(3R(*),5S (*),6R (*))-3,5-dimethyl-6-(methylethyl)-3,4,5,6-tetrahydropyran-2-one, a third sex pheromone component forMacrocentrus grandii (goidanich) (Hymenoptera: Braconidae) and evidence for its utility at eclosion

The compound (3R(*),5S(*),6R(*))-3,5-dimethyl-6-(methylethyl)-3, 4,5,6-tetrahydropyran-2-one was identified as a sex pheromone component ofM. grandii. Laboratory and field bioassays demonstrated that it elicits flight initiation, upwind anemotaxis, and casting in male wasps. The compound acts synergistically with (Z)-4-tridecenal, a previously identified sex pheromone component of femaleM. grandii, to increase male response to the aldehyde component. The source of the lactone was determined to be the mandibular glands of male and female wasps. At eclosion a majority of male-female and female-only cocoon masses released the lactone and attracted male wasps. Male-only cocoon masses were not attractive at eclosion and the lactone component was either not released or released at below-threshold concentration. Mating was observed to occur following eclosion in laboratory and field studies.

Analysis of protein expression patterns in Barrett's esophagus using MALDI mass spectrometry, in search of malignancy biomarkers

In order to detect early changes of malignant degeneration in Barrett's esophagus (BE), and to reduce the cost of surveillance, molecular biomarkers of early malignancy have been sought, with limited success, using genomic and immunohistochemical tools. We postulate that direct analysis of epithelial proteins using mass spectrometry will provide protein profiles capable of identifying patients at high risk of developing malignancy. Our aim is to find transitional protein signals that show a cancer profile within histologically benign BE, which can be used as indicators of early malignant change. Fourteen fresh-frozen, resected esophageal cancer specimens were analyzed using laser capture microdissection and matrix-assisted laser desorption/ionization mass spectrometry. Samples of squamous epithelium, and both benign and malignant Barrett's epithelium, were compared for differences in protein expression. Reliable differentiation of squamous and Barrett's epithelium was demonstrated. A comparison of benign and malignant Barrett's epithelium identified a number of cancer-specific protein peaks that were deletion or expression variations from benign epithelium. In four instances the proteins (7350, 8446, 10850, and 14693) appeared to be early malignant changes in histologically benign BE. Mass spectrometry performed upon fresh-frozen Barrett's epithelium, obtained by laser-capture microdissection, displays reproducible, tissue-specific, protein profiles. Distinct differences are demonstrated between benign and malignant epithelium, some of which appear to be candidate biomarkers of early malignant change. This technique reliably displays cellular protein expression in esophageal epithelium and deserves further study as a tool to identify early malignant degeneration in BE.

Characterization of the linkage between the type III capsular polysaccharide and the bacterial cell wall of group B Streptococcus

The capsular polysaccharide of group B Streptococcus is a key virulence factor and an important target for protective immune responses. Until now, the nature of the attachment between the capsular polysaccharide and the bacterial cell has been poorly defined. We isolated insoluble cell wall fragments from lysates of type III group B Streptococcus and showed that the complexes contained both capsular polysaccharide and group B carbohydrate covalently bound to peptidoglycan. Treatment with the endo-N-acetylmuramidase mutanolysin released soluble complexes of capsular polysaccharide linked to group B carbohydrate by peptidoglycan fragments. Capsular polysaccharide could be enzymatically cleaved from group B carbohydrate by treatment of the soluble complexes with beta-N-acetylglucosaminidase, which catalyzes hydrolysis of the beta-D-GlcNAc(1-->4)beta-D-MurNAc subunit produced by mutanolysin digestion of peptidoglycan. Evidence from gas chromatography/mass spectrometry and (31)P NMR analysis of the separated polysaccharides supports a model of the group B Streptococcus cell surface in which the group B carbohydrate and the capsular polysaccharide are independently linked to the glycan backbone of cell wall peptidoglycan; group B carbohydrate is linked to N-acetylmuramic acid, and capsular polysaccharide is linked via a phosphodiester bond and an oligosaccharide linker to N-acetylglucosamine.

