Modification of morphology and function of integument mitochondria-rich cells in tilapia larvae (Oreochromis mossambicus) acclimated to ambient chloride levels.
Similar to those of the gills of adults, three types of mitochondria-rich (MR) cells with different morphologies of apical surfaces (wavy convex, shallow basin, and deep hole) were identified on the integument of freshwater-acclimated tilapia larvae (Oreochromis mossambicus). The object of this study is to test the hypothesis that these subtype cells may represent MR cells equipped with variable efficiencies in Cl(-) uptake. Larvae acclimated to low-Cl(-) =0.001-0.007 mM) water developed higher densities of MR cells than those acclimated to high-Cl(-) =7.3-7.9 mM) water. The percentage of wavy-convex-type cells in total MR cells was higher in low-Cl(-)-acclimated larvae than in high-Cl(-)-acclimated larvae, which displayed only deep-hole type. In addition, Cl(-) influx rates of whole larva measured with (36)Cl(-) showed a coincident correlation with MR cell densities, that is, low-Cl(-) larvae displayed higher Cl(-) influx rates than did high-Cl(-) larva, suggesting that tilapia larvae develop a higher density of MR cells with larger apical surfaces (wavy-convex type) to boost Cl(-) uptake in Cl(-)-deficient water. The distinct types of apical surfaces may represent different phases of MR cells that possess different efficiencies of Cl(-) uptake. Increased apical membrane surface areas of MR cells may provide larvae with rapid regulation of Cl(-) before new MR cells differentiate.
Lin
L Y
LY
Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan, Republic of China.
Hwang
P P
PP
D000818:Animals; D002712:Chlorides / Q000493:pharmacokinetics / Q000494:pharmacology* / Q000502:physiology; D005260:Female; D008855:Microscopy, Electron, Scanning / Q000662:veterinary; D008928:Mitochondria / Q000378:metabolism / Q000502:physiology* / Q000648:ultrastructure; D017210:Tilapia / Q000033:anatomy & histology / Q000378:metabolism / Q000502:physiology*
D002712:Chlorides