Differential expression of Na+/D-glucose cotransport in isolated cells of Marsupenaeus japonicus hepatopancreas.
D-Glucose absorptive processes at the gastrointestinal tract of decapod crustaceans are largely under-investigated. We have studied Na(+)-dependent D-glucose transport (Na(+)/D-glucose cotransport) in the hepatopancreas of the Kuruma prawn, Marsupenaeus japonicus, using both brush-border membrane vesicles and purified R and B hepatopancreatic cell suspensions. As assessed by brush-border membrane vesicle studies, Na(+)/D-glucose cotransport was inhibited by phloridzin and responsive to the (inside negative) membrane potential. Furthermore, it was strongly activated by protons (although only in the presence of an inside-negative membrane potential), which correlates with the fact that the lumen of crustacean hepatopancreatic tubules is acidic. When assayed in purified R and B cell suspensions, Na(+)/D-glucose cotransport activity was restricted to B cells only. Mab 13, a monoclonal antibody recognizing an 80- to 85-KDa protein at the brush-border membrane location, inhibited Na(+)/D-glucose cotransport in brush-border membrane vesicles as well as in enriched B cell suspensions. Primers designed after comparison of highly homologous regions of various mammalian sodium-glucose transporter) nucleotide sequences failed to produce RT-PCR amplification products from Kuruma prawn hepatopancreatic RNA. The molecular nature of this Na(+)/D-glucose cotransport system is still to be established.
Vilella
S
S
Laboratory of General and Comparative Physiology, Department of Biological and Environmental Sciences and Technologies, University of Lecce, Via Provinciale Lecce-Monteroni, 73100 Lecce, Italy. sebastiano.vilella@unile.it
Zilli
L
L
Ingrosso
L
L
Schiavone
R
R
Zonno
V
V
Verri
T
T
Storelli
C
C
D000818:Animals; D000911:Antibodies, Monoclonal / Q000378:metabolism / Q000494:pharmacology*; D001692:Biological Transport / Q000187:drug effects / Q000502:physiology; D003445:Crustacea / Q000502:physiology*; D005947:Glucose / Q000378:metabolism*; D043143:Hepatopancreas / Q000166:cytology*; D007150:Immunohistochemistry; D007700:Kinetics; D008564:Membrane Potentials / Q000187:drug effects; D008871:Microvilli / Q000378:metabolism; D009004:Monosaccharide Transport Proteins / Q000187:drug effects / Q000378:metabolism*; D010695:Phlorhizin / Q000494:pharmacology; D012964:Sodium / Q000378:metabolism*
D000911:Antibodies, Monoclonal; D009004:Monosaccharide Transport Proteins; D012964:Sodium; D010695:Phlorhizin; D005947:Glucose