Analysis of hydroxy and keto cholesterols in oxidized brain synaptosomes

A rapid method for the simultaneous determination of cholesterol and its oxidation products as well as alpha-to-copherol and tocopherolquinone in brain subcellular fractions is described. The samples are saponified and extracted with hexane. It is not necessary to remove cholesterol in the sample before analyzing for oxysterols. The hexane extract can be used for the assay of cholesterol compounds by capillary gas chromatography and tocopherol compounds by liquid chromatography using a procedure reported previously. Oxidation of synaptosomes by a mixture of Fe2+ plus ascorbate resulted in the production of 7-keto-, 7 alpha-hydroxy-, 7 beta-hydroxy-, and 5 alpha, 6 alpha-epoxycholesterols. The identities of these products were confirmed with gas chromatography/mass spectrometry. Cholesterol oxidase treatment did not result in the formation of any of the above compounds. Thus the types and amounts of the products of oxidation of cholesterol were dependent upon the oxidizing agent. Extraction of the oxysterols under milder conditions without saponification using sodium dodecyl sulfate cannot be used since such treatment results in low recovery of oxysterols. Oxidation of synaptosomes by low concentrations of ferrous iron and ascorbate resulted in (i) low levels of oxidation of cholesterol which could be followed by estimating the production of oxysterols and (ii) oxidation of a substantial percentage of alpha-tocopherol. The proposed procedure will be useful in monitoring the oxidation of small quantities of membrane cholesterol in vitro.

Identification of Pea Gibberellins by Studying [C]GA(12)-Aldehyde Metabolism

Experiments were designed to test the hypothesis that the labeled products recovered from plant tissue incubated with [(14)C]GA(12)-7-aldehyde ([(14)C]GA(12)ald) would serve as appropriate [(14)C]markers for the recovery of naturally-occurring gibberellins (GAs). The [(14)C]GA(12)ald (about 200 millicuries per millimole) was synthesized from pumpkin endosperm using [4,5-(14)C]mevalonic acid. It was added to the adaxial surface of isolated pea cotyledons at 22 days after flowering. Products recovered after 0.5 and 4.0 hour incubations yielded four major peaks which were separated by high performance liquid chromatography (HPLC). These products were purified by multiple-column HPLC using on-line radioactivity detection. They were then added as [(14)C]markers to two unlabeled pea extracts. In general, preparative HPLC followed by further HPLC purification resulted in a single UV-absorbing peak co-eluting with each [(14)C]marker. These [(14)C] and UV-absorbing peaks were shown to contain GA(53), GA(44), GA(20), GA(19), and GA(17) by GC-MS. The finding of GA(53) is novel; all others have previously been found in pea. Endogenous GAs of pea were thus readily detected using [(14)C]GA(12)ald metabolites as [(14)C]markers to recover naturally occurring GAs suggesting that the method may be applicable in detecting naturally occurring GAs in other species.

Identification of a dihydrophaseic Acid aldopyranoside from soybean tissue

A previously unidentified abscisic acid metabolite has been isolated and characterized. (+/-)-[2-(14)C]Abscisic acid was incubated in intact soybean leaves and pods; the radiolabeled metabolite was purified by high performance liquid chromatography with on-line scintillation spectrometry detection. Gas chromatography-mass spectrometry was used to obtain spectra of the acetylated and methyl esterified derivatives. The data were consistent with a proposed dihydrophaseic acid-aldopyranoside identity. Conjugation through the 4'-hydroxyl of dihydrophaseic acid is suggested.

18O-Labeling of guanosine monophosphate upon hydrolysis of cyclic guanosine 3':5'-monophosphate by phosphodiesterase

The hydrolysis of cGMP by phosphodiesterase was conducted in [18O]water to determine the site of bond cleavage and the stoichiometry of 18O incorporation into 5'-GMP. Three different forms of phosphodiesterase including a calmodulin-calcium-dependent enzyme in its basal and activated states were examined. The hydrolysis of cGMP catalyzed by each of the forms of phosphodiesterase proceeded with incorporation of 1 18O atom recoverable in the phosphate moiety of each molecule of 5'-GMP generated. No molecular species of phosphate deriving from the 5'-GMP generated containing two or three 18O were detectable. These results indicate that the phosphodiesterase-catalyzed hydrolysis of cGMP proceeds by nucleophilic substitution at phosphorus resulting in P-O bond cleavage. The stoichiometry of 18O incorporation indicates that the reaction proceeds without phosphate-water oxygen exchange when the hydrolytic reaction is catalyzed by diverse forms of phosphodiesterase in the basal or activated state. These considerations of the phosphodiesterase reaction help to establish the validity of monitoring the rate of enzyme-catalyzed hydrolysis of cGMP as a function of the rate of 18O-labeling of the phosphate of 5'-GMP when the reaction proceeds in a medium of predetermined 18O enrichment.

