Detection of Ureaplasma diversum in the upper airways of Australian feedlot cattle

Bovine respiratory disease (BRD) exerts a major impact on the beef cattle industry nationally and worldwide, with a range of aetiological factors impacting its pathogenesis. Previous research has focussed on an increasing number of bacteria and viruses that have been shown to play a role in eliciting disease. Recently, additional agents have been emerging as potential contributors to BRD, including the opportunistic pathogen Ureaplasma diversum. To determine if U. diversum was present in Australian feedlot cattle and if that presence was linked to BRD, nasal swabs were collected from a cohort of 34 hospital pen animals and compared to 216 apparently healthy animals sampled contemporaneously at feedlot induction and again after 14 days on feed at an Australian feedlot. All samples were subjected to a de novo polymerase chain reaction (PCR) assay targeting U. diversum in combination with other BRD agents. U. diversum was detected at a low prevalence in cattle at induction (Day 0: 6.9%, Day 14: 9.7%), but in a significantly greater proportion of cattle sampled from the hospital pen (58.8%). When considering the presence of other BRD-associated agents, co-detection of U. diversum and Mycoplasma bovis was most common in hospital pen animals receiving treatment for BRD. These findings suggest that U. diversum may be an opportunistic pathogen involved in the aetiology of BRD in Australian feedlot cattle, in combination with other agents, with further studies are warranted to identify if a causal relationship exists.     

The carbon content of soil and its geographical distribution in Great Britain

Abstract. England and Wales have 155 314 1 × 1 km squares, of which 140049 have more than 50% soil cover. The total soil organic carbon content, based on the dominant soil series and dominant land cover type, is estimated to be 2773 × 10⁶ t C. Scotland has 84929 1 × 1 km squares, of which 82 420 have a nominated dominant soil series. The total soil organic carbon content is estimated to be 19011 × 10⁶ t C, 6.85 times the total organic carbon content of the soil of England and Wales. The total organic carbon content of the soil of Great Britain is estimated to be 21 784 × 10⁶ t C, of which 87% is in Scottish soils and 75% is in Scottish peats. A map of the mean soil organic carbon content of 10 × 10 km squares of the National Grid using classes of equal range illustrates the narrow range of organic carbon contents of the soils of England and Wales and the dominance of organic carbon in Scottish soils. A map using the same data, but with classes of unequal ranges increasing in size with increasing carbon content, is better for showing detailed differences within England and Wales.     

Effect of auxin,cytokinin, and glutamine on mycelial growth of Phaeolus schweinitzii

The effect of naphthaleneacetic acid (NAA), benzylaminopurine (BAP), L-glutamine (L-gln), and combinations of these substances on mycelial growth of Phaeolus schweinitzii was studied in vitro. NAA (1 mg × 1^?1), L-gln (500 mg × 1^?1) and a combination of NAA with L-gln inhibited the growth of fungal mycelium. BAP (1 mg × 1^?1) enhanced the inhibitory effect of NAA while in combination with L-gln it reduced the inhibitory effect of L-gln.     

Effects of prior vegetative growth, inoculum density, light, and mating on conidiation of Erysiphe necator

Initiation of asexual sporulation in powdery mildews is preceded by a period of superficial vegetative growth of mildew colonies. We found evidence of a quorum-sensing signal in Erysiphe necator that was promulgated at the colony center and stimulated conidiation throughout the colony. Removal of the colony center after putative signal promulgation had no impact upon timing of sporulation by 48-h-old hyphae at the colony margin. However, removal of the colony center before signaling nearly doubled the latent period. A relationship between inoculum density and latent period was also observed, with latent period decreasing as the number of conidia deposited per square millimeter was increased. The effect was most pronounced at the lowest inoculum densities, with little decrease of the latent period as the density of inoculation increased above 10 spores/mm. Furthermore, light was shown to be necessary to initiate conidiation of sporulation-competent colonies. When plants were inoculated and maintained in a day-and-night cycle for 36 h but subjected to darkness after 36 h, colonies kept in darkness failed to sporulate for several days after plants kept in light had sporulated. Once returned to light, the dark-suppression was immediately reversed, and sporulation commenced within 12 h. Merging of colonies of compatible mating types resulted in near-cessation of sporulation, both in the region of merging and in more distant parts of the colonies. Colonies continued to expand but stopped producing new conidiophores once pairing of compatible mating types had occurred, and extant conidiophores stopped producing new conidia. Therefore, in addition to a quorum-sensing signal to initiate conidiation, there appears to be either signal repression or another signal that causes conidiation to cease once pairing has occurred and the pathogen has initiated the ascigerous stage for overwintering.     

