Impact of Different Fecal Processing Methods on Assessments of Bacterial Diversity in the Human Intestine.

The intestinal microbiota are integral to understanding the relationships between nutrition and health. Therefore, fecal sampling and processing protocols for metagenomic surveys should be sufficiently robust, accurate, and reliable to identify the microorganisms present. We investigated the use of different fecal preparation methods on the bacterial community structures identified in human stools. Complete stools were collected from six healthy individuals and processed according to the following methods: (i) randomly sampled fresh stool, (ii) fresh stool homogenized in a blender for 2 min, (iii) randomly sampled frozen stool, and (iv) frozen stool homogenized in a blender for 2 min, or (v) homogenized in a pneumatic mixer for either 10, 20, or 30 min. High-throughput DNA sequencing of the 16S rRNA V4 regions of bacterial community DNA extracted from the stools showed that the fecal microbiota remained distinct between individuals, independent of processing method. Moreover, the different stool preparation approaches did not alter intra-individual bacterial diversity. Distinctions were found at the level of individual taxa, however. Stools that were frozen and then homogenized tended to have higher proportions of Faecalibacterium, Streptococcus, and Bifidobacterium and decreased quantities of Oscillospira, Bacteroides, and Parabacteroides compared to stools that were collected in small quantities and not mixed prior to DNA extraction. These findings indicate that certain taxa are at particular risk for under or over sampling due to protocol differences. Importantly, homogenization by any method significantly reduced the intra-individual variation in bacteria detected per stool. Our results confirm the robustness of fecal homogenization for microbial analyses and underscore the value of collecting and mixing large stool sample quantities in human nutrition intervention studies

Improved Knowledge and Adoption of Recommended Food Safety Practices by Food Recovery Agency Personnel and Volunteers Participating in the Serving Food Safely Program

The tri-state study reported here tested the effectiveness of a curriculum developed and presented in workshops by Extension and research faculty to increase knowledge and promote safe food handling practices of staff and volunteers of food recovery agencies providing rescued and surplus food to vulnerable populations. Results indicated that knowledge and adoption of recommended food safety practices increased for both staff and volunteers following participation in the workshops. The improvement in food safety knowledge and adoption of recommended food safety practices support the continued use of the food safety curriculum in the three states and possibly other areas in the United States

Sodium Propionate or Sodium Butyrate Promotes Fatty Acid Oxidation in HepG2 Cells Under Oxidative Stress

The beneficial effects of sodium butyrate (NaB) and sodium propionate (NaP) on fatty acid oxidation (FAO) genes and production of proinflammatory cytokines related to nonalcoholic fatty liver disease (NAFLD) were evaluated using HepG2 human liver hepatocellular carcinoma cells exposed to palmitate/oleate or lipopolysaccharides (LPSs) as a model. The results showed that NaP or NaB was able to promote FAO, regulate lipolysis, and reduce reactive oxygen species production by significantly increasing the mRNA expression of peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1α), peroxisome proliferator-activated receptor alpha (PPARα), adipose triglyceride lipase (ATGL), carnitine palmitoyltransferase 1 alpha (CPT1α), fibroblast growth factor 21 (FGF21), and uncoupling protein 2 (UCP2) in HepG2 cells. Together, NaP and NaB may produce greater effects by increasing CPT1α, PPARα, and UCP2 mRNA expression in LPS-treated HepG2 cells and by increasing CPT1α and ATGL mRNA expression in palmitate-/oleate-treated HepG2 cells. Only NaP treatment significantly increased FGF21 mRNA expression in palmitate-/oleate-treated HepG2 cells. The enzyme-linked immunosorbent assay results revealed that only pretreatment with LPSs and not palmitate/oleate significantly increased tumor necrosis factor alpha (TNF-α) expression in HepG2 cells. NaP alone or in combination with NaB significantly decreased TNF-α expression in LPS-induced HepG2 cells. The expression of interleukin-8 in both models showed no significant differences in all treatments. NaP and NaB show potential for in vivo studies on NAFLD

Spatial population expansion promotes the evolution of cooperation in an experimental Prisoner's Dilemma

