Effects of Pasteurella haemolytica A1 culture supernatant on mechanisms controlling bovine alveolar macrophage oxygen radical production.

Pasteurella haemolytica A1 culture supernatant containing leukotoxin, and modifiers of cyclic nucleotide and arachidonate metabolism, were evaluated for their ability to alter oxygen radical production by pulmonary alveolar macrophages obtained from seven Holstein calves. Calves were sedated, and underwent bronchoalveolar lavage to harvest macrophages, which were then incubated with culture supernatant and/or the drugs and toxins under study, and challenged with opsonized zymosan to induce oxygen radical generation. This was measured by a chemiluminescence technique. Pasteurella haemolytica A1 culture supernatant alone delayed the time to maximum oxygen radical production, although total production was increased. The cyclooxygenase inhibitor indomethacin and the phospholipase inhibitor p-bromophenacyl bromide significantly reduced maximum oxygen radical production, but their effects were diminished in the presence of culture supernatant. Although forskolin markedly inhibited oxygen radical generation, this effect was not altered by culture supernatant. Incubation of macrophages with pertussis toxin had no effect on oxygen radical production, while incubation with cholera toxin did inhibit production. This inhibitory effect was significantly lessened by concurrent incubation with P. haemolytica A1 culture supernatant.     

Pollination effects on fruit production of ‘Star Ruby’ grapefruit (Citrus paradisi Macf.)

Flowers of ‘Star Ruby’ grapefruit were hand-pollinated with ‘Valencia’ orange (C. sinensis (L.) Osbeck), ‘Marrs’ orange, ‘Ruby Red’ grapefruit (C. paradisi Macf.) and ‘Star Ruby’ grapefruit pollen. Flowers cross-pollinated with ‘Ruby Red’ pollen produced more fruit than did self-pollinated flowers. Flowers cross-pollinated with either ‘Marrs’ or ‘Valencia’ pollen did not produce as many fruit as ‘Ruby Red’-pollinated flowers, nor did they produce more fruit than self-pollinated or open-pollinated flowers. Few fruit were produced when ‘Star Ruby’ flowers were not hand-pollinated. Less than 0.5% of ‘Star Ruby’ pollen germinated in 15–25% sucrose solutions, whereas between 6 and 21% of the pollen from ‘Valencia’, ‘Marrs’ and ‘Ruby Red’ germinated. The number of fully-developed seeds per fruit was increased only when ‘Marrs’ pollen was used. These data show that ‘Star Ruby’ produces very little functional pollen and few functional ovules, and suggests that ‘Star Ruby’ has weak parthenocarpic ability.     

Workshop studies with monoclonal antibodies identifying a novel porcine differentiation antigen, SWC9

Two monoclonal antibodies (mAb) within cluster M4 of the myeloid section of the Second International Swine CD Workshop, C4 (No. 144) and PM18-7 (No. 192), showed reactivity with thymocytes and among cells of myelomonocytic origin with mature macrophages but not with monocytes and granulocytes. Both mAb recognize a protein showing two bands of 205 kDa and 130 kDa under both reducing and non-reducing conditions. Although epitope mapping with these mAb could not be performed, this cluster received the SWC9 designation.     

Characterization of volatiles and aroma-active compounds in honeybush (Cyclopia subternata) by GC-MS and GC-O analysis

Volatile organic compounds (VOCs) in fermented honeybush, Cyclopia subternata, were sampled by means of a high-capacity headspace sample enrichment probe (SEP) and analyzed by gas chromatography-mass spectrometry (GC-MS). Stereochemistry was determined by means of enantioselective GC-MS with derivatized β-cyclodextrin columns as chiral selectors. A total of 183 compounds, the majority of which are terpenoids (103; 56%), were identified by comparing their mass spectra and retention indices with those of reference compounds or tentatively identified by comparison with spectral library or literature data. Of these compounds, 37 were determined by gas chromatography-olfactometry (GC-O), using detection frequency (DF) and aroma extract dilution analysis (AEDA), to be odor-active (FD ≥ 2). (E)-β-Damascenone, (R/S)-linalool, (E)-β-damascone, geraniol, (E)-β-ionone, and (7E)-megastigma-5,7,9-trien-4-one were identified with the highest FD factors (≥512). The odors of certain compounds, that is, (6E,8Z)-megastigma-4,6,8-trien-3-one, (6E,8E)-megastigma-4,6,8-trien-3-one, (7E)-megastigma-5,7,9-trien-4-one, 10-epi-γ-eudesmol, epi-α-muurolol, and epi-α-cadinol, were perceived by GC-O assessors as typically honeybush-like.     

