The occurrence of ecdysteroids in the cestode, Moniezia expansa.

The occurrence of free ecdysteroids in the sheep cestode, Moniezia expansa, was demonstrated. Significant amounts of conjugated ecdysteroids were not detected. Characterization of the free hormones by high-performance liquid chromatography monitoring fractions by radioimmunoassay, and by gas chromatography/mass spectrometry (selected ion monitoring) indicated the presence of ecdysone, 20-hydroxyecdysone and 20,26-dihydroxyecdysone. Analysis of the ecdysteroids by radioimmunoassay in segments along part of the strobila indicated that the anterior parts contained the greatest amount of hormone. GC/MS (SIM) analysis of the hormones in a strobilar segment containing the most mature proglottids suggested the presence of several ecdysteroid metabolites.

Ecdysteroids in adults of the nematode, Dirofilaria immitis.

Adult males and females of the dog heartworm, Dirofilaria immitis, were extracted separately and, following separation of the free and conjugated ecdysteroid fractions, the conjugates were hydrolysed enzymically. Both the ecdysteroids released by hydrolysis of the conjugates and the free hormones were further purified and analysed by a combination of radioimmunoassay, thin-layer chromatography and high-performance liquid chromatography monitoring fractions by radioimmunoassay, and by gas-liquid chromatography/mass spectrometry (selected ion monitoring). Both males and females contained free and conjugated ecdysteroids. Evidence was obtained for the presence of ecdysone, 20-hydroxyecdysone, 20,26-dihydroxyecdysone and possibly ponasterone A. The possible parallel between ecdysteroid endocrinology in nematodes and insects is discussed.

Identification of the 22-phosphate esters of ecdysone, 2-deoxyecdysone, 20-hydroxyecdysone and 2-deoxy-20-hydroxyecdysone from newly laid eggs of the desert locust, Schistocerca gregaria.

The four major ecdysteroid (insect moulting hormone) conjugates present in the newly laid eggs of the desert locust, Schistocera gregaria, have been purified by reversed-phase and anion-exchange high-performance liquid chromatography. The steroid moieties were identified as ecdysone, 2-deoxyecdysone, 20-hydroxyecdysone and 2-deoxy-20-hydroxyecdysone. Phosphate analysis of acid-hydrolysed samples showed a steroid:phosphate ratio of approx. 1:1 for all four compounds. The intact conjugates were identified as ecdysone 22-phosphate, 2-deoxyecdysone 22-phosphate, 20-hydroxyecdysone 22-phosphate and 2-deoxy-20-hydroxyecdysone 22-phosphate by fast atom bombardment mass spectrometry and 1H, 13C and 31P n.m.r. The significance of ecdysteroid phosphates as a source of free hormone during embryogenesis is discussed.

Formation of the A/B cis ring junction of ecdysteroids in the locust, Schistocerca gregaria.

1. The mechanism of formation of the A/B cis ring junction of ecdysteroids in the locust Schistocerca gregaria, was investigated by incorporation of [4-14C,3 alpha-3H], [4-14C,4 alpha-3H] and [4-14C,4 beta-3H]cholesterol into 20-hydroxyecdysone in fifth-instar larvae and into ecdysteroid conjugates in ovaries of maturing adult females. 2. In both systems there was retention of the 4 alpha-3H atom in the ecdysteroid and elimination of the 3 alpha- and 4 beta-3H atoms. 3. The 3H retained in the ecdysone formed from [4 alpha-3H]cholesterol in the ovarian system was probably located at C-4. The results are interpreted by postulating the involvement of a 3-oxo-delta 4 intermediate in ecdysteroid biosynthesis in insects.

Mechanism of formation of the A/B cis ring junction of ecdysteroids in Polypodium vulgare.

1. The fates of the alpha-, 4 alpha- and 4 beta-hydrogen atoms of cholesterol during formation of the A/B cis ring junction of ecdysteroids was investigated by administration of [4-14C, 3 alpha-3H], [4-14C, 4 alpha-3H]- and [4-14C, 4 beta-3H]cholesterol species to the fern, Polypodium vulgare, and isolation of the 20-hydroxyecdysone formed in each case. 2. The 3H was retained in the ecdysteroid formed from each substrate. 3. Location of the 3H in the 20-hydroxyecdysone indicated that migration of 3H from the 3 alpha- and 4 beta-positions to C-4 and C-5, respectively, had occurred, whereas the 4 alpha-3H atom was retained at C-4. 4. A possible mechanism for the formation of the A/B cis ring junction of ecdysteroids in P. vulgare is presented.

Mechanism of dealkylation of clionasterol in the insect Tenebrio molitor.

1. 25-3H- and 26-14C-labelled (24S)-24-ethylcholest-5-en-3beta-ol (clionasterol) were synthesized from (24S)-24-ethylcholesta-5,25-dien-3beta-ol. 2. These labelled substrates were mixed and administered, together with the hypocholesterolemic agent, triparanol citrate, to Tenebrio molitor larvae. 3. The 3H label from the clionasterol substrate was retained in both the desmosterol and the cholesterol isolated from the larvae. 4. Location of this 3H label in the desmosterol showed that dealkylation of the clionasterol involved 3H migration from C-25 to C-24. A possible mechanism for dealkylation is presented.

