Prebiotic Potential of a Maize-Based Soluble Fibre and Impact of Dose on the Human Gut Microbiota

Dietary management of the human gut microbiota towards a more beneficial composition is one approach that may improve host health. To date, a large number of human intervention studies have demonstrated that dietary consumption of certain food products can result in significant changes in the composition of the gut microbiota i.e. the prebiotic concept. Thus the prebiotic effect is now established as a dietary approach to increase beneficial gut bacteria and it has been associated with modulation of health biomarkers and modulation of the immune system. Promitor™ Soluble Corn Fibre (SCF) is a well-known maize-derived source of dietary fibre with potential selective fermentation properties. Our aim was to determine the optimum prebiotic dose of tolerance, desired changes to microbiota and fermentation of SCF in healthy adult subjects. A double-blind, randomised, parallel study was completed where volunteers (n = 8/treatment group) consumed 8, 14 or 21 g from SCF (6, 12 and 18 g/fibre delivered respectively) over 14-d. Over the range of doses studied, SCF was well tolerated Numbers of bifidobacteria were significantly higher for the 6 g/fibre/day compared to 12g and 18g/fibre delivered/day (mean 9.25 and 9.73 Log10 cells/g fresh faeces in the pre-treatment and treatment periods respectively). Such a numerical change of 0.5 Log10 bifidobacteria/g fresh faeces is consistent with those changes observed for inulin-type fructans, which are recognised prebiotics. A possible prebiotic effect of SCF was therefore demonstrated by its stimulation of bifidobacteria numbers in the overall gut microbiota during a short-term intervention.     

Impacts of dynamic degradation on the morphological and mechanical characterisation of porous magnesium scaffold

Biomechanics and Modeling in Mechanobiology - This study employs a computational approach to analyse the impact of morphological changes on the structural properties of biodegradable porous Mg...     

Pyrosequencing protocol using a universal biotinylated primer for mutation detection and SNP genotyping

DNA sequencing has markedly changed the nature of biomedical research, identifying millions of polymorphisms along the human genome that now require further analysis to study the genetic basis of human diseases. Among the DNA-sequencing platforms available, Pyrosequencing has become a useful tool for medium-throughput single nucleotide polymorphism (SNP) genotyping, mutation detection, copy-number studies and DNA methylation analysis. Its 96-well genotyping format allows reliable results to be obtained at reasonable costs in a few minutes. However, a specific biotinylated primer is usually required for each SNP under study to allow the capture of single-stranded DNA template for the Pyrosequencing assay. Here, we present an alternative to the standard labeling of PCR products for analysis by Pyrosequencing that circumvents the requirement of specific biotinylated primers for each SNP of interest. This protocol uses a single biotinylated primer that is simultaneously incorporated into all M13-tagged PCR products during the amplification reaction. The protocol covers all steps from the PCR amplification and capture of single-stranded template, its preparation, and the Pyrosequencing assay itself. Once the correct primer stoichiometry has been determined, the assay takes around 2 h for PCR amplification, followed by 15-20 min (per plate) to obtain the genotypes.     

Bundle sheath extensions affect leaf structural and physiological plasticity in response to irradiance

Coordination between structural and physiological traits is key to plants' responses to environmental fluctuations. In heterobaric leaves, bundle sheath extensions (BSEs) increase photosynthetic performance (light‐saturated rates of photosynthesis, A_max) and water transport capacity (leaf hydraulic conductance, K_leaf). However, it is not clear how BSEs affect these and other leaf developmental and physiological parameters in response to environmental conditions. The obscuravenosa (obv) mutation, found in many commercial tomato varieties, leads to absence of BSEs. We examined structural and physiological traits of tomato heterobaric and homobaric (obv) near‐isogenic lines grown at two different irradiance levels. K_leaf, minor vein density, and stomatal pore area index decreased with shading in heterobaric but not in homobaric leaves, which show similarly lower values in both conditions. Homobaric plants, on the other hand, showed increased A_max, leaf intercellular air spaces, and mesophyll surface area exposed to intercellular airspace (S_mes) in comparison with heterobaric plants when both were grown in the shade. BSEs further affected carbon isotope discrimination, a proxy for long‐term water‐use efficiency. BSEs confer plasticity in traits related to leaf structure and function in response to irradiance levels and might act as a hub integrating leaf structure, photosynthetic function, and water supply and demand.     

