Occurrence and hydrological effects of water repellency in different soil and land use types in Mexican volcanic highlands   总被引：1，自引：0，他引：1  

Antonio Jordn  Lorena M. Zavala  Alejandra L. Nava  Nancy Alanís 《CATENA》2009,79(1):383

Little is known on the hydrological behavior of the volcanic ash soils, which are characterized by extremely high porosities and hydraulic conductivities. In this study the occurrence and hydrological effects of water repellency were investigated at a plot scale for different types of land use and volcanic soils in Mexican volcanic highlands from Michoacan, Mexico: [1] fir, pine and oak mixed forest soils developed from lavas, [2] soils developed from volcanic ashes and pyroclastic sediments under sparse fir, pine and oak forest and shrubland, [3] pine and oak forested soils developed from lavas and pyroclastic sediments, and [4] bare soils on recent ash sediments in plain surfaces. Soil water repellency was assessed using the water drop penetration time test and rainfall simulations were performed on circular plots (50 cm in diameter) during 30 min and at an intensity of 90 mm h^− 1 in order to study the hydrological response of each area. The return period for storms with a similar intensity in the area is 10 years. The shape and depth of the wetting front after simulated rainfall was also analyzed. Soil water repellency showed a high variability among the different studied zones. Organic matter content, soil texture and acidity were the most important factors for developing hydrophobicity. A wide range of soil water repellency classes (hydrophilic to severely water-repellent soils) has been found in soils under dense fir, pine and oak mixed forests or shrubland, while inexistent or slight water repellency has been observed in soils under sparse forest or at bare ash-covered areas. At a plot scale, marked differences in the hydrological behavior of the studied land use and soil zones were observed after the rainfall simulations. Soil water repellency contributes to fast ponding and runoff generation during the first stages of rainstorms. Runoff was enhanced in water-repellent forested soils (average runoff coefficients between 15.7 and 19.9%), in contrast to hydrophilic or slightly water-repellent soils, where runoff rates were lower (between 1.0 and 11.7%). Shallow and irregular wetting fronts were observed at water-repellent zones, reducing the soil water storage capacity. The implications of soil water repellency in soil hydrology and erosion risk in the area shed light on the soil hydrology of the studied ecosystems, and can contribute to develop better management policies.  相似文献   

Seedlings growth promotion by Azospirillum brasilense under normal and drought conditions remains unaltered in Tebuconazole-treated wheat seeds     

M. Alejandra Pereyra  Florencia M. Ballesteros  Cecilia M. Creus  Rolando J. Sueldo  Carlos A. Barassi 《European Journal of Soil Biology》2009,45(1):20-27

The wide use of pesticides in modern agriculture may cause side effects on the non-target microflora. Data on the fungicide Tebuconazole effects on Azospirillum-wheat association are scarce. We analyzed the effects of Tebuconazole on: (a) Azospirillum brasilense Sp245 growth in pure culture, (b) A. brasilense Sp245 colonization of Triticum aestivum cv ProINTA Oasis roots, (c) A. brasilense Sp245-inoculated seedlings growth under normal and water stress conditions in the presence of 20% polyethylene glycol 8000. Seeds were separated in Tebuconazole-free and Tebuconazole-treated lots. Inoculated and non-inoculated seedlings were grown in hydroponics in the dark at 20 °C for 72 h. Root surface, coleoptile length, fresh and dry (DW) weights in both tissues and diazotrophic bacterial most probable number in roots were determined. Water contents and shoot-to-roots DW ratio were calculated. Neither Azospirillum growth nor root colonization was affected by Tebuconazole. Under normal growth conditions most of the growth parameters analyzed, revealed a clear positive effect of A. brasilense on wheat seedlings up to 72 h treatments. The characteristic Azospirillum enhancing effects observed on roots remained unaltered by Tebuconazole. The present study shows that Tebuconazole is compatible with A. brasilense Sp245-wheat inoculation.  相似文献   

Synthesis of oligosaccharides derived from lactulose and pectinex ultra SP-L     

Cardelle-Cobas A  Martínez-Villaluenga C  Villamiel M  Olano A  Corzo N 《Journal of agricultural and food chemistry》2008,56(9):3328-3333

The beta-galactosidase activity of the commercial enzymatic preparation Pectinex Ultra SP-L derived from Aspergillus aculeatus has been used to hydrolyze and transgalactosylate the prebiotic carbohydrate lactulose. During this reaction, new oligosaccharides derived from lactulose have been detected by high-performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD). The presence of the trisaccharide 6'-galactosyl-lactulose, the major compound formed, has been confirmed by NMR. In addition, disaccharides and other oligosaccharides with higher retention times have been also detected. The effect of transgalactosylation conditions such as time, temperature, pH, and initial lactulose and enzyme concentrations, as well as product inhibition on oligosaccharide synthesis, has been studied. The optimal conditions for the formation of tri and higher oligosaccharides were 60 degrees C, pH 6.5, 450 g/L lactulose, 16 units/mL of enzyme, and 7 h of reaction. Selective formation of disaccharides was achieved under the same conditions with the exception of pH (4.5). The present work provides additional knowledge on the synthesis of new oligosaccharides with potential prebiotic properties.  相似文献   

