Janice E. Thompson

A chemical defense mechanism for the nudibranch cadlina luteomarginata

Abstract The nudibranch Cadlina luteomarginata from San Diego, California, concentrates selected metabolites from the sponges that constitute its diet. Gut analyses revealed that C. leutomarginata consumes at least ten sponges although Axinella sp. and Myxilla incrustans are most frequently eaten. Field observations and analysis of metabolites suggest that keratose sponges Leiosella idia (= Spongia idia ) and Dysidea amblia are also consumed. Three novel compounds, the furan 20 , the isonitrile 23 and the isothiocyanate 24 were identified by analysis of spectral data. The secondary metabolites of C. leuteomarginata were found only in the dorsum, which is exposed to potential predators. Five metabolites of C. luteomarginata were screened for antifeedant activity against fish and all showed some activity at 10–100 μ/mg in food pellets.

Predicted and Measured Resting Metabolic Rate of Male and Female Endurance Athletes

Abstract Objective To measure the resting metabolic rate (RMR) of a group of endurance-trained male and female athletes and to compare it with values predicted using published equations. Design RMR was measured twice: 1 week apart for the men and approximately 1 month apart for the women. RMR was predicted using equations of Harris and Benedict, Owen et al, Mifflin et al, and Cunningham. Subjects/Setting Subjects were 37 trained endurance athletes (24 men, 13 women) who had participated in studies previously completed in our laboratory. Main outcome measures The primary outcome measure was the comparison of predicted RMR with measured RMR. An exploratory procedure for the determination of predictive variables in these athletes was also performed. Statistical analyses performed The Root Mean Squared Prediction Error method was used to compare predicted RMR with measured RMR. The maximum R 2 procedure method was used to determine the best possible combination of four variables that explained the largest amount of variance in RMR. Results The Cunningham equation was found to predict measured RMR most accurately (within 158 kcal/d for men and 103 kcal/d for women). Fat-free mass was the best predictor of RMR in men, whereas energy intake was the best predictor in women. Applications/conclusions The Cunningham equation provides an accurate estimate of RMR when determining energy needs of highly active people. Equations specific to athletes need to be developed. Factors in addition to body weight, height, and age should be investigated as possible predictor variables in athletes. J Am Diet Assoc. 1996; 96:30-34.

Environmentally induced variation in diterpene composition of the marine sponge Rhopaloeides odorabile

Abstract A common Great Barrier Reef sponge, previously attributed to the genus Spongia , is described as new and placed in a new genus Rhopaloeides . This genus includes Spongiidae otherwise identical to Spongia in which the cored primary fibres form simple fascicles. The genus is also characterized by its form (massive, thick broad-based lamellae or multiple fused thick clubs). The chemistry is distinctive, characterised by possession of a rare group of C 20 diterpene furanodiols, triols and their peracetates. Considerable variation in the total yield and composition of the diterpenes for different collections of R. odorabile was confusing and led to a suggestion that more than one species was represented. Field experiments in which fragments of one individual sponge were transplanted to different conditions of illumination and depth, demonstrate that the chemical variability reflects the range of environmental conditions under which R. odorabile lives rather than any genetic differences.

Biosynthetic studies of marine lipids 12.: Biosynthesis in marine sponges of sterois possessing the δ5,7-nucleus typical of fungi and the 24-alkyl side chain characteristic of plants

Abstract The biosynthesis of sterols with structural patterns common to plant and yeast sterols was studied by incorporation of eleven radiolabeled sterol precursors and mevalonate. The capability of sponges to convert Δ 5 - into Δ 5,7 -sterols, which was as efficient as the conversion of Δ 7 - into Δ 5,7 -sterols, was demonstrated by double labelling experiments. By examining epimeric pairs, stereospecific conversion of codisterol and clerosterol into the corresponding 7-dehydrosterols was established. 24β-24-Alkyl sterols with homo-conjugated 22,25-diene side chains are proposed as actual intermediates in the formation of Δ 22 -24β-alkylsterols. An alternative pathway via oxidation at C-22 or C-23 with subsequent dehydration of an intermediate 22(R or S)- or C-23(R or S)-hydroxysterol is probably not operative due to lack of incorporation of any of the tritium labeled alcohols. These biosynthetic features, though unexpected for animals, nevertheless are attributed to the sponge because of the absence of symbiotic fungi and algae as shown by electron microscopy.

Fatty acids as biological markers for bacterial symbionts in sponges

Analyses of fatty acids with carbon numbers between C12 and C22 are reported for five Great Barrier Reef sponges. These analyses indicate that phototrophic cyanobacterial symbionts (blue-green algae) present in three of the sponges are chemically distinct, whereas the other two sponges do not contain cyanobacterial symbionts. All the sponges contain other, nonphototrophic bacteria. The fatty acid analyses indicate that the nonphototrophic bacterial populations present in the different sponges are distinct in both their chemical compositions and their abundances. Nonphototrophic bacteria are estimated to account for between 60 and 350 μg/g (extractable fatty acids:tissue wet weight), whereas cyanobacteria account for between 10 and 910 μg/g. One sponge (Pseudaxinyssa sp.) contains a relatively large amount of the isoprenoid acid, 4,8,12-trimethyltridecanoic acid; this acid is presumed to be derived from phytol, a degradation product of chlorophyll. This sponge also contains relatively large amounts of the nonmethylene interrupted fatty acid, octadeca-5,9-dienoic acid. Analyses of interior and cyanobacteria-rich surface tissues of this sponge indicate that these two acids are probably not associated with the symbiotic cyanobacteria.