Photosynthetic unit size, carotenoids, and chlorophyll-protein composition of Prochloron sp., a prokaryotic green alga.

Six samples of the prokaryotic, unicellular algae Prochloron sp., which occur in association with didemnid ascidians, were collected from various localities in the tropical Pacific Ocean, and their pigments and chlorophyll-protein complexes were identified and characterized. No phycobilin pigments were detected in any of the species. Chlorophylls a and b were present in ratios of a/b = 4.4-6.9. The major carotenoids were beta-carotene (70%) and zeaxanthin (20%). Minor carotenoids of one isolate were identified as echinenone, cryptoxanthin, isocryptoxanthin, mutachrome, and trihydroxy-beta-carotene; no epsilon-ring carotenoids were found in any sample. Except for the absence of glycosidic carotenoids, the overall pigment composition is typical of cyanobacteria. A chlorophyll a/b-protein complex was present in Prochloron; it was electrophoretically and spectrally indistinguishable from the light-harvesting chlorophyll a/b-protein of higher plants and green algae. It accounted for 26% (compared to approximately 50% in green plants) of the total chlorophyll; 17% was associated with a P700-chlorophyll a-protein. The photosynthetic unit size of 240 +/- 10 chlorophylls per P700 in Prochloron was about half that of eukaryotic green plants. A model is proposed for the in vivo organization of chlorophyll in Prochloron.

Stereochemistry of olefinic bond formation in defensive steroids of Acilius sulcatus (Dytiscidae).

The defensive secretion of Acilius sulcatus contains a number of pregnane derivates: cortexone, 20alpha-hydroxy-4-pregnen-3-one, together with the unusual delta4,6 dienes, 6,7-dehydrocortexone, 20alpha-hydroxy-4,6-pregnadien-3-one and 4,6-pregnadien-3,20-dione. The synthesis of all these steroids except cortexone is described. Complete separation of the steroids of Acilius can be achieved by high-performance liquid chromatography on the reversed-phase column system. During biosynthesis of the Acilius steroids from cholesterol, introduction of the delta4 and delta6 bonds involves elimination of the 4beta and 7beta hydrogens, respectively. Possible mechanisms of formation of the delta4,6 steroids are discussed.

Carotenoid biosynthesis in Rhodomicrobium vannielii. Experiments with nicotine and 2-(4-chlorophenylthio)triethylammonium chloride (CPTA).

Nicotine and 2-(4-chlorophenylthio)triethylammonium chloride (CPTA) each inhibit production of the normal carotenoids of Rhodomicrobium vannielii (Rhodospirillaceae), especially rhodopin, beta-carotene and spirillixanthin, and cause the accumulation of lycopene. The inhibition of hydration of the C-1,2 double bond as well as cyclization is in agreement with proposals that these two reactions involve similar mechanisms. After removal of nicotine, cells reincubated in buffer solution or in the presence of diphenylamine convert accumulated lycopene into rhodopin. Under other conditions rhodopis is synthesized, on removal of nicotine, not from accumulated lycopene but from early precursors. The pathway of rhodopin and spirilloxanthin biosynthesis in Rm. vannielii is discussed briefly, and the possible involvement of enzyme aggregates in carotenoid biosynthesis is considered.

The carotenoids of Flavobacterium strain R1560.

The main carotenoid of Flavobacterium strain R1560 has been identified as (3R,3'R)-zeaxanthin. Also present were small amounts of 15-cis-phytoene, phytofluene, "zeta-carotene" (7,8,7',8'-tetrahydro-psi, psi-carotene plus 7,8,11,12-tetrahydro-psi, psi-carotene), neurosporene, lycopene, beta-zeacarotene, gamma-carotene, beta-carotene, beta-cryptoxanthin, rubixanthin, 3-hydroxy-beta-zeacarotene and several apo-carotenals. Zeaxanthin production was inhibited by nicotine (10 mM), and lycopene and rubixanthin accumulated. The biosynthesis of zeaxanthin is discussed in terms of pathways and also of "half-molecule" reaction sequences. The presence of zeaxanthin may be a characteristic of a group of Flavobacterium species, and may thus be useful in the taxonomic classification of these organisms.

Separation of C27, C28 and C29 sterols by reversed-phase high-performance liquid chromatography on small particles.

The application of reversed-phase high-performance liquid chromatography to the analytical- and preparative-scale separation of sterols has been evaluated. The capacity factors, k', for a number of compounds chromatographed on a muBondapak C18 (LESS THAN 10 MUM) COLUMN ARE PRESENTED. C27, C28 and C29 sterols and also sterols differing in degree of unsaturation could be readily separated as their acetates in this system. The present reversed-phase chromatographic method is apparently not as selective as silver nitrate-silica gel thin-layer chromatography for the position of unsaturation in the sterol molecule.