5,054 research outputs found

    Genetic analysis of milk urea nitrogen and relationships with yield and fertility across lactation

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    AbstractThe aim of this project was to investigate the relationship of milk urea nitrogen (MUN) with 3 milk production traits [milk yield (MY), fat yield (FY), protein yield (PY)] and 6 fertility measures (number of inseminations, calving interval, interval from calving to first insemination, interval from calving to last insemination, interval from first to last insemination, and pregnancy at first insemination). Data consisted of 635,289 test-day records of MY, FY, PY, and MUN on 76,959 first-lactation Swedish Holstein cows calving from 2001 to 2003, and corresponding lactation records for the fertility traits. Yields and MUN were analyzed with a random regression model followed by a multi-trait model in which the lactation was broken into 10 monthly periods. Heritability for MUN was stable across lactation (between 0.16 and 0.18), whereas MY, FY, and PY had low heritability at the beginning of lactation, which increased with time and stabilized after 100 d in milk, at 0.47, 0.36, and 0.44, respectively. Fertility traits had low heritabilities (0.02 to 0.05). Phenotypic correlations of MUN and milk production traits were between 0.13 (beginning of lactation) and 0.00 (end of lactation). Genetic correlations of MUN and MY, FY, and PY followed similar trends and were positive (0.22) at the beginning and negative (Ôłĺ0.15) at the end of lactation. Phenotypic correlations of MUN and fertility were close to zero. A surprising result was that genetic correlations of MUN and fertility traits suggest a positive relationship between the 2 traits for most of the lactation, indicating that animals with breeding values for increased MUN also had breeding values for improved fertility. This result was obtained with a random regression model as well as with a multi-trait model. The analyzed group of cows had a moderate level of MUN concentration. In such a population MUN concentration may increase slightly due to selection for improved fertility. Conversely, selection for increased MUN concentration may improve fertility slightly

    Microwave Spectroscopy

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    Contains reports on two research projects.Joint Services Electronics Programs (U.S. Army, U.S. Navy, and U.S. Air Force) under Contract DA 28-043-AMC-02536(E

    Antibiotic Potential and Biophysical Characterization of Amphipathic ╬▓-Stranded [XZ]n Peptides With Alternating Cationic and Hydrophobic Residues

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    Cationic membrane-active peptides are considered to be promising candidates for antibiotic treatment. Many natural and artificial sequences show an antimicrobial activity when they are able to take on an amphipathic fold upon membrane binding, which in turn perturbs the integrity of the lipid bilayer. Most known structures are ╬▒-helices and ╬▓-hairpins, but also cyclic knots and other irregular conformations are known. Linear ╬▓-stranded antimicrobial peptides are not so common in nature, but numerous model sequences have been designed. Interestingly, many of them tend to be highly membranolytic, but also have a significant tendency to self-assemble into ╬▓-sheets by hydrogen-bonding. In this minireview we examine the literature on such amphipathic peptides consisting of simple repetitive sequences of alternating cationic and hydrophobic residues, and discuss their advantages and disadvantages. Their interactions with lipids have been characterized with a number of biophysical techniquesÔÇöespecially circular dichroism, fluorescence, and infraredÔÇöin order to determine their secondary structure, membrane binding, aggregation tendency, and ability to permeabilize vesicles. Their activities against bacteria, biofilms, erythrocytes, and human cells have also been studied using biological assays. In line with the main scope of this Special Issue, we attempt to correlate the biophysical results with the biological data, and in particular we discuss which properties (length, charge, aggregation tendency, etc.) of these simple model peptides are most relevant for their biological function. The overview presented here offers ideas for future experiments, and also suggests a few design rules for promising ╬▓-stranded peptides to develop efficient antimicrobial agents

    Self-Perception of Economic Means is Associated with Dietary Choices, Diet Quality and Physical Health in the Oldest Old Men from the Highest Socioeconomic Group

