A Combination of Baiting and Different PCR Formats, Including Measurement of Real-Time Quantitative Fluorescence, For the Detection of Phytophthora fragariae in Strawberry Plants

Phytophthora fragariae, the cause of strawberry red stele disease, is a quarantine pathogen in Europe. Detecting low levels of infection requires sensitive and specific methods. In the past, Dutch and English inspection services have used bait plants to test strawberry propagation stocks destined for export. Increasingly though, PCR is being incorporated into these testing procedures in an effort to increase sensitivity and speed. Various combinations of baiting and PCR assays were compared with existing testing procedures. Water and root samples from the bait test were screened by nested PCR and the PCR amplicon was detected by several methods, including fluorescent labelled probes (TaqMan and Molecular Beacon). PCR amplification was monitored in real-time and semi-quantitative detection was possible. Because PCR reactions are sensitive to inhibitors present in extracted DNA samples, an internal control containing the primer sequences specific for P. fragariae was developed to avoid false negatives.     

THE RHESUS MONKEY

Transbronchoscopic inoculation of five serotypes of Streptococcus pneumoniae was used to produce pneumonia in five rhesus monkeys. The development and resolution of the pneumonia were followed radiographically and clinically. The initial inoculation determined the lung lobes that would become involved. The acute state was accompanied by a febrile response, leukocytosis, and bacteremia. Resolution of the pneumonia occurred in six weeks. The radiographic features of spontaneous streptococcal pneumonia in rhesus monkeys were similar but not identical to those found in man. However, extension to other lobes, mediastinal lymphadenopathy, and extensive pleural effusion, as often noted in the human, were not identified. The rhesus monkey is thought to be a good animal model for the radiographic evaluation of streptococcal pneumonia.     

Non-target effects of dimethoate and acephate against Eusieus tularensis Congdon and Aphytis melinus DeBach on lemons in California

Understanding the non-target effects on pesticides used in crop production systems is essential for the development of IPM programmes in those systems. Two organophosphates for control of citrus thrips in citrus were compared at commercial field rates in a lemon orchard for their effect against a predacious mite and a parasitic wasp, both of which have a significant role in coastal lemon IPM. Dimethoate and acephate greatly reduced populations of both beneficial insects, holding them to below detectable levels for 8 weeks post-treatment. Moreover, citrus red mite, a secondary pest, developed beyond the economic treatment threshold in both the dimethoate and acephate plots 10 weeks and 4 weeks post-treatment, respectively. In addition to predatory mite mortality, hormoligosis is suspected in both instances, and especially with acephate, of causing this secondary pest problem.     

Cortical Osteitis of The Humeral Diaphysis Caused by Rhodococcus Equi

Infection with Rhodococcus equi is a common cause of pneumonia in foals. Extrapulmonary manifestations occur, including gastrointestinal disease such as enterocolitis, musculoskeletal disease such as osteomyelitis, as well as other aberrant regions of abscess. Osteomyelitis predominately occurs in the metaphyseal or epiphyseal regions of long bones because of low-pressure blood flow through the sinusoids of these regions of the bone. In this report, a case of cortical, diaphyseal osteitis of the humerus caused by Rhodococcus equi and subsequent medical and surgical management is described.     

Plant Colonization and Arsenic Uptake on High Arsenic Mine Wastes, New Zealand

Substrates associated with two historic gold mining sites in north Westland, New Zealand, have locally very high arsenic concentrations (commonly 10–40 wt% As). The substrates consist of iron oxyhydroxide precipitates, and processing mill residues. Waters associated with some of these substrates have high dissolved arsenic (commonly 10–50 mg/L As). Natural revegetation of these very high arsenic sites has occurred over the past 50 years, although some areas of substrate remain bare. Revegetating species include native and adventive shrubs, adventive grasses, rushes, and mosses, and native ferns. Revegetation by higher plants follows initial colonization by mosses, and some shrubs are growing directly in high-arsenic substrate. Shrubs, especially manuka (Leptospermum scoparium), gorse (Ulex europaeus), tree fuchsia (Fuchsia excorticata) and broadleaf (Griselinia littoralis) largely exclude arsenic from their shoots (<?10 mg/kg dry weight) irrespective of the As content of the substrate. Likewise, most grasses, and reeds (Juncus spp.), have only modest As contents (typically <?100 mg/kg dry weight). However, mosses growing on high-arsenic substrates have strongly elevated arsenic contents (>?0.2% dry weight). In particular, the moss Pohlia wahlenbergii acts as a hyperaccumulator, with up to 3% (dry weight) As. Antimony (Sb) contents of all plants are about one thousandth of that of arsenic, reflecting the As/Sb ratio of the substrates. Plant establishment in the high-As substrates may be locally limited by low nutrient status, rather than arsenic toxicity. The shrubs, grasses, and reeds identified in this study are arsenic tolerant and largely exclude arsenic from their shoots so that revegetation with these species, can help to isolate the high-arsenic substrates from the surface environment. These species could be used as phytostabilisation agents on high-arsenic sites that are remote from human habitation. In contrast, the mosses, despite their high arsenic tolerance, are a less desirable component of revegetation of high-arsenic substrates because they actively transfer arsenic from the substrate to the biosphere.     

