Identification and Localization of H+-ATPase, NHE2 AND NHE3 in the Gills of the Southern Appalachian Brook Trout, Salvelinus fontinalis
Mikeworth BP. 2012. Identification and Localization of H+-ATPase, NHE2 AND NHE3 in the Gills of the Southern Appalachian Brook Trout, Salvelinus fontinalis. Appalachian State University
Southern brook trout (Salvelinus fontinalis) native to the Great Smoky Mountains are found in headwater streams. These habitats have recently been experiencing increasing instances of stream acidification, lowering stream pH on average ~1.0 pH unit (Deyton et al., 2009). Stream acidification was directly correlated with a decrease in whole-body Na+ in southern brook trout, which can cause sub-lethal to lethal stress ultimately resulting in fish mortality (Neff et al., 2009). It is well documented that lowering environmental pH results in fish experiencing systemic acidosis. We hypothesize that during acidification events brook trout are suffering a physiological acid/base perturbation. Previous studies on other species of freshwater fishes have demonstrated an alteration in the relative expression of H+-ATPase, NHE2 and NHE3 in gill tissue during pH disturbances (Perry et al., 2000; Hirata et al., 2003; Yan et al., 2007). Due to a lack of physiological information available, the mechanism utilized by S. fontinalis to regulate systemic pH is unknown. We hypothesized that S. fontinalis will utilize H+-ATPase, NHE2 and NHE3 to excrete excess protons when experiencing episodic stream acidification. To date, we have cloned an ORF for H+-ATPase (1,376 bp) NHE2 (1,485 bp) and NHE3 (2,100 bp) which are homologous to rainbow trout (87, 94 and 92% identical respectively). Immunohistochemical analysis demonstrated that H+-ATPase, NHE2 and NHE3 expression is localized to the apical membrane and sub-apical regions of the mitochondia-rich cells in gill epithelia. Also, the relative expression of H+-ATPase was found to decrease along the elevation gradient, whereas NHE3 does not. This suggests that brook trout regulate H+-ATPase expression in response to systemic acidosis, where NHE3 may play a role in Na+ absorption.
- Type
- Academic
- Authors
- Mikeworth, Brian
- Date of Issue
- 2012-05
- Publisher
- Appalachian State University
- Units
- GRSM
- Keywords
- APHN, Appalachian Highlands Network, Brook Trout, Great Smoky Mountains National Park, GRSM, GRSM-01067, immunohistochemical analysis, pH, Road Prong, SER, sodium absorption, Southeast Region, stream acidification, Stress, thesis
- Subjects
- Ecological Framework: Biological Integrity | Focal Species or Communities | Fishes