Probiotic supplementation influences the diversity of the intestinal microbiota during early stages of farmed Senegalese sole (Solea senegalensis, Kaup, 1858)

Ingestion of bacteria at early stages results in establishment of a primary intestinal microbiota which likely undergoes several stages along fish life. The role of this intestinal microbiota regulating body functions is crucial for larval development. Probiotics have been proved to modulate this microbiota and exert antagonistic effects against fish pathogens. In the present study, we aimed to determine bacterial diversity along different developmental stages of farmed Senegalese sole (Solea senegalensis) after feeding probiotic (Shewanella putrefaciens Pdp11) supplemented diet for a short period (10–30 days after hatching, DAH). Intestinal lumen contents of sole larvae fed control and probiotic diets were collected at 23, 56, 87, and 119 DAH and DNA was amplified using 16S rDNA bacterial domain-specific primers. Amplicons obtained were separated by denaturing gradient gel electrophoresis (DGGE), cloned, and resulting sequences compared to sequences in GenBank. Results suggest that Shewanella putrefaciens Pdp11 induces a modulation of the dominant bacterial taxa of the intestinal microbiota from 23 DAH. DGGE patterns of larvae fed the probiotic diet showed a core of bands related to Lactobacillus helveticus, Pseudomonas acephalitica, Vibrio parahaemolyticus,and Shewanella genus, together with increased Vibri o genus presence. In addition, decreased number of clones related to Photobacterium damselae subsp piscicida at 23 and 56 DAH was observed in probiotic-fed larvae. A band corresponding to Shewanella putrefaciens Pdp11 was sequenced as predominant from 23 to 119 DAH samples, confirming the colonization by the probiotics. Microbiota modulation obtained via probiotics addition emerges as an effective tool to improve Solea senegalensis larviculture.En prens

Comparison between J-aggregates in a self-assembled multilayer and polymer-bound J-aggregates in solution: a steady-state and time-resolved spectroscopic study

The self-assembly of a thiacarbocyanine dye on a charged substrate via the layer-by-layer alternate adsorption technique was studied in detail. The influence of the chemical structure of the oppositely charged polyelectrolyte (PEL) in the multilayer on J-aggregate formation was investigated by means of absorption spectroscopy and steady-state and time-resolved fluorescence spectroscopy. J-Aggregates were formed yielding a bathochromic narrow absorption band. Fine tuning of the position of the absorption band is possible by incorporating other polyelectrolytes in the multilayer. The results obtained for the dye-polyelectrolyte multilayers were compared with measurements made on the aqueous dye-polyelectrolyte mixtures. The parameters obtained by fitting the fluorescence decays to several different models allowed us to suggest a mechanism for the non-radiative decay channel. The low fluorescence quantum yields and fast non-exponential fluorescence decays obtained for both the dye-polyelectrolyte multilayers and the aqueous dye-polyelectrolyte mixtures were attributed to the trapping of a fast migrating exciton by a non-luminescent trap. The results related to J-aggregate formation, decay time and dimensionality of the aggregates were compared in solution and in a self-assembled multilayer

Y-type Langmuir-Blodgett films of 2,3-bis((2-hydroxyethyl)oxy)-6,7,10,11-tetrakis(pentyloxy)triphenylene: An X-ray reflection study

Using X-ray reflectivity, we have investigated the vertical ordering of multilayers of an asymmetrically substituted triphenylene derivative. A value of 1.37 nm is found for the thickness of an individual monolayer. Detailed fits for the reflectivity data have been performed. The corresponding electron density profiles suggest that very smooth, regular Y-type films are formed. The absence of clear Bragg peaks in the X-ray reflection curve and the small electron density fluctuations in the multilayer can be explained by an interdigitating packing of edge-on oriented disks in adjacent layers

2D-Structures of Quadruple Hydrogen Bonded Oligo(p-phenylenevinylene)s on Graphite: Self-Assembly Behavior and Expression of Chirality

The two-dimensional pattern formation of chiral oligo(p-phenylenevinylene) derivatives of different lengths containing a self-complementary hydrogen bonding motif at the liquid/solid interface has been investigated and compared using scanning tunneling microscopy. Hydrogen bonding leads to dimer formation and the chirality of the molecules is expressed at the level of packing and orientation of the dimers with respect to the substrate symmetry. Differences in expression of molecular chirality are observed as a function of molecular length and the number of stereocenters they carry. Mixing of oligomers of different length does not lead to phase separation, but to the formation of heterodimers, stressing the important role of hydrogen bonding in the self-assembly process in both solution and at the liquid/solid interface

Formation and manipulation of supramolecular structures of oligo(p-phenylenevinylene) terminated poly(propylene imine) dendrimers

A third generation poly( propylene imine) dendrimer modified with pi-conjugated oligo(p-phenylenevinylene)s forms spherical and rod-like aggregates that can be manipulated by optical tweezer

Synthesis and in vitro evaluation of dioxopyrrolopyrroles as potential low-affinity fluorescent Ca2+ indicators

2nd Mediterranean Meeting on Photochemistry -- 2003 -- Giardini Naxos, ITALYWOS: 000222779200003Three new low-affinity fluorescent Ca2+ indicators excitable with visible light, namely 3-phenyl-6-(4-(3-carboxymethoxy-4-(N,N-dicarboxymethylamino) phenyl) phenyl)-2,5-dicarboxymethyl-1,4-dihydropyrrolo[ 3,4- c] pyrrole-1,4-dione (DPP1), 3-phenyl-6-( 5-(3-carboxymethoxy-4-( N, N-dicarboxymethylamino) phenyl) thien-2-yl)-2,5-dicarboxymethyl-1,4- dihydropyrrolo[ 3,4- c] pyrrole-1,4- dione (DPP2) and 3( thien-2-yl)-6-( 5-(3-carboxymethoxy-4-( N, N-dicarboxymethylamino) phenyl) thien-2-yl)-2,5- dicarboxymethyl-1,4- dihydropyrrolo[ 3,4- c] pyrrole-1,4- dione (DPP3) have been synthesized and evaluated for their Ca2+ binding properties via fluorimetric titrations. The in vitro dissociation constant K-d measured at 21degreesC in 100 mM KCl buffered solution, pH 7.05, for the Ca2+ -DPP1 complex is 10 muM; for Ca2+ -DPP2 and Ca2+ - DPP3 a K-d value of 20 muM is found. All three indicators form 1 : 1 complexes with Ca2+. The fluorescence quantum yields of the uncomplexed forms of DPP1, DPP2 and DPP3 are 1.2 x 10(-2), 3.4 x 10(-2) and 3.6 x 10(-2), respectively. After binding to Ca2+ these values increase to 4.8 x 10(-2), 5.0 x 10(-2) and 5.1 x 10(-2), respectively.Italian Grp Photoche

Scanning tunneling microscopy and spectroscopy of donor-acceptor-donor triads at the liquid/solid interface

By means of scanning tunneling microscopy (STM), the self-assembly of two organic donor-acceptor-donor triads (donor=oligo(p-phenylene vinylene) (OPV); acceptor=perylene diimide (PDI)) and their mixtures has been investigated at the liquid/solid interface. Both triads differ in the nature of the substituents and, therefore, in the redox properties of the central perylene diimide unit (H or Cl). Thanks to the submolecular resolution, the distinct electronic properties of the units, within a triad and between the two triads, are reflected by the relative STM contrast in the bias-dependent imaging experiments. Moreover, scanning tunneling spectroscopy reveals an inverse rectifying behavior of the OPV and H-substituted PDI units, which is discussed in the framework of quasi-resonant tunneling. A striking difference is observed for the Cl-substituted triad