Decomposition of C-labeled roots in a pasture soil exposed to 10 years of elevated CO2

The net flux of soil C is determined by the balance between soil C input and microbial decomposition, both of which might be altered under prolonged elevated atmospheric CO₂. In this study, we determined the effect of elevated CO₂ on decomposition of grass root material (Lolium perenne L.). ¹⁴C-labeled root material, produced under ambient (35 Pa pCO₂) or elevated CO₂ (70 Pa pCO₂) was incubated in soil for 64 days. The soils were taken from a pasture ecosystem which had been exposed to ambient (35 Pa pCO₂) or elevated CO₂ (60 Pa pCO₂) under FACE-conditions for 10 years and two fertilizer N rates: 140 and 560 kg N ha⁻¹ year⁻¹. In soil exposed to elevated CO₂, decomposition rates of root material grown at either ambient or elevated CO₂ were always lower than in the control soil exposed to ambient CO₂, demonstrating a change in microbial activity. In the soil that received the high rate of N fertilizer, decomposition of root material grown at elevated CO₂ decreased by approximately 17% after incubation for 64 days compared to root material grown at ambient CO₂. The amount of ¹⁴CO₂ respired per amount of ¹⁴C incorporated in the microbial biomass (q¹⁴CO₂) was significantly lower when roots were grown under high CO₂ compared to roots grown under low CO₂. We hypothesize that this decrease is the result of a shift in the microbial community, causing an increase in metabolic efficiency. Soils exposed to elevated CO₂ tended to respire more native SOC, both with and without the addition of the root material, probably resulting from a higher C supply to the soil during the 10 years of treatment with elevated CO₂. The results show the importance of using soils adapted to elevated CO₂ in studies of decomposition of roots grown under elevated CO₂. Our results further suggest that negative priming effects may obscure CO₂ data in incubation experiments with unlabeled substrates. From the results obtained, we conclude that a slower turnover of root material grown in an ‘elevated-CO₂ world’ may result in a limited net increase in C storage in ryegrass swards.     

International surveillance of wheat rust pathogens: progress and challenges

Surveillance of wheat rust pathogens, including assessments of rust incidence and virulence characterization via either trap plots or race (pathotype) surveys, has provided information fundamental in formulating and adopting appropriate national and international policies, investments and strategies in plant protection, plant breeding, seed systems, and in rust pathogen research. Despite many successes from national and regional co-ordination of rust surveillance, few attempts were made to extend rust surveillance to international or even global levels. The Global Cereal Rust Monitoring System was established to address this deficiency. It is underpinned by an information platform that includes standardized protocols for methods and systems used in surveys, preliminary virulence testing, data, sample transmission and management at the field and national and global levels, and includes two web-based visualization tools. While considerable progress has been made towards a global system for monitoring variability in the wheat stem rust pathogen, and linking this to the threat posed by this pathogen to regional wheat production, some challenges remain, including ongoing commitment to support rust surveillance, and the ability to share and compare surveillance data.     

Supernova shock breakout from a red supergiant

Massive stars undergo a violent death when the supply of nuclear fuel in their cores is exhausted, resulting in a catastrophic "core-collapse" supernova. Such events are usually only detected at least a few days after the star has exploded. Observations of the supernova SNLS-04D2dc with the Galaxy Evolution Explorer space telescope reveal a radiative precursor from the supernova shock before the shock reached the surface of the star and show the initial expansion of the star at the beginning of the explosion. Theoretical models of the ultraviolet light curve confirm that the progenitor was a red supergiant, as expected for this type of supernova. These observations provide a way to probe the physics of core-collapse supernovae and the internal structures of their progenitor stars.