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排序方式: 共有115条查询结果,搜索用时 15 毫秒
1.
The objective of this study was to investigate the structural changes of whey proteins during exposure in a continuous-flow UV reactor. Varying UV irradiation dosages were obtained by controlling the flow rate and the mixing speed. Whey protein isolate (WPI) solutions at concentrations of 1% and 5% (w/v) were circulated at flow rates ranging from 30 to 800 mL·min(-1), and changes in physicochemical properties of the proteins were investigated. Intrinsic fluorescence spectra and surface hydrophobicity measurements suggested changes in the tertiary structure of the proteins with UV exposure. The UV treatment also increased the concentration of total and accessible thiol groups in 1% WPI solutions, while no change was measured in 5% WPI solutions. Size-exclusion chromatography demonstrated the formation of UV-induced aggregates and oxidation products (N-formylkynurenine and dityrosine) of aromatic amino acids. Furthermore, the UV-induced changes in protein conformation increased the susceptibility of whey proteins to pepsin hydrolysis. 相似文献
2.
B Horvat T Willhaus H R Frey B Liess 《Zentralblatt für Veterin?rmedizin. Reihe B. Journal of veterinary medicine. Series B》1989,36(9):715-718
In the Norddeich orphanage seals about four to five months of age were exposed intranasally and by contact to a phocine herpesvirus which originated from a young seal in this station. Virus excretion by the nasal route was observed in two animals on day 2 and 15 post inoculation, respectively. Production of neutralizing antibodies was detected one week after exposure. The antibody titre range was approximately tenfold higher in the inoculated seals than in animals of the contact group. The seals did not become seriously sick. 相似文献
3.
Liu J Verespej E Alexander M Corredig M 《Journal of agricultural and food chemistry》2007,55(15):6270-6278
The interactions of high-methoxyl pectin (HMP) and soybean-soluble polysaccharide (SSPS) with sodium caseinate-stabilized emulsions were investigated using a multitechnique approach, including dynamic light scattering (DLS), electrophoretic mobility measurements, transmission diffusing wave spectroscopy (DWS), and ultrasonic spectroscopy (US). At pH 6.8, both polysaccharides are negatively charged and did not adsorb onto caseinate-coated droplets due to electrostatic repulsion; however, SSPS showed a different behavior compared to HMP in the turbidity parameter 1/l* and sound attenuation parameters measured by DWS and US, respectively. The present study brought the first evidence of the stabilization effect of SSPS in acidified sodium caseinate-emulsions. While destabilization occurred at low polysaccharide concentrations, probably via bridging flocculation, acid-induced aggregation of the oil droplet was completely prevented by 0.2% SSPS or HMP. However, the interaction behavior of SSPS during acidification was different from that of HMP. This was demonstrated by the different development of the parameter 1/l*, droplet sizes, sound attenuation, and velocity. 相似文献
4.
Milena Fernandes Michael Angove Talya Sedawie & Anthony Cheshire 《Aquaculture Research》2007,38(4):388-397
Finfish pens are point sources of dissolved nutrients released from fish metabolism or degradation of solid wastes. Nutrients leaching from uneaten feed and faeces are not usually quantified in mass budgets for these systems, leading to an overestimation of fish retention or deposition to the seabed. In this study, we investigated nutrient leaching from pellets and baitfish feed as well as faeces of southern bluefin tuna (Thunnus maccoyii) into seawater. Faeces were nitrogen depleted (51–54 mg N g−1 dw) and phosphorus enriched (62–72 mg P g−1 dw) compared with feeds (83–111 mg N g−1 dw and 17–21 mg P g−1 dw). Less phosphorus was available for leaching from pellets and faeces of pellet‐fed tuna (5–6%) than from baitfish and faeces of baitfish‐fed tuna (17–21%). The proportion of soluble nitrogen in pellets (15%) was also lower than in baitfish and faeces (35–43%). Leaching loads for a feed conversion ratio of 5 were estimated as 22 and 26 kg N tonne−1 growth when baitfish or pellets were used as feed respectively. Phosphorus loads were estimated as 15 and 4 kg P tonne−1 growth respectively. More than 90% of nitrogen loads, and approximately 50% of phosphorus, are likely to be released into seawater before solid wastes reach the seafloor. 相似文献
5.
