A high peak brilliance, laser-based Compton-scattering γ -ray source, capable of producing quasimonoenergetic photons with energies ranging from 0.1 to 0.9 MeV has been recently developed and used to ...perform nuclear resonance fluorescence (NRF) experiments. Techniques for characterization of γ -ray beam parameters are presented. The key source parameters are the size (0.01mm2 ), horizontal and vertical divergence (6×10mrad2 ), duration (16 ps), and spectrum and intensity (105photons/shot ). These parameters are summarized by the peak brilliance, 1.5×1015photons/mm2/mrad2/s/0.1% bandwidth, measured at 478 keV. Additional measurements of the flux as a function of the timing difference between the drive laser pulse and the relativistic photoelectron bunch, γ -ray beam profile, and background evaluations are presented. These results are systematically compared to theoretical models and computer simulations. NRF measurements performed on Li7 in LiH demonstrate the potential of Compton-scattering photon sources to accurately detect isotopes in situ.
The question of bioaccessibility of nutrients within a food matrix has become of increasing interest in the fields of nutrition and food science as bioaccessibility is the precursor to ...bioavailability. By analyzing the propagation of the wetting front of acidic water in raw carrot core and Edam cheese as model systems, we show that the diffusion of the acidic water is dependent on the pH of the gastric fluid and the food matrix. In addition, we demonstrate that the diffusion of NaCl during cheese brining is also dependent upon the concentration of the NaCl. This demonstrates that Fickian diffusion, along with a concentration dependent diffusion coefficient, is a valid model for describing concentration profiles in multiple food systems.
Utilizing the diffusion rates found at various pH levels (1.50, 2.00, 3.50, 4.30, 5.25 and 7.00), we developed a model to describe the measured non-linear rate of soluble solid loss during digestion at various constant pH levels. Additionally, we have developed a model to predict the likely rate of soluble solid loss during digestion in the stomach where pH decreases with time. This model can be used to help understand and optimize the relationship between food structure/composition and food degradation in the human stomach, which may help in the development of novel foods with desired functionality.
•Diffusion of NaCl during cheese brining is concentration dependent.•Diffusion of gastric fluid in carrot and cheese is dependent on pH and structure.•We developed a model of pH-dependent soluble particle loss during digestion.•The model specifies the relationship between food structure and food degradation.•This helps in the development of novel foods with desired functionality.
The gastrointestinal microbiota plays an important role in maintaining host health by preventing the colonization of pathogens, fermenting dietary compounds, and maintaining normal mucosal immunity. ...Particularly in early life, the composition of the microbiota profoundly influences the development and maturation of the gastrointestinal tract (GIT) mucosa, which may affect health in later life. Therefore, strategies to manipulate the microbiota during infancy may prevent the development of some diseases later in adult life. Earlier research suggested that term fetuses are sterile and that the initial bacterial colonization of the newborn GIT occurs only after the baby transits through the birth canal. However, recent studies have demonstrated that the colonization and/or contact of the fetus with the maternal GIT microbiota may start in utero. After vaginal birth, the colonization of the neonate GIT continues through contact with maternal feces and vaginal bacteria, leading to a relatively simple microbial community that is influenced by feeding type (breast vs. formula feeding). Maternal GIT microbiota, vaginal microbiota, and breast milk composition are influenced by maternal diet. Alterations of the maternal GIT microbiota composition via supplementation with probiotics and prebiotics have been shown; however, transfer of these benefits to the offspring remains to be demonstrated. This review focuses on the influence of maternal GIT microbiota during the pre- and postpartum periods on the colonization of the infant GIT. In particular, it examines the manipulation of the maternal GIT microbiota composition through the use of probiotics and/or prebiotics and subsequent consequences for the health of the offspring.
