Electrophoretic studies on the Anisakis simplex complex (Ascaridida:Anisakidae) from the Mediterranean and North-East Atlantic

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and 1986. Electrophoretic studies on the Anisakis simplex complex (Ascaridida: Anisakidae) from the Mediterranean and North-East Atlantic. International Journal for Parasitology 16: 633–640. The genetic variation of the sibling species Anisakis simplex A and A. simplex B was investigated by electrophoretic analysis of 22 gene-enzyme systems. The two species are reproductively isolated and no gene flow takes place between them. Three loci, Sod, Adk-2 and Lap-1, show distinct alleles in A. simplex A and A. simplex B, allowing their reliable identification both at the larval and adult stages. A fourth locus, Got, appears to be diagnostic at the 95% level. The value of Nei's genetic distance found between A. simplex A and A. simplex B is 0.28. Parameters of genetic variability (He, P, A) are given for both species. The geographic distribution of A. simplex A and A. simplex B appears to be mainly Mediterranean for the former, and mainly North Atlantic for the latter. Several paratenic hosts (fish and squid) and one cetacean definitive host are identified for each of the two species. The names A. pegreffii and A. simplex are tentatively proposed for A. simplex A and A. simplex B respectively.     

The surface topography and ultrastructure of the tegument and haptor of Pricea multae (Monogenea)

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and 1986. The surface topography and ultrastructure of the tegument and haptor of Pricea multae (Monogenea). International Journal for Parasitology 16: 581–589. Pricea multae is a gill parasite of Scomberomorus spp. In the present study, the surface specialization and ultrastructure of the tegument and haptor were examined in detail. The buccal cavity and the preoral pit bear uniciliated sensory endings. The genital atrium opens on the ventral surface whereas the vaginal pore opens on the dorsal surface of the anterior region. The general body surface is elevated by pits and folds together with papillae-like uniciliated sensory endings. Microvilli are uncommon.

The syncytium of the tegument is bounded by apical and basal plasma membranes. Some electron-dense granules and electron-lucent vesicles were observed exocytosing at the apical surface. The tegumental perikarya lie amongst the muscle blocks underneath the basal lamina. The body wall muscle fibres are non-striated consisting of thick and thin myofilaments. Each muscle fibre is limited by a sarcolemma and separated from neighbouring fibres by interstitial material.

The haptor possesses two rows of pincer-type clamps. The clamps may be withdrawn by muscles into cavity-like depressions. Electron-dense fibrils are embedded within the clamp sclerite matrix. The intrinsic muscles of the clamp include radial muscles enclosed within the basal lamina. The muscle fibres enclosed within the basal lamina of the clamp appear to differ from the body wall muscles by the absence of interstitial material, the possession of well defined gap junctions between the sarcolemma of adjacent muscle fibres, abundant sarcoplasmic reticulum and numerous mitochondria. The extrinsic muscles of the clamp presumably arise from the dorso-lateral surface of the haptor and are apparently connected to the tendon of the clamp. A cluster of gland cells occurs in the haptor beneath each clamp. The haptor is richly supplied with nerve fibres which are associated with groups of neurones. Each axon is non-myelinated and contains presumed neurosecretory granules. The peripheries of some of the large axons are subdivided by invaginations of the axon wall.     

Structure of a rhamnan from the surface-layer glyco-protein of Bacillus stearothermophilus strain NRS 2004/3a

The structure of a glycan from the surface-layer glycoprotein of Bacillus stearothermophilus strain NRS 2004/3a has been studied by ¹H- and ¹³C-n.m.r. spectroscopy. The results indicate the glycan to be a polymer of the trisaccharide repeating-unit

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A metal ion-based method for the screening of nitrilases

In this paper we describe a colorimetric method for the screening of nitrilases. When a buffered solution of CoCl₂ is added to a nitrilase-catalyzed hydrolysis reaction, the ammonia product forms a complex with the cobalt ion resulting in a color change from light pink to yellow, which can readily be quantified using a spectrophotometer at 375 nm. This method has been demonstrated for both wild-type and evolved nitrilases.

