Gill-specific (Na(+), K(+))-ATPase activity and α-subunit mRNA expression during low-salinity acclimation of the ornate blue crab Callinectes ornatus (Decapoda, Brachyura).
We evaluate (Na(+), K(+))-ATPase activity, and protein and gene expression of the α-subunit in posterior gills 6 and 7 of Callinectes ornatus, a euryhaline crab, during a 10-day acclimation period from seawater (33‰ S) to low salinity (21‰ S). (Na(+), K(+))-ATPase activity decreased within 1h after transfer to 21‰ S, values recovering by 24h and attaining a maximum of ≈180 nmol Pi min(-1) mg(-1) after 10 days (≈2.5-fold increase). (Na(+), K(+))-ATPase activity is ≈1.5-fold greater in gill 6 than in gill 7, independently of salinity. Relative expression of (Na(+), K(+))-ATPase α-subunit mRNA increased in both gills within 1- to 2-h exposure to low salinity, reaching an ≈8-fold maximum after 24-h exposure, decreasing slightly by 10 days acclimation to low salinity. This increase in α-subunit mRNA expression may underpin the increased (Na(+), K(+))-ATPase activity seen after 10 days acclimation to low salinity. Enzyme affinity for ATP was greater in gill 6 than in gill 7, in contrast to ouabain affinity that was greater in gill 7. Western blotting analysis identified a single immunoreactive band against the (Na(+), K(+))-ATPase α-subunit with an Mr of ≈105 kDa, independently of gill number and low salinity acclimation. Despite these differences, gills 6 and 7 appear to perform similar functions in salt uptake from the dilute medium. The partial cDNA sequence obtained for the gill (Na(+), K(+))-ATPase of C. ornatus (GenBank deposit KF056804) showed 97 to 91% identities with similar sequences from other portunid crab gills. The regulation of gill (Na(+), K(+))-ATPase activity during acclimation to low salinity is discussed.
Departamento de Química, Faculdade de Filosofia Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Brazil. Electronic address: fdaleone@ffclrp.usp.br.
Francisco A
FA
Leone
Departamento de Química, Faculdade de Filosofia Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Brazil.
Daniela P
DP
Garçon
Departamento de Química, Faculdade de Filosofia Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Brazil.
Malson N
MN
Lucena
Departamento de Biologia, Faculdade de Filosofia Ciências e Letras de Ribeirão Preto, and Centro de Biologia Marinha, Universidade de São Paulo, Brazil.
Rogério O
RO
Faleiros
Departamento de Genética, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Brazil.
Sergio V
SV
Azevedo
Departamento de Química, Faculdade de Filosofia Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Brazil.
Marcelo R
MR
Pinto
Departamento de Biologia, Faculdade de Filosofia Ciências e Letras de Ribeirão Preto, and Centro de Biologia Marinha, Universidade de São Paulo, Brazil.
John C
JC
McNamara
D000064:Acclimatization; D000818:Animals; D060829:Arthropod Proteins / Q000378:metabolism*; D003386:Brachyura / Q000201:enzymology* / Q000502:physiology*; D005880:Gills / Q000201:enzymology* / Q000378:metabolism; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000378:metabolism; D054712:Salinity; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*
D060829:Arthropod Proteins; D012333:RNA, Messenger; D000254:Sodium-Potassium-Exchanging ATPase
(Na(+), K(+))-ATPase activity; (Na(+), K(+))-ATPase mRNA expression; Callinectes ornatus; Gill; Low salinity acclimation