Direct determination of paclobutrazol residues in pear samples by liquid chromatography-electrospray tandem mass spectrometry     

Sancho JV  Pozo OJ  Zamora T  Grimalt S  Hernández F 《Journal of agricultural and food chemistry》2003,51(15):4202-4206

A rapid and sensitive liquid chromatography/electrospray ionization/tandem mass spectrometry (LC-ESI-MS-MS) method has been developed for the determination of the plant growth regulator paclobutrazol in pear samples. Extraction was performed with methanol by using a high-speed blender Ultra-Turrax, and 10 microL of pear extract was directly injected in the LC-ESI-MS-MS system without any previous sample treatment. The highest sensitivity of the method was achieved under MS-MS conditions obtaining a limit of detection of 0.7 microg/kg and a quantification limit of 5 microg/kg, with a run time of only 5.5 min. Recoveries for paclobutrazol from spiked pear samples at 0.005, 0.05, and 0.5 mg/kg were around 82-102% with relative standard deviations between 2 and 7%. The method was applied to real treated and untreated samples of pears, using quality control samples as a evaluation of the method reliability. Two MS-MS transitions were selected, one for quantification (294 > 70) and the other for confirmation of the analyte (296 > 70). All the experiments were performed in compliance with good laboratory practices.  相似文献   

Low genetic diversity threatens imminent extinction for the Hungarian meadow viper (Vipera ursinii rakosiensis)     

Beáta Újvári  Thomas Madsen  Tatiana KotenkoMats Olsson  Richard ShineHåkan Wittzell 《Biological conservation》2002,105(1):127-130

Meadow vipers (Vipera ursinii) are small venomous snakes whose range in Hungary has been greatly fragmented by anthropogenic habitat disturbance (especially, agriculture). We obtained DNA from a total of eight Hungarian snakes. Genetic variability at the major histocompatibility (Mhc) class I loci was much lower for these snakes than for specimens from two large Ukrainian populations. Within two Hungarian populations for which we had multiple individuals, band-sharing indices were 100 and 84.6% (versus 63.3 and 57% for the Ukraine populations). The Ukrainian snakes also displayed more RFLP fragments than the Hungarian vipers (mean 13.7 versus 9.0, respectively). In combination with reports of birth deformities, chromosomal abnormalities and low juvenile survival, these data strongly suggest that the Hungarian vipers are experiencing inbreeding depression. Genetic diversity is still present in the Hungarian vipers but among rather than within populations. Given the very low numbers of animals, the only feasible strategy to increase the genetic diversity and to save the Hungarian vipers from extinction is to implement a captive breeding program based on genetically screened animals.  相似文献   

Intragenic vectors for gene transfer without foreign DNA     

Anthony J. Conner  Philippa J. Barrell  Samantha J. Baldwin  Annemarie S. Lokerse  Pauline A. Cooper  Astrid K. Erasmuson  Jan-Peter Nap  Jeanne M. E. Jacobs 《Euphytica》2007,154(3):341-353

The intragenic vector system involves identifying functional equivalents of vector components from the genome of a specific crop species (or related species to which it can be hybridised) and using these DNA sequences to assemble vectors for transformation of that plant species. This system offers an attractive alternative to current genetic engineering strategies where vectors are based on DNA sequences that usually originate from bacteria. The construction of intragenic vectors enables the well-defined genetic improvement of plants with all transferred DNA originating from within the gene pool already available to plant breeders. In this manner genes can be introgressed into elite cultivars in a single step without linkage drag and without the incorporation of foreign DNA. The resulting plants are non-transgenic, although they are derived using the tools of molecular biology and plant transformation. The use of intragenic vectors for the transfer of genes from within the gene pools of crops may help to alleviate some of the major public concerns over the deployment of GM crops in agriculture, notably the ethical issue associated with the transfer of DNA across wide taxonomic boundaries. This paper reviews the progress toward the development and use of intragenic vectors and the implications of their use for the genetic improvement of crops. Dedicated to the late Hans Sandbrink for his enthusiasm in helping to develop intragenic vectors  相似文献   

Protected areas and frugivorous fish in tropical rivers: Small-scale fisheries,conservation and ecosystem services     

Paula Nagl  Gustavo Hallwass  Luís H. Tomazoni-Silva  Pedro P. Nitschke  Anais R. P. Rowedder  Astrid Tatiana Romero-Martinez  Renato A. M. Silvano 《水产资源保护:海洋与淡水生态系统》2021,31(10):2752-2771

