Biomedical subjects

Yves Le Gal

Publications and source records attributed to Yves Le Gal.

5 recordsLinked to original sources

PubMed2005

Fish and shellfish upgrading, traceability.

Recognition of the limited biological resources and the increasing environmental pollution has emphasised the need for better utilisation of by-products from the fisheries. Currently, the seafood industry is dependent on the processing of the few selected fish and shellfish species that are highly popular with consumers but, from economic and nutritional points of view, it is essential to utilise the entire catch. In this review, we will focus on recent developments and innovations in the field of underutilised marine species and marine by-product upgrading and, more precisely, on two aspects of the bioconversion of wastes from marine organisms, i.e. extraction of enzymes and preparation of protein hydrolysates. We will deal with the question of accurate determination of fish species at the various steps of processing. Methods of genetic identification applicable to fresh fish samples and to derived products will be described.

Animals↗

PubMed2004

Amino acid utilization by Chlamydomonas reinhardtii: specific study of histidine.

Phytoplankton live in fluctuating environments where many factors such as grazing pressure, sinking, light availability, nutrient uptake and turnover influence the distribution of phytoplankton in time and space. The purpose of this study was to investigate if under conditions of depletion of inorganic nitrogen, as recorded in summer in naturals waters, phytoplanktonic species have the capability of using organic nitrogen sources, including free or combined amino acids, in addition to inorganic nitrogen. The study has focussed on histidine, the degradation of which yielding potentially three nitrogen atoms for each molecule of histidine. Chlamydomonas reinhardtii (CCAP 11/32A) was cultivated axenically with two different sources of nitrogen (histidine and/or ammonium). In the presence of histidine as sole source of nitrogen, cell growth was comparable to that observed with the same concentration of nitrogen in ammonium form. In the presence of both histidine and ammonium, histidine degradation was observed only when the concentration of ammonium was depleted. Under these conditions, the first two enzymes of histidine degradation pathway, histidase (EC 4.3.1.3) and urocanase (EC 4.2.1.49) were produced and were co-ordinately regulated. Histidase activity was also controlled by succinate and glutamate as carbon sources. Histidase was purified 1018-fold and partially characterized. The molecular weight of the native enzyme was estimated to 152.4 kDa corresponding to four subunits of 38.1 kDa. The enzyme did not exhibit classical Michaelis-Menten kinetics but showed a relationship between the rate of catalysis (V) and the concentration of substrate (S), characteristic of negative allosteric behavior. A Hill coefficient of 4 was measured for histidine concentrations higher than 20.5 mM.

Amino Acids↗

PubMed2003

Seasonal variation of antifouling activities of marine algae from the Brittany coast (France).

The antifouling activity of extracts (aqueous, ethanol, and dichloromethane) of 9 marine macroalgae against bacteria, fungi, diatoms, macroalgal spores, mussel phenoloxidase activity, and barnacle cypris larvae has been investigated in relation to season in bimonthly samples from the Bay of Concarneau (France). Of the extracts tested, 48.2% were active against at least one of the fouling organisms, and of these extracts, 31.2% were seasonally active with a peak of activity in summer corresponding to maximal values for water temperature, light intensity, and fouling pressure, and 17% were active throughout the year. This seasonal activity may be adaptive as it coincides with maximal fouling pressure in the Bay of Concarneau. Dichloromethane extracts of Rhodophyceae were the most active in the antifouling assays.

Animals↗

PubMed2002

Antibacterial, antifungal and cytotoxic activities of extracts from fish epidermis and epidermal mucus.

Annual discards from the world fisheries are estimated to be approximately 20 million metric tonnes (25%) per year. The main objective of this work is to increase the utilisation of by-products (notably skin) from fish species in order to isolate new biologically active compounds. This study presents the results of a screening program for antifungal, antibacterial and cytotoxic activities in epidermal mucus and epidermis extracts of thirteen fish species that are commonly caught in North Atlantic waters and generate an important amount of fish waste. Antimicrobial assays used five Gram-positive bacteria five Gram-negative bacteria and five fungi. Of the 78 extracts tested, 15 showed antibacterial and/or antifungal activities. None of the aqueous fractions were active. One third of the active extracts were ethanolic fractions and three fourth of extracts were dichloromethane fractions. One third of the active fractions were of epidermal origin and the remaining came from mucus fractions. The high levels of inhibitory activity and no apparent toxicity against mouse fibroblasts of extracts of Pollachius virens (CH(3)CH(2)OH/epidermis), Labrus bergylta (CH(2)Cl(2)/mucus), Platichthys flesus (CH(3)CH(2)OH/mucus), Solea solea (CH(2)Cl(2)/mucus) and Scophtalamus rhombus (CH(2)Cl(2)/mucus) suggest they may have potential as novel active therapeutic agents.

Animals↗

PubMedDate not supplied

Distribution and potential role of cytosolic water-soluble phosphodiesters in fish.

The distribution of water-soluble phosphodiesters (WSPDEs) visible by nuclear magnetic resonance (NMR) in some intact tissues of rainbow trout (Oncorhynchus mykiss walbaum) and in perchloric extracts after partial purification was examined by (31)P NMR spectroscopy. The compounds of interest were serine ethanolamine phosphate (SEP), threonine ethanolamine phosphate (TEP), glycerophosphorylcholine (GPC), and glycerophosphorylethanolamine (GPE). TEP and SEP were mostly accumulated in the heart and less accumulated in the kidney of intact trout. After the extraction procedure, two additional minor resonances were visible and identified as GPC and GPE. The liver of trout contained large amounts of GPE. Similar investigations were conducted by (31)P NMR on hearts and kidneys of two elasmobranchs (Scyliorhinus canicula, Raja clavata) and four teleosts (Anguilla anguilla, Sparus auratus, Dicentrarchus labrax, Scophtlhalmus maximus); comparison with the trout data showed striking interspecies differences in the identity of WSPDEs. All teleosts, except eel and turbot, accumulated predominantly TEP. However, in elasmobranchs, first GPC and then GPE were the major compounds. Whatever the studied species, the relative abundances in the heart and kidney were similar. In the last two decades, two hypotheses were proposed to explain the occurrence of high levels of cytosoluble phosphodiesters: these compounds may constitute an index of phospholipid catabolism or a protective mechanism through which phospholipid levels are kept high. To test them and elucidate the role of these compounds in membrane phospholipid regulation in fish, we investigated the effects of two physiological stresses, that is, seawater adaptation and induced myocardial ischemia, on trout cytosolic phosphodiester levels. A 32.5-min ischemic stress caused no effect on SEP and TEP levels. On the contrary, significant osmotic stress induced changes in the PDEs levels: 2 d after transfer from freshwater to seawater or from seawater to freshwater, both tissues displayed a transient decrease of TEP; however, a 2-d stay in seawater after transfer from freshwater caused a rise in SEP concentration, whereas a 2-d stay in freshwater after transfer decreased SEP level. In conclusion, our experiments suggest a relationship between the high levels of cytosoluble phosphodiesters observed in some fish tissues and resistance to stress.

Adaptation, Physiological↗