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The structure of the O-antigenic chain of the lipopolysaccharide of Rhizobium trifolii 4s

The structure of the O-antigen chain of the lipopolysaccharide (LPS) of Rhizobium trifolii 4s has been determined by a combination of chemical and spectroscopic methods. The glycosyl components were found to be -rhamnose, N-acetyl- -glucosamine, and N-acetyl- -mannosamine in 3:1:1 molar proportion, as determined by gas chromatography and gas chromatography-mass spectrometry of alditol acetate and persilylated (R)-2-hydroxybutyl glycoside derivatives. The linkage positions and configurations of the glycosyl residues were obtained by 1D and 2D NMR spectroscopy. The polymer has a pentasaccharide repeating-unit containing rhammose and N-acetylglucosamine in the main chain and N-acetylmannosamine as the sole-side chain component. This latter residue is linked to a main-chain rhamnose residue. This result was suggested by NMR spectroscopy and confirmed by periodate oxidation. The sequence was deduced by 1D and 2D NMR NOE experiments and by partial hydrolysis studies. The repeating unit of the polysaccharide is shown. This constitutes the first complete structure of an O-antigenic chain of the lipopolysaccharide of any strain of Rhizobium trifolii.

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Structural studies of the O-antigen from Vibrio cholerae O:21

The O-antigen from Vibrio cholerae O:21 has been investigated, using n.m.r. spectroscopy, methylation analysis, and Smith degradation as the main methods. It is concluded that the O-antigen is composed of tetrasaccharide repeating-units having the following structure (in which Hep = -glycero- -manno-heptose).

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Synthesis of precursors for the dimeric 3-O-SO3Na Lewis X and Lewis A structures

Stereoselective syntheses of 3-O-SO₃Na-β-Gal-(1 → 4)-β-GlcNAc-(1 → 3)-β-Gal-(1 → 4)-GlcNAc-β-OBn (15) and 3-O-SO₃Na-β-Gal-(1 → 3)-β-GlcNAc-(1 → 3)-β-Gal-(1 → 3)-β-GlcNAc-(1 → 3)-β-Gal-(1 → 4)-Glc-β-OBn (25) were accomplished through the use of two novel glycosyl donors, namely, ethyl

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(8) and ethyl

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(18).     

Extracellular polysaccharide of Erwinia chrysanthemi Ech6

Many strains of Erwinia chrysanthemi, which are Gram-negative bacterial phytopathogens, produce copious amounts of extracellular polysaccharides. The extracellular polysaccharide from E. chrysanthemi pv. zeae strain SR 260, a phytopathogen of corn, is a branched-chain glucomannorhamnan of proven structure (Gray et al., Carbohydr. Res. 1993, 245, 271–287). The extracellular polysaccharide from E. chrysanthemi Ech6 is different, containing no rhamnose or mannose. It is composed of -fucose, -galactose, -glucose and -glucuronic acid in the ratio 2:2:1:1. The structure of the polysaccharide is as follows:

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2,3-BUTANEDIONE INACTIVATES THE [H]NITRENDIPINE BINDING SITES, WHEREAS DIETHYLPYROCARBONATE DOES NOT

The modification of [³H]nitrendipine binding sites in rabbit brain membranes with 2,3-butanedione and diethylpyrocarbonate was investigated. 2,3-Butanedione, an arginine-specific reagent, causes a dose- and time-dependent decrease in the number of [³H]nitrendipine binding sites without altering its dissociation constant. Scatchard analysis of the binding data shows that 50 mM 2,3-butanedione decreases the binding capacity of [³H]nitrendipine from a control value of 71 ± 6 fmol/mg of protein to 40 ± 3 fmol/mg of protein. Complete and selective protection against inactivation is provided by nifedipine. No decrease of [³H]nitrendipine binding occurs when membranes are pretreated with selective histidine reagent diethylpyrocarbonate. The results indicate that arginine but not histidine residue in

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-type calcium channel domain is critical for [³H]nitrendipine binding. Copyright © 1996 Elsevier Science Ltd     

Glycosylation with N-Troc-protected glycosyl donors

N-Troc-protected (Troc = 2,2,2-trichloroethoxycarbonyl) glucosamine and galactosamine glycosyl donors (1-O-acetyl sugar, bromo sugar, and thioglycoside) were compared with the corresponding N-Phth-protected derivatives in glycosylations of 2-(trimethylsilyl)ethanol, 2-bromoethanol, methyl 3-mercaptopropionate, N-Fmoc-protected serine, and 2-(trimethylsilyl)ethyl

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. The N-Troc-protected donors gave pure β-glycosides in somewhat higher yields than the N-Phth-protected counterparts. The N-Troc protecting group can be removed by reduction with zinc, which allows selective N-deprotection in oligosaccharides containing both N-Troc and N-Phth groups.     

