滲透壓與離子的調節與恆定是海洋脊椎動物面臨的生存挑戰之一，而個體的滲透壓調節能力往往與其海棲程度有相關性。海蛇的後端舌下腺(posterior sublingual gland)為其鹽腺，能夠排出濃縮的氯化鈉以維持滲透壓的恆定。鹽腺管狀構造之上皮由主細胞(principal cell)構成。主細胞底側膜上Na+/K+ -ATPase (NKA)以耗能的主動運輸將體內過多的鹽分排除體外。三種不同海棲程度的闊尾海蛇(Laticauda spp.)分布於台灣的蘭嶼及綠島；闊帶青斑海蛇(L. semifasciata)是海棲程度最高的物種，黑唇青斑海蛇(L. laticaudata)次之，而黃唇青斑海(L. colubrina)蛇是最陸棲的物種。本實驗目的為比較台灣三種闊尾海蛇的滲透壓調節力是否有所差異並呼應其海棲程度。將三種闊尾海蛇分別從陸域轉移至海水及淡水馴養，分析轉移後的第0, 2, 7, 14天的血漿滲透壓、血漿離子濃度、血球容積比、肌肉含水量以及鹽腺和腎臟的NKA活性變化，用這些指標來分析其滲透壓調節能力。結果顯示，相較於黑唇及黃唇青斑海蛇，海棲程度最高的闊帶青斑海蛇維持體液滲透壓、鈉氯離子濃度以及肌肉含水量最為穩定。闊帶青斑海蛇及黑唇青斑海蛇的鹽腺NKA活性在海水馴養組皆顯著高於淡水馴養組，而陸棲程度最高的黃唇青斑海蛇的鹽腺NKA活性不論轉移至海水或淡水都沒有顯著變化。以上證據顯示闊帶青斑海蛇的滲透壓調節能力較黑唇青斑海蛇及黃唇青斑海蛇佳。而最陸棲的黃唇青斑海蛇似乎採取不同於闊帶與黑唇青斑海蛇的滲透壓調節策略因應環境鹽度變化。

Marine invasions have occurred multiple times independently among vertebrates. To permit the successful habitation of marine environments, the specialized ionoregulatory tissues have evolved, likely been responsible for ameliorating ionic challenge. Therefore, salt gland has evolved multiple times throughout the evolution of marine vertebrates. The sublingual salt gland is the primary organ of salt excretion in sea snakes, and Na+/K+–ATPase (NKA) in the basolateral membrane provides the driving force for salt secretion. In this study, the osmoregulatory capability of three sea kraits (Laticauda spp.) in Taiwan were examined and compared to test if their osmoregulatory capability is associated with their different habitats affinity from terrestrial to marine. The sea kraits were transferred from terrestrial environment to freshwater (FW) or seawater (SW) for 0, 2, 7, and 14 days. At various time points, their salt glands and kidneys were sampled for NKA activity analysis; muscles were sampled for water content measurement; blood were sampled for the analysis of hematocrit, osmolality, and ionic concentrations. Results showed that the most marine species, L. semifasciata maintained better constancy in plasma osmolality, Na+, Cl- levels and water content. In L. semifasciata and L. laticaudata, the NKA activity of the salt gland was higher in SW than in FW. However, in the most terrestrial species, L. colubrina, no significant difference of NKA activity was found between SW and FW groups. These results suggest that the capability of osmoregulation is better in L. semifasciata than in the other two species, and L. colubrina may have different osmoregulatory strategy with the other two species.

Anderson, W. G., Taylor, J. R., Good, J. P., Hazon, N. and Grosell, M. (2007). Body fluid volume regulation in elasmobranch fish. Comp. Biochem. Physiol. 148A, 3-13.
Babonis, L. S., Hyndman, K. A., Lillywhite, H. B. and Evans, D. H. (2009). mmunolocalization of Na+/K+–ATPase and Na+/K+/2Cl- cotransporter in the tubular epithelia of sea snake salt glands. Comp. Biochem. Physiol. 154A, 535-540.
Bennett, D. C. and Hughes, M. R. (2003). Comparison of renal and salt gland function in three species of wild ducks. J. Exp. Biol. 206, 3273-3284.
Benyajati, S., Yokota, S. D. and Dantzler, W. H. (1985). Renal function in sea snakes. II. Sodium, potassium, and magnesium excretion. Am. J. Physiol. 249, R237–R245.
