Organic Production Enhances Milk Nutritional Quality by Shifting Fatty Acid Composition: A United States–Wide, 18-Month Study

Over the last century, intakes of omega-6 (ω-6) fatty acids in Western diets have dramatically increased, while omega-3 (ω-3) intakes have fallen. Resulting ω-6/ω-3 intake ratios have risen to nutritionally undesirable levels, generally 10 to 15, compared to a possible optimal ratio near 2.3. We report results of the first large-scale, nationwide study of fatty acids in U.S. organic and conventional milk. Averaged over 12 months, organic milk contained 25% less ω-6 fatty acids and 62% more ω-3 fatty acids than conventional milk, yielding a 2.5-fold higher ω-6/ω-3 ratio in conventional compared to organic milk (5.77 vs. 2.28). All individual ω-3 fatty acid concentrations were higher in organic milk—α-linolenic acid (by 60%), eicosapentaenoic acid (32%), and docosapentaenoic acid (19%)—as was the concentration of conjugated linoleic acid (18%). We report mostly moderate regional and seasonal variability in milk fatty acid profiles. Hypothetical diets of adult women were modeled to assess milk fatty-acid-driven differences in overall dietary ω-6/ω-3 ratios. Diets varied according to three choices: high instead of moderate dairy consumption; organic vs. conventional dairy products; and reduced vs. typical consumption of ω-6 fatty acids. The three choices together would decrease the ω-6/ω-3 ratio among adult women by ∼80% of the total decrease needed to reach a target ratio of 2.3, with relative impact “switch to low ω-6 foods” > “switch to organic dairy products” ≈ “increase consumption of conventional dairy products.” Based on recommended servings of dairy products and seafoods, dairy products supply far more α-linolenic acid than seafoods, about one-third as much eicosapentaenoic acid, and slightly more docosapentaenoic acid, but negligible docosahexaenoic acid. We conclude that consumers have viable options to reduce average ω-6/ω-3 intake ratios, thereby reducing or eliminating probable risk factors for a wide range of developmental and chronic health problems.     

Selection of Diazotrophic Bacterial Communities in Biological Sand Filter Mesocosms Used for the Treatment of Phenolic-Laden Wastewater

Agri effluents such as winery or olive mill wastewaters are characterized by high phenolic concentrations. These compounds are highly toxic and generally refractory to biodegradation. Biological sand filters (BSFs) represent inexpensive, environmentally friendly, and sustainable wastewater treatment systems which rely vastly on microbial catabolic processes. Using denaturing gradient gel electrophoresis and terminal-restriction fragment length polymorphism, this study aimed to assess the impact of increasing concentrations of synthetic phenolic-rich wastewater, ranging from 96 mg L^?1 gallic acid and 138 mg L^?1 vanillin (i.e., a total chemical oxygen demand (COD) of 234 mg L^?1) to 2,400 mg L^?1 gallic acid and 3,442 mg L^?1 vanillin (5,842 mg COD L^?1), on bacterial communities and the specific functional diazotrophic community from BSF mesocosms. This amendment procedure instigated efficient BSF phenolic removal, significant modifications of the bacterial communities, and notably led to the selection of a phenolic-resistant and less diverse diazotrophic community. This suggests that bioavailable N is crucial in the functioning of biological treatment processes involving microbial communities, and thus that functional alterations in the bacterial communities in BSFs ensure provision of sufficient bioavailable nitrogen for the degradation of wastewater with a high C/N ratio.     

Bioreactor studies predict whole microbial population dynamics in oil sands tailings ponds

Microorganisms in oil sands fluid fine tailings (FFT) are critical to biogeochemical elemental cycling as well as to the degradation of residual hydrocarbon constituents and subsequent methane and CO₂ production. Microbial activity enhances particulate matter sedimentation rates and the dewatering of FFT materials, allowing water to be recycled back into bitumen extraction. A bulk of this evidence comes from bioreactor studies and has implications for engineering and environmental management of the FFT ponds. Yet, it is largely uncertain whether such laboratory populations are representative of whole field scale microbial communities. By using population ecology tools, we compared whole microbial communities present in FFT bioreactors to reference populations existing in Syncrude's West In Pit (WIP) tailings pond. Bacteria were found to be persistent in a sulfidic zone in both the oxic and anoxic bioreactors at all occasions tested. In contrast to the WIP, archaea only became predominant in bioreactors after 300 days, at which point analysis of similarity (global R statistic p?<?0.5) revealed no significant dissimilarities between the populations present in either system. A whole community succession pattern from bacterial dominated prevalence to a new assemblage predominated by archaea was suggested. These results have implications for the stepwise development of microbial model systems for predictive management of field scale FFT basins.     

