Ocean acidification: synergistic inhibitory effects of protons and heavy metals on Ca uptake by lobster branchiostegite membrane vesicles.

Previous work with isolated outer membrane vesicles of lobster branchiostegite epithelial cells has shown that Ca uptake by these structures is significantly (p < 0.02) reduced by an incremental decrease in saline pH (increased proton concentration) and that this decrease is due to competitive inhibition between carrier-mediated transport of Ca and hydrogen ions. The present paper extends these previous findings and describes the combined effects of pH and cationic heavy metals on branchiostegite uptake of Ca.

Ocean acidification: effects of pH on Ca uptake by lobster branchiostegites.

Gill chambers of the Atlantic lobster, Homarus americanus, possess three structures that are involved with respiration and ion regulation: gill filaments, epipodites, and branchiostegites. This paper describes ion transport mechanisms present in the plasma membranes of branchiostegite epithelial cells and the effects of pH on the uptake of Ca by these processes. Partially purified membrane vesicles (PPMV) of branchiostegite cells were produced by a homogenization/centrifugation method that has previously been used to define ion transport processes in both crab and lobster gill tissues.

Functional characterization of a novel disaccharide transporter in lobster hepatopancreas.

In animals, the accepted model of carbohydrate digestion and absorption involves reduction of disaccharides into the monosaccharides glucose, fructose, and galactose followed by their individual transmembrane transport into cells. In 2011, a gene for a distinct disaccharide sucrose transporter (SCRT) was found in Drosophila melanogaster and characterized in a yeast expression system. The purpose of the present investigation was to functionally identify and characterize a putative disaccharide transporter analog in the hepatopancreas of the American lobster, Homarus americanus.

Molecular identification and functional characteristics of peptide transporters in the bonnethead shark (Sphyrna tiburo).

Elasmobranchs are considered to be top marine predators, and in general play important roles in the transfer of energy within marine ecosystems. Despite this, little is known regarding the physiological processes of digestion and nutrient absorption in these fishes. One topic that is particularly understudied is the process of nutrient uptake across the elasmobranch gastrointestinal tract.

Functional characterization of a putative disaccharide membrane transporter in crustacean intestine.

Transepithelial absorption of dietary sucrose in the American lobster, Homarus americanus, was investigated by mounting an intestine in a perfusion chamber to characterize mucosal to serosal (MS) (14)C-sucrose transport. These fluxes were measured by adding varying concentrations of (14)C-sucrose to the perfusate and monitoring their appearance in the bathing solution. Transepithelial (14)C-sucrose transport was the combination of a hyperbolic function of luminal concentration, following Michaelis-Menten kinetics, and apparent diffusion.