Reactivity of platina-β-diketones towards chelating nitrogen and sulfur donors: formation of acyl(hydrido)platinum(IV) and acyl(chloro)platinum(II) complexes

The platina-β-diketone [Pt₂{(COMe)₂H}₂(μ-Cl)₂] (1) was found to react with chelating N,N-ligands 2(R^′NCR)C₅H₄N (R/R^′=Ph/OH, H/Ph, Me/Ph) to form acyl(hydrido)platinum(IV) complexes [Pt(COMe)₂Cl(H){2-(R^′NCR)C₅H₄N}] (R/R^′=Ph/OH 2a; H/Ph 2b; Me/Ph (2c)). Reactions of complex 1 with chelating S,S- and N,S-donors (RS-CH₂-CH₂-SR, 2-(RSCH₂)C₅H₄N, R=Et, Ph, t-Bu) afforded acyl(chloro)platinum(II) complexes [Pt(COMe)Cl(RSCH₂CH₂SR)] (R=Et, 3a; Ph, 3b; t-Bu, 3c) and [Pt(COMe)Cl{2-(RSCH₂)C₅H₄N}] (R=Et, 4a; Ph, 4b; t-Bu, 4c), respectively. All complexes were fully characterized by microanalysis, IR and NMR (¹H, ¹³C) spectroscopy. Furthermore, molecular structures of complexes 3b and 4b were determined by single-crystal X-ray diffraction analyses revealing close to square-planar configuration. In complex 4b the acetyl ligand is trans to pyridine N atom (configuration index SP-4-2). The reactions are discussed in terms of consecutive oxidative addition and reductive elimination reactions.     

Effects of phospholipid acyl chain structure on thermotropic phase properties. 3. Phosphatidylcholines with (−), and (±)-anteiso acyl chains

We have synthesized a number of anteiso-branched fatty acids, both as racemates and as pure (?)-stereoisomers, as well as the corresponding di-anteiso-acyl phosphatidylcholines (PCs). The phase transition temperatures (_c of the hydrated PCs have been determined by differential thermal analysis (DTA). Consideration of the observed effects of acyl chain length and terminal see-butyl group configuration on anteiso acid melting points and di-anteiso-acyl PC transition temperatures leads us to the conclusion that the terminal branched portions of anteiso acyl chains interact only weakly with adjacent acyl chains in the hydrated phosphatidylcholine bilayer and probably in the anhydrous fatty acid crystal as well. In agreement with this conclusion, we observe that the DTA heating transition endotherms for hydrated di-anteiso-acyl PCs appear to be considerably less strongly endothermic, and occur at much lower temperatures, than do the major transition endotherms for the di-n-acyl PCs of like carbon number. Our findings generally support the proposal that anteiso acyl lipids tend to fluidize membranes, although they do so less effectively than do cis-unsaturated acyl lipids.     

Inverse acyl phosph(on)ates: substrates or inhibitors of beta-lactam-recognizing enzymes?

Acyl phosph(on)ates represent a new class of inhibitors of beta-lactam-recognizing enzymes. Previously described members of this class were aroyl phosph(on)ates. These compounds have been shown to acylate and/or phosphylate the active site serine residue, leading to either transient or essentially irreversible inhibition [Li, N., and Pratt, R. F. (1998) J. Am. Chem. Soc.120, 4264-4268]. The present paper describes the synthesis and evaluation as inhibitors of an inverse pair of acyl phosph(on)ates that incorporate the amido side chain that represents a major substrate specificity determinant of these enzymes. Thus, N-(phenylacetyl)glycyl phenyl phosphate and benzoyl N-(benzyloxycarbonyl)aminomethyl phosphonate were prepared. The former of these compounds was found to be a substrate of typical class A and C beta-lactamases and of the DD-peptidase of Streptomyces R61; it thus acylates the active site serine. In contrast, the latter compound was an irreversible inhibitor of the above enzymes, probably by phosphonylation of the active site serine. With each of these enzymes therefore, the amido side chain rather than the acyl group dictates the orientation of the bound phosph(on)ate and thus the mode of reaction.     

Chirality of the acyl group of β-hydroxy-β-methylglutarylhydroxyabscisic acid

The β-carbon of the acyl group of β-hydroxy-β-methylglutarylhydroxyabscisic acid was shown to possess R-configuration by HPLC analysis of the reduced product.     

Total synthesis of (±)-elegansidiol, (±)-farnesiferol B,and (±)-farnesiferol D

The racemic total synthesis of elegansidiol, farnesiferol B, and farnesiferol D has been obtained following a Diels–Alder approach. Gillman addition, cross metathesis reaction are the other key steps involved in the target synthesis.     

