. 2003
    ..albus in the mud for longer periods during drought because ammonia and glutamine concentrations had already built up to high levels in the body of specimens exposed to air for 144 h...
  21. ncbi request reprint Marine (Taeniura lymma) and freshwater (Himantura signifer) elasmobranchs synthesize urea for osmotic water retention
    Yuen K Ip
    Department of Biological Science, National University of Singapore, Kent Ridge, Singapore 117543, Republic of Singapore
    Physiol Biochem Zool 78:610-9. 2005
    ..signifer. Taken together, these results suggest that the primary function of the ornithine-urea cycle in ureogenic marine and freshwater elasmobranchs is to synthesize urea for osmotic water retention and not for ammonia detoxification...
  22. ncbi request reprint Changes in salinity and ionic compositions can act as environmental signals to induce a reduction in ammonia production in the African lungfish Protopterus dolloi
    Yuen K Ip
    Department of Biological Sciences, National University of Singapore, Singapore 117543, Republic of Singapore
    J Exp Zool A Comp Exp Biol 303:456-63. 2005
    ..In conclusion, our results suggest that P. dolloi could respond to increases in salinity and changes in ionic composition in the external medium by suppressing ammonia production in preparation for aestivation when the water dries up...
  23. ncbi request reprint African sharptooth catfish Clarias gariepinus does not detoxify ammonia to urea or amino acids but actively excretes ammonia during exposure to environmental ammonia
    Yuen K Ip
    Department of Biological Sciences, National University of Singapore, 10 Kent Ridge Road, Singapore 117543, Republic of Singapore
    Physiol Biochem Zool 77:242-54. 2004
    ..These results represent the first report on a freshwater fish (C. gariepinus) adopting active excretion of ammonia (probably NH4+) as a major strategy to defend against ammonia toxicity when exposed to environmental ammonia...
  24. ncbi request reprint Postprandial increases in nitrogenous excretion and urea synthesis in the giant mudskipper Periophthalmodon schlosseri
    Yuen K Ip
    Department of Biological Science, National University of Singapore, Kent Ridge, Singapore 117543, Republic of Singapore
    J Exp Biol 207:3015-23. 2004
    ..schlosseri throughout the 24 h period post-feeding, accompanied by a significant decrease in brain glutamine content between 12 h and 24 h...
  25. ncbi request reprint Strategies for surviving high concentrations of environmental ammonia in the swamp eel Monopterus albus
    Yuen K Ip
    Department of Biological Science, National University of Singapore, Kent Ridge, Singapore 117543, Republic of Singapore
    Physiol Biochem Zool 77:390-405. 2004
    ..albus was suppressed in order to prevent the newly established internal steady state concentration of ammonia from rising to an intolerable level after an extended period of exposure to HEA...
  26. ncbi request reprint Strategies adopted by the mudskipper Boleophthalmus boddaerti to survive sulfide exposure in normoxia or hypoxia
    Yuen K Ip
    Department of Biological Sciences, National University of Singapore, 10 Kent Ridge Road, Singapore 117543, Republic of Singapore
    Physiol Biochem Zool 77:824-37. 2004
    ..boddaerti detoxified sulfide mainly to sulfane sulfur in hypoxia. In conclusion, B. boddaerti was able to activate different mechanisms to detoxify sulfide, producing different types of detoxification products in normoxia and hypoxia...
  27. ncbi request reprint A comparison of the effects of environmental ammonia exposure on the Asian freshwater stingray Himantura signifer and the Amazonian freshwater stingray Potamotrygon motoro
    Yuen K Ip
    Department of Biological Science, National University of Singapore, Kent Ridge, Singapore 117543, Republic of Singapore
    J Exp Biol 206:3625-33. 2003
    ..Our results suggest that such a strategy began to develop in those elasmobranchs, e.g. H. signifer, that migrate into a freshwater environment from the sea but not in those permanently adapted to a freshwater environment...
  28. ncbi request reprint The osmotic response of the Asian freshwater stingray (Himantura signifer) to increased salinity: a comparison with marine (Taeniura lymma) and Amazonian freshwater (Potamotrygon motoro) stingrays
    Wai L Tam
    Department of Biological Science, National University of Singapore, Kent Ridge, Singapore 117543, Republic of Singapore
    J Exp Biol 206:2931-40. 2003
    ..signifier in 20 per thousand water. Therefore, H. signifer appears to have reduced its capacity to retain urea in order to survive in the freshwater environment and, consequently, it could not survive well in full-strength seawater...
  29. ncbi request reprint Effects of intra-peritoneal injection with NH4Cl, urea, or NH4Cl+urea on nitrogen excretion and metabolism in the African lungfish Protopterus dolloi
    Yuen K Ip
    Department of Biological Sciences, National University of Singapore, 10 Kent Ridge Road, Singapore 117543, Republic of Singapore
    J Exp Zool A Comp Exp Biol 303:272-82. 2005
    ..These results suggest that urea excretion in P. dolloi is likely to be regulated by the level of internal ammonia in its body...
  30. ncbi request reprint Chronic and acute ammonia toxicity in mudskippers, Periophthalmodon schlosseri and Boleophthalmus boddaerti: brain ammonia and glutamine contents, and effects of methionine sulfoximine and MK801
    Yuen K Ip
    Department of Biological Science, National University of Singapore, Kent Ridge, Singapore 117543, Republic of Singapore
    J Exp Biol 208:1993-2004. 2005
    ..Thus, it can be concluded that there are major differences in mechanisms of chronic and acute ammonia toxicity between brains of these two mudskippers and mammalian brains...
  31. ncbi request reprint Exposure to air, but not seawater, increases the glutamine content and the glutamine synthetase activity in the marsh clam Polymesoda expansa
    Kum C Hiong
    Department of Biological Sciences, National University of Singapore, 10 Kent Ridge Road, Singapore 117543, Republic of Singapore
    J Exp Biol 207:4605-14. 2004
    ....