Isolation, characterization and biological evaluation of jellyfish collagen for use in biomedical applications

Fibrillar collagens are the more abundant extracellular proteins. They form a metazoan-specific family, and are highly conserved from sponge to human. Their structural and physiological properties have been successfully used in the food, cosmetic, and pharmaceutical industries. On the other hand, the increase of jellyfish has led us to consider this marine animal as a natural product for food and medicine. Here, we have tested different Mediterranean jellyfish species in order to investigate the economic potential of their collagens. We have studied different methods of collagen purification (tissues and experimental procedures). The best collagen yield was obtained using Rhizostoma pulmo oral arms and the pepsin extraction method (2-10 mg collagen/g of wet tissue). Although a significant yield was obtained with Cotylorhiza tuberculata (0.45 mg/g), R. pulmo was used for further experiments, this jellyfish being considered as harmless to humans and being an abundant source of material. Then, we compared the biological properties of R. pulmo collagen with mammalian fibrillar collagens in cell cytotoxicity assays and cell adhesion. There was no statistical difference in cytotoxicity (p > 0.05) between R. pulmo collagen and rat type I collagen. However, since heparin inhibits cell adhesion to jellyfish-native collagen by 55%, the main difference is that heparan sulfate proteoglycans could be preferentially involved in fibroblast and osteoblast adhesion to jellyfish collagens. Our data confirm the broad harmlessness of jellyfish collagens, and their biological effect on human cells that are similar to that of mammalian type I collagen. Given the bioavailability of jellyfish collagen and its biological properties, this marine material is thus a good candidate for replacing bovine or human collagens in selected biomedical applications.     

Screening tuber-bearingSolanum spp. for resistance to soft rot caused byErwinia carotovora ssp.atroseptica (van Hall) Dye

Summary Soft rot caused by Erwinia carotovora ssp. atroseptica is a major disease of stored potatoes. Since varietal resistance can contribute to control, the work reported was designed to find new sources of resistance among related tuber-bearing Solanum spp. True seeds were imported from two international collections and families were screened for resistance to tuber soft rot. Forty-eight resistant clones were found in 21 out of 100 accessions. These clones will be used in breeding programmes at the diploid or tetraploid level.     

Molecular analysis of the sex chromosomes of the platyfish Xiphophorus maculatus: Towards the identification of a new type of master sexual regulator in vertebrates

In contrast to mammals and birds, fish display an amazing diversity of genetic sex determination systems, with frequent changes during evolution possibly associated with the emergence of new sex chromosomes and sex‐determining genes. To better understand the molecular and evolutionary mechanisms driving this diversity, several fish models are studied in parallel. Besides the medaka (Oryzias latipes Temminck and Schlegel, 1846) for which the master sex‐determination gene has been identified, one of the most advanced models for studying sex determination is the Southern platyfish (Xiphophorus maculatus, Günther 1966). Xiphophorus maculatus belongs to the Poeciliids, a family of live‐bearing freshwater fish, including platyfish, swordtails and guppies that perfectly illustrates the diversity of genetic sex‐determination mechanisms observed in teleosts. For X. maculatus, bacterial artificial chromosome contigs covering the sex‐determination region of the X and Y sex chromosomes have been constructed. Initial molecular analysis demonstrated that the sex‐determination region is very unstable and frequently undergoes duplications, deletions, inversions and other rearrangements. Eleven gene candidates linked to the master sex‐determining gene have been identified, some of them corresponding to pseudogenes. All putative genes are present on both the X and the Y chromosomes, suggesting a poor degree of differentiation and a young evolutionary age for platyfish sex chromosomes. When compared with other fish and tetrapod genomes, syntenies were detected only with autosomes. This observation supports an independent origin of sex chromosomes, not only in different vertebrate lineages but also between different fish species.     

Quercetin exhibits a specific fluorescence in cellular milieu: a valuable tool for the study of its intracellular distribution

The elaboration of novel techniques for flavonoid intracellular tracing would elucidate the compounds' absorption and bioavailability and assist molecular and pharmacological approaches, as they are promising candidates for drug development. This study exploited the properties of quercetin (3,3',4',5,7-pentahydroxyflavone), found in high concentrations in the majority of edible plants. Through the use of UV-vis spectroscopy, confocal microscopy, and HPLC-ESI-MS, native quercetin, at physiologically relevant concentrations, was found to exhibit a specific fluorescence (488 nmex/500-540 nmem) upon internalization. This fluorescence shift is due to a non-covalent binding to intracellular targets (probably proteins) and compatible with the settings applied in confocal microscopy. This property provides a valuable, selective alternative technique for quercetin tracing in cellular systems, permitting the quantitative evaluation of its transit at pharmacologically relevant concentrations and the validation of a number of already described molecular functions.     