Immunohistochemical analysis of adhesive papillae of Clavelina lepadiformis (Müller, 1776) and Clavelina phlegraea (Salfi, 1929) (Tunicata,Ascidiacea)

Almost all ascidian larvae bear three mucus secreting and sensory organs, the adhesive papillae, at the anterior end of the trunk, which play an important role during the settlement phase. The morphology and the cellular composition of these organs varies greatly in the different species. The larvae of the Clavelina genus bear simple bulbous papillae, which are considered to have only a secretory function. We analysed the adhesive papillae of two species belonging to this genus, C. lepadiformis and C. phlegraea, by histological sections and by immunolocalisation of β-tubulin and serotonin, in order to better clarify the cellular composition of these organs. We demonstrated that they contain at least two types of neurons: central neurons, bearing microvilli, and peripheral ciliated neurons. Peripheral neurons of C. lepadiformis contain serotonin. We suggest that these two neurons play different roles during settlement: the central ones may be chemo- or mechanoreceptors that sense the substratum, and the peripheral ones may be involved in the mechanism that triggers metamorphosis.Key words: Settlement, neurotransmitter, serotonin, β-tubulin, papillary nerves, metamorphosis.Ascidians (phylum Chordata; subphylum Tunicata) are sessile filter-feeding organisms that can be found in all benthic marine environments and develop through a swimming tadpole larva. Larvae of colonial ascidians have a short planktonic life that can vary from minutes to hours (Burighel and Cloney, 1997). Prior to metamorphosis, the larva attaches to the substratum by means of peculiar organs of ectodermic origin, located in the anterior region of the trunk. These organs, known as adhesive papillae, secrete sticky substances and effect primary adhesion of the larva to the substrate (Cloney, 1977). They have an important role in the initiation of settlement and metamorphosis and there is evidence that, at least in some species, they participate in substrate selection (Torrence and Cloney, 1983; Svane and Young, 1989; Groppelli et al., 2003). In many species, they are organised in a triangular field, whereas in others they are aligned along the mid-sagittal plane of the trunk. Adhesive papillae have been classified into two types: eversible papillae, typical of some colonial species, composed by several cell types and rapidly changing shape as they touch the substrate, and non-eversible papillae, typical of solitary species, which do not change shape after settlement (Burighel and Cloney, 1997).With few exceptions, all adhesive papillae are formed by elongated secretory and sensory cells, which are recognised as primary neurons (Cloney, 1977, 1979). It has been proposed that sensory cells may detect the chemical and physical characteristics of the substratum at potential sites for settlement and metamorphosis (Young and Braithwaite, 1980; Groppelli et al., 2003).The presence of primary neurons in the papillae has been reported in the larvae of several species such as Distaplia occidentalis, Diplosoma macdonaldi, Phallusia mammillata, Ciona intestinalis and Ascidia malaca (Cloney, 1977;Torrence and Cloney, 1983; Sotgia et al., 1998; Takamura, 1998; Gianguzza et al., 1999).These neurons have axons that join together to form the papillary nerves that enter the central nervous system at the level of the sensory vesicle (Imai and Meinertzhagen, 2007).Recently, different neurotransmitters have been localised in the sensory neurons of the papillae of different species. The presence of GABAergic neurons has been reported in the papillae of Ciona savygni (Brown et al., 2005) and of Ciona intestinalis (Zega et al., 2008), while serotonergic neurons have been localised in the papillae of Phallusia mammillata (Pennati et al., 2001) and Botrylloides leachi (Pennati et al., 2007). Moreover, it has been demonstrated that serotonin plays a role in the mechanism triggering metamorphosis in ascidians (Zega et al., 2005).After attachment, all papillae retract to draw the larva closer to the substratum. In the colonial ascidian Distaplia occidentalis, the process of retraction is reversibly inhibited by cytochalasin B, suggesting that microfilaments are involved in this process (Cloney, 1979).Clavelina lepadiformis is a colonial species, whose larvae bear non-eversible simple bulbous papillae.They have been described as being formed only by columnar glandular cells, whose secreted material is responsible for the sticky properties of the organ. These papillae do not contain sensory cells and were considered the simplest among those studied (Turon, 1991).In this work, the morphology of the adhesive papillae of C. lepadiformis and C. phlegraea was further investigated by histological analysis and immunolabelling techniques in order to clarify the actual cellular composition and function of these organs.     