Feeding habits of the fishes Lutjanus peru and Lutjanus guttatus (Pisces: Lutjanidae) of Guerrero, México

Diet composition of the Pacific snapper (Lutjanus peru) 130-684 mm fork length (FL) and the spotted snapper (Lugjanus guttatus) 120-550 mm FL, was analyzed. Monthly samples were obtained from commercial landings in three regions off the coast of Guerrero, Mexico. Percentage by number (%N), percentage by weight (%W), and percentage of occurrence (%O) were calculated for each prey and summarized as the index of relative importance. Both species are polyphagous predators feeding on a variety of prey: Sixty-eight prey items, mainly fish (%W = 50.9), crustaceans (%W = 35.6), and mollusks (%W = 7.2), were found in the stomach contents of L. peru, while 88 components were identified in the diet of L. guttatus, the most important prey being fish (%W = 50.8) and crustaceans (%W = 43.4). Diet overlap between species is not significant (p<0.05), indicating that competition for food is unlikely. Based on published values of the relative importance index, the diets of these Lutjanidae were analyzed considering different regions of the Pacific coast of Mexico and Costa Rica, and similarities among sites and species were discussed. The cluster analysis showed that similarities among species inhabiting in the same area are more important than within organisms of the same species living in different zones. Results suggest that prey availability rather than food selectivity, conditions the feeding behavior of these fish species.     

The thrombin epitope recognizing thrombomodulin is a highly cooperative hot spot in exosite I

The functional epitope of thrombin recognizing thrombomodulin was mapped using Ala-scanning mutagenesis of 54 residues located around the active site, the Na(+) binding loop, the 186-loop, the autolysis loop, exosite I, and exosite II. The epitope for thrombomodulin binding is shaped as a hot spot in exosite I, centered around the buried ion quartet formed by Arg(67), Lys(70), Glu(77), and Glu(80), and capped by the hydrophobic residues Tyr(76) and Ile(82). The hot spot is a much smaller subset of the structural epitope for thrombomodulin binding recently documented by x-ray crystallography. Interestingly, the contribution of each residue of the epitope to the binding free energy shows no correlation with the change in its accessible surface area upon formation of the thrombin-thrombomodulin complex. Furthermore, residues of the epitope are strongly coupled in the recognition of thrombomodulin, as seen for the interaction of human growth hormone and insulin with their receptors. Finally, the Ala substitution of two negatively charged residues in exosite II, Asp(100) and Asp(178), is found unexpectedly to significantly increase thrombomodulin binding.     

Conflict and post-conflict behavior in a small group of chimpanzees

Chimpanzee research plays a central role in the discussions of conflict negotiation. Reconciliation, or the attraction and affiliation of former opponents following conflict, has been proposed as a central element of conflict negotiation in chimpanzees and various other taxa. In an attempt to expand the database of chimpanzee conflict resolution, conflict and post-conflict behavior were recorded for a small group of socially housed chimpanzees at the Chimpanzee and Human Communication Institute, at Central Washington University. Data were collected over six 6-week periods between 1997 and 2000, for a total of 840 hours of observation, resulting in a substantial post-conflict (PC) and matched control (MC) data set. The data demonstrate this group’s tendencies to maintain visual contact and closer proximity after conflicts. Dyadic corrected conciliatory tendencies ranged between 0 – 37.5% and averaged 17.25% across all dyads. Individual corrected conciliatory tendencies ranged between 5.8 and 32%. The results of this study combined with recent publications on captive and free-ranging chimpanzee post-conflict behavior suggest that variation in post-conflict behavior may be important to our understanding of chimpanzee conflict negotiation, and may also have implications for the design and management of captive chimpanzee enclosures and social groups, respectively.