Localization and diurnal variations of carbonic anhydrase mRNA expression in the inner ear of the rainbow trout Oncorhynchus mykiss
- Tohse, H., Murayama, E., Ohira, T., Takagi, Y., and Nagasawa, H.
- Comparative biochemistry and physiology. Part B, Biochemistry & molecular biology 145(3-4): 257-264 (Journal)
- Registered Authors
- Murayama, Emi
- Biomineralization, Carbonic anhydrase, Endolymph, Otolith, Rainbow trout, Oncorhynchus mykiss
- MeSH Terms
- Amino Acid Sequence
- Base Sequence
- Carbonic Anhydrases/genetics*
- Carbonic Anhydrases/metabolism
- Carbonic Anhydrases/physiology
- Circadian Rhythm*
- DNA, Complementary
- Ear, Inner/anatomy & histology
- Ear, Inner/enzymology*
- Gene Expression Regulation, Enzymologic*
- Molecular Sequence Data
- Oncorhynchus mykiss/anatomy & histology
- Oncorhynchus mykiss/genetics*
- Oncorhynchus mykiss/metabolism
- Otolithic Membrane/enzymology*
- 16996283 Full text @ Comp. Biochem. Physiol. B Biochem. Mol. Biol.
Tohse, H., Murayama, E., Ohira, T., Takagi, Y., and Nagasawa, H. (2006) Localization and diurnal variations of carbonic anhydrase mRNA expression in the inner ear of the rainbow trout Oncorhynchus mykiss. Comparative biochemistry and physiology. Part B, Biochemistry & molecular biology. 145(3-4):257-264.
Physiological studies have suggested that carbonic anhydrase (CA) plays a central role in otolith biomineralization via ion transport. However, the presence and exact function of CA in the inner ear have not been determined. In the present study, to investigate the localization of CA and its involvement in otolith calcification, we cloned two cDNAs encoding CAs from the rainbow trout sacculus. These two cDNAs, designated rainbow trout CAa (rtCAa) and rtCAb, both had an open reading frame encoding 260 amino acids with a sequence identity of 78%. Remarkably, rtCAb has a high degree of homology (82%) with "high activity CA" in the zebrafish, and its mRNA expression showed variation in the range 1.9-11.4x10(4) copies/ng total RNA in the sacculus. In contrast, rtCAa mRNA was constantly expressed at approximately 3x10(4) copies/ng total RNA. In situ hybridization revealed that rtCAb mRNA was strongly expressed in the distal squamous epithelial cells and transitional epithelial cells, except the mitochondria-rich cells, whereas, rtCAa was localized in extrasaccular tissue. These results suggest that the rtCAb isozyme is involved in the daily increment formation and calcification of otoliths via phase and spatial differences of the bicarbonate supply to the endolymph.
Genes / Markers
Mutations / Transgenics
Human Disease / Model
Sequence Targeting Reagents
Engineered Foreign Genes