The roles of the Chantransia phase of Lemanea (Lemaneaceae,Batrachospermales, Rhodophyta) and of the ‘Mushroom’ phase of Himanthalia (Himanthaliaceae,Fucales, Phaeophyta)

Summary

The life cycle of the Batrachospermales (freshwater florideophyte red such as Batrachospermum, Lemanea) is a shortened variant of the ‘normal’ marine florideophyte life cycle. The perennial Chantransia diploid phase is microscopic and encrusting. Each winter it produces one or more semi-erect haploid gametophytes by vegetative meiosis. Gamete production and fertilization is followed by production of diploid carposporophytes; these produce diploid carpospores which disperse, and regenerate the Chantransia phase. The question of the extent to which the Chantransia phase contributes resources to the gametophyte was approached by physiological-hydrodynamic modelling. These computations suggest that the photosynthetic rates in situ on an area basis are 20 times greater for the gametophyte than the Chantransia phase; this agrees with the observed ratios of peak biomass. The conclusion is that the Chantransia phase has a negligible role in provisioning the growing gametophyte, and that the role of the Chantransia phase is to occupy space with living biomass throughout the year, including exposure at summer drawdown, and (perhaps) by dispersal via production of monospores. A similar conclusion is arrived at on the basis of biomass data for the role of the perennial ‘mushroom’ phase of the semelparous marine Fucalean brown alga Himanthalia elongata in relation to the short-lived but much larger reproductive receptacles.     

Mössbauer and NMR studies of protonated acyl diphosphaferrocenes

The acyl derivatives of 3,3′,4,4′-tetramethyldi- phosphaferrocene (TMDPF) have been examined in strong acids by ⁵⁷Fe Mössbauer, ¹H and ³¹P NMR spectroscopy. As with ferrocenyl ketones, protonation was found to occur at the keto function, the diphosphaferrocenyl ketones having comparable or, in some cases, reduced basicities compared to ferrocenyl ketones. [p ]Trends in the ⁵⁷Fe Mössbauer parameters are not as additive as in ferrocene systems due to steric crowding. The keto derivatives show some unusual deuteriation patterns and these have been compared with those of ferrocenyl ketones. The ¹³C spectra of several derivatives have been reported to illustrate the rather complex stereochemistry found in these derivatives.     

Life history of Lineus viridis (Müller, 1774) (Heteronemertea, Nemertea)

Lineus viridis is a common nemertean species of North-Atlantic intertidal sand flats. Its mating behaviour is peculiar insofar as this species is reported to be polyandric. However, detailed information on this topic is lacking. In order to get more data on the reproduction, oogenesis and life history of this species, a population in the Wadden Sea on the Isle of Sylt (North Sea) was studied between 2005 and 2011. We conducted regular surveys, during which we sampled, measured and recorded the sex status of 25–100 individuals at each sampling event; at least three individuals were fixed for histological studies at each sampling date. In addition, animals were kept in the laboratory for 3?years to complement field data on sexual identity. Lineus viridis was found to reproduce annually in several successive year; the females are significantly larger than the males. Oogenesis starts in spring, shortly after the preceding reproductive period, and continues until the end of December. Spermiogenesis starts in late autumn and also ends late in December. During mating, several males are generally found crawling on a single female, which forms a cocoon that encloses both the female and the associated males. Fertilization is internal. While females discharge all of their eggs during a single mating event and lose more than 40% of their wet weight, males only empty a few of their gonads, and are thus able to fertilize more than one female. Our study clearly shows that Lineus viridis is a perennial, iteroparous species with a pronounced sexual size dimorphism. During this long-term study, no evidence for sequential hermaphroditism has been found. The observed polyandric mating system in this species raises further questions regarding mate and sperm competition that deserve additional research.     

Redescription of Skrjabinodon medinae (García-Calvente, 1948) (Nematoda: Pharyngodonidae) from the cloaca of Podarcis pityusensis (Bosca, 1883) (Sauria: Lacertidae) of the Balearic Islands (Spain)

Pharyngodon medinae García-Calvente, 1948 (Nematoda: Pharyngodonidae) is redescribed from Podarcis pityusensis (Bosca, 1883) (Sauria: Lacertidae) of the Balearic Islands (Spain) and confirmed as a member of the genus Skrjabinodon Inglis, 1968. A systematic review of S. medinae and closely related species is also given. Parathelandros canariensis is referred to Skrjabinodon as a new combination and Parathelandros Magzoub et al., 1980 is dismissed as a junior homonym of Parathelandros Baylis, 1930.     