The galactopoietic effect of growth hormone (GH) in lactating ruminants is well established; however the mechanisms that mediate these effects are not well understood. The first objective of this ...study was to determine the effect of GH on the synthesis of the major casein and whey proteins. The second objective was to identify the genes and pathways that may be involved in mediating the effect of GH on milk synthesis. A single subcutaneous injection of a commercially available slow release formulation of GH (Lactatropin®), or physiological saline solution (control) was administered to non-pregnant dairy cows (n=4/group) in mid-late lactation. Milk samples were collected for composition analysis and mammary lobulo-alveolar tissue was collected postmortem 6 days post injection. Gene expression profiles were evaluated using either a 22 000 bovine complementary DNA microarray or quantitative PCR (qPCR), and microarrays were validated by qPCR. The yield of all the major casein and whey proteins was increased 32% to 41% in GH-treated cows, with the exception of α-lactalbumin yield which was elevated by 70% relative to controls. Treatment with GH treatment tended to increase the concentration of α-lactalbumin but had no effect on the concentration of any of the major milk proteins. Messenger RNA (mRNA) abundance of the major whey and casein genes, with the exception of α-s2-casein, was increased in response to GH compared with controls, which is consistent with the positive effect of GH on milk production. Treatment with GH treatment influenced the mRNA abundance of genes involved in cell growth and proliferation, transcriptional and translational regulation, actin cytoskeleton signalling, lipid metabolism and cell death. This study has provided new insights into the cell signalling that may be involved in mediating the effect of GH on milk production in the mammary gland of lactating dairy cows.
A monoenergetic gamma-ray (MEGa-ray) source based on Compton scattering, targeting nuclear physics applications such as nuclear resonance fluorescence, has been constructed and commissioned at ...Lawrence Livermore National Laboratory. In this paper, the overall architecture of the system, as well as some of the design decisions (such as laser pulse lengths and interaction geometry) made in the development of the source, are discussed. The performances of the two laser systems (one for electron production, one for scattering), the electron photoinjector, and the linear accelerator are also detailed, and initial γ -ray results are presented.
Proanthocyanidins (PA), also known as condensed tannins, belong to the oldest of plant secondary metabolites. These compounds are widespread in woody plants, but are also found in certain forages. ...Proanthocyanidins can exert effects in organisms because of their ability to complex with proteins. Forages containing moderate concentrations of PA (2–4% DM) can exert beneficial effects on protein metabolism in sheep, slowing degradation of dietary protein to ammonia by rumen micro-organisms and increasing protein outflow from the rumen, thus increasing absorption of amino acids in the small intestine of the animal. This was shown to result in increases in lactation, wool growth and liveweight gain, without changing voluntary feed intake. Dietary PA can also contribute to improved animal health by reducing the detrimental effects of internal parasites in sheep and the risk of bloat in cattle. In contrast, high dietary PA concentrations (6–12% DM) depress voluntary feed intake, digestive efficiency and animal productivity.
Temperate forages containing PA, such as
Lotus corniculatus and
L. pedunculatus, will not persist in intensive grazing systems if continuously grazed (i.e. set stocked), especially in mixtures with perennial ryegrass and white clover and need to be grown as pure species and rotationally grazed. Nevertheless, inputs of these ‘special purpose’forages can increase sustainability and productivity in intensive grazing systems through increasing the efficiency of animal production, reducing urinary nitrogen (N) excretion and reducing chemical inputs as anthelmintics and as detergents used to control rumen bloat in cattle.
Proanthocyanidins are derived from the flavonoid biosynthesis pathway, and knowledge is rapidly increasing about the molecular control of PA biosynthesis. These recent investigations may ultimately enable the expression by genetic engineering of increased levels of PA in the leaves of agriculturally important forage plants such as white clover and perennial rye grass, which will withstand continuous defoliation under grazing and currently contain only trace amounts of PA. This could potentially lead to the widespread use of PA in temperate grazing systems. Further consideration, should now be given to long-term adaptations in the animal, and to ecological effects on the soil ecosystem by PA and their degradation products excreted in animal faeces. More information is required in particular on the effects of PA on soil nitrification, ammonia volatilisation from soil, and nitrogen levels in the groundwater.