Balancing redox cofactor generation and ATP synthesis: Key microaerobic responses in thermophilic fermentations

Geobacillus thermoglucosidasius is a Gram‐positive, thermophilic bacterium capable of ethanologenic fermentation of both C5 and C6 sugars and may have possible use for commercial bioethanol production [Tang et al., 2009; Taylor et al. (2009) Trends Biotechnol 27(7): 398–405]. Little is known about the physiological changes that accompany a switch from aerobic (high redox) to microaerobic/fermentative (low redox) conditions in thermophilic organisms. The changes in the central metabolic pathways in response to a switch in redox potential were analyzed using quantitative real‐time PCR and proteomics. During low redox (fermentative) states, results indicated that glycolysis was uniformly up‐regulated, the Krebs (tricarboxylic acid or TCA) cycle non‐uniformly down‐regulated and that there was little to no change in the pentose phosphate pathway. Acetate accumulation was accounted for by strong down‐regulation of the acetate CoA ligase gene (acs) in addition to up‐regulation of the pta and ackA genes (involved in acetate production), thus conserving ATP while reducing flux through the TCA cycle. Substitution of an NADH dehydrogenase (down‐regulated) by an up‐regulated NADH:FAD oxidoreductase and up‐regulation of an ATP synthase subunit, alongside the observed shifts in the TCA cycle, suggested that an oxygen‐scavenging electron transport chain likely remained active during low redox conditions. Together with the observed up‐regulation of a glyoxalase and down‐regulation of superoxide dismutase, thought to provide protection against the accumulation of toxic phosphorylated glycolytic intermediates and reactive oxygen species, respectively, the changes observed in G. thermoglucosidasius NCIMB 11955 under conditions of aerobic‐to‐microaerobic switching were consistent with responses to low pO₂ stress. Biotechnol. Bioeng. 2013; 110: 1057–1065. © 2012 Wiley Periodicals, Inc.     

Domain organization of membrane‐bound factor VIII

Factor VIII (FVIII) is the blood coagulation protein which when defective or deficient causes for hemophilia A, a severe hereditary bleeding disorder. Activated FVIII (FVIIIa) is the cofactor to the serine protease factor IXa (FIXa) within the membrane‐bound Tenase complex, responsible for amplifying its proteolytic activity more than 100,000 times, necessary for normal clot formation. FVIII is composed of two noncovalently linked peptide chains: a light chain (LC) holding the membrane interaction sites and a heavy chain (HC) holding the main FIXa interaction sites. The interplay between the light and heavy chains (HCs) in the membrane‐bound state is critical for the biological efficiency of FVIII. Here, we present our cryo‐electron microscopy (EM) and structure analysis studies of human FVIII‐LC, when helically assembled onto negatively charged single lipid bilayer nanotubes. The resolved FVIII‐LC membrane‐bound structure supports aspects of our previously proposed FVIII structure from membrane‐bound two‐dimensional (2D) crystals, such as only the C2 domain interacts directly with the membrane. The LC is oriented differently in the FVIII membrane‐bound helical and 2D crystal structures based on EM data, and the existing X‐ray structures. This flexibility of the FVIII‐LC domain organization in different states is discussed in the light of the FVIIIa–FIXa complex assembly and function. © 2013 Wiley Periodicals, Inc. Biopolymers 99: 448–459, 2013.     

