André Lebert

Improvement and modeling of culture parameters to enhance biomass and lipid production by the oleaginous yeast Cryptococcus curvatus grown on acetate.

The improvement of culture parameters for lipid production from acetate as carbon source was investigated using the oleaginous yeast Cryptococcus curvatus. A new pH regulation system dispensing acetate was developed for fed-batch culture and allowed obtaining nearly 80 g/L biomass within 60 h with a maximal growth rate of 0.28 h(-1). A biological model was developed from experimental data. The influence of three C/N ratios of 300, 500 and 900 were tested during a multi-phases process on lipid accumulation. The C/N ratio of 300 was reported to be the most suitable for lipid storage. No significant increase of lipids content was obtained with higher value. A maximal content of 60% DCW of lipid was obtained. The determination of fatty acids profiles of the microbial oils has confirmed that the valorization of acetate by microbial oils production was a promising perspective.

The association between Histone 3 Lysine 27 Trimethylation (H3K27me3) and prostate cancer: relationship with clinicopathological parameters

BackgroundIt is well established that genetic and epigenetic alterations are common events in prostate cancer, which may lead to aberrant expression of critical genes. The importance of epigenetic mechanisms in prostate cancer carcinogenesis is increasingly evident. In this study, the focus will be on histone modifications and the primary objectives are to map H3K27me3 marks and quantify RAR beta 2, ER alpha, SRC3, RGMA, PGR, and EZH2 gene expressions in prostate cancer tissues compared to normal tissues. In addition, a data analysis was made in connection with the clinicopathological parameters.Methods71 normal specimens and 66 cancer prostate tissues were randomly selected in order to assess the proportion of the repressive H3K27me3 mark and gene expression. H3K27me3 level was evaluated by ChIP-qPCR and mRNA expression using RT-qPCR between prostate cancer and normal tissues. Subsequently, western-blotting was performed for protein detection. The analysis of variance (ANOVA) was performed, and Tukey’s test was used to correct for multiple comparisons (p-value threshold of 0.05). The principal component analysis (PCA) and discriminant factorial analysis (DFA) were used to explore the association between H3K27me3 level and clinicopathological parameters.ResultsThe study demonstrated that H3K27me3 level was significantly enriched at the RAR beta 2, ER alpha, PGR, and RGMA promoter regions in prostate cancer tissues compared to normal tissues. After stratification by clinicopathological parameters, the H3K27me3 level was positively correlated with Gleason score, PSA levels and clinical stages for RAR beta 2, ER alpha, PGR, and RGMA. High H3K27me3 mark was significantly associated with decreased RAR beta 2, ER alpha, PGR and RGMA gene expressions in prostate cancer sample compared to the normal one. Moreover, the results showed that mRNA level of EZH2, AR and SRC3 are upregulated in prostate cancer compared to normal prostate tissues and this correlates positively with Gleason score, PSA levels and clinical stages. Obviously, these observations were confirmed by protein level using western-blot.ConclusionsThis data clearly demonstrated that H3K27me3 level correlated with aggressive tumor features. Also this study revealed that reverse correlation of RAR beta 2, ER alpha, PGR, and RGMA expressions with EZH2, SRC3, and AR expressions in prostate cancer tissues suggests that these genes are the target of EZH2. Therefore, all therapeutic strategies leading to histone demethylation with epigenetic drugs such as histone methyltransferase inhibitor may be relevant treatments against prostate cancer.

Educated consumers don't believe artificial meat is the solution to the problems with the meat industry