Effects of different fuchsin analogs on the Feulgen reaction

The Feulgen reaction is used for cytophotometric quantitation of nuclear DNA. Schiff's reagents used in the Feulgen reaction usually are prepared from basic fuchsin, a variable mixture of four triaminotriphenylmethane analogs. The effect of the several fuchsin analogs on the quality of Schiff's staining of hydrolyzed DNA is not known. In this investigation Schiff's reagents prepared from relatively pure fuchsin analogs were used to determine whether different fuchsin analogs affect the absorbance of the Schiff's reagent-DNA complexes formed in solution. It has been determined that the complex formed by pararosaniline-Schiff's reagent and hydrolyzed DNA exhibits lower absorption than do corresponding complexes formed by Schiff's reagents prepared from magenta II or from new fuchsin.

Identification of 15-keto-9, 11-peroxidoprosta-5, 13- dienoic acid as a hematin-catalyzed decomposition product of 15-hydroperoxy-9, 11-peroxidoprosta-5, 13-dienoic acid

A labile prostaglandin was isolated as one of the products generated from [1-14C] eicosatetraenoic acid incubated with sheep vesicular gland microsomes. The eicosatetraenoic acid metabolite amounted to ca. 16% of the total radiolabeled products. Formation of this new prostaglandin was prevented when heat-denatured microsomes were employed or when incubation mixtures were supplemented with indomethacin or phenol. However, incubation of prostaglandin G2 (PGG2) with hematin in the presence or absence of catalytically active or heat-inactivated microsomes led to production of approximately the same quantity of the new prostaglandin. These results indicated that the new prostaglandin can be formed nonenzymically. The new prostaglandin was conclusively identified by gas liquid chromatography-mass spectrometry analysis as 15-keto-9,11-peroxidoprosta-5,13-dienoic acid (15-keto-PGG2) after chemical conversion to known prostaglandins. The effects of 15-keto-PGG2 and PGG2 were similar on canine lateral saphenous vein; both promoted contraction followed by prolonged relaxation, but 15-keto-PGG2 appeared to be 1/50 as potent as PGG2.

Ferrous iron mediated oxidation of arachidonic acid: studies employing nitroblue tetrazolium (NBT)

The oxidation of arachidonic acid by ferrous sulfate provides a useful model to study the role of iron in lipid oxidation reactions. We have employed nitroblue tetrazolium (NBT) in the present investigation to evaluate the mechanism of this reaction. In the presence of arachidonic acid, Fe +++, and O2, the yellow dye NBT was rapidly reduced to the blue form, NBTH2. The molar ratio of arachidonic acid to Fe++ in this rapid reaction was 1:1, showing an interaction of one fatty acid molecule per iron molecule. Approximately one molecule of NBT was reduced per four molecules of arachidonic acid and Fe++. Reduction of NBT was accompanied by oxidation of Fe++ to Fe+++, suggesting the transfer of four electrons from the Fe++ to NBT to reduce the dye. Arachidonic acid was found to be unchanged when extracted at the end of the reaction, indicating formation of a complex that could dissociate leaving intact arachidonic acid. Evidence for the presence of such a complex which slowly dissociates during the reaction was obtained after longer incubations with small amounts of arachidonic acid. NBT reduction was not inhibited by agents which hydrolyze superoxide, by catalase or by agents which trap hydroxy radicals. We, therefore, propose a model in which NBT traps a radical generated on the arachidonic acid molecule. The proposed model suggests mechanisms for other fatty acid oxidation reactions such as prostaglandin and hydroperoxy fatty acid synthesis.

