Affiliations 

  • 1 Department of Biological Science and Technology, China Medical University, Taichung, 402, Taiwan
  • 2 Institute of Tropical Aquaculture, University Malaysia Terengganu, 21030, Kuala Terengganu, Terengganu, Malaysia
  • 3 Department of Oceanography, National Sun Yat-sen University, 70 Lienhai Road, Kaohsiung, 804, Taiwan
  • 4 Institute of Biotechnology, National Cheng Kung University, Tainan, 701, Taiwan
  • 5 National Museum of Marine Biology and Aquarium, Checheng Township, Pingtung, 944, Taiwan
  • 6 School of Environmental and Natural Resource Sciences, University of Malaysia, 43600, Bangi, Selangor, Malaysia
  • 7 Department of Oceanography, National Sun Yat-sen University, 70 Lienhai Road, Kaohsiung, 804, Taiwan. wtang@mail.nsysu.edu.tw
Fish Physiol Biochem, 2018 Apr;44(2):489-502.
PMID: 29192359 DOI: 10.1007/s10695-017-0448-y

Abstract

The mosquitofish (Gambusia affinis) naturally inhabits freshwater (FW; 1-3‰) and seawater (SW; 28-33‰) ponds in constructed wetland. To explore the physiological status and molecular mechanisms for salinity adaptation of the mosquitofish, cytoprotective responses and osmoregulation were examined. In the field study, activation of protein quality control (PQC) mechanism through upregulation of the abundance of heat shock protein (HSP) 90 and 70 and ubiquitin-conjugated proteins was found in the mosquitofish gills from SW pond compared to the individuals of FW pond. The levels of aggregated proteins in mosquitofish gills had no significant difference between FW and SW ponds. Furthermore, the osmoregulatory responses revealed that the body fluid osmolality and muscle water contents of the mosquitofish from two ponds were maintained within a physiological range while branchial Na+/K+-ATPase (NKA) expression was higher in the individuals from SW than FW ponds. Subsequently, to further clarify whether the cellular stress responses and osmoregulation were mainly induced by hypertonicity, a laboratory salinity acclimation experiment was conducted. The results from the laboratory experiment were similar to the field study. Branchial PQC as well as NKA responses were induced by SW acclimation compared to FW-acclimated individuals. Taken together, induction of gill PQC and NKA responses implied that SW represents an osmotic stress for mosquitofish. Activation of PQC was suggested to provide an osmoprotection to prevent the accumulation of aggregated proteins. Moreover, an increase in branchial NKA responses for osmoregulatory adjustment was required for the physiological homeostasis of body fluid osmolality and muscle water content.

* Title and MeSH Headings from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.