Multimodal Control of Liquid Crystalline Mesophases from Surfactants with Photoswitchable Tails

Non-invasive manipulation of the hierarchical structure of functional materials is a key challenge in the advancement of optoelectronics, energy conversion and storage devices and drug delivery systems. Here, using a combination of small-angle X-ray scattering and polarised optical microscopy, we decipher the various structure/self- assembly relationships of neutral surfactants bearing photoswitchable tails, which self-organise into a rich variety of lyotropic liquid crystalline mesophases. Facile, multimodal control of the nanoscale morphology of these single-component systems is achieved through: i) molecular structure, via careful selection of the alkyl tail/ethylene oxide headgroup lengths; ii) concentration; iii) temperature; and iv) photoisomerisation. The nanoscale architectures range from the weakly concentrated hyperswollen lamellar phases, the more common lyotropic lamellar and hexagonal phases, to pure thermotropic liquid crystals; all of which are accessible at room temperature. Photoisomerisation with UV light leads to the reversible destruction of the liquid crystalline phase, which can be spatially controlled through the use of a mask. This extensive study demonstrates the versatility of neutral photosurfactants and paves the way for them to be investigated for new applications, such as photoresponsive templates or drug delivery systems.Isaac Newton Trust/University of Cambridge Early Career Support Scheme grant. Irish Research Council EU COST action MP120

Light-responsive self-assembly of a cationic azobenzene surfactant at high concentration.

The formation of high-concentration mesophases by a cationic azobenzene photosurfactant is described for the first time. Using a combination of polarised optical microscopy and small-angle X-ray scattering, optically anisotropic, self-assembled structures with long-range order are reported. The mesophases are disrupted or lost upon UV irradiation

Possible role of available phosphorus in potentiating the use of low-protein diets for broiler chicken production

A total of 945 male Ross 308 broiler chicks were used in a growth study to explore the interaction between dietary crude protein concentration and available phosphorus. Nine experimental treatments were constructed factorially by offering low, medium, or standard protein concentrations without or with low, standard, or high available phosphorus. Diets were based on corn, wheat, and soybean meal and all nutrients other than protein/amino acids and available phosphorus were maintained at or above breeder guidelines. Additional synthetic amino acids were used in the diets with low protein concentration in attempt to maintain digestible amino acid supply. Diets were offered to 7 replicate pens of 15 chicks per pen from day 8 to 35. Growth performance was measured during the grower (day 8–24) and finisher (day 25–35) periods. On day 35 carcass composition was determined, blood was drawn for various biochemical measurements and the tibia was excised for mechanical and compositional analyses. Birds that received the low-protein diet had lower terminal body weight and higher feed conversion ratio compared with those that received diets with adequate crude protein content. However, addition of available phosphorus to the low-protein diet resulted in significant reductions in weight-corrected feed conversion that were not evident in the diet with adequate protein content. Bone architecture was only moderately influenced by dietary treatment but birds that ingested the diets containing low and medium protein concentrations had relatively heavier abdominal fat pad weight. Blood biochemistry, especially ammonia, uric acid, and phosphorus, was influenced by both dietary protein and available phosphorus and trends suggested that both axes are involved in protein accretion and catabolism. It can be concluded that performance losses associated with feeding low protein diets to broiler chickens may be partially restored by additional available phosphorus. The implications for use of exogenous enzymes such as protease and phytase and protein nutrition per se warrants further examination

