Source localization with vector sensor array during the makai experiment

Vector sensors measure both the acoustic pressure and the three components of particle velocity. Because of this, a vector sensor array (VSA) has the advantage of being able to provide substantially higher directivity with a much smaller aperture than an array of traditional scalar (pressure only) hydrophones. Although several, most of them theoretic, works were published from early nineties, only in the last years due to improvements and availability of vector sensor technology, the interest on field experiments with VSA increased in the scientific community. During the Makai Experiment, that took place off the coast of Kauai I., Hawaii, in September 2005, real data were collected with a 4 element vertical VSA. These data will be discussed in the present paper. The acoustic signals were emitted from a near source (low frequency ship noise) and two high frequency controlled acoustic sources located within a range of 2km from the VSA. The advantages of the VSA over traditional scalar hydrophone arrays in source localization will be addressed using conventional beamforming.

Co-localization of GnRH ligands and their receptors in the European sea bass, Dicentrarchus labrax

The migration of the hypophysiotropic GnRH (GnRH-I) neurons during early development is a crucial step in establishing a normally functioning reproductive system in all vertebrates. These neurons derive from progenitor cells in the olfactory placode and subsequently migrate to their final position in the ventral forebrain, where they mediate hypophysiotropic control over Lh. We use zebrafish as a model to investigate the path and the factors that mediate the migration of the GnRH-I neurons during early development. A transgenic line of zebrafish, in which GnRH- I neurons specifically express a reporter gene (GFP) has been developed in our lab. This was achieved by integrating a GnRH-I promoter/GFP reporter transgene into the zebrafish genome. The resulting transgenic line allows us to track the route of the GnRH-I neuronal migration in real time and in vivo. We have used this line to conduct time lapse imaging to ascertain the exact migrational path and the final position in the ventral forebrain of the GnRH-I neurons.

Searching biocompounds in marine natural extracts with potential use in tumor prevention and treatment

Cancer is a multistage process characterized by three stages: initiation, promotion and progression; and is one of the major killers worldwide. Oxidative stress acts as initiator in tumorigenesis; chronic inflammation promotes cancer; and apoptosis inactivation is an issue in cancer progression. In this study, it was investigated the antioxidant, antiinflammatory and antitumor properties of hexane, ether, chloroform, methanol and water extracts of five species of halophytes: A. macrostachyum, P. coronopus, J. acutus, C. edulis and A. halimus. Antioxidant activity was assessed by DPPH• and ABTS•+ methods, and the total phenolics content (TPC) was evaluated by the Folin-Ciocalteau method. The anti-inflammatory activity of the extracts was determined by the Griess method, and by evaluating the inhibition of NO production in LPS-stimulated RAW- 264.7 macrophages. The cytotoxic activity of the extracts against HepG2 and THP1 cell lines was estimated by the MTT assay, and the results obtained were further compared with the S17 non-tumor cell line. The induction of apoptosis of J. acutus ether extract was assessed by DAPI staining. The highest antioxidant activities was observed in C. edulis methanol and the J. acutus ether extracts against the DPPH• radical; and J. acutus ether and A. halimus ether extracts against the ABTS•+ radical. The methanol extracts of C. edulis and P. coronopus, and the ether extract of J. acutus revealed a high TPC. Generally the antioxidant activity had no correlation with the TPC. The A. halimus chloroform and P. coronopus hexane extracts demonstrated ability to reduce NO production in macrophages (> 50%), revealing their anti-inflammatory capacity. The ether extract of J. acutus showed high cytotoxicity against HepG2 cancer cells, with reduced cellular viability even at the lowest concentrations. This outcome was significantly lower than the obtained with the non-tumor cells (S17). This result was complemented by the induction of apoptosis.