The effects of (22S,23S)- and (22R,23R)-3β-hydroxy-22,23-oxido-5α-ergost-8(14)-en-15-ones on biosynthesis of cholesteryl esters and activity of acyl-CoA:Cholesterol acyl transferase in Hep G2 cells

Novel synthetic oxysterols (22S,23S)-3β-hydroxy-22,23-oxido-5α-ergost-8(14)-en-15-one (I) and (22R,23R)-3β-hydroxy-22,23-oxido-5α-ergost-8(14)-en-15-one (II) influenced biosynthesis of cholesteryl esters from [¹⁴C]acetate (85% and 180% of control at 5 μM concentration) in the human hepatoma Hep G2 cell line. Ketosterol (I) increased the level of cholesteryl ester biosynthesis from [¹⁴C]oleate in Hep G2 cells in a dose dependent manner, whereas the level of cholesteryl esters biosynthesis in the presence of ketosterol (II) reached the maximal value (269±20% of control) at 1 μM concentration of this compound. In a cell free system ketosterol (I) increased the rate of ACAT-dependent cholesterol acylation similar to 25-hydroxycholesterol, however, ketosterol (II)), efficiently stimulated an initial rate of ACAT-catalyzed cholesterol esterification, followed by rapid inactivation of this enzyme.     

Phylogenetic utility of protein (RPB2, β-tubulin) and ribosomal (LSU,SSU) gene sequences in the systematics of Sordariomycetes (Ascomycota,Fungi)

The Sordariomycetes is an important group of fungi whose taxonomic relationships and classification is obscure. There is presently no multi-gene molecular phylogeny that addresses evolutionary relationships among different classes and orders. In this study, phylogenetic analyses with a broad taxon sampling of the Sordariomycetes were conducted to evaluate the utility of four gene regions (LSU rDNA, SSU rDNA, beta-tubulin and RPB2) for inferring evolutionary relationships at different taxonomic ranks. Single and multi-gene genealogies inferred from Bayesian and Maximum Parsimony analyses were compared in individual and combined datasets. At the subclass level, SSU rDNA phylogenies demonstrate their utility as a marker to infer phylogenetic relationships at higher levels. All analyses with SSU rDNA alone, combined LSU rDNA and SSU rDNA, and the combined 28 S rDNA, SSU rDNA and RPB2 datasets resulted in three subclasses: Hypocreomycetidae, Sordariomycetidae and Xylariomycetidae, which correspond well to established morphological classification schemes. At the ordinal level, the best resolved phylogeny was obtained from the combined LSU rDNA and SSU rDNA datasets. Individually, the RPB2 gene dataset resulted in significantly higher number of parsimony informative characters. Our results supported the recent separation of Boliniaceae, Chaetosphaeriaceae and Coniochaetaceae from Sordariales and placement of Coronophorales in Hypocreomycetidae. Microascales was found to be paraphyletic and Ceratocystis is phylogenetically associated to Faurelina, while Microascus and Petriella formed another clade and basal to other members of Halosphaeriales. In addition, the order Lulworthiales does not appear to fit in any of the three subclasses. Congruence between morphological and molecular classification schemes is discussed.     

Tabanidae (Diptera) of State of Maranhão, Brazil II. Description of Esenbeckia (Esenbeckia) rafaeli, sp. nov

Esenbeckia (Esenbeckia) rafaeli, sp.nov. is described and figured from nine specimens collected in Carolina, state of Maranh?o, Brazil. The new species is compared with the species Esenbeckia (Esenbeckia) laticlava Wilkerson & Fairchild, 1983; Esenbeckia (Esenbeckia) bitriangulata Lutz & Castro, 1935 e Esenbeckia (Esenbeckia) enderleini Kr?ber, 1931.     

Palaeontology of the Purbeck-type (Tithonian,Late Jurassic) bonebeds of Chassiron (Oléron Island,western France)

The paralic flora and fauna from the Late Jurassic of Chassiron (Oléron Island, western France) are described. The Tithonian-aged bonebeds of Purbeck facies of this locality have yielded a rich and diverse vertebrate assemblage including fishes, amphibians, reptiles and mammals, alongside numerous plant and invertebrate remains. The Chassiron locality thus appears as a peculiar Konzentrat-Lagerstätte in which most of the palaeoecosystem's biological components (both aquatic and terrestrial) have been preserved. The depositional environment was probably subject to salinity fluctuations, as indicated by the co-occurrence of freshwater and euryhaline organisms. This is one of the richest localities and the first mammal-bearing site known from the Jurassic of France.     

