On the nutrition and metabolism of zooplankton XII. Measurements by radioimmunoassay of the levels of a steroid in <i>Calanus</i>

Ohara, Susumu; Corner, E. D. S.; Kilvington, C. C.

doi:10.1017/s0025315400041254

Cited by 8 publications

(18 citation statements)

References 18 publications

(19 reference statements)

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“…A severe shortage of sterols in the diet might also interfere with steroid metabolism, affecting levels of sex hormones and possibly fecundity (O'Hara et al 1978). Unless the copepod could sequester the ciliatederived triterpenoid alcohol as a substitute for cholester-01, cellular function would ultimately be compromised as cholesterol is depleted during egg production.…”

Section: Discussionmentioning

confidence: 99%

“…As a conservative component of cell membranes in eucaryotes, a minimum concentration of sterols, whether cholesterol or related structures, is required for maintenance of cellular architecture and membrane function (Gennis 1989). A severe shortage of sterols in the diet might also interfere with steroid metabolism, affecting levels of sex hormones and possibly fecundity (O'Hara et al 1978). Unless the copepod could sequester the ciliatederived triterpenoid alcohol as a substitute for cholester-01, cellular function would ultimately be compromised as cholesterol is depleted during egg production.…”

Section: Discussionmentioning

confidence: 99%

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Trophic transfer of fatty acids, sterols, and a triterpenoid alcohol between bacteria, a ciliate, and the copepod Acartia tonsa

1995

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The incorporation of lipids into the copepod Acartia tonsa and its eggs was measured when it was fed either a bacterivorous ciliate (Pleuronema sp.) or a diatom (Thalassiosira weissfogii). Egg production was lo-fold higher on the diatom diet, whereas hatch success of eggs was the same for algal and ciliate diets. Adult copepods fed diatoms contained more total fatty acid and sterols than copepods fed the ciliate diet, and individual lipids reflected the dietary source. Eggs from diatom-fed copepods had fewer fatty acids but more sterols than eggs from copepods on a ciliate diet. Ciliate-fed copepods and their eggs contained significant amounts of odd chain-length and branched fatty acids diagnostic of bacteria. These fatty acids, in particular the iso C,, and C17, were also elevated in ciliates feeding on bacteria in culture, suggesting the direct transfer of bacterial fatty acids from ciliates to copepods and their eggs. We also observed the assimilation of tetrahymanol, a triterpenoid alcohol specific to ciliates, into adults and eggs when copepods were fed a ciliate diet. Tetrahymanol accounted for 6.6 + 1.9% of total neutral lipids in adults and 35.4 + 6.5% in eggs. These results suggest that bacterivorous ciliates may not provide copepods with adequate nutritional requirements for long-term survival, but that lipids unique to bacteria and ciliates can be assimilated by and may provide useful tracers of consumption by copepods.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Trophic transfer of fatty acids, sterols, and a triterpenoid alcohol between bacteria, a ciliate, and the copepod Acartia tonsa

1995

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“…For example, plant sterols are the likely precursors of the steroids recently detected in marine copepods (O'Hara, Corner & Kilvington, 1978;O'Hara, Gaskell & Corner, 1979) and detailed analyses of the various kinds of sterol available in the plant diets are essential to an understanding of steroid biosynthesis in these animals. Detailed lipid data are now available for many unicellular algae, including diatoms, dinoflagellates, the Cyanophyceae and the Chlorophyceae, and often these lipids can be recognized in sediments (e.g.…”

Section: Introductionmentioning

confidence: 99%

Sterol and fatty acid composition of four marine haptophycean algae

et al. 1981

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The lipids of four marine coccolithophorids (class Haptophyceae), Emiliania huxleyi, Hymenomonas carterae, Isochrysis galbana and Crystallolithus hyalinus, were examined by capillary gas chromatography-mass spectrometry. Fatty acids ranged from Ci 4 to C 2 2 and were predominantly of even chain length. The major acids were polyunsaturated C 18 acids, 22:6 and either 14:0 or 16:0. C M fatty acids were of low abundance. Significant amounts of octadecapentaenoic acid (18:5), previously thought to be unique to dinoflagellates, were identified in three of the algae. A small amount of a di-unsaturated C 36 w-alkenoic acid was identified in E. huxleyi, which is the first report of such a long-chain fatty acid in any alga. Traces of wax esters, which are reportedly uncommon inalgae, were found in three of the species. The sterol distributions were very simple, with two or three compounds accounting for > 99 % of the total sterols. In each case, the major component was 24-methylcholesta-5,22E-dien-3/?-ol. H. carterae and C. hyalinus also contained 24-ethylcholesta-5,22E-dien-3/?-ol and significant amounts of cholest-5-en-3/?-ol were found in E. huxleyi and /. galbana. An unusual sterol, 23,24-dimethylcholesta-5,22 E-dien-3/S-ol, was identified in H. carterae. These sterols were mostly non-esterified although small amounts of sterol esters were identified in E. huxleyi. The lipid composition of E. huxleyi is distinctive in that it contains, in addition to the C 36 fatty acid, novel C 37 -C 39 unsaturated ketones and C 31 -C 3S alkenes. Of the other coccolithophorids only /. galbana contained small quantities of one of the C 3l alkenes.

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“…In an earlier study (O'Hara, Corner & Kilvington, 1978) a steroid that binds with mammalian oestradiol-17/? antibody was found in Calanus helgolandicus (Claus) and the related species Calanus finmarchicus Gunnerus.…”

Section: Introductionmentioning

confidence: 99%

“…In addition, the presence in C. finmarchicus of the mammalian sex hormone testosterone (i7/?-hydroxyandrost-4-en-3-one) has been confirmed by GC-MS and the levels of this compound in C. finmarchicus and C. helgolandicus have been determined using radioimmunoassay (RIA). The animals used in the present study were from the same localities as sampled in the earlier work: C. helgolandicus from off Plymouth and C. finmarchicus from Norwegian coastal waters (see O'Hara et al 1978).…”

Section: Introductionmentioning

confidence: 99%

On the nutrition and metabolism of zooplankton XIII. Further studies of steroids inCalanus

1979

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The presence in Calanus finmarchicus of the sex hormone oestradiol-17β has been confirmed by gas chromatography-mass spectrometry (GC-MS) using the trimethylsilyl and heptafluorobutyrate derivatives.Levels of the sex hormone testosterone have been measured by radioimmunoassay in Calanus helgolandicus collected from Plymouth Sound, and in C. finmarchicus captured off the Norwegian coast. Concentrations in C. helgolandicus varied during the year from 150 to 626 fg/animal, accounting for 2.3 to 437 x 10-7% of the lipid content and 10.8 to 64.8 x 10-6%percnt; of the total sterol fraction. The mean level in Stage V C. finmarchicus, captured during spring, was 196 fg/animal.Testosterone was identified in C. finmarchicus by GC-MS of the tert-butyldimethylsilyl derivative.

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On the nutrition and metabolism of zooplankton XII. Measurements by radioimmunoassay of the levels of a steroid in Calanus

Cited by 8 publications

References 18 publications

Trophic transfer of fatty acids, sterols, and a triterpenoid alcohol between bacteria, a ciliate, and the copepod Acartia tonsa

Trophic transfer of fatty acids, sterols, and a triterpenoid alcohol between bacteria, a ciliate, and the copepod Acartia tonsa

Sterol and fatty acid composition of four marine haptophycean algae

On the nutrition and metabolism of zooplankton XIII. Further studies of steroids inCalanus

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