|Evidence for the presence of ion pumps in the photophores of 2 mesopelagic fishes Argyropelecus and Maurolicus|
Thinessempoux, D.; Baguet, F.; Frankart, C. (1987). Evidence for the presence of ion pumps in the photophores of 2 mesopelagic fishes Argyropelecus and Maurolicus. Comp. Biochem. Physiol., Part A Physiol. 88(1): 75-81
In: Comparative Biochemistry and Physiology. Part A. Physiology. Pergamon: Oxford, U.K.. ISSN 1096-4940, more
|Authors|| || Top |
- Thinessempoux, D.
- Baguet, F., more
- Frankart, C.
1. Adenosine triphosphatase (ATPase) activity has been measured on homogenates of photophores from two mesopelagic fishes Argyropelecus and Maurolicus. This activity is equivalent for both fishes when reported to the protein content as is their O2 consumption.2. The activity is optimal at pH 6.8-7.5. It is not specific for ATP since GTP, ITP, UTP and CTP are also hydrolyzed to a significant extent. It is also not specific for Mg2+, the activity being equivalent (Argyropelecus) or higher (Maurolicus) with Ca2+ and high also with Co2+ and Mn2+.3. Twenty to 30 per cent of the activity measured at pH 7.4 is probably due to the mitochondrial ATPase as it is shown by oligomycin and venturicidin inhibition.4. Activities of both fishes photophores are partly inhibited by N-N’-dicyclohexylcarbodiimide (DCCD), azide, LaCl3, vanadate, diethylstilbestrol (DES) and N-ethylmaleimide (NEM) which are all inhibitors of ionic pumps.5. Argyropelecus activity is sensitive to ouabaïn.6. Our results show the presence of ionic pumps in Argyropelecus and Maurolicus photophores. If there is evidence for the absence or very low activity of a H+ pump, it is sure that Argyropelecus at least possess a Na+K+-ATPase.7. The significance of a high protein content in Maurolicus photophores and of a large inorganic phosphate concentration in Argyropelecus is discussed.