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    IntroductionSelf-perception of economic means may affect dietary choices, diet quality, and health behavior. We examined these associations in the oldest-old men from the highest socioeconomic class.MethodsThe participants in this cross-sectional analysis were the oldest- old home-dwelling men (n = 314, mean age 87 years, range 82-97 years) from the longitudinal Helsinki Businessmen Study cohort. They responded to a postal health and nutrition questionnaire, whereupon dietary intakes were assessed using 3-day food diaries and two diet quality indices. The questionnaire also included items about health, exercise, falls, and economic means.ResultsHigher self-perception of economic means was linearly associated with higher fish intake (p = 0.021), fruit and vegetable intakes (p = 0.027), use of alcohol (p = 0.003), overall diet quality according to IDQ (p = 0.008), self-perceived physical condition (p = 0.002) and inversely associated with body weight (p = 0.011), weight loss (p = 0.008), blood glucose levels (p = 0.020), and falls (p = 0.029).ConclusionSelf-perception of economic means was associated with dietary choices and physical health even among affluent older men. This information is important, because self-perception of economic means, however real, may affect health and nutrition behavior of older people.Peer reviewe

    3D Hydrophobic Moment Vectors as a Tool to Characterize the Surface Polarity of Amphiphilic Peptides

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    AbstractThe interaction of membranes with peptides and proteins is largely determined by their amphiphilic character. Hydrophobic moments of helical segments are commonly derived from their two-dimensional helical wheel projections, and the same is true for ╬▓-sheets. However, to the best of our knowledge, there exists no method to describe structures in three dimensions or molecules with irregular shape. Here, we define the hydrophobic moment of a molecule as a vector in three dimensions by evaluating the surface distribution of all hydrophilic and lipophilic regions over any given shape. The electrostatic potential on the molecular surface is calculated based on the atomic point charges. The resulting hydrophobic moment vector is specific for the instantaneous conformation, and it takes into account all structural characteristics of the molecule, e.g., partial unfolding, bending, and side-chain torsion angles. Extended all-atom molecular dynamics simulations are then used to calculate the equilibrium hydrophobic moments for two antimicrobial peptides, gramicidin S and PGLa, under different conditions. We show that their effective hydrophobic moment vectors reflect the distribution of polar and nonpolar patches on the molecular surface and the calculated electrostatic surface potential. A comparison of simulations in solution and in lipid membranes shows how the peptides undergo internal conformational rearrangement upon binding to the bilayer surface. A good correlation with solid-state NMR data indicates that the hydrophobic moment vector can be used to predict the membrane binding geometry of peptides. This method is available as a web application on http://www.ibg.kit.edu/HM/

    Synergistic Insertion of Antimicrobial Magainin-Family Peptides in Membranes Depends on the Lipid Spontaneous Curvature

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    AbstractPGLa and magainin 2 (MAG2) are amphiphilic antimicrobial peptides from frog skin with known synergistic activity. The orientation of the two helices in membranes was studied using solid-state 15N-NMR, for each peptide alone and for a 1:1 mixture of the peptides, in a range of different lipid systems. Two types of orientational behavior emerged. 1), In lipids with negative spontaneous curvature, both peptides remain flat on the membrane surface, when assessed both alone and in a 1:1 mixture. 2), In lipids with positive spontaneous curvature, PGLa alone assumes a tilted orientation but inserts into the bilayer in a transmembrane alignment in the presence of MAG2, whereas MAG2 stays on the surface or gets only slightly tilted, when observed both alone and in the presence of PGLa. The behavior of PGLa alone is identical to that of another antimicrobial peptide, MSI-103, in the same lipid systems, indicating that the curvature-dependent helix orientation is a general feature of membrane-bound peptides and also influences their synergistic intermolecular interactions

    Microwave Spectroscopy

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    Contains research objectives and reports on three research projects.Joint Services Electronics Programs (U. S. Army, U.S. Navy, and U.S. Air Force) under Contract DA 36-039-AMC-03200(E
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