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Laser scanning cytometry and tissue microarray analysis of salinity effects on killifish chloride cells
1University of California, Davis, One Shields Avenue, Davis, CA 95616, USA.
The Journal of Experimental Biology
|April 10, 2004
Summary
Euryhaline killifish adapt to changing salinity by altering chloride cells (CCs). Their number and volume increase with salinity, while Na(+)/K(+)-ATPase content shows transient or permanent adjustments for survival.
Area of Science:
- Comparative physiology
- Environmental adaptation
- Cell biology
Background:
- Euryhaline fish, like Fundulus heteroclitus, must regulate internal ion balance across a wide range of environmental salinities.
- Chloride cells (CCs) in gill epithelium are crucial for ion transport and osmoregulation in fish.
- Understanding the cellular mechanisms of salinity adaptation is key to fish survival in changing aquatic environments.
Purpose of the Study:
- To investigate the effects of different salinity levels on chloride cell (CC) number, volume, and Na(+)/K(+)-ATPase content in the gill epithelium of euryhaline killifish.
- To compare the efficacy of acute versus gradual salinity acclimation on CC characteristics and Na(+)/K(+)-ATPase expression.
- To evaluate the utility of laser scanning cytometry (LSC) and tissue microarrays (TMAs) for analyzing cellular adaptations in fish gills.
Main Methods:
- Fundulus heteroclitus were subjected to acute (freshwater to 1x seawater) and gradual (freshwater to 2.4x seawater) salinity acclimation.
- Laser scanning cytometry (LSC) was used to quantify CC number and volume in dissociated gill cells stained with DASPMI.
- Tissue microarrays (TMAs) combined with Na(+)/K(+)-ATPase antibody staining allowed in situ visualization and quantification of CCs and their enzyme content.
Main Results:
- CC number and volume significantly increased with external salinity, being lowest in freshwater and highest in 2.4x seawater.
- Acute salinity increase led to a transient rise in Na(+)/K(+)-ATPase content per CC, which returned to baseline within 5 weeks.
- Gradual acclimation to high salinity resulted in a permanent increase in Na(+)/K(+)-ATPase content per CC.
Conclusions:
- Euryhaline fish possess sophisticated mechanisms to sense and adapt to environmental salinity through both short-term and long-term physiological adjustments.
- The study highlights the differential regulation of Na(+)/K(+)-ATPase in CCs depending on the rate of salinity change.
- Laser scanning cytometry and tissue microarrays are powerful tools for quantitative analysis of cellular adaptations in comparative biology.