Summary Differential display was used to isolate early ethylene‐regulated genes from late immature green tomato fruit in order to obtain a broader understanding of the molecular basis by which ethylene coordinates the ripening process. Nineteen novel ethylene‐responsive (ER) cDNA clones were isolated that fell into three classes: (i) ethylene up‐regulated (ii) ethylene down‐regulated, and (iii) transiently induced. Expression analysis revealed that ethylene‐dependent changes in mRNA accumulation occurred rapidly (15 min) for most of the ER clones. The predicted proteins encoded by the ER genes are putatively involved in processes as diverse as primary metabolism, hormone signalling and stress responses. Although a number of the isolated ER clones correspond to genes already documented in other species, their responsiveness to ethylene is described here for the first time. Among the ER clones sharing high homology with regulatory genes, ER43, a putative GTP‐binding protein, and ER50, a CTR1‐like clone, are potentially involved in signal transduction. ER24 is homologous to the multi‐protein bridging factor MBF1 involved in transcriptional activation, and finally, two clones are homologous to genes involved in post‐transcriptional regulation: ER49, a putative translational elongation factor, and ER68, a mRNA helicase‐like gene. Six ER clones correspond to as yet unidentified genes. The expression studies indicated that all the ER genes are ripening‐regulated, and, depending on the clone, show changes in transcript accumulation either at the breaker, turning, or red stage. Analysis of transcript accumulation in different organs indicated a strong bias towards expression in the fruit for many of the clones. The potential roles for some of the ER clones in propagating the ethylene response and regulating fruit ripening are discussed.

Codium fragile and Chondrus crispus are, respectively, green and red seaweeds which are abundant along the North Atlantic coasts. We investigated the chemical composition and antiviral activity of enzymatic extracts of C. fragile (CF) and C. crispus (CC). On a dry weight basis, CF consisted of 11% protein, 31% neutral sugars, 0.8% sulfate, 0.6% uronic acids, and 49% ash, while CC contained 27% protein, 28% neutral sugars, 17% sulfate, 1.8% uronic acids, and 25% ash. Enzyme-assisted hydrolysis improved the extraction efficiency of bioactive materials. Commercial proteases and carbohydrases significantly improved (p ≤ 0.001) biomass yield (40%–70% dry matter) as compared to aqueous extraction (20%–25% dry matter). Moreover, enzymatic hydrolysis enhanced the recovery of protein, neutral sugars, uronic acids, and sulfates. The enzymatic hydrolysates exhibited significant activity against Herpes simplex virus (HSV-1) with EC50 of 77.6–126.8 μg/mL for CC and 36.5–41.3 μg/mL for CF, at a multiplicity of infection (MOI) of 0.001 ID50/cells without cytotoxity (1–200 μg/mL). The extracts obtained from proteases (P1) and carbohydrases (C3) were also effective at higher virus MOI of 0.01 ID50/cells without cytotoxity. Taken together, these results indicate the potential application of enzymatic hydrolysates of C. fragile and C. crispus in functional food and antiviral drug discovery.