Assessment of anthocyanins in grape (Vitis vinifera L.) berries using a noninvasive chlorophyll fluorescence method

Anthocyanins (Anths) in grape (Vitis vinifera L.) berries harvested at véraison from Pinot Noir and Pinot Meunier cultivars were assessed nondestructively by measuring chlorophyll fluorescence (ChlF) excitation spectra. With increasing Anth content, less excitation light was transmitted to the deeper Chl layers, and thus the ChlF signal decreased proportionally. By applying Beer-Lambert's law, the logarithm of the ratio between the fluorescence excitation spectra (log FER) from a green and a red berry gave the in vivo absorption spectrum of Anths, which peaked at about 540 nm. Absolute quantitative nondestructive determination of Anths for each berry was obtained by the log FER calculated for two excitation wavelengths, 540 and 635 nm (absorbed and not-absorbed by Anths, respectively) of ChlF at 685 nm. Over a range of skin colors going from green to purple, the relationship between the log [ChlF(635)/ChlF(540)] and the Anth concentration of berry extracts was fairly well fitted (r 2 = 0.92) using a power function. Reflectance spectra on the same berry samples were also measured, and Anth reflectance indices, which were originally developed for apples and table grapes, were derived. The log FER Anth index was superior to the reflectance-ratio-based index, but was as good as the color index for red grapes (CIRG) calculated from the whole visible reflectance spectrum. The proposed log FER method, applied by means of suitable portable devices, may represent a new, rapid, and noninvasive tool for the assessment of grape phenolic maturity in vineyards.     

Gas diffusion in a silty-clay soil: experimental study on an undisturbed soil core and simulation in its three-dimensional reconstruction

Transport of gas in soil depends on the paths available through the porous system. We determined the rate of diffusion of air through a core of silty-clay soil experimentally. After the experiment, the core was impregnated with resin and sectioned at 100 μm. From the images of the sections, the porous structure was reconstructed in three dimensions with a 100-μm resolution and gas diffusion was simulated in it. We computed the self-diffusion to describe gas diffusion. The experiment and simulation were compared using tortuosity, which is the ratio between the self-diffusion coefficient calculated in air and the coefficient calculated in the reconstructed sample. The results showed that the experimentally measured tortuosity (2.3) and the numerically calculated tortuosity (1.75) were similar. This suggests that the self-diffusion propagator is useful for simulating self-diffusion in a numerical three-dimensional reconstructed sample and that the scale chosen for the reconstruction of the sample (100 μm) was suitable for this particular soil. Résumé Les propriétés de transfert en phase gazeuse des sols ont étéétudiées sur un sol limono-argileux. A l’issue de l’expérience, l’échantillon a été imprégné avec une résine polyester puis sectionné en coupes sériées. A l’aide des images numérisées des coupes, l’échantillon a été reconstruit en trois dimensions. Nous avons ensuite simulé le processus de diffusion gazeuse dans l’échantillon reconstruit à l’aide du propagateur de diffusion. Expérience et simulation ont été comparées à l’aide de la tortuosité, rapport entre le coefficient de diffusion gazeuse dans l’air et celui dans le sol. Les résultats montrent que la tortuosité mesurée expérimentalement (2,3) et la tortuosité calculée numériquement (1,75) sont proches. Ceci prouve que l’utilisation du propagateur de diffusion est justifiée pour la simulation du processus de self-diffusion dans un échantillon tridimensionnel reconstruit et que l’échelle choisie pour la reconstruction (100 μm) s’avère pertinente pour l’étude de la diffusion gazeuse dans ce sol.     

Combined effects of temperature and salinity on development and survival of Atlantic halibut larvae

The effects of different combinations of temperature and salinity on development and survival of Atlantic halibut, Hippoglossus hippoglossus (L.), larvae were studied in two experiments. In the period from 57 to 120 d° post hatching, approximately 38% of the larvae died: in both experiments, mortality was significantly related to temperature, but there was no relationship to salinity.Cumulative, chronic mortality during the yolk-sac stage (until 210 d°) was related to salinity. High mortality was observed in both experiments when high salinity (>34%) was combined with incubation at either high (9 °C) or low (3 °C) temperature. The development of head lesions was significantly related to temperature, and for larvae kept at high salinity, increased mortality may have been a result of salinity stress in the injured larvae.Abnormal development of the caudal notochord, sometimes resulting in a 90-degree bend of the tail, occurred during incubation of early yolk-sac larvae in high-salinity water. The occurrence of larvae with locked jaws, and larvae with oedema in the yolk-sac sinus and pericardium, was significantly related to temperature. © Rapid Science Ltd. 1998