A phytoplasma representative of a new subgroup, 16SrXIII-E, associated with Papaya apical curl necrosis     

Luciano Melo  Eliane Silva  Daniela Flôres  José Ventura  Hélcio Costa  Ivan Bedendo 《European journal of plant pathology / European Foundation for Plant Pathology》2013,137(3):445-450

Papaya apical curl necrosis (PACN) has frequently been observed in several Brazilian states. Affected plants exhibit foliar chlorosis, curvature of the apex, shortening of the internodes leading to bunching of the crown leaves, necrosis of the young apical parts, leaf drop, and dieback. Naturally infected plants were sampled and subjected to PCR assays, which confirmed that a phytoplasma was associated with the disease. Sequencing of the 16S rRNA gene, conventional and computer-simulated RFLP analyses, and phylogenetic analysis allowed the determination of the PACN phytoplasma as a representative of a new subgroup, designated 16SrXIII-E. The phytoplasmas of various 16Sr groups, including 16SrI, 16SrII, 16SrX, 16SrXII, and 16SrXVII, are known to be involved in anomalies in papaya plants in several countries. However, the present study reports, for the first time, the occurrence of a 16SrXIII phytoplasma in association with a papaya disease.  相似文献   

Soil Solution Chemical Response to Two Decades of Experimental Acidification at the Bear Brook Watershed in Maine     

Farrah R. Fatemi  Ivan J. Fernandez  Johanna Szillery  Stephen A. Norton  Lindsey E. Rustad 《Water, air, and soil pollution》2012,223(9):6171-6186

We examined long-term changes in soil solution chemistry associated with experimental, whole watershed-acidification at the Bear Brook Watershed in Maine (BBWM). At BBWM, the West Bear (WB) watershed has been treated with bimonthly additions of ((NH₄)₂ SO₄) since 1989. The adjacent East Bear (EB) watershed serves as a biogeochemical reference. Soil solution chemistry in the EB watershed was relatively stable from 1989?C2007, with the exception of declining SO₄?CS concentrations associated with a progressive decline in SO₄?CS deposition during this period. Soil solution chemistry in WB reflected a progressive change in acid-neutralization mechanisms from base cation buffering to Al buffering associated with treatment during this period. Total dissolved Al concentrations progressively increased over time and were ~4× higher in 2007 than in 1989. Treatment of WB was also associated with long-term increases in soil solution H⁺, SO₄?CS, and NO₃?CN, whereas soil solution dissolved organic carbon (DOC) was unresponsive to treatment. For solutes such as Ca, H⁺, and SO₄?CS, changes in stream chemistry were generally parallel to changes in soil solution chemistry, indicating a close coupling of terrestrial and aquatic processes that regulate the chemistry of solutions in this first-order stream watershed. For other solutes such as Al and DOC, solute concentrations were higher in soil solutions compared with streams, suggesting that sorption and transformation processes along hydrologic flow-paths were important in regulating the chemistry of solutions and the transport of these solutes.  相似文献   

Tomato fruit quality as influenced by the interactions between agricultural techniques and harvesting period          下载免费PDF全文

Marcos Hernández  Francisco Espinosa  Purificación Galindo 《植物养料与土壤学杂志》2014,177(3):443-448

Tomato (Solanum lycopersicum Mill) is an important crop in terms of its economic and nutritional value. Many factors, including cultivar, climate, geography, geochemistry, and agricultural practice, can affect its nutrient concentrations. An HJ‐biplot study was performed to examine the effects of cultivar (Dorothy, Boludo, Dominique, Thomas, and Dunkan), agricultural practices, climatic factors, and their interactions. Significant differences were analyzed using a one‐way ANOVA. All samples were collected and assayed at the same degree of ripeness. In the conventional and organic tomato samples, those harvested from December to April had the highest concentrations of fructose, glucose, citric acid, malic acid, ascorbic acid, protein, Na, and Mg, while those harvested in October had the highest concentrations of lycopene and hydroxycinnamic acid. There were high concentrations of Ca, P, Zn, and Cu in the no‐soil tomatoes. Conventional and organic cultivation practices showed similar results with respect to the collection period, both presenting high organic compound concentrations, while high mineral concentrations seemed to correspond to the no‐soil practice. No clear pattern was observed among the different cultivars, perhaps due to all the samples having been collected at the same degree of ripeness.  相似文献   