Spatial interpretation of plant parameters in winter wheat

A methodology is described for the spatial interpretation of plant parameters (SIOPP), which was used to diagnose the nutritional status of winter wheat. The data used in this study were collected in 2010 throughout the monitoring of two fields (52 and 38 ha) with uniform and conventional agricultural management, located in the Czech Republic. The survey was carried out at BBCH 30 phenological stage in a regular sampling grid with 150 m of distance between grid points (27 and 18 samples). The plant height and the chlorophyll concentration (Yara N-Tester) were recorded. Plant and soil samples were taken to analyse the nutrient concentrations (N, P, K, Mg, Ca, and S). A crop development index (CDI) was developed combining plant height and N-Tester values to quantify the growth of the plant (biomass and vigour). The relationship between this index and the concentration of nutrients were studied and confirmed by cross-validation and spatial analysis; the aim was to determine the factors that limit plant growth. The method revealed the limiting factors in field #1 were potassium, calcium (pH problems) and nitrogen (in descending order of relevance). In field #2, CDI was only related to the soil moisture. In all cases, it was found that the spatial variability of the indices and the limiting factors followed a pattern result of the combination of the gradients in climate, topography and soils of each field. This allowed the interpolation of the maps for variable-rate application using only 0.5 samples per hectare arranged in regular mesh, which was insufficient for the use of geostatistics. All diagnoses were consistent with the crop yield, the soil sampling and the DRIS diagnoses. The results showed that if leaf analyses are complemented with a few additional measures, instantaneous and with a minimal cost, it is possible to deduce the diagnosis using statistical and spatial analysis.     

小麦化学杀雄制种不同行向、不同行比田间异交结实率研究

以3.33hm~2为参试单位,40hm~2亩不同播种方式、不同父母本比例小麦化学杀雄田间制种观察表明:(1).同一播种行向,父母本比例1:1(田间播幅1.8m:1.8m)与1:2(1.8m:3.6m)间结实率无显著差异;(2).不同播种方式南北行向与东西行向间,父母本比例无论1     

Pseudomonas syringae pv. syringae from cool climate Australian grapevine vineyards: new phylogroup PG02f associated with bacterial inflorescence rot

During the period 2006–2011, Pseudomonas syringae pv. syringae caused a bacterial inflorescence rot (BIR) epidemic in an Australian cool climate viticultural region. Molecular multilocus sequence typing of ‘housekeeping’ genes (MLST), biochemical testing and analysis of molecular variance (AMOVA) were used to characterize the genotypes and phenotypes of P. syringae pv. syringae grapevine isolates. Comparison of the MLST data with exemplars of phylogroups available at PAMDB demonstrated that the BIR isolates formed a new clade within P. syringae pv. syringae phylogroup 2 (PG02): putatively designated PG02f. Analysis of the MLST and phenotypic data by AMOVA demonstrated some genetic differences between the BIR isolates and the general vineyard P. syringae pv. syringae population. Isolates positive for syringopeptin, syringomycin and tyrosinase, tobacco leaf hypersensitivity reaction (HR), ampicillin resistance and grapevine leaf pathogenicity were genetically distinct from those negative for these factors. This study has shown that, generally, the core genome of P. syringae pv. syringae is only weakly associated with the virulence-associated traits. As the new phylogroup PG02f consists of the epidemic BIR isolates and nonpathogenic grapevine isolates, these genetically similar isolates differ greatly in pathogenicity and most of the other tested phenotypic traits. However, within the PG02f group, tobacco leaf HR and presence of sylC (the gene for phytotoxin syringolin A) are associated with the BIR and bacterial leaf spot (BLS) isolates, and negative for the nonpathogens, indicating that these two virulence factors may be associated with vineyard pathogenicity within the new Australian phylogroup.