Liver in a dish

There exists a worldwide shortage of donor livers for transplant. This may not pose a problem in the future, as Takebe et al. have recently grown functional “liver buds” from stem cells in a dish.Since the discovery of human induced pluripotent stem cells (hiPSCs), the promise of generating organs from patients'' iPSCs has received considerable attention as an alternative to donor organ transplantation. Over the past few years, much progress has been made in the differentiation of various somatic cell types from human pluripotent stem cells (hPSCs). However, only a limited number of reports have described the generation of three-dimensional organoids from human stem cells in vitro, including the optic cup¹, the pituitary epithelium², and from adult stem cells — the gut epithelium³. These experimental systems share several common features: 1) they all begin with ES cells or adult stem cells, 2) the cells grow as floating aggregates, and 3) all three organoids (optic cup, pituitary epithelium, and gut crypt) are epithelial structures⁴. In addition, one particularly unexpected finding has emerged from each of these experiments, namely that a high level of self-organization seems to play a substantial role in establishing local tissue architecture and assembly of the resulting organoid.Despite these remarkable examples of organogenesis in vitro, the likelihood of growing a complex vascularized organ in dish, such as liver, has seemed less plausible. Takebe et al.⁵ have made the implausible possible by focusing on the first steps of organogenesis, namely the cellular interactions that occur during liver bud development. The earliest stage of liver organogenesis involves the outgrowth of a group of endodermal and mesenchymal cells from the posterior foregut that soon thereafter become vascularized to form a liver bud. During these morphogenetic changes, a key element to the formation of a liver bud is the orchestration of signals between three types of cells: liver, mesenchymal and endothelial progenitors. Takebe et al. posited that they might be able to recapitulate liver bud formation in vitro by mixing hepatic endoderm cells together with endothelial and mesenchymal cells. To test this idea, they prepared hepatic endoderm cells (hiPSC-HEs) from hiPSCs by directed differentiation, and then co-cultured them with human umbilical vein endothelial cells (HUVECs) and human mesenchymal stem cells (MSCs). Two days later, the cells had self-assembled into a 5-mm-long, three-dimensional tissue that was reminiscent of “liver bud” structures in vivo. To further mature these hiPSC-derived “liver buds” (hiPSC-LBs), they transplanted them into immune-compromised mice where the hiPSC-LBs connected with the host vasculature within 48 h and formed functional vascular networks similar in density and morphology to those of human adult livers. Transplanted hiPSC-LBs started functioning about 10 days later, producing human albumin and metabolizing drugs in a similar fashion to human liver. Perhaps most remarkably, Takebe et al. demonstrated that these hiPSC-LBs could rescue liver function when transplanted to mice with liver failure.The differences between Takebe and his colleagues'' study and other studies designed to reproduce organogenesis in vitro are that they started with several different cell types; the cells were grown initially in a two-dimensional petri dish; and the result was a solid liver organoid that can be vascularized and function after transplantation. For many, the most striking finding is the high level of self-organization in this experimental differentiation system. By analogy, it is equivalent to delivering all of the materials necessary to build a house to a construction site and returning several days later to find a fully assembled home. Clearly the principles of self-organization and self-assembly are playing much more profound roles during differentiation than we previously thought and it is likely what has been reported by Takebe et al. represents only the tip of the iceberg. One takeaway from the way that Takebe and his colleagues'' tackled the problem of in vitro organogenesis may be their focus on the earliest processes in organ development, as it is likely to identify the right combination of cell types for organogenesis to proceed. Nonetheless, this study has raised several new questions. How does self-organization and self-assembly occur in vitro? What is the molecular logic of this process? How can we manipulate a self-organizing system so that we might guide it in the direction we want it to go? And ultimately, could we use a similar strategy to produce other complex solid organs in vitro, e.g., lung, kidney, and pancreas?As summarized by Takebe et al., this study demonstrates a “proof-of-concept” that “organ-bud transplantation provides a promising new approach to study regenerative medicine”. However, a significant amount of work will be required before these findings can be translated into a therapy. First, these little liver buds do not form a complete adult liver. They are missing a number of critical cell types, chief among them biliary epithelial cells and thus bile ducts. How to produce a fully functional liver remains a challenge. Second, in order to translate these findings into human therapies, a key step will be to scale this process so that one can produce a liver bud large enough for transplantation into humans. Of course, there is always the question about safety when it comes to stem cell-based therapies. Undifferentiated stem cells left in transplants tend to form tumors and the use of oncogenes for iPS reprogramming needs to be resolved before iPS cells can be considered for human therapy. Despite the reality that clinical therapies based on this report remain a distant promise, it is inspirational to consider how quickly the field is moving and exciting to speculate about what might come next. If one considers that a drug has been identified to specifically eliminate pluripotent but not differentiated hPSCs⁶ and that a recent report showed that pluripotent stem cells could be induced from mouse somatic cells by using only small molecules⁷, we may have good reason to believe that one day in the not too distant future we could grow patient-customized organs for transplantation (Figure 1).Open in a separate windowFigure 1This figure outlines the strategy of generating organs from patients'' iPSCs as an alternative to transplantation. Patient-derived pluripotent stem cells (iPSCs) can be differentiated in vitro to desired cell types. As demonstrated by Takebe et al.⁵, different cell types can be co-cultured in dish to recapitulate the earliest process of organogenesis and form three-dimensional organ buds. These in vitro produced organ buds could be used for transplantation in the future.     

Intestinal Methanobrevibacter smithii but not total bacteria is related to diet‐induced weight gain in rats

It is increasingly understood that gastrointestinal (GI) methanogens, including Methanobrevibacter smithii, influence host metabolism.

Objective:

Therefore, we compared M. smithii colonization and weight gain in a rat model under different dietary conditions.

Design and Methods:

Sprague‐Dawley rats were inoculated with M. smithii or vehicle (N = 10/group), fed normal chow until day 112 postinoculation, high‐fat chow until day 182, then normal chow until day 253. Thereafter, five rats from each group were fed high‐fat and normal chow until euthanasia.

Results:

Both groups exhibited M. smithii colonization, which increased following inoculation only for the first 9 days. Change to high‐fat chow correlated with significant increases in weight (P < 0.00001) and stool M. smithii (P < 0.01) in all rats, with stool M. smithi decreasing on return to normal chow. Rats switched back to high‐fat on day 253 further increased weight (P < 0.001) and stool M. smithii (P = 0.039). Euthanasia revealed all animals had higher M. smithii, but not total bacteria, in the small intestine than in the colon. Rats switched back to high‐fat chow had higher M. smithii levels in the duodenum, ileum, and cecum than those fed normal chow; total bacteria did not differ in any bowel segment. Rats which gained more weight had more bowel segments colonized, and the lowest weight recorded was in a rat on high‐fat chow which had minimal M. smithii colonization.

Conclusions:

We conclude that M. smithii colonization occurs in the small bowel as well as in the colon, and that the level and extent of M. smithii colonization is predictive of degree of weight gain in this animal model.