Rapid virulence typing of Pasteurella multocida by multiplex PCR

The gram-negative bacterium Pasteurella multocida constitutes a heterogeneous species associated with wide range of disease in many animals. Isolates are classified into five groups based on capsular antigen (capA, B, D, E and F). Recently, a new valuable PCR-based method was introduced to determine the epidemiological correlation between P. multocida infection and existence of virulence genes including tbpA, pfhA, toxA and hgbB. However, this method is tedious and laborious. Thus, in the current study, we designed a reliable multiplex PCR method for rapid detection of virulence genes in P. multocida. Eighty seven strains of P. multocida isolated from various clinically healthy and infected hosts were examined by uniplex PCR method for each virulence associated genes. Based on our improved and simplified multiplex PCR method, rapid detection of four virulence genes was accomplished. It is proposed that its implementation may benefit the epidemiological investigations.     

Ecological plasticity and commercial impact of invasive marbled crayfish populations in Madagascar

Background

As plants, algae and some sessile invertebrates may grow in nearly monospecific assemblies, their collective biomass increases and if they compete hard enough some die, freeing up space. The concurrent increase in biomass and decrease in density is called self-thinning, and its trajectory over time or maximum values represent a boundary condition. For a single stand developing over time the boundary defines the carrying capacity of the environment but the most extreme trajectories emulate the efficiency of species in packing biomass into space.

Results

Here we present a meta-analysis of compiled data on biomass and density from 56 studies of 42 species of seaweeds from 8 orders within 3 phyla scattered through the world’s oceans. Our analysis shows that, with respect to biomass, seaweeds are the most efficient space occupiers on Earth because they transgress previously fixed limits derived from land plants. This is probably because seaweeds are not limited by water and do not need structures for its transport or for transpiration; they photosynthesise and uptake nutrients over their entire surface; they are attached to the substrate by holdfasts that are small proportional to their volume or weight compared to roots; water provides them better support, reducing the need for tissues for rigidity. We also identified a biomass concentration common to plants and seaweeds which represents the threshold that no life on the planet can pass. Using each stand’s distance to the biomass–density boundary, we determined that within the seaweeds the efficiency of space occupation differed amongst taxonomic and functional groups as well as with clonality and latitude.

Conclusions

Algae occupy space more efficiently than plants, most likely because the watery environment facilitates the physical processes and integration of space occupation. The distance-to-the-boundary proves a good metric to discriminate among groups and may be useful for comparison of the most efficient biomass producing systems, or for the identification of systems impacted by pollution.

     

Effects of seed priming on growth and antioxidant components of hairy vetch (Vicia villosa) seedlings under chilling stress

Hairy vetch (Vicia villosa) is an important cover crop and green manure in dryland cropping system of Mediterranean regions. A delay in the onset of rainfall during autumn can inhibit hairy vetch seed germination, which exposes its early growth stages to low-temperature stress. The present study was carried out in a completely randomized design with four replications to evaluate the effects of seed priming on germination of hairy vetch under chilling stress. The treatments were seed-priming type (unprimed, hydro-priming, halo-priming, and osmopriming) and temperature (3, 6, 9, 12, and 15?°C). The results indicated that a decrease in temperature produced a linear decline in the germination rate of seeds treated with halo-priming and osmopriming (p?<?.01). The seedling length, seedling dry weight, and vigor index decreased in plants experiencing chilling stress (quadratic; p?<?.01) for hydro-priming, halo-priming, and osmopriming. The maximum germination rate was achieved using hydro-priming. Osmopriming prevented a decrease in the rate of germination at 3?°C. A decrease in temperature increased the proline and the soluble protein contents in all the seed priming treatments, but, decreased catalase and guaiacol peroxidase activity (p?<?.01). In brief, halo-priming, and hydro-priming enhanced establishment and growth of hairy vetch under chilling stress primarily through improvements in the physiological parameters and germination rate. This finding can increase the potential for cultivation of the hairy vetch in late planting date.     

