Salinity-stimulated changes in expression and activity of two carbonic anhydrase isoforms in the blue crabCallinectes sapidus

Jun 19, 2007The Journal of experimental biology

Salt levels change the activity and production of two carbonic anhydrase enzymes in blue crabs

AI simplified

Circadian Biology on OpenScience ↗PubMed ↗DOI ↗

Abstract

The cytoplasmic isoform of carbonic anhydrase in blue crab gills shows a 100-fold increase in mRNA expression when exposed to low salinity (15 p.p.t.).

Two isoforms of carbonic anhydrase, CasCAg and CasCAc, were identified in blue crab gills.
The membrane-associated isoform, CasCAg, has higher mRNA levels in crabs acclimated to high salinity (35 p.p.t.).
After exposure to low salinity, the cytoplasmic isoform, CasCAc, undergoes significant up-regulation, suggesting a role in overcoming diffusion limitations.
The expression of CasCAc corresponds with increased protein-specific carbonic anhydrase activity and protein concentration.
No changes in carbonic anhydrase expression or activity were observed in the anterior gills.
The expression pattern of the Na+/K+-ATPase alpha-subunit mirrors that of CasCAc, indicating a coordinated response to low salinity.

AI simplified

Two isoforms of the enzyme carbonic anhydrase (CA) in the blue crab gill, CasCAg and CasCAc, were identified, sequenced, and found to match the membrane-associated and cytoplasmic isoforms, respectively. The membrane-associated isoform is present in much higher levels of mRNA expression in both anterior and posterior gills in crabs acclimated to high salinity (35 p.p.t.), but expression of the cytoplasmic isoform in the posterior gill undergoes a significantly greater degree of up-regulation after exposure to low salinity (15 p.p.t.). CasCAc has the largest scope of induction (100-fold) reported for any transport-related protein in the gill, and this may be necessary to overcome diffusion limitations between gill cytoplasm and the apical boundary layer. Furthermore, the timing of the changes in expression of CasCAc corresponds to the timing of the induction of protein-specific CA activity and CA protein concentration. No changes in CA mRNA expression or activity occur in the anterior gills. The pattern of up-regulation of expression of mRNA of the alpha-subunit of the Na+/K+-ATPase is similar to that for CasCAc, and both precede the establishment of the new acclimated physiological state of the crab in low salinity. A putative ;housekeeping' gene, arginine kinase, also showed about a threefold increase in expression in response to low salinity, but only in the posterior gills. These results suggest that for studies of expression in crustacean gill tissue, a control tissue, such as the anterior gill, be used until an adequate control gene is identified.

Full Text

Full text is available at the source.

View full text (PDF) ↗View full text ↗

Salinity-stimulated changes in expression and activity of two carbonic anhydrase isoforms in the blue crabCallinectes sapidus

Abstract

Full Text

You found one interesting study. We’ll send the next 7.

what lands in your inbox each week:

Recent issues from the circadian biology brief

Abstract

Full Text

Related papers

You found one interesting study. We’ll send the next 7.

what lands in your inbox each week:

Recent issues from the circadian biology brief