Effect of feeding biotin on milk production and hoof health in lactating dairy cows: a quantitative assessment

Objectives of this study were to critically review randomized controlled trials, evaluate the effectiveness of supplementation with biotin on milk yield and composition and hoof health in lactating dairy cows, explore sources of heterogeneity among studies, and evaluate publication bias. Quantitative assessments can increase the statistical power with which we study the effect of treatments, such as biotin, on outcomes. A total of 9 papers, with 6 production and 3 hoof health studies, met the eligibility criteria for meta-analysis. Eight studies evaluated various hoof lesions in biotin-supplemented cows that did not meet the inclusion criteria. Eleven comparisons were made of milk production responses to biotin treatment. Data extracted included the number of cows in control and treatment groups, measures of variance of responses (standard error or standard deviation) and P-values. Other data obtained included the duration of treatment before and after calving, parity, breed of cow, type and dose of biotin, delivery method of supplementation, and types of diets. Biotin increased milk production by 1.29 kg per head per day (95% confidence interval = 0.35 to 2.18 kg) with no evidence of heterogeneity (I² = 0.0%). Treatment did not affect milk fat or protein percentages, and a trend to increase fat and protein yields was observed. Milk production and composition results were not influenced by duration of treatment before calving, parity, or diet type. Assessment of biotin supplementation on hoof health indicated that more studies had improved rather than negative or neutral outcomes. The effect of biotin treatment on milk production was relatively large and the effects on fat and protein yields, although not significant, were consistent in direction and magnitude with the milk response. The hoof health responses to biotin should encourage further studies to more effectively define the nature of these responses using consistent criteria for examination of hoof conditions and lameness.     

BIOTIN-ACTIVE COMPOUNDS,THEIR EXISTENCE IN NATURE AND THE BIOTIN REQUIREMENTS OF YEASTS

After a short account of the discovery of biotin and the progress of early biotin research, the natural occurrence of biotin with particular consideration to the raw materials used in the fermentation industry and its products is described. Of the many known biotin derivatives, those appearing in nature and those which can be converted to biotin-active (or inactive) compounds by simple procedures are reported. Ways to by-pass the need for biotin in microbes is discussed. The importance of biotin in yeast production, the biotin requirements of yeast, and the effect of culture conditions on these requirements are reported. The close relationship between the participation of biotinylenzymes and the biotin requirements is noted.     

Biotinylated bi- and tetra-antennary glycoconjugates for Escherichia coli detection

Glycans cover the surface of all mammalian cells. Several toxins and pathogens use these glycans to bind and infect the cell. Using a versatile modular synthetic strategy, we have developed biotinylated bi- and tetraantennary glycoconjugates to capture and detect E. coli and compared the capturing ability of these molecules to commercial polyclonal antibodies. Magnetic beads were coated with biotinylated glycoconjugate or antibody, and these beads were used to capture, isolate, and quantify bacterial recovery by using a luminescence assay. The glycoconjugate-coated magnetic beads outperformed antibody-coated magnetic beads in sensitivity and selectivity when compared under identical experimental conditions. Glycoconjugates could capture Escherichia coli from stagnant water, and the ability of a panel of glycoconjugates to capture a selection of pathogenic bacteria was also evaluated. To the best of our knowledge, this study represents the first comprehensive study that compares synthetic glycoconjugates and antibodies for E. coli detection. The glycoconjugates are also very stable and inexpensive. The results presented here are expected to lead to an increased interest in developing glycoconjugate-based high affinity reagents for diagnostics.     

Molecular recognition imaging using tuning fork-based transverse dynamic force microscopy

We demonstrate simultaneous transverse dynamic force microscopy and molecular recognition imaging using tuning forks as piezoelectric sensors. Tapered aluminum-coated glass fibers were chemically functionalized with biotin and anti-lysozyme molecules and attached to one of the prongs of a 32 kHz tuning fork. The lateral oscillation amplitude of the tuning fork was used as feedback signal for topographical imaging of avidin aggregates and lysozyme molecules on mica substrate. The phase difference between the excitation and detection signals of the tuning fork provided molecular recognition between avidin/biotin or lysozyme/anti-lysozyme. Aggregates of avidin and lysozyme molecules appeared as features with heights of 1–4 nm in the topographic images, consistent with single molecule atomic force microscopy imaging. Recognition events between avidin/biotin or lysozyme/anti-lysozyme were detected in the phase image at high signal-to-noise ratio with phase shifts of 1–2°. Because tapered glass fibers and shear-force microscopy based on tuning forks are commonly used for near-field scanning optical microscopy (NSOM), these results open the door to the exciting possibility of combining optical, topographic and biochemical recognition at the nanometer scale in a single measurement and in liquid conditions.     

生物素中间体化合物（Ⅰ）的测定方法

采用高碘酸钾法定量测定了生物素合成中间体化合物（Ⅰ）的含量,分析结果用红外光谱法作了对照,结果表明该方法准确可靠．将其用于生物素合成的监控分析,对提高生物素产品的质量和产率有着十分重要的作用．