O. V. Petrova

Identification and first insights into the structure and biosynthesis of chitin from the freshwater sponge Spongilla lacustris

This work demonstrates that chitin is an important structural component within the skeletal fibers of the freshwater sponge Spongilla lacustris. Using a variety of analytical techniques ((13)C solid state NMR, FT-IR, Raman, NEXAFS, ESI-MS, Morgan-Elson assay and Calcofluor White Staining); we show that this sponge chitin is much closer to α-chitin, known to be present in other animals, than to β-chitin. Genetic analysis confirmed the presence of chitin synthases, which are described for the first time in a sponge. The presence of chitin in both marine (demosponges and hexactinellids) and freshwater sponges indicates that this important structural biopolymer was already present in their common ancestor.

General Route to Symmetric and Asymmetric meso-CF3-3(5)-Aryl(hetaryl)- and 3,5-Diaryl(dihetaryl)-BODIPY Dyes

A general efficient route to hitherto inaccessible symmetric and asymmetric meso-CF(3)-BODIPY dyes has been developed. The key stages include the reduction of available 2-trifluoroacetylpyrroles to the corresponding alcohols which are further condensed with pyrroles. The method allows the BODIPY with 3(5)aryl(hetaryl) and 3,5-diaryl(hetaryl) substituents to be readily assembled. The BODIPY dyes synthesized fluoresce (Φ(f) = 0.56-1.00) in the 560-680 nm region.

Isolation and identification of chitin in the black coral Parantipathes larix (Anthozoa: Cnidaria)

Until now, there is a lack of knowledge about the presence of chitin in numerous representatives of corals (Cnidaria). However, investigations concerning the chitin-based skeletal organization in different coral taxa are significant from biochemical, structural, developmental, ecological and evolutionary points of view. In this paper, we present a thorough screening for the presence of chitin within the skeletal formations of a poorly investigated Mediterranean black coral, Parantipathes larix (Esper, 1792), as a typical representative of the Schizopathidae family. Using a wide array variety of techniques ((13)C solid state NMR, Fourier transform infrared (FTIR), Raman, NEXAFS, Morgan-Elson assay and Calcofluor White Staining), we unambiguously show for the first time that chitin is an important component within the skeletal stalks as well as pinnules of this coral.

First report on chitinous holdfast in sponges (Porifera).

A holdfast is a root- or basal plate-like structure of principal importance that anchors aquatic sessile organisms, including sponges, to hard substrates. There is to date little information about the nature and origin of sponges’ holdfasts in both marine and freshwater environments. This work, to our knowledge, demonstrates for the first time that chitin is an important structural component within holdfasts of the endemic freshwater demosponge Lubomirskia baicalensis. Using a variety of techniques (near-edge X-ray absorption fine structure, Raman, electrospray ionization mas spectrometry, Morgan–Elson assay and Calcofluor White staining), we show that chitin from the sponge holdfast is much closer to α-chitin than to β-chitin. Most of the three-dimensional fibrous skeleton of this sponge consists of spicule-containing proteinaceous spongin. Intriguingly, the chitinous holdfast is not spongin-based, and is ontogenetically the oldest part of the sponge body. Sequencing revealed the presence of four previously undescribed genes encoding chitin synthases in the L. baicalensis sponge. This discovery of chitin within freshwater sponge holdfasts highlights the novel and specific functions of this biopolymer within these ancient sessile invertebrates.

Pyrrole-2-dithiocarboxylates: Synthesis of 2-(1-Alkylthio-2-cyanoethenyl)pyrroles

Abstract 2-(1-Alkylthio-2-cyanoethenyl)pyrroles were synthesized in good to high yields by reaction of pyrrole-2-dithiocarboxylates with active methylene nitriles in a KOH-DMSO medium. The condensation of 4,5,6,7-tetrahydroindole with cyanoacetate also leads to 1-ethylthio-2-cyano-4,5,6,7-tetrahydrocyclohexa-[c]-3H-pyrrolizin-3-one in 61% yield. The effect of substituent on the reaction course has been studied. The dipole moments and spectral characteristics of products are presented.

Cell-to-cell communication in the populations of enterobacterium Erwinia carotovora ssp. atroseptica SCRI1043 during adaptation to stress conditions

Erwinia carotovora ssp. atroseptica SCRI1043 is a plant pathogenic bacterium. Many species of enterobacteria including Erwinia sp. can induce the onset or the progression of opportunistic or persistent infections in humans. The existence of these bacteria within different ecological niches is related to their significant adaptive potential. The triggering of adaptive reactions, which are needed for bacterial persistence, is controlled in many cases by intercellular communication; hence, the ability to survive under unfavourable conditions is regulated in a cell-density-dependent manner. In this study, we showed that, during starvation of E. carotovora ssp. atroseptica SCRI1043, the initial stage of the response to stress was stabilization of the density of culturable cells in the range 10(6)-10(7) CFU mL(-1). The number of culturable cells increased (up to approximately 10(6) CFU mL(-1)) when cultures were inoculated at a low cell density (10(3)-10(5) CFU mL(-1)), and at the same time, acylhomoserine lactone (AHL)-dependent quorum sensing was activated. Our results showed that the regulation of cell density in starving populations of E. carotovora ssp. atroseptica SCRI1043 occurred and this regulation was carried out with the involvement of the cell-to-cell communication.

Synthesis of 2-benzoylethynylpyrroles by cross coupling of 2-arylpyrroles with 1-benzoyl-2-bromoacetylene over aluminum oxide

Cross coupling of 2-arylpyrrole with benzoylbromoacetylene over aluminum oxide at room temperature gave 45–94% of 2-(benzoylethynyl)-5-arylpyrroles. Intermediate 2-(2-benzoyl-1-bromoethenyl)-5-arylpyrroles were isolated in up to 19% yield. The reaction was accompanied by formation of less than 5% of adducts of the initial pyrroles with the cross-coupling products, 2-benzoyl-1,1-bis(5-arylpyrrol-2-yl)ethenes.

1,2-Dioximes in the trofimov reaction

Abstract3,3′-Dimethyl-1,1′-divinyl-2,2′-dipyrrole was obtained during the reaction of 3,4-hexanedione dioximes with acetylene under pressure in the potassium hydroxide-DMSO system. In the case of 1,2-cyclohexanedione dioxime 2,2′-dipyrrole and 2-pyridyl-and 2-acylpyrroles were isolated. α-Benzil and α-furil dioximes give 3,4-diphenyl-and 3,4-di(2-furyl)-1,2,5-oxadiazoles respectively in addition to their mono-and divinyl derivatives.

Synthesis of secondary propargyl alcohols from aromatic and heteroaromatic aldehydes and acetylene in the system KOH-H2O-DMSO

Ethynylation of aromatic and heteroaromatic aldehydes with acetylene under atmospheric pressure in the catalytic system KOH-H2O-DMSO (aldehyde-KOH molar ratio 1 : 2, −5 to −7°C, 3 h) gave secondary propargyl alcohols in 46–67% yield.

Functionally substituted 1,3-diethenyl [1,2- c ][1,3]pyrrolothiazoles from pyrrole-2-carbodithioates

The reaction of pyrrole-2-carbodithioates with methylenoactive nitriles and 2-benzoyl-1-bromoacetylene in the KOH-DMSO system leads to functionally substituted pyrrolothiazoles in 59-85% yield.