Isomerization of lactose-derived oligosaccharides: a case study using sodium aluminate     

Cardelle-Cobas A  Corzo N  Villamiel M  Olano A 《Journal of agricultural and food chemistry》2008,56(22):10954-10959

Galactooligosaccharides (GOS) obtained during the enzymatic hydrolysis of lactose contain large amounts of glucose, galactose, and unreacted lactose, which do not have prebiotic properties and increase the calorific value of the product. In this work, the isomerization of the GOS mixture by the action of sodium aluminate has been studied. During the reaction, lactose, glucose, and galactose were isomerized to lactulose, fructose, and tagatose, respectively, and in addition allolactose, 6-galactobiose, and 6'-galactosyl-lactose were also converted to the corresponding keto-sugars. The effect of time, temperature, and aluminate/initial lactose ratio has been studied. After 9 h at 40 degrees C and molar ratio aluminate/lactose 3:1, the isomerization yield was >60%, and the amount of final carbohydrates was close to 90% of the initial product. This process considerably decreases the amount of lactose, glucose, and galactose.  相似文献   

Evaluation of formalin-fixed paraffin-embedded tissues from vaccine site-associated sarcomas of cats for papillomavirus DNA and antigen     

Kidney BA  Haines DM  Ellis JA  Burnham ML  Teifke JP  Czerwinski G  Jackson ML 《American journal of veterinary research》2001,62(6):833-839

OBJECTIVE: To determine whether vaccine site-associated sarcomas (VSS) from cats contain papillomavirus antigen or DNA. SAMPLE POPULATION: 50 formalin-fixed paraffin-embedded tissue blocks of VSS from cats. PROCEDURE: Sections from each tissue block were evaluated for papillomavirus antigen by use of an avidin-biotin-complex immunohistochemical staining method, using rabbit anti-bovine papillomavirus type-1 antibody. The DNA was extracted from sections of each tissue block, and polymerase chain reaction assays were performed, using primers designed to amplify regions of the E5 gene of bovine papillomavirus and consensus primers designed to amplify a region of the L1 gene of animal papillomaviruses. Sections from 20 of the tissue blocks were evaluated by use of nonradioactive in situ hybridization for bovine papillomavirus DNA. RESULTS: Papillomavirus antigen and DNA were not detected in any of the VSS. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that papillomaviruses likely do not have any direct involvement in the pathogenesis of VSS in cats.  相似文献   

Ontogenic maturation of the somatotropin/insulin-like growth factor axis     

Harrell RJ  Thomas MJ  Boyd RD  Czerwinski SM  Steele NC  Bauman DE 《Journal of animal science》1999,77(11):2934-2941

The ontogeny of the somatotropin/insulin-like growth factor system was examined in well-fed pigs under basal conditions and during a short-term challenge of porcine ST (pST). The study was conducted with two replicates of eight castrate male pigs from 3.8 kg BW (10 d of age) to 92 kg BW (129 d of age). Pigs were reared individually with ad libitum access to milk replacer through 23 d of age. Thereafter, pigs were fed a corn, soybean meal, and dry skim milk diet formulated to exceed nutrient requirements by approximately 30%. Pigs were randomly assigned to receive daily i.m. injections of either 0 (buffer) or 120 microg/kg BW of pST for a duration of 4 d starting at 10, 19, 33, 43, 63, 83, and 125 d of age. Blood was collected via jugular venipuncture on d 0 and 4 of the challenge. Circulating levels of IGF-I were not dramatically affected by age, but levels of IGF-II were low from 10 to 19 d of age and then increased through later stages of growth. Circulating concentrations of IGF binding protein (BP)-3 increased with age (P < .05), but levels of IGFBP-2, a 30-kDa IGFBP, and IGFBP-4 were unchanged (P > .10). The pST challenge reduced plasma urea nitrogen at all ages, but the magnitude of the response was less in younger pigs compared with the maximum response in pigs greater than 30 kg BW (63 d of age). The IGF-I response to the pST challenge also increased from approximately 30% in young pigs to a threefold increase in older pigs. Regardless of age, concentrations of IGF-II were minimally affected by the pST challenge. Circulating levels of IGFBP-3 increased and IGFBP-2 levels decreased in response to the pST challenge, and the magnitude increased with age. The high nutritional status of pigs in the early phases of growth diminished the postnatal changes in IGF-I and IGFBP-2, but not IGF-II or IGFBP-3. Overall, data demonstrate a developmental regulation of the ST/IGF system, with pST challenges altering circulating concentrations of IGF-I, IGFBP-3, and IGFBP-2 coincident with changes in amino acid metabolism.  相似文献   

Characterization of an Extracellular Serine Protease of Fusarium eumartii and its Action on Pathogenesis Related Proteins     

Florencia Olivieri  María Eugenia Zanetti  Claudia R. Oliva  Alejandra A. Covarrubias  Claudia A. Casalongué 《European journal of plant pathology / European Foundation for Plant Pathology》2002,108(1):63-72