International audienc

International audienc

Mortality of oysters Crassostrea gigas occurred along the coasts of France during summer 2008, causing a serious crisis in French oyster production. During spring to summer 2008, 5 groups of 1-yr old oysters of different origins and ploidy levels deployed in the Thau lagoon (France) were sampled for biometrical and biochemical analyses; environmental parameters were monitored in the same area. Mortality occurred in 2 episodes: 13 May to 10 June and 24 June to 9 July. Wild-collected oysters showed mortality sooner than other groups but total overall mortality was 85% in all groups. Mortality occurred when seawater temperature was >19°C during the reproductive season when energetic reserves of oysters were at their lowest. Energy reserve levels and mortality in oysters seemed to be independent of reproductive effort, and most likely reflected an unusual deficit in phytoplankton. The level of bacterial fatty acids in oysters increased markedly before the second mortality event, probably indicating an enhancement of the microbial loop or decomposition processes. At the same time, unsaturation of oyster fatty acids decreased, suggesting a diet change, acclimatization to increasing temperature or, most likely, oxidative damage due to an enhanced production of reactive oxygen species, which are often associated with stressful situations. Wild-collected and hatchery-produced oysters, which exhibited different mortality patterns, showed persistent differences in fatty acid (20:5n-3 and 22:6n-3) content in their membrane, despite the fact that they were reared in the same environment. Mortality started when fatty acid 20:4n-6 content increased to ~3% in the polar lipids, suggesting that this ratio could make a useful indicator of mortality risk. Finally, the 2008 mortality event coincided with a nationwide increase of ~1.5°C in winter seawater temperature, which may impact the oyster and its pathogens. KEY WORDS: Bivalves · Energetic reserve · Environment · Fatty acid · Summer mortality · Trophic signatures · TemperatureResale or republication not permitted without written consent of the publisher Mar Ecol Prog Ser 401: 129-146, 2010 their relative importance, a model was recently proposed to explain the summer mortality of the Pacific oyster Crassostrea gigas in France, incorporating the animal, its pathogens and the environment (Samain & McCombie 2008).According to this model, mortalities occur when seawater temperature exceeds 19 to 20°C during the spring-summer period. Once temperatures exceed this threshold, oysters usually reach the pre-spawning stage characterized by a negative energy budget: energetic resources attain their lowest level whereas energy demand and reproductive effort are at their highest (Soletchnik et al. 1997, Berthelin et al. 2000, Delaporte et al. 2006, Samain & McCombie 2008. Oyster haemocytes, circulating cells that play an important role in defence, also show their lowest performance at this time (Delaporte et al. 2006, Gagnaire et al. 2006, Li et al. 2009). Finally, although ve...

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Polysaccharides, lipids and amino acid profiles were investigated to understand the nutritional value of Caulerpa racemosa and Ulva fasciata from the Philippines. The results revealed that both species contain high amounts of proteins (8.8–19.9% for C. racemosa and 8.0–11.1% for U. fasciata). The portions of the total amino acids that were essential amino acids (EAAs) (45.28 ± 0.12% for C. racemosa and 42.17 ± 0.12% for U. fasciata) out were comparable to FAO/WHO requirements. Leucine, valine, isoleucine, and lysine are the dominant EAAs in C. racemosa, while leucine, valine, lysine, and phenylalanine are those in U. fasciata. The fatty acid profiles are dominated by monounsaturated fatty acids and polyunsaturated fatty acids in C. racemosa (56.2%), while saturated fatty acids (72.1%) are dominant in U. fasciata. High C18/C20 polyunsaturated fatty acid ratios were recorded in both species. Mineral contents for both seaweeds were within levels considered safe for functional foods. Total pigment content of C. racemosa (140.84 mg/g dw) was almost 20 times higher than that of U. fasciata (7.54 mg/g dw). Hot water extract (HWE) from C. racemosa showed in vitro antiherpetic activity without cytotoxicity. Nutritional characteristics confirmed that C. racemosa could be potentially used as a nutritious and functional food items for human consumption.

We report the isolation by differential display of a novel tomato ethylene-responsive cDNA, designated ER5. RT-PCR analysis of ER5 expression revealed an early (15 min) and transient induction by ethylene in tomato fruit, leaves and roots. ER5 mRNA accumulated during 2 h of ethylene treatment and thereafter underwent a dramatic decline leading to undetectable expression after 5 h of treatment. The full-length cDNA clone of 748 bp was obtained and DNA sequence analysis showed strong homologies to members of the atypical hydrophobic group of the LEA protein family. The predicted amino acid sequence shows 67%, 64%, 64%, and 61% sequence identity with the tomato Lemmi9, soybean D95-4, cotton Lea14-A, and resurrection plant pcC27-45 gene products, respectively. As with the other members of this group, ER5 encodes a predominantly hydrophobic protein. Prolonged drought stress stimulates ER5 expression in leaves and roots, while ABA induction of this ethylene-responsive clone is confined to the leaves. The use of 1-MCP, an inhibitor of ethylene action, indicates that the drought induction of ER5 is ethylene-mediated in tomato roots. Finally, wounding stimulates ER5 mRNA accumulation in leaves and roots. Among the Lea gene family this novel clone is the first to display an ethylene-regulated expression.