Ionocyte

Microscopic image of two ionocytes in a gill

An ionocyte (formerly called a chloride cell) is a mitochondrion-rich cell within ionoregulatory organs of animals, such as teleost fish gill, insect Malpighian tubules, crustacean gills, antennal glands and maxillary glands, and copepod Crusalis organs.[1] These cells contribute to the maintenance of optimal osmotic, ionic, and acid-base levels within metazoans. In aquatic invertebrates, ionocytes perform the functions of both ion uptake and ion excretion.[2] In marine teleost fish, by expending energy to power the enzyme Na+/K+-ATPase and in coordination with other protein transporters, ionocytes pump excessive sodium and chloride ions against the concentration gradient into the ocean.[3][4][5] Conversely, freshwater teleost ionocytes use this low intracellular environment to attain sodium and chloride ions into the organism, and also against the concentration gradient.[3][5] In larval fishes with underdeveloped / developing gills, ionocytes can be found on the skin and fins.[6][7][8]

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  4. ^ Marshall WS (August 2002). "Na(+), Cl(-), Ca(2+) and Zn(2+) transport by fish gills: retrospective review and prospective synthesis". The Journal of Experimental Zoology. 293 (3): 264–83. doi:10.1002/jez.10127. PMID 12115901.
  5. ^ a b Hirose S, Kaneko T, Naito N, Takei Y (December 2003). "Molecular biology of major components of chloride cells". Comparative Biochemistry and Physiology. Part B, Biochemistry & Molecular Biology. 136 (4): 593–620. doi:10.1016/s1096-4959(03)00287-2. PMID 14662288.
  6. ^ Glover CN, Bucking C, Wood CM (October 2013). "The skin of fish as a transport epithelium: a review". Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology. 183 (7): 877–91. doi:10.1007/s00360-013-0761-4. PMID 23660826. S2CID 17089043.
  7. ^ Kwan GT, Wexler JB, Wegner NC, Tresguerres M (February 2019). "Ontogenetic changes in cutaneous and branchial ionocytes and morphology in yellowfin tuna (Thunnus albacares) larvae". Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology. 189 (1): 81–95. doi:10.1007/s00360-018-1187-9. PMID 30357584. S2CID 53025702.
  8. ^ Varsamos S, Nebel C, Charmantier G (August 2005). "Ontogeny of osmoregulation in postembryonic fish: a review". Comparative Biochemistry and Physiology. Part A, Molecular & Integrative Physiology. 141 (4): 401–29. doi:10.1016/j.cbpb.2005.01.013. PMID 16140237.