Possible methionine biosynthesis inhibition by pyrimidinamine fungicides

The broad-spectrum fungicide CGA 219417 inhibits mycelial growth of Botrytis cinerea Pers ex Fr. Pseudocercosporella herpotrichoides (Fron.) Deighton and Helminthosporium oryzae B. de Haan on defined media lacking amino acids. The growth inhibition of B. cinerea is reversed by the addition of a mixture of 19 amino acids at a concentration of 100 μM each or by the addition of methionine or homocysteine in concentrations of 100 μM or 1 mM, respectively. In the case of B. cinerea, the reversal of growth inhibition by methionine could also be shown for pyrimethanil and mepanipyrim. These findings suggest that the pyrimidinamine fungicides inhibit the biosynthesis of methionine in phytopathogenic fungi.     

Monitoring infection with Piscine myocarditis virus and development of cardiomyopathy syndrome in farmed Atlantic salmon (Salmo salar L.) in Norway

An epidemiological study was carried out in Norway in 2015–2018, investigating the development of infection with Piscine myocarditis virus (PMCV) and development of cardiomyopathy syndrome (CMS) in farmed Atlantic salmon. Cohorts from 12 sites were followed and sampled every month or every other month from sea transfer to slaughter. PMCV was detected at all sites and in all sampled cages, and fish in six sites developed clinical CMS. The initial infection happened between 1 and 7 months post‐sea transfer, and the median time from infection with PMCV until outbreak of CMS was 6.5 months. Generally, fish from sites with CMS had higher viral titre and a higher prevalence of PMCV, compared to sites that did not develop clinical CMS. The virus persisted until the point of slaughter at most (11 out of 12) of the sites. The detection of PMCV in all sites suggests that PMCV is more widespread than previously known. Screening for PMCV as a tool to monitor impending outbreaks of CMS must be supported by observations of the health status of the fish and risk factors for development of disease.     

Sensitivity of ecosystem goods and services projections of a forest landscape model to initialization data

Projections of indicators of forest ecosystem goods and services (EGS) based on process-based landscape models are critical for adapting forest management to climate change. However, the scarcity of fine-grained, spatially explicit forest data means that initializing these models is both a challenge and a source of uncertainty. To test how different initialization approaches influence the simulation of forest dynamics and EGS indicators we initialized the forest landscape model LandClim with fine resolution empirical data, coarse empirical data, and simulation-derived data, and evaluated the results at three spatial scales (stand, management area and landscape). Simulations were performed for a spruce (Picea abies) dominated landscape in the Black Forest, Germany, under current climate and a climate change scenario. We found that long-term (>150 years) projections are robust to initialization uncertainty. In contrast, shorter-term projections are sensitive to initialization uncertainty, with sensitivity increasing when EGS are assessed at smaller spatial scales, and when the EGS indicators depend on the spatial distribution of individual species. EGS dynamics are strongly influenced by interactions between the density, species composition, and age structure of initialized forests and simulated forest management. If EGS dynamics are strongly influenced by climate change, such as when climate change induces mortality in drought-sensitive species, some of the initialization uncertainty can be masked. We advocate for initializing landscape models with fine-grained data in applications that focus on spatial management problems in heterogeneous landscapes, and stress that the scale of analysis must be in accordance with the accuracy that is warranted by the initialization data.     

Impact of biochar coated with magnesium (hydr)oxide on phosphorus leaching from organic and mineral soils

Purpose

Recent research suggests that Swedish organic arable soils have been under-recognized as a potential source of phosphorus (P) loading to water bodies. The aim of this study was to compare P losses through leaching from organic and high-fertility mineral soils. In addition, the effectiveness of a magnesium-salt-coated biochar applied below the topsoil as a mitigation strategy for reducing P losses was evaluated.