Cooperation is ubiquitous in nature, but explaining its existence remains a central interdisciplinary challenge. Cooperation is most difficult to explain in the Prisoner's Dilemma game, where cooperators always lose in direct competition with defectors despite increasing mean fitness. Here we demonstrate how spatial population expansion, a widespread natural phenomenon, promotes the evolution of cooperation. We engineer an experimental Prisoner's Dilemma game in the budding yeast Saccharomyces cerevisiae to show that, despite losing to defectors in nonexpanding conditions, cooperators increase in frequency in spatially expanding populations. Fluorescently labeled colonies show genetic demixing of cooperators and defectors, followed by increase in cooperator frequency as cooperator sectors overtake neighboring defector sectors. Together with lattice-based spatial simulations, our results suggest that spatial population expansion drives the evolution of cooperation by (1) increasing positive genetic assortment at population frontiers and (2) selecting for phenotypes maximizing local deme productivity. Spatial expansion thus creates a selective force whereby cooperator-enriched demes overtake neighboring defector-enriched demes in a "survival of the fastest". We conclude that colony growth alone can promote cooperation and prevent defection in microbes. Our results extend to other species with spatially restricted dispersal undergoing range expansion, including pathogens, invasive species, and humans

Adoption of Plantain within New Zealand Farming Systems

In New Zealand, plantain has been incorporated into the pasture forage base in three ways: as a short-term pure crop; as a major component in “herb mixes” that include clovers and chicory; and as a minor component in perennial grass-based swards. All types are typically grazed in-situ. Given the incentive to optimise the plantain proportion in livestock diet to mitigate nitrogen losses and the observed lack of persistence in grass-dominant pasture over time, there is a need to use various pasture types strategically across a farm system to ensure a long-term sustainable contribution of plantain to feed intake. The inclusion of plantain in the forage base should be relatively straightforward since farmers are already familiar with establishing and managing forage crops and mixed-species pastures. However, there are still technical questions to answer and incentives to implement before we can achieve the region-wide adoption necessary to result in a measurable impact on water quality. The Tararua District, on the east coast of the North Island of New Zealand, represents a useful case study of adoption in a strong dairy farming region. Some underpinning elements for successful adoption were in place: 1) national agronomic experience in using a plantain cultivar released in 1996; and 2) regulatory push in terms of reducing N leaching losses on farms. However, other initiatives were required to see meaningful progress: provision of data from local dairy farm systems, focused on the impact on forage supply/quality; a targeted extension program by a trusted sector leader agency (DairyNZ); individual farmer risk-taking and leadership in establishing and managing new crops and pastures. After three years, awareness is well embedded in the rural community and approximately 30% of dairy farms within the district have started to use plantain

Substrate oxidation and energy expenditure in athletes and nonathletes consuming isoenergetic high- and low-fat diets

Changes in substrate oxidation with isoenergetic high-carbohydrate (HC) and high-fat (HF) diets in male nonathletic subjects, aerobically trained athletes, and weight-trained athletes were examined in a crossover study. A whole-room respiration chamber was used to measure 24-h energy expenditure (EE) and substrate oxidation with control, He, or HF diets for 7 d. The nonathletic group had higher 24-h EE (P \u3c 0.05), exercise EE (P \u3c 0.03), and resting metabolic rate (P \u3c 0.04) than did the aerobically trained athletes when these measurements were corrected for lean body mass. Fat oxidation was significantly correlated with lean body mass and diet. However, athletic status had no effect on substrate oxidation. Carbohydrate oxidation across groups increased acutely by 23% after 24 h of the HC diet (P \u3c 0.0001). Carbohydrate balance increased significantly over time with the HC diet (P \u3c 0.002) and decreased acutely after return to the control diet (P \u3c 0.0001). With the HF diet, carbohydrate balance increased and was significantly different from balance with the control diet by day 7 (P \u3c 0.03). Fat balance decreased significantly with both the HF (P \u3c 0.04) and HC (P = 0.0075) diets by day 7. Carbohydrate oxidation correlated with carbohydrate intake with both the control (r = 0.61, P \u3c 0.01) and HC diets (r = 0.59, P \u3c 0.02), but not the HF diet. Fat oxidation was not correlated with fat intake. In conclusion, substrate oxidation in a respiration chamber is significantly affected by diet, but not by prior athletic training