1. Frugivorous fish provide often conflicting ecosystem services of seed dispersal and food provisioning in tropical rivers. Fishing may reduce the size and abundance of frugivorous fish, thus affecting their potential as seed dispersers, which could affect the conservation of these fish and of floodplain forests.
2. The goal of this study was to assess the influence of co-managed protected areas in the form of extractive reserves (RESEX) and small-scale fisheries on frugivorous fish in the Tapajós and Negro rivers, in the Brazilian Amazon. The study examined whether: (i) frugivorous fish are important for fisheries and selectively caught; and (ii) frugivorous fish abundance, size and fisheries catch per unit of effort are higher inside the RESEX than outside.
3. The analyses included fisheries-dependent data (3,753 fish landings) and independent data (12,730 sampled fish) collected in 16 fishing communities (eight for each river). In both rivers, frugivorous fish are among the 10 species caught the most and frugivorous biomass was proportionately higher in landings than in samplings, indicating fisheries selectivity towards these fishes.
4. In both rivers, catches of frugivorous fish were higher outside the RESEX than inside. Catch per unit effort and the proportion of frugivores in the catch were higher outside the RESEX in the Tapajós River but did not vary between sites inside and outside the RESEX in the Negro River. Frugivorous fish were larger inside the RESEX in the Negro, but smaller inside the RESEX in the Tapajós.
5. The results indicated that the ecosystem services of seed dispersal and food source provided by frugivorous fish are not in conflict in the tropical rivers studied. Therefore, these clearwater and blackwater rivers in the Brazilian Amazon show a balance between fisheries and conservation of frugivorous fish, which play an essential role in the functioning of tropical floodplain forest ecosystems.

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Self-inhibition of spore germination via reactive oxygen in the fungus Cladosporium cucumerinum, causal agent of cucurbit scab     

Andrey A. Aver��yanov  Vera P. Lapikova  Tatiana D. Pasechnik  Tatiana S. Zakharenkova  Con Jacyn Baker 《European journal of plant pathology / European Foundation for Plant Pathology》2011,130(4):541-550

Cladosporium cucumerinum spore germination in vitro depended on spore suspension density. Different fungal isolates displayed germination maxima at different spore concentrations. For one isolate, the maximum was observed at the same spore density at both 18 and 25°C, although germination percentage increased slightly at the higher temperature. Diffusates originating in other spore suspensions of the same isolate reduced germination percentage of spores taken at optimal concentration. The least effect occurred in diffusate taken from spores kept at their optimal concentration. Self-suppression of spore germination at unfavourable concentrations was diminished more or less by antioxidants (superoxide dismutase, catalase, mannitol or formate). The same compounds, added to spore diffusates, reduced their fungitoxicities. All diffusates generated superoxide radical (assayed by adrenalin oxidation sensitive to superoxide dismutase). This activity correlated positively with diffusate toxicity. Leaf inoculation of the susceptible cucumber cultivar at 18°C with spore suspensions at extreme densities, at which they germinated poorly in vitro, led to less disease severity then that at optimal density. In contrast, no disease symptoms appeared at 25°C. It is suggested that spores germinating at their extreme concentrations produced reactive oxygen species, suppressing the pathogen; this effect could reduce disease development at low temperatures. At high temperatures, however, this mechanism seems not to work, suggesting that plant infection may be reduced by other disease inhibiting factors.  相似文献   

Accurate determination of oosporein in fungal culture broth by differential pulse polarography     

Michelitsch A  Rückert U  Rittmannsberger A  Seger C  Strasser H  Likussar W 《Journal of agricultural and food chemistry》2004,52(6):1423-1426

A simple and accurate differential pulse polarographic method has been developed for the determination of oosporein in the culture broth of the fungus Beauveria brongniartii. This hydroxybenzoquinone derivative is the only major secondary metabolite secreted by this entomopathogenic fungus, which is used as biological pest control agent (BCA) against Melolontha melolontha larvae. It can be found in the host organism as well as in the formulated product. The polarographic behavior of oosporein was examined in various buffer systems over the pH range 3-10. In Britton-Robinson buffer/methanol solution (3:7 v/v, pH 5.5) the differential pulse polarograms exhibited reproducible peaks at E(p) = -0.18 V vs silver/silver chloride/potassium chloride (3 M). Under these conditions, a plot of peak height vs concentration of oosporein was found to be linear over the range 5.9 x 10(-)(7) to 2.5 x 10(-)(5) M (0.18-7.74 microg mL(-)(1); r = 0.9998). The detection limit was calculated to be 54 ng mL(-)(1). To evaluate the concentration of oosporein, the standard addition method was applied. The analysis of oosporein in the culture broth led to a mean value of 524.9 microg mL(-)(1) broth with a relative standard deviation (S(rel)) of +/-2.6%. The proposed polarographic method is accurate, not time-consuming, and it is of low cost because no separation steps are necessary.  相似文献   

In Vitro Elution and Antibacterial Activity of Clindamycin,Amikacin, and Vancomycin from R‐gel Polymer     