Materials and methods

Phosphorus leaching was measured from four medium- to high-P arable soils, two Typic Haplosaprists (organic 1 and 2), a Typic Hapludalf (sand), and an unclassified loam textured soil (loam), in a 17-month field study utilizing 90-cm-long lysimeters. A magnesium-salt-coated biochar was produced and characterized using X-ray powder diffraction (XPD), scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS), and X-ray adsorption (XANES) spectroscopy, and its phosphate adsorption capacity was determined at laboratory scale. It was also applied as a 3-cm layer, 27 cm below the soil surface of the same lysimeters and examined as a mitigation measure to reduce P leaching.

Results and discussion

Total-P loads from the 17-month, unamended lysimeters were in the order of organic 2 (1.2 kg ha^?1)?>?organic 1 (1.0 kg ha^?1)?>?sand (0.3 kg ha^?1)?>?loam (0.2 kg ha^?1). Macropore flow, humic matter competition for sorption sites, and fewer sorption sites likely caused higher P losses from the organic soils. Analysis by XRD and SEM revealed magnesium was primarily deposited as periclase (MgO) on the biochar surface but hydrated to brucite (Mg(OH)₂) in water. The Langmuir maximum adsorption capacity (Q_max) of the coated biochar was 65.4 mg P g^?1. Lysimeters produced mixed results, with a 74% (P?<?0.05), 51% (NS), and 30% (NS) reduction in phosphate-P from the organic 1, organic 2, and sand, respectively, while P leaching increased by 230% (NS) from the loam.

Conclusions

The findings of this study indicate that P leached from organic arable soils can be greater than from mineral soils, and therefore, these organic soils require further investigation into reducing their P losses. Metal-enriched biochar, applied as an adsorptive layer below the topsoil, has the potential to reduce P losses from medium- to high-P organic soils but appear to be less useful in mineral soils.

     

Actinomycetes from sediments in the Trondheim fjord, Norway: diversity and biological activity

The marine environment represents a largely untapped source for isolation of new microorganisms with potential to produce biologically active secondary metabolites. Among such microorganisms, Gram-positive actinomycete bacteria are of special interest, since they are known to produce chemically diverse compounds with a wide range of biological activities. We have set out to isolate and characterize actinomycete bacteria from the sediments in one of the largest Norwegian fjords, the Trondheim fjord, with respect to diversity and antibiotic-producing potential. Approximately 3,200 actinomycete bacteria were isolated using four different agar media from the sediment samples collected at different locations and depths (4.5 to 450 m). Grouping of the isolates first according to the morphology followed by characterization of isolates chosen as group representatives by molecular taxonomy revealed that Micromonospora was the dominating actinomycete genus isolated from the sediments. The deep water sediments contained a higher relative amount of Micromonospora compared to the shallow water samples. Nine percent of the isolates clearly required sea water for normal growth, suggesting that these strains represent obligate marine organisms. Extensive screening of the extracts from all collected isolates for antibacterial and antifungal activities revealed strong antibiotic-producing potential among them. The latter implies that actinomycetes from marine sediments in Norwegian fjords can be potential sources for the discovery of novel anti-infective agents.     

Right flank laparotomy and abomasotomy for removal of a phytobezoar in a standing cow

A 4.5-year-old Holstein-Friesian cow underwent surgery because of left abomasal displacement. Intra-operative palpation of the pyloric region revealed a phytobezoar. The abomasum containing the phytobezoar was exteriorized, and an incision was made directly over the mass in the region of the greater curvature of the pyloric part of the abomasum.     

Structural diversity of English yew (<Emphasis Type="Italic">Taxus baccata</Emphasis> L.) populations

In Europe, the English yew species (Taxus baccata L.) is endangered. Intensive human land-use, including forest management, has caused a decrease of the yew populations all over Europe. In Austria, gene conservation forests are used for the in situ conservation of populations of this rare tree species by silvicultural treatments. In order to improve the conservation management in these gene conservation forests, this study addresses the relation between competition and viability of yew populations through the use of structural diversity indices. The structural indices, which include mingling, tree–tree distance, diameter, and tree height differentiation, were determined for a structural group of four trees as well as the neighbouring trees of the male and female yews at the monitoring plots on a regular grid in three gene conservation forests. Although the three study sites provided quite different environmental conditions for English yew, the vitality of each individual yew was influenced by the inter-specific competition of the neighbouring tree species at all sites. Low vitality was associated with a small mean distance to neighbours and large tree height differentiation. In conclusion, we suggest that a combination of different structural indicators is needed for an integrative assessment of conservation status in the gene conservation forests. This would help improve the evaluation of the impact management has on yew population viability.     