DFT study of (17)O, (1)H and (13)C NMR chemical shifts in two forms of native cellulose, I(α) and I(β)

This computational study is intended to shed light on the crystalline and molecular structure, together with the hydrogen bonding (H-bonding) differences between two forms of native cellulose. DFT calculations were carried out to characterize the ¹⁷O, ¹H and ¹³C nuclear magnetic resonance (NMR) parameters in cellulose I_α and I_β with the B3LYP functional employing the 6–311++G7 and 6–31+G1 basis sets. Geometry optimization revealed that the average HB length is shortened by 0.01–0.08 Å when the chains are aligned, whereas the average bond angle increases by about 4–8° exhibiting the enhancement of HB strength. For the isolated cellotetramer chains, the isotropic ¹⁷O–H chemical shifts were plotted as a function of HB length. Our results indicated that as the HB length in cellotetramer I_α increases, the ¹⁷O–H chemical shift isotropy increases, but this parameter changes in the opposite direction for the other structure. Moreover, B3LYP/6–311++G7 calculations reveal that there is an acceptable correlation between the calculated ¹³C chemical shifts of the two structures and their experimental values.     

Biochemical characterisation of digestive α-amylase of Red Palm Weevil,Rhynchophorus ferrugineus (Olivier, 1790) (Coleoptera: Curculionidae)

The Red Palm Weevil, Rhynchophorus ferrugineus (Oliver) (Coleoptera: Curculionidae), is a serious pest of a wide range of plant species including coconut, sago, date and oil palms. The α-amylases are the hydrolytic enzymes that are involved in carbohydrate metabolism in insects. So far nothing is done to demonstrate α-amylase activity of R. ferrugineus. Thus, the aim of the current study was to identify and characterise the α-amylase activity to gain a better understanding of digestive physiology of the insect. Thus, the α-amylase in the gut of red palm weevil was isolated and characterised using starch as a substrate. The study showed that the α-amylase is present in the gut of the insect for carbohydrate digestion. The α-amylase has an optimum pH and temperature of 5 and 40°C. The activity of α-amylase was increased by NaCl and KCl and inhibited by other compounds such as MgCl₂, CaCl₂, urea, ethylenediaminetetraacetic acid and sodium dodecylsulfate. Native-PAGE electrophoresis of α-amylase showed two isoenzymes, one major and one minor band showing α-amylase importance in the carbohydrate metabolism of the insect. Understanding of the digestive physiology and α-amylase activity of Red Palm Weevil is important when new management strategies for this economically important pest are devised.     

Amino acid–dependent stability of the acyl linkage in aminoacyl-tRNA

Aminoacyl-tRNAs are the biologically active substrates for peptide bond formation in protein synthesis. The stability of the acyl linkage in each aminoacyl-tRNA, formed through an ester bond that connects the amino acid carboxyl group with the tRNA terminal 3′-OH group, is thus important. While the ester linkage is the same for all aminoacyl-tRNAs, the stability of each is not well characterized, thus limiting insight into the fundamental process of peptide bond formation. Here, we show, by analysis of the half-lives of 12 of the 22 natural aminoacyl-tRNAs used in peptide bond formation, that the stability of the acyl linkage is effectively determined only by the chemical nature of the amino acid side chain. Even the chirality of the side chain exhibits little influence. Proline confers the lowest stability to the linkage, while isoleucine and valine confer the highest, whereas the nucleotide sequence in the tRNA provides negligible contribution to the stability. We find that, among the variables tested, the protein translation factor EF-Tu is the only one that can protect a weak acyl linkage from hydrolysis. These results suggest that each amino acid plays an active role in determining its own stability in the acyl linkage to tRNA, but that EF-Tu overrides this individuality and protects the acyl linkage stability for protein synthesis on the ribosome.     

First report of Triatoma nigromaculata (Stål, 1859) (Hemiptera, Reduviidae, Triatominae) for Colombia

The presence of Triatoma nigromaculata was recorded for the first time in Colombia in the rural village La Playa in the province of Cauca. A single female was captured from an outdoor area near a household. The presence of Trypanosoma parasites in the specimen was not established due to the poor condition of the specimen. The epidemiological importance of this finding is discussed with respect to the potential for transmission of Chagas disease in the province of Cauca and, more broadly, in Colombia.     

The muscular system of the ovipositor of Spaziphora hydromyzina (Fallén) (Diptera, Scathophagidae)

The structure of the ovipositor sclerites and muscles was investigated in Spaziphora hydromyzina (Diptera, Scathophagidae).