The production of in vitro meat by cell culture has been suggested by some scientists as one solution to address the major challenges facing our society. Firstly, consumers would like the meat industry to reduce potential discomfort of animals on modern farms, or even to avoid killing animals to eat them. Secondly, citizens would like meat producers to reduce potential environmental deterioration by livestock and finally, there is a need to reduce world hunger by increasing protein resources while the global population is predicted to grow rapidly. According to its promoters, artificial meat has a potential to make eating animals unnecessary, to reduce carbon footprint of meat production and to satisfy all the nutritional needs and desires of consumers and citizens. To check these assumptions, a total of 817 educated people (mainly scientists and students) were interviewed worldwide by internet in addition to 865 French educated people. We also interviewed 208 persons (mainly scientists) after an oral presentation regarding artificial meat. Results of the three surveys were similar, but differed between males and females. More than half of the respondents believed that “artificial meat” was feasible and realistic. However, there was no majority to think that artificial meat will be healthy and tasty, except respondents who were in favour of artificial meat. A large majority of the respondents believed that the meat industry is facing important problems related to the protection of the environment, animal welfare or inefficient meat production to feed humanity. However, respondents did not believe that artificial meat will be the solution to solve the mentioned problems with the meat industry, especially respondents who were against artificial meat. The vast majority of consumers wished to continue to eat meat even they would accept to consume less meat in a context of increasing food needs. Only a minority of respondents (from 5 to 11%) would recommend or accept to eat in vitro meat instead of meat produced from farm animals. Despite these limitations, 38 to 47% of the respondents would continue to support research on artificial meat, but a majority of them believed that artificial meat will not be accepted by consumers in the future, except for respondents who were in favour of artificial meat. We speculated that the apparent contradictory answers to this survey expressed the fact that people trust scientists who are supposed to continuously discover new technologies potentially useful in a long term future for the human beings, but people also expressed concern for their health and were not convinced that artificial meat will be tasty, safe and healthy enough to be accepted by consumers

Quantitative study of the relationships among proteolysis, lipid oxidation, structure and texture throughout the dry-cured ham process.

Temperature, salt and water contents are key processing factors in dry-cured ham production. They affect how proteolysis, lipid oxidation, structure and texture evolve, and thus determine the sensory properties and final quality of dry-cured ham. The aim of this study was to quantify the interrelationships and the time course of (i) proteolysis, (ii) lipid oxidation, (iii) five textural parameters: hardness, fragility, cohesiveness, springiness and adhesiveness and (iv) four structural parameters: fibre numbers, extracellular spaces, cross section area, and connective tissue area, during the dry-cured ham process. Applying multiple polynomial regression enabled us to build phenomenological models relating proteolysis, salt and water contents to certain textural and structural parameters investigated. A linear relationship between lipid oxidation and proteolysis was also established. All of these models and relationships, once combined with salt penetration, water migration and heat transfer models, can be used to dynamically simulate all of these phenomena throughout dry-cured ham manufacturing.

Modelling the distribution of aw, pH and ions in marinated beef meat

New beef products from low value cuts could be developed using marinating since this process has been shown to improve meat sensorial properties and shelf life. However, to optimise the process mathematical models are needed to predict evolution of the physicochemical properties that determine biochemical and structural changes. Two major works have been carried out to elaborate comprehensive models: (1) Thermodynamic models were adapted to predict water sorption isotherms and pH of beef meat tissue in presence of salts (NaCl, KCl) and organic acids (acetic, lactic, citric and ascorbic acid), (2) Fickian numerical models were set up to predict the migration of ions within meat cuts using apparent diffusivities previously estimated from 1D experiments. Simulation calculations showed reasonable agreement with measurements and can be used to investigate the effect of marinating conditions, product heterogeneity, dimension and shape.

H3K4 acetylation, H3K9 acetylation and H3K27 methylation in breast tumor molecular subtypes

AIM Here, we investigated how the St Gallen breast molecular subtypes displayed distinct histone H3 profiles. PATIENTS & METHODS 192 breast tumors divided into five St Gallen molecular subtypes (luminal A, luminal B HER2-, luminal B HER2+, HER2+ and basal-like) were evaluated for their histone H3 modifications on gene promoters. RESULTS ANOVA analysis allowed to identify specific H3 signatures according to three groups of genes: hormonal receptor genes (ERS1, ERS2, PGR), genes modifying histones (EZH2, P300, SRC3) and tumor suppressor gene (BRCA1). A similar profile inside high-risk cancers (luminal B [HER2+], HER2+ and basal-like) compared with low-risk cancers including luminal A and luminal B (HER2-) were demonstrated. CONCLUSION The H3 modifications might contribute to clarify the differences between breast cancer subtypes.