Piscine orthoreovirus (PRV) in red and melanised foci in white muscle of Atlantic salmon (Salmo salar)

Melanised focal changes (black spots) are common findings in the white skeletal muscle of seawater-farmed Atlantic salmon (Salmo salar). Fillets with melanised focal changes are considered as lower quality and cause large economic losses. It has been suggested that red focal changes (red spots) precede the melanised focal changes. In the present work, we examined different populations of captive and wild salmon for the occurrence of both types of changes, which were investigated for the presence of different viruses by immunohistochemistry and RT-qPCR. The occurrence of red or melanised foci varied significantly between the populations, from none in wild fish control group, low prevalence of small foci in fish kept in in-house tanks, to high prevalence of large foci in farm-raised salmon. Large amounts of Piscine orthoreovirus (PRV) antigen were detected in all foci. No other viruses were detected. Red focal changes contained significantly higher levels of PRV RNA than apparently non-affected areas in white muscle of the same individuals. Some changes displayed a transient form between a red and melanised pathotype, indicating a progression from an acute to a chronic manifestation. We conclude that PRV is associated with the focal pathological changes in the white muscle of farmed Atlantic salmon and is a premise for the development of focal melanised changes.     

IMAGING DIAGNOSIS—RADIOGRAPHY AND COMPUTED TOMOGRAPHY OF RADIOULNAR ISCHEMIC NECROSIS IN A JACK RUSSELL TERRIER

A 7‐year‐old Jack Russell Terrier with a history of minor trauma was presented for lameness of the left forelimb. Radiography and computed tomography demonstrated a localized radioulnar osteolytic lesion with cortical bone loss and enthesiophytes. Based on results of diagnostic imaging and histopathological examination, the final diagnosis was radioulnar ischemic necrosis (RUIN), complicated by pathologic fracture. A rare disorder of unknown etiology, RUIN may be secondary to tearing of the interosseous ligament and potential ischemia. It should be differentiated from neoplastic or fungal disease. To the authors´ knowledge, this is the first canine case report describing RUIN.     

Colonization of sugarcane plantlets by mixed inoculations with diazotrophic bacteria

Micropropagated sugarcane plants have been used in Brazil for almost three decades. Besides the improvement in plant health, micropropagated sugarcane carries no endophytic plant growth-promoting bacteria. The Brazilian inoculation technology to reintroduce diazotrophic bacteria in micropropagated sugarcane plantlets revealed a synergistic-like effect in PGP-bacteria mixed inoculations. The infection model of single diazotrophic bacteria species in sugarcane was studied in detail, but still many questions remain open. In this study we used a combined fluorescence in situ hybridization (FISH) and a cultivation based approach (MPN) to evaluate the colonization of sugarcane plantlets by mixed inocula. The highest colonization for three out of the five species studied was obtained with a mixed inoculum, when the Azospirillum amazonense showed an increase by almost 100 times in colonization and Herbaspirillum spp. and Burkholderia tropica was determined at 10⁷ cells per gram root fresh weight. All of the inoculated bacterial species could be detected using the FISH probes 12 h after bacterial inoculation. The FISH results confirmed the MPN counts and showed differences in the population numbers and colonization behavior of particular bacterial inoculum strains in the different mixed inocula. A putative antagonistic effect among the inoculated H. seropedicae and H. rubrisubalbicans strains was observed using FISH, as well as the better competitiveness of B. tropica as compared to the A. amazonense strain. The observed data probably reflect also specific interactions with the sugarcane variety used in this particular inoculation system, and may not be generalized as a rule. This is the first study about the competition for sugarcane colonization in a mixed bacterial inoculum.