The occurrence and distribution of furan fatty acids in spawning male freshwater fish

Furan fatty acids (F acids) have been found in the livers and/or testes of 20 species, representing 9 families, of male freshwater fish. In 9 species they are major components of the lipids while in the remaining 11 species they occur to a much lesser extent. The F acids in some species reach a maximum concentation in the testes lipids, and minimum liver lipid concentration, at spawning. In all species in the testes, the F acids are confined almost exclusively to the triglyceride fraction while, in the liver lipids, they are found, in order of decreasing concentration, in the cholesteryl esters, the triglycerides, and the phospholipids. In the lipids of many individuals F6, 12,15-epoxy-13,14-dimethyleicosa-12,14-dienoic acid, is the major fatty acid present. It is presumed that these acids perform some as yet unidentified metabolic function. Isolation technology and identification of F acids by a specific thin layer chromatographic spray reagent are discussed.

Metabolism of N-ethyl-3-piperidyl benzilate in rats

The metabolic fate of N-ethyl-3-piperidyl benzilate (I) and its potential metabolites 3-piperidyl benzilate (II), N-ethyl-3-hydroxypiperidine (III), and 3-hydroxypiperidine (IV) was studied. Incubation of I with rat liver homogenates resulted in the formation of II and III. Only a trace of unchanged drug appeared in urine after intraperitoneal injection of I. Approximately 9% of the injected dose of I was excreted in urine as III and 2% in the form of metabolites that produced III after acid hydrolysis. After intraperitoneal injection of II in rats, 18% of the dose was excreted in urine as IV. Approximately 26% of the injected dose of III was present in urine as the unchanged drug, and 63% of the dose was excreted in the urine in the form of conjugates that produced III on acid hydrolysis. Urine of rats injected with IV contained approximately 50% of the injected dose as the unchanged drug and 50% of the dose in the form of a conjugate that produced IV on acid hydrolysis. The identity of the metabolites in extracts from urine was established by GLC-mass spectrometry. It is concluded that hydrolysis was one metabolic pathway for I and II. The major routes of elimination of these compounds are not yet known and may include excretion in feces or metabolic transformations resulting in the degradation of the piperidine ring.

Cyclic AMP and platelet prostaglandin synthesis

The present study has investigated the influence of agents which elevate intracellular levels of endogenous platelet adenosine 3'5'-cyclic monophosphate (cyclic AMP), and the effect of the exogenous cyclic AMP analog, dibutyryl cyclic AMP, on the conversion of 14C-arachidonic acid by washed platelets. Prostaglandin E1 (PGE1), PGE1 with theophylline, or dibutyryl cyclic AMP incubated with washed platelets prevented arachidonic acid induced platelet aggregation, but had no effect on the conversion of arachidonic acid to 12L-hydroxy-5,8,10, 14-eicosatetraenoic acid (HETE), 12L-hydroxy-5,8,10 heptadecatrienoic acid (HHT), or thromboxane B2. Ultrastructural studies of the platelet response revealed that agents acting directly or indirectly to increase the level of cyclic AMP inhibited the action of arachidonic acid on washed platelets and prevented internal platelet contraction as well as aggregation. The influence of PGE1 with theophylline, and dibutyryl cyclic AMP on the thrombin induced release of 14C-arachidonic acid from platelet membrane phospholipids was also investigated. These agents were found to be potent inhibitors of the thrombin stimulated release of arachidonic acid from platelet phospholipids, due most likely to an inhibition of platelet phospholipase A activity. The results show that dibutyryl cyclic AMP and agents which elevate intracellular cyclic AMP levels act to inhibit platelet activation at two steps 1) internal contraction and 2) release of arachidonic acid from platelet phospholipids.

Furanoid fatty acids from fish lipids

Fatty acids, recently reported as constituents of certain fish lipids, were identified to be derivatives of furan (furanoid fish fatty acids). 12,15-Epoxy-13,14-dimethyleicosa-12,14-dienoic acid is predominant among the furan acids and is associated with bis-homologs in regard to chain length. Monomethyl acids, such as 12,15-epoxy-13-methyleicosa-12,14-dienoic, are present in appreciable amounts. The structures were concluded from oxidative degradations, from mass spectrometry of methyl esters of the novel acids and fatty acids derived from them by opening the ring, and from nuclear magnetic resonance, infrared, and Raman spectra. The results from chemical procedures and from spectrometric methods were in agreement with those obtained with authentic methyl 9,12-epoxyoctadeca-9,11-dienoate. The number of substituents at the furan ring greatly influences hydrogenation, hydrogenolysis, and hydrolysis reactions of the ring.