In-Laboratory Diffraction-Enhanced X-Ray Imaging of an Equine Hoof     

Daniel P. Fogarty  Benjamin Reinhart  Tochko Tzvetkov  Ivan Nesch  Cooper Williams 《Journal of Equine Veterinary Science》2011,31(7):365-369

We describe and demonstrate the first application of a laboratory-based diffraction-enhanced X-ray imaging instrument for noninvasive equine imaging. A formalin-preserved disarticulated forelimb from a near-term aborted miniature horse fetus was imaged with diffraction-enhanced X-ray imaging. The resultant calculated images—absorption, extinction, refraction, and scattering—are presented, and soft-tissues such as the dorsal digital extensor tendon, articular cartilage, as well as various joint, tendon sheath, and bursa recesses are observed in simultaneous registration with the adjacent dense bone tissue. Radiation dose calculations were performed and a calculated surface dose of 0.6 mGy for the soft muscular tissue was determined for the imaging experiment.  相似文献   

Determining milk isolated and conjugated trans-unsaturated fatty acids using fourier transform Raman spectroscopy     

Stefanov I  Baeten V  Abbas O  Colman E  Vlaeminck B  De Baets B  Fievez V 《Journal of agricultural and food chemistry》2011,59(24):12771-12783

The feasibility of Raman spectroscopy in combination with partial least-squares (PLS) regression for the determination of individual or grouped trans-monounsaturated fatty acids (trans-MUFA) and conjugated linoleic acids (CLA) in milk fat is demonstrated using spectra obtained at two temperature conditions: room temperature and after freezing at -80 °C. The PLS results displayed capability for direct semiroutine quantification of several individual CLA (cis-9,trans-11 and trans-10,cis-12 C18:2) and trans-MUFA (trans-4-15 C18:1) in minor concentrations (below 1.0 g/100 g of milk fat). Calibration models were based on reference data cross-correlation or determined by specific scattering signals in the Raman spectra. Distinct bands for trans-MUFA (1674 cm(-1)) and CLA (1653 cm(-1)) from the trans isolated and cis,trans conjugated C ═ C bonds were identified, as well as original evidence for the temperature effect (new bands, peak shifts, and higher intensities) on the Raman spectra of fatty acid methyl ester and triacylglyceride standards, are supplied.  相似文献   

Comparative analysis of the early transcriptome of Brucella abortus--infected monocyte-derived macrophages from cattle naturally resistant or susceptible to brucellosis     

Rossetti CA  Galindo CL  Everts RE  Lewin HA  Garner HR  Adams LG 《Research in veterinary science》2011,91(1):40-51

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Genetic and immunobiological diversities of porcine reproductive and respiratory syndrome genotype I strains   总被引：1，自引：0，他引：1  

Darwich L  Gimeno M  Sibila M  Diaz I  de la Torre E  Dotti S  Kuzemtseva L  Martin M  Pujols J  Mateu E 《Veterinary microbiology》2011,150(1-2):49-62

Genetic diversity of porcine reproductive and respiratory syndrome virus (PRRSV) has been based on ORF5/GP5 and ORF7/N protein variations. Complete viral genome studies are limited and focused on a single or a few set of strains. Moreover, there is a general tendency to extrapolate results obtained from a single isolate to the overall PRRSV population. In the present study, six genotype-I isolates of PRRSV were sequenced from ORF1a to ORF7. Phylogenetic comparisons and the variability degree of known linear B-epitopes were done considering other available full-length genotype-I sequences. Cytokine induction of all strains was also evaluated in different cellular systems. Non structural protein 2 (nsp2) was the most variable part of the virus with 2 out of 6 strains harboring a 74 aa deletion. Deletions were also found in ORF3 and ORF4. Phylogenetic analyses showed that isolates could be grouped differently depending on the ORF examined and the highest similarity with the full genome cluster was found for the nsp9. Interestingly, most of predicted linear B-epitopes in the literature, particularly in nsp2 and GP4 regions, were found deleted or varied in some of our isolates. Moreover, 4 strains, those with deletions in nsp2, induced TNF-α and 3 induced IL-10. These results underline the high genetic diversity of PRRSV mainly in nsp1, nsp2 and ORFs 3 and 4. This variability also affects most of the known linear B-epitopes of the virus. Accordingly, different PRRSV strains might have substantially different immunobiological properties. These data can contribute to the understanding of PRRSV complexity.  相似文献   

