Roles of structural phenylpropanoids in forage cell wall digestion

Phenolic constituents (lignins and phenolic acids) and carbohydrates are assembled in a tight architecture which differs according to the plant species. During cell wall digestion, the hydrolysis kinetics differ between carbohydrates and seem to depend chiefly on the content and organisation of tissue phenolics. Among the phenylpropanoids, ferulic acid is released more quickly than p-coumaric acid. Lignins remain largely in the cell walls. They also undergo transformations, chiefly solubilisation as lignin-carbohydrate complexes. The limiting effect of lignins on cell wall degradation increases with increasing content. However, their effect on degradation might also depend on qualitative factors such as lignin structure and polymer organisation in walls and tissues. When various grasses (normal and selected genotypes), or grasses and legumes are compared, correlations between certain factors such as lignin uncondensed fraction, syringyl units or phenolic acids contents and cell wall degradation emerge but not clear causal relationship has been shown. Nonetheless, other structural characteristics, related to the alkali reactivity of lignins, seem to have a stronger influence on cell wall degradation. Phenylpropanoids seem to act mainly as a physical and (bio)chemical barrier to the action of the microbial enzymes. In addition, their reactivity as phenolic compounds and their hydrophobicity seem to play a role. Digestion is not limited only by phenolics. The factors that limit glycanolysis—the accessibility, crystallinity and capillary structure of cellulose and the branching of hemicelluloses—seem to have little or no effect on cell wall degradation in vivo. In contrast, other antiquality substances (tannins, cutin and silica), plant antomy, environmental factors, factors modulating microbial growth and animal physiology influence cell wall utilisation. Future research in this field should focus on the effects of phenolic structure and of cell wall and tissue organisation on carbohydrate degradation.     

Cloning and characterization of WMSU1, a Williopsis saturnus var. mrakii gene encoding a new yeast SUN protein involved in the cell wall structure

SUN proteins of Saccharomyces cerevisiae have been defined on the basis of high homologies in their C-terminal domain. Recently, two of these four proteins were shown to be involved in cell wall morphogenesis (Mouassite et al., 2000a). In the present study, we have isolated WMSU1 (Accession No. AF418983), a new SUN-related gene, from W. saturnus var. mrakii MUCL 41968. Sequencing of the gene revealed an open reading frame coding for 402 amino acids. The predicted amino acid sequence of WMSU1 is closely related to the S. cerevisiae SUN proteins and to other yeast proteins involved in cell wall metabolism. WMSU1 is proposed to encode a cell wall protein since its predicted product contains a signal sequence, a Kex2p cleavage site and a serine/threonine-rich N-terminal domain. Southern blot analysis of the W. saturnus var. mrakii MUCL 41968 genome using the highly conserved domain of WMSU1 as a probe suggested that the isolated gene belongs to a multigenic family. Expression of WMSU1 in E. coli led to a 45 kDa protein, which appeared to be toxic to this host. Scanning electron microscopy analysis of a recombinant S. cerevisiae producing Wmsu1p showed that this strain exhibited an altered cell wall, thus pointing to a probable role of this protein in the cell wall structure.     

Design of an ohmic reactor to study the kinetics of thermal reactions in liquid products

An ohmic reactor was developed at a laboratory-scale to study the kinetics of thermal reactions in liquid products such as milk and infant formula in the UHT domain. Temperature mapping revealed good thermal homogeneity with a maximum difference of 3 °C in the treatment cell. The ohmic reactor enabled determination of the electrical conductivity of the product under the real thermal conditions with a precision of ±15%. Reproducible thermal profiles were obtained with a 2.3% relative variation for the heating phase, 1% for holding and 20% for cooling. The FAST index, giving a global measurement of the extent of the Maillard reaction in dairy products, was used to estimate the reproducibility of a thermal reaction with an average standard deviation of 3.8%. Finally, a semi-empirical model was developed to predict product temperature history during a complete thermal treatment with good adjustment for heating and holding and acceptable adjustment for cooling.     

Mapping of RFID tag readability in relation to the food content in a refrigerated sea container at 915 MHz

Perishable foods are extremely sensitive to temperature abuse often observed during sea transportation, which regularly involves long transit times. The goal of this study was to compare the effects of the cargo on RFID (radio frequency identification) tag readability to achieve real-time temperature monitoring. A 12 m long refrigerated sea container (68 m³) and a 915 MHz RFID system were used. The container was loaded three times with different food products: canned vegetables, fresh meat and frozen bread. Each load was instrumented with 42 RFID tags evenly distributed throughout the volume. Results showed that canned vegetables provide the best readings (97.6% of tags read), followed by fresh meat (61.9%) and frozen bread (57.1%) respectively. These results validated that radio waves at 915 MHz are absorbed by high water as well as ice contents. However, spacing between metal surfaces and tags can allow excellent RFID readability even if RF reflects on metallic surfaces.