Topochemical investigation into the delignification of Eucalyptus globulus chips during semi-chemical sulfite pulping

The course of delignification of Eucalyptus globulus fibers during neutral semi-chemical sulfite pulping (NSSC) was studied by universal microspectrophotometry (UMSP 80, ZEISS). UV-investigation into a cellular level enables the topochemical analyses of delignification within individual cell wall layers during cooking. Cooks were carried out in a laboratory seven liter digester with liquor circulation and electrical heating device. Chip samples were taken throughout the cooking for chemical and UV microscopic analyses. UV microscopy analysis revealed for Eucalyptus globulus chips a preferred lignin removal during NSSC cooking in cell corner and compound middle lamella regions.     

Seed priming improves seedling emergence and reduces oxidative stress in Nigella sativa under soil moisture stress

Nigella sativa seeds have multiple industrial and pharmaceutical uses for the diseases treatment such as bronchitis, rheumatism, high blood pressure, cough, eczema, inflammation, and influenza. Although semi-arid areas are suitable for production of annual medicinal plants because they receive favorable amounts of solar radiations, the establishment of these plants' seedling requires frequent irrigations because their seeds are small and the climate is hot at the time of planting. When the irrigation sources are limited, poor establishment and inadequate production will result. Therefore, in order to improve nitrogen (N) in N. sativa seedling establishment, different effects of seed priming treatments were evaluated under drought stress. Different levels of soil moisture (irrigation after 11, 22, 33, and 44 mm of evaporation as no water stress, mild water stress, moderate water stress, and severe water stress, respectively) and seed priming treatments [no priming, potassium nitrate (KNO₃), zinc sulfate (ZnSO₄), polyethylene glycol 6000, and gibberellic acid (GA)] were evaluated as the main plot and subplot factors, respectively. The results showed that under mild water stress condition, seed priming significantly increased proline content and the highest percentage of emergence was obtained with ZnSO₄. Furthermore, the highest amount of soluble protein was observed in the KNO₃ treatment and the catalase enzyme content increased in all priming treatments, except polyethylene glycol treatment. Under moderate water stress condition, the KNO₃ treatment raised the rate and percentage of emergence and the seedling length. However, under severe water stress condition, the highest percentage of emergence was achieved by GA and ZnSO₄ treatments. Moreover, hydropriming and GA produced the highest proline content and seedling dry weight. Under moderate and severe water stress conditions, the hydropriming and ZnSO₄ treatments showed a significant increase in catalase activity. It can be concluded that priming of N. sativa seeds with ZnSO₄ and GA can alleviate drought stress in the early stages of seedling growth by increasing the antioxidants in the seedlings. Farmers in semi-arid regions can prime N. sativa seeds with these compounds before planting to increase production of this valuable medicinal plant and reduce water consumption.     

The efficacy of eprinomectin extended-release injection against Hypoderma spp. (Diptera: Oestridae) in cattle

The efficacy of eprinomectin in an extended-release injection (ERI) formulation was determined in cattle harboring naturally acquired infestations of first- or second- and third-stage larvae of Hypoderma spp. in three studies conducted according to the same protocol in the USA (two studies) and Germany (one study). Thirty cattle sourced from herds with a history of Hypoderma infestation were included in each study. Cattle were formed into replicates of three animals each on the basis of pre-treatment anti-Hypoderma antibody titers. Within replicates each animal was randomly allocated to one of the following treatments: ERI vehicle (control) at 1 mL/50 kg bodyweight, administered once on Day 0; Eprinomectin 5% ERI at 1 mL/50 kg bodyweight (1.0 mg eprinomectin/kg), administered once on Day 0 (when larvae were expected to be first instars); or Eprinomectin 5% ERI at 1 mL/50 kg bodyweight (1.0 mg eprinomectin/kg), administered once when larvae were second or third instars (study dependent, Day 73, 119, or 140). Treatments were administered by subcutaneous injection in front of the shoulder. In all studies, emerging and/or expressed Hypoderma larvae were recovered, speciated, and counted and viability was determined. Eprinomectin LAI treatment was 100% (p < 0.05) efficacious against first- and second- or third-stage larvae of Hypoderma bovis (two studies) and Hypoderma lineatum (one study). All animals accepted the treatment well. No adverse reaction to treatments was observed in any animal in any study.     