Bonnet, X. and Brischoux, F. (2008). Thirsty sea snakes forsake refuge during rainfall. Aust. Ecol. 33, 911-921.
Burger, J. W. (1965). Roles of the rectal gland and kidneys in salt and water excretion in the spiny dogfish. Physiol. Zool. 38, 191–196.
Chan, D. K., and Phillips, J. G. (1967). The anatomy, histology and histochemistry of the rectal gland in the lip-shark Hemiscyllium plagiosum (Bennett). J. Anat. 101, 137-157.
Chew, S. F., Tng, Y. Y. M., Wee, N. L. J., Wilson, J. M. and Ip, Y. K. (2009). Nitrogen metabolism and branchial osmoregulatory acclimation in the juvenile marble goby, Oxyeleotris marmorata, exposed to seawater. Comp. Biochem. Physiol. 154A, 360–369.
Cogger, H. and Heatwole, H. (2006). Laticauda frontalis (de Vis, 1905) and Laticauda saintgironsi n. sp. from Vanuatu and New Caledonia (Serpentes: Elapidae: Laticaudinae)-a new lineage of sea kraits? Rec. Aust. Mus. 58, 245-256.
Cramp, R. L., Hudson, N. J. and Franklin, C. E. (2010). Activity, abundance, distribution and expression of Na+/K+-ATPase in the salt glands of Crocodylus porosus following chronic saltwater acclimation. J. Exp. Biol. 213, 1301-1308.
Cramp, R. L., Meyer, E. A., Sparks, N. and Franklin, C. E. (2008). Functional and morphological plasticity of crocodile (Crocodylus porosus) salt glands. J. Exp. Biol. 211, 1482-1489.
Dunson, W .A. (1969). Electrolyte excretion by the salt gland of the Galapagos marine iguana. Am. J. Physiol. 216, 995-1002.
Dunson, W. A. (1970). Some aspects of electrolyte and water balance in three estuarine reptiles, the diamondback terrapin, American and “salt water” crocodiles. Comp. Biochem. Physiol.32, 161-174.
Dunson, W. A. (1978). Role of the skin in sodium and water exchange of aquatic snakes placed in seawater. Am. J. Physiol. 235, 151–159.
Dunson, M. K. and Dunson, W. A. (1975). The relation between plasma Na concentration and salt gland Na- K ATPase content in the diamondback terrapin and the yellow-bellied sea snake. J. Comp. Physiol. 101, 89-97.
Dunson, W. A., and Dunson, M. K. (1973). Convergent evolution of sublingual salt glands in the marine file snake and the true sea snakes. J. Comp. Physiol. 86, 193-208.
Dunson, W. A., and Dunson, M. K. (1974). Interspecific differences in fluid concentration and secretion rate of sea snake salt glands. Am. J. Physiol. 227, 430–438.
Dunson, W. A. and Dunson, M. K. (1979). A possible new salt gland in marine homalopsid snake (Cerberus rhynchops). Copeia 1979, 661-672.
Dunson, W. A. and Mazzotti, F. J. (1989). Salinity as a limiting factor in the distribution of reptiles in Florida Bay: a theory for the estuarine origin of marine snakes and turtles. Bull. Mar. Sci. 44, 229-244.
Dunson, W. A., Packer, R. K. and Dunson, M. K. (1971). Sea snakes: an unusual salt gland under the tongue. Science 173, 437-441.
Dunson, W. A. and Robinson, G. D. (1976). Sea snake skin: permeable to water but not to sodium. J. Comp. Physiol. 108B, 303-311.
Ernst, S. A., Crawford, K. M., Post, M. A. and Cohn, J.A. (1994). Salt stress increases abundance and glycosylation of CFTR localized at apical surfaces of salt gland secretory cells. Am. J. Physiol. 267, C990–C1001.
Evans, D, H., Piermarini, P. M. and Choe, K. P. (2005). The multifunctional fish gill: dominant site of gas exchange, osmoregulation, acid-base regulation, and excretion of nitrogenous waste. Physiol. Rev. 85, 97-177.
Evans, D. H. (2009 a). Osmotic and ionic regulation in fishes. In Osmotic and Ionic Regulation: Cells and Animals (ed D. H. Evans and J. B. Claiborne), pp. 295-366. Boca Raton, FL: CRC Press.
