Absorption ofL-alanine and other dissolved nutrients by the spines ofParacentrotus lividus(Echinoidea)

Abstract

The possibility that marine invertebrates might obtain part of their nutritional requirements by direct absorption of dissolved molecules through the epidermis has recently received considerable attention. This revival of interest in a field which had been virtually abandoned since the early part of the century was led by the findings of Stephens & Schinske (1957, 1958, 1961). Modern analytical techniques have revealed that the amount of dissolved nutrients in coastal waters is much greater than was formerly realized; total amino acids have been recorded in concentrations of up to 10-4 mole/litre in south-east Alaskan waters (Schell, 1974) and 7 x 10-5 mole/litre off Helgoland (Bohling, 1970). Direct absorption of amino acids has been conclusively established in several phyla (see reviews by Stephens, 1968,1972), and one of the major aims of current research is to show that dissolved organic molecules taken up from available concentrations could be of nutritional significance. Recent developments concerning the possible roles of uptake in marine ecosystems have been reviewed by West, de Burgh & Jeal (1977).

Specificity of L-Alanine Transport in the Spine Epithelium of Paracentrotus Lividus (Echinoidea)

“…It has previously been shown (de Burgh et al 1977) that in Paracentrotus spine epithelium the decreasing order of uptake rates for a series of neutral amino acids was glycine > proline > L-alanine > D-alanine > leucine. In Table 1 we see that in terms of overall inhibitory effect on L-alanine uptake, leucine is the most powerful inhibitor, followed by proline, D-alanine, and glycine -almost exact reversal of the previous order.…”

Specificity of L-Alanine Transport in the Spine Epithelium of Paracentrotus Lividus (Echinoidea)

“…It has previously been shown (de Burgh et al 1977) that in Paracentrotus spine epithelium the decreasing order of uptake rates for a series of neutral amino acids was glycine > proline > L-alanine > D-alanine > leucine. In Table 1 we see that in terms of overall inhibitory effect on L-alanine uptake, leucine is the most powerful inhibitor, followed by proline, D-alanine, and glycine -almost exact reversal of the previous order.…”

Algal cover and sea urchin spatial distribution at Madeira Island (NE Atlantic)

“…Though it is preferentially herbivorous (Sammarco, 1982a, b;Kullen, 1996), D. antillarum can also be omnivorous (Carpenter, 1981), in what Lawrence (1975) considers as opportunistic feeding behaviour. Absorption of dissolved nutrients by the spines has been observed in P. lividus (De Burgh, 1975;Anonymous, 1996) and is yet another possible adaptive theory.…”

An ecosystem-based approach to assess the status of Mediterranean algae-dominated shallow rocky reefs

“…The regular sea urchins Paracentrotus lividus and Arbacia lixula, and to a much lesser extent Sphaerechinus granularis, are the main invertebrate grazers in Mediterranean algae-dominated rocky reefs. Sea urchins are capable of assimilating organic matter through their porous spines, enabling them to thrive in polluted waters and within habitats that are poor in primary producers (De Burgh, 1975;West et al, 1977;Régis, 1978Régis, , 1986. The abundance of these species is controlled by some fish, crustaceans, molluscs and other echinoderms (Dance and Savy, 1987;Sala, 1997;Guidetti, 2004;Hereu Fina, 2004;Hereu et al, 2005).…”

Specificity of L-Alanine Transport in the Spine Epithelium of Paracentrotus Lividus (Echinoidea)

“…It has previously been shown (de Burgh et al 1977) that in Paracentrotus spine epithelium the decreasing order of uptake rates for a series of neutral amino acids was glycine > proline > L-alanine > D-alanine > leucine. In Table 1 we see that in terms of overall inhibitory effect on L-alanine uptake, leucine is the most powerful inhibitor, followed by proline, D-alanine, and glycine -almost exact reversal of the previous order.…”

Algal cover and sea urchin spatial distribution at Madeira Island (NE Atlantic)

“…Though it is preferentially herbivorous (Sammarco, 1982a, b;Kullen, 1996), D. antillarum can also be omnivorous (Carpenter, 1981), in what Lawrence (1975) considers as opportunistic feeding behaviour. Absorption of dissolved nutrients by the spines has been observed in P. lividus (De Burgh, 1975;Anonymous, 1996) and is yet another possible adaptive theory.…”

An ecosystem-based approach to assess the status of Mediterranean algae-dominated shallow rocky reefs

“…The regular sea urchins Paracentrotus lividus and Arbacia lixula, and to a much lesser extent Sphaerechinus granularis, are the main invertebrate grazers in Mediterranean algae-dominated rocky reefs. Sea urchins are capable of assimilating organic matter through their porous spines, enabling them to thrive in polluted waters and within habitats that are poor in primary producers (De Burgh, 1975;West et al, 1977;Régis, 1978Régis, , 1986. The abundance of these species is controlled by some fish, crustaceans, molluscs and other echinoderms (Dance and Savy, 1987;Sala, 1997;Guidetti, 2004;Hereu Fina, 2004;Hereu et al, 2005).…”

Specificity of L-Alanine Transport in the Spine Epithelium of Paracentrotus Lividus (Echinoidea)

“…It has previously been shown (de Burgh et al 1977) that in Paracentrotus spine epithelium the decreasing order of uptake rates for a series of neutral amino acids was glycine > proline > L-alanine > D-alanine > leucine. In Table 1 we see that in terms of overall inhibitory effect on L-alanine uptake, leucine is the most powerful inhibitor, followed by proline, D-alanine, and glycine -almost exact reversal of the previous order.…”

Algal cover and sea urchin spatial distribution at Madeira Island (NE Atlantic)

“…Though it is preferentially herbivorous (Sammarco, 1982a, b;Kullen, 1996), D. antillarum can also be omnivorous (Carpenter, 1981), in what Lawrence (1975) considers as opportunistic feeding behaviour. Absorption of dissolved nutrients by the spines has been observed in P. lividus (De Burgh, 1975;Anonymous, 1996) and is yet another possible adaptive theory.…”

An ecosystem-based approach to assess the status of Mediterranean algae-dominated shallow rocky reefs

“…The regular sea urchins Paracentrotus lividus and Arbacia lixula, and to a much lesser extent Sphaerechinus granularis, are the main invertebrate grazers in Mediterranean algae-dominated rocky reefs. Sea urchins are capable of assimilating organic matter through their porous spines, enabling them to thrive in polluted waters and within habitats that are poor in primary producers (De Burgh, 1975;West et al, 1977;Régis, 1978Régis, , 1986. The abundance of these species is controlled by some fish, crustaceans, molluscs and other echinoderms (Dance and Savy, 1987;Sala, 1997;Guidetti, 2004;Hereu Fina, 2004;Hereu et al, 2005).…”