Strategic tillage in Australian conservation agricultural systems to address soil constraints: How does it impact weed management?

In the conservation agricultural systems practised in Australia, cultivation is not commonly utilised for the purpose of weed control. However, occasional use of tillage (strategic tillage) is implemented every few years for soil amelioration, to address constraints such as acidity, water repellence or soil compaction. Depending on the tillage method, the soil amelioration process buries or disturbs the topsoil. The act of amelioration also changes the soil physical and chemical properties and affects crop growth. While these strategic tillage practices are not usually applied for weed control, they are likely to have an impact on weed seedbank burial, which will in turn affect seed dormancy and seedbank depletion. Strategic tillage impacts on seed burial and soil characteristics will also affect weed emergence, plant survival, competitive ability of weeds against the crop and efficiency of soil applied pre-emergent herbicides. If growers understand the impacts of soil amelioration on weed demography, they can more effectively plan management strategies to apply following the strategic tillage practice. Weed seed burial resulting from a full soil inversion is understood, but for many soil tillage implements, more data is needed on the extent of soil mixing, burial of topsoil and the weed seedbank, physical control of existing weeds and stimulation of emergence following the tillage event. Within the agronomic system, there is no research on optimal timing for a tillage event within the year. There are multiple studies to indicate that strategic tillage can reduce weed density, but in most studies, the weed density increases in subsequent years. This indicates that more research is required on the interaction of amelioration and weed ecology, and optimal weed management strategies following a strategic tillage event to maintain weeds at low densities. However, this review also highlights that, where the impacts of soil amelioration are understood, existing data on weed ecology can be applied to potentially determine impacts of amelioration on weed growth.     

Dynamics of soil protozoa using a direct count method

We adapted a direct count method for obtaining counts of active protozoa that was not overly time consuming. Soil samples from an agricultural field were examined at 1- to 3-day intervals three times through the year. The three sampling periods represented different weather conditions. At each sampling event, fresh soil samples were extracted upon return to the laboratory for protozoa. These were enumerated at the microscope without prior culture, in soil–water suspension dilutions. We describe a procedure that allowed all samples to be processed in a few hours. Our results suggest there is good reproducibility and agreement between samples collected on the same day. Our data resolve differences between days as soil conditions changed slowly with drying or wetting. This procedure is suitable for describing species active at the time of sampling. Unlike the ‘most probable number’ procedure that relies on cultivable species, it is less prone to enumerating excysting individuals, and it provides better resolution between sampling dates, with a relatively low number of samples.     

Genetic Diversity Among <Emphasis Type="Italic">Juglans Regia</Emphasis> Genotypes Based on Morphological Characters of Nut

Walnut germplasm from three different sites in Oltenia region, located in the southwestern part of Romania, was evaluated to determine the variability and to identify promising types. A total of 64 genotypes were evaluated using morphological characteristics of nuts. Considerable genetic variation in the measured traits was found in native trees which were of seedling origin. Variability found was between 7.62–20.90?g in nut weight, between 31.17 and 53.60?mm in nut length, between 24.81 and 37.48?mm in nut diameter I, and between 23.64 and 36.18?mm in nut diameter II. Separation of the three areas in multivariate space was assessed by calculating the Mahalanobis distance. The highest inter-populations value was observed between Bechet and Ostroveni population (1.83), followed by Sadova and Ostroveni population (1.08), which indicates a wide genetic distance between these populations. Cluster analyses showed a considerable diversity within the same germplasm population. The results indicated that most of genotypes were suitable in terms of morphological traits of nut. These data demonstrated large phenotypic diversity of nut among the selected genotypes that can be considered as a valuable gene stock for breeding programs.