Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Directed discovery of tetrapeptide emulsifiers

Oil in water emulsions are an important class of soft material that are used in the food, cosmetic, and biomedical industries. These materials are formed through the use of emulsifiers that are able to stabilize oil droplets in water. Historically emulsifiers have been developed from lipids or from large biomolecules such as proteins. However, the ability to use short peptides, which have favorable degradability and toxicity profiles is seen as an attractive alternative. In this work, we demonstrate that it is possible to design emulsifiers from short (tetra) peptides that have tunability (i.e., the surface activity of the emulsion can be tuned according to the peptide primary sequence). This design process is achieved by applying coarse grain molecular dynamics simulation to consecutively reduce the molecular search space from the 83,521 candidates initially considered in the screen to four top ranking candidates that were then studied experimentally. The results of the experimental study correspond well to the predicted results from the computational screening verifying the potential of this screening methodology to be applied to a range of different molecular systems

Novel oral microscope gives mechanistic insights into colloidal drivers of friction in oral biofilms

Texture and mouthfeel are central to the sensory enjoyment of food and beverages. Yet our incomplete understanding of how food boluses are transformed in the mouth limits our texture prediction ability. As well as thin film tribology, the interaction of food colloids with the oral tissue and salivary biofilms plays a key role in texture perception via mechanoreceptors in the papillae. In this study we describe the development of an oral microscope capable of quantitative characterization of the inactions of food colloids with papillae and their concurrent saliva biofilm. We also highlight how the oral microscope revealed key microstructural drivers of several topical phenomena (oral residue formation, coalescence in-mouth, grittiness of protein aggregates and finally microstructural origin of polyphenol astringency) in the domain of texture creation. The coupling of a fluorescent food grade dye with image analysis enabled specific and quantitative determination of the microstructural changes in mouth. Emulsions either underwent no aggregation, small aggregation, or extensive aggregation depending on whether their surface charge facilitated complexation with the saliva biofilm. Quite surprisingly cationic gelatin emulsions that were already aggregated with saliva in mouth underwent coalescence if subsequently exposed to tea polyphenols (EGCG). Large protein aggregates were found to aggregate with the saliva coated papillae, increasing their size tenfold and possibly explaining why there are perceived as gritty. An exciting observation was the oral microstructural changes that occurred upon exposure to tea polyphenols (EGCG). Filiform papillae shrunk, and the saliva biofilm was seen to precipitate/collapse, exposing a very rough tissue surface. These tentative early steps are the first in vivo microstructural insights into the different food oral transformations that are drivers of key texture sensation

Tailoring the digestion of structured emulsions using mixed monoglyceride-caseinate interfaces

The destabilisation of emulsions within the stomach alters their droplet size and surface area, which in turn influences the rate and extent of fat digestion. In this study, we sought to gain further understanding of the mechanisms of the colloidal destabilisation of emulsions during digestion by examining how the composition of the interface impacts on these destabilisation processes. Understanding of emulsion destabilisation within the stomach was then linked to the extent of fat digestion through in vitro lipolysis measurements and in vivo triglyceride absorption studies. Two factors were examined; 1) co-variance of protein and monoglyceride composition at the droplet surface and 2) fat phase composition. Of the two emulsifiers present, caseinate provided the colloidal stability to the emulsion via a combination of electrostatic and steric repulsion. The acidic pH of gastric fluid resulted in a loss of electrostatic charge and a collapse of the casein steric layer, ultimately causing the emulsion to flocculate. The presence of monoglyceride influenced the emulsions susceptibility to flocculation in gastric juice and the resistance of the interface to film rupture which impacted the degree of droplet coalescence. It appeared that there was an optimum ratio between monoglyceride and protein at the interface for emulsion destabilisation. An excessive decrease in protein at the interface as monoglyceride concentration increased limited initial droplet flocculation, because there were fewer junction points for protein bridging between droplets. These changes to emulsion droplet structure had an impact on the in vitro rate and the extent of lipolysis. However triglyceride absorption in vivo was only significantly impacted when the coalesced droplet structure (e.g. emulsion containing solid fat) was maintained until the intestine.