Ultrastructure and histochemistry of the protonephridial system of juvenile Paramphistomum epiclitum and Fischoederius elongatus (Paramphistomidae: Digenea) during migration in Indian ruminants.

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and 1992. Ultrastructure and histochemistry of the protonephridial system of juvenile Paramphistomum epiclitum and Fischoederius elongatus (Paramphistomidae: Digenea) during migration in Indian ruminants. International Journal for Parasitology 22: 1103–1115. The protonephridial system of juvenile Paramphistomum epiclitum and Fischoederius elongatus consists of a bilaterally symmetrical arrangement of primary, secondary and tertiary ducts which connect individual flame cells with a simple common bladder. Primary and secondary ducts are formed from columns of adjoining cells which provide an epithelial lining, whose luminal surface is elaborated with either short tubercles or lamellae. Groups of cilia project from the luminal surface at frequent intervals along secondary ducts. By contrast, the tertiary ducts and bladder are lined with a nucleated syncytium which ends at a junctional complex formed with the terminal canal. The latter is continuous with the tegumental syncytium and opens at a nephridiopore on the postero-dorsal surface. Tertiary ducts of mature cercariae contain concretions which are voided by migrating juveniles in whose tertiary ducts lipids are progressively accumulated. Evidence for the role of protonephridia in excretion and possibly in osmoregulation and ionic balance is currently examined.     

Ultrastructure and histochemistry of the digestive tract of juvenile Paramphistomum epiclitum (Paramphistomidae: Digenea) during migration in Indian ruminants.

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and 1992. Ultrastructure and histochemistry of the digestive tract of juvenile Paramphistomum epiclitum (Paramphistomidae: Digenea) during migration in Indian ruminants. International Journal for Parasitology 22: 1089–1101. The digestive tract of juvenile Paramphistomum epiclitum consists of a foregut with a highly muscular terminal pharynx and an oesophagus, which leads to a pair of unbranched and blind-ending intestinal caeca. A syncytium lining the foregut is continuous with the external tegument and displays similar sensory papillae and secretory bodies (T1 and T2). A third type of secretory body (T3) is confined to the oesophageal cytons of newly excysted juveniles and is first evident in the syncytium by day 14 of migration. An epithelium lining the caeca is composed of a single layer of morphologically uniform cells whose apical surface is amplified by microvilli. Dense secretions synthesized in the caecal epithelium of mature cercariae are released during migration by a mechanism resembling modified apocrine discharge. The caecal epithelium of migrating juveniles undergoes a 10-fold increase in surface amplification (irrespective of growth) during its transition from a primarily secretory tissue to one apparently specialized for absorption.     

Synthesis of enantiomerically pure lysophosphatidylinositols and alkylphosphoinositols

A convenient synthesis for enantiomeric pure

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,

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(or and (or has been described. Starting from myo-inositol, penta-O-acetyl-myo-inositol was made in five steps. Then enantiomeric purification was done by a diastereomeric salts separation method, and the purity of each enantiomer was spectroscopically measured (¹⁹F-NMR). The phosphodiester was made via phosphoramidites. The enantiomeric products (>99% optical purity) of all compounds were easily obtained in large quantities (5–10 g). Synthetic phosphatidylinositol analogues of precisely defined structure and configuration are interesting tools for studying signal transduction mechanism and cell activity modulation.     

Cross-flow Microfiltration of Saccharomyces cerevisiae

A model which predicts the filtrate flux and the pressure drop over the length of a cross-flow hollow-fibre microfilter is presented. Data from a series of 128 experimental runs were fitted using a multi-variable, non-linear regression program. Average errors of less than 10% were found. The final equations of average flux and pressure drop were:

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Effet de la longueur d'onde de préillumination sur la désactivation des formes oxydées du donneur d'électrons du Photosystème II

Effect of preillumination wavelength on the deactivation of oxidized forms of the Photosystem II electron donor

Deactivation was studied using chlorella cells or spinach chloroplasts after an illumination of different wavelengths (light I = 710 nm, light II = 650 or 480 nm). The measurements concerned mainly the third oxidized state S₃ of the System II electron donor, according to the scheme proposed by

