International Society for Reef Studies

International Society for Reef Studies     

Asymmetric hydrolysis of dimethyl 3-phenylglutarate catalyzed by Lecitase Ultra: Effect of the immobilization protocol on its catalytic properties

The asymmetric hydrolysis of dimethyl 3-phenylglutarate (1) by different immobilized preparations of a phospholipase A₁ (Lecitase Ultra (LECI)) at pH 7 and 25 °C has been studied. Agarose beads coated with octyl, cyanogen bromide (CNBr), polyethylenimine (PEI) or glyoxyl groups were used as supports for the immobilization of LECI. The different derivatives behaved very differently in terms of activity, discrimination between 1 and methyl 3-phenylglutarate (2) resulting from the hydrolysis of 1, enantioselectivity (in the hydrolysis of 1 to produce R or S-2) and enantiospecificity in the hydrolysis of R-2 and S-2. Using 1 mM of 1, CNBr-LECI showed the highest activity (13 × 10⁻³ μmol/min mg protein) while octyl-LECI was about 20 times less active. All the enzyme preparations mainly produced (S)-2, but with different enantioselectivity. CNBr-Lecitase was the most enantioselective, producing the S-2 10 fold more rapidly than the R-2, while octyl-Lecitase gave only half of that difference.LECI adsorbed on octyl-agarose allowed to get a yield up to 99% of S-2 (ee was 66%). The reaction stopped in the monoester and no isomer of this compound was further hydrolyzed by the enzyme. However, when the reaction was catalyzed by the other immobilized LECI preparations, the enzyme was able to hydrolyze mainly the minority isomer, permitting to improve the ee of the remaining S-2. The best results were obtained using CNBr-LECI, which gave (S)-methyl-3-phenylglutarate with a yield of 80% and an ee exceeding 99%.     

Méthodologies et générations d’aérosol innovants appliqués à la vectorisation pulmonaire en pédiatrie

No aerosol system on the market is perfectly suited for aerosol therapy in infants. The RESPIRE project aims to answer this need by developing an innovative piezoelectric microperforated vibrating membrane nebulizer, the Baby Nimbus?; efficient, fast, portable and silent. Consisting of three complementary partners, the project was divided into three phases: technology development by the company Télémaq (Sophia Antipolis), in vitro and in vivo test performed on baboons by Inserm U618 (Tours), clinical trials in infants led by AP–HM (Marseille). Studies conducted by Inserm U618 and AP–HM focused on the influence of particle size on lung deposition in baboons and the clinical score in infants. Three devices of different droplet sizes were compared in the in vivo study, the Pari LC Sprint SP^® (Pari, Germany, MMAD 4.5μm – flow 0.18 mL/min), the E-Flow Rapid^® (Pari, Germany, MMAD 4.8μm – flow 0.35 mL/min) and Baby Nimbus? (Télémaq, France). Four versions of Baby Nimbus? were needed to achieve the MMAD of 2.4 μm and flowrate of 0.4 mL/min (Spraytec^®, Malvern, England). Preliminary in vivo results show that the amount of the initial charge deposited in the lungs is 0.9% for the Pari LC Sprint SP^®, 1.2% for E-Flow Rapid^® and 2.2% for the Baby Nimbus?. Additional in vivo tests and clinical trials are under way to rule definitively on the efficiency provided by the Baby Nimbus?.     

Parasitoid vibrations as potential releasing stimulus of evasive behaviour in a leafminer

Abstract. The aim of this study was to characterize the vibratory signals produced by the parasitoid Sympiesis sericeicornis Nees (Hymenoptera: Eulophidae) while foraging on apple leaves infested by one of its hosts, the spotted tentiform leafminer Phyllonorycter malella (Ger.) (Lepidoptera: Gracillariidae).This leafminer changes its behaviour as a function of the parasitoid's behaviour to escape parasitization.We propose that the leafminer uses vibrations triggered by the parasitoid to detect the presence of its enemy.We measured vibrations produced by a foraging parasitoid on a mine with a laser vibrometer.By recording concurrently the behaviour of the parasitoid on video, vibrations could be assigned to particular behaviours.Subsequently, vibrations were characterized by their dominant frequencies and intensities.The behaviours Landing and Take-off both produced strong impact-like vibrations characterized by an initial irregular phase during which frequencies up to 25 kHz occurred followed by a slow decaying regular phase.Vibrations elicited by Moving, Standing and Probing showed no clear temporal pattern.During Probing , dominant frequencies of up to 5.6 kHz were observed frequently at intensities well above the background noise (>10 dB).During Moving and Standing , vibrations were more scarce and of lower frequencies and intensities.Due to their impact-like nature, vibrations produced by Landing and Take-off are probably not specific to the parasitoid.Vibrations produced by Moving and Standing are difficult to detect and not reliable because of their non-specificity.Therefore, only Probing provides a reliable and detectable source of information for the host.The vibrations elicited during Probing could account for the evasive behaviour that is observed in this and other leafminers.     

