Nitrogen Metabolism

Claybrook, David L.

doi:10.1016/b978-0-12-106405-1.50014-x

Cited by 101 publications

(79 citation statements)

References 176 publications

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“…Hagerman (1983) refers to a 15-fold intraspecific variation in haemolyrnph protein concentration, and brief examination of the hterature reveals wide variation in interspecific values also (Table 1). This led Claybrook (1983) Leone (1953) consequently total protein levels) to be rather low in decapods. This she interprets as a limitation imposed by crustacean circulatory systems which are ,,open" and operate at very low hydrostatic pressures.…”

Section: Haemolymph Protein Compositionmentioning

confidence: 99%

“…However, it is worth noting the heterogeneity of haemocyanins in decapod haemolymph, with 3 or 4 components present. These are subunit aggregations of haemocyanin (Manwell & Baker, 1963;Claybrook, 1983), and range in size from 450 • 103 to 1.7 x 106 daltons (Mangum, 1983). In general, haemocyanins exhibit low oxygen affinity, considerable cooperativity and a large Bohr effect (Mangurn, 1983).…”

Section: Haemolymph Protein Compositionmentioning

confidence: 99%

“…Up to 18 distinct protein bands have been recognised in electrophoretic studies of decapod haemolymph (Ceccaldi, 1968;Claybrook, 1983). These components can be assigned to one of 5 groups.…”

Section: Haemolymph Protein Compositionmentioning

confidence: 99%

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Haemolymph protein composition and copper levels in decapod crustaceans

Depledge¹,

Bjerregaard²

1989

Helgolander Meeresunters

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Variations in haemolymph protein composition and concentration, in copper content and copper distribution in the tissue of decapod crustaceans are reviewed. Haemocyanin is the major haemolymph constituent (> 60 %); the remaining proteins (in order of concentration) incIude coagulogen, apohaemocyanin, hormones and antisomes. Moulting, nutritional state, infection, hypoxia and salinity fluctuations are the major factors affecting the relative proportions and total quantities of the haemolymph proteins. With regard to haemocyanin, the changes in concentration during the moult cycle are principally associated with changes in haemolymph volume, rather than with changes in total haemocyanin content due to synthesis or catabolism. The role of the midgut gland in regulating haemolymph copper and haemocyanin concentration has been re-evaluated. More than 50 % of the whole body copper load is stored in the haemolymph. In contrast, less than 3 % of the copper load resides in the midgut gland. The latter has little potential for regulating haemolymph copper levels, at least in the short term (hours to a few days), though it may be involved in regulating haemocyanin levels over longer periods (weeks to months). The total coppe r content of the haemolymph remains within a narrow range, except during starvation when levels may decrease. Consequently, variations in the copper content of soft tissues, which constitute only 20 % of decapod dry weight, do not significantly alter whole body copper concentrations. Evidence that copper released following haemocyanin catabolism becomes bound to metallothionein for later use in the resynthesis of haemocyanin is reviewed and found to be inqonclusive. The amount of copper that can be stored in this way is trivial compared with the amount of copper required to permit significant changes in haemolymph haemocyanin concentration. Average tissue copper requirements, calculated during the present study, are approx. 4 times higher than previous theoretical estimates.

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Section: Haemolymph Protein Compositionmentioning

confidence: 99%

Section: Haemolymph Protein Compositionmentioning

confidence: 99%

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Haemolymph protein composition and copper levels in decapod crustaceans

Depledge¹,

Bjerregaard²

1989

Helgolander Meeresunters

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“…In crustaceans, metabolic pathways Involved in nitrogen excretion are catabolism of amino acid (including certain amides), deamination of purine nucleotides with the formation of ammonia, uricolysis and the ornithine-urea cycle with the formation of urea, and degradation of nucleic acid with the formation of uric acid (Claybrook 1983, Regnault 1987. The ornithine-urea cycle initiates with the fixation of metabolic product of NH,' and HCO3-which is supplied from CO, through carbonic anhydrase.…”

Section: Sallnlty (Ppt)mentioning

confidence: 99%

Hemolymph ammonia and urea and nitrogenous excretions of Scylla serrata at different temperature and salinity levels

Chen¹,

Pg²

1996

Mar. Ecol. Prog. Ser.