Industrial relevance

The food industry is facing great challenges when it comes to food transportation and distribution. Marine transportation is a slow operation that can expose shipments to a significant range of non-ideal temperatures. Refrigeration units may experience failure during shipment, which inevitably causes losses in quality. The implementation of a real-time temperature monitoring system within a container can provide a good tool to address this issue. Radio frequency technology definitely offers additional benefits such as real-time monitoring as well as tracking and tracing.     

In Vitro Validation of the Therapeutic Potential of Dendrimer-Based Nanoformulations against Tumor Stem Cells

Tumor cells with stem cell properties are considered to play major roles in promoting the development and malignant behavior of aggressive cancers. Therapeutic strategies that efficiently eradicate such tumor stem cells are of highest clinical need. Herein, we performed the validation of the polycationic phosphorus dendrimer-based approach for small interfering RNAs delivery in in vitro stem-like cells as models. As a therapeutic target, we chose Lyn, a member of the Src family kinases as an example of a prominent enzyme class widely discussed as a potent anti-cancer intervention point. Our selection is guided by our discovery that Lyn mRNA expression level in glioma, a class of brain tumors, possesses significant negative clinical predictive value, promoting its potential as a therapeutic target for future molecular-targeted treatments. We then showed that anti-Lyn siRNA, delivered into Lyn-expressing glioma cell model reduces the cell viability, a fact that was not observed in a cell model that lacks Lyn-expression. Furthermore, we have found that the dendrimer itself influences various parameters of the cells such as the expression of surface markers PD-L1, TIM-3 and CD47, targets for immune recognition and other biological processes suggested to be regulating glioblastoma cell invasion. Our findings prove the potential of dendrimer-based platforms for therapeutic applications, which might help to eradicate the population of cancer cells with augmented chemotherapy resistance. Moreover, the results further promote our functional stem cell technology as suitable component in early stage drug development.     

Highly flexible transparent film heaters based on random networks of silver nanowires

We demonstrate a new concept for the fabrication of flexible transparent thin film heaters based on silver nanowires. Thanks to the intrinsic properties of random networks of metallic nanowires, it is possible to combine bendability, transparency and high heating performances at low voltage, typically below 12 V which is of interest for many applications. This is currently not possible with transparent conductive oxide technologies, and it compares well with similar devices fabricated with carbon nanotubes or graphene. We present experiments on glass and poly(ethylene naphthalate) (PEN) substrates (with thicknesses of 125 μm and extremely thin 1.3 μm) with excellent heating performances. We point out that the amount of silver necessary to realize the transparent heaters is very low and we also present preliminary results showing that this material can be efficiently used to fabricate photochromic displays. To our knowledge, this is the first report of metallic nanowire-based transparent thin film heaters. We think these results could be a useful approach for the engineering of highly flexible and transparent heaters which are not attainable by existing processes.      

Second-Generation CD73 Inhibitors Based on a 4,6-Biaryl-2-thiopyridine Scaffold

Various series of 4,6-biaryl-2-thiopyridine derivatives were synthesized and evaluated as potential ecto-5′-nucleotidase (CD73) inhibitors. Two synthetic routes were explored and the coupling of 4,6-disubstituted 3-cyano-2-chloro-pyridines with selected thiols allowed us to explore the structural diversity. Somehow divergent results were obtained in biological assays on CD73 inhibition using either the purified recombinant protein or cell-based assays, highlighting the difficulty to target protein-protein interface on proteins existing as soluble and membrane-bound forms. Among the 18 new derivatives obtained, three derivatives incorporating morpholino substituents on the 4,6-biaryl-2-thiopyridine core were shown to be able to reverse the adenosine-mediated immune suppression on human T cells. The higher blockade efficiency was observed for 2-((3-cyano-4,6-bis(4-morpholinophenyl)pyridin-2-yl)thio)-N-(isoxazol-3-yl)acetamide (with total reversion at 100 μM) and methyl 2-((3-cyano-4,6-bis(4-morpholinophenyl)pyridin-2-yl)thio)acetate (with partial reversion at 10 μM). Thus, this series of compounds illustrates a new chemotype of CD73 allosteric inhibitors.