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1.
Growth of mastitis pathogenic bacteria was measured in bovine whey samples by a turbidometric microtechnique. Whey from mastitis cows supported growth as compared with whey prepared from normal milk. Blood proteins leak into milk during mastitis. A study was undertaken to analyze which molecules from blood would promote bacterial growth in whey Fractions containing hemoglobin showed a distinct growth-promoting effect. An inadequate iron supply is one of the restricting growth factors for bacteria in milk. By utilizing heme-compounds the pathogens can by-pass the effect of antimicrobial iron-binding present in milk in the form of lactoferrin. 相似文献
2.
Traditionally, locally calibrated soil tests were used for fertilizer and lime recommendations. Farmers and advisors are increasingly using new ‘universal’ soil tests without local calibration. The objective of this study was to compare five commercially available soil tests and to determine whether they would provide similar recommendations. In total, 24 fields in Western Finland were sampled for 4 years while being treated with fertilizers, lime and manure. The soil samples were analysed with Mehlich-3, ammonium acetate, H3A, hydrochloric acid and mild acetic acid (Spurway) extractants. In addition, Soil Health Tool (CO2 burst, water-soluble C and N) and tissue testing were conducted. The different tests extracted different orders of magnitude of nutrients (especially P and Mg), but the results from the different extractions were correlated. Mehlich-3 degree of phosphorus saturation (DPS) presented a threshold, below which soluble phosphorus was not detected. Similar thresholds were found for P, S and Mg. Mehlich-3 and ammonium acetate provided similar results for Ca, Mg and K and can be used interchangeably for liming recommendations. Mehlich-3 identified more fields with Zn, Cu, B and S deficiencies and less fields with Mn deficiencies compared with ammonium acetate + EDTA and tissue testing. The tests had strong correlation, but the determination of nutrient deficiencies needs local calibration of deficiency limits. 相似文献
3.
Experimental mastitis was induced in cows by intramammary infusion of endotoxin, Staphylococcus aureus or Streptococcus agalactiae. The inflammatory response was monitored by somatic cell counting and N-acetyl-beta-D-glucosaminidase (NAGase). NAGase activity was analysed in fresh milk samples in parallel with samples treated by a cycle of freezing and thawing combined with detergent treatment to release the cell-bound NAGase. Before the udder reacted by inflammation, the total NAGase activity consisted of free extracellular activity. Later on when the inflammation was established, much of the milk NAGase remained sequestered intracellularly. S agalactiae was linked with a high degree of cellular NAGase sequestration indicating a blockage of the lysosomal release function from the phagocytes. S aureus delayed the inflammatory response. 相似文献
4.
Honey bee queens mate with many males, creating numerous patrilines within colonies that are genetically distinct. The effects of genetic diversity on colony productivity and long-term fitness are unknown. We show that swarms from genetically diverse colonies (15 patrilines per colony) founded new colonies faster than swarms from genetically uniform colonies (1 patriline per colony). Accumulated differences in foraging rates, food storage, and population growth led to impressive boosts in the fitness (i.e., drone production and winter survival) of genetically diverse colonies. These results further our understanding of the origins of polyandry in honey bees and its benefits for colony performance. 相似文献
5.
Smartt SJ Maund JR Hendry MA Tout CA Gilmore GF Mattila S Benn CR 《Science (New York, N.Y.)》2004,303(5657):499-503
We present the discovery of a red supergiant star that exploded as supernova 2003gd in the nearby spiral galaxy M74. The Hubble Space Telescope (HST) and the Gemini Telescope imaged this galaxy 6 to 9 months before the supernova explosion, and subsequent HST images confirm the positional coincidence of the supernova with a single resolved star that is a red supergiant of 8(+4)(-2) solar masses. This confirms both stellar evolution models and supernova theories predicting that cool red supergiants are the immediate progenitor stars of type II-plateau supernovae. 相似文献
6.
In-line connected electrochemical (EC) and diode array (DAD) detectors were compared in the reversed-phase high-performance liquid chromatographic (RP-HPLC) analysis of coenzymes Q(9) and Q(10) in some food materials (beef steak, beef heart, Baltic herring fillet, and rye flour). Coenzymes Q(9) and Q(10) were extracted from the samples using a 5:1 n-hexane-ethanol mixture. Coefficient of variation (CV%) of quadruplicate or quintuplicate determined samples for coenzymes Q(9) and Q(10) was <10 by both EC detector and DAD. Responses of the detection systems were linear in the range evaluated, 10-200 ng/injection, and had correlation coefficients exceeding 0.999. Recoveries of added coenzymes Q(9) and Q(10) varied 73-105% for DAD and 74-103% for EC detector, respectively. Detection limits for coenzymes Q(9) and Q(10) using the DAD system were 4 and 6 ng/injection, respectively, and 0.2 and 0.3 ng/injection by EC detection. Results derived from the two detection systems were generally similar. However, although EC detector was 20-fold more sensitive, the selectivity was, in some cases, poorer than that of DAD. 相似文献
7.
8.
T Mattila J Syv?j?rvi N E Jensen M Sandholm 《American journal of veterinary research》1986,47(1):139-142
Interrelationships between N-acetyl-beta-D-glucosaminidase (indicating cellular damage) and antitrypsin (indicating increased permeability between the blood and milk compartments) were evaluated in 1,411 quarter-milk samples collected during routine herd surveys. N-Acetyl-beta-D-glucosaminidase was antitrypsin, whereas, in more severe mastitis, antitrypsin had a more constant deflection. The sensitivity of both determinants was associated with the virulence of bacteria. Production of bacterial hemolytic toxins was associated with a significant increase in both determinants. Penicillinase production by staphylococci was associated with selective increases of antitrypsin. 相似文献
9.
10.
Growth of Escherichia coli and Staphylococcus aureus was analyzed by turbidometry in 456 selected whey samples. The samples had been graded mastitic or nonmastitic as determined by antitrypsin assay and bacteriologic examination. Whey samples from inflamed quarters (antitrypsin increased) and infected quarters significantly promoted bacterial growth as compared with whey samples from control quarters. The growth-stimulatory effect was limited to the diseased quarters, since control quarters from the same animals did not support enhanced bacterial growth. The observations indicate that in chronic mastitis, the inflammatory process leads to changes in the whey that promote bacterial growth in vitro. 相似文献