Proteases have been proposed as part of the invasion strategies of some pathogenic fungi. In this work, a serine protease produced by the phytopathogenic fungus Fusarium solani f.sp. eumartii was purified and characterized. Purification of the enzyme was accomplished by gel filtration through a Superose 12 column, followed by hydrophobic interaction chromatography in Phenyl Superose and gel filtration chromatography through Superdex 75. Analysis of the purified enzyme by SDS/PAGE without heat treatment, revealed a single band, which corresponded to the proteolytic activity detected by zymogram. When this protein was subjected to denaturing conditions, two major polypeptides of approximately 30 and 33kDa were revealed. The N-terminal amino acid sequence of one of these polypeptides showed a high similarity with fungal mature serine proteases of the subtilisin family. This protease hydrolysed in vitro, specific polypeptides of potato intercellular washing fluids and cell walls. The protease was also able to degrade pathogenesis-related proteins from the intercellular washing fluids. The role of this serine protease as part of the fungal strategy to colonize potato tuber tissues is discussed.  相似文献   

Dynamic exophthalmos and lateral strabismus in a dog caused by masticatory muscle myositis          下载免费PDF全文

Sarah L. Czerwinski  Caryn E. Plummer  Shari M. Greenberg  William F. Craft  Julia A. Conway  Mayrim L. Perez  Kirsten L. Cooke  Matthew D. Winter 《Veterinary ophthalmology》2015,18(6):515-520

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Retrospective study of the perioperative management and complications of ureteral obstruction in 37 cats          下载免费PDF全文

Alejandra Garcia de Carellan Mateo  David Brodbelt  Nicola Kulendra  Hatim Alibhai 《Veterinary anaesthesia and analgesia》2015,42(6):570-579

ObjectivesTo describe perioperative management and complications, risk factors and mortality rates in cats anaesthetized for treatment of ureteral obstruction.Study designRetrospective, clinical, cohort study.AnimalsThirty-seven client-owned cats anaesthetized for ureteral surgery.MethodsRecords with sufficient data for cats treated between March 2010 and March 2013 were examined for breed, age, gender, history, concurrent diseases, pre- and post-anaesthetic biochemical and haematological parameters, American Society of Anesthesiologists classification, anaesthetic protocol, surgical technique, surgeon, perioperative complications and mortality within 48 hours after extubation. Associations between risk factors and outcome variables were evaluated using univariable analysis. Odds ratios and 95% confidence intervals were calculated for significant parameters. Sensitivity and specificity using receiving operator characteristic curve analysis were calculated for creatinine, potassium level and standard base excess (SBE) to denote survival or non-survival.ResultsPreoperatively, all cats were azotaemic: mean ± SD urea was 31.6 ± 26.9 mmol L⁻¹ and median (range) creatinine was 562 μmol L⁻¹ (95 μmol L⁻¹ to off scale). Thirteen cats were hyperkalaemic (K⁺ > 6.5 mmol L⁻¹). Anaesthesia-related complications included bradycardia (n = 8, 21.6%), hypotension (n = 15, 40.5%) and hypothermia (n = 32, 86.5%). Seven cats (18.9%) died postoperatively. Non-survivors were significantly (p = 0.011) older (9.8 ± 1.9 years) than survivors (6.4 ± 3.1 years) and had higher potassium concentrations (p = 0.040). Risk factors associated with mortality were ASA classes IV and V (p = 0.022), emergency procedures (p = 0.045) and bicarbonate administration (p = 0.002). Non-survivors had higher creatinine concentrations (p = 0.021) and lower SBE (p = 0.030).Conclusion and clinical relevanceIntraoperative anaesthetic complications were common; increased age, poor health status, preoperative bicarbonate administration, hyperkalaemia and increased creatinine were associated with increased risk for death and can be used to predict risk for complications.  相似文献   

Resistance to <Emphasis Type="Italic">Penicillium</Emphasis><Emphasis Type="Italic">hirsutum</Emphasis> Dierckx in garlic accessions     

Pablo?F.?CavagnaroEmail author  Alejandra?Camargo  Ricardo?J.?Piccolo  Sandra?García?Lampasona  Jose?L.?Burba  Ricardo?W.?Masuelli 《European journal of plant pathology / European Foundation for Plant Pathology》2005,112(2):195-199

Among the factors affecting the quality and yield of garlic production, blue mold caused by -- Penicillium spp. -- is responsible for economical losses in many countries. Allicin, present in garlic bulbs, has been suggested as having antifungal activity against some Penicillium species. This study was conducted to evaluate the response of garlic accessions against Penicillium hirsutum infection and to compare this response with bulb allicin content. Twelve garlic accessions were inoculated with P. hirsutum, and assayed in greenhouse and growth chamber experiments. Plant growth parameters and the fungal production of conidia were evaluated. Significant differences were found among the accessions. Accessions Castaño and Morado were most resistant whereas AR-I-125 and Fuego were always severely affected by the disease. A low correlation was found (r = 0.17) between allicin content and tolerance, indicating that allicin is not the main factor involved in the resistance against P. hirsutum.  相似文献