Condensed tannins in forage legumes improve the nutrition of sheep by reducing ruminal degradation of plant protein and increasing crude protein flow to the intestine. However, the effects of ...condensed tannins in forage legumes on rumen bacterial populations in vivo are poorly understood. The aim of this study was to investigate the specific effects of condensed tannins from Lotus corniculatus on four proteolytic rumen bacteria in sheep during and after transition from a ryegrass (Lolium perenne) white clover (Trifolium repens) diet (i.e., low condensed tannins) to a Lotus corniculatus diet (i.e., higher condensed tannins). The bacterial populations were quantified using a competitive polymerase chain reaction. Lotus corniculatus was fed with or without ruminal infusions of polyethylene glycol (PEG), which binds to and inactivates condensed tannins, enabling the effect of condensed tannins on bacterial populations to be examined. When sheep fed on ryegrass white clover, populations of Clostridium proteoclasticum B316
T
, Butyrivibrio fibrisolvens C211a, Eubacterium sp. C12b, and Streptococcus bovis B315 were 1.5 × 10
8
, 1.1 × 10
6
, 4.6 × 10
8
, and 7.1 × 10
6
mL
1
, respectively. When the diet was changed to Lotus corniculatus, the average populations (after 8120 h) of C. proteoclasticum, B. fibrisolvens, Eubacterium sp., and S. bovis decreased (P < 0.001) to 2.4 × 10
7
, 1.1 × 10
5
, 1.1 × 10
8
, and 2.5 × 10
5
mL
1
, respectively. When PEG was infused into the rumen of sheep fed Lotus corniculatus, the populations of C. proteoclasticum, B. fibrisolvens, Eubacterium sp., and S. bovis were higher (P < 0.010.001) than in sheep fed Lotus corniculatus without the PEG infusion, with average populations (after 8120 h) of 4.9 × 10
7
, 3.8 × 10
5
, 1.9 ×10
8
, and 1.0 ×10
6
, respectively. Sheep fed the Lotus corniculatus diet had lower rumen proteinase activity, ammonia, and soluble nitrogen (P < 0.050.001) than sheep that were fed Lotus corniculatus plus PEG. The Lotus corniculatus diet reduced rumen nitrogen digestibility (P < 0.05) and ammonia pool size and increased the flow of undegraded feed nitrogen to the abomasum. The nitrogen intake, rumen non-ammonia nitrogen pool size, rumen microbial non-ammonia nitrogen pool size, and abomasal microbial non-ammonia nitrogen fluxes were similar both in sheep fed only Lotus corniculatus and in sheep fed Lotus corniculatus plus PEG, but nonmicrobial non-ammonia nitrogen flux to the abomasum was higher (P < 0.01) for the sheep fed only Lotus corniculatus. Although condensed tannins in Lotus corniculatus reduced the populations of some proteolytic bacteria, total ruminal microbial protein and microbial protein outflow to the abomasum were unchanged, suggesting a species-specific effect of condensed tannins on bacteria in the rumen.
Key words: condensed, tannin, rumen, bacteria, PCR.
Milk and dairy products that are tailored to meet specific nutritional requirements will become more attractive and valuable to major groups of consumers if they can serve as delivery systems for ...health-promoting nutrients. Nutritional improvement of milk is achievable in several ways, preferably by making the desirable changes
in vivo and on-farm to directly enhance the food without the need for subsequent manipulations. Methods that suit typical pastoral farming practices include trait selection for desirable phenotypes, specialised diets, long-acting parenteral supplements and modification of the ruminal flora. Successful techniques to increase concentrations of calcium, selenium, iodine, iron and cobalt/Vitamin B
12 in milk are described. However, changing composition is only one step to bringing new foods to market, as their commercial realisation will require the initiative and collaboration of scientists, veterinarians, primary producers and processors responding to market demands. Uptake of future biotechnologies to capture more value inside the farm gate will also be required if dairy industries are to remain competitive.
•Myosin loss may diminish muscle fiber performance with aging, disuse, and disease.•Computational models of myosin loss reduced cross-bridge number and fiber force.•Random myosin loss resulted in a ...smaller fiber force decrements than uniform loss.•Myosin attachment time and cross-bridge binding increased with random myosin.•Results support prior findings in heart failure patients with random myosin loss.
Diminished skeletal muscle performance with aging, disuse, and disease may be partially attributed to the loss of myofilament proteins. Several laboratories have found a disproportionate loss of myosin protein content relative to other myofilament proteins, but due to methodological limitations, the structural manifestation of this protein loss is unknown. To investigate how variations in myosin content affect ensemble cross-bridge behavior and force production we simulated muscle contraction in the half-sarcomere as myosin was removed either (i) uniformly, from the Z-line end of thick-filaments, or (ii) randomly, along the length of thick-filaments. Uniform myosin removal decreased force production, showing a slightly steeper force-to-myosin content relationship than the 1:1 relationship that would be expected from the loss of cross-bridges. Random myosin removal also decreased force production, but this decrease was less than observed with uniform myosin loss, largely due to increased myosin attachment time (ton) and fractional cross-bridge binding with random myosin loss. These findings support our prior observations that prolonged ton may augment force production in single fibers with randomly reduced myosin content from chronic heart failure patients. These simulations also illustrate that the pattern of myosin loss along thick-filaments influences ensemble cross-bridge behavior and maintenance of force throughout the sarcomere.
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