Phylogeny of the Drosophila obscura group as inferred from one- and two-dimensional protein electrophoresis

The phylogenetic relationships of 15 species of the obscura group of Drosophila were analysed by use of one- and two-dimensional electrophoresis. Genetic distances based on two-dimensional data are five times smaller than those based on native proteins. From the data, it is proposed that the species radiation of the obscura group happened in two evolutionary bursts, the first one giving rise to at least four palearctic proto-lineages (bifasciata, obscura (including D. subsilvestris), subobscura, and microlabis) and one or two proto-nearctic lineages (affinis, pseudoobscura), and the second, more recent burst giving rise to the current speciation within lineages.     

Conducting Studies with Fathers: Challenges and Opportunities

Traditionally, researchers interested in understanding father involvement in the lives of young children have relied on mothers as proxy respondents for fathers, yet recent research has made noteworthy strides in collecting data from fathers themselves yielding an unprecedented wealth of data on fathers' involvement in their children's lives. Despite this progress, there remain many methodological challenges in conducting studies with fathers and their children. Therefore, this article highlights several methodological challenges, including the identification of fathers, recruitment of fathers as participants, and retention of participants in small-scale studies with longitudinal designs, and discusses the advantages and disadvantages of several strategies our research team and others have used to collect data from fathers. The paper concludes with a set of suggestions for improving methodological approaches in fatherhood research, as well as remaining challenges in this area of study.     

A new formulated stable papin-pectin aerosol spray for skin wound healing

A new spray-on topical wound debrider composition consisting of 0.1% w/v papain immobilized in 6% w/v pectin gel was formulated for skin wound healing. The stability of the enzyme activity of this new formulated spray was compared with the 0.1% w/v papain in water solution at the refrigerated temperature of 4 and 75°C. Two aerosol propellants, air and nitrogen, were evaluated for their efficacy. The new formulated spray was then evaluated for its thermal stability under air and N₂ at 75°C. All enzyme activity of papain was measured with a spectrophotometer using casein as a substrate at 37°C and in 0.1 M phosphate buffer at pH 6, as well as trichloral acetic acid to separate the product of casein hydrolysis. All the evaluations showed the new aerosol spray formulation to be far better than the liquid formulation in storage stability and thermal stability at 75°C under atmospheric or higher pressures. The new formulation was tested in a rabbit experiment to evaluate the effectiveness of wound healing. As compared to untreated wound, the formulated spray clearly was superior, yielding a 20% more healing progress in the first 4 days alone.     

Conformation and lytic activity of eumenine mastoparan: a new antimicrobial peptide from wasp venom.

Eumenine mastoparan-AF (EMP-AF) is a novel membrane active tetradecapeptide recently isolated from the venom of solitary wasp, Anterhynchium flavomarginatum micado. It was reported previously that EMP-AF peptide presented low cytolytic activities in human erythrocytes and in RBL-2H3 mast cells. In the present work, we observed that this peptide is able to permeate anionic liposomes, and in less extension also the neutral ones. We present evidences showing that the permeation ability is well correlated with the amount of helical conformation assumed by the peptides in these environments. This peptide also showed a broad-spectrum inhibitory activity against Gram-positive and Gram-negative bacteria. The permeability of liposomes and the antibiotic effect showed a significant reduction when C-terminus was deamidated (in acidic form). The removal of the three first amino acid residues from the N-terminus rendered the peptide inactive both in liposomes and in bacteria. The results suggest that the mechanism of action involves a threshold in the accumulation of the peptide at level of cell membrane.