The Efficacy of Avizyme 1500 for Improving Performance of Laying Hens

Suatu percobaan telah dilakukan untuk menguji manfaat penambahan enzim-Avizyme 1500® (Danisco Animal Nutrition, Marlborough, UK) terhadap performan ayam petelur selama periode satu tahun produksi. Ransum kontrol disusun dengan bahan utama terdiri dari jagung dan bungkil kedelai untuk memenuhi kebutuhan gizi ayam petelur strain ISA Brown. Dua perlakuan yang diuji adalah ransum kontrol (C) dan ransum yang diberi enzim (C + 1000 g Avizyme/ton ransum. Setiap jenis ransum diberikan pada 80 ekor ayam petelur (20 ulangan dan 4 ekor/ulangan) mulai umur 20 hingga 72 minggu. Selama percobaan tersebut dilakukan pengamatan terhadap performan ayam petelur (konsumsi pakan, produksi telur, bobot telur, total berat produksi telur atau egg mass, konfersi pakan atau FCR, mortalitas, perubahan bobot badan dan kualitas telur). Perbedaan perlakuan dianalisis dengan menggunakan t-test. Hasil penelitian menunjukkan bahwa penambahan Avizyme 1500 kedalam pakan dapat menurunkan konsumsi pakan 4% (P < 0,01), mengurangi mortalitas dari 15% menjadi 3,75% (P < 0.01) serta memperbaiki efisiensi penggunaan pakan (FCR) sebanyak 3% (P < 0,05). Mortalitas yang tinggi pada ayam kontrol (15%) terjadi karena adanya infeksi E.coli, sesuai uji post-mortem yang dilakukan. Akan tetapi, produksi telur (HD and HH), bobot telur dan massa telur tidak nyata dipengaruhi oleh penambahan Avizyme didalam pakan. Kualitas telur (HU, indeks kuning telur, bobot kuning telur dan tebal kerabang tidak nyata dipengaruhi oleh penambahan Avizyme dalam ransum. Oleh karena itu disimpulkan bahwa penambahan 1000 g Avizyme /ton ransum dapat memperbaiki efisiensi penggunaan pakan (FCR) sebagai akibat penurunan konsumsi pakan, tanpa merubah produktifitasnya. A trial was conducted in order to study the effect of the supplementation of Avizyme 1500® (Danisco Animal Nutrition, Marlborough, UK) on the performance of laying hens for one year. A control diet based on corn -soybean meal was formulated to meet nutrient requirement of ISA Brown laying hens. Two treatments, the control diet (C) and C + 1000 g Avizyme/tonne diet were tested. Each diet was fed to 80 birds (20 replicates of 4 birds) from 20 to 72 weeks of age, and performances of birds (feed intake, egg production, egg size, egg mass, feed conversion ratio, and egg quality) were measured. All data were subject to analyses of variance following the t-test. Results showed that the addition of Avizyme 1500 to the feed reduced feed intake by 4% (P < 0.01), mortality by 75 % or from 15% to 3.75% (P < 0.01) and improved the feed conversion ratio by 3 % (P < 0.05). The high mortality of the control treatment (15%) is explained by an E.coli infection that was observed following the postmortem examination of dead birds. The egg production (HD and HH), egg size and egg mass however were not significantly affected by the Avizyme supplementation. Egg quality (HU, yolk colour score, yolk weight and shell thickness) was not significantly affected by Avizyme supplementation. It can be concluded that the supplementation of 1000 g Avizyme /tonne of diet improved feed efficiency and this was mediated via a reduction in feed intake

A single-component photorheological fluid with light-responsive viscosity.

Viscoelastic fluids whose rheological properties are tunable with light have the potential to deliver significant impact in fields relying on a change in flow behavior, such as in-use tuning of combined efficient heat-transfer and drag-reduction agents, microfluidic flow and controlled encapsulation and release. However, simple, single-component systems must be developed to allow integration with these applications. Here, we report a single-component viscoelastic fluid, capable of a dramatic light-sensitive rheological response, from a neutral azobenzene photosurfactant, 4-hexyl-4'butyloxymonotetraethylene glycol (C6AzoOC4E4) in water. From cryo-transmission electron microscopy (TEM), small-angle X-ray scattering (SAXS) and rheology measurements, we observe that the photosurfactant forms an entangled network of wormlike micelles in water, with a high viscosity (28 Pa s) and viscoelastic behaviour. UV irradiation of the surfactant solution creates a less dense micellar network, with some vesicle formation. As a result, the solution viscosity is reduced by four orders of magnitude (to 1.2 × 10-3 Pa s). This process is reversible and the high and low viscosity states can be cycled several times, through alternating UV and blue light irradiation

A mono-component microbial protease improves performance, net energy, and digestibility of amino acids and starch, and upregulates jejunal expression of genes responsible for peptide transport in broilers fed corn/wheat-based diets supplemented with xylanase and phytase

A total of 90 male Ross 308 broiler chicks were used in a digestibility and performance bioassay to explore the effect of reduction in dietary protein and digestible amino acids and inclusion of an exogenous mono-component protease on amino acid digestibility, net energy, jejunal gene expression, and bird performance. Four dietary treatments were created by the supplementation, or not, of 2 control diets with a mono-component exogenous protease. The control diets were corn/wheat/soybean meal-based and were formulated to be either nutritionally adequate or reduced in protein and amino acids (around 3%). The 2 control diets were supplemented with xylanase and phytase (2000 FYT). Treatments were therefore arranged as a 2 × 2 factorial design. The reduction in diet nutrient density had no significant effect on various experimental outcomes (including bird performance, amino acid digestibility, and net energy [NE]) that were measured with the exception of a reduction in the expression of aminopeptidase N and glucose transporter 2. However, the addition of exogenous protease resulted in an increase in weight gain and a reduction in feed conversion ratio (around 4%; PPP= 0.06). Protease addition also resulted in an increase in both apparent metabolizable energy (AME) (+73 kcal/kg; PPP= 0.06). These results confirm the efficacy of exogenous protease in broiler diets that contain both xylanase and phytase and suggest substantial beneficial effects that extend beyond protein and amino acid nutrition. The effect of exogenous protease on energy partitioning, starch digestibility and the efficiency of nitrogen cycling is an area for further study