Consumer perceptions of plant based beverages: The Ghanaian consumer's perspective

This study identified factors influencing consumer desirability for a concept beverage from tiger nut milk and cocoa pulp using qualitative focus groups with four demographic groups: mothers, young adults, adults, and middle-aged adults. Specifically, Ghanaian consumers’ knowledge of plant-based beverages (PBB), sensory attributes driving preferences and selection, and willingness to purchase were investigated. Focus group discussions were thematically analyzed by Attride-Stirling's method using ATLAS.ti.7 software. Most consumers were knowledgeable of PBB. Health and nutrition were main drivers of consumption while taste, cost, availability, and culture were barriers to consumption. Drivers of consumer preference of PBB differed across demographic groups. Environmentally conscious consumers (mothers, adults, and middle-aged) preferred paper packaging while young adults preferred plastic packaging for convenience. Middle-aged adults preferred unsweetened versions for health reasons and mothers preferred unflavoured PBB for their children. Consumers expressed willingness to purchase the concept beverage, citing innovation, taste, and health benefits as main drivers. Industrial Relevance: Increased consumer awareness of the relationship between diet and disease and the importance of consuming healthful foods has informed a switch to more plant-based diets. Our results provide valuable insights to facilitate the development of an acceptable plant-based beverage for Ghanaian consumers

Impact of different biopolymer networks on the digestion of gastric structured emulsions

The deliberate design of food structures that impact on lipid digestion has received increasing attention because of the need for solutions to combat nutrition related concerns such as obesity and metabolic syndrome. In this study we examined how the hierarchical structure of foods can impact lipid digestion by incorporating gastric structuring emulsions in different biopolymer networks, namely i) a thermally reversible gelatine network, ii) a colloidal casein network, and iii) a concentrated starch particulate dispersion. The digestive breakdown of these emulsion filled biopolymer gels was followed by fat digestion kinetics in vitro and human clinical study (in vivo), rheological measurements and confocal laser scanning microscopy. The parent caseinate/monoglyceride (CasMag) stabilised emulsion underwent extensive partial coalescence upon exposure to gastric juice and as a result had very slow lipolysis (in vitro and in vivo). When the emulsion was incorporated within the biopolymer networks the rates of lipolysis were strongly correlated with the extent of partial coalescence of the CasMag emulsion, which was directly influenced by the structure and breakdown properties of each different biopolymer network. The way that biopolymer networks alter the digestion of the parent CasMag emulsion is likely affected by; i) how well the digestive juices mixed with the network/emulsion and, ii) the frequency and speed of droplet encounters, both of which have a direct impact on the ability of emulsions to undergo flocculation and (partial) coalescence. This knowledge may have important implications for the design and testing of real foods to understand and control the digestive behaviour of food nutrients.

Colloidal dynamics of emulsion droplets in mouth

The interaction of emulsions with the tongue is key to the sensory appeal of food and can potentially be exploited for oral/buccal pharmaceutical delivery. Whilst there is good understanding of the different mucoadhesive forces governing emulsion interaction with the tongue, their relative importance is not well understood. In addition, the physical location of emulsions within the saliva papillae on the tongue is not understood at all. A combination of ex vivo salivary film, and in vivo oral coating experiments were used to determine the importance of different mucoadhesive forces. Mucoadhesion of cationic emulsions was largely driven by electrostatic complexation. SDS-PAGE of the in vivo saliva coating highlighted that mucins were largely responsible for cationic emulsion mucoadhesion. Anionic emulsions were bound via hydrophobic/steric interactions to small salivary proteins typically located away from the mucin anchor points. The physical location and clustering of emulsions relative to the salivary film/papillae was probed via the invention of a fluorescent oral microscope. Cationic emulsions were densely clustered close to the papillae whilst anionic emulsions were suspended in the salivary film above the papillae. Interestingly, non-ionic emulsions were also trapped within the salivary film above the papillae as individual droplets. These findings highlight that whilst electrostatic complexation with saliva is a powerful mucoadhesive force, hydrophobic and steric interactions also act to induce oral retention of emulsions. The differences in physical location and clustering of emulsions within the salivary film hint at the 3D locations of the different salivary proteins driving each mucoadhesive interaction. This novel understanding of emulsion saliva/papillae interactions has potential to aid efficacy of buccal pharmaceutical delivery and the reduction of astringency in plant-based foods