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101.
Landuse can alter soil organic carbon (SOC) fractions by affecting carbon inflows and outflows. This study evaluated changes in SOC fractions in response to different landuses under variable rainfalls. We compared cropland, grassland and forest soils in high rainfall (Islamabad ~1142 mm) and low rainfall (Chakwal ~667 mm) areas of Pothwar dryland, Pakistan. Forest soils in both rainfall areas had highest SOC (11.32 g kg?1), particulate organic carbon (POC, 1.70 g kg?1), mineral-associated organic carbon (MOC, 7.17 g kg?1) and aggregate-associated organic carbon (AOC, 7.86 g kg?1). However, in rangeland and cropland soils, these varied with rainfall. Under high rainfall, SOC and MOC were 12% and 17% higher in rangeland than in cropland while POC and AOC were equal. Under low rainfall, SOC and MOC were higher in rangeland than in cropland by 7.21 and 1.79 g kg?1 at 0–15 cm and equal at 15–30 cm depth. POC and AOC were higher in rangeland than in cropland, in both depths. Averagely, SOC, POC, MOC and AOC were 26%, 68%, 76% and 30% higher in high rainfall than in low rainfall soils. Sensitivity of SOC fractions to landuses observed under different rainfalls could provide useful information for soil management in subtropical drylands. 相似文献
102.
Sara Peres M. Clara F. Magalhães Maria Manuela Abreu Sara Leitão Ana Santos Maria José Cerejeira 《Journal of Soils and Sediments》2016,16(5):1612-1624
Purpose
Wastes from a former Portuguese steel plant were deposited between 1961 and 2001 on the riverbank of a tributary of the Tagus River creating a landfill connected to the river, posing a potential contamination risk to the Tagus estuary ecosystem. This study aims to assess the transfer of chemical elements from contaminated sediments to the estuarine water from cycles of sediment leaching so as to evaluate the ecotoxicity of the leachates, and to analyze the solid phases crystallized from those leachates.Materials and methods
Landfill sediment and estuarine water samples were collected during low tide. Sediment samples were analyzed for pH, electric conductivity (EC), Corg, NPK, and iron oxides. Leaching assays (four replicates) were done using estuarine water (200 cm3/replicate) and 1.5 kg of sediment per reactor. Each reactor was submitted to four leaching processes (0, 28, 49, and 77 days). The sediment was kept moist between leaching processes. Sediment (total (acid digestion) and available fraction (diluted organic acid extraction-Rhizo)) elemental concentrations were determined by inductively coupled plasma–instrumental neutron activation analysis (ICP/INAA). Leachates, and estuarine and sediment pore waters were analyzed for metals/metalloids by ICP/mass spectrometry (MS) and carbonates/sulfate/chloride by standard methodologies. Ecotoxicity assays were performed in leachates and estuarine and pore waters using Artemia franciscana and Brachionus plicatillis. Aliquots of the leachates were evaporated to complete dryness (23–25 °C) and crystals analyzed by X-ray powder diffraction (XRD).Results and discussion
Sediment with pH?=?8 and high EC and Corg was contaminated with As, Cd, Cr, Cu, Pb, and Zn. The element concentrations in the available fraction of the sediment were low compared to the sediment total concentrations (<1 % for Rhizo extraction). The concentrations of potentially hazardous elements in the estuarine water were relatively low, except for Cd. Concentrations of hazardous elements in the leachates were very low. Calcium, K, Mg, Na, and chloride concentrations were high but did not vary significantly among the four leaching experiments. Total concentrations of carbonate were much higher in leachates than in estuarine water. Both estuarine water and leachates showed negligible toxicity. Crystals identified in the solids obtained from the leachates by evaporation were halite, anhydrite, epsomite, dolomite, and polyhalite.Conclusions
The sediment showed the capacity to retain the majority of the potentially hazardous chemical elements. Remobilization of chemical elements from sediment by leaching was essentially negligible. The variation of total concentrations of Ca, carbonate, and sulfate in leachates indicates that the sediment contained reactive sulfides. Due to its composition, the sediment seems to be a dynamic system of pollution control, which should not be disturbed.103.
Hiskett EK Suwitheechon OU Lindbloom-Hawley S Boyle DL Schermerhorn T 《Veterinary research communications》2009,33(3):227-240
In most mammals, glucokinase (GK) acts as a hepatic “glucose sensor” that permits hepatic metabolism to respond appropriately
to changes in plasma glucose concentrations. GK activity is potently regulated by the glucokinase regulatory protein (GKRP),
which is encoded by the GCKR gene. GKRP binds GK in the nucleus and inhibits its activity. GK becomes active when it is released from GKRP and translocates
to the cytosol. Low glucokinase (GK) activity is reported to be a principal feature of feline hepatic carbohydrate metabolism
but the molecular pathways that regulate GK activity are not known. This study examined the hypothesis that species-specific
differences in GKRP expression parallel the low GK activity observed in feline liver. Hepatic GKRP expression was examined
using RT-PCR, immunoblot, and confocal immunomicroscopy. The results show that the GCKR gene is present in the feline genome but GCKR mRNA and the GKRP protein were absent in feline liver. The lack of GKRP expression in feline liver indicates that the low
GK activity cannot be the result of GKRP-mediated inhibition of the GK enzyme. However, the absence of the permissive effects
of GCKR expression on GK expression and activity may contribute to reduced GK enzyme activity in feline liver. The study results
show that the cat is a natural model for GCKR knockout and may be useful to study regulation of GCKR expression and its role in hepatic glucose-sensing and carbohydrate metabolism. 相似文献
104.