Ecological Effects and Biomonitoring for Mercury in Tropical Ecosystems

Considerable attention has been devoted to monitoring heavy metals in temperate zones of the world, largely due to the concentration of industries and populations in these regions. With increases in global transport of mercury, it has become important to examine the effects of mercury on components of tropical ecosystems, and to design biomonitoring schemes to assess environmental changes involving mercury. Tropical ecosystems differ from temperate ones in fundamental ways, including increased species diversity, and decreased niche width, spatial heterogeneity, food web lengths and complexity, productivity and soil laterization. Because of these differences, the fate and transport of mercury may differ in temperate and tropical systems, and it is suggested in this paper that bird feathers be used as a biomonitoring tool to assess broad-scale trends in mercury exposure, as well as being indicative of adverse effects on the birds themselves. In many ecosystems, some species of birds occupy top trophic levels. It is apparent that the mercury level in feathers of some tropical birds are as high as those from temperature regions, exceeding levels associated with adverse effects in laboratory studies.     

Flavor release and perception of flavored whey protein gels: perception is determined by texture rather than by release

Five whey protein gels, with different gel hardnesses and waterholding capacities, were flavored with ethylbutyrate or diacetyl and evaluated by a 10-person panel to study the relation between the gel structure and the sensory perception, as well as the nosespace flavor concentration during eating. The sensory perception of the flavor compounds was measured by the time-intensity method, while simultaneously the nosespace flavor concentration was monitored by the MS-Nose. The nosespace flavor concentration was found to be independent of the gel hardness or waterholding capacity. However, significant changes in flavor intensity between the gels were perceived by the majority of the panelists, despite the fact that the panelists were instructed to focus only on flavor perception and to not take texture into account. From these observations it is concluded that the texture of gels determines perception of flavor intensity rather than the in-nose flavor concentration.     

Fumonisin mycotoxins in traditional Xhosa maize beer in South Africa

The production and consumption of home-brewed Xhosa maize beer is a widespread traditional practice in the former Transkei region of South Africa. HPLC determination of fumonisins B1 (FB1), B2 (FB2), and B3 (FB3) in maize beer samples collected in two magisterial areas, Centane and Bizana, showed a wide range of levels. All samples were positive for FB(1), with a mean level of 281 +/- 262 ng/mL and a range from 38 to 1066 ng/mL. Total fumonisins (FB1 + FB2 + FB3) ranged from 43 to 1329 ng/mL, with a mean of 369 +/- 345 ng/mL. Data on the consumption of home-brewed beer are not available. On the basis of published data for the consumption of commercial beer in South Africa, the fumonisin exposure in these districts among the consumers of maize beer was found to be well above the provisional maximum tolerable daily intake of 2 mug/kg of body weight/day set by the Joint FAO/WHO Expert Committee on Food Additives.     

Effect of emulsion properties on release of esters under static headspace, in vivo, and artificial throat conditions in relation to sensory intensity

The effects of oil content and droplet size distributions of dilute oil-in-water emulsions on release of four esters with different hydrophobicities were studied under in vivo, static headspace, and artificial throat conditions. The effect of oil content on orthonasal and retronasal perceived intensity of ethyl hexanoate was studied using a seven-person panel. With increasing oil content and with a higher hydrophobicity of the aroma compound, a stronger decrease in aroma release was found. This effect was stronger under static headspace conditions than under in vivo and artificial throat conditions, and the sensory intensity of ethyl hexanoate was perceived stronger orthonasally than retronasally. The lowest effective oil content was determined for all systems. Of the compounds tested, droplet size distribution only influenced the in vivo release of geranyl acetate. The artificial throat results correlated well with in vivo release, giving support to the assumption that a thin layer of liquid remaining in the throat after swallowing determines aroma release.