Diversity and biological activities of the bacterial community associated with the marine sponge Phorbas tenacior (Porifera, Demospongiae).

UNLABELLED: The diversity of the cultivable microbiota of the marine sponge Phorbas tenacior frequently found in the Mediterranean Sea was investigated, and its potential as a source of antimicrobial, antioxidant and antiplasmodial compounds was evaluated. The cultivable bacterial community was studied by isolation, cultivation and 16S rRNA gene sequencing. Twenty-three bacterial strains were isolated and identified in the Proteobacteria (α or γ classes) and Actinobacteria phyla. Furthermore, three different bacterial morphotypes localized extracellularly within the sponge tissues were revealed by microscopic observations. Bacterial strains were assigned to seven different genera, namely Vibrio, Photobacterium, Shewanella, Pseudomonas, Ruegeria, Pseudovibrio and Citricoccus. The strains affiliated to the same genus were differentiated according to their genetic dissimilarities using random amplified polymorphic DNA (RAPD) analyses. Eleven bacterial strains were selected for evaluation of their bioactivities. Three isolates Pseudovibrio P1Ma4, Vibrio P1MaNal1 and Citricoccus P1S7 revealed antimicrobial activity; Citricoccus P1S7 and Vibrio P1MaNal1 isolates also exhibited antiplasmodial activity, while two Vibrio isolates P1Ma8 and P1Ma5 displayed antioxidant activity. These data confirmed the importance of Proteobacteria and Actinobacteria associated with marine sponges as a reservoir of bioactive compounds. SIGNIFICANCE AND IMPACT OF THE STUDY: This study presents the first report on the diversity of the cultivable bacteria associated with the marine sponge Phorbas tenacior, frequently found in the Mediterranean Sea. Evaluation of the antiplasmodial, antimicrobial and antioxidant activities of the isolates has been investigated and allowed to select bacterial strains, confirming the importance of Proteobacteria and Actinobacteria as sources of bioactive compounds.

Ponericins, new antibacterial and insecticidal peptides from the venom of the ant Pachycondyla goeldii.

The antimicrobial, insecticidal, and hemolytic properties of peptides isolated from the venom of the predatory ant Pachycondyla goeldii, a member of the subfamily Ponerinae, were investigated. Fifteen novel peptides, named ponericins, exhibiting antibacterial and insecticidal properties were purified, and their amino acid sequences were characterized. According to their primary structure similarities, they can be classified into three families: ponericin G, W, and L. Ponericins share high sequence similarities with known peptides: ponericins G with cecropin-like peptides, ponericins W with gaegurins and melittin, and ponericins L with dermaseptins. Ten peptides were synthesized for further analysis. Their antimicrobial activities against Gram-positive and Gram-negative bacteria strains were analyzed together with their insecticidal activities against cricket larvae and their hemolytic activities. Interestingly, within each of the three families, several peptides present differences in their biological activities. The comparison of the structural features of ponericins with those of well-studied peptides suggests that the ponericins may adopt an amphipathic alpha-helical structure in polar environments, such as cell membranes. In the venom, the estimated peptide concentrations appear to be compatible with an antibacterial activity in vivo. This suggests that in the ant colony, the peptides exhibit a defensive role against microbial pathogens arising from prey introduction and/or ingestion.

New lipids from the tunicate Cystodytes cf. dellechiajei, as PLA2 inhibitors.

Cystodytes cf. dellechiajei collected off Djerba furnished new lipids, sphingosines 1, as inhibitors of phospholipase A2, along with inactive homologous ceramides 2. Structures were determined by spectroscopic methods and chemical transformations.

Characterization of a novel elastase inhibitor from a fan coral.

An acidic hydromethanolic extract of the tropical gorgonian Melithea cf. stormii exhibited anti-elastase activity. From the polypeptidic mixture we isolated and purified to homogeneity a protein with a molecular mass determined at 21,159 Da by Maldi/Tof mass spectrometric analysis. The novel protein of marine invertebrate origin strongly inhibited amidolysis of Suc(Ala) 3pNA by porcine pancreatic elastase (PPE) and was labelled iela melst. The N-terminal aminoacid sequence of its 39-first residues revealed the characteristics of a non-classical Kazal-type domain. Iela melst behaved as a reversible tight-binding inhibitor of PPE. The competitive inhibition followed Cha's mechanism A with an equilibrium dissociation constant, Ki, calculated as 1.5 x 10(-9) M.

Sesquiterpene quinones as immunomodulating agents.

The influence of sesquiterpene quinones and of a sesquiterpene hydroquinone, isolated from the sponge Smenospongia sp. on normal and tumour cells, was investigated. Most showed cytotoxic effects on L1210 leukemia cells. However, their activity on normal cells, such as murine spleen lymphocytes and human peripheral lymphocytes, revealed different behaviours: some of them inhibited, while other enhanced mitogen-stimulated lymphocyte proliferation. These biological studies revealed products modulating immune responses.

[Assay of chorionic gonadotrophin, follicle-stimulating hormone and alpha-fetoprotein in the efferent blood in germinal tumors of the testis]. / Dosage de la gonadotrophine chorionique, de la folliculostimuline et de l'alpha-foetoprotéine dans le sang efférent des tumeurs germinales du testicule.

Assays of human chorionic gonadotrophin (hCG), follicle-stimulating hormone (FSH) and alpha-foetoprotein were performed in peripheral blood and spermatic vein in 73 cases of testicular germ cell tumors. This study showed that the detection sensitivity of hCG is up to 40 times higher in the efferent blood of the tumor than in peripheral blood and that the drop in FSH concentrations often precedes a trophoblastic transformation. These results are of particular interest in the search for a minor trophoblastic or embryonic component. As a result, we propose a new strategy leading to a more efficient diagnosis and an adequate therapy.

A solid-phase luminescent immunoassay for human chorionic gonadotropin using Pholas dactylus bioluminescence.

A solid-phase luminescent immunoassay (LIA), based on the light emission produced as a result of the oxidation of Pholas dactylus luciferin by horseradish peroxidase (HRP) in the presence of molecular oxygen, was developed for human chorionic gonadotropin (hCG). The light emitted in the presence of diethyldithiocarbamate permitted the detection of 0.1 fmol HRP. HRP retained most of its light-emitting capacity after coupling with purified anti-hCG antibody by glutaraldehyde. The LIA involved immobilization of the antigen in plastic tubes coated with purified anti-hCG antibody and detection of the immunocomplex by light emission in the presence of Pholas luciferin. Light emission was linear for antigen concentration within the range 0.5-100 ng/ml. LIA correlates reasonably well with RIA and has a comparable sensitivity (0.5 ng hCG/ml).