Effects of acclimation salinity on the expression of proteins G0 and Gi in the gills of Chasmagnatus granulatus (Decapoda, Grapsidae)

HALPERIN, J., CARMANCHAHI, P., LUQUET, C., PAZ, D..

Liége, Belgica

Congreso; 21rst European Society for Comparative Physiology and Biochemistry.; 2000

ESCPB

Chasmagnathus granulatus is a hyper-hyporegulating species thought to regulate its internal ionic concentrations by active transport through the posterior gills. The aim of this work is to identify membrane proteins that could mediate the regulation of the activity and/or the structure of the gill in response to changes in external salinity. G proteins are heterotrimeric transmembrane proteins involved in signal transduction processes, reported as modulating ion transport, thus they become candidates to participate in this regulatory response. Gills 3 (representative of respiratory gills) and 7 (representative of ionoregulatory gills) were dissected and fixed in Bouin´s fluid. Then they were processed by routine histological techniques and treated by immunohistochemical techniques for detecting cz subunits of proteins Go and Gi. Gill 7 was studied in crabs chronically (at least one week) acclimated to 12, 30 or 44%0 and after acute transference (24 hours) from 12 to 30 or 44%0. Protein Go immunoreactivity was clearly evident in ionoregulatory cells of gill 7 but hardly visible or absent in respiratory ceils of the gill 3. In contrast the expression of Gi was scarce in both gills. For chronically adapted crabs, the expression of protein Go was abundant at 10%o but nearly absent at high salinities (30%0 and 44%0). Gi immunoreactivity was scarce at the three salinities. Go expression was clearly reduced after acute transference from 10%o to 30%0 and 44%0. In contrast, abundant immunostaining for Gi was observed after transference to 44%0. These results show differential expression of Go in the ion transport epithelium of posterior gills, suggesting an involvement of this protein in the regulation of ion transport processes. In crabs acclimated to dilute seawater, ion transport by the gills is modulated by changes in salinity. This modulation could be mediated by phosphorylation of Na+/H ÷ exchangers or another transport protein, by Protein kinase C, activated by a phosphorylation cascade originated by stimulation of a membrane receptor coupled to Go. Protein G~ seems to be related to the changes occurring in the posterior gill epithelium during acclimation to a different salinity involving a change in the direction of the ionic gradient. transport through the posterior gills. The aim of this work is to identify membrane proteins that could mediate the regulation of the activity and/or the structure of the gill in response to changes in external salinity. G proteins are heterotrimeric transmembrane proteins involved in signal transduction processes, reported as modulating ion transport, thus they become candidates to participate in this regulatory response. Gills 3 (representative of respiratory gills) and 7 (representative of ionoregulatory gills) were dissected and fixed in Bouin´s fluid. Then they were processed by routine histological techniques and treated by immunohistochemical techniques for detecting cz subunits of proteins Go and Gi. Gill 7 was studied in crabs chronically (at least one week) acclimated to 12, 30 or 44%0 and after acute transference (24 hours) from 12 to 30 or 44%0. Protein Go immunoreactivity was clearly evident in ionoregulatory cells of gill 7 but hardly visible or absent in respiratory ceils of the gill 3. In contrast the expression of Gi was scarce in both gills. For chronically adapted crabs, the expression of protein Go was abundant at 10%o but nearly absent at high salinities (30%0 and 44%0). Gi immunoreactivity was scarce at the three salinities. Go expression was clearly reduced after acute transference from 10%o to 30%0 and 44%0. In contrast, abundant immunostaining for Gi was observed after transference to 44%0. These results show differential expression of Go in the ion transport epithelium of posterior gills, suggesting an involvement of this protein in the regulation of ion transport processes. In crabs acclimated to dilute seawater, ion transport by the gills is modulated by changes in salinity. This modulation could be mediated by phosphorylation of Na+/H ÷ exchangers or another transport protein, by Protein kinase C, activated by a phosphorylation cascade originated by stimulation of a membrane receptor coupled to Go. Protein G~ seems to be related