Evans, D. H. (2009 b). Osmotic and ionic regulation in Reptiles. In Osmotic and Ionic Regulation: Cells and Animals (ed W. A. Dantzler and S. D. Bradshaw), pp. 443-504. Boca Raton, FL: CRC Press.
Evans, D. H. (2009 c). Osmotic and ionic regulation in birds. In Osmotic and Ionic Regulation: Cells and Animals (ed E. J. Braun), pp. 505-524. Boca Raton, FL: CRC Press.
Franklin, C. E., Taylor, G. and Cramp, R. L. (2005). Cholinergic and adrenergic innervation of lingual salt glands of the estuarine crocodile, Crocodylus porosus. Auts. J. Zool. 53, 345-351.
Freire, C. A., Amado, E. M., Souza, L. R., Veiga, M., Vitule, J. R. S., Souza, M. M. and Prodocimo, V. (2008). Muscle water control in crustaceans and fishes as a function of habitat, osmoregulatory capacity, and degree of euryhalinity. Comp. Biochem. Physiol. 149A, 435–445.
Grigg, G. C. (1981). Plasma homeostasis and cloacal urine composition in Crocodylus porosus caught along a salinity gradient. J. Comp. Physiol. 144B, 261-270.
Hammerschlag, N. (2006). Osmoregulation in elasmobranchs: a review for fish biologists, behaviourists and ecologists. Mar. Fresh. Behav. Physiol. 39, 209-228.
Heatwole, H. (1999).What are sea snakes. In Sea Snakes, pp. 5-12. Malabar, FL: Krieger Publishing Company.
Hildebrandt, J. P. (2001). Coping with excess salt: adaptive functions of extrarenal osmoregulatory organs in vertebrates. Zoology 104, 209-220.
Hiroi, J. and McCormick S. D. (2007). Variation in salinity tolerance, gill Na+/K+-ATPase, Na+/K+/2Cl– cotransporter and mitochondria-rich cell distribution in three salmonids Salvelinus namaycush, Salvelinus fontinalis and Salmo salar. J. Exp. Biol. 210, 1015-1024.
Hwang, P. P. and Lee, T. H. (2007). New insights into fish ion regulation and mitochondrion-rich cells. Comp. Biochem. Physiol. 148A, 479-497.
Huang, C. Y., Chao, P. L. and Lin, H. C. (2010). Na+/K+-ATPase and vacuolar-type H+-ATPase in the gills of the aquatic air-breathing fish Trichogaster microlepis in response to salinity variation. Comp. Biochem. Physiol. 155A, 309-318.
Hudson, D, M. and Lutz, P. L. (1986). Salt gland function in the leatherback sea turtle, Dermochelys coriacea. Copeia 1986, 247-249.
Hughes, H. R. (2003). Regulation of salt gland, gut and kidney interactions. Comp. Biochem. Physiol. 136A, 507-524.
Jensen, M. K., Madsen, S. S. and Kristiansen, K. (1998). Osmoregulation and salinity effects on the expression and activity of Na+, K+-ATPase in the gills of European sea bass, Dicentrarchus labrax (L.). J. Exp. Zool. 282, 290-300.
Kelly, S. P., Chow, I. N. K. and Woo, N. Y. S. (1999). Halopalasticity of black seabream (Mylio macrocephalus): hypersaline to freshwater acclimation. J. Exp. Zool. 283, 226–241
Kelly, S. P. and Woo, N. Y. S. (1999). The response of sea bream following abrupt hyposmotic exposure. J. Fish. Biol. 55, 732-750.
Kent, B. and Olsen, K. R. (1982). Blood flow in the rectal gland of Squalus acanthias. Am. J. Physiol. 243, R296–R303.
Keogh, J. (1998). Molecular phylogeny of elapid snakes and a consideration of their biogeographic history. Biol. J. Linn. Soc. 63, 177-203.
Kirschner, L.B. (1980). Comparison of vertebrate salt-excreting organs. Am. J. Physiol. 238, R219–R223.
Kuchel, L. J. and Franklin, C. E. (1998). Kidney and cloaca function in the estuarine crocodile (Crocodylus porosus) at different salinities: evidence for solute-linked water uptake. Comp. Biochem. Physiol. 119A, 825-831.
Lillywhite, H. B. (2007). Water and permeability relations of skin: a comparative perspective. Kosmetische Medizin 5, 220-227.
