Transport of amino acids by marine invertebrates

Abstract

Marine invertebrates transport amino acids and other organic solutes across their body surfaces. This surface absorption, in some instances, may contribute significantly to the overall nutritional requirements for an organism. Amino acids are accumulated against gradients as high as 106:1 to 107:1 (intracellular:extracellular concentration). The transport mechanism that has been consistently observed to account for this process is Na dependent cotransport. A review of the general characteristics of these transport systems characterized in marine invertebrate epithelia indicates certain common features: Na dependency with coupling coefficients of 2:1 or 3:1 (Na:amino acid translocated), influx coupled to membrane potential, and low intracellular Na activity. Under these conditions Na cotransport can readily account for gradients approaching 107:1. These transport systems may play a role in acquisition of nutrients by marine invertebrates, but it has also been suggested that they may play additional roles in osmoregulation, nutrient conservation, and chemo‐reception. © 1993 Wiley‐Liss, Inc.

Benzo(a)pyrene-induced metabolic responses in Manila clam Ruditapes philippinarum by proton nuclear magnetic resonance (1H NMR) based metabolomics

“…It is well known as a competitive inhibitor of cellular respiration since it binds to the active site of the succinate dehydrogenase in the tricarboxylic acid cycle. Organic osmolytes such as betaine, homarine, hypotaurine, dimethylamine, alanine (also involved in energy metabolism) and taurine are small organic molecules functioning in the osmotic regulation in marine organisms via various metabolic pathways (Preston, 2005). The osmolytes can be actively accumulated or released when the salinity increase or decreases.…”

“…The osmolytes can be actively accumulated or released when the salinity increase or decreases. Therefore, organic osmolytes play key physiological roles in osmotic regulation of invertebrates and were therefore detected at higher levels than other metabolites in clams (Preston, 2005).…”

Metabolic responses in gills of Manila clam Ruditapes philippinarum exposed to copper using NMR-based metabolomics

“…1A), which were 10e100 times higher in NMR peak intensities than other metabolites. Organic osmolytes such as betaine, homarine, hypotaurine, dimethylamine, alanine and taurine are small organic molecules functioning in the osmotic regulation in marine organisms via various metabolic pathways (Preston, 2005). The osmolytes can be actively accumulated or released when the salinity increase or decreases.…”

“…The osmolytes can be actively accumulated or released when the salinity increase or decreases. Therefore, organic osmolytes play key physiological roles in osmotic regulation of invertebrates and were therefore detected at higher levels than other metabolites in clams (Preston, 2005). In the clam gills after 24 h of exposure of Cu, the elevation of hypotaurine and reduction of alanine in low (10 mg L À1 ) dose of Cu-treated samples exhibited separations between control (;), 10 (C) and 40 mg L À1 Cu-exposed (-) clam samples after exposure for 24 h (Q 2 ¼ 0.57); and corresponding LV1 (B) and LV2 (C) weights plots showing the metabolic differences between the groups.…”

A metabolomic investigation of the effects of metal pollution in oysters Crassostrea hongkongensis

“…In a previous study, Zhang et al (2011) found that alanine was significantly decreased in Cu-exposed clams Ruditapes philippinarum and suggested that this decrease was a marker of disturbed osmotic regulation induced by Cu. As a matter of fact, alanine is not only involved in anaerobic metabolism, but is another small organic osmolyte in marine bivalves (Preston, 1993). Interestingly, Cu was the most efficiently accumulated metal in oyster gills sampled from BJ.…”