Insa S Besalú E Iglesias C Salvadó V Anticó E 《Journal of agricultural and food chemistry》2006,54(3):627-632
The appearance of 2,4,6-trichloroanisole (TCA) in cork stoppers is of great concern because it can cause off-flavors in bottled wine. To prevent this sensorial defect, there should not be any traces of 2,4,6-trichlorophenol (TCP), 2,3,4,6-tetrachlorophenol (TeCP), or pentachlorophenol (PCP) in the finished corks, because they are the direct precursors of TCA. In the course of this study two methodologies based upon an extraction with ethanol/water mixtures to determine the chlorophenolic content in cork matrices were developed. The cork extract is preconcentrated using both solid-phase extraction and solid-phase microextraction methodologies. The latter was optimized by applying a full two-level factorial design. Finally, spiked ground corks at nanogram per gram levels of each chlorophenol were analyzed under optimal conditions and by applying both procedures. The obtained results demonstrate that chlorophenols can be detected in corks contaminated at the nanogram per gram level and, thus, these approaches can be successfully applied as quality control measures in the cork industry. 相似文献
105.
Nguyen D. Kien Tran H. Quang Gunnar Jansson Chris Harwood David Clapham Sara von Arnold 《Annals of Forest Science》2009,66(7):711-711
106.
Sara Mola Ali Abasiyan Hassan Towfighi 《Communications in Soil Science and Plant Analysis》2018,49(6):675-688
Potassium (K+) and nitrogen [N, as the form of ammonium (NH4+)] are major nutrients for plant growth. Although there have been a number of studies on the kinetic fixation of potassium and ammonium ions in soils and clays, however, investigations on the kinetics of competitive fixation of these ions have been few, if any, especially by taking into account silt component of the soils. In this study, the kinetics of potassium and ammonium fixation were examined in the silt components of several soil samples. The results revealed that considerable amounts of K+ and in lesser amounts, NH4+ ions were fixed by silt components of the soils. Potassium fixation was strongly preferred over ammonium. To describe the fixation kinetics, seven mathematically models were evaluated. A comparison of the models showed that pseudo-second-order equation properly described the fixation of these ions by the silt components. 相似文献
107.
Sara Yavari Amirhossein Malakahmad Nasiman B. Sapari Saba Yavari 《Journal of plant nutrition》2018,41(5):545-551
As a green technique, plant-based remediation systems can be used to remove nitrogen (N) pollutants from N-rich wastewaters. However, the excess amount of N and shortage of other nutrients in this system limits the plant growth and affects the plant remediation efficiency. In this study, the effect of adding phosphorus (P) and potassium (K) to the N-enriched wastewater on growth and N-removal efficiency of teak seedlings (Tectona grandis) was evaluated. Twelve ratios of N:P:K were applied to teak seedlings and the related effects were compared with those in control solution containing only N. The results indicated that a ratio of 1N:0.5P:1K increased dry matter accumulation in teak seedlings by improving the balance of nutrients in plants. Teak seedlings grown in nutritionally-improved system eliminated 33.8% N more than those grown in only N solution. The water loss through plant uptake was also enhanced in the improved system up to 56%. 相似文献
108.