Lillywhite, H. B., Babonis, L. S. and Tu, M. C. (2008). Sea snakes (Laticauda spp.) require fresh drinking water: implication for the distribution and persistence of populations. Physiol. Bichem, Zool. 81, 785-796.
Lillywhite, H. B. and Ellis, T. M. (1994). Ecophysiological aspects of the coastal-estuarine distribution of acrochordid snakes. Estuaries 17, 53-61.
Lillywhite, H. B., Menon, J. G., Menon, G. K., Sheehy 3rd, C. M. and Tu, M. C. (2009). Water exchange and permeability properties of the skin in three species of amphibious sea snakes (Laticauda spp.) J. Exp. Biol. 212, 1921-1929.
Lin, Y. M., Chen, C. N., Yoshinaga, T., Tsai, S. C., Shen, I. D. and Lee, T. H. (2006). Short-term effects of hyposmotic shock on Na+/K+-ATPase expression in gills of the euryhaline milkfish, Chanos chanos. Comp. Biochem. Physiol. 143A, 406-415.
Lin, C. H., Huang, C. L., Yang, C. H., Lee, T. H. and Hwang, P. P. (2004 a). Time-course changes in the expression of Na, K-ATPase and the morphometry of mitochondrion-rich cells in gills of euryhaline tilapia (Oreochromis mossambicus) during freshwater acclimation. J. Exp. Zool.301A, 85–96.
Lin, C. H., Tsai, R. S. and Lee, T. H. (2004 b). Expression and distribution of Na+, K+-ATPase in gill and kidney of the spotted green pufferfish, Tetraodon nigroviridis, in response to salinity challenge. Comp. Biochem. Physiol. 138A, 287-295.
Lowy, R. J., Dawson, D. C. and Ernst, S.A. (1989). Mechanism of ion transport by avian salt gland primary cell cultures. Am. J. Physiol. 256, R1184–R1191.
Madsen, S. S., McCormick, S. D., Young, G. and Endersen, J. S. (1994). Physiology of seawater acclimation in the striped bass, Morone Saxatilis (Walbaum). Fish. Physiol. Biochem. 13, 1 –11.
Marshall, W. S. (2002). Na+, Cl-, Ca2+ and Zn2+ transport by fish gills: retrospective review and prospective synthesis. J. Exp. Zool. 293, 264-283.
Peaker, M. (1971). Avian salt glands. Phil. Trans. Roy. Soc. Lond. 262B, 289-300.
Perry, S. F., Shahsavarani, A., Georgalis, T., Bayaa, M., Furimsky, M. and Thomas, S. L. Y. (2003). Channels, pumps, and exchangers in the gill and kidney of freshwater fishes: their role in ionic and acid–base regulation. J. Exp. Zool. 300A, 53–62.
Piermarini, P. M. and Evans, D. H. (2000). Effects of environmental salinity on Na+/K+-ATPase in the gills and rectal gland of a euryhaline elasmobranch (Dasyatis sabina). J. Exp. Biol. 203, 2957–2966.
Pillans, R. D., Good, J. P., Anderson, W. G., Hazon, N. and Franklin, C. E. (2005). Freshwater to seawater acclimation of juvenile bull sharks (Carcharhinus leucas): plasma osmolytes and Na+/K+-ATPase activity in gill, rectal gland, kidney and intestine. J. Comp. Physiol. 175B, 37-44.
Randall, D., Burggren, W. and French, K. (2002). Ionic and osmotic balance. In Eckert animal physiology, pp. 579-630. New York, NY: W. H. Freeman and company.
Reina, R. D. and Cooper, P. D. (2000). Control of salt gland activity in the hatchling green sea turtle, Chelonia mydas. J. Comp. Physiol. 170B, 27-35.
Reina, R. D., Jones, T. T. and Spotila, J. R. (2002). Salt and water regulation by the leatherback sea turtle Dermochelys coriacea. J. Exp. Biol. 205, 1853-1860.
Rigal, F., Chevalier, T., Lorin-Nebel, C.. Charmantier, G., Tomasini, J. A., Aujoulat, F. and Berrebi, P. (2008). Osmoregulation as a potential factor for the differential distribution of two cryptic gobiid species, Pomatoschistus microps and P. marmoratus in French Mediterranean lagoons. Sci. Mar. 72, 469-476.