to the changes occurring in the posterior gill epithelium during acclimation to a different salinity involving a change in the direction of the ionic gradient. transport through the posterior gills. The aim of this work is to identify membrane proteins that could mediate the regulation of the activity and/or the structure of the gill in response to changes in external salinity. G proteins are heterotrimeric transmembrane proteins involved in signal transduction processes, reported as modulating ion transport, thus they become candidates to participate in this regulatory response. Gills 3 (representative of respiratory gills) and 7 (representative of ionoregulatory gills) were dissected and fixed in Bouin´s fluid. Then they were processed by routine histological techniques and treated by immunohistochemical techniques for detecting cz subunits of proteins Go and Gi. Gill 7 was studied in crabs chronically (at least one week) acclimated to 12, 30 or 44%0 and after acute transference (24 hours) from 12 to 30 or 44%0. Protein Go immunoreactivity was clearly evident in ionoregulatory cells of gill 7 but hardly visible or absent in respiratory ceils of the gill 3. In contrast the expression of Gi was scarce in both gills. For chronically adapted crabs, the expression of protein Go was abundant at 10%o but nearly absent at high salinities (30%0 and 44%0). Gi immunoreactivity was scarce at the three salinities. Go expression was clearly reduced after acute transference from 10%o to 30%0 and 44%0. In contrast, abundant immunostaining for Gi was observed after transference to 44%0. These results show differential expression of Go in the ion transport epithelium of posterior gills, suggesting an involvement of this protein in the regulation of ion transport processes. In crabs acclimated to dilute seawater, ion transport by the gills is modulated by changes in salinity. This modulation could be mediated by phosphorylation of Na+/H ÷ exchangers or another transport protein, by Protein kinase C, activated by a phosphorylation cascade originated by stimulation of a membrane receptor coupled to Go. Protein G~ seems to be related to the changes occurring in the posterior gill epithelium during acclimation to a different salinity involving a change in the direction of the ionic gradient. is a hyper-hyporegulating species thought to regulate its internal ionic concentrations by active transport through the posterior gills. The aim of this work is to identify membrane proteins that could mediate the regulation of the activity and/or the structure of the gill in response to changes in external salinity. G proteins are heterotrimeric transmembrane proteins involved in signal transduction processes, reported as modulating ion transport, thus they become candidates to participate in this regulatory response. Gills 3 (representative of respiratory gills) and 7 (representative of ionoregulatory gills) were dissected and fixed in Bouin´s fluid. Then they were processed by routine histological techniques and treated by immunohistochemical techniques for detecting cz subunits of proteins Go and Gi. Gill 7 was studied in crabs chronically (at least one week) acclimated to 12, 30 or 44%0 and after acute transference (24 hours) from 12 to 30 or 44%0. Protein Go immunoreactivity was clearly evident in ionoregulatory cells of gill 7 but hardly visible or absent in respiratory ceils of the gill 3. In contrast the expression of Gi was scarce in both gills. For chronically adapted crabs, the expression of protein Go was abundant at 10%o but nearly absent at high salinities (30%0 and 44%0). Gi immunoreactivity was scarce at the three salinities. Go expression was clearly reduced after acute transference from 10%o to 30%0 and 44%0. In contrast, abundant immunostaining for Gi was observed after transference to 44%0. These results show differential expression of Go in the ion transport epithelium of posterior gills, suggesting an involvement of this protein in the regulation of ion transport processes. In crabs acclimated to dilute seawater, ion transport by the gills is modulated by changes in salinity. This modulation could be mediated by phosphorylation of Na+/H ÷ exchangers or another transport protein, by Protein kinase C, activated by a phosphorylation cascade originated by stimulation of a membrane receptor coupled to Go. Protein G~ seems to be related to the changes occurring in the posterior gill epithelium during acclimation to a different salinity involving a change in the direction of the ionic gradient.