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, (Photochem. Photobiol., 11 (1970)457). The time course of deactivation was followed during the dark after each preillumination. Different results were obtained with algae in state 1 or state 2 as defined by

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, (Biochim. Biophys. Acta, 189 (1969) 366). In state 1 the deactivation of S₃ is faster after light 11 than after light 1; in state 2, except at the beginning of the decay, the deactivation of S₃ is almost the same after the two kinds of preillumination. With chloroplasts the deactivation is slower, but always faster after light II than after light I, no transition between state 1 and state 2 was observed. The results are discussed with reference to the possible reducing substrates of the reaction.     

Light-induced absorbance changes in Fraction I particles prepared from spinach chloroplasts by French-press treatment

Light-induced changes of absorbance were measured in Fraction 1 particles prepared from spinach chloroplasts according to a method developed by

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⁶ that employs breakage of chloroplasts in the French pressure cell and centrifugation of the resulting fragments on a sucrose density gradient. Absorbance changes were measured in the presence of ascorbate and 2,3,5,6-tetramethyl-1,4-phenylenediamine as an electron donating system. In addition to the oxidation of P₇₀₀ and cytochrome f, that was investigated in our previous study¹¹, three other light-induced absorbance changes were observed; reduction of cytochrome b with a peak at 562 nm, the so-called 515-nm change showing an absorbance increase at 515 nm and a decrease at 480 nm, and a broad band of unknown absorbance increase covering wave-lengths from 490 to 570 nm. Uncouplers such as carbonylcyanide-m-chlorophenylhydrazone and gramicidin D inhibited the 515-nm change under continuous light and accelerated the dark decay of flash-light-induced change. The other broad absorbance change was insensitive to these inhibitors.     

Insertion of isocyanides into Re---C bonds

Isocyanide-substituted Re alkyl complexes cis-p-XC₆H₄CH₂Re(CO)₄(CN-p-tolyl) (X = Cl, OMe) were prepared from the PdO-catalyzed reaction of p-XC₆H₄CH₂Re(CO)₅ (X = Cl, OMe) with p-tolyl isocyanide. On heating in toluene these complexes undergo isocyanide insertion into the Re---C bond to afford iminoacyl complexes which further react to orthometallate the p-tolyl ring. An X-ray crystal structure determination on (CO)₄

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(3a) revealed that C₁₉H₁₃ClO₄NRe crystallizes in the monoclinic space group P2₁/c with 4 formulas per unit cell. Unit cell parameters are a = 9.799 (1), B = 15.252 (2), C = 13.569 (2) Å and β = 110.788 (8)°. The structure shows Re---C bond distances indicative of substantial carbenoid character.     

Determination of the structure of a fucose-containing trisaccharide monophosphate isolated from human pregnancy urine

A new acidic oligosaccharide, isolated from the urine of a pregnant women by gel filtration and ion-exchange chromatography, was shown on the basis of sugar analysis, methylation analysis, exo-glycosidase digestion, e.i.-m.s., f.a.b.-m.s., and n.m.r. spectroscope to have the following structure:

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Inhibition of rat prostate tumor growth by an octapeptide analog of somatostatin

Analogs of a potent octapeptide analog of somatostatin (SRIF)

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were synthesized. Aromatic substitutions for Tyr resulted in little change in inhibitory potency on growth hormone (GH) secretion in the rat. Substitutions for Val or (D)Trp resulted in analogs with diminished activity. Substitution of (D)Nal for (d)Phe increased duration of GH inhibition. Final weights of subcutaneously implanted prostate tumors (R3327) were 41% lower in rats treated with an N-terminal 4-chloro-(D)phenylalanyl analog as compared to vehicle treated controls. The analog had no effect on testicular weight or final plasma testosterone levels. SRIF analogs may represent an alternative treatment for prostate cancer that would be free of the untoward reproductive effects of other treatments (e.g. LH-RH or castration).     

The structure of the exopolysaccharide of Pseudomonas fluorescens strain H13

An acidic exopolysaccharide was isolated from P. fluorescens strain H13. The structure of the polysaccharide repeating unit was determined using chemical methods and 1D and 2D NMR techniques. The repeating unit was characterized as a trisaccharide composed of -glucose, 2-acetamido-2-deoxy- -glucose and

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acid.