Plasmodium falciparum heterochromatin protein 1 binds to tri-methylated histone 3 lysine 9 and is linked to mutually exclusive expression of var genes

Increasing experimental evidence shows a prominent role of histone modifications in the coordinated control of gene expression in the human malaria parasite Plasmodium falciparum. The search for the histone-mark-reading machinery that translates histone modifications into biological processes, such as formation of heterochromatin and antigenic variation is of foremost importance. In this work, we identified the first member of a histone modification specific recognition protein, an orthologue of heterochromatin protein 1 (PfHP1). Analysis of the PfHP1 amino-acid sequence revealed the presence of the two characteristic HP1 domains: a chromodomain (CD) and a chromo shadow domain (CSD). Recombinant CD binds to di- and tri-methylated lysine 9 from histone H3, but not to unmodified or methylated histone H3 in lysine 4. PfHP1 is able to interact with itself to form dimers, underlying its potential role in aggregating nucleosomes to form heterochromatin. Antibodies raised against PfHP1 detect this molecule in foci at the perinuclear region. ChIP analysis using anti-PfHP1 shows that this protein is linked to heterochromatin of subtelomeric non-coding repeat regions and monoallelic expression of the major virulence var gene family. This is the first report implicating an HP1 protein in the control of antigenic variation of a protozoan parasite

Functional conservation of the Drosophila hybrid incompatibility gene Lhr

<p>Abstract</p> <p>Background</p> <p>Hybrid incompatibilities such as sterility and lethality are commonly modeled as being caused by interactions between two genes, each of which has diverged separately in one of the hybridizing lineages. The gene <it>Lethal hybrid rescue </it>(<it>Lhr</it>) encodes a rapidly evolving heterochromatin protein that causes lethality of hybrid males in crosses between <it>Drosophila melanogaster </it>females and <it>D. simulans </it>males. Previous genetic analyses showed that hybrid lethality is caused by <it>D. simulans Lhr </it>but not by <it>D. melanogaster Lhr</it>, confirming a critical prediction of asymmetry in the evolution of a hybrid incompatibility gene.</p> <p>Results</p> <p>Here we have examined the functional properties of <it>Lhr </it>orthologs from multiple Drosophila species, including interactions with other heterochromatin proteins, localization to heterochromatin, and ability to complement hybrid rescue in <it>D. melanogaster</it>/<it>D. simulans </it>hybrids. We find that these properties are conserved among most <it>Lhr </it>orthologs, including <it>Lhr </it>from <it>D. melanogaster</it>, <it>D. simulans </it>and the outgroup species <it>D. yakuba</it>.</p> <p>Conclusions</p> <p>We conclude that evolution of the hybrid lethality properties of <it>Lhr </it>between <it>D. melanogaster </it>and <it>D. simulans </it>did not involve extensive loss or gain of functions associated with protein interactions or localization to heterochromatin.</p

Unique Properties of Eukaryote-Type Actin and Profilin Horizontally Transferred to Cyanobacteria

A eukaryote-type actin and its binding protein profilin encoded on a genomic island in the cyanobacterium Microcystis aeruginosa PCC 7806 co-localize to form a hollow, spherical enclosure occupying a considerable intracellular space as shown by in vivo fluorescence microscopy. Biochemical and biophysical characterization reveals key differences between these proteins and their eukaryotic homologs. Small-angle X-ray scattering shows that the actin assembles into elongated, filamentous polymers which can be visualized microscopically with fluorescent phalloidin. Whereas rabbit actin forms thin cylindrical filaments about 100 µm in length, cyanobacterial actin polymers resemble a ribbon, arrest polymerization at 5-10 µm and tend to form irregular multi-strand assemblies. While eukaryotic profilin is a specific actin monomer binding protein, cyanobacterial profilin shows the unprecedented property of decorating actin filaments. Electron micrographs show that cyanobacterial profilin stimulates actin filament bundling and stabilizes their lateral alignment into heteropolymeric sheets from which the observed hollow enclosure may be formed. We hypothesize that adaptation to the confined space of a bacterial cell devoid of binding proteins usually regulating actin polymerization in eukaryotes has driven the co-evolution of cyanobacterial actin and profilin, giving rise to an intracellular entity