Biosynthetic studies of marine lipids—3 : Experimental demonstration of the course of side chain extension in marine sterols

Abstract The Pacific sponge Aplysina fistularis was fed cholesterol-[4- 14 C],(24 R )-methyl-25-dehydrocholesterol-[26- 14 C] (epicodisterol[26- 14 C]), (24 S )-methyl-25-dehydrocholesterol-[26- 14 C] (codisterol-[26- 14 C]), and 24-methylenecholesterol-[28- 14 C]. Only epicodisterol, which has the same stereochemistry at C-24 as (24 R ,25 S )-24,26-dimethylcholesterol (aplysterol), was converted with high efficiency into (24 R )-24,27-dimethyl-25-dehydrocholesterol (25-dehydroaplysterol). Further side chain extension [to E -(24 R )-24,26,27-trimethyl-25-dehydrocholesterol (verongulasterol)] could also be demonstrated.

TERPENES IN SPONGE CELL-MEMBRANES - CELL-SEPARATION AND MEMBRANE FRACTIONATION STUDIES WITH THE TROPICAL MARINE SPONGE AMPHIMEDON-SP

The differing sponge and symbiotic microbial cell types in the tropical marine spongeAmphimedon sp. were fractionated according to density, investigated by electron microscopy, and analyzed by high-performance liquid chromatography and nuclear magnetic resonance for the presence of the terpene metabolite diisocyanoadociane (1) and Δ5,7-sterols (2–7). A sample of whole sponge was dissected into superficial ectosome and deeper choanosome. The superficial tissue was found to be enriched in sterol relative to choanosome; however, extracts from both tissues contained terpene. Dissociation of whole sponge followed by Ficoll density gradient fractionation showed that there are two chemically distinct types of sponge cells inAmphimedon sp.—small non-nucleolated cells of low density contain terpene 1 together with sterols, while larger nucleolated cells contain significant levels of terpene, but only traces of sterol. Membrane fractionation studies were undertaken to establish whether the terpene components were located specifically in the cell membranes of these two cell types. A membrane vesicle pellet spun down at 100,000×g from small sponge cells contained sterols, but only traces of terpene, whereas the membrane vesicle preparation from heavier cells contained both terpenes and sterols. Subsequently, the presence of terpenes together with sterols was demonstrated in a membrane vesicle preparation of purity >90% prepared from bacteria-free sponge cells. These results provide the first experimental evidence that terpenes are associated with sponge cell membranes, where they may function as structural components.

Cell membrane localization of long chain C24-C30 fatty acids in two marine demosponges.

Subcellular fractionation by differential centrifugation was performed on two previously unstudied marine sponges (Reniera sp. andPseudaxinyssa sp.) that represent both major subclasses of the Demospongiae. Long chain fatty acids (LCFA) with 24–30 carbon units were found as major constituents of cell membrane isolates of both sponges. Most LCFA were polyunsaturated and were constituents of the phospholipids, which are typical membrane lipids, and in particular the amino-phospholipids. The LCFA composition of phospholipids from whole sponge tissue was shown to provide a reliable indication of the LCFA composition of cell membrane phospholipids in the sponges studied. An unusual triply branched C16 isoprenoid fatty acid, 4,8,12-trimethyltridecanoic acid, also was identified as a cell membrane acid in the spongePseudaxinyssa sp.

The distribution of lipids and sterols in cell types from the marine spongePseudaxinyssa sp

The spongePseudaxinyssa sp., unique in sterol and fatty acid composition, was cellularly dissected into fractions enriched in each of the major cell types present in the sponge: microbial symbionts (cyanobacteria), small sponge cells (pinacocytes and choanocytes), and large sponge cells (archeocytes and cyanophytes). Three phototrophic microbial symbionts were also isolated from the cell fractions and grown in culture. An unsymmetrical distribution of fatty acids and sterols was observed for the sponge cells: small cells contained larger quantities of long chain fatty acids (> C24) and smaller quantities of sterols than were present in the larger sponge cells. Moreover, the rare sterols 24-isopropylcholesterol predominated in the smaller sponge cells, whereas its 22-dehydro analog predominated in the larger sponge cells. Long chain fatty acids and sterols were not detected in the cultured microbial symbionts. This constitutes the first report of lipid variability according to cell type for this most primitive group of Metazoa.

Biosynthetic studes of marine lipids 7 : Experimental demonstration of a double alkylation at c-28 in the biosynthesis of 24-isopropylcholesterols in a sponge

Abstract The biosynthesis of 24-isopropyl sterols comprising 99% of the sterols of the Great Barrier Reef sponge Pseudaxinyssa sp. was studied. The major biosynthetic pathway was established by incorporation of 24-methylenecholesterol-[28-14C], fucosterol-[22-T], isofucosterol-(22-T], (24R)-24-isopropenylcholesterol-(29-14C], (24S)-24-isopropenylcholesterol-[29-14C], DL-mevalonate-(2-14C] and L-methionine-[methyl-14C]. Very efficient side chain branching through double alkylation at C28 was demonstrated in contrast to relatively poor de novo biosynthesis. A stereoselective mode for hydrogen migration is observed and a regioselective mode is proposed for this migration.