Peptide YY and proglucagon mRNA expression patterns and regulation in the gut

Objective: Peptide YY (PYY) and glucagon-like peptide-1 are important in the control of energy homeostasis and are both secreted from the gut in response to ingested nutrients. However, more studies are needed on nutrient regulation of their gene expression patterns in specific areas of the gut. This study detailed PYY and proglucagon (the gene that encodes glucagon-like peptide-1) gene expression patterns and regulation in the gut. We further examined the regulation of PYY and proglucagon mRNA by a diet containing fermentation- resistant starch (in vivo) and butyrate (in vitro). Research Methods and Procedures: Quantitative real time reverse transcriptase-polymerase chain reaction was used to measure PYY and proglucagon gene expression in epithelial cells collected from the duodenum, jejunum, cecum, and colon in normal Sprague-Dawley rats and in rats fed a resistant starch diet for 4 weeks. The same measurements were also performed in primary epithelial cells collected from the cecum and colon of normal rats after the cells were incubated with butyrate for 3 hours. Results: The gene expression patterns for PYY and proglucagon are similar to their peptide distribution patterns in the gut. Also, PYY and proglucagon mRNA expression were up-regulated in the cecum and colon in resistant-starch-fed rats. Butyrate increased PYY and proglucagon gene expression in a dose-dependent manner in vitro. Discussion: Our data provide evidence that the distal part of the gut has the ability to sense nutrients such as butyrate, resulting in the up-regulation of PYY and proglucagon gene expression. Copyright © 2006 NAASO

Failure to ferment dietary resistant starch in specific mouse models of obesity results in no body fat loss

Resistant starch (RS) is a fermentable fiber that decreases dietary energy density and results in fermentation in the lower gut. The current studies examined the effect of RS on body fat loss in mice. In a 12 week study (study 1), the effect of two different types of RS on body fat was compared with two control diets (0% RS) in C57Bl/6J mice: regular control diet or the control diet that had energy density equal to that of the RS diet (EC). All testing diets had 7% (w/w) dietary fat. In a 16 week study (study 2), the effect of RS on body fat was compared with EC in C57BL/6J mice and two obese mouse models (NONcNZO 10/LtJ or Non/ShiLtJ). All mice were fed control (0% RS) or 30% RS diet for 6 weeks with 7% dietary fat. On the seventh week, the dietary fat was increased to 11% for half of the mice and remained the same for the rest. Body weight, body fat, energy intake, energy expenditure, and oral glucose tolerance were measured during the study. At the end of the studies, the pH of cecal contents was measured as an indicator of RS fermentation. Compared with EC, dietary RS decreased body fat and improved glucose tolerance in C57BL/6J mice but not in obese mice. For other metabolic characteristics measured, the alterations by RS diet were similar for all three types of mice. The difference in dietary fat did not interfere with these results. The pH of cecal contents in RS fed mice was decreased for C57BL/6J mice but not for obese mice, implying the impaired RS fermentation in obese mice. Conclusions: (1) decreased body fat by RS is not simply due to dietary energy dilution in C57Bl/6J mice, and (2) along with their inability to ferment RS, RS fed obese mice did not lose body fat. Thus, colonic fermentation of RS might play an important role in the effect of RS on fat loss. © 2009 American Chemical Society

The AU Microscopii Debris Disk: Multiwavelength Imaging and Modeling

(abridged) Debris disks around main sequence stars are produced by the erosion and evaporation of unseen parent bodies. AU Microscopii (GJ 803) is a compelling object to study in the context of disk evolution across different spectral types, as it is an M dwarf whose near edge-on disk may be directly compared to that of its A5V sibling beta Pic. We resolve the disk from 8-60 AU in the near-IR JHK' bands at high resolution with the Keck II telescope and adaptive optics, and develop a novel data reduction technique for the removal of the stellar point spread function. The point source detection sensitivity in the disk midplane is more than a magnitude less sensitive than regions away from the disk for some radii. We measure a blue color across the near-IR bands, and confirm the presence of substructure in the inner disk. Some of the structural features exhibit wavelength-dependent positions. The disk architecture and characteristics of grain composition are inferred through modeling. We approach the modeling of the dust distribution in a manner that complements previous work. Using a Monte Carlo radiative transfer code, we compare a relatively simple model of the distribution of porous grains to a broad data set, simultaneously fitting to midplane surface brightness profiles and the spectral energy distribution. Our model confirms that the large-scale architecture of the disk is consistent with detailed models of steady-state grain dynamics. Here, a belt of parent bodies from 35-40 AU is responsible for producing dust that is then swept outward by the stellar wind and radiation pressures. We infer the presence of very small grains in the outer region, down to sizes of ~0.05 micron. These sizes are consistent with stellar mass-loss rates Mdot_* << 10^2 Mdot_sun.Comment: ApJ accepted, 56 pages, preprint style. Version in emulateapj with high-resolution figures available at http://tinyurl.com/y6ent