Milena Bordignon Laura Da Dalt Lieta Marinelli Gianfranco Gabai 《Veterinary journal (London, England : 1997)》2014,199(1):162-168
Despite the recognised importance of oxidative stress in the health and immune function of dairy cows, protein oxidation markers have been poorly studied in this species. The current study aimed to characterise markers of protein oxidation generated by activated bovine neutrophils and investigate the biological effects of advanced oxidation protein products (AOPP) on bovine neutrophils. Markers of protein oxidation (AOPP, dityrosines and carbonyls) were measured in culture medium containing bovine serum albumin (BSA) exposed to neutrophils. The effect of AOPP-BSA on generation of reactive oxygen species (ROS) was assessed by chemiluminescence. Activation of caspases-3, -8 and -9 and the presence of DNA laddering were used as apoptosis markers.Greater amounts of AOPP were generated by phorbol myristate acetate (PMA)-activated than non-activated neutrophils (1.46 ± 0.13 vs. 0.75 ± 0.13 nmol/mg protein, respectively; P < 0.05). Activated neutrophils and hypochlorous acid generated slightly different patterns of oxidized protein markers. Exposure to AOPP-BSA did not stimulate ROS production. Activated neutrophils generated a lesser amount of ROS when incubated with AOPP-BSA (P < 0.001). Activation with PMA induced a loss of viable neutrophils after 3 h, which was greater with AOPP-BSA incubation (P < 0.05). Detectable amounts of active caspases-3, -8 and -9 were found in nearly all samples but differences in caspase activation or DNA laddering were not observed comparing treatment groups. Apoptosis was unlikely to be responsible for the greater loss of PMA-activated neutrophils cultured in AOPP-BSA and it is possible that primary necrosis occurred. The results suggest that accumulation of oxidized proteins at an inflammatory site might result in a progressive reduction of neutrophil viability. 相似文献
6.
Development and application of functional markers in maize 总被引:8,自引:0,他引:8
Thomas Lübberstedt Imad Zein Jeppe Reitan Andersen Gerhard Wenzel Birte Krützfeldt Joachim Eder Milena Ouzunova Shi Chun 《Euphytica》2005,146(1-2):101-108
Summary Functional markers (FMs) are derived from polymorphic sites within genes causally involved in phenotypic trait variation (Andersen,
J.R. & T. Lübberstedt, 2003. Trends Plant Sci 8: 554–560). FM development requires allele sequences of functionally characterized
genes from which polymorphic, functional motifs affecting plant phenotype can be identified. In maize and other species with
low levels of linkage disequilibrium, association studies have the potential to identify sequence motifs, such as a few nucleotides
or insertions/deletions, affecting trait expression. In one of the pioneering studies, nine sequence motifs in the dwarf8 gene of maize were shown to be associated with variation for flowering time (Thornsberry, J.M., M.M. Goodman, J. Doebley,
S. Kresovich, D. Nielsen & E.S. Buckler, 2001. Nat Genet 28: 286–289). Proof of sequence motif function can be obtained by
comparing isogenic genotypes differing in single sequence motifs. At current, the most appropriate approach for this purpose
in crops is targeting induced local lesions in genomes (TILLING) (McCallum, C.M., L. Comai, E.A. Greene & S. Henikoff, 2000.
Nat Biotechnol 18: 455–457). In central Europe, maize is mainly grown as forage crop, with forage quality as major trait,
which can be determined as proportion of digestible neutral detergent fiber (DNDF). Brown midrib gene knock out mutations have been shown to be beneficial for forage quality but disadvantageous for overall agronomic performance.
Two brown midrib genes (bm1 and bm3) have been shown to be involved in monolignol biosynthesis. These two and additional lignin biosynthesis genes have been
isolated based on sequence homology. Additional candidate genes putatively affecting forage quality have been identified by
expression profiling using, e.g., isogenic bm lines. Furthermore, we identified an association between a polymorphism at the COMT locus and DNDF in a collection of European
elite inbred lines. 相似文献
7.
The aim of this research was to validate the results obtained previously by purge and trap (PT) and to investigate the ability of solid phase microextraction (SPME), a more rapid and less expensive technique, to discriminate drinking milk subjected to different heat treatments (i.e., pasteurization, ultrahigh temperature, "in-bottle" sterilization) and produced at different factories. The data obtained by both methods were processed by multivariate statistical analysis. PT and SPME showed comparable repeatability, although with different performances for the yield of extraction, and allowed the three milk categories to be distinguished. Within the chemical class of methyl ketones, 2-heptanone was found to be the most discriminating compound, and the possibility of using the concentration of this volatile as a marker for heat treatment was investigated. 相似文献
8.