Leslie A. Thomas DVM  Tatiana Bizikova MSc  Anne C. Minihan DVM  Diplomate ACVS 《Veterinary surgery : VS》2011,40(6):774-780

Objective: To characterize the in vitro elution and bioactivity of 2 formulations of antibiotics in a novel, dissolvable, cross‐linked dextran polymer matrix: Formulation 1—amikacin and clindamycin (AC); Formulation 2—amikacin, clindamycin, and vancomycin (ACV). Study Design: Prospective, in vitro, experimental study. Methods: Aliquots of the antibiotic impregnated polymer were incubated in PBS buffer for 10 days. PBS was changed every 24 hours and concentrations of the antibiotics eluted into saline were quantified. Antimicrobial activity of the eluent from each sampling period was tested for growth inhibition of Staphylococcus aureus. Results: Both formulations of R‐gel^? had a rapid initial release of antibiotics within the first 24 hours and then the concentrations decreased gradually over 10 days. The concentration of amikacin, clindamycin, and vancomycin remained above the breakpoint minimum inhibitory concentration of each drug for a minimum of 9 days. No significant difference (P=.9938, P=.9843) was present in the elution pattern or total amount of antibiotic eluted from clindamycin or amikacin, respectively. Eluent from both groups demonstrated bioactivity against S. aureus for the entire 10‐day study period. Conclusions: Amikacin and clindamycin together, or in combination with vancomycin, elute from R‐gel^? effectively and at gradually decreasing concentrations for at least 10 days. The antibiotics maintained their bioactivity following polymerization and elution from the R‐gel^?.  相似文献   

Fast determination of Sudan dyes in chilli tomato sauces using partial filling micellar electrokinetic chromatography     

Fukuji TS  Castro-Puyana M  Tavares MF  Cifuentes A 《Journal of agricultural and food chemistry》2011,59(22):11903-11909

A new method based on partial filling micellar electrokinetic chromatography (MEKC) for the quantitative determination of Sudan dyes (I, II, III, and IV) in chilli sauces is presented. The separation is achieved filling 25% of the capillary with a MEKC buffer composed of 40 mM NH(4)HCO(3), 25 mM sodium dodecyl sulfate, and 32.5% (v/v) acetonitrile (ACN). The rest of the capillary is filled using a capillary zone electrophoresis (CZE) buffer composed of 40 mM NH(4)HCO(3) and 32.5% (v/v) ACN. Under optimized conditions, the azo dyes are baseline separated in less than 8 min with limits of detection ranging from 0.57 to 0.71 μg mL(-1) (S/N > 3). Using an internal standard, the repeatability of the quantitative determination is improved almost four times. The applicability of the method for rapid screening and determination of Sudan dyes is corroborated by analyzing spiked chilli sauce samples with recoveries from 85 to 99%. The reported conditions are demonstrated to be compatible with mass spectrometry detection.  相似文献   

What is your diagnosis? Fluid aspirated from an abdominal mass in a dog          下载免费PDF全文

Astrid Oscos‐Snowball  Emmeline Tan  Andrew S. Peregrine  Robert Foster  Jessika Bronsoiler  Bruno Gottstein  Emily Jenkins  Karen Gesy  Dorothee Bienzle 《Veterinary clinical pathology / American Society for Veterinary Clinical Pathology》2015,44(1):167-168

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Selection for high and low oxygen consumption altered hepatic mitochondrial energy efficiency in mice          下载免费PDF全文

Yu Hong  Astrid Ardiyanti  Motoi Kikusato  Tomoyuki Shimazu  Masaaki Toyomizu  Keiichi Suzuki 《Animal Science Journal》2015,86(9):818-825

Selection for high (H) and low (L) oxygen consumption (OC) as an indirect estimation of maintenance energy requirement was determined. Feed intake and body weight were measured and feed conversion ratio (FCR) of 4–8‐week‐old mice was calculated. Respiratory activity of hepatic mitochondria was measured at 12 weeks. Total feed intake (H: 103.74 g, L: 97.92 g, P < 0.01), daily feed intake (H: 3.70 g/day, L: 3.50 g/day, P < 0.01) and FCR (H: 18.79, L: 15.50, P < 0.01) were significantly different between lines. The line by sex interaction was significant for FCR. No line differences were observed in males; and the FCR of the H line was greater than in the L line in females. H line mice had the highest hepatic mitochondrial respiratory activity in state 2 (P < 0.01), the highest uncoupled respiratory rate of mitochondria in the presence of an uncoupling agent (P < 0.001), and the mitochondrial proton leak. The adenosine diphosphate/ O ratio was highest in the L line (P < 0.05). This suggests that the selection for high and low OC induced differences in basal mitochondrial respiration and basal metabolism, resulting in difference in FCR between H and L lines.  相似文献