Alkaline hydrolyzable nitrogen and properties that dictate its distribution in paddy soil profiles

Nitrogen (N) is a key nutrient for rice production, and its bioavailability in paddy soils is strongly coupled to soil organic matter (SOM) cycling. A better understanding of potentially available N forms in soil, such as alkaline hydrolyzable N (AH-N), and their depth distribution will support the development of best management practices to improve the N use efficiency of rice while minimizing adverse environmental effects. Fifteen rice (Oryza sativa L.) fields from Southern Brazil were selected, and stratified soil samples were taken to a depth of 60 cm before crop establishment. Selected soil physical and chemical properties were analyzed to evaluate their relationships with AH-N contents in the soil profile. The AH-N contents below 20 cm varied extensively (increased, reduced, or constant) compared with that above 20 cm. Although clay and clay + silt contents were highly correlated to AH-N for some soils, the major property dictating AH-N distribution by depth was total N (TN), as the correlation between TN and AH-N was mainly by direct effect. The proportion of TN recovered as AH-N across sites and depths presented high amplitude, and thus AH-N was not a constant N pool across depths, indicating that AH-N can be affected by soil management practices even when TN showed no major changes. The distinct distribution of AH-N across soil sampling sites and depths indicates that depths greater than 20 cm should be considered when calibrating the AH-N index for N fertilizer recommendations for flooded rice in Southern Brazil.     

Importance of heat shock proteins in maize

Abiotic and biotic stress conditions cause extensive losses to maize production, mainly due to protein dysfunction in these conditions. In higher plants, the occurrence of heat-shock proteins (HSPs) in response to different environmental stresses is a universal phenomenon and has been well documented. Many studies have demonstrated that most HSPs are involved in many regulatory pathways, act as molecular chaperones for other cell proteins, and have strong cytoprotective effects. Although many functional roles for HSPs are known, the mechanisms for these multiple functions are not entirely understood. Here we reviewed the correlation among HSP genes/proteins and plant tolerance, especially maize, in different environmental stresses. Due to the low availability of information regarding the expression of HSP genes in response to different stresses in maize, we decided to mine databases in order to generate new insights related to this topic.     

Pharmacokinetic study of nobiletin and tangeretin in rat serum by high-performance liquid chromatography-electrospray ionization-mass spectrometry

Nobiletin (NOB) and tangeretin (TAN), two of the main polymethoxylated flavones (PMFs) in citrus, influence a number of key biological pathways in mammalian cells. Although the impacts of NOB and TAN on glucose homeostasis and cholesterol regulation have been investigated in human clinical trials, much information is still lacking about the metabolism and oral bioavailability of these compounds in animals. In this study, NOB and TAN were administered to rats by gavage and intraperitoneal (ip) injection, and the blood serum concentrations of these compounds and their main metabolites were monitored by high-performance liquid chromatography-electrospray ionization-mass spectrometry (HPLC-ESI-MS). In addition to the administered compounds, two metabolites of TAN and eight metabolites of NOB were detected and measured over 24 h. With identical oral doses, nearly 10-fold higher absorption of NOB occurred compared to TAN. For both compounds, maximum levels of glucuronidated metabolites occurred in the blood serum at later time points (～5-8 h) compared to the earlier T(max) values for NOB and TAN. In most cases the glucuronides occurred at substantially higher concentrations than the aglycone metabolites. Low levels of NOB and TAN and their metabolites were detectable in rat blood serum even at 24 h after treatment.     

Avian paramyxovirus type 1 infections in racing pigeons in California. I. Clinical signs, pathology, and serology.

An outbreak of diarrhea and neurological disease in California racing pigeons caused by avian paramyxovirus type 1 (PMV-1) is documented. Predominant clinical signs were polydipsia, ataxia, poor balance, torticollis, head tremors, inability to fly, and diarrhea that was unresponsive to therapy. Gross pathologic findings were often unremarkable or non-specific. The predominant histologic lesions were interstitial nephritis, chronic tubular necrosis, lymphoplasmacytic infiltration within the kidney, liver, and pancreas, and focal non-suppurative encephalitis. Pigeons from 20 submissions demonstrated characteristic clinical signs of PMV-1 infection. Pigeons from 17 submissions exhibited typical histopathology. Serologic evidence of PMV-1 infection was present in pigeons from 13 submissions, and PMV-1 was isolated from pigeons received in six submissions. None of these pigeons had been vaccinated against PMV-1.     

Silicon amendment improves wheat defence against Fusarium graminearum and complements the control by fungicide of Fusarium head blight

A three-year field experiment with two wheat cultivars evaluated the effect of soil-applied silicon (Si), with and without fungicide spraying, on Fusarium head blight (FHB) control. Silicon treatment alone reduced FHB severity and the percentage of damaged wheat kernels, regardless of the cultivar. The best disease control was obtained for the cultivar with moderate disease resistance (MR), supplied with silicon and treated with fungicide during flowering. Silicon treatment alone promoted an increase in deoxynivalenol (DON) concentration in the disease-susceptible cultivar; however, in the MR cultivar, silicon amendment associated with fungicide treatment led to a reduction in DON concentration. Greenhouse experiments evaluated the effect of silicon combined with different timings of fungicide application on wheat defences against Fusarium graminearum. Plants supplied with silicon had a longer pathogen incubation period, lower FHB severity and lower DON concentration when compared to plants without silicon. In addition, silicon-supplied plants had higher soluble phenolic content and altered antioxidant enzyme activities (SOD, CAT, POX and PPO) that favoured early accumulation of hydrogen peroxide when compared to plants without silicon. Greater control of FHB and lower DON concentration in plants treated with silicon and fungicide before inoculation and up to 1 day after inoculation was associated with increased levels of defence-associated metabolites. Silicon contributed to the reduction of FHB and DON concentration in wheat, especially for the MR cultivar and, when combined with fungicide spraying, both MR and disease-susceptible cultivars had enhanced performances upon silicon amendment.     

ASVCP quality assurance guidelines: external quality assessment and comparative testing for reference and in‐clinic laboratories

The purpose of this document is to educate providers of veterinary laboratory diagnostic testing in any setting about comparative testing. These guidelines will define, explain, and illustrate the importance of a multi‐faceted laboratory quality management program which includes comparative testing. The guidelines will provide suggestions for implementation of such testing, including which samples should be tested, frequency of testing, and recommendations for result interpretation. Examples and a list of vendors and manufacturers supplying control materials and services to veterinary laboratories are also included.     

Genetic diversity of papaya (Carica papaya L.) F5 recombinant inbred lines using the Ward-MLM strategy

Genetic Resources and Crop Evolution - The development of segregating populations in papaya allows the development of new high fruit yield and excellent fruit quality pure line or hybrid cultivars....     

Modelling Wild-Oat Density in Terms of Soil Factors: A Machine Learning Approach

In crop fields, weed density varies spatially in non-random patterns. Initial knowledge of weed distribution would greatly improve weed management for Precision Agriculture operations. Site properties could be correlated to weed distribution, since the former vary among crop fields and also certain factors such as soil texture or nitrogen may condition the weed growth. This paper presents a method, based on artificial intelligence techniques, for inducing a model that appropriately predicts the heterogeneous distribution of wild-oat (Avena sterilis L.) in terms of some environmental variables. From several experiments, distinct rule sets have been found by applying a genetic algorithm to carry out the automatic learning process. The best rule set extracted was able to explain about 88% of weed variability.