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Hemolymph ammonia and urea levels and nitrogenous excretions of Scylla serrala (Forskal) (202 * 18 g) were measured when the crabs were exposed to 9 different temperature and salinity regimes (15. 25. 35OC combined with 10, 25 and 40?L S). Hemolymph ammonia increased with a decrease in salinity, whereas hemolymph urea increased with a n increase in salinity. Nitrogenous excretion Increased with temperature. Excretion of ammonia-N, organic-N, nitrite-N, and nitrate-N and total nitrogen excretion (pg g-1 h I J increased with a decrease in salinity, whereas urea-N excret~o n increased w t h a n increase in salinity. At 25"C, ammonia-N excret~on accounted for 82 0, 79 2 and 56.2% of total nitrogen excreted by the crabs at 10, 25 and 40'!6, S, whereas urea-N excretion accounted for 4.3, 9.1 and 30 1 "t rcspectively It 1s concluded that the S. serrata at 40% S shlfts its excretory pattern from ammonlotr~lism to ureotelism.

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“…It is difficult to put these urea amounts into context, as there have been practically no studies on urea liberation by freshwater Crustacea and we certainly have found none on Daphnia. However, according to Claybrook (1983), Crustaceae are generally only supposed to liberate between 1 and 12% of their excreted N as urea. It should be noted that these values are based mostly on marine organisms and only one or two freshwater crustaceans.…”

Section: Discussionmentioning

confidence: 99%

Max Planck Institute for Limnology, P.O. Box 165, 24302 Plön, Germany

Wiltshire

Lampert

1999

Limnology & Oceanography

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It is known that the zooplankter Daphnia induces colonies in the alga Scenedesmus. As Daphnia grazes on Scenedesmus, it has been postulated that colony formation represents an algal defense mechanism. This induction of Scenedesmus coenobia/colonies by Daphnia could be associated with a substance exuded by the animals that acts as a specific infochemical (kairomone) for Scenedesmus. However, the chemical nature of such a substance is still unknown. Because coenobia can be formed in the absence of Daphnia kairomone, as a result of different N concentrations in the algae and media, we checked different nitrogen excretory products of Daphnia as potential candidates. In this paper we test the hypothesis that ammonia and urea excreted by zooplankters (Daphnia) may induce coenobia formation in Scenedesmus. Using experiments with dialysis separation of Daphnia and algae we show that one of the excretory products of zooplankters, urea, can induce colony formation in Scenesdesmus, whereas ammonia has no effect. Although the effect of urea on coenobia formation may simply be a nutrient effect, this does not exclude the possibility that it results in grazing protection of the algae. Hence, urea produced by zooplankton may serve as a colony inducer to algae.The induction of colonies in the alga Scenedesmus by the zooplankter Daphnia has been the subject of many studies. This is mainly due to the original work by Hessen and van Donk (1993), which that showed that when Daphnia magna and Daphnia water were introduced to single-celled cultures of Scenedesmus subspicatus, the algae formed coenobia (the term coenobium is often used for Scenedesmus colonies, although strictly speaking the definition of coenobium is ''a colony of unicellular organisms having a definite form and organisation, which behaves as an individual and reproduces to give daughter coenobia'' [Lawrence 1997]) and that spine formation was also enhanced. Lampert et al. (1994) followed up this work and showed that coenobia were induced by adding Daphnia water to single-celled cultures of Scenedesmus acutus (now known to be Scenedesmus obliquus, strain SAG 276-3a, Göttingen, Hegewald). Both sets of authors showed that Daphnia had to be fed in order for colony induction to occur.As Daphnia is a grazer on Scenedesmus, it has been postulated that colony formation represents an algal defense mechanism (Hessen and van Donk 1993). However, the extensive work of van showed that colony induction of Scenedesmus is not specific to Daphnia magna. Indeed most cladocerans, a copepod (Eudiaptomus gracilis), and some rotifers seem to induce colony formation in S. acutus/obliquus. In terms of the postulated algal defense mechanism, this is rather intriguing, as some of these organisms are not known to consume Scenedesmus. Other incongruities have been revealed by Lürling and others (Lür-ling andvan Donk 1996, 1997; Lürling et al. 1997) in studies on the differences between single-celled and multicelled Scenedesmus in terms of food quality for ingesting Daphnia. Acknowled...

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Nitrogen Metabolism

Cited by 101 publications

References 176 publications

Haemolymph protein composition and copper levels in decapod crustaceans

Haemolymph protein composition and copper levels in decapod crustaceans

Hemolymph ammonia and urea and nitrogenous excretions of Scylla serrata at different temperature and salinity levels

Max Planck Institute for Limnology, P.O. Box 165, 24302 Plön, Germany

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