Rainforest litter quality and chemical controls on leaf decomposition with near‐infrared spectrometry     

Scott A. Parsons  Ivan R. Lawler  Robert A. Congdon  Stephen E. Williams 《植物养料与土壤学杂志》2011,174(5):710-720

Plant‐litter chemical quality is an important driver of many ecosystem processes, however, what actually constitutes high‐ or low‐quality litter (chemical potential for fast and slow decomposition, respectively) is often interpreted by the indices available. Here, near‐infrared spectroscopy (NIRS) was used to explore leaf‐litter chemical quality and the controls on decomposition in the tropical rainforest region of north Queensland Australia. Leaf‐litter samples from litterfall collections and litterbag studies were used. NIRS was used to calibrate the chemical compositions of the material (N, P, C, Mg, Ca, acid detergent fiber, acid detergent lignin, α‐cellulose, and total phenolics) from a smaller sample set covering the spectral range in the full set of samples. Calibrations were compared for both separate (local) and combined models, for litterbags, and litterfall. Coefficients of determination (r²) in the local models ranged from 0.88 (litterbag Mg) to 0.99 (litterfall N), with residual prediction deviation ratios > 3 for all constituents except Mg (≈ 2.5). Mass loss in the litterbags was strongly related to the NIR spectra, with model r²'s of 0.75 (in situ leaves) and 0.76 (common control leaf). In situ decomposability was determined from modeling the initial NIR spectra prior to decomposition with litterbag exponential‐decay rates (model r² of 0.81, n = 85 initial samples). A best subset model including litter‐quality, climate, and soil variables predicted decay better than the NIR decomposability model (r² = 0.87). For litter quality alone the NIR model predicted decay rate better than all of the best predictive litter–chemical quality indices. The decomposability model was used to predict in situ decomposability in the litterfall samples. The chemical variables explaining NIR decomposability for litterfall were initial P, C, and phenolics (linear model r² = 0.80, n = 2471). NIRS is a holistic technique that is just as, if not more accurate, than litter–chemical quality indices, when predicting decomposition and decomposability, shown here in a regional field study.  相似文献   

Sociodemographic, health and lifestyle predictors of poor diets   总被引：1，自引：0，他引：1  

Harrington J  Fitzgerald AP  Layte R  Lutomski J  Molcho M  Perry IJ 《Public health nutrition》2011,14(12):2166-2175

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Genetic parameters for fertility traits in Nellore bulls     

Ivan Carvalho Filho  Daniele Botelho Diniz Marques  Carolina Filardi de Campos  José Domingos Guimarães  Simone Eliza Facioni Guimarães  Paulo Sávio Lopes  Fabyano Fonseca e Silva  Renata Veroneze 《Reproduction in domestic animals》2020,55(1):38-43

Nellore is the main cattle breed used in Brazil, being the largest commercial herd in the world. Beyond the importance of male reproductive efficiency for farm profit, the use of reproductive techniques, mainly artificial insemination, turns the evaluation of male reproductive traits even more important. Estimation of genetic parameters increases the knowledge on traits variances and allows envisaging the possibility of the inclusion of new traits as selection criterion. Genetic parameters for fifteen traits that can be classified as testicular biometry or physical and morphological semen traits were estimated for a Nellore bull population ranging from 18 to 36 months. Single-trait and bi-trait animal models were used for (co)variance components estimation. The contemporary group was considered as fixed effect and age at measurement as covariable. Scrotal circumference presented heritability of 0.47 ± 0.12. This value is similar to the heritabilities found for all testicular biometry traits (0.34–0.48). Sperm progressive motility, which has a direct effect on bull fertility, presented low heritability (0.07 ± 0.08). Major and total sperm defects presented moderate to high heritabilities (0.49 ± 0.18 and 0.39 ± 0.15, respectively), indicating that great genetic gain can be obtained through selection against sperm defects. High and positive genetic correlations were observed among testicular biometry traits, which also presented favourable genetic correlations with physical and morphological traits of the semen with magnitude ranging from high to low. Scrotal circumference presented moderate to high and favourable genetic correlations with sperm progressive motility, sperm turbulence, major sperm defects and total sperm defects. Thus, the selection for scrotal circumference results in favourable correlated genetic response for semen quality. The results show that the use of scrotal circumference as reference trait for bull fertility is appropriate, since it presents high heritability and favourable genetic correlation with semen quality.  相似文献