Paul Van de Wouw Cristian EcheverríaJosé María Rey-Benayas Milena Holmgren 《Forest Ecology and Management》2011,262(6):1100-1108
Mediterranean ecosystems are global hotspots of biodiversity threaten by human disturbances. Growing evidence indicates that regeneration of Mediterranean forests can be halted under certain circumstances and that successional stages can become notoriously persistent. The Mediterranean sclerophyllous forest in central Chile is been largely transformed into savannas dominated by the invasive legume tree Acacia caven as result of interacting management and ecological factors. We used multi-temporal satellite imagery to study the transition dynamics of these major vegetation types over the last four decades (1975-2008). Vegetation changes were related to indicators of resource availability (topography, water availability, solar radiance), potential propagule availability (distance to forest remnant patches) and disturbance regimes (grazing, fire occurrence and distance to roads and cities). During this study period, forests were mostly converted into Acacia savannas (46.1%). Acacia savanna was the most persistent natural vegetation type. The probability of sclerophyllous forest degradation into Acacia savanna increased on drier northern-exposed slopes, close to roads and further away from forest remnants. In contrast, forest regeneration from Acacia savanna was higher on moister southern-exposed slopes and closer to forest remnants. Acacia savannas are increasingly being converted into cultivated land on the moister locations or switching into a bare soil state in locations close to cities and further away from forest remnants. These results highlight the vulnerability of diverse sclerophyllous forests and its increasing conversion into persistent Acacia savannas in the Mediterranean region of central Chile and identify the ecological conditions for successful conservation and restoration of the native sclerophyllous forest vegetation that can be used for sensible land use planning. 相似文献
9.
Bogumił Rychcik Jadwiga Wierzbowska Milena Kaźmierczak-Pietkiewicz Arkadiusz Światły 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2020,70(4):349-359
ABSTRACTThe content of macronutrients in potato tubers arouses interest because of their substantial consumption in the world and significant role in elements' budget in human diet. The research objective has been to evaluate the content of macronutrients in tubers of potatoes grown in different systems of crop production in Poland. In 2012–2014, an experiment was conducted to test potato cultivation in three-crop production systems: conventional, integrated and organic. In each of the six-field crop rotation systems, there were five potato cultivars classified into different earliness groups. The following macronutrients in dry mass of potato tubers were determined: N, P, K, Ca, Mg, Na, S and Cl, and the various ratios between them were calculated. The research carried out proved that potatoes production systems affect the chemical composition of tubers, which is additionally modified by whether condition and genetic features of cultivars. Potato tubers from organic farming contained by about 20% less N than tubers from conventional or integrated systems. Potato tubers from organic production system displayed lower content of Ca and Na in comparison with the conventional and integrated systems. The least of P and S were detected in tubers of the potatoes grown conventionally. 相似文献
10.
Beatriz Wiebke-Strohm Annette Droste Giancarlo Pasquali Marina Borges Osorio Lauro Bücker-Neto Luciane Maria Pereira Passaglia Marta Bencke Milena Schenkel Homrich Márcia Margis-Pinheiro Maria Helena Bodanese-Zanettini 《Euphytica》2011,177(3):343-354
An Agrobacterium-mediated transformation procedure for soybean [Glycine max L. Merrill] proliferating somatic embryos is here described. The Agrobacterium tumefaciens LBA4404 strain harboring pTOK233, pCAMBIA1390-olp or pH7WG2Dwrky plasmids was used to mediate gene transfer into the plant genome. Prior to Agrobacterium inoculation, proliferative soybean embryogenic clusters were microwounded by DNA-free tungsten particle bombardment. Three
independent transformation experiments were performed. In Experiment I, 26 transgenic plants were obtained from a unique clone
of cv Bragg, while 580 plants were recovered from 105 clones of cv IAS5. In Experiment II, a single hygromycin-resistant clone
of cv BRSMG68 Vencedora was recovered and gave rise to five plants. In Experiment III, 19 plants of cv Bragg and 48 plants
of IAS5 were recovered, representing five and 14 independent transformation events, respectively. PCR and Southern analyses
confirmed the transgenes’ integration into plant genomes. Transgenic plants were fertile. They flowered, set pods and seeds.
Transgene segregation in two T1 progenies fits the Mendelian pattern (3:1 transgenic:non-transgenic plants). This is the first report of transgenic fertile
soybean plants obtained from somatic embryogenic tissues transformed by the system that combines DNA-free particle bombardment
and Agrobacterium. 相似文献