Riordan, J. R., Forbush, B. and Hanrahan, J. W. (1994). The molecular basis of chloride transport in shark rectal gland. J. Exp.Biol. 196, 405–418.
Schmidt-Nielsen, K. (1958). Salt gland in marine reptile. Nature 182, 782-785.
Schmidt-Nielsen, K. 1960. The salt-secreting gland of marine birds. Circulation 21, 955–967.
Scott, G. R., Schulte, P. M. and Wood, C. M. (2006). Plasticity of osmoregulatory function in the killifish intestine: drinking rates, salt and water transport, and gene expression after freshwater transfer. J. Exp. Biol. 209, 4040-4050.
Shetty, S. and Shine, R. (2002). Philopatry and homing behavior of sea Snakes (Laticauda colubrina) from two adjacent islands in Fiji. Conserv. Biol. 16, 1422-1426.
Shuttleworth, T. J. and Hildebrandt, J. P. (1999). Vertebrate salt glands: short- and long-term regulation of function. J. Exp. Zool. 283, 689-701.
Silva, P., Solomon, R. J. and Epstein, F. H. (1997). Transport mechanisms that mediate the secretion of chloride by the rectal gland of Squalus acanthias. J. Exp. Zool. 279, 504–508.
Tasi, J. R. and Lin, H. C. (2007) V-type H+-ATPase and Na+,K+-ATPase in the gills of 13 euryhaline crabs during salinity acclimation. J. Exp. Biol.210, 620-627.
Taplin, L. E. (1984). Drinking of fresh water but not seawater by the estuarine crocodile (Crocodylus porosus). Comp. Biochem. Physiol. 77A, 763-767.
Taplin, L. E. and Grigg, G .C. (1981). Salt glands in the tongue of the Estuarine Crocodile Crocodylus porosus. Science 212, 1045-1047.
Taplin, L. E., Grigg, G. C., Harlow, P. Ellis, T .M and Dunson, W. A. (1982). Lingual salt glands in Crocodylus acutus and C. johnstoni and their absence from Alligator mississippiensis and Caiman crocodiles. J. Comp. Physiol.149B, 43-47.
Tipsmark, C. K., Madsen, S. S., Seidelin, M., Christensen, A. S., Cutler, C. P. and Cramb, G. (2002). Dynamics of Na+, K+, 2Cl-cotransporter and Na+, K+-ATPase expression in the branchial epithelium of brown trout (Salmo trutta) and Atlantic salmon (Salmo salar). J. Exp. Zool. 293A, 106–118.
Tu, M. C. (2004). Snakes of Taiwan. In Amazing Snake, pp. 243-245. Taipei: Yuan-Liu Publishing.
Venturini, G., Cataldi, E., Marino, G., Pucci, P., Garibaldi, L. and Bronzi, P. (1992). Serum ions concentration and ATPase activity in gills, kidney and oesophagus of European sea bass (Dicentrarchus labrax, Pisces, Perciformes) during acclimation trials to fresh water. Comp. Biochem. Physiol. 103A, 451– 454
Vermeij, G. J. and Dudley, R. (2000). Why are there so few evolutionary transitions between aquatic and terrestrial ecosysytems ? Biol. J. Linn. Soc. 70, 541-554.
Vitt, L. J. and Caldwell, J. P. (2009). Water balance and gas exchange. In Herpetology, pp. 169-190. Burlington, MA: Academic Press Publications.
Yokota, S. D., Benyajati, S. and Dantzler, W. H. (1985). Renal function in sea snakes. I. Glomerular filtration rate and water handling. Am. J. Physiol. 249, R228–R236.
Willmer, P., Stone, G., and Johnson, I. (2004). Marine life. In Environmental Physiology of Animals, pp. 393-443. Malden, MA: Blackwell Publishing.
Wilson, J. M., Leitao, A., Goncalves, A. F., Ferreira, C., Reis-Santos, P., Fonseca, A. V., da Silva, J. M., Antunes, J. C., Pereira-Wilson, C. and Coimbra, J. (2007). Modulation of branchial ion transport protein expression by salinity in glass eels (Anguilla anguilla L.). Mar. Biol. 151, 1633-1645.
Woo, N. Y. S.and Chung, K. C. (1995). Tolerance of Pomacanthus imperator to hypoosmotic salinities: changes in body composition and hepatic enzyme activities. J. Fish Biol. 47, 70–81.