Effect of Combined Salt and Animal Fat Reductions on Physicochemical and Biochemical Changes During the Manufacture of Dry-Fermented Sausages

Reducing salt and fat contents in dry-fermented sausages could benefit consumer health. This study aimed to quantify, from an experimental design, the effects of salt and fat contents and combined salt and fat reductions on the time-course of several physicochemical (product weight loss, mean water activity and pH values) and biochemical (proteolysis, lipolysis and lipid and protein oxidations) parameters. Statistical analyses found that time, salt and fat contents had a very significant impact on weight loss and aw and that time and salt content (not fat content) had a significant impact on pH. Biochemical results indicated that proteolysis was salt-content-dependent and amplified by combined salt and fat reductions. Intensity of lipolysis was mainly dependent on fat content. Lipid and protein oxidations were more intense in higher-fat formulations. Combined salt and fat reductions in dry-fermented sausages increased acidification, weight losses and aw, leading to more proteolysis, less lipolysis and less oxidation. Sensory studies are now required to investigate consumer acceptability of these healthier sausages. However, the present results constitute a valuable set of data for helping professionals wishing to reduce salt and fat contents in dry-fermented sausages.

Comparative Effects of Soy Phytoestrogens and 17β-Estradiol on DNA Methylation of a Panel of 24 Genes in Prostate Cancer Cell Lines

Major phytoestrogens genistein and daidzein have been reported to have the ability to reverse DNA methylation in cancer cell lines. The mechanism by which genistein and daidzein have an inhibiting action on DNA methylation is not well understood. The aim of this study was to investigate the effects of soy phytoestrogens and the natural estrogen 17β-estradiol (E2) to determine whether one of the estrogen receptors is mobilized for the action of these compounds on DNA methylation. We also made a comparative study with a DNA methylation inhibitor (5-azacytidine) and a DNA methylation activator (budesonide). Three prostate cell lines, PC-3, DU-145, and LNCaP, were treated with 40 μM genistein, 110 μM daidzein, 2 μM budesonide, 2 μM 5-azacytidine, and 10 μM E2. In these 3 human prostate cancer cell lines, we performed methylation quantification using methyl-profiler-DNA-methylation analysis. Soy phytoestrogens and E2 induced a demethylation of all the promoter regions studied except for those that were unmethylated in control cells. Our results showed that E2 induces, like soy phytoestrogen, a decrease in DNA methylation in prostate cancer cell lines. This action may be mediated through ERβ.

Building phenomenological models that relate proteolysis in pork muscles to temperature, water and salt content

Throughout dry-cured ham production, salt and water content, pH and temperature are key factors affecting proteolysis, one of the main biochemical processes influencing sensory properties and final quality of the product. The aim of this study was to quantify the effect of these variables (except pH) on the time course of proteolysis in laboratory-prepared pork meat samples. Based on a Doehlert design, samples of five different types of pork muscle were prepared, salted, dried and placed at different temperatures, and sampled at different times for quantification of proteolysis. Statistical analysis of the experimental results showed that the proteolysis index (PI) was correlated positively with temperature and water content, but negatively with salt content. Applying response surface methodology and multiple linear regressions enabled us to build phenomenological models relating PI to water and salt content, and to temperature. These models could then be integrated into a 3D numerical ham model, coupling salt and water transfers to proteolysis.

Proof of concept for biorefinery approach aiming at two bioenergy production compartments, hydrogen and biodiesel, coupled by an external membrane

ABSTRACT A biorefinery is a facility that integrates biomass conversion processes and equipment to produce fuels, power and chemicals from biomass. This concept is applied here to hydrogen production by anaerobic fermentation. Its biological production is increasingly perceived as a potential pathway for developing renewable sources of energy, due to hydrogens high energy content (142 kJ g−1) and the absence of harmful emissions during utilization in a hydrogen fuel cell. The main secondary metabolites produced during dark fermentation (volatile fatty acids, VFAs) are building blocks and can also serve as an alternate carbon source for lipid production from oleaginous yeast strains for biodiesel production. The concept proposed here is the coupling of two main compartments. In the first one, lignocellulosic biomass is transformed by dark fermentation into hydrogen and VFAs. The medium used in the first compartment is transferred via an immersed membrane bioreactor to the second compartment where the production of single-cell oil with oleaginous yeast occurs using VFAs as carbon source. This study aims at presenting the feasibility of this bioprocess, through hydrogen production from glucose followed by lipid production by the oleaginous yeast Cryptococcus curvatus grown on the VFA-enriched supernatant resulting from the dark fermentation step.