William Christian Kayser Gordon E Carstens Ira Loyd Parsons Kevin E Washburn Sara D Lawhon William E Pinchak Eric Chevaux Andrew L Skidmore 《Journal of animal science》2021,99(9)
The objective of this experiment was to determine if statistical process control (SPC) procedures coupled with remote continuous data collection could accurately differentiate between animals experimentally inoculated with a viral–bacterial (VB) challenge or phosphate buffer solution (PBS). Crossbred heifers (N = 38; BW = 230 ± 16.4 kg) were randomly assigned to treatments by initial weight, average daily gain (ADG), bovine herpes virus 1, and Mannheimia haemolytica serum titers. Feeding behavior, dry matter intake (DMI), animal activity, and rumen temperature were continuously monitored remotely prior to and following VB challenge. VB-challenged heifers exhibited decreased (P < 0.01) ADG and DMI, as well as increased (P < 0.01) neutrophils and rumen temperature consistent with a bovine respiratory disease (BRD) infection. However, none of the heifers displayed overt clinical signs of disease. Shewhart and cumulative summation (CUSUM) charts were evaluated, with sensitivity and specificity computed on the VB-challenged heifers (n = 19) and PBS-challenged heifers (n = 19), respectively, and the accuracy was determined as the average of sensitivity and specificity. To address the diurnal nature of rumen temperature responses, summary statistics (mean, minimum, and maximum) were computed for daily quartiles (6-h intervals), and these quartile temperature models were evaluated separately. In the Shewhart analysis, DMI was the most accurate (95%) at deciphering between PBS- and VB-challenged heifers, followed by rumen temperature (94%) collected in the 2nd and 3rd quartiles. Rest was most the accurate accelerometer-based traits (89%), and meal duration (87%) and bunk visit (BV) frequency (82%) were the most accurate feeding behavior traits. Rumen temperature collected in the 3rd quartile signaled the earliest (2.5 d) of all the variables monitored with the Shewhart, followed by BV frequency (2.8 d), meal duration (2.8 d), DMI (3.0 d), and rest (4.0 d). Rumen temperature and DMI remained the most accurate variables in the CUSUM at 80% and 79%, respectively. Meal duration (58%), BV frequency (71%), and rest (74%) were less accurate when monitored with the CUSUM analysis. Furthermore, signal day was greater for DMI, rumen temperature, and meal duration (4.4, 5.0, and 3.7 d, respectively) in the CUSUM compared to Shewhart analysis. These results indicate that Shewhart and CUSUM charts can effectively identify deviations in feeding behavior, activity, and rumen temperature patterns for the purpose of detecting sub-clinical BRD in beef cattle. 相似文献
109.
Sara Frosth Ulrika König Ann-Kristin Nyman Anna Aspán 《Veterinary research communications》2017,41(3):189-193
Dichelobacter nodosus is the principal cause of ovine footrot and strain virulence is an important factor in disease severity. Therefore, detection and virulence determination of D. nodosus is important for proper diagnosis of the disease. Today this is possible by real-time PCR analysis. Analysis of large numbers of samples is costly and laborious; therefore, pooling of individual samples is common in surveillance programs. However, pooling can reduce the sensitivity of the method. The aim of this study was to develop a pooling method for real-time PCR analysis that would allow sensitive detection and simultaneous virulence determination of D. nodosus. A total of 225 sheep from 17 flocks were sampled using ESwabs within the Swedish Footrot Control Program in 2014. Samples were first analysed individually and then in pools of five by real-time PCR assays targeting the 16S rRNA and aprV2/B2 genes of D. nodosus. Each pool consisted of four negative and one positive D. nodosus samples with varying amounts of the bacterium. In the individual analysis, 61 (27.1%) samples were positive in the 16S rRNA and the aprV2/B2 PCR assays and 164 (72.9%) samples were negative. All samples positive in the aprV2/B2 PCR-assay were of aprB2 variant. The pooled analysis showed that all 41 pools were also positive for D. nodosus 16S rRNA and the aprB2 variant. The diagnostic sensitivity for pooled and individual samples was therefore similar. Our method includes concentration of the bacteria before DNA-extraction. This may account for the maintenance of diagnostic sensitivity. Diagnostic sensitivity in the real-time PCR assays of the pooled samples were comparable to the sensitivity obtained for individually analysed samples. Even sub-clinical infections were able to be detected in the pooled PCR samples which is important for control of the disease. This method may therefore be implemented in footrot control programs where it can replace analysis of individual samples. 相似文献
110.
Halimeh Mobarak Ezzatollah Fathi Raheleh Farahzadi Nosratollah Zarghami Sara Javanmardi 《Veterinary research communications》2017,41(1):41-47
Mesenchymal stem cells are undifferentiated cells that have the ability to divide continuously and tissue regeneration potential during the transplantation. Aging and loss of cell survival, is one of the main problems in cell therapy. Since the production of free radicals in the aging process is effective, the use of antioxidant compounds can help in scavenging free radicals and prevent the aging of cells. The aim of this study is evaluate the effects of L-carnitine (LC) on proliferation and aging of rat adipose tissue-derived mesenchymal stem cells (rADSC). rADSCs were isolated from inguinal region of 5 male Rattus rats. Oil red-O, alizarin red-S and toluidine blue staining were performed to evaluate the adipogenic, osteogenic and chondrogenic differentiation of rADSCs, respectively. Flow cytometric analysis was done for investigating the cell surface markers. The methyl thiazol tetrazolium (MTT) method was used to determine the cell proliferation of rADSCs following exposure to different concentrations of LC. rADSCs aging was evaluated by beta-galactosidase staining. The results showed significant proliferation of rADSCs 48 h after treatment with concentrations of 0.2 mM LC. In addition, in the presence of 0.2 mM LC, rADSCs appeared to be growing faster than control group and 0.2 mM LC supplementation could significantly decrease the population doubling time and aging of rADSCs. It seems that LC would be a good antioxidant to improve lifespan of rADSCs due to the decrease in aging. 相似文献